EP1802719A1

EP1802719A1 - Highly scratch-resistant and highly elastic coating agents based on alkoxysilane-functional components

Info

Publication number: EP1802719A1
Application number: EP05784747A
Authority: EP
Inventors: Andreas Poppe; Günter Klein; Karin Wermelt; Martina MÖLLERS; Andre Brosseit
Original assignee: BASF Coatings GmbH
Current assignee: BASF Coatings GmbH
Priority date: 2004-10-19
Filing date: 2005-09-03
Publication date: 2007-07-04
Also published as: DE102004050746A1; JP2008517111A; WO2006042584A8; US20080047469A1; JP4940142B2; KR20070091276A; WO2006042584A1; US7772320B2; CN101040019A; CN101040019B

Abstract

The invention relates to thermally curing coating agents which comprise (A) at least 50 % by weight, based on the content in nonvolatile substances in the coating agent, of (A1) 0 to 50 % by weight, based on the total of components (A1) and (A2), of a polymethacrylate copolymer which comprises more than 50 % by weight, based on the total of comonomers in copolymer (A1), of a radically polymerizable, ethylenically unsaturated compounds (a1) having at least one reactive group of formula (I) -X-SiR'x(OR')3-x (I), and (A2) 50 to 100 % by weight, based on the total of components (A1) and (A2), of an adduct from polyisocyanate and alkoxysilane, whereby (A2) contains at least one reactive group of formula (II): -NR-C(O)-N-(X-SiR'x(OR')3-x)n(X'-SiR'y(OR')3-y)m (II), (B) a catalyst for cross-linking the -Si(OR')3-x units, and (C) an aprotic solvent or a mixture of aprotic solvents.

Description

High scratch resistant and highly elastic coating agent based on alkoxysilane-functional components

The present invention relates to thermally curable coating compositions based on aprotic solvents and based on alkoxysilane-functional components having high scratch resistance and high rubber elasticity, which are particularly suitable for plastic coating.

Coating compositions comprising binders based on poly (meth) acrylates which have lateral and / or terminal alkoxysilane groups are known, for example, from the patents or patent applications US Pat. No. 4,043,953, US Pat. No. 4,499,150, US Pat 4,499,151, EP-A-549,643 and WO-A-92/20643. The poly (meth) acrylates described there may contain up to 70% by weight of comonomers with alkoxy groups, based on all the comonomers used. The coating compositions are cured by catalysis of Lewis acids and, if appropriate, in the presence of small amounts of water to form Si-O-Si networks. The coating compositions are used inter alia as clearcoats. Although such clearcoats already have a high scratch resistance and a comparatively good weather resistance, they have deficits in the rubber elasticity which make it difficult to use as highly stressable clearcoats, in particular for plastics.

EP-A-0 267 698 describes solventborne coating compositions which comprise crosslinkable adducts with alkoxysilane groups as binder components (1), obtainable by successive reaction of polyisocyanates with hydroxyalkyl (meth) acrylates (Michael reaction) and then with aminoalkylalkoxysilanes, and ( 2) poly (meth) acrylates containing lateral and / or terminal alkoxysilane groups. The readily accessible amine groups in the adducts formed in the Michael reaction lead to a reduction in the water resistance of the cured coatings. Furthermore, in the curing process, these amine groups can form Si-N-C network points by reaction with the -Si (O-alkyl) 3 groups, which are hydrolysis-labile and lead to a reduced chemical resistance of the resulting coating. Such coating compositions also have deficits in rubber elasticity.

US Pat. No. 4,598,131 describes solvent-borne coating compositions comprising crosslinkable adducts with alkoxysilane groups, obtainable by successive reaction of tetraalkyl orthosilicate with aminoalcohols and then with polyisocyanates. Due to the nature of the synthesis, such adducts have undesirable Si-O-C or Si-N-C network points, which are hydrolysis-stable and lead to a reduced chemical resistance of the resultant coating. Furthermore, such coating agents also have deficits in rubber elasticity.

DE-A-102 37 270 comprises coating compositions comprising crosslinkable adducts of isocyanatomethylalkoxysilanes and polyols. The isocyanatomethylalkoxysilanes used in the synthesis are highly toxic and therefore only of limited use in customary production processes.

EP-A-0 571 073 describes solvent-borne coating compositions which comprise crosslinkable adducts of polyisocyanates having more than one tertiary isocyanate group and aminoalkylalkoxysilanes and (2) poly (meth) acrylates which have lateral and / or terminal alkoxysilane groups as binder components (1). contain. Although the resulting coatings have a comparatively high scratch resistance, the rubber elasticity of the coating is not yet sufficient, especially in the case of highly stressed transparent applications on plastic substrates. Task and solution

The object of the present invention was to provide coating compositions, preferably for high-load-bearing clearcoats, in particular for plastic substrates, which in particular do not have the elasticity deficits, in particular in terms of rubber elasticity, of the coatings of the prior art. The coatings should, in particular, be highly rubber-elastic and scratch-resistant and have a high transparency after scratching. In particular, the coatings according to the invention should fulfill the requirements of the Taber test. Furthermore, the coatings and coatings should be highly transparent and weather-stable. For the weathering stability, it was necessary to ensure good incorporability of UV absorbers in the coating compositions of the invention. In addition, the novel coating compositions should be easy to produce and very easy to reproducibly produce, pose no ecological problems and have good storage stability.

Accordingly, thermosetting aprotic solvent-based coating compositions were found containing

(A) at least 50 wt .-%, based on the content of non-volatile

Substances in the coating agent, a mixture of

(A1) 0 to 50% by weight, based on the totality of the components (A1) and (A2), of a polymethacrylate copolymer containing more than 50% by weight, based on the total of the comonomers in the copolymer ( A1), free-radically polymerizable, ethylenically unsaturated compounds (a1) having at least one reactive group of the formula I -X-SiR "x (0R ') 3-x (I)

R '= hydrogen, alkyl or cycloalkyl, wherein the carbon chain by non-adjacent oxygen, sulfur or NRa

Groups may be interrupted with Ra = alkyl, cycloalkyl, aryl or aralkyl,

X = linear and / or branched alkylene or cycloalkylene radical having 2 to 20 carbon atoms, R "= alkyl, cycloalkyl, aryl or aralkyl, where the Kohlenstoffket¬ te may be interrupted by non-adjacent oxygen, sulfur or NRa groups,

x = 0 to 2,

and

(A2) 50 to 100 wt .-%, based on the totality of components (A1) and (A2), of an adduct (A2) of at least one polyisocyanate and at least one alkoxysilane, wherein (A2) at least one reactive group of Formula Il contains:

-NR-C (O) -N- (X-SiR "x (OR ^I) 3-x) n (X ^I -SiR" y (OR ¹⁾ 3-y) m (II)

where X and R "represent the structural units described in formula I and with

R = hydrogen, alkyl, cycloalkyl, aryl or aralkyl, wherein the carbon chain may be interrupted by non-adjacent oxygen, sulfur or NRa groups, X '= linear and / or branched alkylene or cycloalkylene radical having 2 to 20 carbon atoms, Ra = Alkyl, cycloalkyl, aryl or aralkyl, x = y = 0 to 2, n = 0 to 2, m = 0 to 2, m + n = 2,

(B) a catalyst for cross-linking the -Si (OR ') 3-x units, and

(C) an aprotic solvent or a mixture of aprotic solvents.

With regard to the prior art, it was surprising and unforeseeable for the person skilled in the art that the objects on which the present invention was based could be achieved with the aid of the coating material according to the invention.

The component (A) according to the invention can be prepared particularly simply and prepares no significant toxicological and ecological problems during the paint application.

The coating compositions according to the invention can be prepared very readily reproducibly and, when used in the liquid state, could be adjusted to solids contents> 40% by weight, preferably> 45% by weight, in particular> 50% by weight, without As a result, their very good transportability, storage stability and processability, in particular their applicability, are adversely affected. Furthermore, the coating compositions according to the invention have good incorporability for, in particular hydrophobic, UV absorbers.

The novel coating compositions provide new coatings and coatings, especially clearcoats, which are highly scratch-resistant and highly elastic. The transparency, in particular the haze, of the coatings, especially after exposure, is excellent. Which he- Coatings and coatings according to the invention, in particular the clearcoats, can be used in particular for the coating of plastics. They are characterized by a particularly high scratch resistance in the Taber test.

Description of the invention

Component (A) of the coating agent

Component (A) of the coating composition of the invention contains at least 50% by weight, based on the nonvolatile substances of the coating composition, of components (A1) of from 0 to 50% by weight, preferably from 0 to 45% by weight, particularly preferably 0 to 40% by weight, based on the totality of components (A1) and (A2), of a polyacrylate copolymer containing more than 50% by weight, based on the total of the comonomers in the copolymer (A1), free-radically polymerizable, ethylenically unsaturated compounds (a1), and (A2) 50 to 100 wt .-%, preferably 55 to 100 wt .-%, particularly preferably 60 to 100 wt .-% based on the Compound of components (A1) and (A2), an adduct of polyisocyanate and alkoxysilane.

The component (A1) of the coating composition is a polymethacrylate copolymer with more than 50% by weight, preferably more than 55% by weight, particularly preferably more than 60% by weight, based on the total of the comonomers in the copolymer (A1 ), to radically polymerisierba¬ ren, ethylenically unsaturated compounds (a1) having at least one reactive group of the formula I.

-X-SiR "x (OR ') 3-x (I)

R '= hydrogen, alkyl or cycloalkyl, wherein the carbon chain by non-adjacent oxygen, sulfur or NRa groups, with Ra = Alkyl, cycloalkyl, aryl or aralkyl, where R 'is preferably alkyl having 1 to 6 carbon atoms, more preferably methyl and / or ethyl,

X = linear and / or branched alkylene or cycloalkylene radical having 2 to 20 carbon atoms, where X is preferably alkylene having 2 to 6 carbon atoms, particularly preferably alkylene having 2 to 4 carbon atoms,

R "= alkyl, cycloalkyl, aryl or aralkyl, wherein the carbon chain may be interrupted by non-adjacent oxygen, sulfur or NRa groups, wherein R" is preferably alkyl having 1 to 6 carbon atoms, more preferably methyl and / or ethyl and x = 0 to 2, preferably x = 0.

Particularly preferred compounds (A1) are described, for example, in EP-B1-0 549 643 (page 3, Z.47 to page 4, line 34). Very particularly preferred compounds (a1) are acrylates and / or methacrylates having reactive groups (I), for example gamma-acryloxypropyltrimethoxysilane, acryloxymethyltrimethoxysilane, methacryloxymethyltrimethoxysilane or, in particular, gamma-methacryloxypropyltrimethoxysilane.

The proportions of <50% by weight, preferably <45% by weight, particularly preferably <40% by weight, based on the total of the comonomers, of free-radically polymerizable, ethylenically unsaturated comonomer building blocks present in the copolymer (A1) ( a2) are free-radically polymerizable, ethylenically unsaturated compounds, preferably acrylates and / or methacrylates, optionally further alkyl, cycloalkyl, aryl and (f) bearing alkyl groups bearing reactive functional groups (f) which are different from the reactive groups of the formulas I and II. or aralkyl esters of acrylic and / or methacrylic acid. The reactive functional groups (f) may be radiation-crosslinking and / or thermally crosslinking groups known per se, for example vinyl, (meth) acryloyl or allyl groups as radiation-crosslinking groups, and also mixed crosslinking groups, such as epoxy, isocyanate carbamate and / or substituted amino groups. The reactive functional groups (f) are preferably selected in such a way that hydrolysis-labile Si-NC and / or Si-OC network points are not or only to a very limited extent formed during the curing of the coating compositions. Particularly preferred compounds (a2) are alkyl and / or cycloalkyl esters of (meth) acrylic acid having 1 to 10 carbon atoms.

The compound (A2) has at least one reactive group of the formula II:

-NR-C (O) -N- (X-SiR "x (OR ¹⁾ 3-x) n (X'-SiR" y (OR ¹⁾ 3-y) m (II)

With

R = hydrogen, alkyl, cycloalkyl, aryl or aralkyl, where the carbon chain can be interrupted by nonadjacent oxygen, sulfur or NRa groups, where R a = alkyl, cycloalkyl, aryl or aralkyl,

R '= hydrogen, alkyl, or cycloalkyl, wherein the carbon chain may be interrupted by non-adjacent oxygen, sulfur or NRa groups, wherein R' is preferably alkyl having 1 to 6 carbon atoms, more preferably methyl and / or ethyl X ₁ X '= linear and / or branched alkylene or cycloalkylene radical having 2 to 20 carbon atoms, where X ₁ X' are preferably alkylene having 2 to 6 carbon atoms, particularly preferably alkylene having 2 to 4 carbon atoms, R "= Alkyl, cycloalkyl, aryl or aralkyl, where the carbon chain may be interrupted by nonadjacent oxygen, sulfur or NRa groups, where R "is preferably alkyl having 1 to 6 carbon atoms, particularly preferably methyl and / or ethyl, n = 0 to 2, m = 0 to 2, m + n = 2, and x, y = 0 to 2, preferably x = 0.

The component (A2) is preferably prepared with the reactive groups of the formula II by reacting at least one di- and / or polyisocyanate (PI) with at least one aminodisilane of the formula III:

HN- (X-SiR "x (OR ^I ) 3-x) n (X ¹ -SiR" y (OR ¹ ) 3-y) m (III),

wherein the substituents and indices are as defined above.

Particularly preferred amindiosilanes (III) are bis (2-ethyltrimethoxysilyl) amine, bis (3-propyltrimethoxysilyl) amine, bis (4-butyltrimethoxysilyl) amine, bis (2-ethyltriethoxysilyl) amine, bis (3-propyltrimethoxysilyl) amine and / or bis (4-butyltriethoxysilyl) amine. Very particular preference is given to bis (3-propyltrimethoxysilyl) amine. Such aminodisilanes are available, for example, under the brand name SIL-Quest® from OSI.

Preferred di- and / or polyisocyanates PI for the preparation of component (A2) are known per se known substituted or unsubstituted aromati cal, aliphatic, cycloaliphatic and / or heterocyclic polyisocyanates. Examples of preferred polyisocyanates are: 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, p-phenylene diisocyanate, biphenyl diisocyanates, 3,3'-dimethyl-4 , 4'-diphenylene diisocyanate, tetra-methylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, 2,2,4-trimethylhexane-1,6-diisocyanate, isophorone diisocyanate, ethylene diisocyanate, 1,12-dodecane diisocyanate, Cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, methylcyclohexyldiiso- cyanates, hexahydrotoluene-2,4-diisocyanate, hexahydrotoluene-2,6-diisocyanate, hexahydrophenylene-1,3-diisocyanate, hexahydrophenylene-1,4-diisocyanate, perhydrodiphenylmethane-2,4'-diisocyanate, 4,4'-methylenedicyclohexyldiisocyanate ( eg Desmodur® W from Bayer AG), tetramethylxylyl diisocyanates (eg TMXDI® from American Cyanamid) and mixtures of the abovementioned polyisocyanates. Further preferred polyisocyanates are the biuret dimers and the isocyanurate trimers of the aforementioned diisocyanates. Particularly preferred polyisocyanates PI are hexamethylene-1,6-diisocyanate, isophorone diisocyanate and 4,4'-diisocyanate.

Methylenedicyclohexyl diisocyanate, their biuret dimers and / or isocyanurate trimers.

In a further embodiment of the invention, the polyisocyanates PI are polyisocyanate prepolymers having urethane structural units, which are obtained by reacting polyols with a stoichiometric excess of the aforementioned polyisocyanates. Such polyisocyanate prepolymers are described, for example, in US Pat. No. 4,598,131. Very particularly preferred components (A2) are: reaction products of hexamethylene-1,6-diisocyanate and isophorone diisocyanate, and / or their isocyanurate trimers with bis (3-propyltrimethoxysilyl) amine.

The reaction of the polyisocyanates is carried out with the aminosilanes vor¬ preferably in an inert gas atmosphere at temperatures of up to 100 ⁰ C, preferably of maximum 60 ⁰ C.

According to the invention, the resulting component (2) has at least one structural unit of the abovementioned formula (II); according to the preferred preparation method according to the invention, preferably at least 90 mol% of the isocyanate groups of the polyisocyanate PI are the aminodisilanes (III), more preferably at least 95 mol%, converted into structural units (II). The proportion of components (A1) and (A2) in the coating composition according to the invention is at least 50 wt .-%, based on the content of nonvolatile substances in the coating composition, preferably at least 60 wt .-%, particularly preferably at least 70 wt .-%.

The other components of the coating agent

As catalysts (B) for the crosslinking of -Si (OR ') 3-x (y) units known compounds can be used. Examples are Lewis acids (electron deficiency compounds), such as, for example, tin naphthenate, tin benzoate, tin octoate, tin bromate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin oxide, lead octoate. As catalysts, metal complexes with chelating ligands are preferably used. The chelating ligand-forming compounds are organic compounds having at least two functional groups capable of coordinating with metal atoms or ions. These functional groups are usually electron donors, which donate electrons to metal atoms or ions as electron acceptors. In principle, all organic compounds of the type mentioned are suitable as long as they do not adversely affect or even completely prevent the crosslinking of the curable compositions according to the invention to give cured compositions according to the invention. For example, the aluminum and zirconium chelate complexes, as described, for example, in US Pat. No. 4,772,672 A, column 8, line 1, to column 9, line 49, can be used as catalyst. Particularly preferred are aluminum, zirconium, titanium and / or boron chelates, such as, for example, aluminum ethyl acetoacetate and / or zirconium ethyl acetoacetate. Most preferred are aluminum chelates.

Also particularly preferred are aluminum, zirconium, titanium and / or boron alcoholates and / or esters. Furthermore, particularly preferred as component (B) are nanoparticles. Such nanoparticles are preferably incorporated into the network points at least partially during the crosslinking of the -Si (OR ') 3-x (y) units. Preferably, the nanoparticles are selected from the group consisting of metals and compounds of metals, preferably compounds of metals.

Preferably, the metals from the third and fourth Haupt¬ group, the third to sixth and the first and second subgroup of the Periodic Table of the Elements and the lanthanides, and preferably from the group consisting of boron, aluminum, gallium, silicon Si , Germanium, tin, zinc, titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten and cerium. In particular, aluminum, silicon, titanium and / or zirconium are used. The compounds of the metals are preferably oxides, hydrated oxides, sulfates, hydroxides or phosphates, in particular oxides, oxide hydrates and hydroxides. Very particular preference is given to boehmite nanoparticles. The nanoparticles preferably have a primary particle size of <50, preferably 5 to 50, in particular 5 to 30 nm.

The catalyst component (B) is preferably used in proportions of from 0.01 to 30% by weight, more preferably in proportions of from 0.1 to 20% by weight, based on the nonvolatile constituents of the coating composition according to the invention.

Suitable further components (C) are solvents which are chemically inert in the coating composition compared to the components (A) and (B) and which also do not react with (A) and (B) during the curing of the coating agent. Examples of such solvents are aliphatic and / or aromatic hydrocarbons, such as toluene, xylene, solvent naphtha, Solvesso 100 or Hydrosol® (ARAL), ketones, such as acetone, methyl ethyl ketone or methyl amyl ketone, esters, such as ethyl acetate, Butyl acetate, pentyl acetate or ethyl ethoxypropionate, ethers or mixtures of the abovementioned solvents. The solvents or solvent mixtures preferably have a water content of not more than 1% by weight, more preferably not more than 0.5% by weight, based on the solvent. In a preferred embodiment of the invention, a mixture of components (A) and (C) is first prepared, which is mixed in a further step with the other components of the coating composition according to the invention.

In addition, the coating composition according to the invention can contain at least one customary and known coating additive in effective amounts, i. in amounts preferably up to 30 wt .-%, particularly preferably up to 25 wt .-% and in particular up to 20 wt .-%, each based on the nonvolatile constituents of the coating composition.

Examples of suitable paint additives are: in particular UV absorbers; in particular light stabilizers such as HALS compounds, benzotriazoles or oxalanilides;

Radical scavengers;

slip additives;

polymerization inhibitors;

defoamers; Reactive diluents, as are well known in the art, which preferably do not react with the -Si (OR ') 3 groups of component (A) to form -Si-O-C- and / or

-Si-N-C network points respond.

Wetting agents such as siloxanes, fluorine-containing compounds, carboxylic acid half esters, phosphoric esters, polyacrylic acids and their copolymers or polyurethanes;

Adhesion promoters such as tricyclodecanedimethanol; Leveling agents; film-forming aids such as cellulose derivatives; fillers other than component (B), such as, for example, nanoparticles based on silicon dioxide, aluminum oxide or zirconium oxide; in addition is still on the Römpp

Lexicon "Paints and Printing Inks" Georg Thieme Verlag, Stuttgart, 1998, pages 250 to 252, referenced; Rheology control additives such as those known from the patents WO 94/22968, EP-A-0 276 501, EP-A-0 249 201 or WO 97/12945; crosslinked polymeric microparticles such as disclosed in EP-A-0 008 127; inorganic sheet silicates such as aluminum-magnesium silicates, sodium magnesium and sodium magnesium fluorine lithium phyllosilicates of the montmorillonite type; Silicas such as aerosils; or synthetic polymers having ionic and / or associative groups such as polyvinyl alcohol, poly (meth) acrylamide, poly (meth) acrylic acid, polyvinylpyrrolidone, styrene-maleic anhydride or ethylene-maleic anhydride copolymers and their derivatives or hydrophobically modified ethoxylated urethanes or polyacrylates; and / or flame retardants.

In a further embodiment of the invention, the coating composition according to the invention may contain further pigments and / or fillers and serve for the production of pigmented topcoats. The pigments and / or fillers used for this purpose are known to the person skilled in the art.

The application of the coating compositions according to the invention can be carried out by all customary application methods, such as, for example, spraying, knife coating, spreading, casting, dipping, impregnating, trickling or rolling. In this case, the substrate to be coated can rest as such, with the application cation device or -anläge is moved. However, the substrate to be coated, in particular a coil, can also be moved, with the application system resting relative to the substrate or being moved in a suitable manner. Preferably, spray application methods are used, such as compressed air spraying, airless spraying, high rotation, electrostatic spray application (ESTA), optionally combined with hot spray application, such as, for example, hot air hot spraying. The curing of the applied coating compositions according to the invention can take place after a certain period of rest. The rest period is spielsweise to the course and degassing of the paint layers or for the evaporation of volatile components such as solvents. The Ruhe¬ time can be supported and / or shortened by the application of elevated temperatures and / or by a reduced air humidity, provided that no damage or changes in the paint layers occur, such as premature complete networking.

The thermal curing of the coating compositions has no methodical particularities, but takes place by the usual and well-known methods such as heating in a convection oven or irradiation with IR lamps. Here, the thermal curing can also be done gradually. Another preferred curing method is near infrared (NIR) curing. Advantageously, the thermal curing is carried out at a temperature of 50 to 160 ⁰ C, more preferably 60 to 150 ⁰ C and in particular 80 to 14O ⁰ C for a time of 1 min to 5 h, particularly preferably 2 min to 2 h and especially 3 minutes to 90 minutes.

The coating compositions according to the invention provide new cured coatings, in particular coatings, especially clearcoats, moldings, especially optical moldings, and self-supporting films which are highly scratch-resistant and, in particular, resistant to chemicals and weathering. INS In particular, the coatings and coatings according to the invention, especially the clearcoats, can also be produced in layer thicknesses> 40 μm without stress cracks occurring.

The coating compositions according to the invention are outstandingly suitable as decorative, protective and / or effective, highly scratch-resistant and highly elastic coatings and coatings of bodies of vehicles (in particular motor vehicles, such as motorcycles, buses, trucks or cars) or parts thereof; of buildings in the interior and exterior; of furniture, windows and doors; from

Plastic moldings, in particular CDs and windows; of industrial small parts, of coils, containers and packaging; of white goods; of films; of optical, electrotechnical and mechanical components as well as of hollow glass articles and everyday objects.

In particular, the coating compositions and coatings according to the invention, in particular the clearcoats, are used for the coating of preferably transparent plastics. They are characterized by a particularly high chemical and weather resistance, high transparency and a very good scratch resistance, which is proven by the relevant Taber test.

Examples

Preparation Example 1 - Preparation of a suitable catalyst (component (B))

In order to ensure sufficient curing of the clearcoat, a suitable catalyst is first prepared. For this purpose, 20.01 parts by weight of aluminum sec-butylate in a round bottom flask are slowly added at room temperature to 13.01 parts by weight of ethyl acetoacetate, the mixture being stirred and cooled. Subsequently, the reaction mixture is stirred for a further 1 h at room temperature.

Preparation Example 2 - Preparation of the Polyacrylate (A1a)

In a three-necked flask made of glass, equipped with a reflux condenser and a thermometer, 39.42 parts by weight of solvent naphtha are introduced and heated to 145 ° C. under a nitrogen atmosphere. At constant temperature, a mixture of 14.04 parts by weight of n-butyl methacrylate and 73.54 parts by weight of 3-methacryloxypropyltrimethylsiloxane within 2 hours and the initiator solution consisting of 10.28 parts by weight of tert-butyl peroxy-2-ethylhexanoate in 12,72 are simultaneously Parts by weight of solvent naphtha, dosed uniformly within 5 hours. After the feed of the initiator solution has ended, the temperature is kept at 145 ^° C. for 1.5 hours. Then it is cooled to room temperature.

The complete reaction was investigated by GC and the Molekularge¬ weight by GPC. This resulted in a total residual monomer content of 0.2% by weight (0.1% by weight of n-butyl methacrylate, 0.1% by weight of MEMO) and a mass-average molecular weight M w of 17,553 dalton and a number-average molecular weight of 2,175 Dalton.

In further preparation examples (A1 b) to (A1f), the monomer building block is n-butyl methacrylate by ethyl acrylate, n-butyl acrylate, methyl methacrylate and cyclohexyl methacrylate replaced, the preparation being carried out vorste¬ described.

Preparation Example 3.1 - Preparation of a Silanized Diisocvanate (IPDI) (Component (A2a))

20.72 parts by weight of Desmodur I (IPDI, Bayer) and 15.61 parts by weight of Hydrosol A 170 (Aral) are initially charged in a three-necked flask made of glass, equipped with a reflux condenser, a thermometer and a feed, while stirring and with Nitrogen is obscured. At 5 ° C, the feed is composed of 63.66 parts by weight of bis (trimethoxysilylpropyl) amine (available commercially as Silquest A1170 Fa. OSI) was then added over 1 dosed for 5 hours so that the temperature generated by the exothermic 1O ⁰ C is not exceeded.

The thus obtained mixture was stirred for 12 hours at room temperature and then at 6O ⁰ C until NCO value by means of a titrimetric determination of no free NCO groups were no longer detectable.

Preparation Example 3.2 Preparation of a Silanized Diisocvanate (HDI) (Component (A2b))

In a three-necked flask made of glass, equipped with a reflux condenser, a thermometer and a feed, 17.8 parts by weight of Desmodur H (HDI, ® Bayer) and 10.0 parts by weight of Hydrosol A 170 (® Aral) are introduced, stirring and with Nitrogen is obscured. At 0 ⁰ C, the feed is composed of 72.2 parts by weight of bis (trimethoxysilylpropyl) amine (available commercially as Silquest A1170 Fa. OSI) was then added over 1 dosed for 5 hours so that the temperature generated by the exothermic 1O ⁰ C does not exceed. The mixture thus obtained was stirred for a further 12 hours at room temperature and then at 60 ^° C. until no more free NCO groups could be detected by means of a titrimetric NCO value determination.

Comparative Example: Preparation of a silanized diisocyanate (HDI) with monofunctional silane amine:

In a three-necked flask made of glass, equipped with a reflux condenser, a thermometer and a feed, 17.8 parts by weight

Desmodur H (HDI, ® Bayer) and 10.0 parts by weight of Hydrosol A 170 (

Aral), stirring and sparging with nitrogen.

At ⁰ ° C., the feed consisting of 48.05 parts by weight (N-

Phenylaminomethyl) -trimethoxysilane (commercially available as Geniosil XL973 from Wacker)) and then added dropwise over 1.5 h in such a way that the temperature is due to the resulting exotherm

10 ⁰ C does not exceed.

The mixture thus obtained was allowed to stand for a further 12 hours

Room temperature and then stirred at 60 ⁰ C until no more free NCO groups were detectable by a titrimetric NCO value determination.

Formulation of scratch-resistant and chemical-resistant coating materials

For the formulation of highly scratch-resistant and chemical-resistant coating compositions, the diisocyanate adducts (A2a) and (A2b) described in Preparation Examples 3.1 and 3.2 were in a weight ratio with the alkoxysilane-functional polyacrylates (A1a) to (A1f) described under Preparation Example 2 (A1): (A2) = 25: 75 mixed, or used as pure components and mixed with the catalyst described in Preparation Example 1 (B). The resulting coating tung medium was applied and at 130 ⁰ C for 30 minutes einge¬ burned. The corresponding formulations (parts by weight) are based on the composition of the coating composition) and the results are summarized in Table 1.

Table 1- Preparation of Chemical Resistant. highly scratch-resistant coatings 1a to 1h with the coating compositions according to the invention (numerals in parts by weight) and the comparative example V

Table 2- Properties of the Coatings Produced with the Inventive Coating Materials

The scratch resistance of the surfaces of the resulting coatings 1a to 1 h was examined by means of the Taber test. The same procedure was followed with the diisocyanate adduct described in Comparative Example (Comparative Example 1) (Coating V). The Taber test was carried out after the wear test DIN 52347 (1000 cycles, CS10F, 500g) and then the haze of the damaged area was measured according to DIN 5036. After the load, the test surfaces were cleaned with a soft cloth from the steel wool residues. The test areas were visually evaluated under artificial light and graded as follows:

Note Damage picture

1 not available

2 low 3 moderately

4 moderate to medium 5 strong

6 very strong

The evaluation took place immediately after the end of the experiment.

The resistance to chemicals was investigated by means of the BART test. The BART (BASF ACID RESISTANCE TEST) was used to determine the resistance of a clearcoat to acids, alkalis and water droplets. The clearcoat was exposed to a temperature load on a gradient oven after the incineration for 30 minutes at 40 ° C. Previously, the test substances (sulfuric acid 10%, 36% strength, sulfuric acid 6%, hydrochloric acid 10% strength, sodium hydroxide solution 5% strength, VE (= fully demineralized or deionized) water). 1, 2.3 or 4 drops) defined applied with a metering pipette. Following the action of the substances, these were removed under running water and the damage was assessed visually after 24 h in accordance with a predetermined scale:

Grading appearance

0 no defect 1 slight mark

2 markings / matting / no softening

3 Marking / Matting / Color change /

softening

4 cracks / incipient etch 5 clearcoat removed

Each individual mark (spot) was evaluated and the result was recorded in the form of a note for each test substance.

Claims

claims:

1. A thermally curing coating composition based on aprotic Lösemit¬ containing

(A) at least 50 wt .-%, based on the content of non-volatile substances in the coating composition, of a mixture of

(A1) 0 to 50% by weight, based on the totality of the components (A1) and (A2), of a polymethacrylate copolymer containing more than 50% by weight, based on the totality of the comonomers in the Copolymer (A1), free-radically polymerizable, ethylenically unsaturated compounds (a1) having at least one reactive group of the formula I.

-X-SiR "x (OR ') 3-x (I)

R '= hydrogen, alkyl or cycloalkyl, wherein the Kohlenstoffket¬ te may be interrupted by non-adjacent oxygen, sulfur or NRa groups, with Ra = alkyl, cycloalkyl, aryl or aralkyl, X = linear and / or branched alkylene or Cycloalkylene radical having 2 to 20 carbon atoms,

R "= alkyl, cycloalkyl, aryl or aralkyl, where the carbon chain can be interrupted by nonadjacent oxygen, sulfur or NRa groups, x = 0 to 2,

and (A2) 50 to 100% by weight, based on the totality of the components (A1) and (A2), of an adduct of polyisocyanate and alkoxysilane, where (A1) contains at least one reactive group of the formula II:

-NR-C (O) -N- (X-SiR "x (OR ^I ) 3-x) n (X'-SiR" y (OR ^I ) 3-y) m (II)

wherein X and R "represent the structural units described in formula I and with R = hydrogen, alkyl, cycloalkyl, aryl or aralkyl, wherein the

Carbon chain can be interrupted by non-adjacent oxygen, sulfur or NRa groups, with Ra = alkyl, cycloalkyl, aryl or aralkyl, X '= linear and / or branched alkylene or cycloalkylene radical having 2 to 20 carbon atoms, n = 0 to 2, m = 0 to 2, m + n = 2,

(B) a catalyst for the cross-linking of the -Si (OR ') 3-x-

Units, and

(C) an aprotic solvent or a mixture of aprotic solvents.

2. Coating composition according to Claim 1, characterized in that the compound (A1) comprises a polymethacrylate copolymer containing more than 60% by weight, based on the totality of the comonomers in the copolymer (A1), of free-radically po - lymerisierbaren, ethylenically unsaturated compounds (a1).

3. Coating composition according to one of claims 1 or 2, da¬ characterized in that that X and / or X 'is alkylene having 2 to 4 carbon atoms.

4. Coating composition according to one of claims 1 to 3, characterized in that the proportion of the components (A1) and (A2), based on the content of nonvolatile substances in the coating agent Be¬, at least 60 wt .-% is.

5. Coating composition according to one of claims 1 to 4, characterized in that the Katalaysator (B) from the group of boron, aluminum, titanium and / or zirconium chelates, -alcoholates and / or esters and / or which is selected from the group of nanoparticles of compounds of the elements aluminum, silicon, titanium and / or zirconium.

6. Coating composition according to one of claims 1 to 5, characterized in that the aprotic solvent (C) has a water content of not more than 1 wt .-%, based on the solvent, having.

7. Coating composition according to one of claims 1 to 6, characterized in that the solids content of the Beschichtungs¬ medium> 50 wt .-% is.

8. Use of the coating composition according to claims 1 to 7 for the coating of plastics.

9. Multi-stage coating process, characterized in that on a possibly pre-coated substrate, a pigmented base-layer pigment and then a layer of the Coating composition according to one of claims 1 to 7 aufgetra¬ conditions.