EP1922370A2

EP1922370A2 - Coating materials containing silane-modified nanoparticles

Info

Publication number: EP1922370A2
Application number: EP06776871A
Authority: EP
Inventors: Norbert RÖSCH; Ernst Krendlinger; Anja Heinze; Karl Zeisberger
Original assignee: Clariant International Ltd
Current assignee: Clariant Finance BVI Ltd
Priority date: 2005-08-18
Filing date: 2006-08-16
Publication date: 2008-05-21
Also published as: WO2007020062A2; DE102005039436B4; CN101268156B; WO2007020062A3; CN101273099B; CN101273100A; CN101273099A; CN101268156A; JP2009504856A; DE102005039436A1; US20100006005A1

Abstract

The invention relates to coating materials containing silane-modified nanoparticles, an organic binder and possibly additives, wherein said coating materials contain silane-modified nanoparticles which are obtainable by disaggregating agglomerates containing said particles in the presence of an organic solvent and by simultaneously or afterwardly carrying out a silane treatment. The thus silane-modified nanoparticles provide the coating materials and coatings with an improved scratch resistance.

Description

Coating compositions containing silane-modified nanoparticles

Nanoparticles containing coating compositions are known, wherein the nanoparticles are prepared by sol-gel technique by hydrolytic (co) condensation of tetraethoxysilane (TEOS) with other metal alkoxides in the absence of organic and / or inorganic binders. From DE 199 24 644 it is known that the sol-gel synthesis can also be carried out in the medium. Radiation-curing formulations are preferably used. However, all materials produced by sol-gel process are characterized by low solids contents of inorganic and organic substance, by increased amounts of the condensation product (usually alcohols), by the presence of water and by limited storage stability.

Progress is made by the high-temperature-resistant, reactive metal oxide particles produced by hydrolytic condensation of metal alkoxides on the surface of nanoscale inorganic particles in the presence of reactive binders. The temperature resistance of the reacted formulations is achieved by the heterogeneous copolymerization of reactive groups of the medium with similar reactive groups of the binder. The disadvantage here is the incompleteness of the heterogeneous copolymerization, in which not all reactive groups on the surface of the particles enter the copolymerization. Reason are mainly steric hindrance. However, it is known that the unreacted groups lead to undesired secondary reactions, which can cause discoloration, embrittlement or premature degradation. This is especially true for high temperature applications. The process described in DE 198 46 660 also leads to non-storage-stable systems due to the acidic medium in the presence of the condensation product (usually alcohols). Also known are nanoscale surface-modified particles (Degussa Aerosil® R 7200), which are formed by condensation of metal oxides with silanes in the absence of a binder and thus in the absence of strong shear forces, as they act in viscous media at stirring speeds of> 10 m / s. For this reason, these aerosils have larger particles than the raw materials used, their opacity is markedly higher and their effectiveness is less than the effect of the particles described in WO 00/22052 and the paints prepared therefrom.

The object of the invention is to eliminate the disadvantages of the prior art and to provide storage and property stable coating compositions containing specially prepared nanoscale inorganic particles

The invention relates to coating compositions comprising silane-modified nanoparticles and an organic binder and optionally additives, characterized in that the coating compositions containing such silane-modified nanoparticles by deagglomeration of nanoparticles containing agglomerates in the presence of an organic solvent and simultaneous or subsequent treatment with a Silane can be obtained.

Preferred nanoparticles which are used according to the invention are particles having an average particle size in the range from 1 nm to 200 nm, preferably 1 to 100 nm, and consist of oxides of elements of main group 3, in particular aluminum.

These nanoparticles are made by deagglomeration of larger agglomerates containing or consisting of these nanoparticles in the presence of an organic solvent and simultaneous or subsequent treatment with a silane. Such agglomerates are known per se and can be prepared, for example, by the methods described below: By chemical syntheses, which are usually precipitation reactions, (hydroxide precipitation, hydrolysis of organometallic compounds) followed by calcination. Crystallization seeds are often added to reduce the transition temperature to α-alumina. The sols thus obtained are dried and thereby converted into a gel. The further calcination then takes place at temperatures between 350 ⁰ C and 65O ⁰ C. Must be then annealed at temperatures of about 1000 ⁰ C for the conversion to α-Al ₂ θ. ₃ The processes are described in detail in DE 199 22 492.

Another way to get nano-materials is the aerosol process. The desired molecules are obtained from chemical reactions of a Precursorgases or by rapid cooling of a supersaturated gas. The formation of the particles occurs either through collision or the constant equilibrium evaporation and condensation of molecular clusters. The newly formed particles grow by further collision with product molecules (condensation) and / or particles (coagulation). If the coagulation rate is greater than that of the new growth or growth, agglomerates of spherical primary particles are formed.

Flame reactors are based on this principle

Manufacturing variant dar. Nanoparticles are formed here by the decomposition of Precursormolekülen in the flame at 1500 ⁰ C - 2500 ⁰ C. As examples, the oxidations of TiCU; SiCl and Si2θ (CH ₃₎ ₆ 0 ₂ flames mentioned in methane / which lead to TiO ₂ and SiO ₂ particles. When using AICI3 so far only the corresponding clay could be produced. Flame reactors are now used industrially for the synthesis of submicroparticles such as carbon black, pigment TiO ₂ , silica and alumina.

Small particles can also be formed from drops with the help of centrifugal force, compressed air, sound, ultrasound and other methods. The drops are then converted into powder by direct pyrolysis or by in situ reactions with other gases. As known methods, the spray and freeze drying should be mentioned. In spray pyrolysis, precursor drops are formed transported through a high temperature field (flame, oven), resulting in rapid evaporation of the volatile component or initiating the decomposition reaction to the desired product. The desired particles are collected in filters. As an example, the production of BaTiO ₃ from an aqueous solution of barium acetate and titanium lactate can be mentioned here.

Grinding can also be used to crush corundum and thereby produce crystallites in the nano range. The best grinding results can be achieved with stirred ball mills in a wet grinding. In this case, grinding beads must be used from a material that has a greater hardness than corundum.

Another way to produce corundum at low temperature is the conversion of aluminum chlorohydrate. This is also added to this with seed preferably fines or hematite. To avoid crystal growth, the samples must be calcined at temperatures around 700 ⁰ C to a maximum of 900 ⁰ C. The duration of the calcination is described here with at least four hours. Recently, however, it has been found that in this process, calcination over a period of 0.5 to 10 minutes is quite sufficient to produce nanocrystalline corundum. The method which is preferred in the context of the present invention has been described in detail in Ber. DKG 74 (1997) no. 11/12, p. 719-722.

Specifically, in this preferred mode of nanocorundization, the procedure is as follows:

The starting point is aluminum chlorohydrate, which has the formula Al ₂ (OH) _x Cl _y , where x is a number from 2.5 to 5.5 and y is a number from 3.5 to 0.5 and the sum of x and y is always 6 amounts to. This aluminum chlorohydrate is mixed with crystallization seeds as an aqueous solution, then dried and then subjected to a thermal treatment (calcination). O

Preference is given to starting from 50% aqueous solutions, as they are commercially available. Such a solution is mixed with nuclei which promote the formation of the α-modification of Al ₂ O ₃ . In particular, such None effect a lowering of the temperature for the formation of α-modification in the subsequent thermal treatment. The germs are very finely disperse corundum, diaspore or hematite. Preference is given to taking very finely divided α-A ^ Oa nuclei having a mean particle size of less than 0.1 microns. In general, 2 to 3 wt .-% of germs based on the resulting alumina from.

This starting solution may additionally contain oxide formers. Chlorides, oxychlorides and / or hydrochlorides of the elements of II. To V. main group and the subgroups, in particular the chlorides, oxychlorides and / or hydrochlorides of the elements Ca, Mg, Y, Ti, Zr, Cr, Fe are especially suitable for this purpose , Co and Si.

This suspension of aluminum chlorohydrate, germs and optionally oxide formers is then evaporated to dryness and subjected to a thermal treatment (calcination). This calcination takes place in suitable devices, for example in push-through, chamber, pipe,

Rotary kiln or microwave ovens or in a fluidized bed reactor. According to a variant of the process according to the invention, it is also possible to inject the aqueous suspension of aluminum chlorohydrate and germs directly into the calcining apparatus without prior removal of the water.

The temperature for the calcination should not exceed 1100 ⁰ C. The lower temperature limit depends on the desired yield of nanocrystalline corundum, on the desired residual chlorine content and on the content of germs. The corundum formation starts at about 500 ⁰ C, but to keep the chlorine content low and the yield of nanocrystalline corundum high, but you will work preferably at 700 to 1100 ⁰ C, in particular at 1000 to 1100 ° C. It has been found that for calcination in general 0.5 to 30 minutes, preferably 0.5 to 10, in particular 0.5 to 5 minutes are sufficient. Already after this short time, a sufficient yield of nanocrystalline corundum can be achieved under the conditions given above for the preferred temperatures. However, one can also according to the information in Ber. DKG 74 (1997) no. 11/12, p. 722 for 4 hours at 700 ⁰ C or calcined for 8 hours at 500 ⁰ C. During calcination, agglomerates of nanocrystalline corundum accumulate in the form of nearly spherical nanoparticles.

The nanoparticles must be released from these agglomerates containing or entirely consisting of the desired nanoparticles in the form of crystallites. This is preferably done by grinding or by treatment with ultrasound. There are two possibilities for the modification according to the invention of these nanoparticles with silanes. According to the first variant, deagglomeration can be carried out in the presence of the silane, for example by adding the silane to the mill during milling. A second possibility consists of first destroying the agglomerates of the nanocorundum and then treating the nanoparticles, preferably in the form of a suspension in an organic solvent, with the silane.

Suitable silanes are preferably the following types in question:

a) R [-Si (FTFO-0-] _n Si (FTFR) -R ^'' or cyclo - [- Si (R ^'R ^") -O-] _r Si (R ^Λ ^R") -O-

embedded image in which

R, R ', R "\ R'" - identical or different from each other, an alkyl radical having 1-18 C atoms or a phenyl radical or an alkylphenyl or a phenylalkyl radical having 6 - 18 C atoms or a radical of the general formula - ( C _m H _2m -O) _p - CqH ₂ q ₊ i or a radical of the general formula -C ₃ H _2s Y or a radical of the general formula -XZ _t- i, n is an integer meaning 1 ≤ n <1000, preferably 1 <n <100, m is an integer 0 ≤ m ≤ 12 and p is an integer 0 <p ≤ 60 and q is an integer 0 ≤ q.≤40 and r is an integer 2 <r ≦ 10 and s is an integer 0 ≦ s ≦ 18 and Y is a reactive group, for example α, β-ethylenically unsaturated groups, such as (meth) acryloyl, vinyl or allyl groups, amino, Amido, ureido,

Hydroxyl, epoxy, isocyanato, mercapto, sulfonyl, phosphonyl, trialkoxysilyl, alkyldialkoxysilyl, dialkylmonoalkoxysilyl, anhydride and / or carboxyl groups, imido, imino, sulfite, sulfate, sulfonate, phosphine -

Phosphite, phosphate, phosphonate and X is a t-functional oligomer with t an integer 2 ≤ t ≤ 8 and Z in turn a radical

R [-Si (R ^{^'R'>} O-] "Si (R ^{^'R")} -R ^{^} or cyclo - [- Si ^(R' R ^") -O-] _r Si (R ^'R") - O -

means as defined above.

The t-functional oligomer X is preferably selected from: oligoether, oligoester, oligoamide, oligourethane, oligourea, oligoolefin, oligovinyl halide, oligovinylidenedihalogenide, oligoimine, oligovinyl alcohol, esters, acetal or ethers of oligovinyl alcohol, cooligomers of maleic anhydride, oligomers of (meth) acrylic acid , Oligomers of (meth) acrylic esters,

Oligomers of (meth) acrylic acid amides, oligomers of (meth) acrylic acid imides, oligomers of (meth) acrylonitrile, particularly preferably oligoethers, oligoesters, oligourethanes.

Examples of radicals of oligoethers are compounds of the type - (C _a H _2a -O) _b - C _a H _2a - or O- (C _a H2a-O) b-CaH ₂ aO with 2 <a <12 and 1 ≤ b <60, for example a diethylene glycol, triethylene glycol or tetraethylene glycol radical, a dipropylene glycol, tripropylene glycol, tetrapropylene glycol radical, a Dibutylene glycol, tributylene glycol or tetrabutylene glycol residue. Examples of residues of oligoesters are compounds of the type -C _b H _2b - (O (CO) C _a H _2a - (CO) O- C _b H _2b -) c- or -OC _b H _2b - (O (CO ) C ₃ H ₂₃ - (CO) OC _b H _2b -) _c -O- with a and b different or equal to 3 <a <12, 3 <b <12 and 1 <c <30, eg an oligoester of hexanediol and adipic acid.

b) organosilanes of the type (RO) ₃ Si (CH ₂ ) _m -R 'R = alkyl, such as methyl, ethyl, propyl, m = 0.1-20 R ¹ = methyl, phenyl,

-C ₄ F ₉ ; OCF ₂ -CHF-CF ₃ , -C ₆ F ₁₃ , -O-CF ₂ -CHF ₂

-NH ₂ , -N ₃ , -SCN, -CH = CH ₂ , -NH-CH ₂ -CH ₂ -NH ₂ ,

-N- (CH ₂ -CH ₂ -NH ₂ ) ₂

-OCO (CH ₃ ) C = CH ₂ -OCH ₂ -CH (O) CH ₂

-NH-CO-N-CO- (CH ₂ ) ₅

-NH-COO-CH ₃ , -NH-COO-CH ₂ -CH ₃ , -NH- (CH ₂ ) ₃ Si (OR) ₃

-S _x - (CH ₂ ) ₃ ) Si (OR) ₃

-SH-NR ¹ R ¹¹ R ¹ "(R ¹ = alkyl, phenyl, R" = alkyl, phenyl, R ¹ "= H, alkyl, phenyl,

benzyl,

C ₂ H ₄ NR ¹¹¹¹ R ¹ " ¹¹ with R""= A, alkyl and R = H, alkyl).

Examples of silanes of the type defined above are, for example, hexamethyldisiloxane, octamethyltrisiloxane, other homologous and isomeric compounds of the series Si _n O _n-1 (CH 2) _{2n + 2} , where n is an integer 2 <n <1000, eg polydimethylsiloxane 200® fluid

(20 cSt).

Hexamethylcyclotrisiloxane, octamethylcyclo tetrasiloxane, other homologous and isomeric compounds of the series (Si-O) r (CH ₃ ) _2r , where r is an integer 3 ≤ r ≤ 12, Dihydroxytetramethydisiloxane, dihydroxyhexamethyltrisiloxane,

Dihydroxyoctamethyltetrasiloxane, other homologous and isomeric compounds of the series

HO - [(Si-O) _n (CH ₃₎ ₂ N] -Si (CH ₃₎ ₂ -OH, or HO - [(Si-O) _n (CH ₃₎ ₂ n] - [Si-O) _m (C ₆ H ₅ ) ₂ m] -Si (CH ₃ ) ₂ -OH, where m is an integer 2 ≦ m <1000, preferred are the α, ω-dihydroxypolysiloxanes, for example polydimethylsiloxane

(OH end groups, 90-150 cSt) or polydimethylsiloxane-co-diphenylsiloxane,

(Dihydroxy end groups, 60 cST).

Dihydrohexamethytrisiloxane, Dihydrooctamethyltetrasiloxan other homologous and isomeric compounds of the series

H - [(Si-O) _n (CH ₃ ) ₂ n] -Si (CH ₃ ) ₂ -H wherein, n is an integer 2 ≦ n <1000, preferably the α, ω-dihydropolysiloxanes, eg polydimethylsiloxane ( Hydride end groups, M _n = 580).

Di (hydroxypropyl) hexamethyltrisiloxane, dihydroxypropyl) octamethyltetrasiloxane other homologous and isomeric compounds of the series

HO- (CH ₂ ) u [(Si-O) n (CH ₃ ) ₂ n] -Si (CH ₃ ) ₂ (CH ₂ ) u -OH are preferably the α, ω-dicarbinol polysiloxanes with 3 ≦ u ≦ 18, 3 <n ≤ 1000 or their polyether-modified successor compounds based on the ethylene oxide (EO) and

Propylene oxide (PO) as homo- or mixed polymer HO- (EO / PO) _v - (CH ₂ ) _u [(Si)

O) _t (CH ₃ ) _2t ] -Si (CH ₃ ) ₂ (CH ₂ ) _u - (EO / PO) v-OH are preferred α, ω-di (carbinolpolyether) polysiloxanes with 3 <n <1000, 3 <u <18, 1 ≤ v <50.

Instead of .alpha.,. Omega.-OH groups, the corresponding difunctional compounds are also used with epoxy, isocyanato, vinyl, allyl and di (meth) acryloyl groups, e.g. Vinyl-terminated polydimethylsiloxane (850-1150 cSt) or TEGORAD 2500 from Tego Chemie Service.

Also suitable are the esterification products of ethoxylated / propoxylated trisiloxanes and higher siloxanes with acrylic acid copolymers and / or maleic acid copolymers as modifying compound, eg BYK Silclean 3700 from Byk Chemie or TEGO® Protect 5001 from Tego Chemie Service GmbH.

Instead of α, ω-OH groups, the corresponding difunctional compounds are also used with -NHR "" with R "" = H or alkyl, e.g. the well-known aminosilicone oils from Wacker, Dow Corning, Bayer, Rhodia, etc., which carry randomly distributed (cyclo) -alkylamino groups or (cyclo) -alkylimino groups on their polymer chain on the polysiloxane chain.

Organosilanes of type (RO) ₃ Si (C _n H 2n + i) and (RO) ₃ Si (CnH ₂ n + i), wherein R is an alkyl such as methyl, ethyl, n-propyl, i-propyl -, butyl, n 1 to 20.

Organosilanes of the type R'x (RO) y Si (C _n H 2n + i) and (RO) ₃ Si (C _n H _2n +!), Wherein R is an alkyl such as methyl, ethyl, n-propyl, i-propyl, butyl,

R 'is an alkyl, e.g. Methyl, ethyl, n-propyl, i-propyl, butyl,

R ^{1 is} a cycloalkyl n is an integer from 1 to 20 x + y 3 x 1 or 2 y 1 or 2.

Organosilanes of the type (RO) ₃ Si (CH ₂ ) (Ti-R ¹ , wherein R is an alkyl such as methyl, ethyl, propyl, m is a number between 0.1 to 20

R ^{1 is} methyl, phenyl, -C ₄ F ₉ ; OCF ₂ -CHF-CF ₃ , -C ₆ Fi ₃ , -O-CF ₂ -CHF ₂ , -NH ₂ , -N ₃ , -SCN, -CH = CH ₂ , -NH-CH ₂ -CH ₂ -NH ₂ , -N- (CH ₂ -CH ₂ -NH ₂ J ₂ , -OOC (CH ₃ ) C = CH ₂ , -OCH ₂ -CH (O) CH ₂ , -NH-CO-N-CO- (CH ₂ ) ₅ -NH-COO-CH ₃ , -NH-COO-CH ₂ -CH ₃ , -NH- (CH ₂ ) ₃ Si (OR) ₃ , -S _x - (CH ₂ ) ₃ ) Si (OR ) _3, -SH-NR ¹ R ¹¹ R ¹ "(R ¹ = alkyl, phenyl, R" = alkyl, phenyl, R ¹ "= H, alkyl, phenyl,

Benzyl, C ₂ H ₄ NR ¹¹¹¹ R " ¹ " with R ¹¹¹¹ = A, alkyl and R ¹ "" = H, alkyl).

Preferred silanes are the compounds listed below: Triethoxysilane, octadecyltimethoxysilane,

3- (trimethoxysilyl) -propylmethacrylate, 3- (trimethoxysilyl) -propylacrylate, 3- (trimethoxysilyl) -methylmethacrylate, 3- (trimethoxysilyl) -methylacrylate, 3- (trimethoxysilyl) -ethylmethacrylate, 3- (trimethoxysilyl) -ethylacrylate, 3- (Trimethoxysilyl) pentyl methacrylates, 3- (trimethoxysilyl) pentyl acrylates, 3- (trimethoxysilyl) hexyl methacrylates, 3- (trimethoxysilyl) hexacrylates, 3- (trimethoxysilyl) butyl methacrylates, 3- (trimethoxysilyl) butyl acrylates, 3- (trimethoxysilyl ) -heptylmethacrylate, 3- (trimethoxysilyl) -heptylacrylate, 3- (trimethoxysilyl) -octylmethacrylate, 3- (trimethoxysilyl) -octylacrylate, Methyltrimethoxysilane, Methyltriethoxysilane, Propyltrimethoxisilane, Propyltriethoxisilane, Isobutyltrimethoxisilane, Isobutyltriethoxysilane, Octyltrimetoxysilane, Octyltriethoxysilane, hexadecyltrimethoxysilane, Phenyltrimethoxysilane, Phenyltriehoxysilane, tridecafluoro-1, 1, 2,2-tetrahydrooctyltriethoxysilane, tetramethoxysilane, Teraethoxysilan, Oligomeric tetraethoxysilane (DYNASIL ^® 40 F Degussa), tetra-n-propoxysilane,

3-Glycidyloxypopyltrimethoxysilan, 3-Glycidyloxypropyltriethoxysilane, 3-Methacryloxylpropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilanes, 3-Mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 2-aminoethyl-3- aminopropyltrimethoxysilane, Triaminofunctional propyltrimethoxysilanes (DYNASYLAN ^® triamino Fa. Degussa), N- ( n-butyl) -3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane.

These silanes are preferably added in molar ratios of corundum to silane from 1: 1 to 10: 1. The amount of organic solvent in the deagglomeration is generally 80 to 90 wt .-%, based on the total amount of corundum and solvent. As a solvent, in principle, all organic solvents can be used. Preference is given to CrC ₄ -alcohols, in particular methanol, ethanol or isopropanol, and also acetone or tetrahydrofuran. The deagglomeration by grinding and simultaneous modification with the silane is preferably carried out at temperatures of 20 ° to 150 ⁰ C, more preferably at 20 ⁰ C to 90 ⁰ C.

If deagglomeration is carried out by grinding, the suspension is subsequently separated from the grinding beads.

After deagglomeration, the suspension can be heated to complete the reaction for up to 30 hours. Finally, the solvent is distilled off and the remaining residue is dried.

It is also possible to suspend the corundum in the corresponding solvents and to carry out the reaction with the silane after deagglomeration in a further step.

The coating compositions of the invention, which are ceramic coatings, anodized coatings, but preferably lacquers, also contain customary and known binders, for example those described below:

Paint binders for one- and multi-component polymer systems, i. In the case of the multicomponent polymer systems, both the resin and the hardener may be filled with the particles described under a) and b) and include the components mentioned above from the paint technique:

mono- to polyfunctional acrylates, for example butyl acrylate, ethylhexyl acrylate, norbornyl acrylate, butanediol diacrylate, hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane triethoxytriacrylate, pentaerythritol tetraethoxytriacrylate, pentaerythritol tetraethoxytetraacrylate, polyether acrylate, polyether acrylate, Polyurethane acrylates, for example Craynor ^® CN 925, CN 981 of Cray Valley Resins GmbH, Ebecryl ^® EB 1290 from UCB GmbH, Laromer® 8987 from BASF AG, Photomer® 6019 or Photomer ^® 6010 the company. Cognis, polyester, for example Craynor ^® CN 292 Cray Valley resins GmbH, Laromer® ^® LR 8800 from BASF AG, Ebecryl ^® EB 800 UCB GmbH, Photomer ^® 5429 F and Photomer ^® 5960 F from. Cognis,

Epoxy acrylates, for example Laromer® ^® EA 81 from BASF AG, Ebecryl ^® EB 604 UCB GmbH, Craynor ^® CN104D80 of Cray Valley Resins GmbH,

dendritic polyester / ether acrylates from the company Perstorp Specialty Chemicals AG or Bayer AG,

Polyurethane polymers and their precursors in the form of polyisocyanates, polyols, polyurethane prepolymers, as a capped prepolymer and as reacted polyurethanes in the form of a melt or solution. In detail these are:

Polyols in the form of polyethers, for example polyethylene glycol 400, Voranol ^® P 400 and

Voranol ^® CP 3055 of Dow Chemicals, polyesters, such Lupraphen ^® 8107, Lupraphen ^® 8109 the Elastorgan ^® GmbH, Desmophen ^® 670, Desmophen ^® 1300 from Bayer AG, Oxyester ^® T 1136 from Degussa AG, alkyd resins, for example WORLÉEKYD ^® C

625 of Worlee Chemie GmbH,

Polycarbonates, such as Desmophen ^® C 200, hydroxyl-containing polyacrylates, for example,

Desmophen ^® A 365 from Bayer AG, polyisocyanates such as Desmodur ^® N 3300, Desmodur ^® VL, Desmodur ^® Z 4470,

Desmodur ^® IL or Desmodur ^® L 75 from Bayer AG, vestanate ^® T 1890 L of

Degussa AG, Rodocoat ^® WT 2102 Rhodia Syntech GmbH,

Polyurethane prepolymers, such as Desmodur ^® E 4280 of Bayer AG, vestanate ^® EP-U 423 from Degussa AG,

PMMA and further poly (meth) alkyl acrylates, for example Plexisol ^® P 550 and Degalan LP 50/01 ^® from Degussa AG, Polyvinyl butyral and other Polyvinylacrylate such Mowital® ^® B 30 HH Clariant GmbH,

Polyvinyl acetate and its copolymers, eg Vinnapas® ^® B 100/20 VLE Wacker-Chemie GmbH.

For all polymers, both the aliphatic and the aromatic variants are expressly included. The binder may also be selected to be identical to the silane used for functionalization.

The binders preferably have a molecular weight of 100 to 800 g / mol. The content of binder in the entire coating composition is preferably 80 to 99, in particular 90 to 99 wt .-%.

The coating compositions according to the invention may also contain other additives, as are customary in paint technology, for example reactive diluents, solvents and co-solvents, waxes, matting agents, lubricants, defoamers, deaerators, leveling agents, thixotropic agents, thickeners, inorganic and organic pigments, fillers, adhesion promoters , Corrosion inhibitors, anticorrosion pigments, UV stabilizers, HALS compounds, free-radical scavengers, antistatic agents, wetting and dispersing agents and / or the catalysts, cocatalysts, initiators, radical formers, photoinitiators, photosensitizers, etc., which are required depending on the type of curing. Polyethylene glycol is also used as further additives and other water retention agents, PE waxes, PTFE waxes, PP waxes, amide waxes, FT paraffins, montan waxes, grafted waxes, natural waxes, macro and microcrystalline paraffins, polar polyolefin waxes, sorbitan esters, polyamides, polyolefins, PTFE, N wetting agent or silicates in question.

The subject according to the invention is intended to be explained in more detail with reference to the following examples, without restricting the possible variety. Example 1 :

A 50% aqueous solution of aluminum chlorohydrate was treated with 2% crystallization nuclei of a suspension of fine corundum. After the solution was homogenized by stirring, the drying was carried out in a rotary evaporator. The solid aluminum chlorohydrate was crushed in a mortar to form a coarse powder.

The powder was calcined in a muffle furnace at 1050 ^° C. The contact time in the hot zone was a maximum of 5 min. A white powder was obtained whose grain distribution corresponded to the feed material.

An X-ray structure analysis showed that it is phase-pure α-alumina. The images of the SEM image taken (scanning electron microscope) showed crystallites in the range 10-100 nm. The residual chlorine content was only a few ppm. To obtain the nanoparticles, 150 g of this corundum powder were suspended in 110 g of isopropanol and ground for 3 hours in a vertical stirred ball mill. The solvent was then distilled off and the residual moist residue dried at 100 ⁰ C for 20 h.

Example 2:

150 g of corundum powder with a grain size in the range 10 - 50 microns, consisting of crystallites <100 nm, was suspended in 110 g of isopropanol. 40 g of trimethoxy-octylsilane were added to the suspension and fed to a vertical stirred ball mill from Netzsch (type PE 075). The grinding beads used consisted of zirconium oxide (stabilized with yttrium) and had a size of 0.3-0.5 mm. After three hours, the suspension was separated from the milling beads and boiled under reflux for a further 4 h. Subsequently, the solvent was distilled off and the residual moist residue in a drying oven at 110 ⁰ C dried for a further 20 h.

The images of the SEM image (scanning electron microscope) showed the presence of crystallites in the range 10-100 nm. Example 3:

150 g of corundum powder with a grain size in the range 50-200 μm, consisting of crystallites <100 nm, were suspended in 110 g of isopropanol. To the suspension was added 40 g of trimethoxy-octylsilane and fed to a horizontal stirred ball mill. The grinding beads used consisted of zirconium oxide (stabilized with yttrium) and had a size of 0.5-1.0 mm. After six hours, the suspension was separated from the milling beads and boiled under reflux for a further 4 h. The solvent was then distilled off and the residual moist residue in a drying oven at 11O ⁰ C dried for a further 20 h.

The images of the SEM image (scanning electron microscope) showed the presence of crystallites in the range 10-100 nm.

Example 4:

50 g of corundum powder with a grain size in the range 10 to 50 μm, consisting of crystallites <100 nm, were suspended in 180 g of isopropanol. 20 g of trimethoxy-octadecylsilane were added to the suspension and fed to a vertical stirred ball mill from Netzsch (type PE 075). The grinding beads used consisted of zirconium oxide (stabilized with yttrium) and had a size of 0.3-0.5 mm. After three hours, the suspension was separated from the milling beads and boiled under reflux for a further 4 h. The solvent was then distilled off and the residual moist residue in a drying oven at 11O ⁰ C dried for a further 20 h.

Example 5:

50 g of corundum powder with a grain size in the range 50-200 μm, consisting of crystallites <100 nm, were suspended in 180 g of isopropanol. 20 g of trimethoxy-octadecylsilane were added to the suspension and fed to a horizontal stirred ball mill. The grinding beads used consisted of zirconium oxide (stabilized with yttrium) and had a size of 0.5-1.0 mm. After six hours, the suspension was separated from the milling beads and boiled under reflux for a further 4 h. Subsequently, the Solvent distilled off and the residual moist residue in a drying oven at 110 ⁰ C dried for a further 20 h.

Example 6: 40 g of corundum powder with a particle size in the range 10-50 μm, consisting of crystallites <100 nm, were suspended in 160 g of methanol. 10 g of 3- (trimethoxysilyl) propyl methacrylate were added to the suspension and fed to a vertical stirred ball mill from Netzsch (type PE 075). The grinding beads used consisted of zirconium oxide (stabilized with yttrium) and had a size of 0.3-0.5 mm. After three hours, the suspension was separated from the milling beads and boiled under reflux for a further 4 h. The solvent was then distilled off and the remaining moist residue in a drying oven at 8O ⁰ C dried for a further 20 h.

Example 7:

40 g of corundum powder with a grain size in the range 50-100 μm, consisting of crystallites <100 nm, were suspended in 160 g of methanol. To the suspension was added 10 g of 3- (trimethoxysilyl) propyl methacrylate and fed to a horizontal stirred ball mill. The grinding beads used consisted of zirconium oxide (stabilized with yttrium) and had a size of 0.5-1.0 mm. After six hours, the suspension was separated from the milling beads and boiled under reflux for a further 4 h. The solvent was then distilled off and the residual moist residue in a drying oven at 80 ⁰ C dried for a further 20 h.

applications

Non-surface-modified nanocorundum from Example 1 and the various surface-modified corundum samples from Examples 2-7 were tested for abrasion resistance, gloss and scratch resistance in various coating systems. The tests were carried out in an aqueous acrylic lacquer system, a 2-component polyurethane lacquer system and a 100% UV lacquer system. I. Aqueous acrylic paint system

shine

Of the paint films on the glass plates, the gloss was determined by means of the micro-gloss from BYK-Gardner at an angle of 60 °.

Pencil hardness The hardness of the paint films on the glass plates was determined by means of the pencil hardness according to Wolff-Wilborn according to the scale below.

soft 6B 5B 4B 3B 2B B HB

H 2H 3H 4H 5H 6H 7H 8H 9H hard

Tabertest - abrasion

The paint samples were sprayed onto special glass plates using an air gun. After several turns, the Taber Abraser was used to measure the turbidity / haze with the Haze-Gard Plus and the haze change was calculated.

2-component polyurethane varnish

The samples from Examples 2-7 were dispersed in the first component of a 2-component PUR coating system.

abrasion

The paint samples were sprayed onto special glass plates using an air gun. With the Taber Abraser, the weights were determined after several revolutions and thus the abrasion was calculated.

Nanobyk is a dispersion of surface-modified nanoaluminum in methoxypropyl acetate as a solvent to improve scratch resistance.

shine

Of the paint films on the glass plates, the gloss was determined by means of the micro-gloss from BYK-Gardner at an angle of 60 °. (Wet film thickness 60 μm)

Pencil hardness The hardness of the paint films on the glass plates was determined by means of the pencil hardness according to Wolff-Wilborn.

III. UV varnish

The samples from Examples 1 to 7 were dispersed in the first component of a 2-component PUR coating system.

abrasion

shine

pencil hardness

From the paint films on the glass plates, the hardness was determined by means of the pencil hardness according to Wolff-Wilborn.

Haze / haze of paint films

Haze-Gard Plus Haze-Gard Plus Haze-Gard Plus haze coating on the glass plates (wet film thickness 60 μm).

Claims

claims

1. Coating compositions comprising silane-modified nanoparticles and an organic binder and optionally additives, characterized in that the coating compositions contain such silane-modified nanoparticles obtained by deagglomeration of nanoparticle-containing agglomerates in the presence of an organic solvent and simultaneous or subsequent treatment with a silane become.

2. Coating compositions according to claim 1, characterized in that it is a lacquer.

3. Coating compositions according to claim 1, characterized in that they contain silane-modified nanoparticles which are obtained by deagglomeration of nanoparticle-containing agglomerates by grinding or the action of ultrasound.

4. Coating compositions according to claim 1, characterized in that they contain silane-modified nanoparticles obtained by deagglomeration of nanoparticle-containing agglomerates by grinding and simultaneous treatment with a silane.

5. Coating compositions according to claim 1, characterized in that they contain silane-modified nanoparticles which are obtained by deagglomeration of nanoparticle-containing agglomerates by grinding and simultaneous treatment with a lower alcohol.

6. Coating compositions according to claim 1, characterized in that they contain silane-modified nanoparticles obtained by deagglomeration of nanoparticle-containing agglomerates by grinding and simultaneous

Treatment with a silane in a lower alcohol at temperatures of 20 to 15O ⁰ C are obtained.