WO2008145585A1 - Method for distributing silicates in coating compounds - Google Patents

Abstract

The present invention relates to a method for the fine distribution of silicates in coating compounds for use in paints.

Description

 Method for distributing silicates in coating compositions

description

The present invention describes a process for the homogeneous dispersion of inorganic nanoparticles in coating compositions with the aim of improving the scratch resistance of the coatings obtained therefrom.

To incorporate inorganic particles in organic coating compositions, these particles are often prepared as milled or precipitated solids or slurry, and then suspended in the organic coating composition.

The disadvantage of this is that the particles can not be transferred free of agglomerates into an organic matrix by known methods such as dry grinding, wet grinding, ultrasonic treatment or extrusion. In addition, for example, particles dispersed by wet grinding tend to aggregate after removal of the solvent, so that the particles are unevenly distributed when introduced into a medium such as a coating composition. As a rule, this results in a loss of transparency of the coating composition and, due to the phase separation of the coating composition, leads to abrasion-labile coatings with low hardness.

Since it is a particular embodiment of the present invention to use aqueous inorganic nanoparticle sols as inorganic fillers for organic coating compositions, a suitable pretreatment of the particles is required in order to convert them without agglomeration into the organic resin.

Direct suspension of the particles in the aqueous solvent in the organic coating materials is usually impossible due to the incompatibility of the solvents. However, a substantial absence of solvents is required because solvents would be an additional component in the paint system and this would mean separation of the solvent from the end user. We are looking for ready-to-use, low-solvent coating compounds that already contain inorganic particles.

US 3699049 describes the removal of water by distillation at 50 to 100 ⁰ C of acidic or basic, colloidal silica sols with polyfunctional alcohols, such as glycerol.

The disadvantage is that the solvent can not be removed in this method, since the glycerol used in the explicitly disclosed examples has a boiling point of about 290 ⁰ C at atmospheric pressure. This prohibits removal of the solvent under mild conditions. DE 102005018671 describes epoxy resins as adhesives with organosilane-modified silica sols, in particular with epoxy groups-modified silica sols whose surface modification is intended to allow particle aggregation.

EP 75545 A1 describes the preparation of silicate-containing unsaturated polyester resins by distilling off water from acidic silica sols in the presence of building blocks of the polyesters and subsequent addition with free-radically polymerizable monomers.

In this case, a SiO2-filled polyester solid is produced, which is no longer flowable and thus can not be used as a coating material.

DE 69314374 T2 describes the removal of water at temperatures below 55 ⁰ C from acidic silica sols with replacement of water by alkanol acrylates as solvent.

This method is limited to polar compounds such as alkanol acrylates and is limited to unmodified silica sols.

EP 460560 A2 describes starting from alcoholic dispersions of silica sols the surface modification with double bond-containing silanes for use in free-radically polymerizable coating compositions.

This method already starts from silica sols, which are present in alcohols. Such silica sols are less commercially available than aqueous silica sols. In addition, it is not disclosed at which pH the surface modification is carried out. In addition, it is disadvantageous in this reaction procedure that only free silanol groups on the surface of the particles can react with the silanes in anhydrous alcoholic sols. Thus, a condensation reaction, and thus the tendency to aggregate, in alcoholic suspension can be prevented much easier than in aqueous suspension.

EP 1236765 A describes a process in which an alkali silicate solution is acidified with an acidic ion exchanger and converted into a silica sol and surface-modified with a silane and this is then mixed with isopropanol and water is distilled off. The resulting silicates having a particle size of 3 to 50 nm can then be taken up in organic coating compositions. The silica sols prepared are made alkaline after their preparation by acidic polycondensation to protect against agglomeration (paragraph [0042], see also example 1 of EP 13661 12 B1). Subsequently, ie in the alkaline pH range, the surface of the silica sol is optionally modified by reaction with functional silanes. A disadvantage of this production process is that the products thus obtained have a relatively high viscosity. A further disadvantage is that commercially available silicic acid sols which are modified in the alkaline pH range show a marked agglomeration and gelation tendency on addition of alcohols and / or silanes.

WO 2006/044376 describes the preparation of inorganic oxides, in particular silicates in an aqueous medium and subsequent distribution in organic coating compositions. A process disclosed therein (Example 3) comprises, starting from a silica sol, an ion exchange with liberation of the acid, mixing with an organic solubilizer, addition of base and addition of a surface-modification silane. Again, the complete surface modification with the silane takes place in the alkaline pH range. Subsequently, the solvent is removed until dry and taken up in an organic solvent.

A disadvantage of this method is that the resulting solutions of silica sols using commercial silica sols have a high viscosity and also the surface of the particles must be completely reacted with silane to give a free-flowing powder. It is noted that surface treatment with silanes may be under acidic or basic conditions, but only alkaline reaction conditions are explicitly disclosed.

In another method (Example 1), the aqueous Nanosilikatsol is mixed directly with a solubilizer, which can act as a reactive diluent, and the organic coating composition and the water separated by distillation and then taken up with an organic solvent. The surface modification with a silane also takes place here in the alkaline. The disadvantage is that the solubilizer remains in the coating composition and this method is applicable only to those solubilizers that can react simultaneously as reactive diluents.

In a further process (Example 2), another silica sol is functionalized with a functionalized alkoxysilane using a catalyst in the alkaline state. The product is taken up in a large amount of solvent and the catalyst removed by washing. The functionalized silicate is then further used as an organic solution in coating compositions.

A disadvantage of this method is that the catalyst has to be removed from the product in a complicated manner by means of washes in order to stop the reaction. The obtained powders Moreover, they can no longer be completely redispersed, which leads to larger agglomerates in the product and thus to a reduced transparency of the coating.

US 2006/0251901 A1 describes the modification of colloidal silicates with various silanes in the presence of solvents and subsequent separation of water.

In Examples 4 and 5 of US 2006/0251901 A1, acidic colloidal silicates are used and surface-modified with phenyltrimethoxysilane. After a reaction time of 2 hours, the reaction mixture is made basic and the solvent is distilled off.

Although in Example 1 of US 2006/0251901 A1 a methacrylic-containing silane is used as the surface modification agent, the colloidal silicate used is an alkaline silicate.

US 2007/0207410 A1 describes the modification of colloidal silicates with various silanes in the presence of solvents and subsequent separation of water. In Formulation E, a commercial colloidal silicate is first brought to a pH between 2 and 3 and then to a pH between 8 and 9 for surface modification. The surface modification also takes place here in the alkaline medium. In paragraph [0171] it is suggested to bring the silicates to a pH of 8 to 9 for the subsequent surface modification. The implementation in the acidic pH range is not disclosed.

US 2007/0207410 A1 refers to the method according to US Pat. No. 2,001,885, according to which a silica sol is treated with alcohols at a pH of preferably about 3 (column 3, line 41), on the one hand to remove water (column 5, line 66 ff .) and in particular for the surface treatment, in which accessible OH groups on the surface of the sol are esterified with the alcohol (column 4, line 28 ff). Only the reaction with alcohols to modify the surface is disclosed.

US 2007/0207410 A1 also refers to the method according to US Pat. No. 4,522,958, according to which, according to Example 1, an acidic colloidal silicate is mixed with dipropylene glycol monomethyl ether and dehydrated. The product thus obtained is incorporated into an acrylic resin to give a radiation-curable coating composition.

A disadvantage of this method is that only a surface modification takes place by esterification of OH groups on the surface of the silicate with the alcohol of the solvent. This alcohol has no radiation-curable groups that allow reaction with the radiation-curable medium. US 6136912 and US 6825239, the separation of water with the aid of alcohols from aqueous silica sols at a pH of 1 to 3 with simultaneous reaction with a vinyl silane in amounts of 0.01 to 0.1 mmol / m ² surface or 0.01 to 1 g / g and subsequent mixing with multifunctional (meth) acrylates. The silica sols can be prepared by acidification of commercially available alkaline silica sols.

The disadvantage of this is that vinyl silanes have a relatively low reactivity in the UV polymerization reaction, so that the crosslinking density in the resulting coatings remains lower. Another disadvantage is that stability and viscosity of products modified with a vinyl silane are not yet optimal.

The object of the present invention was to provide coating compositions with low viscosity which contain finely divided silicates prepared from cost-effective commercial products, the silicates being to be distributed uniformly in the coating composition. The surface modification should be done with as little agent as possible.

The object has been achieved by a process for the preparation of silicate-containing organic coating compositions, comprising the steps

- Adding an aqueous silica sol (K) having an average particle diameter of 5 to 150 nm with a content of silica, calculated as Si02, from 10 to 60% by weight with a pH of 2 to 4 with the 0 to 10-fold amount of water (based on the set content of SiO 2) and 0.1 to 20 times the amount (based on the set content of SiO 2) at a temperature of 10 to 60 ⁰ C at least one organic solvent (L), selected from the group consisting of ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 1-chloro-2-propanol, cyclopentanol, cyclohexanol, 1, 4-dioxane, Tetrahydrofuran, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 2-ethoxyethanol, 2-methyl-2-propanol, 2-methoxyethanol, dimethylformamide, acetonitrile and acetone,

at least one compound (S) which has at least one at least monoalkoxylated silyl group and at least one group which is reactive with the organic coating composition in an amount of from 0.1 to 20 μmol per m ² surface area of (K), and optionally further solvent (L),

- placing the mixture thus obtained with the organic coating composition and

- At least partial distillation of the organic solvent (L).

The aqueous colloidal solution (K) of polysilicic acid particles (silica sol) contains particles having an average particle diameter of from 1 to 150 nm. preferably 2 to 120, particularly preferably 3 to 100, very particularly preferably 4 to 80, in particular 5 to 50 and especially 8 to 40 nm.

The content of silica, calculated as SiO 2, is from 10 to 60% by weight, preferably from 20 to 55, particularly preferably from 25 to 40% by weight. It is also silica sols can be used with a lower content, but the excess water must then be separated by distillation in a later step.

The aqueous solutions (K) are colloidal solutions of polyalkanoic acid, which may contain a small proportion of alkali metal, alkaline earth metal, ammonium, aluminum, iron (II), iron (III) and / or or zirconium ions, preferably alkali metal, alkaline earth metal, ammonium and / or iron (II) ions, particularly preferably alkali metal, alkaline earth metal and / or ammonium ions, very particularly preferably alkali metal and / or alkaline earth metal ions and in particular re alkali metal ions.

Among the alkali metal ions, sodium and / or potassium ions are preferred, with sodium ions being particularly preferred.

Among the alkaline earth metal ions, magnesium, calcium and / or beryllium ions are preferred, magnesium and / or calcium ions are particularly preferred, magnesium ions are very particularly preferred.

The molar ratio of metal ions to silicon atoms in (K) is from 0: 1 to 0.1: 1, preferably from 0.002 to 0.04: 1.

After adjusting the pH, the silica sols (K) used have a pH of the aqueous phase of from 2 to 4, preferably from 2 to 3.

Under an aqueous colloidal solution, a solution of optionally stabilized silica particles which have a mean particle diameter between 1 and 150 nm in this document, which does not settle even when storing for a period of one month at 20 ⁰ C.

By SOI is meant in this document a colloidally disperse, incoherent (i.e., each particle is freely mobile) solution of a solid in water, here as silica sol a colloidally disperse solution of silica in water.

The acidic aqueous silica sols (K) used according to the invention can be obtained, for example, in three different ways:

by acidification of the corresponding alkaline silica sols,

by production from low-molecular silicas, preferably water glass, ie salt-like particles with a diameter below 1 nm, or - by condensation of esters of low molecular weight silicas.

The aqueous solutions of alkaline silica sols generally have a pH of from 7 to 11, preferably from 8 to 11, more preferably from 8 to 10 and most preferably from 9 to 10. These alkaline silica sols are commercially available and thus represent a readily available and preferred starting material for the process according to the invention.

The particles in these alkaline silica sols usually have an average particle diameter of 1 to 150 nm, preferably 2 to 120, particularly preferably 3 to 100, very particularly preferably 4 to 80, in particular 5 to 50 and especially 8 to 30 nm.

The content of silica, calculated as SiO 2, is from 15 to 60% by weight, preferably from 20 to 55, particularly preferably from 25 to 40% by weight. It is also possible to use alkaline silica sols with a lower solids content, but the excess water content must then be removed by distillation in a later step.

The alkaline silica sols can be stabilized with the above metal ions.

The molar ratio of metal ions to silicon atoms in (K) is from 0: 1 to 0.1: 1, preferably from 0.002 to 0.04: 1.

The pH of these alkaline silica sols is generally at least 8, preferably 8 to 12, particularly preferably 8 to 11 and very particularly preferably 8 to 10.

The silica sols (K) to be used according to the invention are prepared from these alkali silicas by adjusting the desired pH in these silica sols, for example adding mineral acids or adding the alkaline silica sols with an ion exchanger.

Acidification can be carried out with any acids, preferably with hydrochloric acid, salicylic acid, phosphoric acid, sulfuric acid, acetic acid, formic acid, methylsulfonic acid, para-toluenesulfonic acid or else by addition with an acidic ion exchanger, preferably by acidification with hydrochloric acid, nitric acid, phosphoric acid, Sulfuric acid or acetic acid, particularly preferably with hydrochloric acid, nitric acid or sulfuric acid, and very particularly preferably by acidification with sulfuric acid. It is a preferred embodiment to prepare the silica sols (K) by adding alkaline silica sols with an ion exchanger. This has the consequence that in the silica sols (K) the electrolyte content is low, for example less than 0.2% by weight and preferably less than 0.1% by weight.

Electrolytes are understood to mean other inorganic ionic constituents than silicates, hydroxides and protons. These electrolytes, which originate predominantly from the stabilization of the alkaline silica sols, are added to the suspension in order to stabilize the particles after their preparation.

Also conceivable is the preparation of the silica sol (K) from water glass by acidification, for example with an ion exchanger or by adding mineral acid. The water glass used for this is preferably potassium silicate and / or sodium silicate, which is particularly preferably a ratio of 1-10 mol of SiO 2 to 1 mol of alkali oxide, very particularly preferably 1.5-6 and in particular 2-4 mol of SiO 2 to 1 mol of alkali oxide having.

In this case, the reaction mixture is allowed to react until a silica sol (K) of the desired size is formed, and then proceeds to the process of this invention.

The low molecular weight silicic acids (ortho- and oligosilicic acid) are normally stable only in highly dilute aqueous solutions with a content of a few% by weight and are usually concentrated before further use.

Furthermore, the preparation of the silica sols (K) can be carried out by condensation of esters of low molecular weight silicic acids. These are usually d- to C ₄ -AlkVl-, especially ethyl esters of oligo- and especially orthosilicic acid, which form in acidic or basic silica sols (K).

In order to functionalize the surface of the SiO 2 nanoparticles, the resulting acidified solution is reacted with 0 to 10 times, preferably 0.2 to δ times, particularly preferably 0.4 to 3 times and very particularly preferably 0.5 to 2 times the amount of water (based on the amount of silica sol used) and 0.1 to 20 times, preferably 0.3 to 10 times, more preferably 0.5 to δfachen and most preferably 1 to 2 times the amount (based on the amount of silica sol used) added to at least one organic solvent (L). A preferred embodiment is to add no additional water.

The solvent (L) can be added to the reaction mixture before or during the reaction with the silane (S), preferably before or during and more preferably before the reaction with the silane. The organic solvent (L) is selected according to the following criteria: Under the mixing conditions, it should have both sufficient miscibility with water and miscibility with the organic coating.

The miscibility with water under the reaction conditions should be at least 20% by weight (based on the finished water-solvent mixture), preferably at least 50% by weight and particularly preferably at least 80% by weight. If the miscibility is too low, there is a risk that a gel will form from the modified silica sol or larger granules of nanoparticles will flocculate.

The coating composition should be completely soluble in the solvent (L) or the water-solvent mixture.

Furthermore, the solvent (L) should have a boiling point of less than 80 ⁰ C in a pressure range of atmospheric pressure to 50 hPa, so that it is easily separable by distillation.

In a preferred embodiment, the solvent (L) forms an azeotrope or heteroazeotrope with water under the conditions of the distillation, so that the distillate forms an aqueous and an organic phase after the distillation.

Examples of suitable solvents (L) are ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 1-chloro-2-propanol, cyclopentanol, cyclohexanol, 1, 4-dioxane, tetrahydrofuran, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 2-ethoxyethanol, 2-methyl-2-propanol, 2-methoxyethanol, dimethylformamide, acetonitrile and acetone.

It may be a preferred embodiment to add water and solvent (L) simultaneously to the solution of the silicate, and it may also be useful to add water and solvent (L) premixed with each other.

The addition of water and solvent (L), or their mixture, can be carried out in one pour, in portions or continuously.

As a result of this measure, depending on the pretreatment of the brine, agglomeration of the silicate particles can be reduced or preferably even prevented.

According to the invention at least one compound (S) is added to the reaction mixture, the at least one, preferably exactly one at least once, for example, one to three, preferably exactly triply alkoxylated silyl group and at least at least one, preferably has exactly one group which is reactive with the organic coating composition.

Among alkoxylated silyl groups are groups

(R ¹ -O-) _n -Si

understood in which

R ^{1 is} Ci to C ₂ o-alkyl, preferably Cibis C ₄ alkyl and n is an integer from 1 to 3, preferably 3.

Examples of C 1 - to C 20 -alkyl are methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-hexyl, n-heptyl, n-octyl, 2- Ethylhexyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl and n-eicosyl.

Examples of C 1 to C 4 -alkyl are methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

Preferred radicals R ¹ are methyl, ethyl, n-butyl and tert-butyl, more preferably methyl and ethyl.

Groups which are reactive with the organic coating composition are those which have a same or complementary group as the binder-crosslinker combination of the organic coating composition.

This means hydroxy, epoxy, amino or acid groups in the case of epoxy resins or melamine-formaldehyde resins, hydroxy, amino or isocyanate groups in the case of polyurethane resins or radically polymerizable groups in the case of radiation-curable resins.

Free-radically polymerizable groups are, for example, allyl ether, vinyl ether, acrylate or methacrylate groups, preferably vinyl ether, acrylate or methacrylate groups and particularly preferably acrylate or methacrylate groups, which are referred to briefly as (meth) acrylate groups in this document.

These reactive groups are usually connected by spacer groups with the silyl groups. Such spacer groups are divalent organic radicals having 1 to 20 carbon atoms, for example alkylene or arylene groups, preferably alkylene groups. Examples of these are methylene, 1,2-ethylene (-CH ₂ -CH ₂ -), 1, 2-propylene (-CH (CH ₂ ) -CH ₂ -) and / or 1, 3-propylene (-CH ₂ -CH ₂ -CH ₂ -), 1, 2, 1, 3 and / or 1, 4-butylene, 1, 1-dimethyl-1, 2-ethylene, 1, 2-dimethyl-1, 2-ethylene, 1 , 6-hexylene, 1, 8-octylene or 1, 10-decylene, preferably methylene, 1, 2-ethylene, 1, 2 or 1, 3-propylene, 1, 2, 1, 3 or 1, 4 Butylene, particularly preferably methylene, 1, 2-ethylene, 1, 2 and / or 1, 3-propylene and / or 1, 4-butylene and most preferably methylene, 1, 2-ethylene, 1, 2 and / or 1, 3-propylene.

Preferred compounds (S) are, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, isooctyltrimethoxysilane, N- (3)

Triethoxysilylpropyl) methoxyethoxyethoxyethyl carbamate (PEG3TES), N- (3-triethoxysilylpropyl) methoxyethoxyethoxyethyl carbamate (PEG2TES), 3- (methacryloyloxy) propyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3- (methacryloyloxy) propyltriethoxysilane, 3- (methacryloxy) methyltriethoxysilane, 3- (methacryloxy) ethyltriethoxysilane, 3- (methacryloxymethyl) methyldimethoxysilane, 3- (methacryloxymethyl) methyldiethoxysilane, 3- (methacryloxy) propylmethyldimethoxysilane, 3- (acryloxypropyl) methyldimethoxysilane, 3- (methacryloxy) propyldimethylethoxysilane, 3- (methacryloxy) propyldimethylethoxysilane, vinyldimethylethoxysilane lan, vinylmethyldiacetoxysilane, vinylmethyldiethoxysilane, vinyltriacetoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriphenoxysilane, vinyltri-t-butoxysilane, vinyltrisisobutoxysilane, vinyltriisopropenoxysilane, vinyltris (2-methoxyethoxy) silane, 3- (N-allylamino) -propyltrimethoxysilane, 3 (N-allylamino) - propyltriethoxysilane, styrylethyltrimeth oxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethylimethoxysilane, 3-aminopropyldimethylmethoxysilane, 3-aminopropyldimethylethoxysilane, N- (2'-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2'-aminoethyl) -3- aminopropylmethyldiethoxysilane, N- (2'-aminoethyl) -3-aminopropylmethoxysilane, N- (2'-aminoethyl) -3-aminopropylethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane or 3- glycidoxypropyltrimethoxysilane.

Preferably, the compounds (S) are 3- (methacryloxy) propyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3

(Methacryloxy) propyltriethoxysilane or 3- (methacryloxy) propylmethyldimethoxysilane.

According to the invention it is crucial that the reaction of the silica sol (K) with at least one compound (S) takes place in a pH range which corresponds to the isoelectric point of the silica sol used ± a pH unit. In most cases, this is a pH of 2 to 4. Acidification can be carried out with any acids, preferably with hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, acetic acid, formic acid, methylsulfonic acid, para-toluenesulfonic acid or else by passing over acidic ion exchangers, preferably by acidification with hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid , Acetic acid or ion exchangers, particularly preferably with hydrochloric acid, nitric acid, sulfuric acid or ion exchangers, and very particularly preferably by acidification with sulfuric acid or ion exchangers.

By reaction with the compound (S), the surface of the silica sol (K) used is modified so that the compatibility between the originally polar silica sol and the mostly non-polar coating composition is improved. At the same time, complete modification of the surface, as described in WO 2006/044376, brings no further advantages.

Therefore, it is sufficient according to the invention if (S) is used in an amount of 0.1 to 20 μmol per m ² surface area of (K), preferably in 0.25 to 15, particularly preferably 0.5 to 10 and very particularly preferably 1 to 8 μmol per m ² surface area of (K).

This usually corresponds to an amount of 0.01 to 5 mmol (S) per gram (K), preferably 0.05 to 4 mmol (S) per gram (K) and particularly preferably 0.1 to 3 mmol (S) per gram (K).

The reaction is preferably carried out in a manner such that not more than 20 mol% of the silane (S) used remain unreacted in the reaction mixture, preferably not more than 15 mol%, more preferably not more than 10 mol% and most preferably not more than 5 mol%.

For this, the reaction with (S) is carried out with stirring at a temperature of 10 to 60 ^° C., preferably from 20 to 50, particularly preferably from 20 to 40 ^° C.

Under these reaction conditions, it is allowed to react for 30 minutes to 48 hours, preferably 45 minutes to 36 hours, more preferably 1 to 24 hours.

The compound (S) is added in amounts of from 0.1 to 40% by weight, preferably from 0.5 to 30% by weight and more preferably from 1 to 20% by weight, based on the SiO 2 content.

For example, to determine the optimum amount of compound (S) per surface of (K), proceed as follows:

First, in a systematic series, samples of (K) are reacted with such amounts of (S) that, for example, 20, 40, 60, 80 and 100% of the hydroxy groups are attached of the surface of (K) can be modified with (S). Of course, other amounts and greater or lesser intervals between the amounts in the modification of (K) are possible.

From these samples the viscosity is determined and plotted against the amount of (S). Usually, one will find a range in which the viscosity changes only slightly depending on the amount of (S) and a range in which the viscosity changes greatly depending on the amount of (S). Ideally, two branches, correspondingly elongated as a straight line, form an intersection, optionally in a range of ± 10%, preferably in the range of ± 5%, of the optimum amount of (S) per surface of (K) with respect to indicates the viscosity.

After addition of water and solvent (L) and the subsequent reaction with the silane, the silica sol (K) is generally present as a 3 to 30% strength by weight colloidal solution, the ratio of water to solvent (L) in the Rule 10:90 to 90:10 (v / v), preferably 25:75 to 75:25, and more preferably 40:60 to 60:40.

The organic coating composition is introduced into this solution or, if one component of the coating composition is reactive with respect to water and / or the solvent (L) used, the component of the coating composition which is not significantly reactive under the mixing conditions.

The coating compositions are in principle not limited. Advantageously, they have a viscosity at 25 ° C of not more than 4000 mPas (according to DIN EN ISO 3219 in a cone-plate rotation viscometer at a shear rate of 100 S " ¹ ), preferably not more than 3000 mPas, more preferably not more than 2000 mPas, more preferably not more than 1500 and in particular not more than 1000 mPas.

The condition is that the coating composition should have a boiling point above the boiling point of the solvent under the conditions of distillation, preferably at least 10 ⁰ C higher, more preferably at least 25 ⁰ C and most preferably at least 40 ⁰ C higher.

If the coating composition is a free-radically polymerizable one, it may be a preferred embodiment of the present invention to add to the coating composition at least one inhibitor against free radical polymerization.

These may be phenols, quinones, hydroquinones, N-oxyls, aromatic amines, especially phenylenediamines, sulfonamides, oximes, hydroxylamines, urea derivatives, phosphorus-containing compounds, sulfur-containing compounds or metal salts act.

Such inhibitors are described, for example, in DE 10258329 A1, paragraphs [0012] to [0043] and [0051] to [0071], especially [0051] to [0054] and [0069] to [0071], which are hereby incorporated by reference present disclosure.

Preferred are N-oxyls, e.g. 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6, 6-tetramethyl-piperidine-N-oxyl, 2,2,6,6-tetramethyl-piperidine-N-oxyl, 4,4 ', 4 "-tris (2,2,6,6-tetramethyl-piperidine-N- oxyl) phosphite or 3-oxo-2,2,5,5-tetra-methyl-pyrrolidine-N-oxyl, phenols and naphthols, for example p-aminophenol, p-nitrosophenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-methyl-2,6-tert-butylphenol (2,6-tert-butyl -p-cresol) or 4-tert-butyl-2,6-dimethylphenol, quinones, such as hydroquinone or hydroquinone monomethyl ether, aromatic amines, such as N, N-diphenylamine, N-nitroso-diphenylamine, phenylenediamines, such as N, N'-dialkyl-para-phenylenediamine, wherein the alkyl radicals may be identical or different and each independently of one another consist of 1 to 4 carbon atoms and may be straight-chain or branched, hydroxylamines, such as N, N-diethylhydroxylamine, urea derivatives, such as e.g. Urea or thiourea, phosphorus-containing compounds, e.g. Hypophosphorous acid, Irgaphos® 168 from Ciba Spezialitätenchemie, PPQ, triphenylphosphine, triphenyl phosphite or triethyl phosphite or sulfur-containing compounds, such as e.g. Diphenyl sulfide or phenothiazine and mixtures thereof.

Particular preference is given to phenols, hydroquinones, N-oxyls, phenothiazine, phosphorus-containing compounds and mixtures thereof.

Very particular preference is given to hydroquinone monomethyl ether, phenothiazine, 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl, tetramethylpiperidine N-oxyl, phenothiazine, triphenyl phosphite and mixtures thereof.

Preferred combinations are hydroquinone monomethyl ether and triphenyl phosphite as well as hydroquinone monomethyl ether and phenothiazine.

The inhibitors are usually added in amounts of 1 to 1000 ppm, preferably 5 to 800, particularly preferably 10 to 500 and very particularly preferably 20 to 300 ppm.

Preferably, the added inhibitors are aerobic inhibitors that require the presence of molecular oxygen (O 2) to be fully effective. It may represent a particularly preferred embodiment, as inhibitors Use combination of at least one aerobic and at least one anaerobic inhibitor.

Aerobic inhibitors act only in the presence of oxygen, such aerobic inhibitors are, for example, phenolic polymerization inhibitors, such as hydroquinone monomethyl ether.

This has the advantage that the inhibitors can develop their free-radical inhibiting effect during distillation in the presence of an oxygen-containing gas.

As the oxygen-containing gas, air or a mixture of air and a gas inert under the reaction conditions may be preferably used. Nitrogen, helium, argon, carbon monoxide, carbon dioxide, water vapor, lower hydrocarbons or mixtures thereof can be used as the inert gas. The oxygen content of the oxygen-containing gas may be, for example, up to 21% by volume, preferably 1 to 21, particularly preferably 5 to 21 and very particularly preferably 10 to 20% by volume. Of course, if desired, higher oxygen contents can also be used, for example up to 50% by volume. Preferably, the coating composition is coated during mixing with the silicate with an oxygen-containing gas and / or passed through the mixture. During the distillation, an oxygen-containing gas is preferably also bubbled through the distillation template, for example by a dip or a frit, and / or used as a stripping gas.

In contrast, if the finished coating composition is to be cured by free radicals, for example by activation of photoinitiators (see below), it is advantageous to carry out the desired curing under an inert atmosphere in which the content of molecular oxygen is reduced.

On the other hand, anaerobic polymerization inhibitors, e.g. Phenothiazine, do not require oxygen, but are consumed by oxygen in non-polymerization-inhibiting side reactions.

It may be advantageous to work with the exclusion of light when dealing with the free-radically polymerizable compounds in order to reduce the risk of premature polymerization of the radiation-curable compounds. This can be done by working in opaque equipment or, when working in glass parts, by using brown glass or covering the glass parts.

Distillation of water and the organic solvent (L) is carried out under normal or reduced pressure, preferably at 10 hPa to normal pressure, especially preferably at 20 hPa to normal pressure, most preferably at 50 hPa to normal pressure and in particular at 100 hPa to normal pressure.

The temperature at which the distillation takes place depends on the boiling point of water and / or organic solvent (L) at the respective pressure.

Preferably, the distillation conditions are chosen so that water and the organic solvent form an azeotrope under the conditions.

The temperature is preferably not more than 80 ^° C., preferably not more than 70 ^° C.

The distillation can be carried out batchwise, semicontinuously or continuously.

For example, it can be carried out batchwise from a stirred tank, which may optionally be placed a short rectification column.

The heat supply to the stirred tank via internal and / or external heat exchanger conventional design and / or double wall heater, preferably external circulation evaporator with natural or forced circulation. The mixing of the reaction mixture is carried out in a known manner, for. B. by stirring, pumping or natural circulation.

Continuously, the distillation is preferably carried out by passing the distillation charge over a falling-film evaporator or a heat exchanger.

Suitable distillation apparatuses for this purpose are all distillation apparatuses known to the person skilled in the art, e.g. Circulation evaporator, thin film evaporator, falling film evaporator, wiper blade evaporator, optionally with each attached rectification columns and stripping columns. Suitable heat exchangers are, for example, Robert evaporators or tube or plate heat exchangers.

As a rule, water and solvent (L) are distilled off to the extent that the content of silicates in the coating composition is from 5 to 80% by weight, preferably from 20 to 60 and particularly preferably from 20 to 50% by weight.

The residual content of water in the finished product should be less than 5% by weight, preferably less than 3, particularly preferably less than 2, very particularly preferably less than 1, in particular less than 0.5 and especially less than 0.3% by weight. The residual content of solvent (L) in the finished product should be less than 15% by weight, preferably less than 10, particularly preferably less than 5, very particularly preferably less than 3, in particular less than 2 and especially less than 1% by weight.

In a preferred embodiment of the present invention, the reaction mixture remains from the addition of the organic solvent (L) until the end of the distillation, i. until reaching the above-mentioned desired residual water content in the finished product, in the acidic range, i. the pH is less than 7, preferably less than 6, more preferably less than 5 and most preferably less than 4. Since the pH can only be determined uncertainly with decreasing water content, the addition of basic compounds in the reaction mixture is omitted at the end of the distillation.

Basic compounds in this sense are those which upon addition of the same amount of the basic compound in an amount of water corresponding to the volume of the reaction mixture are capable of raising the pH from pH 7 to at least pH 8 or above. In particular, this includes hydroxides, carbonates, bicarbonates, basic oxides, primary, secondary or tertiary amines or ammonia.

The removal of the water can be carried out instead of the distillation by absorption, pervaporation or diffusion through membranes.

The coating compositions are those binder-crosslinker combinations which are customarily used for use in paints, preferably one- or two-component polyurethane coatings, epoxy resins, melamine-formaldehyde resins or radiation-curable compounds, more preferably one- or two-component ones Polyurethane coatings or radiation-curable compounds, and most preferably radiation-curable compounds.

Epoxy resins are those which are mostly composed of a carboxylic acid component and an epoxy component.

The carboxylic acid component is usually composed of dicarboxylic acid and optionally polycarboxylic acids.

The dicarboxylic acids include, for example, aliphatic dicarboxylic acids such as oleic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, cork acid, azelaic acid, sebacic acid, undecane-α, ω-dicarboxylic acid, dodecane-α, ω-dicarboxylic acid, cis- and trans-cyclohexane-1,2-dicarboxylic acid, cis- and trans-cyclohexane-1,3-dicarboxylic acid, cis- and trans-cyclohexane-1,4-dicarboxylic acid, cis- and trans- Cyclopentane-1,2-dicarboxylic acid, cis- and trans-cyclopentane-1-dicarboxylic acid. Furthermore, it is also possible to use aromatic dicarboxylic acids, such as, for example, phthalic acid, isophthalic acid or terephthalic acid. It is also possible to use unsaturated dicarboxylic acids, such as maleic acid or fumaric acid.

The dicarboxylic acids mentioned can also be substituted by one or more radicals selected from C 1 -C 10 -alkyl groups, C 3 -C 12 -cycloalkyl groups or C 1 -C -aryl groups.

Particular preference is given to using malonic acid, succinic acid, glutaric acid, adipic acid, 1, 2, 1, 3 or 1, 4-cyclohexanedicarboxylic acid (hexahydrophthalic acids), phthalic acid, isophthalic acid, terephthalic acid or their mono- or dialkyl esters.

Polycarboxylic acids are, for example, aconitic acid, 1,3,5-cyclohexanetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1, 2,4,5-

Benzoltetracarboxylic acid (pyromellitic acid) and mellitic acid and low molecular weight polyacrylic acids.

Examples of epoxy compounds are glycidyl ethers of aliphatic or aromatic polyols. Such products are commercially available in large numbers.

Aromatic glycidyl ethers are e.g. Bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol B diglycidyl ether, bisphenol S diglycidyl ether, hydroquinone diglycidyl ether, alkylation products of phenol / dicyclopentadiene, e.g. 2,5-bis [(2,3-E-epoxypropoxy) phenyl] octahydro-4,7-methano-5H-indene (CAS No. [13446-85-0]), tris [4- (2, 3-epoxypropoxy) phenyl] methane isomers) CAS-No. [66072-39-7]), phenol based epoxy novolacs (CAS # [9003-35-4]) and cresol based epoxy novolacs (CAS # [37382-79-9]).

Aliphatic glycidyl ethers are, for example, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,1,2,2-tetrakis [4- (2,3-epoxypropoxy) phenyl] ethane (CAS No. [ 27043-37-4]), diglycidyl ethers of polypropylene glycol (α, ω-bis (2,3-epoxypropoxy) poly (oxypropylene) (CAS No. [16096-30-3]) and hydrogenated bisphenol A (2 , 2-bis [4- (2,3-epoxypropoxy) cyclohexyl] propane, CAS No. [13410-58-7]).

Particular preference is given to bisphenol A, F or B type polyglycidyl compounds whose completely hydrogenated derivatives and glycidyl ethers of polyhydric alcohols, for example of 1,4-butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, 1,6-hexanediol, of glycerol, trimethylolpropane and pentaerythritol. Examples of such polyepoxide compounds are Epikote ^® 1001, Epikote ^® 1007, and Epikote ^® 162 (epoxide value: about 0.61 mol / 100 g) from Resolution, Rutapox® 0162 (epoxide value: about 0.58 mol / 100g) Hexion, Araldite ^® DY 0397 (epoxide value: about 0.83 mol / 100g) and Araldit®GT 6063 (0.14 mol / 100 g) Huntsman (formerly Vantico AG).

Very particular preference is given to bisphenol A diglycidyl ether, 1,4-butanediol diglycidyl ether, trimethylolpropane triglycidyl ether and pentaerythritol tetraglycidyl ether, in particular bisphenol A diglycidyl ether.

The epoxy compound preferably has an epoxide number of 0.1 to 10 equivalents / kg, preferably 0.5 to 8, very particularly preferably 1 to 7 equivalents / kg.

The epoxy compound and the component having epoxy groups reactive groups are usually in a molar ratio of 0.5: 1 to 2: 1, preferably 0.7: 1 to 1, 5: 1 and more preferably 0.9: 1 to 1, 1: 1 mixed and optionally reacted with catalysis at elevated temperature.

However, it is also possible to cure epoxy resins without carboxylic acids, e.g. with amines, anhydrides, melamine, phenolic resins or with UV starters. Such systems are known to the person skilled in the art.

For example, melamine-formaldehyde resins may be

1. fully to highly methylolated and fully alkylated to highly alkylated resins

(H M MM types)

2.1 partially methylolated and highly alkylated resins (high imino types) 2.2. partially methylolated and partially alkylated resins (methylol types)

3. low methylolated resins (melamine-formaldehyde condensates)

The first large group of fully etherified melamine-formaldehyde resins in which the so-called Einbaumolverhältnis melamine: formaldehyde: alcohol theoretically 1: 6: 6, in practice usually 1:> 5.5:> 5.0 and usually 1 :> 5.5:> 4.5, are characterized by a very good high solids behavior (relatively low viscosity at high solids content). In this crosslinker group, the free formaldehyde can be easily reduced due to the low viscosity of the amino resin. Currently attainable is a content of free formaldehyde <0.3% by weight, with specially prepared amino resins also <0.1% by weight. The commercial products contain mostly methanol as alcohol, but mixed etherified or fully butylated types are also known.

The low thermal reactivity at baking conditions, such as 140 ^° C. for 20 minutes, requires strong acid catalysis for these fully etherified melamine-formaldehyde resins. This gives a very rapid curing, by re-etherification with the binder to release the etherification alcohols a ho mogenes Conetzwerk. With this catalysis with strong acids very short curing times, as in partially methylolated melamine-formaldehyde resins are possible. During the crosslinking a formaldehyde emission is possible, which is significantly higher than the free formaldehyde and is due to the cleavage of methylol groups.

The second large group of partially etherified melamine-formaldehyde resins, which in practice usually has a built-in molar ratio of melamine: formaldehyde: alcohol of 1: 3 to

5.4: 2 to 4.3, is characterized by a significantly increased compared to the first group thermal reactivity without acid catalysis. During the production of these crosslinkers, a self-condensation takes place, which leads to a higher viscosity (lower high-solids behavior) and thus makes the removal of free formaldehyde during distillation more difficult. For these products, a content of free formaldehyde of 0.5 to 1, 5% standard, but there are also products with a content of free formaldehyde from 0.3 to 3% by weight. Here, too, methylated, butylated and mixed etherified types are widely used as commercial products. The etherification with further alkylating agents is described in the literature or corresponding special products are commercially available.

High-imino and methylol types as respective subgroups both exhibit incomplete methylolation, i. Formaldehyde Einbaumolverhältnisse of less than 1:

5.5. However, the high-imino types are distinguished from the methylol types by a high degree of alkylation, i. the proportion of etherified methylol groups on the incorporated formaldehyde equivalents, of usually up to 80%, whereas, on the other hand, the methylol types generally have <70%.

Fields of application for the partially methylolated melamine-formaldehyde resins extend over all fields of application, also in combination with HMMM types for reactivity adjustment, where curing temperatures of 100 to 150 ^° C. are required. Additional catalysis using weak acids is possible and common practice.

In addition to the reaction of the amino resin with the binder, a significantly increased proportion of intrinsic crosslinking of the crosslinker takes place with itself. The result is a reduced elasticity of the overall system, which must be compensated by the appropriate selection of the combination partner. In contrast, the reduced total formaldehyde emission from the coatings produced therefrom is advantageous.

Typical melamine-formaldehyde resins have a solids content of at least 50% by weight, preferably at least 85, particularly preferably at least 90, very preferably at least 92 and in particular at least 95% by weight.

The solids content is determined in accordance with ISO 3251, by spreading 2 g of the sample material and 2 ml of n-butanol in a well-ventilated drying oven for a period of 2 hours to 125 ⁰ C are heated. The sample is weighed before and after, and the ratio indicates the solids content.

The content of free formaldehyde is for example not more than 1% by weight, preferably not more than 0.8% by weight, more preferably not more than 0.5% by weight and very particularly preferably not more than 0.4% by weight.

In a particularly preferred embodiment, the content of free formaldehyde is preferably not more than 0.2% by weight, more preferably not more than 0.15% by weight and most preferably not more than 0.1% by weight.

The content of free formaldehyde is determined according to EN ISO 9020.

The acid number of preferred melamine-formaldehyde resins is less than 3, more preferably less than 1 mg KOH / g, determined according to ISO 3682.

Depending on the melamine-formaldehyde resin used, catalysis with strong or weak acids may be useful.

For the purposes of this document, weak acids are understood to mean monovalent or polyvalent, organic or inorganic, preferably organic acids having a pKa of between 1.6 and 5.2, preferably between 1.6 and 3.8.

Examples thereof are carbonic acid, phosphoric acid, formic acid, acetic acid and maleic acid, glyoxylic acid, bromoacetic acid, chloroacetic acid, thioglycolic acid, glycine, cyanoacetic acid, acrylic acid, malonic acid, hydroxypropanedioic acid, propionic acid, lactic acid, 3-hydroxypropionic acid, glyceric acid, alanine, sarcosine, fumaric acid, acetoacetic acid, succinic acid , isobutyrate, pentanoic acid, ascorbic acid, citric acid, nitrilotriacetic acid, cyclopentanecarboxylic acid, 3-methylglutaric acid, adipic acid, hexanoic acid, benzoic acid, cyclohexanecarboxylic acid, heptanedioic acid, heptanoic acid, phthalic acid, isophthalic acid, terephthalic acid, toluic acid, phenylacetic acid, phenoxyacetic acid, mandelic acid or sebacic acid ,

Preference is given to organic acids, preferably mono- or polybasic carboxylic acids. Particularly preferred are formic acid, acetic acid, maleic acid or fumaric acid.

In the context of this document, strong acids are understood as meaning monovalent or polyvalent, organic or inorganic, preferably organic acids having a pKa of less than 1.6, and more preferably less than 1. Examples thereof are sulfonic acids, sulfuric acid, pyrophosphoric acid, sulfurous acid and tetrafluoroboric acid, trichloroacetic acid, dichloroacetic acid, oxalic acid, nitroacetic acid.

It is likewise possible to use blocked acids, in particular blocked sulfonic acid derivatives.

Such acids are known to the skilled person as such, and are described e.g. marketed in free and blocked form under the tradename Nacure®.

For polyurethane coatings, in principle, an isocyanate group-containing compound, often referred to as a crosslinker, is reacted with a compound having isocyanate-reactive groups, usually hydroxy groups. The latter compound is also referred to as a binder.

In one-component polyurethane coatings, the isocyanate groups of the isocyanate component are blocked, i. reacted reversibly with a compound which is released under the conditions of curing (stoving) and then allows a reaction of the thus liberated isocyanate groups with the binder.

In two-component polyurethane coatings, on the other hand, crosslinkers and binders are mixed together just before application and then reacted with one another in the course of curing.

In the latter case, it makes sense according to the invention to incorporate the silicates into the binder component, since the isocyanate component usually reacts at least with water, but often also with the organic solvent (L).

As isocyanate component are known in the art polyisocyanates based on diisocyanates, in particular based on 1, 6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (1-isocyanato-3,3,5-trimethyl-5- (isocyanatomethyl) cyclohexane, IPDI) or 4,4'-di (isocyanatocyclohexyl) methane (H12MDI), especially based on HDI and / or IPDI.

The isocyanate component generally has a content of NCO groups (or blocked NCO groups) calculated as NCO with a molecular weight of 42 g / mol up to 30% by weight, preferably up to 25% by weight.

The polyisocyanate may contain, for example, isocyanurate groups, uretdione groups, biuret groups, oxadiazinetrione groups, iminooxadiazinedione groups, urethane groups and / or allophanate groups and may be, for example, uretonimine-modified, carbodiimide-modified or hyperbranched. The binders may be, for example, polyacrylate polyols, polyester polyols, polyether polyols, polyurethane polyols; polyurea; Polyester polyacrylate latpolyols; polyester polyurethane polyols; Polyurethane polyacrylate polyols, polyurethane-modified alkyd resins; Fatty acid-modified polyester polyurethane polyols, copolymers with allyl ethers, graft polymers from the mentioned substance groups with, for example, different glass transition temperatures, and mixtures of said binders. Preference is given to polyacrylate polyols, polyester polyols and polyether polyols.

Preferred OH numbers, measured according to DIN 53240-2, are 40-350 mg KOH / g solid resin for polyester, preferably 80-180 mg KOH / g solid resin, and 15-250 mg KOH / g solid resin for polyacrylatols, preferably 80-160 mg KOH / g.

In addition, the binders may have an acid number according to DIN EN ISO 3682 up to 200 mg KOH / g, preferably up to 150 and particularly preferably up to 100 mg KOH / g.

Polyacrylate polyols preferably have a molecular weight M _n of at least 1000, particularly preferably at least 2000 and very particularly preferably at least 5000 g / mol. The molecular weight M _n may be, for example, up to 200,000, preferably up to 100,000, particularly preferably up to 80,000 and very particularly preferably up to 50,000 g / mol.

The polyacrylate polyols are copolymers of at least one (meth) acrylic ester with at least one compound having at least one, preferably exactly one hydroxyl group and at least one, preferably exactly one (meth) acrylate group.

Other polymers are e.g. Polyesterols, as are obtainable by condensation of polycarboxylic acids, in particular dicarboxylic acids with polyols, in particular diols. In order to ensure a functionality of the polyester polyol which is suitable for the polymerization, triols, tetrols, etc., as well as triacids, etc., are also used in part.

Polyesterpolyols are known, for example, from Ullmanns Encyklopadie der technischen Chemie, 4th Edition, Volume 19, pages 62 to 65. Preference is given to using polyesterpolyols which are obtained by reacting dihydric alcohols with dibasic carboxylic acids. Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof to prepare the polyesterpolyols. The polycarboxylic acids may be aliphatic, cycloaliphatic, aralipha be table, aromatic or heterocyclic and optionally substituted, for example by halogen atoms, substituted and / or unsaturated.

Also suitable as polymers are polyetherols which are prepared by addition of ethylene oxide, propylene oxide or butylene oxide to H-active components. Likewise, polycondensates of butanediol are suitable.

However, radiation-curable compounds are preferably used as coating compositions.

Suitable radiation-curable compounds are those which have at least one free-radically polymerizable group. These may be those with one and / or those having more than one ethylenically unsaturated group.

Preferably, compounds having multiple, i. at least two, co-polymerisable, ethylenically unsaturated groups around vinyl ether or (meth) acrylate compounds, particularly preferably the acrylate compounds, i. the derivatives of acrylic acid.

Preferred vinyl ether and (meth) acrylate compounds contain 2 to 20, preferably 2 to 10 and most preferably 2 to 6 copolymerizable, ethylenically unsaturated double bonds.

Particular preference is given to those compounds having a content of ethylenically unsaturated double bonds of 0.1 to 0.7 mol / 100 g, very particularly preferably 0.2 to 0.6 mol / 100 g.

Unless stated otherwise, the number average molecular weight M _{n of} the compounds is preferably below 15,000, more preferably 300-12,000, most preferably 400-5,000 and in particular 500-3,000 g / mol (determined by gel permeation chromatography with polystyrene as standard and Tetrahydrofuran as eluent).

As (meth) acrylate compounds may be mentioned (meth) acrylic acid esters and in particular acrylic acid esters and vinyl ethers of polyfunctional alcohols, in particular those which contain no further functional groups or at most ether groups in addition to the hydroxyl groups. Examples of such alcohols are, for example, bifunctional alcohols, such as ethylene glycol, propylene glycol and their more highly condensed representatives, for example diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, etc., 1, 2, 1, 3 or 1, 4-butanediol, 1, 5 Pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentylglycol, alkoxylated phenolic compounds, such as ethoxylated and / or propoxylated bisphenols, 1, 2-, 1, 3- or 1, 4- Cyclohexanedimethanol, trifunctional and higher herfunktionelle alcohols, such as glycerol, trimethylolpropane, butanetriol, trimethylolethane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, sorbitol, mannitol and the corresponding alkoxylated, in particular ethoxylated and / or propoxylated alcohols.

The alkoxylation products are obtainable in a known manner by reacting the above alcohols with alkylene oxides, in particular ethylene oxide or propylene oxide. Preferably, the degree of alkoxylation per hydroxyl group is 0 to 10, i. 1 mol of hydroxyl group can be alkoxylated with up to 10 mol of alkylene oxides.

Other suitable (meth) acrylate compounds are polyester (meth) acrylates, which are the (meth) acrylic esters or vinyl ethers of polyesterols, and urethane, epoxide or melamine (meth) acrylates.

Urethane (meth) acrylates are e.g. obtainable by reacting polyisocyanates with hydroxyalkyl (meth) acrylates and optionally chain extenders such as diols, polyols, diamines, polyamines or dithiols or polythiols.

The urethane (meth) acrylates preferably have a number average molecular weight M _{n of} from 500 to 20,000, in particular from 750 to 10,000, particularly preferably from 750 to 3,000 g / mol (determined by gel permeation chromatography using polystyrene as standard).

The urethane (meth) acrylates preferably have a content of from 1 to 5, more preferably from 2 to 4 moles of (meth) acrylic groups per 1,000 g of urethane (meth) acrylate.

Epoxide (meth) acrylates are obtainable by reacting epoxides with (meth) acrylic acid. Suitable epoxides are, for example, epoxidized olefins or glycidyl ethers, e.g. Bisphenol A diglycidyl ethers or aliphatic glycidyl ethers such as butanediol diglycidyl ether.

Melamine (meth) acrylates are obtainable by reacting melamine with (meth) acrylic acid or its esters.

The epoxide (meth) acrylates and melamine (meth) acrylates preferably have a number average molecular weight M _n of 500 to 20,000, particularly preferably from 750 to 10,000 g / mol and very particularly preferably from 750 to 3,000 g / mol; the content of (meth) acrylic groups is preferably 1 to 5, particularly preferably 2 to 4 per 1000 g of epoxy (meth) acrylate or melamine (meth) acrylate (determined by gel permeation chromatography with polystyrene as standard and tetrahydrofuran as eluent). Also suitable are carbonate (meth) acrylates which contain on average preferably 1 to 5, in particular 2 to 4, particularly preferably 2 to 3 (meth) acrylic groups and very particularly preferably 2 (meth) acrylic groups.

The number average molecular weight M _{n of} the carbonate (meth) acrylates is preferably less than 3,000 g / mol, more preferably less than 1,500 g / mol, more preferably less than 800 g / mol (determined by gel permeation chromatography with polystyrene as standard, solvent tetrahydrofuran).

The carbonate (meth) acrylates are readily obtainable by transesterification of carbonic acid esters with polyhydric, preferably dihydric alcohols (diols, eg hexanediol) and subsequent esterification of the free OH groups with (meth) acrylic acid or transesterification with (meth) acrylic esters, as it eg in EP-A 92,269. They are also available by reacting phosgene, urea derivatives with polyvalent, e.g. dihydric alcohols.

The radiation-curable, free-radically or cationically polymerizable compounds having only one ethylenically unsaturated, copolymerizable group are often reactive diluents, that is to say compounds of low viscosity which simultaneously participate in the polymerization reaction.

Called e.g. C 1 -C 20 -alkyl (meth) acrylates, vinylaromatics having up to 20 carbon atoms, vinyl esters of carboxylic acids containing up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl ethers of alcohols containing from 1 to 10 carbon atoms, α, β-unsaturated Carboxylic acids and their anhydrides and aliphatic hydrocarbons having 2 to 8 carbon atoms and 1 or 2 double bonds.

Preferred (meth) acrylic acid alkyl esters are those having a C 1 -C 10 -alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.

In particular, mixtures of (meth) acrylic acid alkyl esters are also suitable.

Vinyl esters of carboxylic acids having 1 to 20 carbon atoms are e.g. Vinyl laurate, vinyl stearate, vinyl propionate and vinyl acetate.

α, β-Unsaturated carboxylic acids and their anhydrides can be, for example, acrylic acid, methacrylic acid, fumaric acid, crotonic acid, itaconic acid, maleic acid or maleic anhydride, preferably acrylic acid.

Suitable vinylaromatic compounds are, for example, vinyltoluene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene. Examples of nitriles are acrylonitrile and methacrylonitrile.

Suitable vinyl ethers are e.g. Vinyl methyl ether, vinyl isobutyl ether, vinyl hexyl ether and vinyl octyl ether.

As non-aromatic hydrocarbons having 2 to 8 carbon atoms and one or two olefinic double bonds may be mentioned butadiene, isoprene, and ethylene, propylene and isobutylene.

Furthermore, N-vinylformamide, N-vinylpyrrolidone and N-vinylcaprolactam can be used.

Furthermore, the silicate-containing coating composition obtained according to the invention can still be mixed with photoinitiators. Less preferably, the photoinitiators may already be present during mixing with the silicates. Therein, photoinitiators known to those skilled in the art may be used, e.g. those in "Advances in Polymer Science", Volume 14, Springer Berlin 1974 or in K.K. Dietliker, Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints, Volume 3; Photoinitiators for Free Radical and Cationic Polymerization, P.K.T. Oldring (Eds), SITA Technology Ltd, London.

Suitable examples include mono- or Bisacylphosphinoxide Irgacure® 819 (bis (2,4,6-tri-methylbenzoyl) phenylphosphine oxide), as described for example in EP-A 7 508, EP-A 57 474, DE-A 196 18 720, EP-A 495 751 are described or EP-A 615 980, for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin ^® TPO), ethyl-2,4,6-trimethylben- zoylphenylphosphinat, benzophenones, hydroxyacetophenones, phenylglyoxylic acid and its derivatives or mixtures these photoinitiators. Examples which may be mentioned are benzophenone, acetophenone, acetonaphthoquinone, methyl ethyl ketone, valerophenone, hexanophenone, α-phenylbutyrophenone, p-morpholinopropiophenone, dibenzosuberone, 4-morpholinobenzophenone, 4-morpholinodeoxybenzoin, p-diacetylbenzene, 4-aminobenzophenone, 4 ' -Methoxyacetophenone, β-methylanthraquinone, tert-butylanthraquinone, anthraquinone-carboxylic acid ester, benzaldehyde, α-tetralone, 9-acetylphenanthrene, 2-acetylphenanthrene, 10-thioxanthenone, 3-acetylphenanthrene, 3-acetylindole, 9-fluororon, 1-indanone, 1 , 3,4-triacetylbenzene, thioxanthen-9-one, xanthen-9-one, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropyltrioxanthone, 2,4-dichlorothioxanthone , Benzoin, benzoin isobutyl ether, chloroxanthenone, benzoin tetrahydropyranyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoin isopropyl ether, 7-H-benzoin methyl ether, benz [de] anthracene-7 -one, 1-naphthaldehyde, 4,4'-bis (dimethylamino) benzophenone, 4-phenylbenzophenone, 4-chlorobenzene zophenone, Michler's ketone, 1-acetonaphthone, 2-acetonaphthone, 1-benzoylcyclohexan-1-ol, 2-hydroxy-2,2-dimethylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-Diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxyacetophenone, acetophenone dimethyl ketal, o-methoxybenzophenone, triphenylphosphine, tri-o-tolylphosphine, benz [a] anthracene-7,12-dione, 2, 2-diethoxyacetophenone, benzil ketals such as benzil dimethyl ketal, 2-methyl-1 - [4- (methylthio) phenyl] -2-morpholinopropan-1-one, anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthra- quinone, 1-chloroanthraquinone, 2-amylanthraquinone and 2,3-butanedione.

Also suitable are non-yellowing or slightly yellowing photoinitiators of the phenylglyoxalic acid ester type, as described in DE-A 198 26 712, DE-A 199 13 353 or WO 98/33761.

Among the photoinitiators mentioned, phosphine oxides, α-hydroxyketones and benzophenones are preferred.

In particular, mixtures of different photoinitiators can be used.

The photoinitiators may be used alone or in combination with a photopolymerization onspromotor, e.g. benzoic, amine or similar type.

In addition to the photoinitiators, further typical coatings additives can be added, for example antioxidants, oxidation inhibitors, stabilizers, activators (accelerators), fillers, pigments, dyes, degassing agents, brighteners, antistatic agents, flame retardants, thickeners, thixotropic agents, flow aids, binders, Defoamers, fragrances, surface active agents, viscosity modifiers, plasticizers, plasticizers, tackifying resins (tackifiers), chelating agents or compatibilizers.

As a post-curing accelerator, e.g. Tin octoate, zinc octoate, dibutyltin laureate or diaza [2.2.2] bicyclooctane.

It is furthermore possible to add one or more photochemically and / or thermally activatable initiators, for example potassium peroxodisulfate, dibenzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide, azobisisobutyronitrile, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, tert-butyl peroctoate or benzopinacol, as well as, for example, those thermally activatable initiators having a half life of 80 ⁰ C of more than 100 hours, such as di-t-butyl peroxide, cumene hydroperoxide, dicumyl peroxide, t-butyl perbenzoate, silylated pinacols, the z. B. commercially available under the trade name ADDID 600 from Wacker or hydroxyl-containing amine-N-oxides, such as 2,2,6,6-tetramethylpiperidine-N-oxyl, 4-hydroxy-2,2,6, 6-tetramethylpiperidine-N-oxyl etc. Further examples of suitable initiators are described in "Polymer Handbook" 2nd ed., Wiley & Sons, New York.

Suitable thickeners besides free-radically (co) polymerized (co) polymers, customary organic and inorganic thickeners such as hydroxymethylcellulose or bentonites are also suitable.

As chelating agents, e.g. Ethylenediamine and their salts and ß-diketones are used.

Suitable fillers include silicates, e.g. For example, by hydrolysis of silicon tetrachloride available silicates such as Aerosil ^® the Fa. Degussa, silica, talc, aluminum silicates, magnesium silicates, calcium carbonates etc. Since silicates are evenly introduced by the inventive method in a coating composition, it represents a preferred embodiment, no further fillers admit.

Suitable stabilizers include typical UV absorbers such as oxanilides, triazines and benzotriazole (the latter available as Tinuvin ^® grades from Ciba-Spezialitatenchemie) and benzophenones. These may be used alone or together with suitable radical scavengers, for example sterically hindered amines such as 2,2,6,6-tetramethylpiperidine, 2,6-di-tert-butylpiperidine or derivatives thereof, eg. For example, bis (2,2,6,6-tetra-methyl-4-piperidyl) sebacinate can be used. Stabilizers are usually used in amounts of 0.1 to 5.0 wt .-%, based on the solid components contained in the preparation.

The silicate-containing coating compositions and coating formulations obtained according to the invention are particularly suitable for coating substrates such as wood, paper, textile, leather, fleece, plastic surfaces, glass, ceramics, mineral building materials such as cement blocks and fiber cement boards, or metals or coated metals, preferably plastics or metals, which may be present as films, for example.

The thickness of such a layer to be cured as described may be from 0.1 μm to several mm, preferably from 1 to 2000 μm, more preferably 5 to 1000 μm, most preferably from 10 to 500 μm and in particular from 10 to 250 μm.

Furthermore, substrates coated with a multilayer coating according to the invention are also the subject of the present invention.

The substrates are coated by customary methods known to the person skilled in the art, at least one coating composition being applied to the substrate to be coated Apply substrate in the desired strength and the optional volatile constituents of the coating composition, optionally with heating removed. This process can optionally be repeated one or more times. The application to the substrate can in a known manner, for. Example by spraying, filling, doctoring, brushing, rolling, rolling, casting, lamination, injection molding or coextrusion done. The coating thickness is usually in a range of about 3 to 1,000 g / m ² and preferably 10 to 200 g / m ² .

Furthermore, a method for coating substrates is disclosed, in which the coating composition is applied to the substrate and optionally dried, cured with electron beams or UV exposure under an oxygen-containing atmosphere or preferably under inert gas, optionally at temperatures up to the height of the drying temperature and then at temperatures up to to 160 ⁰ C, preferably between 60 and 160 ⁰ C, thermally treated.

The method for coating substrates can also be carried out so that after application of the coating composition initially at temperatures up to 160 ⁰ C, preferably between 60 and 160 ° C, thermally treated and then with electron beams or UV exposure under oxygen or preferably under inert gas is hardened.

The curing of the films formed on the substrate can optionally be carried out exclusively thermally. In general, however, the coatings are cured both by irradiation with high-energy radiation and thermally.

The curing can also take place in addition to or instead of the thermal curing by NIR radiation, wherein NIR radiation here electromagnetic radiation in the wavelength range of 760 nm to 2.5 microns, preferably from 900 to 1500 nm is designated.

Optionally, if several layers of the coating composition are applied to one another, thermal, NIR and / or radiation curing can take place after each coating operation.

Suitable radiation sources for radiation curing are, for example, low-pressure mercury lamps, medium-pressure lamps with high-pressure lamps and fluorescent tubes, pulse emitters, metal halide lamps, electronic flash devices, whereby a radiation curing without photoinitiator is possible, or Excimerstrahler. The radiation is cured by exposure to high-energy radiation, ie UV radiation or daylight, preferably light in the wavelength range of λ = 200 to 700 nm, particularly preferably from λ = 200 to 500 nm and most preferably λ = 250 to 400 nm, or by Irradiation with high-energy electrons (electron Radiation; 150 to 300 keV). The radiation sources used are, for example, high-pressure mercury vapor lamps, lasers, pulsed lamps (flash light), halogen lamps or excimer radiators. The radiation dose for UV curing, which is usually sufficient for crosslinking, is in the range from 80 to 3,000 mJ / cm ² .

Of course, several radiation sources can be used for the curing, e.g. two to four.

These can also radiate in different wavelength ranges.

The irradiation may preferably also in the absence of oxygen, for. B. under inert gas atmosphere, are performed. As inert gases are preferably nitrogen, noble gases, carbon dioxide, or combustion gases. Furthermore, the irradiation can be carried out by covering the coating mass with transparent media. Transparent media are z. As plastic films, glass or liquids, eg. B. water. Particular preference is given to irradiation in the manner described in DE-A1 199 57 900.

Another object of the invention is a method for coating substrates, wherein

i) coating a substrate with a silicate-containing coating composition as described above,

ii) removing volatile constituents of the coating composition for film formation under conditions in which the photoinitiator does not essentially form free radicals,

iii) optionally irradiating the film formed in step ii) with high energy radiation, whereby the film is precured, then optionally mechanically working the precured film coated article or contacting the surface of the precured film with another substrate,

iv) the film cures thermally or with NIR radiation

In this case, the steps iv) and iii) can also be performed in reverse order, d. H. The film may first be cured thermally or by NIR radiation and then with high energy radiation.

With the method according to the invention, it is possible to finely distribute silicate particles in organic coating compositions and to spend only a small amount of organic solvent. By the method according to the invention are Silicate particles with simple means evenly and without significant aggregation of the particles in coating materials can be introduced. In the case of the finished coating compositions, this leads to almost complete transparency in the visible range and even to increased scratch resistance. By the method according to the invention, the viscosity increase of the resulting coating compositions is less pronounced than according to comparable prior art processes.

Examples

Example 1 :

In a flask, 10 g of deionized water and 10 ml of 2-propanol were introduced. With stirring, 10 g of a basic silica sol having a SiO 2 solids content of 30% by weight and an average particle size of 9 nm (Levasil® 300, HC Stark GmbH, Leverkusen, Germany) were added to the mixture. Subsequently, so much sulfuric acid was added dropwise until a pH of 3.0 was established. 0.90 g of 3- (methacryloxy) were added to the mixture, also with stirring, propyl trimethoxysilane was added and stirred the reaction solution for 24 h at 25 ⁰ C. Subsequently, the suspension was admixed with 110 g of 2-propanol, 3 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 0.05 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatile constituents were removed while passing through a small amount of lean air (nitrogen-air mixture with about 6% by volume oxygen content) at 50 ^° C. and under reduced pressure (130 mbar). There was obtained a flowable, transparent coating composition having a SiO 2 solids content of 48%, whose water content is less than 0.5 wt .-% and which is storable for at least 3 months. The coating composition had a Brookfield viscosity of 2.08 Pa ^* s, as measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 2500 S ^-1 .

Example 2:

In a flask, 10 g of deionized water and 10 ml of 2-propanol were introduced. With stirring, 10 g of a basic silica sol having a SiO 2 solids content of 30% by weight and an average particle size of 9 nm (Levasil® 300, HC Stark GmbH, Leverkusen, Germany) were added to the mixture. Subsequently, so much sulfuric acid was added dropwise until a pH of 3.0 was established. 0.77 g of 3- (methacryloxy) were added to the mixture, also with stirring, propyl trimethoxysilane was added and stirred the reaction solution for 24 h at 25 ⁰ C. Subsequently, the suspension was admixed with 110 g of 2-propanol, 3 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 0.05 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatile constituents were passed through at 50 ^° C. and below with sparse lean air reduced pressure (130 mbar) away. This gave a flowable, transparent coating composition having a SiO 2 solids content of 48%, the water content of which was less than 0.5% by weight and which was storable for at least 3 months. The coating composition had a Brookfield viscosity of 4.64 Pa ^* s, measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 1250 S ^-1 .

Example 3:

In a beaker, 50 g of a basic silica sol having a SiC "2 solids content of 30 wt .-% and an average particle size of 13 nm (Ludox® HS 30, Grace GmbH & Co. KG, Worms, Germany) with 8 g of a strongly acidic cationic ion exchanger (Amberjet® 1200 (H), Sigma Aldrich Chemie GmbH, Taufkirchen, Germany), stirred for 30 minutes at room temperature, whereby a pH value of 2.0, and the ion exchanger was subsequently removed by filtration ,

In a flask, 20 g of the silicic acid sol acidified by means of ion exchange were mixed with 20 ml of 2-propanol. 0.83 g of 3- (methacryloxy) propyltrimethoxysilane were added to the mixture with stirring and the reaction solution for 24 h at 25 ⁰ C is stirred. Subsequently, the suspension was admixed with 132 g of 2-propanol, 6 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 0.1 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatiles were removed while passing through a small amount of lean air at 50 ⁰ C and under reduced pressure (130 mbar). A flowable, transparent coating composition having a SiC "2 solids content of 48%, which has a water content of 0.6% by weight and which is storable for at least 3 months, was obtained The coating composition had a Brookfield viscosity of 2 , 64 Pa ^* s, measured at the cone-plate viscometer at 23 ⁰ C, with a shear rate of 2500 s " ¹ .

Example 4:

In a beaker, 50 g of a basic silica sol having a SiO 2 solids content of 40 wt .-% and a mean particle size of 19 nm (Ludox® TM 40, Grace GmbH & Co. KG, Worms, Germany) with 10 g of a strongly acidic cationic ion exchanger (Amberjet® 1200 (H), Sigma Aldrich Chemie GmbH, Taufkirchen, Germany), stirred for 30 minutes at room temperature, whereby a pH value of 2.0, and the ion exchanger was subsequently removed by filtration. In a flask, 20 g of the silicic acid sol acidified by means of ion exchange were mixed with 20 ml of 2-propanol. To the mixture was added 0.49 g with stirring. (Methacryloxy) propyltrimethoxysilane was added and the reaction solution for 24 h at 25 ⁰ C stirred.

Subsequently, the suspension was admixed with 132 g of 2-propanol, 8 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 0.1 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatiles were removed while passing through a small amount of lean air at 50 ⁰ C and under reduced pressure (130 mbar). A flowable, transparent coating composition with a SiO 2 solids content of 49% was obtained, which has a water content of 0.4% by weight and which is storable for at least 3 months. The coating composition had a Brookfield viscosity of 2.24 Pa ^* s, measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 2500 s ^-1 .

Example 5:

In a glass beaker, 1000 g of a basic silica sol having a SiC "2 solids content of 30% by weight and an average particle size of 15 nm (Levasil® 200, HCStark GmbH, Leverkusen, Germany) with 100 g of a strongly acidic cationic ion exchanger ( Amberjet® 1200 (H), Sigma Aldrich Chemie GmbH, Taufkirchen, Germany), stirred for 30 minutes at room temperature, with a pH of 2.3, and the ion exchanger was subsequently removed by filtration.

In a flask, 20 g of this by means of ion exchange acidified silica sol with 20 ml of 2-propanol were added. 0.83 g of 3- (methacryloxy) propyltrimethoxysilane were added to the mixture with stirring and the reaction solution for 24 h at 25 ⁰ C is stirred.

Subsequently, the suspension was admixed with 132 g of 2-propanol, 6 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 0.1 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatiles were removed while passing through a small amount of lean air at 50 ⁰ C and under reduced pressure (130 mbar). There was obtained a flowable, transparent coating composition having a SiO 2 solids content of 48%, which has a water content of 0.2 wt .-% and which is storable for at least 3 months. The coating composition had a Brookfield viscosity of 1.36 Pa ^* s, measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 2500 s ^-1 .

Example 6:

In a flask, 20 g of the silicic acid sol acidified by means of ion exchange (Levasil® 200, Example 5) were admixed with 20 ml of 2-propanol. To the mixture, 0.66 g of 3- (methacryloxy) propyltrimethoxysilane were added un- ter stirring, and stirring the reaction solution for 24 h at 25 ⁰ C. Subsequently, the suspension was admixed with 132 g of 2-propanol, 6 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 0.1 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatiles were removed while passing through a small amount of lean air at 50 ⁰ C and under reduced pressure (130 mbar). A flowable, transparent coating composition having a SiO 2 solids content of 48%, which has a water content of 0.2% by weight and which is storable for at least 3 months, was obtained. The coating composition had a Brookfield viscosity of 1.40 Pa ^* s, measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 2500 s ^-1 .

Comparative Example 1

In a flask, 20 g of the silicic acid sol acidified by means of ion exchange (Levasil® 200, Example 5) were admixed with 20 ml of 2-propanol. 0.63 g of vinyltrimethoxysilane was added to the mixture un- ter stirring, and stirring the reaction solution for 24 h at 25 ⁰ C.

Subsequently, the suspension was admixed with 175 g of 2-propanol, 6 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 0.1 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatile components were removed under gen passage of little lean air at 50 ⁰ C and under reduced pressure (130 mbar). A solid, non-flowable but transparent coating composition having a SiCV solids content of 48% and having a water content of 0.2% by weight was obtained.

Example 7:

In a flask 200 g of 1-propanol 200 g of acidified by means of ion exchange silica sol (Levasil® 200, Example 5) were added. Wur- the 4.90 g of 3- stirring (methacryloxy) propyltrimethoxysilane was added and stirred the reaction solution for 24 h at 25 ⁰ C to the mixture.

Subsequently, the suspension was admixed with 300 g of 1-propanol, 60 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 2.0 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatiles were removed while passing through a small amount of lean air at 50 ⁰ C and under reduced pressure (130 mbar). There was obtained a flowable, transparent coating composition having a SiO 2 solids content of 47%, which has a water content of 0.2 wt .-% and which is storable for at least 3 months. The coating composition had a Brookfield viscosity of 1.30 Pa ^* s, measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 5000 s ^-1 .

Example 8: 170 g of 1-propanol were added to 170 g of the acidic acid solution (Levasil® 200, Example 5) acidified by means of ion exchange. 7.00 g of 3- (methacryloxy) propyltrimethoxysilane were added to the mixture with stirring and the reaction solution for 24 h at 25 ⁰ C is stirred.

Subsequently, the suspension was admixed with 260 g of 1-propanol, 51 g of trimethylolpropane triacrylate (Laromer® TMPTA, BASF AG, Ludwigshafen, Germany) and 1.7 g of a 10% solution of 4-methoxyphenol in Laromer® TMPTA. The volatiles were removed under passage of little lean air at 50 ⁰ C and under vermin- dertem pressure (130 mbar). A flowable, transparent coating composition having a SiO 2 solids content of 48%, which has a water content of 0.3% by weight and which is storable for at least 3 months, was obtained. The coating composition had a Brookfield viscosity of 2.46 Pa ^* s, measured on the cone and plate viscometer at 23 ^° C., with a shear rate of 2500 s ^-1 .

Example 9:

In a flask, 20 g of the silicic acid sol acidified by means of ion exchange (Levasil 200, Example 5) were admixed with 20 ml of 2-propanol. 0.83 g of 3- (methacryloxy) propyltrimethoxysilane were added to the mixture with stirring and the reaction solution for 24 h at 25 ⁰ C is stirred.

The suspension was then alkoxylated with 175 g of 2-propanol, 6 g of trimethylolpropane triacrylate (Laromer® PO 33 F, BASF AG, Ludwigshafen, Germany) and 0.1 g of a 10% solution of 4-methoxyphenol in Laromer® PO 33 F offset. The volatiles were removed while passing through a small amount of lean air at 50 ⁰ C and under reduced pressure (130 mbar). There was obtained a flowable, transparent coating composition having a SiO 2 solids content of 48%, which has a water content of 0.2 wt .-% and which is storable for at least 3 months. The coating composition had a Brookfield viscosity of 1.92 Pa ^* s, as measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 2500 s ^-1 .

Example 10:

In a flask, 20 g of the silicic acid sol acidified by means of ion exchange (Levasil® 200, Example 5) were admixed with 20 ml of 1-propanol. 0.73 g of 2-methylpropyltriethoxysilane were added to the mixture while stirring, and the reaction solution was stirred at 25 ^° C. for 24 h.

Subsequently, the suspension was admixed with 30 g of 1-propanol, 6 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 0.1 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatiles were removed while passing through a small amount of lean air at 50 ⁰ C and under reduced pressure (130 mbar). It was a flowable, transparent Be Stratified material having a SiO 2 solids content of 48%, which has a water content of 0.2 wt .-% and which is storable for at least 3 months. The coating composition had a Brookfield viscosity of 2.08 Pa ^* s, as measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 2500 S ^-1 .

Example 1 1:

100 g of a basic silica sol having a SiO 2 solids content of 30% by weight and an average particle size of 9 nm (Levasil 300, HCStark GmbH, Leverkusen, Germany) were mixed with 30 g of a strongly acidic cationic ion exchanger (Amberjet 1200 (FIG. H), Sigma Aldrich Chemie GmbH, Taufkirchen, Germany), stirred for 30 minutes at room temperature, with a pH of 2.3, and the ion exchanger was subsequently removed by filtration. In a flask, 100 g of the silicic acid acidified by means of ion exchange were mixed with 100 ml of 2-propanol. 6.18 g of 3- (methacryloxy) propyltrimethoxysilane were added to the mixture with stirring and the reaction solution for 24 h at 25 ⁰ C is stirred.

Subsequently, the suspension was admixed with 700 g of 2-propanol, 30 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF AG, Ludwigshafen, Germany) and 1.0 g of a 10% solution of 4-methoxyphenol in Laromer® 8863. The volatiles were removed while passing through a small amount of lean air at 50 ⁰ C and under reduced pressure (130 mbar). There was obtained a flowable, transparent coating composition having a SiO 2 solids content of 48%, which has a water content of 0.3 wt .-% and which is storable for at least 3 months. The coating composition had a Brookfield viscosity of 2.80 Pa ^* s, as measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 2500 s ^-1 .

Example 12:

300 g of a basic silica sol with a SiC "2 solids content of 40% by weight and an average particle size of 15 nm (Levasil® 200, HCStark GmbH, Leverkusen, Germany) were mixed with 30 g of a strongly acidic cationic ion exchanger in a glass beaker ( Amberjet® 1200 (H), Sigma Aldrich Chemie GmbH, Taufkirchen, Germany), stirred for 30 minutes at room temperature, with a pH of 2.4, and the ion exchanger was subsequently removed by filtration.

In a 750 ml Miniplant reactor with thermostat, impeller and breakwater 250 g of acidified by means of ion exchanger silica sol with 250 ml of 1-propanol were added. 13.75 g of 3 were added to the mixture with stirring.

(Methacryloxy) propyltrimethoxysilane was added and the reaction solution for 18 h at 25 ⁰ C stirred. Subsequently, the suspension was admixed with 250 ml of 1-propanol, 1 10 g of ethoxylated trimethylolpropane triacrylate (Laromer® 8863, BASF, Ludwigshafen, Germany), 0.125 g of 4-methoxyphenol and 0.5 g of triphenyl phosphite.

The volatiles were removed at temperatures of 45 ⁰ C (100 mbar) to 70 ⁰ C (50 mbar) and under reduced pressure. A flowable, transparent coating composition with a SiO 2 solids content of 46% was obtained, which has a water content of 0.1% by weight and which is storable for at least 3 months. The coating composition had a Brookfield viscosity of 0.96 Pa ^* s, as measured on the cone-plate viscometer at 23 ^° C., with a shear rate of 5000 s ^-1 .

Application Example 1 (Comparison):

Laromer® LR 8863 blended with 4% by weight Irgacure® 184 (photoinitiator, Ciba Spezialitatenchemie) is applied with a box doctor blade on bonder plate type 26 S 60 OC (Chemmetall) 30 microns thick and twice under a UV laboratory system (Company IST) (1 mercury medium pressure lamp with 120 W / cm) cured at a belt speed of 10m / min.

After 24 hours of storage under standard climatic conditions, the scratch resistance is determined. Scratching takes place by means of a hammer coated with a scrubbing fleece of the area 2.5 ^* 2.5 cm (Scotchbrite 7448 type S ultrafine, company 3M) (weight 500 g) which is passed over the coating in 10 or 50 double strokes without additional weight load becomes. The different matting in relation to the unloaded paint film due to the scratching is measured with a gloss meter (Mikro TRI-Gloss, Byk Gardener) at a measuring angle of 20 degrees. 56% (10 double strokes) and 64% (50 double strokes) are lost.

Coating Example 1

Analogously to Application Example 1, the SiO 2 -modified product prepared according to Example 7 is used instead of Laromer® LR 8863. The coated with this coating compound substrates show a loss of gloss of 6% (10 double strokes) and 11% (50 double strokes).

Claims

claims

1. A process for the preparation of silicate-containing organic Beschichtungsmas- sen, comprising the steps - adding an aqueous silica sol (K) having an average particle diameter of 5 to 150 nm with a silica content, calculated as SiO ₂ , from 10 to 60 wt % with a pH of 2 to 4 with 0 to 10 times the amount of water (based on the SiO ₂ content used) and 0.1 to 20 times the amount (based on the SiO ₂ content used) at a temperature of 10 to 60 ^° C. on at least one organic solvent (L) selected from the group consisting of ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 1-chloro-2-propanol, cyclopentanol, cyclohexanol, 1,4-dioxane, tetrahydrofuran, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 2-ethoxyethanol, 2-methyl-2-propanol, 2- Methoxyethanol, dimethylformamide, acetonitrile and acetone,

at least one compound (S) which has at least one at least monoalkoxylated silyl group and at least one group which is reactive with the organic coating composition, in an amount of from 0.1 to 20 μmol (S) per m ² surface area of (K) , and optionally further solvent (L),

- placing the mixture thus obtained with the organic coating composition and

- At least partial distillation of the organic solvent (L).

2. The method according to claim 1, characterized in that the organic solvent used (L) forms an azeotrope with water under the conditions of distillation.

3. The method according to any one of the preceding claims, characterized in that the reactive groups of the compound (S) are selected from the group consisting of epoxy, amino, acid, hydroxy, isocyanate and radically polymerizable groups.

4. The method according to claim 3, characterized in that the compound (S) is selected from the group consisting of 3

(Methacryloxy) propyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3- (methacryloxy) propyltriethoxysilane, 3- (methacryloxy) propylmethyldimethoxysilane, 3- (methacryloxy) methyltriethoxysilane, 3- (methacryloxy) methyl (methyl) dimethoxysilane, and 3- (methacryloxy) methyl (methyl) diethoxysilane.

5. The method according to any one of the preceding claims, characterized in that pH of the reaction mixture from the addition of the organic solvent (L) until the end of the distillation is less than 5.

6. The method according to any one of the preceding claims, characterized in that the organic coating material has a viscosity of not more than 4000 mPas.

7. The method according to any one of the preceding claims, characterized marked, that it is the organic coating material components for one- or two-component polyurethane coatings, epoxy resins, melamine-formaldehyde resins or radiation-curable compounds.

8. The method according to any one of the preceding claims, wherein the organic coating composition is a radiation-curable compounds, characterized in that the coating composition is added at least one inhibitor against a radical polymerization.

9. The method according to claim 8, characterized in that as inhibitor at least one aerobic inhibitor is contained.

10. The method according to claim 9, characterized in that one brings the coating composition with an oxygen-containing gas in contact.

1 1. A method according to claim 8, characterized in that the inhibitor is selected from the group consisting of hydroquinone monomethyl ether, tetramethyl-piperidine-N-oxyl, phenothiazine and triphenyl phosphite.

12. A process for coating substrates, characterized in that one obtained according to one of claims 8 to 11 silicate particle-containing

Coating composition with at least one photoinitiator and optionally further typical paint additives added, applied to a substrate and preferably exposed under inert gas with UV radiation.

13. Use of coating compositions obtained according to one of claims 1 to 11 for coating substrates.