WO2020089019A1

WO2020089019A1 - Method for producing a multilayer coating structure with a top layer made of silane group-containing prepolymers

Info

Publication number: WO2020089019A1
Application number: PCT/EP2019/078965
Authority: WO
Inventors: Florian Golling; Andreas Hecking; Raul Pires; Hans-Josef Laas; Jan Weikard
Original assignee: Covestro Deutschland Ag
Priority date: 2018-10-30
Filing date: 2019-10-24
Publication date: 2020-05-07

Abstract

The invention relates to a method for producing an at least two-layer coating structure made of a lower base coating layer and an upper top coating layer arranged over the base coating on a substrate. The method has the steps of: a) applying a base coating layer comprising polymers selected from the group consisting of polyacrylates, polyurethanes, polyether polyols, polycarbonate polyols, polyester polyols, melamine resin, alkyd resin, or mixtures thereof onto a substrate; b) at least partly curing the base coating layer; c) applying a top coating onto the base coating layer applied in step b), said top coating comprising, as structure-forming components, a content of more than or equal to 20 wt.% and less than or equal to 100 wt.%, based on the cured top coating layer, of silane group-containing prepolymers and a content of more than or equal to 0.01 wt.% and less than or equal to 5 wt.%, based on the cured top coating layer, of a catalyst, wherein the catalyst is selected from the group consisting of protonic acids or mixtures thereof; and d) reacting the layer applied in step c) in order to obtain the top coating layer. The invention additionally relates to a layer composite consisting of the two layers according to the invention, to the use of the coating structure according to the invention for coating a substrate, and to a vehicle body part with the coating according to the invention.

Description

Process for producing a multi-layer lacquer structure with a top layer made of prepolymers containing silane groups

The present invention relates to a method for producing an at least two-layer lacquer structure from a lower basecoat and an upper topcoat layer arranged above it on a substrate, the method comprising the steps of: a) applying a basecoat layer comprising polymers selected from the group consisting of polyacrylates , Polyurethanes, polyether polyols, polycarbonate polyols, polyester polyols, melamine resins, alkyd resins or mixtures thereof on a substrate; b) at least partial curing of the basecoat film; c) applying a topcoat to the basecoat layer applied in step b), the topcoat being the structuring component containing prepolymers containing silane groups with a content of greater than or equal to 20% by weight and less than or equal to 100% by weight based on the cured topcoat layer and comprises a catalyst with a content of greater than or equal to 0.01% by weight and less than or equal to 5% by weight, based on the cured topcoat layer, and the catalyst is selected from the group consisting of protonic acids or mixtures thereof; and d) reacting the layer applied in step c) to obtain the top coat layer. The invention further relates to a layer composite of the two layers according to the invention, the use of the invention for coating a substrate and a body part with the coating according to the invention.

The functionalization of surfaces by applying additional layers on workpieces is an important process that is used in many industrial areas. In addition to purely aesthetic properties, this additional step can also be used to change important usage properties of the workpieces, so that one-size-fits-all adjustments can be achieved. This flexibility is all the more important in the consumer goods industry, which expects a certain degree of customization based on standard components to diversify the product portfolio. It is customary for high-quality goods, such as automobiles, that the external appearance can be individualized on the basis of a (freely) selectable paint color. This painting is usually carried out in several layers, since only one layer as such cannot have all of the required properties. In this respect, a primer is first applied to multilayer automotive paint structures, which, depending on the substrate, is intended to improve the adhesion between the substrate and the subsequent layer or layers. This coating can also serve to protect the substrate from corrosion if it is susceptible to corrosion. In addition, the primer improves the surface quality by covering any roughness and structure of the surface. A filler is often applied to the primer, particularly in the case of metal substrates, the purpose of which is to further improve the Surface quality and the improvement of the risk of falling rocks. One or more coloring and / or effect layers, which are referred to as basecoat, are usually applied to the filler. Finally, a highly cross-linked top coat is applied to the basecoat, which ensures the desired glossy look and protects the paint structure from environmental influences.

If predominantly clear topcoat layers are to be obtained, for example, silane-functional prepolymers, in particular silane-functional polyurethane prepolymers, can be used to build up topcoat layers. The preparation of polyurethanes containing silane groups can be carried out in various ways, for example by reaction of polyisocyanates or isocyanate-functional prepolymers with silane compounds which are reactive toward isocyanate groups, such as, for. B. secondary aminoalkylsilanes or mercaptoalkylsilanes.

The synthesis of specially partially silanized high-molecular alkoxysilane-functionalized polyols and low-molecular alkoxysilanes is described in the literature. One possibility is to use hydroxy-functional compounds such as e.g. B. polyether, polyurethane or polyester polyols, with isocyanato-organosilanes, such as the isocyanatoalkylalkoxysilanes described in US 3,494,951 or EP-A 0 649 850. Another possibility is the reaction of isocyanatopropyltrimethoxysilane or isocyanatopropyltriethoxysilane with polyols as disclosed in WO 2009/115079.

Adducts of isocyanatoalkylalkoxysilanes, such as. B. isocyanatopropyltrimethoxysilane, and low molecular weight, up to 20 carbon atoms containing, branched diols or polyols are the subject of EP-A 2 641 925. In addition to the low molecular weight branched diols or polyols, up to a proportion of 40 wt .-% further diols and / or polyols, including, for example hydroxyl-containing polyesters or polyacrylates can also be used. For example, WO 2013/189882 describes adducts of isocyanatotrialkyoxysilanes and polyhydric alcohols as additional crosslinking agents in non-aqueous two-component polyurethane coatings (2K-PUR).

WO 2014/180623 describes moisture-crosslinking coating compositions which contain at least one adduct of an isocyanatosilane with a hydroxy-functional compound, a tin-containing catalyst and an aminosilane. Monohydric or polyhydric alcohols and polyols are mentioned as suitable hydroxy-functional compounds for the preparation of the adducts, including, in a long list of suitable polymeric polyols, also hydroxy-functional polyacrylates. In the exemplary embodiments of WO 2014/180623, Vestanat M 95, however, only uses a low molecular weight 2: 1 adduct (molar) of isocyanatopropytrimethoxysilane and 1,9-nonanediol. WO 2008/034409 describes, by way of example, the partial conversion of a commercially available polyester polyol Desmophen 1145 (Covestro Deutschland AG) with a deficit of isocyanatopropyltriethoxysilane. Because of the selected equivalent ratio, less than 15% of the hydroxyl groups originally present in the polyol are urethanized. Furthermore, WO 2014/037265 discloses the production of silane-functional binders with a thiourethane structure by reacting polyols with low-monomer diisocyanate mercaptosilane adducts.

The prior art frequently discloses silane-functional polymers as an additional crosslinking component in paint structures. These layers use "usual" paint build-up polymers and modify their properties by adding this additional component. On the other hand, the build-up of lacquer layers mainly based on silane-functional polymers is much less common. This is partly due to the fact that top layers with silane-functional polymers as main components on the different base layers show significantly more complex drying properties than the varnishes commonly used. The coating properties vary significantly more and the drying kinetics are significantly worse than those of the known paints.

For these reasons, there is still a need in the prior art for suitable combinations of base and silane-functional topcoats, the layer composite being intended to have comparable functional and drying properties to the known paint coatings. It is therefore the object of the present invention to provide a method for producing functional layer composites with silane-functional topcoat layers, the layer composite showing good mechanical properties and excellent drying kinetics. It is also the object of the present invention to provide a laminate with these good mechanical properties and a body part coated with the laminate.

According to the invention, the object is achieved for the method by the features of claim 1 and for a layer composite according to the invention by the features of claim 11. Advantageous further developments are specified in the subclaims. They can be combined as required, unless the context clearly indicates the opposite. According to the invention, the references to “comprising”, “containing” etc. preferably mean “essentially consisting of” and very particularly preferably “consisting of”.

According to the invention is a method for producing an at least two-layer lacquer structure from a lower basecoat and an upper topcoat layer arranged above it on one Substrate, the method comprising the steps of: a) applying a basecoat layer comprising polymers selected from the group consisting of polyacrylates, polyurethanes, polyether polyols, polycarbonate polyols, polyester polyols, melamine resins, alkyd resins or mixtures thereof on a substrate; b) at least partial curing of the basecoat film; c) applying a topcoat to the basecoat layer applied in step b), the topcoat being the structuring component containing prepolymers containing silane groups with a content of greater than or equal to 20% by weight and less than or equal to 100% by weight based on the cured topcoat layer and comprises a catalyst with a content of greater than or equal to 0.01% by weight and less than or equal to 5% by weight, based on the cured topcoat layer, and the catalyst is selected from the group consisting of protonic acids or mixtures thereof; and d) reacting the layer applied in step c) to obtain the top coat layer. Surprisingly, it was found that the above two-layer paint structure has excellent mechanical properties. The resulting lacquer composite is highly elastic and both layers show very good adhesion. This is highly surprising, since normally prepolymers containing silane groups have property profiles that depend strongly on the substrate and actually only adhere poorly to the above-mentioned basecoats. This is in contrast to other substrates such as glass, on which the silane group-containing

Prepolymers have reasonable adhesion. In addition to the adhesion as such, the drying behavior of the topcoat layer is also surprising, since normally topcoat layers composed of prepolymers containing silane groups on base coat layers of the abovementioned polymers have only insufficient drying properties. In contrast to drying on glass, drying takes place only very slowly, which prevents economical use.

The procedure shown here, however, makes it possible that within a short time

Drying times mechanically stable layer composites can be obtained from at least two layers. Without being bound by theory, the stability of the composite with a topcoat layer of silane group-containing prepolymers seems to be achievable over the specially selected catalysts, which apparently do not only lead to a mechanical one

Stabilization of the top coat layer but also contribute to further, favorable interactions between the top coat and basecoat layer. Through the use of this catalyst group in the curing of the upper topcoat layer, important interactions between the two boundary layers of the base layer and the top layer also appear to be connected. According to the invention, the catalyst is selected from the group consisting of protonic acids or mixtures thereof. To clarify, it should be noted that amine-blocked or amine-neutralized derivatives of the above-mentioned protonic acids are not catalysts according to the invention. Likewise, Lewis acids, such as, for example, aluminum compounds, in particular aluminum triisopropylate, aluminum tri-sec-butoxide and other alcoholates and aluminum acetylacetonate, are not catalysts according to the invention.

According to the invention, an at least two-layer lacquer structure is produced. The two-layer structure according to the invention can be used as the sole structure for modifying a substrate or in combination with further layers. For example, it is possible that, starting from the substrate, there are other lacquer layers in addition to the base lacquer layer. The other layers of paint are then below the basecoat. The lacquer layer structure according to the invention is thus characterized by a physical contact between the base lacquer layer according to the invention and the top lacquer layer according to the invention. Additional layers can also be arranged above the topcoat layer, which can be applied independently of the topcoat layer according to the invention after it has hardened. It is also a sandwich from the composite according to the invention, which has the combination of both layers on the inside.

The layer composite has at least a lower basecoat and an upper topcoat layer arranged above it. This means that from the substrate to the air side, the basecoat is closer to the substrate and the topcoat layer is closer to the air. The upper topcoat layer can be a clearcoat layer, this means that the topcoat layer is transparent and the optical properties of the layer composite are determined via the optical properties of the basecoat film. The transparency of a pigmented or unpigmented system means its property of scattering the light as little as possible. Accordingly, the color change of the black background should be as small as possible when applied to a black background. The transparency of the pigmented or unpigmented system is higher, the smaller the color difference from the black background. The transparency of a top coat is determined based on DIN 55988: 2013-04.

The two-layer composite is arranged on a substrate. Suitable substrates are known to the person skilled in the art. The layered composite can be applied to solid substrates such as glass or metal. However, it is also possible for polymeric carrier materials to be used as substrates, for example printed circuit boards. Suitable metal surfaces are for example iron, steel, aluminum or the like. For a coating, the substrates can be uncoated or coated. As a coating, for example, primers and / or fillers may already have been applied to the substrate before it is used in the method according to the invention. Examples of primers are, in particular, cathodic dip coatings, such as those used in automotive painting, solvent-based or aqueous primers for plastics, in particular for plastics with low surface tension, such as PP or PP-EPDM.

The substrates to be provided can be a body or parts thereof, which comprises one or more of the aforementioned materials. The body or parts thereof preferably comprise one or more materials selected from metal, plastic or mixtures thereof.

The substrate can comprise metal, in particular the substrate can contain 80% by weight, 70% by weight, 60% by weight, 50% by weight, 25% by weight, 10% by weight, 5% by weight. -%, 1 wt .-% consist of metal.

The substrate can at least partially consist of a composite material, in particular a composite material comprising metal, glass, carbon fiber and / or plastic.

In a first step a), a basecoat layer comprising polymers selected from the group consisting of polyacrylates, polyurethanes, polyether polyols, polycarbonate polyols, polyester polyols, melamine resins, alkyd resins or mixtures thereof is applied to a substrate. This first step together with the next step leads to the formation of the basecoat layer. The substrate can of course also be pretreated by further steps above, for example by smoothing, roughening or cleaning the surface.

The basecoat can be a one-component (IC) system, a two-component (2K) or multi-component (3K, 4K) system. A one-component (IC) system is to be understood as a thermally curing coating material in which the binder and the crosslinking agent are side by side, i.e. in one component.

This can also be understood to mean a coating material in which, in particular, the binder and the crosslinking agent are present separately from one another in at least two components which are only combined shortly before application. This form is selected when the binder and crosslinking agent already react with one another at room temperature. Coating materials of this type become thermal especially for coating sensitive substrates, especially in automotive refinishing.

The first constituent of the coating material of the basecoat can comprise at least one, in particular one, saturated, unsaturated and / or grafted with olefinically unsaturated compounds, ionically and / or non-ionically stabilized polyurethane (A), preferably based on aliphatic, cycloaliphatic, aliphatic-cycloaliphatic, aromatic, araliphatic, aliphatic-aromatic and / or cycloaliphatic-aromatic polyisocyanates. For stabilization, the polyurethane (A) can either contain (A) either contain

(al) functional groups which can be converted into cations by neutralizing agents and / or quaternizing agents, and / or cationic groups or

(a2) functional groups which can be converted into anions by neutralizing agents and / or anionic groups and / or

(a3) non-ionic hydrophilic groups

They are contained in the usual and known amounts in the coating material.

If the coating material is physically, thermally self-crosslinking or thermally self-crosslinking and curable with actinic radiation, its polyurethane content (A) is preferably 50 to 100% by weight, preferably 50 to 90% by weight and in particular 50 to 80% by weight .-%, each based on the film-forming solid of the coating material.

If the coating material is thermally crosslinking or thermally crosslinking and curable with actinic radiation, its polyurethane content (A) is preferably 10 to 80, preferably 15 to 75 and in particular 20 to 70% by weight, in each case based on the film-forming solid of the coating material.

The film-forming solid is to be understood as the sum of all constituents of the coating material which build up the solid of the thermoplastic or thermosetting materials produced therefrom, preferably the thermoplastic or thermosetting coatings, adhesive layers, seals, foils and moldings, in particular the thermosetting coatings.

The second constituent of the coating material can be a wetting or dispersing agent (B) which is selected from the group consisting of hyperbranched polymers, polyether-modified polydimethylsiloxanes, ionic and non-ionic (meth) acrylate copolymers, high-molecular block copolymers with pigment-affine groups and dialkyl sulfosuccinates. In particular, hyperbranched polymers are used. The wetting or dispersing agents (B) are known, commercially available materials and are, for example, from BASF under the brands Starfactant 20 and Hydropalat 875, from Byk Chemie under the brands Disperbyk 162, 163 and 182 and Byk 348 , 355, 381 and 390, distributed by Coatex under the Coatex P90 and BP3 brands and Efka under the Efka 4580 brand. Starfactant 20 is used in particular.

The wetting or dispersing agents (B) are used in the customary and known, effective amounts. They are preferably used in an amount of 0.01 to 5, preferably 0.05 to 2.5 and in particular 0.1 to 1.5% by weight, in each case based on the coating material.

The third component of the coating material can be at least one organic solvent (C). Suitable solvents are described, for example, in German patent application DE 102 005 060 A1, page 5 to page 6, paragraphs [0038] to [0040]. The solvent can preferably be triethylene glycol.

The amount of organic solvent (C) can vary widely and can thus be optimally adapted to the requirements of the individual case. However, in view of the aqueous nature of the coating material, efforts are made to keep its organic solvent (C) content as low as possible. It is a particular advantage here that an organic solvent (C) content of the coating material of 0.1 to 10, preferably 0.5 to 7 and in particular 0.5 to 5% by weight, based in each case on the coating material, is sufficient to achieve beneficial technical effects.

In addition, the coating material can also contain an additive (D). It preferably contains at least two additives (D). The additive (D) is preferably selected from the group of additives usually used in the field of coating materials. The additive (D) from the group consisting of residue-free or essentially residue-free thermally decomposable salts is particularly preferred; binders which are different from the polyurethanes (A) and are curable physically, thermally and / or with actinic radiation; Crosslinking agents; organic solvents other than organic solvents (C); thermally curable reactive thinners; reactive diluents curable with actinic radiation; coloring and / or effect pigments; transparent pigments; Fillers; molecularly dispersible luminescent materials; Nanoparticles; Light stabilizers; Antioxidants; Deaerators; Emulsifiers; Slip additives; Polymerization inhibitors; Radical polymerization initiators; thermolabile free radical initiators; Adhesion promoters; Leveling agents; film-forming aids, such as thickeners and pseudoplastic Sag control agents, SCA; Lamb protection agents; Corrosion inhibitors; Flow aids; To grow; Desiccants; Biocides and matting agents; selected. Suitable additives (D) of the type mentioned above are, for example, from German patent application DE 199 48 004 A1, page 14, line 4, to page 17, line 5, and German patent application DE 199 14 98 Al, column 11, line 9, to Column 15, line 63, or the German patent DE 100 43 405 CI, column 5, paragraphs [0031] to [0033]. They are used in the usual and known, effective amounts.

The solids content of the coating material can vary very widely and can therefore be optimally adapted to the requirements of the individual case. The solids content primarily depends on the viscosity required for the application, in particular spray application, so that it can be adjusted by the person skilled in the art on the basis of his general specialist knowledge, possibly with the aid of less orienting experiments. The solids content is preferably 5 to 70, preferably 10 to 65 and in particular 15 to 60% by weight, in each case based on the coating material.

The coating material is preferably produced using a coating process. The constituents (A), (B) and (C) and optionally (D) described above are dispersed in an aqueous medium, in particular in water, after which the resulting mixture is homogenized. From a methodological point of view, the method has no special features in terms of method, but can be carried out using the customary and known mixing processes and mixing units, such as stirred kettles, dissolvers, agitator mills, kneaders, static mixers, extruders, or in a continuous process. Because of the advantages of the coating material and the coating material produced by means of the method, numerous purposes can be fulfilled. They are preferably used for the production of the thermoplastic and thermosetting, in particular thermosetting, materials. They are preferably used as coating materials for the production of thermoplastic and thermosetting, in particular thermosetting, coatings, which can be bonded to primed and unprimed substrates of all kinds in a adhesively bonded or detachable manner.

Examples of suitable substrates are known from German patent application DE 199 48 004 A1, page 17, lines 12 to 36, or German patent DE 100 43 405 CI, column 2, paragraph [0008], to column 3, paragraph [0017] . The coating materials are particularly preferably used as topcoats for the production of topcoats or as water-based lacquers for the production of color and / or effect multi-layer coatings. They are very particularly preferred as water-based basecoats for the production of color and / or effect basecoats of multi- layer coatings, preferably multi-layer coatings for automobile bodies, used.

Multilayer coatings can very particularly preferably be produced using a wet-on-wet method, with at least one water-based lacquer being applied to a primed or unprimed substrate, resulting in at least one water-based lacquer layer.

Due to the application properties of the coating material, the thermoplastic and thermoset materials produced from it also have an outstandingly balanced physico-chemical, optical and mechanical property profile. Therefore, the films and molded parts as well as the substrates coated with the coatings have a particularly high utility value and a long service life.

Additional basecoat layers can be basecoat layers for low stoving temperatures.

An exemplary embodiment includes a curable coating composition for a low bake temperature basecoat: a crosslinkable component comprising an acid functional acrylic copolymer polymerized from a monomer mixture comprising 2% to 12% by weight of one or more Monomers containing carboxylic acid group (s), the percentages based on the total weight of the acid-functional acrylic copolymer, a crosslinking component; and a low baking temperature control agent comprising a rheology component selected from an amorphous silica gel, a clay, or a combination thereof, the rheology component being present in an amount of about 0.1 to about 10% by weight and about 0.1% to about 10% by weight polyurea, the percentages being based on the total weight of the crosslinkable and crosslinking components.

In an exemplary embodiment, the multi-layer coating system includes: a curable basecoat coating for a low baking temperature comprising: a crosslinkable component comprising an acid functional acrylic copolymer polymerized from a monomer mixture comprising 2% by weight to 12% by weight of monomers containing one or more carboxylic acid groups, the percentages being based on the total weight of the acid functional acrylic copolymer, a crosslinking component; and a low baking temperature control agent comprising a rheology component selected from an amorphous silica gel, a clay, or a combination thereof, the rheology component being present in an amount from about 0.1 to about 10 percent by weight and about 0.1 % By weight to about 10% by weight of polyurea, the percentages being based on the total weight of the crosslinkable and crosslinking components. In coating applications, particularly automotive repair or OEM applications, productivity is a critical factor, that is, the ability of a layer of coating composition to dry quickly to a "strike-in" or mix-resistant condition, such that Subsequent coating layer, such as a layer formed from a clear coating composition, which does not negatively influence the underlying layer. Once the top layer has been applied, the multilayer structure or system should then harden sufficiently quickly without negatively affecting the uniformity of color and appearance "Invention addresses the foregoing aspects by utilizing unique crosslinking technology and an additive. Thus, the present coating composition includes a crosslinkable and crosslinking component. ***"

The crosslinkable component includes from about 2% to about 25%, preferably from about 3% to about 20%, more preferably from about 5% to about 15% by weight of one or more acid-functional acrylic Copolymers, all percentages based on the total weight of the crosslinkable component. If the composition contains more than the upper limit of the acid functional acrylic copolymer, the resulting composition will typically have more than the required application viscosity. If the composition contains less than the lower limit of the acid-functional copolymer, the coating obtained would have insignificant strike-in (or mixing) properties for a multilayer structure or system or scale or flake orientation.

Generally have control.

The crosslinkable component contains an acid functional acrylic copolymer polymerized from a monomer mixture comprising about 2% to about 12%, preferably about 3% to about 10%, more preferably about 4% by weight Wt .-% to about 6 wt .-% of one or more carboxylic acid containing monomers, all percentages on the

Total weight of the acid-functional acrylic copolymer is based. If the amount of carboxylic acid group-containing monomer in the monomer mixture exceeds the upper limit, the coatings resulting from such a coating composition would have unacceptable water sensitivity, and if the amount was less than the lower limit, the coating obtained would become insignificant " Strike-in "properties for a multilayer structure or system or scale orientation control in general.

The acid-functional acrylic copolymer preferably has a weight average molecular weight according to GPC (in g / mol), determined in accordance with DIN 55672: 2016-03, in the range from about 8000 to about 100000, preferably from about 10,000 to about 50,000 and more preferably from about 12,000 to about 30,000. The copolymer preferably has a polydispersity in the range from about 1.05 to about 10.0, preferably in the range from about 1.2 to about 8, and more preferably in the range from about 1.5 to about 5. The copolymer preferably has a T _g ranging from about -5 ° C to about +100 ° C, preferably from about 0 ° C to about 80 ° C, and more preferably from about 10 ° C to about 60 ° C.

The monomers containing carboxylic acid group (s) suitable for use in the present invention include (meth) acrylic acid, crotonic acid, oleic acid, cinnamic acid, glutaconic acid, muconic acid, undecylenic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or a combination thereof. (Meth) acrylic acid is preferred. It is understood that users can also provide the acid functional acrylic copolymer having carboxylic acid groups by producing a copolymer polymerized from a monomer mixture containing anhydrides of the above-mentioned carboxylic acids and then hydrolyzing such copolymers to provide the obtained copolymer with carboxylic acid groups. contemplate. Maleic and itaconic anhydrides are preferred. Users may also consider hydrolyzing such anhydrides in their monomer mixture prior to polymerizing the monomer mixture to the acid functional acrylic copolymer.

It can be assumed that the presence of carboxylic acid groups in the copolymer of the present invention appears to increase the viscosity of the coating composition obtained due to the physical network formed by the well known hydrogen bonds of carboxyl groups. As a result, such increased viscosity supports "strike-in" properties in multi-layer structures or systems and scale orientation control in general.

The monomer mixture suitable for use in the present invention includes about 5 percent to about 40 percent, preferably about 10 percent to about 30 percent, of one or more functional (meth) acrylate monomers, all based on the total weight of the acid-functional acrylic Copolymers based. It should be noted that if the amount of functional (meth) acrylate monomers in the monomer mixture exceeds the upper limit, the pot life of the coating composition obtained is reduced, and if less than the lower limit is used, it will affect the coating properties obtained, such as durability, negatively influenced. The functional (meth) acrylate monomer can be provided with one or more crosslinkable groups selected from a primary hydroxyl, secondary hydroxyl, or a combination thereof.

Some of the suitable hydroxyl-containing (meth) acrylate monomers may have the following structure:

wherein RH is methyl and X is a divalent unit which can be substituted or unsubstituted Ci to Ci8 linear aliphatic unit or substituted or unsubstituted C3 to Cis branched or cyclic aliphatic unit. Some of the suitable substituents include nitrile, amide, halide such as chloride, bromide, fluoride, acetyl, acetoacetyl, hydroxyl, benzyl and aryl. Some specific hydroxyl-containing (meth) acrylate monomers in the monomer mixture include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate a.

The monomer mixture can also include one or more non-functional (meth) acrylate monomers. When used here, non-functional groups are those that do not crosslink with a crosslinking component. Some of suitable non-functional CI to C20 alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, isodecyl (meth) acrylate and lauryl (meth) acrylate; branched alkyl monomers such as isobutyl (meth) acrylate, t-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; and cyclic alkyl monomers such as cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, trimethylcyclohexyl (meth) acrylate, tertiary butylcyclohexyl (meth) acrylate and isobornyl (meth) acrylate. Isobornyl (meth) acrylate and butyl acrylate are preferred.

The monomer mixture can also include one or more of other monomers for the purpose of achieving the desired properties, such as hardness, appearance, and damage resistance. Some of the other such monomers include, for example, styrene, alpha-methylstyrene, acrylonitrile and methacrylonitrile. If included, the monomer mixture preferably includes such monomers in the range of about 5 percent to about 30 percent, all percentages being in weight percent based on the total weight of the polymer solids. Styrene is preferred.

Any conventional bulk or solution polymerization process can be used to make the acid functional acrylic copolymer of the present invention. One of the suitable methods for making the copolymer of the present invention includes free radical solution polymerization of the monomer mixture described above.

The polymerization of the monomer mixture can be carried out by adding conventional heat initiators, such as Azos, exemplified by Vazo 64, obtained from DuPont Company, Wilmington, Delaware; and peroxides such as t-butyl peroxyacetate are started. The molecular weight of the copolymer obtained can be controlled by adjusting the reaction temperature, the selection and the amount of the initiator used, as carried out by a person skilled in the art. The crosslinking component of the present invention can include one or more polyisocyanates, melamines, or a combination thereof. Polyisocyanates are preferred.

Typically, the polyisocyanate is provided in the range of about 2 to about 10, preferably about 2.5 to about 8, more preferably about 3 to about 5 isocyanate functionalities. Generally, the ratio of equivalents of isocyanate functionalities to the polyisocyanate per equivalent of all of the functional groups present in the crosslinking components ranges from about 0.5 / 1 to about 3.0 / 1, preferably from about 0 .7 / 1 to about 1.8 / 1, more preferably from about 0.8 / 1 to about 1.3 / 1. Some suitable polyisocyanates include aromatic, aliphatic or cycloaliphatic polyisocyanates, trifunctional polyisocyanates, and isocyanate-functional adducts of a polyol and difunctional isocyanates. Some of the particular polyisocyanates include diisocyanates such as 1,6-hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate, 4,4'-biphenylene diisocyanate, toluene diisocyanate, 4,4-methylene dicyclohexyl diisocyanate,

Biscyclohexyl diisocyanate, xylylene diisocyanate, tetramethylene xylene diisocyanate, 1,4-H6-xylylene diisocyanate, ethyl ethylene diisocyanate, 1-methyltrimethylene diisocyanate, 1,3-phenylene diisocyanate, 1,5-naphthalene diisocyanate, bis- (4-isocyanatocyclohexodyl ether), bis (4-isocyanatocyclohexyl) ether .

Some of the suitable trifunctional polyisocyanates include triphenylmethane triisocyanate, 1,3,5-benzene triisocyanate and 2,4,6-toluene triisocyanate. Trimers of diisocyanate, such as the trimer of hexamethylene diisocyanate, sold under the trademark Desmodur N-3390 by Covestro AG, Leverkusen, North Rhine-Westphalia, and the trimer of isophorone diisocyanate are also suitable. Trifunctional adducts of triols and diisocyanates are also suitable. Trimers of diisocyanates are preferred and trimers of isophorone, pentamethylene and hexamethylene diisocyanates are more preferred.

Typically, the coating composition may contain from about 0.1% to about 40%, preferably from about 15% to about 35%, and more preferably from about 20% to about 30% by weight of the Include melamines, the percentages based on the total weight of composition solids.

Some of the suitable melamines include monomeric melamine, polymeric melamine-formaldehyde resin, or a combination thereof. The monomeric melamines close Low molecular weight melamines containing an average of three or more methylol groups etherified with a monohydric CI to C5 alcohol, such as methanol, n-butanol or isobutanol, per triazine nucleus and an average degree of condensation of up to about 2 and preferably im Range from about 1.1 to about 1.8, and have a mononuclear species content of not less than about 50% by weight. In contrast, the polymeric melamines have an average degree of condensation of more than about 1.9. Some such suitable monomeric melamines include alkylated melamines, such as methylated, butylated, isobutylated melamines, and mixtures thereof. Many of these suitable monomeric melamines are supplied commercially. For example, Cytec Industries Ine., West Patterson, New Jersey, Cymel 301 (degree of polymerization of 1.5, 95% methyl and 5% methylol), Cymel 350 (degree of polymerization of 1.6, 84% methyl and 16% methylol), 303, 325, 327, 370 and XW3106, all of which are monomeric melamines. Suitable polymeric melamines include high amino content melamine (partially alkylated, -N, -H) known as Resimene BMP5503

(Molecular weight 690, polydispersity of 1.98, 56% butyl, 44% amino), available from Solutia Ine., St. Louis, Missouri, or Cymell l58, provided by Cytec Industries Ine., West Patterson, New Jersey , a. Cytec Industries Inc. also supply Cymel 1130 with 80 percent solids (degree of polymerization 2.5), Cymel 1133 (48% methyl, 4% methylol and 48% butyl), both of which are polymeric melamines.

If desired, suitable catalysts contained in the crosslinkable component can accelerate the curing process of a pot mix of the coating composition.

When the crosslinking component includes polyisocyanate, the crosslinkable component of the coating composition preferably includes a catalytically active amount of one or more catalysts to accelerate the curing process. Generally, a catalytically active amount of the catalyst in the coating composition ranges from about 0.001 percent to about 5 percent, preferably ranges from about 0.005 percent to about 2 percent, more preferably ranges from about 0.01 percent to about 1 percent, all in % By weight, based on the total weight of crosslinkable and crosslinking component solids, are present. A wide variety of catalysts can be used, such as tin compounds, including dibutyltin dilaurate and dibutyltin diacetate; tertiary amines such as triethylene diamine. These catalysts can be used individually or in combination with carboxylic acids such as acetic acid or benzoic acid. A commercially available catalyst sold under the Fastcat 4202 trademark, ie dibutyltin dilaurate from Arkema North America, Inc. of Philadelphia, Pennsylvania, is particularly suitable. In the event that the crosslinking component includes melamine, it also preferably includes a catalytically active amount of one or more acidic catalysts to further increase the crosslinking of the components upon curing. Generally, the catalytically active amount of the acidic catalyst in the coating composition ranges from about 0.1 percent to about 5 percent, preferably in the range from about 0.1 percent to about 2 percent, more preferably in the range from about 0.5 percent to about 1.2 percent, all in weight percent based on the total weight of crosslinkable and crosslinking component solids. Some suitable acidic catalysts contain aromatic sulfonic acids such as dodecylbenzenesulfonic acid, para-toluenesulfonic acid and dinonylnaphthalenesulfonic acid, all of which are either unblocked or with an amine such as dimethyloxazolidine and 2-amino-2-methyl-1-propanol, N, N-dimethylethanolamine or a combination thereof are blocked. Other acidic catalysts that can be used are strong acids, such as phosphoric acids, especially phenylic acid phosphate, which can be unblocked or blocked with an amine. The crosslinkable component of the coating composition may further range from about 0.1 percent to about 95 percent, preferably from about 10 percent to about 90 percent, more preferably from about 20 percent to about 80 percent, and most preferably from about Include 30 percent to about 70 percent of an acrylic polymer, polyester, or a combination thereof, all based on the total weight of the crosslinkable component.

The acrylic polymer suitable for use in the present invention may have a weight average molecular weight (in g / mol) according to GPC that exceeds 2000, preferably in the range of about 3000 to about 20,000, and more preferably in the range of about 4,000 to about 10,000. The T _{g of} the acrylic polymer varies in the range from 0 ° C. to approximately 100 ° C., preferably in the range from approximately 10 ° C. to approximately 80 ° C.

The acrylic polymer suitable for use in the present invention can conventionally be made from typical monomers such as alkyl (meth) acrylates having alkyl carbon atoms in the range of 1 to 18, preferably in the range of 1 to 12, and styrene and functional monomers such as Hydroxyethyl acrylate and hydroxyethyl methacrylate can be polymerized.

The polyester suitable for use in the present invention may have a GPC weight average molecular weight exceeding 1500, preferably in the range of about 1500 to about 100000, more preferably in the range of about 2000 to about 50,000, more preferably in the range of about 2000 to about 8000 and particularly preferably in the range from about 2000 to about 5000. The T _{g of} the polyester varies in the range from about -50 ° C to about +100 ° C, preferably in the range from about -20 ° C to about +50 ° C.

The polyester suitable for use can be polymerized in a conventional manner from suitable polyacids, including cycloaliphatic polycarboxylic acids, and suitable polyols, including polyhydric alcohols. Examples of suitable cycloaliphatic

Polycarboxylic acids are tetrahydrophthalic acid, hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-

Methyl hexahydrophthalic acid, endomethylene tetrahydrophthalic acid, tricyclodecanedicarboxylic acid, endoethylene hexahydrophthalic acid, camphoric acid, cyclohexanetetracarbon and cyclobutanetetracarboxylic acid. The cycloaliphatic polycarboxylic acids can be used not only in their cis but also in their trans form and as a mixture of both forms. Examples of suitable polycarboxylic acids which, if desired, can be used together with the cycloaliphatic polycarboxylic acids are aromatic and aliphatic polycarboxylic acids, such as, for example, phthalic acid, isophthalic acid, terephthalic acid, halophthalic acids, such as tetrachloro- or tetrabromophthalic acid, adipic acid, glutaric acid, sebaric acid, sebacic acid, azine acid, sebacic acid, azine acid, sebacic acid, azine acid, sebacic acid, azine acid, sebacic acid, azide Fumaric acid, maleic acid, trimellitic acid and pyromellitic acid.

Suitable polyhydric alcohols include ethylene glycol, propanediols, butanediols, hexanediols, neopentyl glycol, diethylene glycol, cyclohexanediol, cyclohexanedimethanol, trimethylpentanediol, ethylbutylpropanediol, ditrimethylolpropane, trimethylolethane, trimethylolpropane, triethylglycol, tritylthryglycol, pentrylytyl glycol, pentrylytyl glycol, pentrylyl glycol, pentrylyl glycol, tritylthryglycol, pentrylyl glycol, pentrylyl glycol, pentrylyl glycol, pentrylyl glycol, pentrylyl glycol, pentrylytyl glycol, pentrylythritol, pentrylyl, pentrylytyl glycol. If desired, monohydric alcohols such as butanol, octanol, lauryl alcohol, ethoxylated or propoxylated phenols can also be included together with polyhydric alcohols.

The crosslinkable component can further include one or more reactive oligomers, such as non-alicyclic (linear or aromatic) oligomers, disclosed in US 6,221,494 B4, page 3, column 4, line 1 to line 48, which are incorporated herein by reference . Such non-alicyclic oligomers can be prepared using non-alicyclic anhydrides such as succinic or phthalic anhydrides or mixtures thereof. Caprolactone oligomers described in US 5,286,782 page 3, column 4, line 43 to column 5, line 57, which are incorporated herein by reference, may also be used.

The crosslinkable component of the coating composition may further include one or more modifying resins, which are also known as non-aqueous dispersions (NADs). Such resins are sometimes used to adjust the viscosity of the coating composition obtained. The amount of modifying resin that can be used is typically in the range of about 10% to about 50% by weight, with all products percentages are based on the total weight of crosslinkable component solids. The weight average molecular weight of the modifying resin, determined according to DIN 55672: 2016-03, is generally in the range (in g / mol) from about 20,000 to about 100,000, preferably in the range from about 25,000 to about 80,000 and more preferably in the range of about 30,000 to about 50,000.

The crosslinkable or crosslinking component of the coating composition of the present invention typically contains at least one organic solvent, typically from the group consisting of aromatic hydrocarbons such as petroleum naphtha or xylenes; Ketones such as methyl amyl ketone, methyl isobutyl ketone, methyl ethyl ketone or acetone; Esters such as butyl acetate or hexyl acetate; and glycol ether esters such as propylene glycol monomethyl ether acetate. The amount of organic solvent added depends on the desired solids content and the desired amount of VOC of the composition. If desired, the organic solvent can be added to both components of the binder. A high solids, low VOC coating composition is preferred.

If the following baking temperature control means with either the crosslinkable component, the crosslinking component, or both of the

Coating composition (preferably with the crosslinkable component), the run-off resistance of the layer applied to a substrate surface can be improved under the condition of a low baking temperature. The low bake temperature control agent of the present invention includes a rheology component. In an exemplary embodiment, the rheology component includes an amorphous silica gel, a clay, or a combination of both. In another exemplary embodiment, the low bake temperature control means includes from about 0.1% to about 10%, preferably from about 0.3% to about 5%, more preferably from about 0.5% % By weight to about 2% by weight of the rheology component, and in the range from approximately 0.1% by weight to approximately 10% by weight, preferably in the range from approximately 0.3% by weight to approximately 5 weight percent, and more preferably in the range of about 0.5 weight percent to about 2 weight percent of polyurea, the weight percentages being based on the total weight of the crosslinkable and crosslinking components of the curable, low bake coating composition of the present invention. If too little silica gel and polyurea are used (less than the ranges mentioned above), no advantage can be seen and if too much silica gel and polyurea are used (more than the ranges mentioned above), the coating surface obtained becomes rough. Suitable amorphous silica gels include colloidal silica gels, which are characterized by the Silanization of hydroxyl groups on the silica gel particles has been partially or completely surface modified, making some or all of the silica gel particle surface hydrophobic. Examples of suitable hydrophobic silica gel include ÄROSIL R972, ÄROSIL R812, ÄROSIL OK412, ÄROSIL TS-100 and ÄROSIL R805, all of which are commercially available from Evonik Industries AG, Essen, Germany. Pyrogenic silica gel is particularly preferably available from Evonik Industries AG, Essen, Germany, as ÄROSIL R 812. Other commercially available silica gel includes SIBELITE M3000 (Cristobalite), SIL-CO-SIL, ground silica gel, MIN-U-SIL, micronized silica gel, all of which are obtained from US Silica Gel Company, Berkeley Springs, West Virginia. The silica gel can be dispersed in the copolymer by a grinding process using conventional equipment such as high speed blade mixers, ball mills or sand mills. Preferably, the silica gel is separately dispersed in the previously described acrylic polymer and then the dispersion can be added to the crosslinkable component of the coating composition. The clay suitable for use herein may include clay, dispersed clay, or a combination thereof. Examples of commercially available clay products include bentonite clay, available as BENTONE from Elementis Specialties, London, UK, and GARAMITE clay, available from Southern Ton Products, Gonzales, TX, USA, under registered trademarks. BENTONE 34 dispersion, described in U.S. Patent No. 8,357,456, and GARAMITE dispersion, described in U.S. Patent No. 8,227,544, and a combination of the two are suitable. A combination of the silica gel and the clay such as the aforementioned BENTONE, GARAMITE or dispersions thereof can also be used.

The polyurea suitable for use in the low bake temperature control agent is obtained from the polymerization of a monomer mixture comprising about 0.5 to about 3 percent by weight of the amine monomers, about 0.5 to about 3 percent by weight of the isocyanate Monomers, and from about 94 to about 99 weight percent of a moderating polymer. The amine monomer is selected from the group consisting of a primary amine, secondary amine, ketimine, aldimine, or a combination thereof. Benzylamine is preferred. The isocyanate monomer is selected from the group consisting of an aliphatic polyisocyanate, cycloaliphatic polyisocyanate, aromatic polyisocyanate, and a combination thereof. The preferred isocyanate monomer is 1,6-hexamethylene diisocyanate or 1,5-pentamethylene diisocyanate. The moderating polymer can be one or more of the polymers described above. The acrylic polymers or polyesters are preferred.

Preferably the polyurea is obtained by mixing one or more of the Moderating polymers made with the amine monomers and then isocyanate monomers are added over time under ambient conditions.

The run-off resistance of a layer of a pot mix or mixing mixture, which results from mixing the crosslinkable and crosslinking components of the present coating composition when applied to a substrate, is in the range from about 5 (127 micrometers) to about 20 mils (508 microns) when measured by ASTM D4400-99. The higher the number, the higher the desired resistance to running.

The coating composition is preferably used as a two-component

Coating composition formulated, wherein the crosslinkable component is stored in a separate container from the crosslinking component, which is mixed to form a pot mix or a mixing batch shortly before use.

The coating composition is preferably used as an automotive OEM

Composition or formulated as an automotive repair composition. These compositions can be applied as a basecoat or as a pigmented single-coat topcoat to a substrate. These compositions require the presence of pigments. Typically a pigment to binder ratio of from about 1.0 / 100 to about 200/100 is used depending on the color and type of pigment used. The pigments are formulated into regrinds by conventional methods such as milling, sand milling, and high speed mixing. Generally, the millbase comprises pigment and a dispersant in an organic solvent. The millbase is added to the coating composition in an appropriate amount with mixing to form a pigmented coating composition.

Any of the commonly used organic and inorganic pigments, such as white pigments, for example titanium dioxide, color pigments, metallic flakes, for example aluminum flakes, special effect pigments, for example coated mica flakes and coated aluminum flakes, and extender pigments, can be used.

The coating composition can also include other conventional formulation additives such as wetting agents, leveling agents and flow control agents, for example Resiflow S

(Polybutyl acrylate), BYK 320 and 325 (high molecular weight polyacrylates), BYK 347 (polyether-modified siloxane), defoamers, surfactants and emulsifiers to make the

Include composition to help stabilize. Other additives that typically improve damage resistance can be added, such as silsesquioxane and other silicate-based microparticles.

To improve the weather resistance of the clear finish of the coating composition about 0.1% to about 5% by weight, based on the weight of the composition solids, of an ultraviolet light stabilizer or a combination of ultraviolet light stabilizers and absorbent may be added. These stabilizers include ultraviolet light absorbers, screeners, quenchers and special hindered amine light stabilizers. Also, about 0.1% to about 5% by weight, based on the weight of the composition solids, of an antioxidant can also be added.

The coating composition is preferably formulated in the form of a two-component coating composition. The present invention is particularly useful as a basecoat for outdoor objects such as vehicles and other vehicle body parts. The vehicle or the other vehicle body part can be constructed from one or more materials. Suitable materials are, for example, metal, plastic or their mixtures. The vehicle can be any vehicle known to those skilled in the art. For example, the vehicle can be a motor vehicle, fast motor vehicle, motorcycle, scooter, bicycle or the like. The vehicle is preferably a motor vehicle and / or fast motor vehicle (FKW vehicle), particularly preferably it is a motor vehicle. A typical motor vehicle or PKW body is made from a steel sheet or a plastic or a composite substrate. For example, the fenders can be made of plastic or a composite material and the main body of the body can be made of steel. When steel is used, it is first treated with an inorganic anti-rust compound, such as zinc or iron phosphate, called an E-coating, and then a primer coating is generally applied by electrodeposition. Typically, these electrodeposition primers are epoxy modified resins crosslinked with a polyisocyanate and are applied by a cathodic electrodeposition process. Optionally, a primer can be applied over the electrodeposited primer, usually by spraying, to provide better appearance and / or improved adhesion of a base coat or mono-coating to the primer.

The basecoat can also be built up without melamine. The known basecoat formulations can be used both solvent-based and aqueous. The basecoat layer can be essentially free of melamine and its derivatives. In this context, essentially free means in particular that melamine and its derivatives in the basecoat layer in amounts of less than 5% by weight, preferably less than 3% by weight, particularly preferably less than 1% by weight, based on the Total weight of the non-volatile components of the basecoat layer are present. Melamine or its derivatives present in these quantities in the basecoat layer undercut when hardened Heat supply makes no significant contribution to the crosslinking of the basecoat layer.

According to a preferred embodiment of the invention, the basecoat layer is free of melamine and its derivatives.

In embodiments where e.g. If a further improvement in the interlayer adhesion and an even higher degree of crosslinking of the basecoat film is important, it has proven to be advantageous if the basecoat film according to the invention comprises at least one NCO-reactive compound. Suitable NCO-reactive compounds for the basecoat layer are polyether polyols, polycarbonate polyols, polyester polyols, polyacrylate polyols, polyurethane polyols, polyacrylate polyols, as have already been described above for the clear lacquer layer. Preferred as the NCO-reactive compound in the basecoat layer is one or more selected from polyester polyols, polyacrylate polyols and / or

Polyurethane polyols used.

The basecoat layer can comprise at least one NCO-reactive compound.

The basecoat can be a one-component paint and have no pot life. In this context, no pot life means that the ready-to-apply basecoat is stable in storage for more than 7 days, preferably more than 2 weeks, particularly preferably more than 4 weeks, i.e. even after 7 days, 2 weeks or 4 weeks with the same properties as fresh manufactured, can be used.

In step b) the basecoat film is at least partially cured. The basecoat can be applied, for example, using the following procedure. The process includes the following process steps: The crosslinkable component of the above described coating composition of the present invention is mixed with the crosslinking component of the coating composition to form a pot mix. In general, the crosslinkable component and the crosslinking component are mixed shortly before application to form a pot mix or a mixing batch. Mixing can take place via a conventional mixing nozzle or separately in a container.

A layer of the pot mix is generally applied with a thickness in the range of about 15 microns to about 200 microns on a substrate, such as an automobile body or an automobile body, which has been precoated with an E-coating, followed by one Primer. The preceding application step can be carried out by spraying, electrostatic spraying, commercially available robot spraying systems, roller coating, dipping, flooding or brushing the pot mix or Mixed approach can be applied over the substrate. After application, the layer is allowed to evaporate, ie exposed to the air, in order to reduce the solvent content of the pot-mix or mixing batch layer, so that a "strike-in" -resistant or mix-resistant layer is produced. The period of evaporation Steps are in the range of about 5 to about 15 minutes. Then a layer of a clear lacquer composition with a thickness in the range of about 15 micrometers to about 200 micrometers can be applied by the previously described application agent via the “strike-in” resistant or mixture-resistant Layer are applied to form a multi-layer system on the substrate.

In another variant, a layer of the pot mix is generally applied with a thickness in the range from approximately 15 micrometers to approximately 200 micrometers onto a substrate, such as a motor vehicle body or a motor vehicle body, with an E-coating followed by a Primer, or a primer has been pre-coated. The preceding application step can be applied over the substrate by spraying, electrostatic spraying, commercially available robot spraying systems, roller coating, dipping, flooding or brushing the pot mix or mixing batch. The layer is allowed to evaporate after application, i.e. H. exposed to the air to reduce the solvent content of the pot-mix layer so that a strike-in-resistant layer is produced. The period of the evaporation step ranges from about 5 to about 15 minutes.

In step c), a topcoat is applied to the basecoat layer applied in step b), the topcoat being used as a structuring component and containing prepolymers containing silane groups with a content of greater than or equal to 20% by weight and less than or equal to 100% by weight on the cured top coat layer. The prepolymers used can have one or more silane groups per prepolymer. The prepolymers thus have at least one functional group consisting of a silicon backbone and hydrogen. This functional group can be, for example, -S1H ₃ . The hydrogens can also be substituted by further groups, for example alkyl or alkoxy groups. The structure of the silane-functional prepolymers which can be used according to the invention is described below.

A silane-functionalized, polymeric polyisocyanate with at least one alkoxysilane group can be provided as a silane-functional prepolymer preferred according to the invention in the context of a further embodiment. Said silane-functionalized, polymeric polyisocyanates can be synthesized by the direct reaction of polymeric polyisocyanates with alkoxysilanes which carry an isocyanate-reactive group such as amino, mercapto or hydroxy. Aromatic, araliphatic, aliphatic or cyclo aliphatic polymeric polyisocyanates with an NCO functionality> 2 are used as suitable polymeric polyisocyanates. These can also iminooxadiazinedione, isocyanurate, uretdione, urethane, Allophanate, biuret, urea, oxadiazinetrione, oxazolidinone, acylurea and / or carbodiimide structures have and can be prepared by the usual methods.

Suitable diisocyanates for the preparation of the polymeric polyisocyanates are any of the suitable and preferred diisocyanates mentioned above or any mixtures of these diisocyanates. Dimers from the aforementioned diisocyanates, trimers from the aforementioned diisocyanates or combinations thereof are very particularly preferably suitable as the inventive polymeric polyisocyanate for the preparation of the silane-functional polymeric polyisocyanates.

In a further embodiment, the silane-functional prepolymer is a silane-functional prepolymer, obtainable by reacting an isocyanatosilane with a polymer which has functional end groups which are reactive toward isocyanate groups, in particular hydroxyl groups, mercapto groups and / or amino groups.

The alkoxysilane-functional isocyanates are any compounds in which at least one, preferably exactly one, isocyanate group and at least one, preferably exactly one, silane group with at least one alkoxy substituent are present simultaneously. The alkoxysilane-functional isocyanate is also referred to below as isocyanatoalkoxysilane.

Suitable isocyanatoalkoxy silanes are, for example, isocyanatoalkylalkoxy silanes, as described, for. B. by the methods described in US 3,494,951, EP-A 0 649 850, WO 2014/063895 and WO 2016/010900 in a phosgene-free manner by thermal cleavage of the corresponding carbamates or ureas.

Preferred polymers which contain functional end groups which are reactive toward isocyanate groups are the abovementioned polymeric polyols, very particularly polyether, polyester, polycarbonate and polyacrylate polyols, and also polyurethane polyols prepared from polyisocyanates and the polyols mentioned. Mixtures of all the polyols mentioned can also be used.

According to a further preferred embodiment, at least one compound of the general formula comes as the alkoxysilane-functional isocyanate

used in which R ¹ , R ² and R ³ independently of one another for identical or different saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals having up to 18 carbon atoms, which may contain up to 3 heteroatoms from the series oxygen, sulfur , Can contain nitrogen, preferably each alkyl radicals having up to 6 carbon atoms and / or alkoxy radicals having up to 6 carbon atoms, which can contain up to 3 oxygen atoms, particularly preferably each denote methyl, methoxy and / or ethoxy, with the proviso that at least one the radicals R ¹ , R ² and R ^{3 are} connected to the silicon atom via an oxygen atom, and

X represents a linear or branched organic radical having up to 6, preferably 1 to 4 carbon atoms, particularly preferably a propylene radical (-CH2-CH2-CH2-).

Examples of such isocyanatoalkoxysilanes are isocyanatomethyltrimethoxysilane, isocyanatomethyltriethoxysilane, isocyanatomethyltriisopropoxysilane, 2-isocyanatoethyltrimethoxysilane, 2-isocyanatoethyltriethoxysilane, 2-isocyanatoethyltriisopropoxysilane, 3-

Isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropylmethyldimethoxysilane, 3-isocyanatopropylmethyldiethoxysilane, 3-isocyanatopropylethyldiethoxysilane, 3-

Isocyanatopropyldimethylethoxysilane, 3-isocyanatopropyldiisopropylethoxysilane, 3-

Isocyanatopropyltripropoxysilan, 3-Isocyanatopropyltriisopropoxysilan, 3-Isocyanatopropyl- tributoxysilane, 3-Isocyanatopropylmethyldibutoxysilan, 3-Isocyanatopropylphenyldimethoxysilan, 3-Isocyanatopropylphenyldiethoxysilan, 3-Isocyanatopropyltris (methoxyethoxyethoxy) silane, 2- Isocyanatoisopropyltrimethoxysilan, 4-Isocyanatobutyltrimethoxysilan, 4-Isocyanatobutyl- triethoxysilane, 4-Isocyanatobutyltriisopropoxysilane, 4-Isocyanatobutylmethyldimethoxysilan, 4- Isocyanatobutylmethyldiethoxysilan, 4-Isocyanatobutylethyldimethoxysilan, 4-Isocyanatobutyl- ethyldiethoxysilane, 4-Isocyanatobutyldimethylmethoxysilan, 4-Isocyanatobutylphenyldimethoxy- silane, 4-Isocyanatobutylphenyldiethoxysilan, 4-isocyanato (3-methylbutyl) trimethoxysilane, 4-isocyanato (3-methylbutyl) triethoxysilane, 4-isocyanato (3-methylbutyl) methyldimethoxysilane, 4-

Isocyanato (3-methylbutyl) methyldiethoxysilane and 11-isocyanatoundecyltrimethoxysilane or any mixture of such isocyanatoalkoxysilanes.

Suitable isocyanatoalkoxysilanes are, for example, isocyanatosilanes with a thiourethane structure, such as those obtained by the process of WO 2014/037279 by reacting any aliphatic, cycloaliphatic, araliphatic or aromatic diisocyanates with any mercaptosilanes in an NCO: SH ratio of 6: 1 to 40: 1 and subsequent Removal of excess, unreacted monomeric diisocyanates can be obtained by thin film distillation.

According to a further preferred embodiment, at least as isocyanatoalkoxysilane a compound according to the general formula for use

which are present in a mixture with minor amounts of the corresponding bis adduct, in which both isocyanate groups of the diisocyanate are reacted with the mercaptosilane, in formula (III) and the bis adduct

R ¹ , R ² and R ³ independently of one another for identical or different saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals having up to 18 carbon atoms, which may contain up to 3 heteroatoms from the series oxygen, Can contain sulfur, nitrogen, preferably each alkyl radicals with up to 6 carbon atoms and / or alkoxy radicals with up to 6 carbon atoms, which can contain up to 3 oxygen atoms, particularly preferably each denote methyl, methoxy and / or ethoxy, with the proviso that at least one of the radicals R ¹ , R ² and R ^{3 is} connected to the silicon atom via an oxygen atom, X for a linear or branched organic radical having up to 6, preferably 1 to 4 carbon atoms, particularly preferably for a propylene radical (-CH2-CH2- CH2-) stands and

Y represents a linear, branched, or cyclic organic radical. This can be an aromatic or aliphatic radical, preferably a unit or a mixture selected from the group consisting of isophoronyl, pentamethylene, hexamethylene, biscylohexylmethylene, toluidenyl or methylene diphenylene.

The isocyanatosilanes of the formula (III) can preferably be mixed with polyols to form prepolymers containing silane groups according to the general formula

implement, in the formula (IV) R ¹ , R ² and R ³ independently of one another for identical or different saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals having up to 18 carbon atoms, which may contain up to 3 heteroatoms from the series oxygen, sulfur , Can contain nitrogen, preferably each alkyl radicals having up to 6 carbon atoms and / or alkoxy radicals having up to 6 carbon atoms, which can contain up to 3 oxygen atoms, particularly preferably each denote methyl, methoxy and / or ethoxy, with the proviso that at least one the radicals R ¹ , R ² and R ^{3 are} connected to the silicon atom via an oxygen atom,

X represents a linear or branched organic radical having up to 6, preferably 1 to 4 carbon atoms, particularly preferably a propylene radical (-CH2-CH2-CH2-) and

Y represents a linear, branched, or cyclic organic radical. This can be an aromatic or aliphatic radical, preferably a unit or a mixture selected from the group consisting of isophoronyl, pentamethylene, hexamethylene, biscylohexylmethylene, toluidenyl or methylene diphenylene,

Z stands for a structural unit which is derived from an at least difunctional polyol which has a number average molecular weight M _n of 270 to 22000 g / mol, preferably 500 to 18000 g / mol and particularly preferably 800 to 12000 g / mol. The polyol preferably additionally has an acid number, determined according to DIN EN ISO 2114: 2002-06, of 0.01 to 30.0 mg KOH / g, preferably 0.1 to 25.0 mg KOH / g, particularly preferably 0.2 to 20 .0 mg KOH / g, based in each case on the solids content of the polyol. The polyol is particularly preferably a polyester polyol, polycarbonate polyol and / or polyacrylate polyol, preferably with an average OH functionality of 2 to 6 and particularly preferably 2 to 4. Suitable and preferred polyols from which the structural unit Z in the formula (IV) is derived , are the (polymeric) polyols already described above, whereby the same preferences apply. Such suitable and preferred polyols and silane-functional prepolymers obtained therefrom are the compounds disclosed in WO 2018/029197, which can preferably be prepared by the processes described there. Alternatively or in combination to the above definition of Z in the formula (IV), according to a further embodiment of the process according to the invention, Z represents a structural unit which is derived from a polyhydric alcohol and / or ether or ester alcohol as polyol, which has 2 to 14 carbon atoms , preferably contains 4 to 10 carbon atoms. As an alternative or in combination to the above definition of Z in formula (IV), suitable polyols, also referred to as low molecular weight, polyhydric alcohols and / or ethers or ester alcohols, such as, for example, 1,2-ethanediol, 1,2- and 1,3-propanediol, are , the isomeric butanediols, pentanediols, hexanediols, heptanediols and octanediols, 1,10-decanediol, 1,12-dodecanediol, 1,2- and 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, l, 4-bis (2- hydroxyethoxy) benzene, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (4-hydroxycyclohexyl) propane (perhydrobisphenol), 1,2,3-propanetriol, 1, 2,4-butanetriol, 1,1,1-trimethylolethane, 1,2, 6-hexanetriol, 1,1,1-trimethylolpropane (TMP), bis (2-hydroxyethyl) hydroquinone, 1,2,4- and 1,3,5-trihydroxycyclohexane, 1,3,5-tris (2-hydroxyethyl) isocyanurate, bis (hydroxymethyl) tricyclo [5.2.1.0 ²⁶ ] decane, 4,8-bis (hydroxymethyl) tricyclo- [5.2 .1.0 ^2,6 ] -decane and 5,8- bis (hydroxymethyl) -tricyclo- [5.2.1.0 '] containing Jdecan, the compounds being individual or can be present in a mixture of isomers., Di-trimethylolpropane, 2,2-bis (hydroxymethyl) -l, 3-propanediol (pentaerythritol), 2,2,6,6-tetrakis (hydroxymethyl) -4-oxa-heptane-l, 7-diol (dipentaerythritol), mannitol or sorbitol, low molecular weight ether alcohols, such as. B. diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol or dibutylene glycol or low molecular weight ester alcohols, such as. B. Hydroxypivalinsaureneopentylglycolester.

Preferred examples of such isocyanatosilanes with a thiourethane structure are the reaction products of 2-mercaptoethyltrimethoxylsilane, 2-mercaptoethylmethyldimethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-mercaptopropylmethyldimethoxysaptopylane, 3

Mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-mercapto-propylethyldimethoxysilane, 3-mercaptopropylethyldiethoxysilane and / or 4-mercaptobutyltrimethoxysilane with 1,5-diisocyanatopentane, 1,6-diisocyanatoethylhexane, l-diisocyanatoethylhexane, l isocyanatomethylcyclohexane, 2,4'- and / or 4,4'-diisocyanatodicyclohexylmethane or any mixture of these diisocyanates.

Particularly preferred alkoxysilane-functional isocyanates for the process according to the invention are isocyanatomethyltrimethoxysilane, isocyanatomethyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane, which are prepared by the process of WO 2014/037279 by reacting 3-mercaptopropyltrimethoxysiloxiloxysiloxiloxysiloxysilane with 1-mercapto-tranethoxysiloxysilane / 1-mercapto-tranethoxysiloxysilane / 3-mercapto-tranethoxysiloxysilane / 3-mercapto-tranethoxysiloxysilane and / or 3-mercaptopropyltrimethoxysiloxysilane , 5-diisocyanatopentane, 1,6-diisocyanatohexane, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 2,4'- and / or 4,4'-diisocyanatodicyclohexylmethane available isocyanatosilanes with thiourethane structure and any mixtures of such isocyanatosilanes .

The use of the isocyanatosilanes mentioned with a thiourethane structure is very particularly preferred. In order to obtain the silane-functional prepolymers suitable for the present invention, as in the process described in WO 2018/029197, after the reaction, preferably after the reaction of the at least one polymeric polyol or low molecular weight polyol described above, or a mixture of both, with the at least one above, reacted the reaction product obtained in a further process step with at least one alkoxysilane-functional isocyanate. The reaction product obtained can optionally be subjected to any further intermediate steps before the reaction with the alkoxysilane-functional isocyanate, provided that a sufficient amount of hydroxyl groups is still present in the reaction product during the reaction with the at least one alkoxysilane-functional isocyanate. However, the reaction product with the alkoxysilane-functional isocyanate is particularly preferably reacted without intermediate steps.

Also suitable isocyanatoalkoxysilanes are, for example, those with a formylurea structure, such as can be obtained by the process of WO 2015/113923 by reacting silanes containing formamide groups with molar excess amounts of any aliphatic, cycloaliphatic, araliphatic or aromatic diisocyanates and subsequent removal of unreacted monomeric diisocyanates by distillation.

According to a further preferred embodiment, at least one compound of the general formula (V) is used as the isocyanatoalkoxysilane

which are mixed with minor amounts of silane-functional compounds of the general formula (VI)

are present, in the formulas (V) and (VI) R ¹ , R ² and R ³ independently of one another for identical or different saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals having up to 18 carbon atoms which can optionally contain up to 3 heteroatoms from the series oxygen, sulfur, nitrogen, preferably each Alkyl radicals with up to 6 carbon atoms and / or alkoxy radicals with up to 6 carbon atoms, which can contain up to 3 oxygen atoms, particularly preferably each denote methyl, methoxy and / or ethoxy, with the proviso that at least one of the radicals R ¹ , R ² and R ^{3 is} connected to the silicon atom via an oxygen atom, X represents a linear or branched organic radical having up to 6, preferably 1 to 4 carbon atoms, particularly preferably a propylene radical (-CH2-CH2-CH2-) and

Y represents a linear or branched, aliphatic or cycloaliphatic radical having 4 to 18 carbon atoms or an optionally substituted aromatic or araliphatic radical having 6 to 18 carbon atoms, preferably a linear or branched, aliphatic or cycloaliphatic radical having 6 to 13 carbon atoms, and

W independently of one another represents a formyl or acetyl group or also a COO group with a radical G. G can be mono-, di-, tri- or tetrafunctional and stands for a linear or branched, aliphatic or cycloaliphatic radical or a connecting unit derived therefrom having 4 to 18 carbon atoms or an optionally substituted aromatic or araliphatic radical or a derivative thereof connecting unit with 6 to 18 carbon atoms, preferably for a linear or branched, aliphatic or cyclolaliphatic radical with 6 to 13 carbon atoms. The radical W can optionally contain one or more heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen.

Examples of such isocyanatosilanes with a formylurea structure are the reaction products of formamide silanes, as are obtained, for example, by the process disclosed in WO 2015/113923 by reacting amino silanes carrying primary amino groups, in particular 3-aminopropyltrimethoxysilane and / or 3-aminopropyltriethoxysilane, with methyl formate and preferably with methyl formates / or ethyl formate, obtained with elimination of alcohol, with aliphatic and / or cycloaliphatic diisocyanates, preferably 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 2,4 ' - And / or 4,4'-diisocyanatodicyclohexylmethane or any mixtures of these diisocyanates.

It is further preferred to use at least one N-formylaminoalkylsilane of the formula (IX) as an isocyanate-reactive alkoxysilane component for the synthesis of prepolymers containing alkoxysilyl groups

in which R ¹ denotes an at least divalent, optionally substituted, linear or branched, aliphatic, alicyclic, araliphatic and / or aromatic structural unit having 1 to 12 carbon atoms, in which one or more non-adjacent methylene groups can be replaced by O or S,

R ² and R ³ each independently represent a linear or branched, aliphatic

Group having 1 to 12 carbon atoms, which can be substituted, and n represents the number 0, 1 or 2. Preferred compounds of the formula (IX) are selected from N- (3-

Triethoxysilylpropyl) formamide, N- (3-methyldiethoxysilylpropyl) formamide, N- (3-trimethoxysilylpropyl) formamide, N- (3-methyldiethoxymethylsilylpropyl) formamide, or mixtures thereof. Corresponding compounds and resulting prepolymers containing alkoxysilyl groups are disclosed in US 2016/340372 A1, to which reference is made expressly and in full.

Other suitable isocyanatoalkoxysilanes are, for example, the 1: 1 monoadducts of diisocyanates and special secondary aminoalkylalkoxysilanes prepared by the process of EP-A 1 136 495, the aspartic acid esters obtainable from EP-A 0 596 360 and obtainable by reacting maleic dialkyl esters with aminosilanes, in which the reactants are reacted with one another using a large molar excess of isocyanate and the unconverted monomeric diisocyanates are subsequently separated off by distillation.

Furthermore, aspartic acid esters as described in EP-A-0 596 360 are preferably used as isocyanate-reactive compounds. With these molecules of the general formula (VIII)

X means identical or different alkoxy or alkyl radicals, which can also be bridged, but at least one alkoxy radical must be present on each Si atom, Q is a difunctional linear or branched aliphatic radical and Z represents an alkoxy radical with 1 to 10 carbon atoms. The use of such aspartic acid esters is preferred. Examples of particularly preferred aspartic acid esters are diethyl N- (3-triethoxysilylpropyljaspartate, diethyl N- (3-tri-methoxysilylpropyl) diethyl and N- (3-dimethoxymethylsilylpropyl) -diethyl aspartate (3- preferred is the use of diethyl diester). Triethoxysilylpropyl) aspartic acid diethyl ester Corresponding prepolymers A) prepared from compounds of the formula (VIII) are those as described and prepared in EP-A-0 994 117.

The alkoxysilyl-functionalized prepolymers of the publication EP 2 641 925 A and the publication DE 10 2012 204290 A are also preferably suitable in the context of this invention. The silane-functionalized thioallophanates of publication WO 2015/189164 are particularly preferably usable isocyanate-functional silanes of the formula (VII)

wherein

R ¹ , R ² and R ³ independently of one another represent identical or different radicals and each represent a saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or an optionally substituted aromatic or araliphatic radical with up to 18 carbon atoms, which can optionally contain up to 3 heteroatoms from the series oxygen, sulfur, nitrogen,

X represents a linear or branched organic radical with at least 2 carbon atoms,

Y is a linear or branched, aliphatic or cycloaliphatic, an araliphatic or aromatic radical having up to 18 carbon atoms and n is an integer from 1 to 20.

These are preferably reacted with at least one polyol to obtain a silane-functional prepolymer. The polyols mentioned above are preferred as polyols (vide supra). The reaction of the isocyanatosilanes, as exemplified in formulas (II), (III), (V) and (VII), with the isocyanate-reactive groups, with the polyols preferably used, is carried out in the same manner as above for the preparation of the isocyanate -containing prepolymer from the polyisocyanate component with the polyol component described.

Suitable and preferred polyols, from which the structural unit Z in the formula (IV) is derived, are the (polymeric) polyols already described above, the same preferences apply. Such suitable and preferred polyols and silane-functional prepolymers obtained therefrom are the compounds disclosed in WO 2018/029197, which can preferably be prepared by the processes described there.

Alternatively or in combination to the above definition of Z in the formula (IV), according to a further embodiment of the process according to the invention, Z represents a structural unit which is derived from a polyhydric alcohol and / or ether or ester alcohol as polyol, which has 2 to 14 carbon atoms , preferably contains 4 to 10 carbon atoms.

As an alternative or in combination to the above definition of Z in formula (IV), suitable polyols, also referred to as low molecular weight, polyhydric alcohols and / or ether or ester alcohols such as, for example, 1,2-ethanediol, 1,2- and 1,3- Propanediol, the isomeric butanediols, pentanediols, hexanediols, heptanediols and octanediols, 1,10-decanediol, 1,12-dodecanediol, 1,2- and 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-bis (2nd -hydroxyethoxy) - benzene, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (4-hydroxycyclohexyl) propane (perhydrobisphenol), 1,2,3-propanetriol, 1 , 2,4-butanetriol, 1,1,1-trimethylolethane, 1,2,6-hexanetriol, 1,1,1-trimethylolpropane (TMP), bis- (2-hydroxyethyl) -hydroquinone, 1,2,4- and 1,3,5-trihydroxycyclohexane, 1,3,5-tris (2-hydroxyethyl) isocyanurate, bis (hydroxymethyl) tricyclo [5.2.1.0 ²⁶ ] decane, 4,8-bis (hydroxymethyl) tricyclo- [ 5.2.1.0 ^2,6 ] -decane and 5.8- Bis (hydroxymethyl) -tricyclo- [5.2.1.0 '] containing Jdecan, where the compounds can be present individually or in an isomer mixture., Di-trimethylolpropane, 2,2-bis (hydroxymethyl) -l, 3-propanediol (pentaerythritol), 2,2,6,6-tetrakis (hydroxymethyl) -4-oxa-heptane-l, 7-diol (dipentaerythritol), mannitol or sorbitol, low molecular weight ether alcohols, such as, for. B. diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol or dibutylene glycol or low molecular weight ester alcohols, such as. B. Hydroxypivalinsaureneopentylglycolester.

The reaction of the isocyanatosilane of the formula (V) is preferred first with a monofunctional alcohol such as methanol, ethanol, propan-1-ol, propan-2-ol, 1-butanol, 2-butanol, 1-pentanol, 1-hexanol, 1 -Heptanol, ethyl-2-hexanol, 1-octanol, 1-nonanol and 1-decanol. The reaction takes place to at least 50% by weight of the NCO groups of the isocyanatosilane (V), particularly preferably with up to 60% by weight and very particularly preferably with up to 70% of the monofunctional alcohol.

The ratio of the NCO groups of the isocyanatosilane to the isocyanate-reactive groups, preferably the hydroxyl groups of the polyols, is between 0.5: 1 and 1: 1, preferably between 0.75: 1 and 1: 1, very particularly preferably between 0.9: 1 and 1: 1.

As described in the patents US 2017/0369626, US 2017/0369627 and US 2017/0369631, silane group-containing monoisocyanates can also be obtained by reacting isocyantosilanes with amino, hydroxyl and mercapto-functional units and then allophanating them with an excess of the diisocyanates described above being represented.

Suitable isocyanatosilanes or isocyanate-functional alkoxysilane compounds are in principle any monoisocyanates containing alkoxysilane groups with a molecular weight of 145 g / mol to 800 g / mol. Examples of such compounds are isocyanatomethyltrimethoxysilane, isocyanatomethyltriethoxysilane, (isocyanatomethyl) methyldimethoxysilane, (isocyanatomethyl) - methyldiethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropylmethyldimethoxysilanopropyloxysilane, 3-isiethoxysiloxaneyl 3-isocyanyloxysilane. The use of 3-isocyanatopropyltrimethoxysilane or 3-isocyanatopropyltriethoxysilane is preferred here, and the use of 3-isocyanatopropyltrimethoxysilane is very particularly preferred. However, isocyanate-functional alkoxysilane compounds with a higher molecular weight can also be used. It is possible according to the invention to use isocyanate-functional silanes which have been prepared by reacting a diisocyanate with an amino or thiosilane, as are described in US Pat. No. 4,146,585 or EP-A 1 136 495. Suitable solvents are in particular those which are inert towards the reactive groups of the isocyanatosilanes, for example the known customary aprotic paint solvents, such as. B. ethyl acetate, butyl acetate, ethylene glycol monomethyl or ethyl ether acetate, 1-methoxypropyl-2-acetate, 3-methoxy-n-butyl acetate, acetone, 2-butanone, 4-methyl-2-pentanone, cyclohexanone, toluene, Xylene, chlorobenzene, white spirit, more highly substituted aromatics, such as those sold under the names Solventnaphtha, Solvesso, Isopar, Nappar (Deutsche EXXON CHEMICAL GmbH, Cologne, DE) and Shellsol (Deutsche Shell Chemie GmbH, Eschborn, DE), for example, but also solvents such as propylene glycol diacetate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl and butyl ether acetate, ethyl ethoxypropionate, propylene carbonate, N-methylpyrrolidone and N-methylcaprolactam, or any mixture of such solvents.

In a further embodiment, the silane-functional polymer is a silane-functional polymer which can be obtained by a hydrosilylation reaction of polymers with terminal double bonds, for example poly (meth) acrylate polymers and polyether polymers, in particular of allyl-terminated polyoxyalkylene polymers, described for example in US Pat. No. 3,071,751 and US Pat. No. 6,207,766.

In all of the isocyanate-reactive silane components mentioned, depending on the desired field of application, the methoxy derivatives and ethoxysilane derivatives are preferred for use in corrosion protection and in the automotive refinish sector. The prepolymers containing alkoxysilyl groups which can be used according to the invention are prepared using isocyanate-reactive alkoxysilane compounds by reacting isocyanate-functional prepolymer (preferably isocyanate-functional polyurethane or polymeric polyisocyanates) by reaction with an isocyanate-reactive alkoxysilane compound (in particular the aforementioned preferred isocyanate-reactive alkoxysilane compounds) to give the silane-terminated prepolymer. Said reaction with isocyanate-reactive alkoxysilanes takes place within a temperature range from 0 ° C. to 150 ° C., preferably from 20 ° C. to 120 ° C., the proportions generally being chosen such that 0.8 to 1 per mole of NCO groups used , 3 moles of the isocyanate-reactive alkoxysilane compound are used, preferably 1.0 mole of isocyanate-reactive alkoxysilane compound per mole of NCO groups used. The at least one topcoat layer can be applied to the substrate from solution, dispersion in a liquid dispersant such as water or from the melt and, in the case of powder coatings, in solid form. Application from solution is preferred. Suitable methods of application are, for example, printing, brushing, rolling, pouring, dipping, fluidized bed processes and / or preferably spraying such as, for example, compressed air spraying, airless Spraying, high rotation, electrostatic spray application (ESTA), possibly combined with hot spray application such as hot air hot spraying.

The number of basecoat and topcoat layers to be applied is not limited to one layer. It is also possible to apply two, three, four or more layers of basecoat. It is also possible to apply two, three, four or more clear and / or topcoat layers, as long as at least one basecoat layer according to the invention is in contact with a topcoat layer according to the invention.

In order to facilitate the application of the basecoat and the clear and / or topcoat layer, if necessary, the NCO-reactive compound and / or the polyisocyanate can be present in a suitable solvent, for example. Suitable solvents are those which have sufficient solubility of the NCO-reactive compound and / or the polyisocyanate and are free from groups which are reactive toward isocyanates. Examples of such solvents are acetone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, methyl isoamyl ketone, diisobutyl ketone, ethyl acetate, n-butyl acetate, ethylene glycol diacetate, butyrolactone, diethyl carbonate, propylene carbonate, ethylene carbonate, N, N-dimethylformamide, N, N-dimethylacetamide, and -Ethylpyrrolidone, methylal, ethylal, butylal, 1,3-dioxolane, glycerol formal, benzene, toluene, n-hexane, cyclohexane, solvent naphtha, 2-methoxypropyl acetate (MPA). In addition, the NCO-reactive compound can also be present in solvents which carry groups which are reactive toward isocyanates. Examples of such reactive solvents are those which have an average functionality of isocyanate-reactive groups of at least 1.8. These can be, for example, low-molecular diols (for example 1,2-ethanediol, 1,3- or 1,2-propanediol, 1,4-butanediol), triols (for example glycerol, trimethylolpropane), but also low-molecular diamines, for example polyaspartic acid esters, be.

After the application of the at least one basecoat layer and before the application of the at least one clearcoat or topcoat layer, it is possible to wait until a film is formed and any solvent and / or water present has largely left the film. Depending on the application and drying device available, the optimal waiting time can be determined in simple tests. The film formation and leaving the film of solvent and / or water should have progressed to such an extent that the applied clearcoat or topcoat no longer leads to genuine dissolving and a change in the appearance of the basecoat. In particular in the case of metallic effect basecoats, the alignment of the metallic effect pigments can be disturbed by the application of a clear coat too early and therefore can lead to a reduction in the flip-flop effect and / or to graying. If the drying or hardening of the basecoat has progressed too far, the hardener can diffuse more poorly into the basecoat. The topcoat layer has a catalyst with a content of greater than or equal to 0.01% by weight and less than or equal to 5% by weight, based on the cured topcoat layer, and the catalyst is selected from the group consisting of protonic acids or mixtures thereof. The content of the catalyst in the composition of the topcoat layer can be determined using quantitative FTIR. Suitable protonic acids are organic and inorganic protonic acids, the acid having one or more acidic H atoms.

Suitable protonic acids can generally be selected from the group consisting of acetic acid, trifluoroacetic acid, sulfuric acid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, hydroxyethylsulfonic acid, hydroxypropylsulfonic acid, 1,3-propanedisulfonic acid, methylamidosulfonic acid, sulfoacetic acid, 4-bromobenzenesulfonic acid, 4-

Chlorobenzenesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, 4-hydroxybenzene sulfonic acid, 4-ethylbenzene sulfonic acid, 2-Mesithylensulfonsäure, 1-naphthalenesulfonic acid, 1,5- naphthalenedisulfonic acid, 2,6-naphthalenedisulfonic acid, 2-hydroxy-2-naphthalenesulfonic acid, trifluoromethanesulfonic acid, substituted phosphonic diesters and diphosphonic diesters , preferably from the group consisting of acyclic phosphonic diesters, cyclic phosphonic diesters, acyclic diphosphonic diesters and cyclic diphosphonic diesters. Such catalysts are described for example in German patent application DE-A-102005045228. Phosphoric acid types (e.g. Nacure types from King Industries, e.g. Nacure 4000), such as Methyl phosphate, ethyl phosphate, n-propyl phosphate, isopropyl phosphate, butyl phosphate, 2-ethylhexyl phosphate, phenyl phosphate,

Dimethyl phosphate, diethyl phosphate, tri-n-propyl phosphate, diisopropyl phosphate, dibutyl phosphate, bis (2-ethylhexyl) phosphate, diphenyl phosphate, methylene diphosphonic acid,

Dimethylphosphonic acid, ethylphosphonic acid, tert-butylphosphonic acid, benzenephosphonic acid, octylphosphonic acid, octane diphosphonic acid, dibenzenephosphonic acid, benzenephosphinic acid, diisooctylphosphinic acid, 6-phosphonohexanoic acid, nitrilotris (methylene) trisphosphonic acid,

Diphenyl phosphite and mixtures thereof. To clarify, it should be noted that amine-blocked and amine-neutralized derivatives of substituted or unsubstituted phosphoric acid are not catalysts according to the invention.

In step d), the layer applied in step c) is reacted to obtain the top coat layer. As a function of the prepolymers containing silane groups, the reaction takes place in the top coat layer while increasing the molecular weight of the prepolymers used containing silane groups. This can be done, for example, by removing the solvent within a wet process or by inducing chemical crosslinking of the prepolymers with one another by means of further substances or compounds. The presence of the catalysts according to the invention can usually be used for crosslinking be enough. Special conditions for obtaining the top coat layer according to the invention were discussed above, for example, in connection with the usable prepolymers containing silane groups.

In a preferred embodiment of the process, the prepolymers containing silane groups in step c) can be silane-terminated prepolymers. In particular, the use of silane-terminated propolymers can contribute to preferred drying and curing kinetics of the top coat layer. In addition to preferred kinetics, these connections in particular also show preferred mechanical properties, such as, for example, particularly elastic behavior and good pendulum hardness. Without being bound by theory, this can probably be attributed to the preferred end-to-end orientation of the prepolymers in the crosslinking process, with the formation of particularly long intermediate chains.

In a preferred aspect of the process, the prepolymers containing silane groups in step c) can be silane-terminated polyurethanes. The silane-terminated polyurethanes in particular have proven suitable for use as prepolymers containing silane groups. This group of prepolymers is characterized by particularly fast and efficient drying kinetics and provides visually appealing top coats. The topcoat layers made from these prepolymers can in particular also be clearcoat layers which only negligibly impair the color properties of the basecoat layer. Silane-terminated polyurethanes are distinguished by the fact that they are a reaction product of an isocyanatosilane with a short-chain alcohol, polyester polyol, polycarbonate polyol, polyacrylate polyol or a mixture.

Suitable silane-terminated prepolymers have already been described above, but particularly suitable compounds can be the reaction products of an isocyanatosilane containing a thiourethane structure with a short-chain alcohol, polyacrylate polyol or a mixture thereof.

In the context of a further preferred aspect of the layer composite, the prepolymers containing silane groups and / or their crosslinking products, for the production of which isocyanate functionalities are used, have an NCO residual content determined according to DIN EN ISO 11909: 2007-05 of greater than or equal to 0.0005% and less than or equal to 1%. In a preferred embodiment of the method, the catalyst can be a polybasic protonic acid. The polybasic protonic acids in particular have proven to be very suitable for the formation of very stable and solvent-resistant layer composites. Polybasic protonic acids are acids with more than one acidic group, in particular more than one acidic hydrogen atom, which can react as part of an acid-base reaction. In this In particular, the polybasic inorganic protonic acids, such as sulfuric or phosphoric acid, are particularly suitable. Without being bound by theory, the high tendency of the free protons to diffuse can cause some of the protons to diffuse / migrate into the boundary layer between the base and topcoat layers and lead to an increased adhesion of the two layers to one another. Such a diffusion process cannot take place to such an extent in the case of larger catalysts, such as Lewis acids, for example, that the polybasic protonic acids can be used with preference. In general, the polybasic protonic acids can be selected from the group consisting of phosphoric acids, phosphonic acids, phosphinic acids or their derivatives, sulfuric acid, sulfurous acid and mixtures thereof.

In a further embodiment of the method, the catalyst can be a polybasic protonic acid with a pKa value of greater than or equal to -14.0 and less than or equal to 4.0. In the case of polybasic protonic acids, the pKs value given in the context of the present invention relates to the first pKs value. Protonic acids of the acid strength given above have proven to be particularly suitable for achieving particularly rapid drying kinetics of the entire paint composite. The equilibrium and thus the catalytic effect is established very quickly and very uniform topcoat layers can be obtained as a result. Suitable catalysts from the range given above are, for example, dibutyl phosphate, diphenyl phosphate, bis (2-ethylhexyl phosphate), benzene phosphonic acid and benzene phosphinic acid. In a preferred aspect of the process, the catalyst can be a substituted or unsubstituted phosphoric acid. Phosphoric acid in particular has proven to be suitable for obtaining very fast drying kinetics and stable layer structures, which are particularly very solvent-resistant. Without being bound by theory, this is attributed to special interactions of the phosphates obtainable after the proton has been split off with the silane groups of the prepolymer. A substituted phosphoric acid can generally be a phosphoric acid in which one or more OH groups have been replaced by C1-C30 organic radicals or H atoms or mixtures thereof. These organic radicals can also carry further functional groups, such as, for example, -OH or -NCO groups.

In a preferred characteristic of the process, the catalyst can be selected from the group consisting of phosphoric acid and C 1 -C 5 alkyl, aryl, cycloalkyl-substituted phosphoric acid or mixtures thereof. In addition to the phosphoric acid as such, the pure hydrocarbon-substituted phosphoric acids in particular have proven to be suitable catalysts. By using these acids, particularly homogeneous layers with suitable optical properties, such as transparency and turbidity, can be obtained. In a preferred embodiment of the process, the catalyst in step c) can be used in a concentration of greater than or equal to 0.03% by weight and less than or equal to 3% by weight. This catalyst concentration is, as defined above, indicated on the entire top coat layer available. These concentrations can contribute to economically justifiable curing speeds and a very homogeneous layer structure. Smaller concentrations can be disadvantageous since the layers then harden very slowly and / or the required layer hardness is not achieved. Higher concentrations can be disadvantageous because the layer does not harden in an equilibrium but inhomogeneously due to a too high reaction rate. Preferred catalyst concentrations also have a concentration of greater than or equal to 0.1% by weight and less than or equal to 2.5% by weight, furthermore preferably at concentrations of greater than or equal to 0.5% by weight and less than or equal to 2% by weight.

In a preferred aspect of the process, the silane-terminated polyurethanes can have a residual NCO content, determined in accordance with DIN EN ISO 11909: 2007-05, of greater than or equal to 0.0005% and less than or equal to 1%. The use of silane groups

Prepolymers and in particular silane-terminated polyurethanes with a low proportion of NCO groups can lead to particularly well-adhering and uniform layer composites. Without being bound by theory, this can mean that the proportion of NCO side reactions with the catalyst and / or the other prepolymers is so small that they are no longer reflected in the end result of the cured layer. In this way, visually particularly appealing layer composites can be obtained.

In a preferred embodiment of the method, the silane-terminated polyurethanes can have a viscosity, determined in accordance with DIN EN ISO 3219: 1994-08, of greater than or equal to 50 mPas and less than or equal to 5000 mPas. The concentration of silane-terminated polyurethanes for determining the viscosity value can be 60% by weight. These viscosities have proven to be suitable for obtaining stable topcoat layers. Higher viscosities can lead to inhomogeneous layer build-up, while lower viscosities can only contribute to insufficient mechanical properties. Preferred viscosity ranges can also be greater than or equal to 200 mPas and less than or equal to 3000 mPas and greater than or equal to 500 mPas and less than or equal to 2000 mPas.

Furthermore, according to the invention, a layer composite of a lower basecoat and a topcoat layer arranged above it, the lower basecoat layer is selected from the group consisting of polyacrylates, polyurethanes, polyether polyols, polycarbonate polyols, polyester polyols, melamine resins, alkyd resins or mixtures thereof, and the upper topcoat layer contains crosslinked silane groups. containing polymers and protonic acids or Contains mixtures thereof. In particular, the combination, the layer composite of the base coat layer which can be replaced according to the invention and the top coat layer which can be used according to the invention, can be distinguished by improved solvent resistance, higher mechanical hardness and improved layer adhesion. For further advantages of the layer composite according to the invention, reference is made explicitly to the explanations regarding the method according to the invention.

In a further embodiment of the layer composite, the polybasic protonic acids can be selected from the group consisting of phosphoric acid, C1-C15 alkyl, aryl, cycloalkyl-substituted phosphoric acids or mixtures thereof. For further advantages of the layer composite according to the invention, reference is made explicitly to the explanations regarding the method according to the invention.

In a further embodiment of the layer composite, the upper topcoat layer with a layer thickness of 50 pm on a white basecoat can have a Delta Lab value in relation to the white basecoat of AL greater than or equal to 0.2 and less than or equal to 20, of Aa greater than or equal - 0.01 and less than or equal to -20, and Ab greater than or equal to -0.01 and less than or equal to -13, which was determined in accordance with DIN EN ISO 1166-4: 2012-06. In particular, clear topcoats, that is to say clearcoats, which have little or no impairment of the optical properties, in particular the color, of basecoat layers can be obtained by means of the process according to the invention. Very homogeneous and transparent topcoat layers can thus be obtained.

In a further preferred embodiment, the top coat layer at a layer thickness of 50 pm can have a total transmission according to ISO 14782: 1999-08 / ASTM D1003: 2013-11 of greater than or equal to 85% and less than or equal to 99.5% and a turbidity of greater or equal to 0.5 and less than or equal to 15. This layer may further preferably have an image sharpness of greater than or equal to 90 and less than or equal to 99.8. The structure according to the invention enables optically high-quality layer composites to be obtained, in particular the topcoat layer being highly transparent and not very light-scattering. This can contribute to a color impression of the lower lacquer layer that is as pristine as possible.

In a further embodiment of the layer composite, the upper topcoat layer with a layer thickness of 50 pm has a glossy haze measured according to DIN EN ISO 13803: 2015-02 of greater than or equal to 2 and less than or equal to 30. The structure according to the invention can also be used to achieve, in particular, very shiny layer composites which have a brilliant appearance. These coatings are very suitable for the automotive sector, for example. In a preferred embodiment of the layer composite, the upper topcoat layer can have a pendulum hardness, determined in accordance with DIN EN ISO 1522: 2000-09, of greater than or equal to 50 s and less than or equal to 180 s. Layer composites with special viscoelastic properties can be obtained by means of the method according to the invention. In particular, the top coat layer according to the invention can contribute to providing highly elastic layer composites which are suitable for the entire layer

Use properties can lead. The improved elasticity can, for example, help to reduce the proportion of lacquer chips due to mechanical loads, such as stone chips. In a preferred embodiment, the catalysts used in the topcoat layer can form a concentration gradient in the basecoat. This means that the catalyst of the top coat layer can diffuse into the basecoat and the concentration of these components in the basecoat layer is not constant, but that the concentration of this component is lower at the lower limit of the basecoat layer and then rises over the basecoat layer to the topcoat layer. This training can contribute to a particularly firm adhesion of both layers.

Furthermore, the use of the layer composite according to the invention for coating a substrate is according to the invention. Regarding the advantages of the use according to the invention, reference is made explicitly to the advantages of the method according to the invention and the advantages of the layer composite according to the invention.

Furthermore, according to the invention, a vehicle or a vehicle body part has a layer composite according to the invention. The vehicle or the vehicle body part can be constructed from one or more materials. Suitable materials are, for example, metal, plastic or their mixtures. The vehicle can be any vehicle known to those skilled in the art. For example, the vehicle can be a motor vehicle, fast motor vehicle, motorcycle, scooter, bicycle or the like. The layered composite according to the invention is particularly suitable in the field of the production of automotive coatings, since here the elastic properties and improved weather resistance are particularly in demand. Furthermore, the high optical transparency of the top coat layer allows the color impression of a basecoat layer to be obtained particularly well. The vehicle is preferably a motor vehicle and / or fast motor vehicle (FKW vehicle), particularly preferably it is a motor vehicle. Examples

General measurement methodology

Unless stated otherwise, the percentages relate to the weight.

The tests were carried out at 23 ° C and 50% relative humidity. The NCO contents were determined titrimetrically in accordance with DIN EN ISO 11909: 2007-05.

OH numbers were determined titrimetrically according to DIN 53240-2: 2007-11. The stated OH contents were calculated from the analytically determined OH numbers.

In order to determine the pot life, it was not the doubling of the run-out times, usually determined in accordance with DIN EN ISO 2431: 2011-11 (“Determination of the run-out time with outlet cups”), that was used, but the skin formation time of the moisture-curing STP. By periodically touching the film surface with the end of a wooden spatula, the point in time at which the spatula tip adhering skin can be pulled up from the surface was determined.

The drying times (TI, T3 and T4) were determined in accordance with DIN EN ISO 9117-5: 2010-07 (drying test part 5: modified Bandow-Wolff method). The solvent and water resistance were determined according to DIN EN ISO 4628-1: 2016-07. For the test of solvent resistance, the solvents xylene, hereinafter also abbreviated as "Xy", methoxypropylacetate (MPA), ethyl acetate (EA) and acetone (Ac) were used. The contact time was 5 minutes in each case. For the measurement of water resistance, the contact time was 24 hours in each case. The sampling was carried out according to the listed standard. The test area is assessed visually and by scratching, the following classification is carried out: 0 = no change found; 1 = swelling ring, surface hard, only visible change; 2 = swelling ring, slight softening; 3 = significant softening (possibly little blistering); 4 = severe softening (possibly strong blistering), can be scratched to the surface; 5 = coating completely destroyed without external influence.

The viscosity measurements were carried out using a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) in accordance with DIN EN ISO 3219: 1994-08.

The pendulum damping was measured according to DIN EN ISO 1522: 2000-09 on a glass plate and was determined according to König.

The STP films were applied to glass plates with a squeegee. The film thickness was 30-35 pm for all films. Setalux DA 870 BA is a commercially available polyacrylate polyol, which was obtained from Allnex. It has an OH content of 4.2% by weight (based on the solid) and is supplied in butyl acetate (70%). The viscosity (23 ° C) is 7500 mPas.

The raw materials were either manufactured by Covestro AG itself or were obtained from Sigma-Aldrich and used without further purification. Phosphoric acid was used at 85% by weight (water) and 100%.

The catalyst X-Add KR 9006 contains a metal complex based on aluminum oxide, which was obtained in solution in n-butanol from Nano-X.

The Nacure 4167 catalyst is an amine-neutralized phosphate catalyst. The weak acid catalyst was obtained from King Industries.

The Nacure 4575 catalyst is an amine-neutralized phosphate catalyst. The acid catalyst was purchased from King Industries.

The Nacure 4000 catalyst is a catalyst based on alkyl phosphates (methyl) of various functions. The acid catalyst was purchased from King Industries. The catalyst K-Kat XK 678 is a catalyst based on alkyl phosphates with various functions. The acid catalyst was purchased from King Industries.

Synthesis of the sample compounds

Polymeric polyol Al)

70% polyacrylate polyol dissolved in butyl acetate, made from 6.3% ethyl acrylate, 0.7% acrylic acid, 17.6% isobornyl acrylate, 21.1% hydroxyethyl methacrylate, 7% methyl methacrylate, 14.3% styrene. OH content: 2.4-2.7%; Acid number: 7 + 1 mg; Viscosity (23 ° C): 1200 ± 200 mPas; Solids: 70.0% ± 2.0%.

example 1

934 g of HDI were placed in a glass reactor and 1.3 g of Borchi Kat 22 were added. 364 g of 3-mercaptopropyltrimethoxysilane were then added dropwise. The reaction solution was stirred until an NCO content of 24% by weight was reached. After addition of orthophosphoric acid (20% by weight in i-PrOH), the unreacted monomeric HDI was separated off at a temperature of 130 ° C. and a pressure of 0.1 mbar by means of two-stage thin-film distillation. A practically colorless, clear isocyanatosilane was obtained with the following characteristics: NCO = 11.2%; Solids content = 100% by weight; Viscosity = 515 mPas. Example 2

2220 g (10 mol) of isophorone diisocyanate (IPDI) were mixed with 196 g (1.0 mol) of mercaptopropyltrimethoxy silane at a temperature of 80 ° C under dry nitrogen and after addition of 0.06 g (25 ppm) of dibutyltin dilaurate (DBTL) 3 Stirred for hours until an NCO content of 33.0%, corresponding to a complete conversion, was reached. The unreacted monomeric IPDI was then separated off at a temperature of 150 ° C. and a pressure of 0.1 mbar in a thin-film evaporator. A practically colorless, clear isocyanatosilane was obtained with the following characteristics: NCO content = 9.7%; Solids content = 100%; Viscosity (23 ° C) = 5,400 mPas. Example 3

470.81 g of Example 1, 4.59 g of tetraethyl orthoformate (TEOF) and a drop of DBTL are mixed at 80 ° C. under dry nitrogen with 89.2 g of 2-ethyl-1,3-hexanediol. After 5 h, another drop of DBTL is added and the reaction is stirred until a residual NCO of <0.3% is reached. 114.76 g of butyl acetate (BuAc) are added to the crude product. A practically colorless silane with the following characteristics is obtained: residual NCO content = 0.17%; Viscosity (23 ° C) = 495 mPas; Solids = 80%.

Example 4

478.03 g of Example 1, 15.02 g of TEOF and 10 drops of DBTL are mixed at 80 ° C. under dry nitrogen with 764.91 g of polymeric polyol Al and 38.83 g of Stabaxol 1 and the reaction is stirred until a remainder -NCO of <0.3% is reached. The crude product is mixed with 203.21 BuAc. A practically colorless, clear silane is obtained with the following characteristics: residual NCO content = 0.26%; Viscosity (23 ° C) = 723 mPas; Solid = 70%.

Example 5

540.1 g of Example 2, 4.59 g of tetraethyl orthoformate (TEOF) and a drop of DBTL are mixed at 80 ° C. under dry nitrogen with 89.2 g of 2-ethyl-1,3-hexanediol. After 5 h, another drop of DBTL is added and the reaction is stirred until a residual NCO of <0.3% is reached. 127.0 g of butyl acetate (BuAc) are added to the crude product. A practically colorless silane is obtained with the following characteristics: residual NCO content = <0.3%; Viscosity (23 ° C) = 9000 mPas; Solids = 80%; Production of basecoat-coated aluminum sheets

Cleaning: The aluminum plates were cleaned with acetone. Filler: Use of Spies Hecker Permasolid HS Vario primer filler 5340. Hardener: Permasolid VHS hardener 3255. Dilution to 70-80% with Permacron. Spray painting. Drying 30 min, 60 ° C.

Basecoat: Spies Hecker Permahyd basecoat 280 super deep black. Dilution with demineralized water (95%). Baking conditions: 80 ° C, 10 min or approx. 30 min air drying.

In the experiments, a mixture of Example 3, Example 4 and Example 5 was used in a ratio of 7: 3: 1 based on the solids content for the topcoat. The molar amount of catalyst used agrees in the experiments, the different amounts (% by weight) result from the different catalyst molecular weights. Curing was carried out on the specified surface for 30 min at 60 ° C. The results are summarized in Table 1 below:

[l] l, 8-diazabicyclo [5.4.0] undec-7-ene, [2] trimethylguanidine, [3] benzyltrimethylammonium hydroxide, [4] dibutlytin dilaurate, [5] coating too soft.

The experiments show that the drying and crosslinking of the STPs on glass is fast, whereas a slow drying is observed on basecoat. For experiment No. 1 it was observed that a TI drying time with DBU on glass was reached within 20 min; on basecoat, this drying was outside the observation period, ie above 180 min. This observation was also confirmed by the development of pendulum hardness on glass and basecoat. The final pendulum hardness (211 s) of the silane-terminated prepolymer was reached on glass after one day. Only a pendulum hardness of 28s was achieved on basecoat even after storage for seven days. So there is a strong dependency of the achievable values as Function of the substrate, whereby it is more difficult to obtain acceptable values on basecoats. In the crosslinking experiments of the STP clearcoat coatings on basecoats, it was also found that basic catalysts lead to no or only insufficient crosslinking of the silane-terminated prepolymers. This is demonstrated using the tests shown in Table 1, the tests shown in the test series (No. 1-3) being bases. The experiments (No. 5-7) show that amine-neutralized catalysts and an aluminum oxide-based metal complex known from the prior art lead to even worse physical properties of the multilayer structures produced.

The influence of the substrate is not only reflected in the drying behavior of the coating material, but also in the resistance to solvents. A very good solvent resistance (1 0 0 4) was observed on glass as the coating substrate by means of DBU catalysis, whereas a completely inconsistent film was obtained on the basecoat (5 5 5 5). The described coating properties such as drying, pendulum hardness and resistance to solvents allow very good statements to be made about the networking of the system. If the experiment is repeated with other catalyst systems, the results can be found in Table 2 below:

* RT drying

Surprisingly, when using protonic acids as catalysts, it was found that the drying times between glass substrates and basecoat did not differ significantly. It was also found that in many films a final pendulum hardness between 70 s and 80 s pendulum seconds was reached after just one day; Basically, lower pendulum seconds on basecoat are observed compared to glass. In addition, the drying time T of phosphoric acid on glass and basecoat is in the same time frame. This also applies to the formation of the maximum pendulum hardness, both for tempering on glass as well Basecoat is complete after one day, as the values for glass (213 s / 219 s) after ld and 7d and on basecoat (70 s / 71 s) after ld and 7d show. The robustness of the

Protonic acid catalysts are also reflected in the solvent resistance of the STP films, which is independent of the substrate. Resistance to 0 0 4 4 for example no. 13 and 0 0 4 5 to basecoat were found on glass. This is not a significant difference. The results shown here illustrate that with protonic acid catalysts, STPs are independent of the substrate - glass vs. Basecoat - can be cured.

In a further test, the results were verified against a comparison paint (2K PU paint system). It was coated on a black basecoat. The clearcoat coating was cured on the basecoat, equivalent to the other examples, at 60 ° C. and 30 minutes.

Table 3 shows the formulations of the individual coatings:

The STP coating systems specified above were compared with the 2K PU coating system in terms of their drying kinetics and solvent resistance. The results are as follows:

From the drying times and from the solvent resistance, it was found that the properties of the STP topcoats catalyzed according to the invention correspond to those of a 2-component PU coating system. For example, for example no. 14 it results that the drying times are 20 26 34 minutes. For the 2K PU reference, however, drying times T of 20 20 25 minutes are obtained on the basecoat. This finding proves that the drying times for the two coating systems do not differ significantly. The solvent resistance for the 2-component PU reference is - 1 2 4 5 - after 7 days and for the inventive structure no. 14 - 2 2 4 4. This shows that the example according to the invention is analogous to a 2-component in terms of drying time and solvent resistance PU coating material is.

Weathering results

In order to demonstrate the durability and adhesion of the coating materials, short weathering tests were carried out using the SAE J 2527 method. For this purpose, the following formulation was applied to a black basecoat using a spray gun and cured at 60 ° C. for 30 minutes. The multilayer structure was then weathered over a period of 1500 h. The multilayer structure was carried out on filled aluminum panels on black basecoat (see multilayer structure "filler" and "basecoat"). The 2K PU car repair clearcoat was obtained from Spiess Hecker (Permasolid® HS Klarlack 8055, Permasolid® VHS Hardener 3225). Formulation top coat

Example 3, Example 4 and Example 5 were mixed together in a ratio of 7: 3: 1. 45 g of this mixture were mixed with 0.69 g dibutyl phosphate, 0.18 g BYK 315 N, 2.12 g Tinuvin 5100 and 23 g methoxypropyl acetate (MPA). This formulation was then applied to a basecoat using a spray gun and dried for 30 min, 60 ° C. to form a hardened multilayer structure.

The cross-cut test was carried out according to DIN EN ISO 2409: 2013-06.

The glossy haze and the gloss measurements showed that high-gloss laminates are available. The weathering tests also showed that the gloss is very weather-resistant and the values obtained change only insignificantly. The cross-cut test also shows very clearly that there is an excellent overall adhesion of the layer composite and also a good adhesion of the composite to the substrate.

Claims

1. A method for producing an at least two-layer lacquer structure from a lower basecoat and an upper topcoat layer arranged above it on a substrate, characterized in that the method comprises the steps: a) applying a basecoat layer comprising polymers selected from the group consisting of polyacrylates , Polyurethanes, polyether polyols, polycarbonate polyols, polyester polyols, melamine resins, alkyd resins or mixtures thereof on a substrate; b) at least partial curing of the basecoat film; c) applying a topcoat to the basecoat layer applied in step b), the topcoat being the structuring component containing prepolymers containing silane groups with a content of greater than or equal to 20% by weight and less than or equal to 100% by weight based on the cured topcoat layer and comprises a catalyst with a content of greater than or equal to 0.01% by weight and less than or equal to 5% by weight, based on the cured topcoat layer, and the catalyst is selected from the group consisting of protonic acids or mixtures thereof; d) reacting the layer applied in step c) to obtain the top coat layer.

2. The method according to claim 1, wherein the silane group-containing prepolymers in step c) are silane-terminated prepolymers, preferably silane-terminated polyurethanes.

3. The method according to any one of the preceding claims, wherein the catalyst is a polybasic protonic acid.

4. The method according to any one of the preceding claims, wherein the catalyst is a polybasic protonic acid with a pKa value of greater than or equal to -14.0 and less than or equal to 4.0.

5. The method according to any one of the preceding claims, wherein the catalyst is a substituted or unsubstituted phosphoric acid.

6. The method according to any one of the preceding claims, wherein the catalyst is selected from the group consisting of phosphoric acid and CI -CI 5 alkyl, aryl, cycloalkyl substituted phosphoric acids or mixtures thereof.

7. The method according to any one of the preceding claims, wherein the catalyst in step c) in a concentration of greater than or equal to 0.03 wt .-% and less than or equal to 3rd

% By weight is used.

8. The method according to claim 2, wherein the silane group-containing prepolymers in step c) are silane-terminated polyurethanes which have a residual NCO content, determined according to DIN EN ISO 11909: 2007-05, of greater than or equal to 0.0005% and less or equal 1%.

9. The method according to claim 2 or 8, wherein the silane group-containing prepolymers in step c) are silane-terminated polyurethanes which have a viscosity determined according to DIN EN ISO 3219: 1994-08 of greater than or equal to 50 mPas and less than or equal to 5000 mPas exhibit.

10. Layered composite of a lower basecoat and a topcoat layer arranged above, characterized in that the lower basecoat layer contains polymers selected from the group consisting of polyacrylates, polyurethanes, polyether polyols, polycarbonate polyols, polyester polyols, melamine resins, alkyd resins or mixtures thereof and the upper topcoat layer contains crosslinked polymers containing silane groups and protonic acids or mixtures thereof, the acids being selected from the group consisting of phosphoric acid, C 1 -C 5 alkyl, aryl, cycloalkyl-substituted phosphoric acids or mixtures thereof.

11. Laminate according to claim 10, wherein the upper topcoat layer at a layer thickness of 50 pm on a white basecoat has a Delta Lab value in relation to the white basecoat of AL greater than or equal to 0.2 and less than or equal to 20, greater than or equal to Aa equal to -0.01 and less than or equal to -20, and Ab greater than or equal to -0.01 and less than or equal to -13, which was determined in accordance with DIN EN ISO 1166-4: 2012-06.

12. Laminate according to one of claims 10 - 11, wherein the upper topcoat layer with a layer thickness of 50 pm a total transmission according to ISO 14782: 1999-08 / ASTM D1003: 2013-ll of greater than or equal to 85% and less than or equal to 99.5 % and a Has turbidity greater than or equal to 0.5 and less than or equal to 15.

13. Laminate according to one of claims 10 - 11, wherein the upper top coat layer has a pendulum hardness determined according to DIN EN ISO 1522: 2000-09 of greater than or equal to 50 s and less than or equal to 180 s.

14. Use of a layer composite according to one of claims 10-13 for coating a substrate.

15. Vehicle or vehicle body part with a layer composite according to one of claims 10-13.