EP1910479A2

EP1910479A2 - Paints containing particles

Info

Publication number: EP1910479A2
Application number: EP06762278A
Authority: EP
Inventors: Christoph Briehn; Volker Stanjek; Jürgen Pfeiffer; Felicitas Schauer
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2005-07-22
Filing date: 2006-06-29
Publication date: 2008-04-16
Also published as: WO2007009569A3; WO2007009569A2; CN101228239A; DE102005034347A1; US20080226901A1; JP2009503129A; KR20080029004A

Abstract

The invention relates to coatings (B), produced from coating formulations (B1), containing a) a paint resin (L) with reactive groups, b) a paint hardener (H) with reactive groups by means of which the paint hardener can react with the reactive groups of the paint resin (L), c) particles (P) and d) optionally solvent, wherein a) the hardened coating (B) aa) on the surface thereof or ab) in the layers adjacent to the surface which when measured from the surface are 1000 nm thick or ac) both on the surface and in the layers adjacent to the surface which when measured from the surface are 1000 nm thick has an increased concentration of particles (P) than in the interior thereof and wherein b) the particles (P) may be obtained by a reaction of colloidal metal or silicon oxide sols (P1) with organosilanes (A), selected from general formulae (I) and (II), where R1, R2, R4, A, X, Y, m, n and q have the meanings given in claim 1.

Description

Paints containing particles

The invention relates to particle-containing coatings which have on their surface a higher concentration of particles than in their interior, and their use.

Particles - in particular nanoparticles - containing coating systems are state of the art. Corresponding coatings are described for example in EP 1 249 470, WO 03/16370, US 20030194550 or US 20030162015. The particles lead to an improvement in the properties of the corresponding coatings, in particular with regard to their scratch resistance and optionally also their chemical resistance.

A frequently occurring problem when using the - usually inorganic - particles in organic coating systems consists in a usually insufficient compatibility of particles and paint matrix. This can lead to the particles not being able to be dispersed sufficiently well in a coating matrix. In addition, even well-dispersed particles can settle at longer stand or storage times, possibly forming larger aggregates or agglomerates, which can not or only with difficulty be separated into the original particles during a redispersion. The

Processing such inhomogeneous systems is in any case extremely difficult, often even impossible. Lacquers which have smooth surfaces after their application and hardening can generally not be produced in this way or can only be produced by cost-intensive processes.

Therefore, it is advantageous to use particles which have on their surface organic groups, which to a lead to better compatibility with the paint matrix. In this way, the inorganic particle is "masked" by an organic shell, in which case particularly favorable coating properties can be achieved if the organic functions on the particle surfaces are also reactive with respect to the coating matrix, so that under the respective curing conditions of the corresponding coating material It is thus possible to chemically incorporate the particles into the matrix during coating curing, which often results in particularly good mechanical properties but also improved resistance to chemicals Such systems are described, for example, in DE 102 47 359 A1, EP 832 947 A or EP 0 872 500 A1 A disadvantage of the systems described here is the generally relatively high proportions of the comparatively expensive nanoparticles in the total solids content of the paint.

Furthermore, the use of coatings containing a nanoparticle-modified binder is also known. These can be prepared by reacting the reactive functionalized particles with a binder having a complementary function. Ie. Here, the organofunctional particle is chemically incorporated into the paint matrix not only during paint curing but also during binder production. Such systems are described for example in EP 1 187 885 A or WO 01/05897. However, they have the disadvantage of being relatively expensive to produce, which leads to high production costs.

In a particularly important type of paint, a coating resin of hydroxy-functional prepolymers, in particular of hydroxy-functional polyacrylates and / or polyesters, used in the paint curing with a isocyanate-functional hardener (polyurethane coatings) and / or a melamine hardener (melamine coatings) are reacted. The polyurethane coatings are characterized by particularly good properties. In particular, polyurethane coatings have superior chemical resistance, while melamine coatings generally have better scratch resistance. Typically, these types of paints are used in particularly high-quality and demanding fields of application, for example as clearcoats or topcoats for OEM coatings in the automotive and vehicle industry. Likewise, most automotive refinish topcoats are of such systems. The layer thicknesses of these coatings are typically in the range from 20 to 50 μm.

In polyurethane paint systems, a distinction is generally made between the so-called 2K and 1K systems. The former consist of two components, one of which consists essentially of the Isocyanathärter, while the paint resin is contained with its isocyanate-reactive groups in the second component. Both components must be stored and transported separately and may only be mixed shortly before processing, since the finished mixture has only a very limited pot life. Often cheaper, therefore, are the so-called IK systems, which consist of only one component in which there is a hardener with protected isocyanate groups in addition to the paint resin. 1-component paints are thermally cured, whereby the protecting groups of the isocyanate units are split off, and the deprotected isocyanates can then react with the paint resin. Typical baking temperatures of such 1-component paints are 120-160 ⁰ C. In the case of

Melamine paints are usually 1-component paints, the baking temperatures are typically in a comparable temperature range. Especially with these high-quality paints, a further property improvement would be desirable. This applies in particular to vehicle topcoats. So especially the achievable scratch resistance of conventional car paints is not sufficient, so it is z. B. in the car wash by particles in the wash water to a noticeable scratching of the paint. In the long term, the gloss of the paint is sustainably damaged. Here would be desirable formulations that can achieve better scratch resistance.

A particularly advantageous way of achieving this object is the use of particles which have on their surface organo-functions which are reactive with the paint resin or with respect to the hardener. In addition, these lead

Organ functions on the particle surface to mask the particles and thus improve the compatibility of particles and paint matrix.

Such particles with suitable organ functions are already known in principle. Like their use in coatings, they are described, for example, in EP 0 768 351, EP 0 832 947, EP 0 872 500 or DE 10247359.

In fact, the scratch resistance of paints can be significantly increased by the incorporation of such particles. However, no optimal results are obtained with all of the methods described in the prior art when using these particles. In particular, the corresponding coatings have such high particle contents that a

Use of such paints in large series paints alone for cost reasons will be difficult to achieve. In WO 01/09231, paint-containing paint systems are described, which are characterized in that there are more particles in a surface segment of the paint than in a bulk segment. The advantage of this particle distribution is the comparatively low particle concentration, which is needed for a significant improvement in the scratch resistance. The desired high affinity of the particles to the paint surface is achieved by applying a silicone resin as a surface-active agent to the particle surfaces. The modified particles thus obtained have - for silicones often typical - a relatively low surface energy. As a result, they preferably arrange themselves on the surface of the paint matrix. A disadvantage of this method, however, is the fact that not only the silicone resin modification of the particles, but also the preparation of the silicone resins required for this purpose is itself technically complicated. The latter is particularly problematic because it is necessary for achieving a good scratch resistance, the silicone resins with organ functions, eg. As carbinol functions to provide over which the correspondingly modified particles can be chemically incorporated in the paint curing in the paint. Such functionalized silicone resins are not available commercially or only to a very limited extent. Above all, however, the choice of possible organ functions in this system is relatively limited. Therefore, in this system, as well as in all other systems according to the prior art, no optimal results are achieved.

The object of the invention was therefore the development of a paint system that overcomes the disadvantages of the prior art. The invention provides coatings (B) prepared from coating formulations (B1) which contain a) 20-90% by weight, based on the solids content, of a coating resin (L) having reactive groups, b) 0-90% by weight , based on the solids content, one

Paint hardener (H), which has reactive functions with which it can react with the reactive groups of the coating resin (L) in the paint curing, c) 0.05 to 15 wt .-%, based on the solids content, of particles (P ) and d) 0 - 90 wt .-%, based on the total coating formulation (Bl), of a solvent or a solvent mixture, wherein a) the cured coating (B) aa) on its surface or ab) in the near-surface layers measured 1000 nm thick from the surface or ac) have a higher concentration of the particles (P) at their surface as well as in the near-surface layers measured 1000 nm thick than in their interior, and in which b) the particles (P) are obtainable by reacting colloidal metal or silicon oxide sols (P1) with organosilanes (A) selected from the general formula (I) and (II)

(R ¹ O) ₃ _-H (RS) _n Si-AX (I)

wherein R ^{1 is} hydrogen, alkyl, cycloalkyl or aryl radicals each with 1 to 6 C atoms, wherein the carbon chain may be interrupted by non-adjacent oxygen, sulfur or NR ³ groups,

R ^{2 is} alkyl, cycloalkyl, aryl or arylalkyl radicals having in each case 1 to 12 C atoms, where the carbon chain may be interrupted by nonadjacent oxygen, sulfur or NR ³ groups,

R ^{3 is} hydrogen, alkyl, cycloalkyl, aryl, arylalkyl, aminoalkyl or aspartate, R 1 is hydrogen or any organic radical,

A is a divalent, optionally substituted alkyl, cycloalkyl or aryl radical having 1-10 carbon atoms, which may optionally be interrupted by oxygen, sulfur or NR ³ - groups, X is an organo function which reacts in the paint curing with a chemical reaction Y is an organo function which - optionally after the cleavage of the Si-Y bond - in the paint curing a chemical reaction with functions of the paint resin (L) or the

Paint hardener (H) can mean, and n the values 0, 1 or 2, m the values 0, 1 or 2 and q can take the values 0 or 1.

The solids content comprises those coating components which remain in the paint during the curing of the paint.

The accumulation of the particles on the surface and / or in the near-surface layers is preferably limited to the upper 500 nm or 200 nm and particularly preferably to the uppermost 100 nm of the coatings (B). The invention is based on the discovery that the particles (P) during application and curing of the paint are preferably arranged on or near the surface of the coating (B) according to the invention. This discovery is particularly noteworthy because the silane modification of the particles (P) causes the particles on their surfaces reactive organic groups -. As hydroxyl functions, primary or secondary amine functions, isocyanate functions, protected isocyanate functions - have. These relatively polar organ functions commonly do not result in surfaces with particularly low surface energies. A preferred independent arrangement of the particles at or near the paint surface was therefore not to be expected, the near-surface distribution of the particles (P) in the coating (B) is completely surprising for the expert.

The near-surface distribution of the particles (P) in the cured coating (B) means that when using the particles (P) in paint systems, the scratch resistance of the resulting coating (B) is not proportional to

Concentration of the particles used changes. On the contrary, even small or very small contents of particles (P) are sufficient in order to achieve a significant improvement in the scratch resistance of the coatings (B), whereas z. T. significantly higher levels of particles (P) no more significant increase in scratch resistance can achieve more.

The small contents of the usually relatively expensive particles (P) allow for a comparatively cost-effective production of highly scratch-resistant paints, on the other hand reduce the low particle contents - possibly negative - influences the particles on other paint properties, such. B. Elasticity, transparency or surface smoothness. Thus, the coating (B) according to the invention with low contents of synthetically readily accessible particles represents a great advantage over the prior art.

The enrichment of the particles according to the invention on the surface preferably results from an independent arrangement of the particles. That when applying the coating formulation of the invention (Bl) are no special process steps - such. the application of different paint layers, each with different particle concentrations or aftertreatment of the already applied coating with a particle dispersion - required to achieve the particle distribution according to the invention.

The coating formulations (B1) which can be processed to give the coatings (B) according to the invention are likewise provided by the present invention.

The paint resin (L) and the paint hardener (H) preferably have sufficiently many reactive groups that a three-dimensional polymer network can form during the curing of the coating formulation (B1). The paint resin (L) preferably contains a hydroxyl-functional (pre) polymer, particularly preferably hydroxyl-functional polyacrylates and / or polyesters. The paint curing agent (H) preferably contains protected and / or unprotected isocyanate groups and / or contains melamine-formaldehyde resins.

In a preferred embodiment of the invention, the coatings (B) are prepared from coating formulations (B1) which a) 30-80 wt .-%, based on the solids content of the paint resin (L), b) 5-60 wt .-%, based on the solids content of the paint curing agent (H), c) 0.1-12 wt .-%, based on the solids content, to

Particles (P) and d) 0 to 70 wt .-%, based on the total coating formulation (Bl), a solvent or a solvent mixture.

Particularly preferably, the coating formulations contain

(Bl) a) 40-70 wt .-%, based on the solids content, of

Lackharzes (L), b) 15-50 wt .-%, based on the solids content of the paint curing agent (H), c) 0.5 to 8 wt .-%, based on the solids content of particles (P) and d ) 10 - 60 wt .-%, based on the total coating formulation (Bl), of one or more solvents.

The proportion of solvent or solvents in the total coating formulation (Bl) is particularly preferably from 10 to 50% by weight.

The coating formulations (B1) for the coatings (B) according to the invention are typically processed by the following working steps: coating of a substrate, drying and curing, in which case the last two steps can also take place simultaneously, in particular in 2-component paints.

The content of particles (P) in the coating (B) is preferably at 0.1 to 12 wt .-%, based on the solids content, particularly preferably at 0.2 to 8 wt .-%. In very particularly advantageous embodiments of the invention, the content of particles (P) at 0.5 to 5 wt .-%, based on the solids content, in particular 0.7 to 3 wt .-%.

The coatings (B) according to the invention are preferably used as clearcoats and / or topcoats, in particular for automotive OEM or automotive refinishes.

In the case of the organosilanes (A), the groups RΛ are preferably

Methyl or ethyl radicals. The groups R 1 preferably represent alkyl radicals having 1 to 6 carbon atoms or phenyl radicals, in particular methyl, ethyl or isopropyl radicals. R 1 preferably has at most 10 carbon atoms, in particular at most 4 carbon atoms. R ⁴ preferably represents hydrogen or an alkyl radical having 1-10, particularly preferably 1-6, carbon atoms, in particular methyl or ethyl radicals. A is preferably a divalent alkyl radical having 1-6 carbon atoms which may optionally be interrupted by oxygen, sulfur or NR.sup.1 groups. A particularly preferably represents a (CH 2) 3 group or a CH 2 - group.

In a preferred embodiment of the invention, the organosilanes (A) used are compounds of the general formula (I) in which the function X is an isocyanate or-particularly preferably-a protected isocyanate function. The latter releases an isocyanate function upon thermal treatment. Preferred elimination temperatures of the protecting groups are present at 80 to 200 ⁰ C, particularly preferably at 100 to 170 ⁰ C. The protecting groups may secondary or tertiary alcohols such as isopropanol or t-butanol, CH- acidic compounds, such as. For example, diethyl malonate, acetylacetone, ethyl acetoacetate, oximes, such as. B. formaldoxime, acetaldoxime, butane oxime, cyclohexanone oxime, acetophenone oxime, benzophenone oxime or diethylene glycol, lactams, such as. Caprolactam, valerolactam, butyrolactam,

Phenols, such as phenol, o-methylphenol, N-alkylamides, such as. N-methylacetamide, imides such as phthalimide, secondary amines such as e.g. Diisopropylamine, imidazole, 2-isopropylimidazole, pyrazole, 3,5-dimethylpryazole, 1, 2, 4-triazole and 2.5 dimethyl-1, 2, 4-triazole can be used. Preference is given to protecting groups, such as butane oxime, 3, 5-Diroethylpyrazol, caprolactam, diethyl malonate, methyl malonate, acetoacetic ester, diisopropylamine, pyrrolidone, 1, 2, 4-triazole, imidazole and 2-Isopropylimidazol used. Particular preference is given to using protecting groups which allow a low stoving temperature, such. B.

Diethyl malonate, dimethyl malonate, butane oxime, diisopropylamine, 3, 5-dimethylpyrazole and 2-isopropylimidazole.

The corresponding particles (P) with protected

Isocyanate groups are preferably used in coating formulations (B1) which contain as curing agent (H) a compound which also has protected isocyanate functions. The corresponding coating formulations (B1) are thus IK polyurethane coatings. In a particularly preferred embodiment of the invention, in these coating formulations (B1) the protected isocyanate groups of the particles (P) are provided-at least predominantly-with protective groups which have a lower cleavage temperature than all or at least the majority of the protective groups of the protected isocyanate groups of the paint curing agent (H) . X preferably represents a hydroxyl or thiol function, a group of the formula NHR 1, a heterocyclic ring containing an NH function or an epoxide ring. In a particularly preferred embodiment, X represents a piperazine ring. R 5 has the meanings of R 1 on. If X represents an epoxide ring, this is before, during or after the reaction of the silane (A) with the particles (Pl) by a suitable method, for. B. opened by a reaction with ammonia, an amine, water or an alcohol or an alcoholate.

If silanes (A) of the general formula (II) are used in the preparation of the particles (P), the ring structure of this silane is broken during particle production by the attack of a hydroxyl group of the particles (P1) on the silicon atom of the silane (A) the Si-Y bond opened. In this case, Y is preferably a function which, after this cleavage of the Si-Y bond, is a hydroxyl or

Thiol function or a group of the formula NHR ^ represents.

Particular preference is given to using organosilanes (A) which correspond to the general formulas (III) or (IIIa)

in which

B is oxygen, sulfur, carbonyl, ester, amide or NR ^ represents,

R ^{6 has} the meanings of R 1, x can assume the values from 0 to 10 and the remaining variables have the meanings given in the general formulas (I) and (II).

In a further particularly preferred embodiment of the invention, the particulate sols (P1) are functionalized with organosilanes (A) which correspond to the general formulas (IV) or (IVa)

all variables having the meanings given in the general formulas (I) (III).

Very particular preference is given to using organosilanes (A) as compounds of the general formulas (V) or (VI)

(R ¹ O) ₂ - _J ¹ R ² _U Si-AN NH (VI),

where all variables have the meanings given above exhibit.

In the preparation of the particles (P), any mixtures of the silanes (A) with other silanes (S1), silazanes (S2) or siloxanes (S3) can be used for surface modification of the particulate sols (P1) in addition to the silanes (A). The silanes (S1) have either hydroxysilyl groups or else hydrolyzable silyl functions, the latter being preferred. In addition, these silanes can have further organ functions, but it is also possible to use silanes (SI) without further organ functions. As silazanes (S2) or siloxanes (S3) hexamethyldisilazane or hexamethyldisiloxane are particularly preferably used. Preferably, the proportion by weight of silanes (A) in the total amount formed from silanes (A) and (S1), silazanes (S2) and siloxanes (S3) is at least 50% by weight, more preferably at least 70% by weight and 90% by weight, respectively. In a further particularly preferred embodiment of the invention, the use of the compounds (S1), (S2) and (S3) is completely dispensed with.

The preparation of the particles (P) is based on colloidal silicon or metal oxide sols (P1) which are generally used as a dispersion of the corresponding submicron-sized oxide particles in an aqueous or non-aqueous

Solvent present. Among others, the oxides of the metals aluminum, titanium, zirconium, tantalum, tungsten, hafnium and tin can be used. Preference is given to using colloidal silica. This is generally a dispersion of silica particles in an aqueous or nonaqueous solvent. As a rule, the silica sols are 1-50% solutions, preferably a 20-40% solution. Typical solvents are in addition to water, especially alcohols, especially alcohols having 1 to 6 carbon atoms, often other isopropanol but also other low molecular weight alcohols, such as. As methanol, ethanol, π-propanol, n-butanol, isobutanol and t-butanol -, wherein the average particle size of

Silica particles (P1) at 1 - 100 ran, preferably at 5 - 50 nm, more preferably at 8 - 30 nm.

The preparation of the particles (P) from the colloidal silicon or metal oxides (P1) and the organosilanes (A) preferably takes place directly during the mixing of the reactants, if appropriate in the presence of further solvents and water. The order of addition of the individual reactants is arbitrary. However, preference is given to adding the silanes (A) - optionally in a solvent and / or in mixtures with other silanes (S1), silazanes (S2) or siloxanes (S3) - to the aqueous or organic particulate sol (P1). This sol may be acidic, e.g. By hydrochloric acid or trifluoroacetic acid, or basic, e.g. B. by ammonia stabilized. The reaction is generally carried out at temperatures of 0-200 ^° C., preferably at 20-80 ^° C., and more preferably at 20-60 ^° C. The reaction times are typically from 5 minutes to 48 hours, preferably from 1 to 24 hours. Alternatively, it is also possible to add acidic, basic or heavy metal-containing catalysts. However, preference is given to omitting the addition of separate catalysts.

Since the colloidal silicon or metal oxide sols (P1) are often present in aqueous or alcoholic dispersion, it may be advantageous for the solvent (s) during or after the preparation of the particles (P) against another solvent or against another solvent mixture exchange. This can be done for example by distillative removal of the original solvent, wherein the new solvent or solvent mixture can be added in one or more steps before, during or even after distillation. Suitable solvents may be, for example, water, aromatic or aliphatic alcohols, where aliphatic alcohols, in particular aliphatic alcohols having 1 to 6 carbon atoms (eg., Methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, the various regioisomers of pentanol and hexanol), esters (eg ethyl acetate, propyl acetate, butyl acetate, butyl diglycol acetate, methoxypropyl acetate), ketones (eg acetone, methyl ethyl ketone), ethers (eg diethyl ether, t-butyl methyl ether, THF), aromatic solvents (toluene, the various regioisomers of xylene, but also mixtures such as solvent naphtha), lactones (eg, butyrolactone, etc.) or lactams (eg, N-methylpyrrolidone). In this case, aprotic solvents or solvent mixtures which consist exclusively or at least partly of aprotic solvents are preferred. Aprotic solvents are advantageous, at least when used in isocyanate-curing coating formulations (B1), ie in IK or 2K polyurethane coatings, since protic solvents, like water, are reactive towards isocyanate functions, leading to undesirable side reactions between hardener (H) and the solvent can lead. In addition to the preparation of a particle dispersion and insulation of the particles (P) is conceivable as a solid, eg. B. by distillative removal of the / the solvent after the particle production.

In a particularly advantageous embodiment of the invention, organosilanes (A) are used in the preparation of the particles (P). of the general formulas (I) or (VI) in which the spacer A is a CH 2 bridge, or cyclic organosilanes of the general formulas (III), (IIIa), (IVa) or (V). These silanes are characterized by a particularly high reactivity towards the hydroxyl groups of the particles (P1), so that the functionalization of the particles can be carried out particularly rapidly and at low temperatures, in particular already at room temperature.

Are there used organosilanes (A), which have only monofunctional silyl, d. H. Silanes of the general formulas (I), (II), (III), (IIIa), (IV), (IVa), (V) or (VI) with n or rα = 2, may be used in the preparation of the particles (P) can be dispensed with the addition of water, since the monoalkoxysilyl groups, the reactive cyclic silanes can react directly with the hydroxyl functions on the surface of the particles (Pl). If, however, silanes (A) are used with di- or trifunctional silyl groups (ie silanes of the general formulas (I), (II), (III), (IIIa), (IV), (IVa) or (VI) with n or m = 0 or 1), the presence or addition of water in the preparation of the particles (P) is often advantageous because the alkoxysilanes then not only with the Si-OH functions of the particles (Pl), but - after their Hydrolysis - can also react with each other. This results in particles (P), which have a shell of interconnected silanes (A).

The coating resins (L) contained in the coating formulations (B1) preferably comprise hydroxyl-containing prepolymers, more preferably hydroxyl-containing polyacrylates or polyesters. Such suitable for the paint preparation hydroxyl-containing polyacrylates and polyesters are well known in the art and in the relevant literature many times. They are manufactured by many manufacturers and distributed commercially.

The coating formulations (B1) can be 1-component (1K) or 2-component (2K) coatings. In the first case, melamine hardeners, tris (aminocarbony) triazines and / or hardeners which possess protected isocyanate groups are preferably used as paint hardeners (H). In the second case, compounds having free isocyanate groups are preferably used as hardener (H). Both melamine hardener and hardener with protected or unprotected NCO groups are well known in the prior art and described in many cases in the corresponding literature. They too are commercially available and are distributed by numerous manufacturers.

In a preferred embodiment of the invention, the paint curing agent (H) contains free or protected isocyanate groups. Most commonly used for this purpose di- and / or polyisocyanates, which may have been previously provided with the respective protective groups. As isocyanates, it is possible in principle to use all customary isocyanates, as are frequently described in the literature. Common diisocyanates are, for example, diisocyanatodiphenylmethane (MDI), both in the form of crude or industrial MDI and in the form of pure 4,4'- or 2,4'-isomers or mixtures thereof, tolylene diisocyanate (TDI) in the form of its various regioisomers, diisocyanatonaphthalene (NDI), isophorone diisocyanate (IPDI), perhydrogenated MDI (H-MDI), tetramethylene diisocyanate, 2-methylpentamethylene diisocyanate, 2, 2, 4-trimethylhexamethylene diisocyanate,

Dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1,3-diisocyanato-4-methylcyclohexane or also Hexamethylene diisocyanate (HDI). Examples of polyisocyanates are polymeric MDI (P-MDI), triphenylmethane triisocyanate and also all isocyanurate or biuret trimers of the diisocyanates listed above. In addition, it is also possible to use further oligomers of the abovementioned isocyanates with blocked NCO groups. All di- and / or polyisocyanates can be used individually or in mixtures. Preference is given here to the isocyanurate and biuret trimerates of the comparatively UV-stable aliphatic isocyanates, particularly preferably the trimers of HDI and IPDI.

If isocyanates with protected isocyanate groups are used as coating hardener (H), the same compounds are suitable as protective groups, as have already been described in the description of particles modified with protected isocyanates (P). The ratio of optionally blocked isocyanate groups of all constituents of the coating formulation (B1) to the isocyanate-reactive groups of all constituents of the coating formulation (B1) is usually from 0.5 to 2, preferably from 0.8 to 1.5 and more preferably from 1, 0 to 1.2 selected.

Of course, the organo-functions of the silanes to be used for particle modification (i.e.

Functions X and Y in the general formulas (I) and (II), the functions of the paint resin (L) and the hardener (H)) in a suitable manner to one another.

Furthermore, the coating formulations (B1) may also contain the customary solvents and the additives and coating components customary in coating formulations as component (E). Amongst others, flow aids, surface-active substances, adhesion promoters, light stabilizers such as UV absorbers and / or radical scavengers, thixotropic agents and other solids. To produce the respective desired property profiles of both the coating formulations (B1) and the cured coatings, such additives are preferably added. Likewise, the coating formulations (Bl) may also contain pigments.

In a preferred method, the coating formulations (B1) according to the invention are prepared by the

Particles (P) are added during the mixing process as a powder or as a dispersion in a suitable solvent. In addition, however, a further method is preferred in which first of all a masterbatch is produced from the particles (P) and one or more coating components, with particle concentrations> 15% by weight, preferably> 25% by weight and particularly preferably> 30% by weight .-%. In the preparation of the coating formulations (B1) according to the invention, this masterbatch is then mixed with the other coating components. Used in the production of the masterbatch by a

Particle dispersion, it may be advantageous if the solvent of the particle dispersion in the course of masterbatch production is removed, for. B. via a distillation step, or exchanged for another solvent or solvent mixture.

The inventive coatings (B) can be used to coat any desired substrates for improving scratch resistance, abrasion resistance or chemical resistance. Preferred substrates are plastics, such as

Polycarbonate, polybutylene terephthalate, polymethyl methacrylate, polystyrene or polyvinyl chloride as well as applied in an upstream step basecoats. The coatings (B) particularly preferably serve as scratch-resistant clearcoats or topcoats, in particular in the vehicle industry. The coating formulations (B1) can be applied by any methods, such as dipping, spraying, and casting methods. Also an application of the coating formulation (Bl) to a basecoat for a "wet on wet" method is possible Curing is generally carried out by heating under the particular conditions required (2K coatings typically at 0 -. 100 ⁰ C, preferably at 20 - 80 ⁰ C, 1K coating at 100 - 200 ° C preferably at 120 - paint curing can be accelerated by the addition of suitable catalysts 160 ⁰ C) of course suitable catalysts are, are, in particular, acidic, basic as well as heavy-metal-containing compounds...

All symbols of the above formulas have their meanings independently of each other. In all formulas, the silicon atom is tetravalent.

Unless otherwise indicated, all amounts and percentages are by weight, all pressures are 0.10 MPa (abs.) And all temperatures are 20 ^° C.

Examples:

Synthesis Example 1: Preparation of an alkoxysilane with diisopropylamine-protected isocyanate groups (silane 1). There are (from Borchers GmbH catalyst VP 0244) provided 86.0 g of diisopropylamine and 0.12 g Borchi® catalyst and heated to 80 ⁰ C. Within 1 h 150.00 g of isocyanatomethyl-trimethoxysilane are added dropwise and the mixture for Stirred at 60 ⁰ C for 1 h. ¹ H-NMR and IR spectroscopy show that the isocyanatosilane has been completely reacted.

Synthesis Example 2: Preparation of an alkoxysilane with diisopropylamine-protected isocyanate groups (silane 2).

There are (from Borchers GmbH catalyst VP 0244) provided 74.5 g of diisopropylamine and 0.12 g Borchi® catalyst and heated to 80 ⁰ C. 150.00 g of 3- isocyanatopropyl-trimethoxysilane are added dropwise within 1 h and the mixture stirred for I h at 60 ⁰ C. ¹ H-NMR and IR spectroscopy show that the isocyanatosilane has been completely reacted.

Synthesis Example 3 Preparation of SiO 2 Nanosol Particles Modified with Blocked Isocyanate Groups 1.40 g of the diisopropylamine-protected isocyanatosilane prepared according to Synthesis Example 1 (silane 1) are dissolved in 1.0 g of isopropanol. Then, within 30 minutes, 20 g of a SiO 2 organosol (IPA-ST from Nissan Chemicals,

30 wt .-% SiC> 2, 12 nm average particle diameter) is added dropwise and the pH is by adding trifluoroacetic on

3.5 set. The resulting dispersion is stirred for 3 h at 60 ⁰ C and then for 18 h at room temperature. Thereafter, 18.1 g of methoxypropyl acetate are added. The mixture is stirred for a few minutes and then distilled off a large part of the isopropanol at 70 ⁰ C. Ie. It is distilled until the nanoparticle sol has been concentrated to 29.4 g. The result is a dispersion having a solids content of 25.5 wt .-%. The SiO 2 content is 20.8% by weight and the content of protected isocyanate groups in the dispersion is 0.17 mmol / g. The dispersion is slightly cloudy and shows a Tyndall effect.

Synthesis Example 4: Preparation of blocked Isocyanate-modified SiO 2 nanosol particles

1.54 g of the diisopropylamine-protected isocyanatosilane prepared according to Synthesis Example 2 (silane 2) are initially charged. Then, within 30 minutes, 20 g of a SiO 2 organosol (IPA-ST from Nissan Chemicals, 30% by weight SiC> 2,

12 nm average particle diameter) and the pH is adjusted to 3.0 by addition of trifluoroacetic acid. The obtained dispersion for 3 hours at 6O ⁰ C and then stirred for 24 h at room temperature. The resulting dispersion has a solids content

(Particle content) of 35 wt .-%, the SiO 2 content is 27.9

% By weight and the content of protected isocyanate groups in the dispersion is 0.23 mmol / g. The dispersion is slightly cloudy and shows a Tyndall effect.

Examples 1 to 7: Preparation of a 1-component coating formulation containing SiO 2 nanosol particles which have been modified with blocked isocyanate groups To prepare a coating formulation according to the invention, an acrylate-based

Paint polyol having a solids content of 52.4% by weight (solvent: solvent naphtha, methoxypropyl acetate (10: 1)), a hydroxyl group content of 1.46 mmol / g resin solution and an acid number of 10-15 mg KOH / g with Desmodur® BL 3175 SN from Bayer (butanoxime-blocked polyisocyanate, blocked NCO content of 2.64 mmol / g). The amounts of the respective components used can be found in Table 1. Subsequently, the in Table 1. specified amounts of the dispersion prepared according to Synthesis Example 3 was added. In each case, molar ratios of protected isocyanate functions to hydroxyl groups of 1.1: 1 are achieved. Further, 0.01 g each of a dibutyltin dilaurate and 0.03 g of a 10 wt .-% solution ADDID® 100 from TEGO AG (polysiloxane-based leveling agent) in isopropanol, resulting in coating formulations with about 50% by weight solids. These initially slightly cloudy mixtures are stirred for 48 h at room temperature to give clear coating formulations.

Desmophen® Desmodur® Nanosol ParticleA 365 BA / X BL 3175 SN after Syn. Content ¹¹ bsp. 3

Example 1 * 4.50 g 2.73 g 0.0 g 0.0%

Example 2 4.50 g 2.72 g 0.30 g 1.7%

Example 3 4.50 g 2.71 g 0.38 g 2.2%

Example 4 4.50 g 2.70 g 0.57 g 3.2%

Example 5 4.50 g 2, 69 g 0.76 g 4.2%

Example 6 4.50 g 2.64 g 1.52 g 8.2%

Example 7 4.50 g 2.16 g 2.11 g 11.2%

Table 1: Formulations of the lacquers (Example 1-7) * not according to the invention

D proportion of the particles (P) according to Synthesis Example 3 in the total solids content of the respective paint formulation

Example 8: Preparation of a 1K coating formulation containing SiO 2 nanosol particles modified with blocked isocyanate groups

To produce a coating according to the invention, 4.50 g of an acrylate-based coating polyol having a solids content of 52.4% by weight (solvent: solvent naphtha, Methoxypropylacetat (10: 1)), a hydroxyl group content of 1.46 mmol / g resin solution and an acid number of 10 - 15 mg KOH / g with 2.71 g Desmodur® BL 3175 SN from. Bayer (butanoxime-blocked polyisocyanate, blocked NCO content of 2.64 mmol / g). Subsequently, 0.29 g of the after

Synthesis Example 4 prepared, the diisopropylamine-blocked isocyanate group-modified SiO 2 ~

Contains nanosol particles. This corresponds to a molar ratio of protected isocyanate functions to hydroxyl groups of 1.1: 1. The content of particles after

Synthesis Example 4 on the total solids content is 2.2 wt .-%. Furthermore, 0.01 g of a dibutyltin dilaurate and 0.03 g of a 10% strength by weight solution ADDID® 100 from TEGO AG (polysiloxane-based leveling agent) are mixed in isopropanol, giving a coating formulation of about 50% by weight. % Solids content is obtained. This initially slightly turbid mixture is stirred for 48 h at room temperature to give a clear coating formulation.

Preparation and Evaluation of Paint Films from the Paint Formulations of Examples 1 - 8.

The coating compositions from Examples 1 to 8 are in each case wound up on a glass plate by means of a film applicator Coatmaster® 509 MC from Erichsen using a squeegee with a gap height of 120 μm. Subsequently, the obtained

Coating films in a circulating air dryer for 30 minutes at 70 ⁰ C and then dried for 30 min. At 150 ⁰ C. Both the coating formulations of the examples and of the comparative examples give optically flawless, smooth coatings. The particles are preferably located on the surface of the respective coating.

FIG. 1 shows a TEM image of a vertical section produced by a paint from a paint formulation according to Example 4. The accumulation of the particles on the paint surface is clearly visible.

The gloss of the coatings is determined with a gloss meter Micro gloss 20 ° from Byk and is in all paint formulation between 159 and 164 gloss units. The scratch resistance of the cured coating films produced in this way is determined using a scouring tester according to Peter-Dahn. For this, a scouring fleece Scotch Brite® 2297 with an area of 45 x 45 mm and a weight of 500 g is weighted. With this, the paint samples are scratched with a total of 40 strokes. Both before and after completion of the scratching tests, the gloss of the respective coating is measured with a gloss meter Micro gloss 20 ° from Byk. As a measure of the scratch resistance of the respective coating, the loss in gloss was determined in comparison with the starting value:

Table 2: Loss loss in the scratch test according to Peter-Dahn * not according to the invention

The results show that even the smallest contents of the particles (P) lead to a significant increase in the scratch resistance of the corresponding coating. This is a direct consequence of the accumulation of the particles on the paint surface, since even small particle contents are sufficient to achieve a high superficial particle density.

Claims

claims

1. Coatings (B) made from

Coating formulations (B1) which contain a) 20-90% by weight, based on the solids content, of a coating resin (L) having reactive groups, b) 0-90% by weight, based on the solids content, of a paint curing agent (H) which has reactive functions with which it can react with the reactive groups of the coating resin (L) during paint curing, c) 0.05-15% by weight, based on the solids content, of particles (P) and (d) 0 - 90 wt .-%, based on the total coating formulation (Bl), of a solvent or a solvent mixture, wherein a) the cured coating (B) aa) on its surface or ab) in the near-surface layers, the measured from the surface 1000 nm thick or ac) both at its surface and in the near-surface

Layers which, measured from the surface, are 1000 nm thick have a higher concentration of the particles (P) than in their interior, and in which b) the particles (P) are obtainable by reaction of colloidal metal or silica sols (P1) With

Organosilanes (A) consisting of the general formula (I) and (ID

(R ¹ O) ₃ _n (R ² ) _n Si-AX (I)

wherein R ^{1 is} hydrogen, alkyl, cycloalkyl or aryl radicals each with

1 to 6 C atoms, wherein the carbon chain may be interrupted by non-adjacent oxygen, sulfur or NR ^ groups,

R ^{2 is} alkyl, cycloalkyl, aryl or arylalkyl radicals each with

1 to 12 carbon atoms, wherein the carbon chain may be interrupted by non-adjacent oxygen, sulfur or NR ^ groups, R 3 is hydrogen, alkyl, cycloalkyl, aryl, arylalkyl,

Aminoalkyl or aspartate ester residues,

R 1 is hydrogen or any organic radical,

A is a divalent, optionally substituted alkyl,

Cycloalkyl or aryl radical having 1-10 carbon atoms, optionally substituted by oxygen, sulfur or NR ^

X may be an organic function, which is a chemical during lacquer curing

Reaction with functions of the paint resin (L) and / or the

Paint hardener (H) can enter, Y an organo function, which - optionally after the cleavage of the Si-Y bond - in the paint curing a chemical

Reaction with functions of the paint resin (L) or the

2. Coatings (B) made from

Coating formulations (B1) which contain a) 30-80% by weight, based on the solids content, of

Lackharzes (L), b) 5-60 wt .-%, based on the solids content, of Lackhärters (H), c) 0.1 to 12 wt .-%, based on the solids content of particles (P) and d) 0 to 70 wt .-%, based on the total coating formulation (Bl), a Solvent or one

Solvent mixture included.

3. Coatings (B) according to claim 1 and 2, wherein groups RA in the organosilanes (A) are methyl or ethyl radicals.

4. Coatings (B) according to claim 1 to 3, wherein groups X in the organosilanes (A) of the general formula (I) a

Hydroxyl or thiol, a group of the formula NHR ^, a heterocyclic ring containing an NH function or an epoxide ring, wherein R ^{5 has} the meanings of R ³ according to claim 1.

5. Coatings (B) according to Claims 1 to 3, in which the groups Y in the organosilanes (A) of the general formula (II) are a function which, after the cleavage of the Si-Y bond, has a hydroxyl group. or thiol function or a group of formula NHR ^ according to claim 5.

6. Coatings (B) according to claim 1 to 5, in which organosilanes (A) are used which correspond to the general formulas (III) or (IIIa)

(R ¹ O) _(III)

wherein B represents oxygen, sulfur, carbonyl, ester, amide or NR ^ group,

R ^{6 has} the meanings of R ³ , x can assume the values of 0 to 10 and the remaining variables have the meanings given in the general formulas (I) and (II) according to claim 1.

7. Coatings (B) according to claim 1 to 6, wherein the coating resins (L) consist of hydroxyl-containing polyacrylates or polyesters.

8. Coatings (B) according to claim 1 to 7, wherein the paint curing agent (H) contains free or protected isocyanate groups.

9. Use of the coatings (B) according to claim 1 to 8 as paints.

10. coating formulations (Bl) according to claim 1 to 8, which can be processed to the coatings of the invention (B).