MXPA98002860A - Coloid metalic oxides presenting gruposisocianato bloquea - Google Patents

Abstract

The invention relates to colloidal metal oxides, which have blocked isocyanate groups and to their use for the preparation of scratch-resistant coatings on substrates of any type.

Description

COLOID METAL OXIDES PRESENTING BLOCKED ISOCIA-NATO GROUPS. Field of the invention. The invention relates to colloidal metal oxides, which have blocked isocyanate groups, and to their use for the production of scratch-resistant coatings on substrates of any type. There is a great need for scratch-resistant coatings for sensitive surfaces. Especially the thermoplastics, which are characterized by high dimensional toughness, transparency and stability, often have only a low resistance to scratches and chemicals. Description of the prior art. To improve the scratch resistance in the thermoplastics, thermosetting silicone varnishes are preferably used, which are preferably crosslinked by means of a condensation reaction to give Si-O-Si bonds. Parallel to this, other crosslinking mechanisms can also be developed. Such coating systems are often based on condensation products - partial hydrolysis of alkyl- or aryltrial-coxysilane, which are usually combined with colloidal silica sols. Such coating systems are described, for example, in US Pat. Nos. 3 790 527, 3 887 514, 4 243 720, 4 278 804, 4 419 405, 4 624 870, 4 680 232, 4 006 271, 4 476 281 in DE-A 4 011 045, 4 122 743, 4 020 316, 3 917 535, 3 706 714, 3 407 087, 3 836 815, 2 914 427, 3 135 241, 3 134 777, 3 100 532, 3 151 350 in DE-A 3 005 541, 3 014 411, 2 834 606, 2 947 879, 3 016 021. Varnishes often have only a slight elasticity, which allows only thin layer sensors in the range below 10 μm. In addition, the low organic content conditions poor adhesion, which, in most cases, requires the application of a base coat, as well as incompatibilities with organic binders. In addition, a long chilling time is often required for the condensation crosslinking, which may require several hours depending on the sensitivity to the temperature of the substrate. Detailed description of the invention. The task now was to develop a scratch-resistant elastic coating system, which could be applied with high layer thicknesses and which, without a base layer, had good adhesion to the substrate, without having to accept losses relative to the substrate. other properties such as scratch resistance and stability with respect to chemicals. It has now surprisingly been found that colloidal metal oxides, which have blocked isocyanate groups, can be used for scratch-resistant coatings and provide, without a base coat, hard coatings with high resistance to chemicals and excellent adhesion to the substrate. . The application can be carried out according to the usual coating techniques for blocked isocyanates. The subject of the invention are colloidal metal oxides, which have blocked isocyanate groups, which can be obtained by the reaction of A) silanes containing blocked isocyanate groups of the formula (I) XYZSÍ- (CH2) n-NR-CO-NH-Q (I), wherein R means an organic radical with 1 to 40 carbon atoms or hydrogen, XYZ means organic radicals, the same or different, inert below 100 ° C versus isocyanate groups, with 1 to 30 carbon atoms, with the condition that at least one of these residues means an alkoxy group with 1 to 4 carbon atoms, and n means the numbers 2, 3 or 4, and Q means an organic residue, which has at least one isocyanate group, reacted with a blocking agent, with B) colloidal metal oxides selected from the group consisting of Al, Si, Ti, Ta, W, Hf, Zr, Sn and Y. The compounds of the formula (I) are preferably used according to the invention, which, R means an alkyl moiety with 1 to 20 carbon atoms straight or branched, that present a slight tendency to crystallization. Very particularly preferred are compounds of the formula (I), in which R means -CH (COOR1) CH2COOR2, and R1 and R2 mean identical or different organic radicals, alkyl having 1 to 18 carbon atoms and aryl-alkyl with 6 to 14 carbon atoms, inert against the isocyanate below 100 ° C. These compounds have a slight tendency to crystallization and have the advantage that the preparation can be perfectly controlled without solvents. Preference is given to using polyisocyanates and esters of aspartic acid of the formula (II) XYZY- (CH2) n-NH-CH (COOR1) CH2COOR2 (II), in which R1 and R2 and n have the indicated meaning. Its synthesis has been described, for example, in EP-AS 596 360. According to the reaction temperature, the formation of idantoin with dissociation of alcohol can also occur, as described, for example, in US Pat. No. 3,449,599. Another object of the invention is the use of metal oxides , modified according to the invention, as components or as an intermediate for the production of polyurethane synthetic materials, if appropriate foamed, varnishes or coating agents. The colloidal metal oxide according to the invention can be used alone or in part, for example, as a hardener against the components which are reactive with the isocyanate. Colloidal metal oxides will be used as components of the coating agent according to the invention. The expression "colloidal metal oxide" in the meaning of the invention should encompass a broad plurality of finely divided oxides of the elements aluminum, silicon, titanium, zirconium, tantalum, tungsten, hafnium, tin and yttrium in any solvent.

Preference will be given to colloidal silicon oxide. In this case, it is generally a dispersion of particles of silicon dioxide (SiO2) of submicron size in an aqueous or other solvent. The colloidal silicon oxide can be obtained in various forms. Organic solutions of colloidal silica sols will be used in a particularly preferred manner. In this case, as a rule, it is a 30-40% solution of colloidal silicon oxide in isopropanol with a water content of < 1% and with a particle size of 10-12 nm. You can also find application of aqueous solutions of colloidal silicon oxide. Acid forms (ie, dispersions with a low sodium content) will preferably be used for the purpose of the present invention. The alkaline colloidal silicon oxide can be transformed into acid colloidal silicon oxide by acidification. A perfectly suitable aqueous acid colloidal silicon oxide is, for example, Nalcoag 1034A *, obtainable from Nalco Chemical Company, Chicago 111 *, Nalcoag 1034A *. It is an aqueous dispersion, of high purity, of colloidal silicon oxide with a small Na content, a pH value of 3.1 and an SiO2 content of 34% by weight. Of a comparable and equally suitable quality is the LUDOX TMA® dispersion of the DuPont company, which also has a pH value of 3.1 and contains 34% by weight of SiO2. The silanes containing blocked isocyanate groups of the formula (I) are prepared by reaction of alkoxysilyl aminofunctional compounds of the formula (III) XYZSÍ- (CH2) n-NHR (III) wherein n means the numbers 2, 3 or 4, preferably 3 and R means hydrogen or preferably a linear or branched alkyl radical having 1 to 4 carbon atoms. Examples of alkoxysilyl aminofunctional compounds which can be used are 3-amino-propyldimethoxysilane, amino-propyltriethoxysilane or 3-aminopropyl-methyl-diethoxysilane. Examples of alkoxysilyl compounds preferably employed with secondary amino functions are N-methyl-3-amino-propyltrimethoxysilane, N-butyl-3-aminopropyltrimethoxysilane or N-phenyl-3-aminopropyltrimethoxysilane. The alkoxysilyl amino-functional compounds which are used with particular preference according to the invention are those described in EP-A 596 360 of formula (II): XYZSi- (CH2) n-NH-CH (COOR1) CH2COOR2 (II), wherein R1 and R2 mean identical or different organic radicals, inert below 100 ° C, relative to the isocyanate groups, preferably they mean the same or different alkyl radicals with 1 to 4 carbon atoms, particularly preferably radicals respectively methyl or ethyl radicals, X is preferably an alkoxy group with 1 to 4 carbon atoms, particularly preferably methoxy or ethoxy, Y and Z are preferably identical or different radicals and represent alkyl or alkoxy groups with 1 to 4 carbon atoms. carbonphenoxy or ethoxy are particularly preferred, so that X = Y = Z, and n means 2 or 3 or 4, preferably means 3. These compounds represent binding members between the inorganic part and the polyurethane part, since the conversion with isocyanates allows a perfectly controllable reaction without, as occurs for example in the case of aminosilanes, insoluble ureas are formed. According to the conduct of the reaction, the formation of idantoin with alcohol dissociation may occur as described in US-A 3 549 599. Examples of such compounds are N- (3-trimetho-xisylpropyl) diethyl asparaginate, N- (3-triethoxysilyl-propyl) diethyl asparaginate, N- (3-trimethoxysilylpropro) dimethyl asparaginate, N- (3-triethoxysilylpropyl) as-dimethyl para-pentate, N- (3-trimethoxysilylpropyl) aspara-ginate dibutyl, N- (3-triethoxysilylpropyl) dibutyl asparaginate, among which N- (3-trimethoxysilylpropyl) asparaginate dimethyl, N- (3-triethoxysilylpropyl) asparaginate dimethyl, N- (3-trimethoxysilylpropyl) are particularly preferred. ) diethyl asparaginate and N- (3-triethoxysilylpropyl) diethyl asparaginate. By way of other components, hydrolysable silanes can be used concomitantly. Preference is given to the silanes of the formula (IV) SiXnR14.n (IV), wherein the X groups, which may be the same or different, mean hydrogen, halogen, alkoxy, acyl xi, alkylcarbonyl, alkoxycarbonyl with 1 to 4 carbon atoms respectively, or NR22 (R2 = H and / or alkyl with 1 to 4 carbon atoms) and the radicals R 1, which may be the same or different, mean hydrogen, alkyl having 1 to 4 carbon atoms, alkenyl with 2 to 6 carbon atoms, alkynyl with 2 to 6 carbon atoms, aryl with 6 to 24 carbon atoms, arylalkyl with 7 to 30 carbon atoms, arylalkenyl, alkenylaryl, arylalkynyl or alkynylaryl with 8 to 30 carbon atoms respectively, these residues may be interrupted by 0 or S atoms or by the group -NR2 and being able to carry one or more substituents from the group consisting of halogen and by the optionally substituted groups, amino, amido, aldehyde, keto, alkylcarbonyl, carboxy, mercapto, cyano, hydroxy, alkoxy, alkoxycarbonyl, sulphonic, phosphonic, acryloxy, methacryloxy, epoxy or vinyl and n has the value 1, 2 or 3, and / or an oligomer derived therefrom, in an amount of 25 to 95% in moles, based on the total number of moles of the starting components (monomers). Examples of such silanes are tetrametoxisila-not, tetraethoxysilane, methyltrichlorosilane, metiltrimeto-xisilano, methyltriethoxysilane, ethyltrichlorosilane, ethyl triethoxysilane, isobutyltrimethoxysilane, octiltrimetoxi-silane, octyltriethoxysilane, octadeciltrimetilsilano, vi-niltrietoxisilano, vinyl-tris (2-methoxyethoxy) silane, vi -niltriclorosilano, allyltrimethoxysilane, aliltrietoxisi-Lano, propyltrimethoxysilane, phenyltrimethoxysilane, phenyl triethoxysilane, dimethyldichlorosilane, dimetildimetoxisi-Lano, di ethyldiethoxysilane, diphenyldichlorosilane, diphenyldichlorosilane, diphenyldimethoxysilane, difenildietoxi silane, t-butyldimethylchlorosilane, alildimetilclorosi-Lano, 3-chloropropyl trimethoxysilane, 3-cyanopropyl-tri-methoxysilane, [3- (trimethoxysilyl) -propyl] methacrylate, 3- [2,3-epoxy-propoxy) propyl] -trimethoxysilane, 3- [2, 3- (epoxy-propoxy) -propyl] -triethoxysilane, 3-aminopro-p-trimethoxysilane, 3-aminopropyl-triethoxysilane, 3-aminopropyl-methyldiethoxysilane, 3-aminopropyl-methyldim ethoxy-silane, N- [3- (trimethoxysilyl) -propyl] -ethylenediamine, 1N- [3- (trimethoxysilyl) -propyl] -diethylenetriamine, [2- (3,4-epoxycyclohexyl) -ethyl] -trimethoxysilane, N- (3-trimethoxy-silyl-propyl) -aniline, bis- (3-trimethoxysilyl-propyl) amine, 3-mercaptopropyl-trimethoxysilane, N- (3-trimethoxysilyl-propyl) -urea. These silanes are partly commercial products and can be prepared according to known methods. See W. Noli, "Chemie und Technologie der Silicone", Verlag Chemie GmbH, Weinheim / Bergstrasse (1968). Other constituent components are compounds of any type that contain isocyanate groups. Preferred are diisocyanates, known per se, such as, for example, those described in "Methoden der organischen Chemie" (Houben-Weyl), volume 14/2, Georg Thieme Verlag, Stuttgart 1963, pages 61 to 70, and Sief in Liebigs Annalen der Chemie, 562, pages 75 to 136. The diisocyanates to be used preferably according to the invention are 4,4'-diisocyanatodicyclohexylmethane, 3-isocyanatomethyl-3,3,5-trimethylcyclohexylisocyanate ( isophorone diisocyanate = IPDI), tetra-methylene diisocyanate, hexamethylene diisocyanate (HDI), 2-methyl-pentamethylene diisocyanate, 2, 2,4-trimethylhexa-methylene diisocyanate (THDI), dodecamethylene diisocyanate, 1,4-diisocyanato-cyclohexane, 4,4'-diisocyanato-3,3'-dimethyl-dicyclohexylmethane, 4,4'-diisocyanatodi-cyclohexylpropane- (2,2), 3-isocyanatomethyl-1-methyl-isocyanatocyclohexane (IMCI), 1, 3 -diisocyanate-4-methylcyclohexane, 1,3-diisocyanato-2-methyl-cyclohexane, a £, c., a £ 'a'-tetramethyl-m- or -p-xylylene-diisocyanate (TMXDI) as the mixtures constituted by these compounds, diisocyanates easily obtainable industrially such as 2,4- and 2,6-diisocyanatotoluene or 4-diisocyanate, 4'- and, if appropriate, 2,4'-diisocyanatodiphenylmethane, 3,4-diisocyanato-4-methyl-diphenylmethane and its isomers or mixtures of these isomers. The sterically hindered phenylene diisocyanates can be used by alkyl substituents, such as, for example, l-methyl-3,5-diethyl-2,4-diisocyanatobenzene, l-methyl-3,5-diethyl-2,6-diisocyanatobenzene, and arbitrary mixtures of these two diisocyanates, 1, 3, 5-triisopro-pyl-2,4-diisocyanatobenzene or alkyl-substituted phenylene diisocyanates of the type described, for example, in US-A 3 105 845 or DE-A 3 317 649. The diisocyanates to be used with particular preference are 4,4'-diisocyanatodicyclohexylmethane, 3-isocyanatomethyl-3, 3, 5-trimethylcyclohexylisocyanate (isophorone diisocyanate = IPDI), tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), 2-methyl-pentamethylene diisocyanate, 2,2,4-trimethylhexa-methylene diisocyanate (THDI), dodecamethylene diisocyanate, 1,4-diisocyanato-cyclohexane, 4,4'-diisocyanato-3, 3'-dimethyl -dicyclohexylmethane, 4,4'-diisocyanatodi-cyclohexylpropane- (2,2), 3- or 4-isocyanate 1-methyl-1-isocyanatocyclohexane (IMCI), 4-isocyanatomethyl-1, 8-diisocyanatoctane, 1,3-diisocyanato-4-methyl-cyclohexane, 1,3-diisocyanate-2 methyl-cyclohexa-no, a, a, a ', a'-tetramethyl-m- or -p-xylylene-diisocyanate (TMXDI) as well as the mixtures constituted by these compounds. Hexamethylene diisocyanate (HDI) is very particularly preferred. It is also possible to employ or use concomitantly various accessible polyisocyanates from the aforementioned diisocyanates, such as those described, for example, in J. prakt. Chem. 1994, 336, 185-200. Other constituent components to be used concomitantly, if appropriate, are compounds of any type, common in the chemistry of polyurethanes, reagents against isocyanate groups, such as, for example, polyester polyols, polycarbonate or polyether polyols or else diols of low molecular weight such as, for example, ethylene glycol, propylene glycol, 1,4- and 1,3-butanediol, 1,6-hexanediol, 1,8-octanediol, neopenitylglycol, 2-methyl-1,3-dihydroxypropane, glycerin, trimethylolpropane , diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol with the aforementioned molecular weight range, dipropylene glycol, tripropylene glycol or arbitrary mixtures of such alcohols. According to the invention, the concomitant use of blocking agents is essential. By this step isocyanate groups are protected against the reactive solvents with respect to the isocyanate, which will be used subsequently for the crosslinking reaction. Suitable blocking agents are, in particular, compounds with preferably a group reactive towards the isocyanate, which are involved in an addition reaction with organic isocyanates. Suitable blocking agents of this type are, for example, secondary or tertiary alcohols, such as isopropanol or t. butanol, CH-acid compounds, such as for example diethyl malonate, acetylacetone, ethyl acetoacetate, oxy acetates, such as for example formaldoxime, acetaldoxime, methyl ethylketoxime, cyclohexanone oxime, acetophenone oxime, benzo-phenone oxime, or diethylene glyoxime, lactams, such as for example caprolactam, valerolactam, butyrolactam, phenols such as phenol, o-methylphenol, N-alkylamides, such as for example N-methylacetamide, imides, such as phthalimide, secondary amines, such as for example diisopropylamine, imidazole, pyrazole, , 5-dimethylpyrazole, 1,2,4-triazole and 2,5-dimethyl-l, 2,4-triazole. Preference is given according to the invention to blocking agents such butanone oxime, 3,5-dimethylpyrazole, caprolactam, diethyl malonate, dimethyl malonate, ethyl acetoacetate, 1,2,4-triazole and imidazole. Especially preferred are blocking agents which enable a low set temperature such as, for example, diethyl malonate., dimethyl malonate, butanone oxime and 3,5-dimethylpyrazole, which also conditions a yellowish bass. The production can be carried out according to various variants. The preferred variant consists in the reaction of an alkoxysilyl functional prepolymer with the colloidal metal oxide in an alcoholic solution with the addition of water and optionally of catalysts. In this case, a prepolymer is first prepared from a polyisocyanate or a mixture of polyisocyanates, the alkoxysilyl functional amine and a blocking agent and, if appropriate, chain extenders employed concomitantly, of the type indicated above. The preparation can be carried out by adding the blocking agent and the alkoxysilyl functional amine to the polyisocyanate, optionally prolonged. The reaction is carried out in such a way that, in the first place, from 0.1 to 0.9 equivalents of NCO, preferably from 0.3 to 0.7 equivalents of NCO, are reacted with a blocking agent, from 0 to 100. ° C, preferably at 20 to 70 ° C and then the remaining NCO groups are saturated, at 0 to 80 ° C, preferably at 20 to 70 ° C, with the alkoxysilyl-functional amine. Of course, it is also possible to react the polyisocyanate firstly, if appropriate previously with polyols, with the alkoxysilyl functional amine and then with the blocking agent. Likewise, the reaction with a mixture of both components is also possible. Solvents of any kind can be used concomitantly. The use of the esters of aspartic acid, alcosilil-functional, has proved to be a great advantage in the preparation, since the reaction develops especially without having to resort to solvents, under perfectly controllable conditions. Above all at high temperatures, which are generally above 60 ° C, the formation of idantoin can occur in this case, which can be an advantage in certain cases. The preparation of the modified colloidal metal oxide can be carried out by mixing the aforementioned prepolymer with the dissolved colloidal metal oxide and optionally with the silane. If a metal oxide dissolved in organic products is used, at least a quantity of water should be added such that the hydrolysis of the alkoxysilyl group can be carried out. If colloidal aqueous solutions of the metal oxide are used, at least a quantity of organic solvent will have to be added such that the polymer can be dissolved. It has been observed within the scope of the present invention that at least 20% of a secondary alcohol has to be added to prevent gel formation. If necessary, a catalyst for acceleration can be added. In this case, the addition of acids such as hydrochloric acid, sulfuric acid or trifluoroacetic acid is preferred. To complete the reaction, it can be stirred for a long time at room temperature or it can also be heated to reflux. To increase the solids content, the solvent and / or excess water can be removed by distillation. Solutions prepared in this way of colloidal metal oxides, containing blocked isocyanate groups, can be combined with at least difunctional substances, of any type, reactive with isocyanate groups, for the preparation of coating agents. The proportion of blocked isocyanate groups with respect to the groups reactive towards the isocyanate groups will usually be chosen between 0.5 and 1.5, preferably between 0.8 and 1.2. Of course, the hardeners described here can also be used concomitantly, also as additives in formulations of any type, which contain groups reactive towards the isocyanate groups. Another object of the invention is the use of colloidal metal oxides which have blocked isocyanate groups as coating agents resistant to scratching for any type of substrate. The coating agents obtained can be used for the coating of any type of substrates to improve the resistance to scratches, resistance to wear by friction or stability against chemical products. Preferred substrates are thermoplastic synthetic materials such as polycarbonate, polybutylene terephthalate, polymethyl methacrylate, polyethenetene or polyvinyl chloride, with polycarbonate being particularly preferred. The application of the coating agent can be carried out by any type of process such as dipping, spraying and watering. The hardening is carried out by heating under the conditions necessary for the blocked isocyanates and can obviously be accelerated by the addition of suitable catalysts. Examples Obtaining colloidal metal oxides, which have blocked isocyanate groups: Example 1. 84 g (0.5 mol) of hexamethylene diisocyanate are prepared and first reacted with 48 g (0.5 mol) of 3.5 -dimethylpyrazole. Subsequently, 176 g (0.5 mol) of N- (3-trimetho-xysilylpropyl) -dashtyl derivative (prepared according to EP 596 360, Example 5) are added dropwise at 50 ° C. To the prepolymer, heated at 50 ° C, 2050 g of Organosol (Bayer AG, 29.3% colloidal solution of silicon oxide in isopropanol) are added and cooled to room temperature. 20 g of water are added, adjusted to a pH value of 3.1 with trifluoroacetic acid and stirred for 48 hours at room temperature. Then, 1457 g of methoxypropyl acetate are added for the partial exchange of isopropanol by a solvent with a higher boiling point and a solids content of 56% is adjusted by elimination by vacuum distillation at 40 ° C and 70 mbar. The solution of this modified colloidal metal oxide has a blocked isocyanate content of 1.29%. EXAMPLE 2 84 g (0.5 mol) of hexamethylene diisocyanate are prepared and first reacted with 48 g (0.5 mol) of 3,5-dimethylpyrazole. Subsequently, 176 g (0.5 mol) of N- (3-trimethoxysilylpropyl) diastereoseparaginate at 50 ° C are added dropwise. To the prepolymer heated to 50 ° C is added 2.050 g of Organo-sol (Bayer AG, 29.3% colloidal solution of silicon oxide in isopropanol) and cooled to room temperature. 20 g of water are added, a pH value of 3.1 is adjusted with trifluoroacetic acid and stirred for 48 hours at room temperature. Next, 70 mbar isopropanol is distilled off to a solids content of 53%. The solution has a blocked isocyanate content of 1.23%. Example 3. 84 g (0.5 mol) of hexamethyldiisocyanate are placed and reacted first with 48 g (0.5 mol) of 3,5-dimethylpyrazole. Subsequently, 176 g (0.5 mol) of N- (3-trimethoxy-propyl) propyl-diethyl agatinate are added dropwise at 50 ° C. To the prepolymer, heated to 50 ° C, is added 2,563 g of Organosol (Bayer AG, 29.3% colloidal solution of silicon oxide in isopropanol) and cooled to room temperature. 20 g of water are added, adjusted to a pH value of 3.1 with trifluoroacetic acid and stirred for 48 hours at room temperature. The isopropanol is then distilled off at 70 mbar to a solids content of 55%. The solution has a blocked isocyanate content of 1.03%. Example 4. 111 g (0.5 mol) of 3-isocyanato-methyl-3,3,5-trimethylcyclohexyl isocyanate (isophoronadiisocyanate = IPDI) are initially introduced and are reacted with 48 g (0.5 g). moles) of 3,5-dimethylpyrazole. Subsequently, 176 g (0.5 mol) of N- (3-trimethoxysilylpropyl) -saltyrant diasaturase at 50 ° C are added dropwise. To the prepolymer, heated to 50 ° C, is added 2.050 g of Organosol (Bayer AG, colloidal solution to 29.3 of silicon oxide in isopropanol) and cooled to room temperature. 20 g of water are added, a pH value of 3.1 is adjusted with trifluoroacetic acid and stirred for 48 hours at room temperature. Then isopropanol is distilled off at 70 mbar to a solids content of 55%. The solution has a blocked isocyanate content of 1,2. 3 %. Application examples Example 5. To 325 g of the blocked isocyanate of Example 1, 20 g of a caprolactone polyester, initiated on 1,6-hexanediol, with an average molecular weight of 400 d, 72 g of acetone as well as 1.7 g are added. of dilatile of dibu-tilestaño and 0,1% (referred to the solid matter) of extender Baysilone * OL 17 (commercial product of the firm Bayer AG). The coating agent is applied by surface spraying on a polycarbonate plate, previously cleaned with isopropanol (100 x 100 x 3 mm) with a wet film thickness of 50 μm. The thickness of the coating of the scratch-resistant varnish is 20 μm. The hardening takes place after drying for 30 minutes at room temperature by heating for 1 hour at 120 ° C. Example 6. 342 g of the blocked isocyanate of Example 2, 20 g of a caprolactone polyester, initiated on 1,6-hexanediol, with an average molecular weight of 400 d, as well as 1.8 g of dibutyltin dilaurate and 0.1% (based on solid matter) of Baysilone * OL 17. The coating agent is applied by surface spraying on a polycarbonate plate, previously cleaned with isopropanol (100 x 100 x 3 mm) with a wet film thickness 60 μm. The thickness of the scratch-resistant varnish layer is 30 μm. Hardening is carried out after 30 minutes of drying at room temperature, by heating for 1 hour at 120 ° C. Example 7. 20 g of a caprolactone polyester, initiated on 1,6-hexanediol, with an average molecular weight of 400 d, 92 g of acetone as well as 2.1 g of anhydrous, are added to 409 g of the blocked isocyanate of example 1. Diastilene dilaurate and 0.1% (based on solid matter) of Baysilone * OL 17. The coating agent is applied by surface spraying on a polycarbonate plate, previously cleaned with isopropanol (100 x 100 x 3 mm) with a wet film thickness of 50 μm. The thickness of the scratch-resistant varnish layer is 20 μm. Hardening is carried out after drying for 30 minutes at room temperature, by heating for 1 hour at 120 ° C. Example 8. To 341 g of the blocked isocyanate of Example 1, 20 g of a caprolactone polyester, initiated on 1,6-hexanediol, with an average molecular weight of 400 d, 75 g of acetone as well as dibutyltin dilaurate and 0.1% (based on solid matter) of Baysilone * OL 17. The coating agent is applied by surface spraying on a polycarbonate sheet, previously cleaned with isopropanol (100 x 100 x 3 mm Makrolon *, from the Firm Bayer AG) with a wet film thickness of 130 μm. The film thickness of the scratch-resistant varnish is 40 μm. Hardening is carried out after drying for 30 minutes at room temperature, by heating for 1 hour at 120 ° C. Results: Ex. Drying Eßpß- Resis- Estabi- Adhßrßn- Toughness at tem- perature after pendulum septure Secon- ture of the cut-off fronts Kónig ambient / layer scratches to the ace- in DIN 53157 form co mured 120 mm grit ° C ethyl lia lx / 4x [minutes] 5 30/60 20 1 0 0/0 223 6 30/360 30 2 0 0/0 192 7 30/60 20 1 0 0/0 130 8 30/60 40 2 0 0/0 206 Evaluation of scratch resistance after three scrapes with a sample of steel wool with a fineness of (0000): 0 = absence of traces, 1 = hardly any traces are observed, 2 = slightly scratched 3 = scratched moderate 4 = strongly scratched. Determination of the stability against the chemical products after the action of ethyl acetate: 0 = absence of traces, 1 = remaining edges 2 = hardly scratching 3 = scratching 4 = slight swelling, 5 = swelling. Determination of the adhesion according to the grid-cut method in accordance with DIN 53 151. 0 = no delamination until 5 = total delamination. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property:

Claims (1)

CLAIMS 1. - Colloidal metal oxides, which have blocked isocyanate groups, characterized in that they are obtained by the reaction of A) silanes containing blocked isocyanate groups of the formula (I) XYZSÍ- (CH2) n-NR-CO-NH-Q (I), in which R means an organic radical with 1 to 40 carbon atoms or hydrogen, XYZ means organic radicals, the same or different, inert below 100 ° C as opposed to isocyanate groups, with 1 to 30 carbon atoms, with the proviso that at least one of these residues means an alkoxy group having 1 to 4 carbon atoms, and n means the numbers 2, 3 or 4, and Q means an organic residue, which has at least one isocyanate group, reacted with a blocking agent, with B) colloidal metal oxides selected from the group consisting of Al, Si, Ti, Ta, W, Hf, Zr, Sn and Y. 2.- Use of the colloidal metal oxides have isocyanate groups blocked according to the claim 1, as participants in the reaction for compounds reactive towards the isocyanate for obtaining scratch-resistant coatings of thermoplastics. 3. Varnishes containing colloidal metal oxides containing blocked isocyanate groups according to claim

1. RESOLUTION OF THE INVENTION The invention relates to colloidal metal oxides, which have blocked isocyanate groups and to their use for the production of scratch-resistant coatings on substrates of any type.