EP1163299A2

EP1163299A2 - Sol-gel coatings for single-layer or multi-layer varnishes

Info

Publication number: EP1163299A2
Application number: EP00920478A
Authority: EP
Inventors: Peter Betz; Wilfried Stubbe; Horst HINTZE-BRÜNING
Original assignee: BASF Coatings GmbH
Current assignee: BASF Coatings GmbH
Priority date: 1999-03-06
Filing date: 2000-03-06
Publication date: 2001-12-19
Also published as: WO2000053687A2; BR0008843A; DE19909877A1; AU4104100A; WO2000053687A3; JP2002538283A

Abstract

The invention relates to a sol-gel coating material containing (A) an acrylate copolymer solution containing at least one acrylate copolymer (A1); (B) a parent varnish which can be prepared by hydrolysis and condensation of at least one hydrolysable silane (B1) of the general formula (I) SiR4, in which the variable R = hydrolysable groups, hydroxy groups and non-hydrolysable groups, subject to the condition that there should be at least one, preferably two, hydrolysable groups; and (C) a sol which can be prepared by hydrolysis, condensation and complexing of at least one hydrolysable silane (B1) of the general formula (I) and at least one hydrolysable metal compound (C1) of the general formula (II) MRn, in which the variables and the index have the following meanings: M = aluminium, titanium or zirconium; R = hydrolysable groups, hydroxy groups and non-hydrolysable groups, subject to the condition that there should be at least one, preferably two, hydrolysable groups; and n = 3 or 4.

Description

Sol-gel coating for single-layer or multi-layer coatings

The present invention relates to a new sol-gel coating material for the production of sol-gel coatings on single-layer or multi-layer coatings. In particular, the present invention relates to a new process for the production of painted substrates, in particular painted automobile bodies, in which the substrates are first provided with a multi-layer coating, after which a sol-gel coating material is applied and cured.

Automobile bodies are mostly provided with a multi-layer paint system. Clear varnishes are often applied as the last coating layer. The usual and known one-component (1K), two-component (2K), and multi-component (3K, 4K) powder or powder slurry clearcoats or UV-curable clearcoats come into consideration.

One-component (IC), two-component (2K) or multicomponent (3K, 4K) clearcoats are described, for example, in the patents US-A-5,474,811, US-A-5,356,669, US-A-5,605,965, WO 94/10211, WO 94 / 10212, WO 94/10213, EP-A-0 594 068, EP-A-0 594 071, EP-A-0 594 142, EP-A-0 604 992, WO 94/22969, EP-A-0 596 460 or WO 92/22615.

Powder clearcoats are known, for example, from German patent specification DE-A-42 22 194 or the product information from BASF Lacke + Farben AG, "Powder coatings", 1990.

Powder slurry coatings are powder coatings in the form of aqueous dispersions. Such slurries are described, for example, in US Pat. No. 4,268,542 and German patent applications DE-A-195 18 392.4 and DE-A-196 13 547 and the unpublished German patent application DE-A-198 14471.7.

UV-curable clearcoats are known, for example, from the patents EP-A-0 540 884, EP-A-0 568 967 or US-A-4,675,234.

Each of these clear coats has its specific strengths and weaknesses. With these clear coats you get multi-layer coatings that meet the optical requirements. However, the scratch-resistant one-component (LC) clear coats are sometimes not sufficiently weather-resistant, whereas the weather-resistant two-component (2K) or multi-component (3K, 4K) clear coats are often not sufficiently scratch-resistant. Some one-component (LC) clear coats are scratch-resistant and weather-resistant, but in combination with frequently used water-based paints they have surface defects such as shrinking.

Powder clearcoats, powder slurry clearcoats and UV-curable clearcoats, on the other hand, have an incompletely satisfactory interlayer adhesion without the problems of scratch resistance or etch resistance being completely solved.

So-called sol-gel clearcoats based on siloxane-containing lacquer formulations have been developed more recently, which are obtained by hydrolysis and condensation of silane compounds. These lacquers, which are used as coating agents for coatings on plastics, are described, for example, in German patent specifications DE-A-43 03 570, 34 07 087, 40 11 045, 4025 215, 38 28 098, 40 20 316 or 41 22743.

Sol-gel clear coats give plastic substrates such as B. glasses or

Motorcycle heights have a very good scratch resistance. This scratch resistance is known from the well-known OEM (Original Equipment Manufacturing) clearcoats usually used in the initial painting of vehicles, not achieved. The automotive industry is now required to transfer this improved scratch resistance to the clearcoat layers used in the painting of automobiles.

However, the replacement of the OEM clearcoats or OEM powder slurry clearcoats usually used in automotive painting with sol-gel clearcoats is not possible without further ado because B. are too brittle or because when trying to adapt them to the OEM requirements, often only poor optical properties (appearance) are achieved. Above all, the sol-gel clearcoats are too expensive. The economically more favorable use of the sol-gel clearcoats as an additional coating layer over the previously used clearcoats or powder-slurry clearcoats results in adhesion problems between the clearcoat and the sol-gel layer, which occur in particular after stone chipping and when exposed to condensation.

These problems can be solved by only partially curing the clearcoat layer which is to be coated with the sol-gel clearcoat, so that the sol-gel coating can be chemically anchored to the clearcoat layer during the joint curing. However, this procedure promotes that in one and the same painting line the clearcoat layers on automobile bodies which are to be overcoated have to be cured at a different temperature than the clearcoat layers of the other automobile bodies which should not be overcoated. The use of different curing conditions in a painting line is a major disadvantage. This disadvantage is even more difficult because the second clear coat requires a long oven drying time to cure.

The object of the present invention is to provide a new sol-gel coating material which allows the advantageous ones To combine properties of the sol-gel coatings with the advantageous properties of the known single-layer or multi-layer coatings, in particular the multi-layer coatings for the automotive OEM painting, without the customary painting processes, in particular the wet-on-wet process in the automotive painting , must be deviated. In other words, the new sol-gel coating material should allow a scratch-resistant coating to be applied to finished, already cured paintwork in a short time, without causing adhesion problems.

Accordingly, the new sol-gel coating material has been found to contain

(A) an acrylate copolymer solution containing at least one

Acrylate copolymer (AI), obtainable by copolymerization of at least the following monomers:

al) at least one (meth) acrylic acid ester which is essentially free of acid groups,

a2) at least one ethylenically unsaturated monomer which carries at least one hydroxyl group per molecule and is essentially free of acid groups, and

a3) at least one at least one acid group, which can be converted into the corresponding acid anion group, per molecule-bearing ethylenically unsaturated monomer;

(B) a free base lacquer which can be prepared by hydrolysis and condensation of at least one hydrolyzable silane (B1) of the general formula I. SiR, (I),

where the variable R has the following meaning:

R = hydrolyzable groups, hydroxyl groups and non-hydrolyzable groups, with the proviso that at least one, preferably at least two, hydrolyzable group (s) is or are present;

and

(C) a sol which can be prepared by hydrolysis, condensation and complexation of at least one hydrolyzable silane (B1) of the general formula I and at least one hydrolyzable metal compound (Cl) of the general formula II

MR _n (ID-

where the variables and the index have the following meaning:

M = aluminum, titanium or zirconium,

R = hydrolyzable groups, hydroxyl groups and non-hydrolyzable groups, with the proviso that at least one, preferably at least two, hydrolyzable group (s) is or are present, and

n 3 or 4. The new sol-gel coating material is referred to below as “coating material according to the invention”.

In addition, the new process for the production of sol-gel coatings on single-layer or multi-layer coatings was carried out

(i) application of a single-layer or multi-layer coating on an optionally primed substrate,

(ii) application of a sol-gel coating material to the single-layer or multi-layer coating and

(iii) curing the sol-gel coating material,

found, which is characterized in that a coating material according to the invention is used here.

For the sake of brevity, the new process for the production of sol-gel coatings on single-layer or multi-layer coatings is referred to below as the “process according to the invention”.

Furthermore, new sol-gel coatings were found which can be produced from the coating materials according to the invention and are referred to below as “sol-gel coatings according to the invention”.

Last but not least, new substrates were found which have at least one sol-gel coating according to the invention and are referred to below as “substrates according to the invention”. In view of the prior art, it was surprising and unforeseeable for the person skilled in the art that the object on which the invention is based could be achieved with the aid of the coating material according to the invention and the method according to the invention. In particular, it was surprising that the coating material of the invention adheres to the finished, hardened paints without problems, without it being subjected to stone chips or after exposure to condensation, ie a ten-day exposure of the layers in an atmosphere of 40 ° C. and 100% relative atmospheric humidity , comes off or cracks. The optical properties of the coatings provided with the sol-gel coatings according to the invention also meet all the requirements.

The coating material of the invention is a siloxane-containing coating formulation which can be prepared by reacting hydrolyzable silicon compounds with water or water-releasing agents and which contains organic constituents to improve certain properties. A general description of such systems can be found, for example, in the article by Bruce M. Novak, "Hybrid Nanocomposite Materials-Between hiorganic Glasses and Organic Polymers", in Advanced Materials, 1993, 5, No. 6, pp. 422-433, or in the lecture by R. Kasemann, H. Schmidt, 15th International Conference, International Center for Coatings Technology, Paper 7, "Coatings for mechanical and chemical protection based on organic-inorganic sol-gel nanocomposites", 1993.

The basic reactions take place in a sol-gel process, in which tetraorthosilicates are optionally hydrolyzed and condensed in the presence of a co-solvent:

Hydrolysis: Si (OR) ₄ + H ₂ O → (RO) ₃ Si-OH + ROH Condensation:

-Si-OH + HO-Si- → -Si-O-Si- + H ₂ O -Si-OH + RO-Si- → -Si-O-Si- + ROH

where R can be an alkyl group such as methyl or ethyl. Tetramethyl orthosilicate (TMOS) or tetraethyl orthosilicate (TEOS) are often used. Acids, bases or fluoride ions are used to catalyze the reactions.

The coating material of the invention is accordingly a siloxane-containing structure which has been modified with organic constituents (Ormocer® = Organically Modified Ceramic).

The sol-gel coating according to the invention is produced by targeted hydrolysis and condensation of silicic acid esters and of metal alcoholates. It obtains special properties through the incorporation of organically modified silicic acid derivatives into the silicate network. They allow the construction of an organic polymer network in addition to the inorganic backbone if organic residues are preferably used with olefinically unsaturated groups and / or epoxy groups.

The modification can e.g. B. done in that a finished organic polymer is present during the hydrolysis and condensation of the starting products or in the sol.

The coating material according to the invention consists of the three essential components (A), (B) and (C).

Component (A) is an acrylate copolymer solution. It is preferably free from aromatic solvents. In the context of the present invention, the term “free from aromatic solvents” or “free from aromatics” here and below means that the content of aromatic solvents or aromatic compounds in a solution is <1% by weight, preferably <0.5% by weight. % and particularly preferably <0.2% by weight and in particular below the gas chromatographic detection limit.

The acrylate copolymer solution (A) to be used according to the invention contains at least one acrylate copolymer (AI) which, by copolymerizing the monomers (al), (a2) and (a3) mentioned below and optionally further monomers (a4), (a5) and / or ( a6) is produced, where (al), (a2) and

(a3) as well as given (a4), (a5) and (a6) in type and amount are selected so that the acrylate copolymer (Al) has the desired OH number, acid number and the desired molecular weight. Preferably, the

Acrylate copolymers (AI) have a hydroxyl number of 40 to 240, particularly preferably 60 to 210 and in particular 100 to 200, an acid number of 5 to

100, particularly preferably 10 to 60 and in particular 20 to 40,

Glass transition temperatures from -35 to + 85 ° C and number average molecular weights Mn from 1,000 to 300,000.

For the preparation of the polyacrylate resins used according to the invention, each of (a2), (a3), (a4), (a5) and (a6) copolymerizable (meth) alkyl or alkyl cycloalkyl esters having up to 20 carbon atoms in the alkyl radical can be copolymerized as (a2), in particular methyl, ethyl, propyl, n-butyl, sec-butyl, tert-butyl, hexyl, ethylhexyl, stearyl and lauryl acrylate or methacrylate; cycloaliphatic (meth) acrylic acid esters, especially cyclohexyl, isobornyl, dicyclopentadienyl, octahydro-4,7-methano-1H-indene methanol or tert-butylcyclohexyl (meth) acrylate; (Meth) acrylic acid oxaalkyl ester or oxacycloalkyl ester such as ethyl triglycol (meth) acrylate and Methoxyoligoglycol (meth) acrylate with a molecular weight Mn of preferably 550; or other ethoxylated and / or propoxylated hydroxyl-free (meth) acrylic acid derivatives; be used. These can be used in minor amounts of higher functional (meth) acrylic acid alkyl or cycloalkyl esters such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butylene glycol, pentane-1, 5-diol, hexane, 1,6-diol, octahydro -4,7-methano-1H-indene-dimethanol- or cyclohexane-1,2-, -1,3- or - 1,4-diol-di (meth) acrylate; Trimethylolpropane di- or tri (meth) acrylate; or pentaerythritol di-, tri- or tetra (meth) acrylate; included, n Within the scope of the present invention, minor amounts of higher-functional monomers are understood to mean amounts which do not lead to crosslinking or gelling of the polyacrylate resins.

Monomers (a2) which can be copolymerized with (al), (a2), (a3), (a4), (a5) and (a6) and are different from (a5) are ethylenically unsaturated monomers which carry at least one hydroxyl group per molecule and are essentially free of acid groups, such as hydroxyalkyl esters of acrylic acid, methacrylic acid or another alpha, beta-ethylenically unsaturated carboxylic acid, which are derived from an alkylene glycol which is esterified with the acid, or can be obtained by reacting the acid with an alkylene oxide, in particular hydroxyalkyl esters Acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid or itaconic acid in which the hydroxyalkyl group contains up to 20 carbon atoms, such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 3-hydroxybutyl, 4-hydroxybutyl acrylate, methacrylate, ethacrylate, crotonate, maleate, fumarate or itaconate; 1,4-bis (hydroxymethyl) cyclohexane, octahydro-4,7-methano-1H-indene-dimethanol or methyl propanediol monoacrylate, monomethacrylate, monoethacrylate, monocrotonate, monomaleinate, monofumarate or monoitaconate; or reaction products from cycüschen esters, such as epsilon-caprolactone and these hydroxyalkyl esters; or olefinically unsaturated alcohols such as AUyl alcohol or polyols such as trimethylolpropane mono- or diallyl ether or pentaerythritol mono-, di- or triallyl ether; be used. With regard to these higher-functionality monomers (a2), the same applies analogously to the higher-functionality monomers (a1). The proportion of trimethylolpropane monoallyl ether is usually 2 to 10% by weight, based on the total weight of the monomers (a1) to (a6) used to prepare the polyacrylate resin. In addition, however, it is also possible to add 2 to 10% by weight, based on the total weight of the monomers used to prepare the polyacrylate resin, of trimethylolpropane monoauryl ether to the finished polyacrylate resin. The olefinically unsaturated polyols, such as, in particular, trimethylolpropane monoauryl ether, can be used as some monomers containing hydroxyl groups, but in particular proportionally in combination with other of the monomers mentioned containing hydroxyl groups.

The monomer (a3) can be any ethylenically unsaturated monomer or a mixture of such monomers which carries at least one acid group, preferably one carboxyl group, per molecule and which is copolymerizable with (al), (a2), (a4), (a5) and (a6) be used. Acrylic acid and / or methacrylic acid are particularly preferably used as component (a3). However, other ethylenically unsaturated carboxylic acids with up to 6 carbon atoms in the molecule can also be used. Examples of such acids are ethacrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid. Furthermore, ethylenically unsaturated sulfonic or phosphonic acids or their partial esters can be used as component (a3). Other possible components (a3) are maleic acid mono (meth) acryloyloxyethyl ester, succinic acid mono (meth) acryloyloxyethyl ester and phthalic acid mono (meth) acryloyloxyethyl ester. One or more vinyl esters of monocarboxylic acids having 5 to 18 carbon atoms in the molecule and branched in the alpha position can be used as monomers (a4). The branched monocarboxylic acids can be obtained by reacting formic acid or carbon monoxide and water with olefins in the presence of a liquid, strongly acidic catalyst; the olefins can be cracked products of paraffinic hydrocarbons, such as mineral oil fractions, and can contain both branched and straight-chain acyclic and / or cycloaliphatic olefins. When such olefins are reacted with formic acid or with carbon monoxide and water, a mixture of carboxylic acids is formed in which the carboxyl groups are predominantly located on a quaternary carbon atom. Other olefinic starting materials are, for example, propylene trimer, propylene tetramer and diisobutylene. However, the vinyl esters can also be prepared from the acids in a manner known per se, for example by letting the acid react with acetylene. Because of the good availability, vinyl esters of saturated aliphatic monocarboxylic acids having 9 to 11 carbon atoms which are branched on the alpha carbon atom are particularly preferably used.

The monomer (a5) used is the reaction product of acrylic acid and / or methacrylic acid with the glycidyl ester of a monocarboxylic acid having 5 to 18 carbon atoms per molecule and branched in the alpha position. Glycidyl esters of strongly branched monocarboxylic acids are available under the trade name "Cardura". The reaction of acrylic or methacrylic acid with the glycidyl ester of a carboxylic acid with a tertiary alpha carbon atom can be carried out before, during or after the polymerization reaction. The reaction product of acrylic and / or methacrylic acid with the glycidyl ester of versatic acid is preferably used as component (a5). This glycidyl ester is commercially available under the name "Cardura El 0". Monomers (a6) which can all be copolymerized with (al), (a2), (a3), (a4) and (a5), differ from (al), (a2), (a3) and (a4) and are essentially free of acid groups ethylenically unsaturated monomers or mixtures of such monomers can be used. Coming as component (a6)

Olefins such as ethylene, propylene, but-1-ene, pent-1-ene, hex-1-ene, cyclohexene, cyclopentene, norbornene, butadiene, isoprene, cyclopentadiene and / or dicyclopentadiene;

- (Meth) acrylic acid amides such as (meth) acrylic acid amide, N-methyl -, N, N-

Dimethyl, N-ethyl, N, N-diethyl, N-propyl, N, N-dipropyl, N-butyl, N, N-dibutyl, N-cyclohexyl and / or N, N-cyclohexyl -methyl- (meth) acrylic acid amide;

- Monomers containing epoxy groups, such as the glycidyl ester of

Acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid and / or itaconic acid;

vinyl aromatic hydrocarbons, such as styrene, alpha-alkylstyrenes, in particular alpha-methylstyrene, and / or vinyltoluene;

Nitriles such as acrylonitrile and / or methacrylonitrile;

Vinyl compounds such as vinyl chloride, vinyl fluoride, vinylhylene dichloride, vinylidene difluoride; N-vinyl pyrrolidone; Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether,

Isobutyl vinyl ether and / or vinyl cyclohexyl ether; Vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate and / or the vinyl ester of 2-methyl-2-ethylheptanoic acid; and or Polysiloxane macromonomers which have a number average molecular weight Mn from 1,000 to 40,000, preferably from 2,000 to 20,000, particularly preferably 2,500 to 10,000 and in particular 3,000 to 7,000 and on average 0.5 to 2.5, preferably 0.5 to 1.5, ethylenically unsaturated Have double bonds per molecule, as described in DE-A-38 07 571 on pages 5 to 7, DE-A 37 06 095 in columns 3 to 7, EP-B-0 358 153 on pages 3 to 7 6, in US Pat. No. 4,754,014 in columns 5 to 9, in DE-A 44 21 823 or in international patent application WO 92/22615 on page 12, line 18, to page 18, line 10, or vinyl monomers containing acryloxysilane, which can be prepared by reacting hydroxy-functional silanes with epichlorohydrin and then reacting the reaction product with methacrylic acid and / or hydroxyalkyl esters of (meth) acrylic acid;

into consideration.

Vinyl aromatic hydrocarbons, in particular styrene, are preferably used.

The type and amount of components (a1) to (a6) is selected so that the polyacrylate resin (AI) has the desired OH number, acid number and glass transition temperature. Acrylate resins used with particular preference are obtained by polymerizing

(al) 20 to 60% by weight, preferably 30 to 50% by weight, of component (al),

(a2) 10 to 50% by weight, preferably 15 to 40% by weight, of component (a2),

(a3) 1 to 15% by weight, preferably 1 to 8% by weight, of component (a3), (a4) 0 to 25% by weight of component (a4),

(a5) 0 to 25% by weight of component (a5) and

(a6) 5 to 30% by weight, preferably 10 to 20% by weight, of component (a6),

the sum of the proportions by weight of components (a1) to (a6) being 100% by weight.

The acrylate copolymers (AI) used according to the invention are prepared in an organic solvent or solvent mixture which is preferably free from aromatic solvents and in the presence of at least one polymerization initiator. The polymerization initiators customary for the preparation of acrylate copolymers are used as polymerization initiators.

Examples of suitable polymerization initiators are free radical initiators, e.g. tert-butyl peroxyethyl hexanoate, benzoyl peroxide, di-tert-amyl peroxide, azobisisobutyronitrile and tert-butyl perbenzoate. The initiators are preferably used in an amount of 1 to 25% by weight, particularly preferably 2 to 10% by weight, based on the total weight of the monomers.

The polymerization is advantageously carried out at a temperature of 80 to 200 ° C., preferably 110 to 180 ° C.

Ethoxyethyl propionate and isopropoxypropanol are preferably used as solvents. The acrylate copolymer (AI) is preferably produced by a two-stage process, since the resulting coating materials according to the invention thus have better processability. Acrylate copolymers (AI) which can be obtained by

1. a mixture of the monomers (al) and (a2) and optionally (a4), (a5) and or (a6) or a mixture of parts of the monomers (al) and (a2) and, if appropriate, (a4), (a5 ) and / or (a6) is polymerized in an organic solvent and

2. after at least 60% by weight of the mixture consisting of (a1) and (a2) and optionally (a4) (a5) and / or (a6) has been added, the monomer (a3) and any remainder of the monomers (al) and (a2) and optionally (a4), (a5) and / or (a6) are added or are and further polymerized.

In addition, however, it is also possible to initially introduce the monomers (a4) and / or (a5) together with at least part of the solvent and to meter in the remaining monomers. In addition, the monomers (a4) and / or (a5) can also be added only partially together with at least part of the solvent and the rest of these monomers can be added as described above. For example, at least 20% by weight of the solvent and about 10% by weight of the monomers (a4) and (a5) and, if appropriate, parts of the monomers (al) and (a6) are preferably introduced.

Preference is also given to the preparation of the acrylate polymers (AI) used according to the invention by a two-stage process in which the first stage lasts from 1 to 8 hours, preferably from 1.5 to 4 hours, and the addition of the mixture of (a3) and the rest of the mixture, if any Monomers (al) and (a2) and optionally (a4), (a5) and (a6) within 20 to 120 Minutes, preferably within 30 to 90 minutes. After the addition of the mixture of (a3) and the rest of the monomers (a1) and (a2) and any (a4), (a5) and (a6) present, if any, is continued until the polymerization is continued until all of the monomers used are essentially complete have been implemented. The second stage can immediately follow the first. However, the second stage can only be started after a certain time, for example after 10 minutes to 10 hours.

The amount and rate of addition of the initiator is preferably chosen so that an acrylate copolymer (Al) having a number average molecular weight Mn of 1000 to 30,000 daltons is obtained. It is preferred that the initiator feed be started some time, generally about 1 to 15 minutes, before the monomers feed. Also preferred is a method in which the initiator addition begins at the same time as the monomer addition and is terminated about half an hour after the monomer addition is complete. The initiator is preferably added in a constant amount per unit of time. After the addition of the initiator has ended, the reaction mixture is kept at the polymerization temperature (as a rule 1.5 hours) until all the monomers used have been substantially completely reacted. "Substantially completely converted" is intended to mean that preferably 100% by weight of the monomers used have been reacted, but it is also possible that a low residual monomer content of at most up to about 0.5% by weight, based on the Weight of the reaction mixture can remain unreacted.

The monomers are preferred for the preparation of the acrylate copolymers

(AI) with a not too high polymerization solid, preferably with one

Polymerization solids of 80 to 50 wt .-%, based on the monomers, polymerized and then partially removed the solvent by distillation, see above that the resulting acrylate copolymer solutions (A) have a solids content of preferably 100 to 60% by weight.

For use in the coating material according to the invention, the solids content of the acrylate copolymer solutions (A) is adjusted to at least 60% by weight, preferably below 40% by weight and in particular below 30% by weight, using at least one aromatic-free solvent.

Examples of suitable solvents are ethoxyethyl propionate and butyl glycol.

The preparation of the acrylate copolymers (AI) to be used according to the invention has no special features in terms of method, but instead takes place with the aid of methods known and known in the plastics field of continuous or discontinuous copolymerization under normal pressure or overpressure in stirred tanks, autoclaves, tubular reactors or Taylor reactors.

Examples of suitable copolymerization processes are described in the patents DE-A-197 09 465, DE-C-197 09 476, DE-A-28 48 906, DE-A-195 24 182, EP-A-0 554783, WO 95/27742 or WO 82/02387.

Taylor reactors are advantageous according to the invention.

Taylor reactors which are used to convert substances under the conditions of the Taylor flow are known. They essentially consist of two coaxial, concentrically arranged cylinders, the outer of which is fixed and the inner of which rotates. The volume formed by the gap between the cylinders serves as the reaction space. With increasing angular velocity ω, - of the inner cylinder, a number of different flow forms occur, which are characterized by a dimensionless characteristic number, the so-called Taylor number Ta. The Taylor number is in addition to the angular velocity of the stirrer also depends on the kinematic viscosity v of the Huid in the gap and on the geometric parameters, the outer radius of the inner cylinder r _is, the inner radius of the outer tooth r _a and the gap width d, the difference between the two radii, according to the following formula:

Ta = ωj rj dv ^"1 (d / r _i ) ^let (I)

At low angular speeds, the laminar Couette flow, a simple shear flow, forms. If the speed of rotation of the inner cylinder is further increased, opposite rotating (counter-rotating) vortices with axes along the circumferential direction occur alternately above a critical value. These so-called Taylor vortices are rotationally symmetrical and have a diameter that is approximately as large as the gap width. Two adjacent vertebrae form a pair of vertebrae or a vertebrae line.

This behavior is based on the fact that when the inner cylinder rotates with the outer cylinder at rest, the Huid particles near the inner cylinder are subjected to a stronger centrifugal force than those which are further away from the inner cylinder. This difference in the acting centrifugal forces pushes the Huid particles from the inner to the outer tooth. The centrifugal force counteracts the viscosity force, since the friction has to be overcome when the fluid particles move. If the rotational speed increases, then the centrifugal force also increases. The Taylor vortices arise when the centrifugal force becomes greater than the stabilizing viscosity force.

In the Taylor flow with a small axial flow, each migrates

Pair of vertebrae through the gap, with only a small mass exchange between adjacent pairs of vertebrae. The mixing within such Vertebral pairs are very high, whereas the axial mixing beyond the pair boundaries is only very low. A pair of vortices can therefore be regarded as a well-mixed stirred kettle. The flow system thus behaves like an ideal flow tube in that the vortex pairs move through the gap with a constant dwell time like ideal stirred tanks.

According to the invention, Taylor reactors with an outer reactor wall and a concentrically or eccentrically arranged rotor located therein, a reactor base and a reactor cover, which together define the annular-shaped reactor volume, at least one device for metering in educts and a device for the product outlet are advantageous, the reactor wall and / or the rotor is or are geometrically designed in such a way that the conditions for the Taylor flow are met over essentially the entire reactor length in the reactor volume, ie the annular gap widens in the direction of flow.

The proportion of component (A) in the coating material according to the invention can vary very widely and depends in particular on what flexibility the sol-gel coating according to the invention produced therefrom has. The share is capped; it must not be chosen so high that there is a phase separation in the coating material according to the invention or the hardness and scratch resistance of the sol-gel coating decrease too much. The person skilled in the art can therefore, with the help of his or her specialist knowledge, possibly use the optimum proportion simple preliminary tests.

The other essential constituents of the coating material according to the invention are the base lacquer (B). It is also preferably free of aromatic solvents. It is produced by controlled hydrolysis and condensation of at least one organically modified hydrolyzable silane (B1). According to the invention, it is advantageous to use at least two silanes (B1).

The hydrolyzable silane (B1) is a compound of the general formula I

SiR, (D,

wherein the radicals R can be the same or different and are selected from hydrolyzable groups, hydroxyl groups and non-hydrolyzable groups.

The non-hydrolyzable groups R in the general formula I are preferably selected from alkyl groups, in particular with 1 to 4 carbon atoms, such as e.g. Methyl, ethyl, propyl and butyl groups; Acenyl groups, especially with 2 to 4 carbon atoms, e.g. Vinyl, 1-propenyl, 2-propenyl and butenyl groups; Alkynyl groups, in particular with 2 to 4 carbon atoms, such as acetylenyl and propargyl groups; and aryl groups, in particular with 6 to 10 carbon atoms, e.g. Phenyl and naphthyl groups. Alkyl groups are preferably used as non-hydrolyzable groups R.

Examples of hydrolyzable groups R in formula I mentioned above are hydrogen atoms; Alkoxy groups, in particular with 1 to 20 C atoms, such as methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, tert-butoxy and sec-butoxy groups; alkoxy-substituted alkoxy groups, such as, for example, beta-methoxyethoxy groups; Acyloxy groups, in particular with 1 to 4 carbon atoms, such as acetoxy and propionyloxy groups; and alkylcarbonyl groups such as acetyl groups. Particularly preferred hydrolyzable groups R are those which have no substituents and lead to aromatics-free hydrolysis products with a low molecular weight, such as, for example, lower alcohols, such as methanol, ethanol, propanol, n-butanol, i-butanol, sec-butanol and tert-butanol .

At least one group R of formula I must be a hydrolyzable group. Silanes (B1) with two, preferably four and in particular three hydrolyzable groups R are particularly preferred.

The non-hydrolyzable groups R of the silanes (B1) can contain at least one functional group. These functional groups can be, for example, epoxy groups, amino groups, olefinically unsaturated groups such as vinyl or (meth) acrylic groups, mercapto groups,

Trade isocyanate groups and / or their reaction products with other reactive compounds.

Examples of suitable hydrolyzable silanes (B1) to be used according to the invention are methyltriethoxysilane, methyltrimethoxysilane, tetramethylorthosilicate, tetraethylorthosilicate, 3-glycidyloxypropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

All or part of the silanes (B1) can be used in the form of precondensates, i.e. Compounds that are formed by partial hydrolysis of the silanes (B1), either alone or in a mixture with other hydrolyzable compounds.

The hydrolysis and condensation can optionally in the presence of organic monomers, solvents, preferably aromatics-free solvents, the organically modified described below hydrolyzable metal alkoxides (Cl) and MetaUoxiden in the form of nanoparticles.

For the hydrolysis and condensation, the silanes (B1) are precondensed with water in the desired mixing ratio. The amount of water is metered in so that local over-concentrations are avoided. This is achieved, for example, by entering the amount of water in the reaction mixture with the aid of moisture-laden adsorbents, for example silica gel or molecular sieves, water-containing organic solvents, for example 80% ethanol, or salt hydrates, for example CaCl ₂ x 6H ₂ O. Pre-condensation is preferably carried out in

However, the presence of a hydrolysis and condensation catalyst

Absence of an organic solvent.

In a further variant, the hydrolysis and condensation of the hydrolyzable silanes (B1) is carried out in the presence of an aromatic-free organic solvent, such as an aliphatic alcohol, such as methanol, ethanol, propanol, isopropanol or butanol, an ether such as dimethoxyethane, an ester such as dimethylglycol acetate or methoxypropyl acetate and / or 2-ethoxiethanol or a ketone such as acetone or methyl ethyl ketone.

Where appropriate, the metal alkoxides (Cl) and / or MetaUoxides described below can also be present as nanoparticles in the hydrolysis and condensation.

These nanoparticles are <50 nm. For example, they can be Al ₂ O ₃ , ZrO ₂ and / or TiO ₂ .

Suitable hydrolysis and condensation catalysts are proton- or hydroxyl-ion-releasing compounds and amines. Specific examples are organic or inorganic acids, such as hydrochloric acid, sulfuric acid, Phosphoric acid, formic acid or acetic acid and organic or inorganic bases such as ammonia, alkali or alkaline earth metal hydroxides, for example sodium, potassium or calcium hydroxide, and amines soluble in the reaction medium, for example lower alkylamines or alkanolamines. Volatile acids and bases, in particular hydrochloric acid, acetic acid, ammonia or triethylamine, are particularly preferred.

The precondensation is carried out so far that the resulting base lacquer (B) still has a liquid consistency.

The proportion of component (B) in the coating material according to the invention can also vary very widely and depends primarily on the scratch resistance and hardness of the sol-gel coating according to the invention produced therefrom. The share is capped; it must not be chosen so high that phase separation occurs in the coating material according to the invention and / or that the sol-gel coatings according to the invention produced therewith become too hard and brittle. The person skilled in the art can therefore determine the optimum proportion in each case on the basis of his specialist knowledge, if necessary with the aid of simple preliminary tests.

The further essential constituent of the coating material of the invention is the sol (C), which can be prepared by hydrolysis, condensation and complexation of at least one of the silanes (B1) described above and at least one hydrolyzable metal compound (Cl) of the general formula π. The sol (C) is preferably free of aromatics.

In the general formula H, the variable M stands for aluminum, titanium or zirconium, but especially aluminum. Accordingly, the index n stands for 3 or 4. In the general formula II, the variable R has the same meaning as given above for the general formula I. According to the invention, it is advantageous here if at least two, in particular three, and in the case of titanium or zirconium, three, in particular four, hydrolyzable groups are present in the aluminum case.

According to the invention, the alkoxy groups described above are particularly advantageous and are therefore used with preference. Sec-butyloxy groups are very particularly preferably used. An example of a hydrolyzable metal compound (Cl) used with very particular preference is accordingly aluminum tri-sec-butoxide.

The molar ratio of MetaU M to Siüzium can vary very widely and depends primarily on what scratch resistance should be set in the sol-gel coatings according to the invention. In general, the replacement of part of the silicon by aluminum in particular increases the scratch resistance and the hardness of the sol-gel coatings according to the invention. In particular, the molar ratio M: Si is 1:10 to 1: 1.5, preferably 1: 6 to 1: 3.

According to the invention, hydrolysis and condensation of the silanes (B1) and metal compounds (Cl) described above are carried out in the presence of at least one organic, preferably non-aromatic, compound which is capable of forming chelate ligands. These are organic compounds with at least two functional groups which can coordinate with metal atoms or ions. These functional groups are usually electron donors which donate electrons to metal atoms or ions as electron acceptors. According to the invention, organic compounds of the type mentioned are in principle suitable as long as they do not involve hydrolysis and condensation and / or adversely affect or even prevent crosslinking to the finished sol-gel coating. Examples of suitable organic compounds are compounds which contain 1,3-carbonyl groups, such as acetylacetone or ethyl acetoacetate.

The hydrolysis, condensation and complexation take place essentially under the conditions which are given above for the production of the base lacquer (B). In particular, the silanes (B1), metal compounds (Cl) and the organic compounds which are capable of forming chelates are initially introduced, after which water and at least one of the condensation catalysts described above are added to the mixture, preferably at lower temperatures, in particular 0 ° C. . The reaction can be carried out in the presence of the solvents and / or nanoparticles described above. According to the invention, however, it is advantageous to carry them out in the absence of these components. Since the resulting sol (C) is very reactive, it is advisable to store it at temperatures below 0 ° C until further use.

The proportion of constituent (C) in the coating material according to the invention can also vary very widely and depends in particular on how the property profile with regard to scratch resistance and hardness on the one hand and the flexibility on the other hand of the sol-gel coating according to the invention produced therefrom are balanced. The share is also capped here; it should not be chosen so high that phase separation occurs in the coating material according to the invention and / or that the sol-gel coatings according to the invention thus produced become too hard and brittle. The person skilled in the art can therefore determine the optimum proportion in each case on the basis of his specialist knowledge, if necessary with the aid of simple preliminary tests. Particularly advantageous coating materials according to the invention contain, based on their total amount, 5 to 40, preferably 10 to 35 and in particular 15 to 30% by weight of the acrylate copolymer solution (A), 5 to 40, preferably 10 to 35 and in particular 15 to 30% by weight .-% of the base lacquer (B) and 1 to 15, preferably 2 to 10 and in particular 3 to 8% by weight of the sol (C).

It is particularly advantageous according to the invention if the solids contents of constituents (A), (B) and (C) which are essential to the invention are selected such that they have a weight ratio of (A): (B): (C) from

0.5 to 5: 1 to 10: 1

- preferably 1 to 4: 2 to 8: 1 and

in particular 1.5 to 3: 3 to 6: 1

to stand by each other.

Furthermore, the coating material of the invention can contain an additive solution (D). It is preferably free of aromatics.

The additive solution (D) contains at least one ethylenically unsaturated compound (dl) which has at least one epoxy group. An example of a suitable compound (dl) is glycidyl (meth) acrylate.

Furthermore, it contains as component (d2) at least one silane (B1) with at least one non-hydrolyzable group R, which at least one Has epoxy group. An example of a suitable compound (d2) is 3-glycidyloxypropyltrimethoxysilane.

Last but not least, it contains at least one adduct (d3) of at least one silane (B1) with at least one non-hydrolyzable group R, which has at least one amino group, and at least one cyclic ethylenically unsaturated dicarboxylic anhydride. An example of a suitable silane (B1) is 3-aminopropyltriethoxysilane. Examples of suitable dicarboxylic anhydrides are maleic anhydride and itaconic anhydride.

Components (dl), (d2) and (d3) are contained in the additive solution in a weight ratio of (1 to 10): (1 to 30): 1, in particular (2 to 6): (10 to 20): 1 . The solids content of the additive solution (D) is preferably below 80% by weight, preferably below 60% by weight and in particular below 50% by weight.

If used, the proportion of additive solution (D) in the coating material according to the invention can vary widely. The person skilled in the art can determine the optimum proportion in each case on the basis of his specialist knowledge with the aid of simple preliminary tests.

The coating material of the invention can furthermore contain relatively large amounts of solvents, preferably aromatics-free solvents, as component (E). This is particularly the case when particularly thin sol-gel coatings according to the invention are to be produced, preferably with a dry film layer thickness <5 μm. Examples of suitable solvents (E) are the abovementioned lower alcohols, in particular ethanol, or glycol ethers such as ethyl glycol or butyl glycol. In addition, the coating material according to the invention can contain conventional and known paint additives (F). Also suitable are paint additives (F) which do not adversely affect the profile of properties of the sol-gel coatings according to the invention, in particular their optical properties (appearance) and scratch resistance, but rather vary and improve them in an advantageous manner.

Examples of suitable paint additives (F) are

UV absorber;

Radical scavenger;

Crosslinking catalysts;

- slip additives;

Polymerization inhibitors;

Defoamers;

Anticooking agents, where the targeted use of small amounts of aromatic solvents can be useful;

Emulsifiers, especially non-ionic emulsifiers such as alkoxylated alkanols and polyols, phenols and alkylphenols or anionic

Emulsifiers such as alkali salts or ammonium salts of alkane carboxylic acids, alkane sulfonic acids, and sulfonic acids of alkoxylated alkanols and polyols, phenols and alkylphenols; Wetting agents such as siloxanes, fluorine-containing compounds,

Carboxylic acid esters, phosphoric acid esters, polyacrylic acids and their copolymers or polyurethanes;

Adhesion promoter;

Leveling agent;

educational aids such as CeUulose derivatives;

Flame retardants or

rheology-controlling additives such as those known from the patent specifications WO 94/22968, EP-A-0 276 501, EP-A-0 249 201 or WO 97/12945; crosslinked polymeric microparticles, such as are disclosed, for example, in EP-A-0 008 127; inorganic layered silicates such as aluminum-magnesium-silicate, sodium-magnesium and

Sodium magnesium fluorine lithium layered silicates of the

Montmorillonite type; Silicas such as aerosils; or synthetic polymers with ionic and / or associative groups such as

Polyvinyl alcohol, poly (meth) acrylamide, poly (meth) acrylic acid,

Polyvinylpyrrohdon, styrene-maleic anhydride or

Ethylene-maleic anhydride copolymers and their derivatives or hydrophobically modified ethoxylated urethanes or polyacrylates.

Further examples of suitable additives (F) are described in the textbook "Lackadditive" by Johan Bieleman, Wiley-VCH, Weinheim, New York, 1998. The coating material of the invention has a solids content of up to 80, preferably up to 60, particularly preferably up to 40 and in particular up to 20% by weight. If particularly thin sol-gel coatings according to the invention, ie coatings with a thickness of <5 μm, are to be produced, it is advisable to choose a solids content of less than 20% by weight.

The coating material of the invention is not peculiar, but is carried out in a customary and known manner by mixing its essential constituents (A), (B) and (C) and, if appropriate, (D), (E) and / or (F) in usual and known mixing units such as dissolvers. The components can be mixed with one another in any way. For example, they can be poured into the mixing unit at once and mixed together. According to the invention, however, it is advantageous to initially introduce the sol (C) in order then to add the remaining constituents one after the other. It has proven useful here to add the base lacquer (B) before the acrylate copolymer solution (A). If a solvent (E) is used, it is advantageously added after the addition of the base lacquer (B) and before the addition of the constituent (A) and, if appropriate, (D). If coating additives (F) are used, they are advantageously added after the addition of the base coating (B) and before the addition of the constituent (A). If solvents (E) and paint additives (F) are used, the paint additives (F) are added before adding the solvents (E).

The coating materials according to the invention are outstandingly suitable for the production of the sol-gel coatings according to the invention, in particular sol-gel clearcoats.

According to the invention, every conceivable substrate can be coated with them.

Examples include substrates made of metal, plastic, glass, wood or ceramic. These substrates can be provided with a primer. In the event of plastic can be a so-called hydro-primer; in the case of MetaU, the substrate can also have been subjected to a surface treatment, for example galvanizing or phosphating or anodizing. Furthermore, an electro-dip coating and a filler can be present as a primer on the metal substrate.

The application of the coating materials according to the invention has no special features in terms of method, but rather the customary application methods, such as spraying, knife coating, brushing, pouring, dipping or rolling, can be used.

After their application, the coating materials according to the invention are hardened, which results in the sol-gel coatings according to the invention. If necessary, pre-drying can also be carried out before curing. The usual and known methods and devices such as forced air ovens can also be used for this. According to the invention, however, it is advantageous to harden the coating materials according to the invention with medium IR radiation. This makes it possible to coat only parts of substrates or single-layer or multi-layer paints in a targeted manner at damaged or particularly exposed locations and to provide them with a scratch-resistant finish without the other parts being affected by thermal stress. This makes it possible to use the coating materials according to the invention in automotive refinishing. Since the amount of coating material according to the invention can also be kept to a minimum, its use is also particularly economical.

The coating materials of the invention can be applied directly to the substrates in order to then form a scratch-resistant sol-gel coating according to the invention after curing. In this way, substrates, as are usually used for the manufacture of vehicles, can be produced from other components and devices, such as radiators or containers, or of furniture are made scratch-resistant.

The particular advantages of the coating materials according to the invention are, however, particularly evident when they are used for coating single-layer or multi-layer coatings with the sol-gel coatings according to the invention. It proves to be particularly advantageous here that the single-layer or multi-layer coatings can be fully cured.

Accordingly, the coating materials according to the invention are suitable for the coating of single-layer or multi-layer coatings, as are customary and known in the fields of automotive painting, car refinishing, industrial painting, including container coatings, plastic painting and furniture painting.

Examples of single-layer paints of this type are the solid-color topcoats known from automotive OEM coating, which contain binders, crosslinking agents and effect and / or color pigments.

Examples of multi-layer paints are the paints which contain an effect and / or color-imparting basecoat, in particular a water-based basecoat, and a clearcoat, and in the context of initial automotive painting by the wet-on-wet process, as described, for example, in the patents US-A -3,639,147, DE-A-3 33 332, DE-A-38 14 853, GB-A-2 012 191, US-A-3,953,644, EP-A-0 260447, DE-A-39 03 804, EP -A-0 320 552, DE-A-36 28 124, US-A-4,719,132, EP-A-0 297 576, EP-A-0 069 936, EP-A-0 089 497, EP-A-0 195 931, EP-A-0 228 003, EP-A-0 038 127 and DE-A-28 18 100, or can be produced in the course of car refinishing. The coating materials of the invention are in particular Particularly well suited for coating multi-layer coatings of this type.

Examples of suitable waterborne basecoats and the corresponding multilayer coatings are from the patents EP-A-0089497, EP-A-0256 540, EP-A-0 260447, EP-A-0 297 576, WO 96/12747, EP-A-0 523 610, EP-A-0 228 003, EP-A-0 397 806, EP-A-0 574 417, EP-A-0 531 510, EP-A-0 581 211, EP-A-0 708 788 , EP-A-0 593 454, DE-A-43 28 092, EP-A-0 299 148, EP-A-0 394 737, EP-A-0 590 484, EP-A-0 234 362, EP -A-0 234 361, EP-A-0 543 817, WO 95/14721, EP-A-0 521 928, EP-A-0 522 420, EP-A-0 522 419, EP-A-0 649 865, EP-A-0 536 712, EP-A-0 596 460, EP-A-0 596 461, EP-A-0 584 818, EP-A-0 669 356, EP-A-0 634 431, EP-A-0 678 536, EP-A-0 354 261, EP-A-0 424 705, WO 97/49745, WO 97/49747 or EP-A-0401 565 are known.

Examples of suitable one-component (IC), two-component (2K) or multicomponent (3K, 4K) clearcoats are, for example, from the patents DE-A-42 04 518, US-A-5,474,811, US-A-5,356,669, US-A -5,605,965, WO 94/10211, WO 94/10212, WO 94/10213, EP-A-0 594 068, EP-A-0 594 071, EP-A-0 594 142, EP-A-0 604 992, WO 94/22969, EP-A-0 596 460 or WO 92/22615 are known.

Em component (IC) clearcoats are known to contain hydroxyl-containing binders and crosslinking agents such as blocked polyisocyanates, tris (alkoxycarbonylamino) triazines and / or aminoplast resins. In a further variant, they contain, as binders, polymers with pendant carbamate and / or AUophanatgruppen and possibly carbamate and / or AUophanat modified aminoplast resins as crosslinking agents. It is known that two-component (2K) or multicomponent (3K, 4K) clearcoats contain, as essential components, binders containing hydroxyl groups and polyisocyanates as crosslinking agents, which are stored separately until they are used.

Examples of suitable powder clearcoats are known, for example, from German patent specification DE-A-42 22 194 or the product information from BASF Lacke + Farben AG, "Powder coatings", 1990.

Powder clear lacquers are known to contain epoxy group-containing binders and polycarboxylic acids as crosslinking agents.

Examples of suitable powder slurry clearcoats are known, for example, from US Pat. No. 4,268,542 and German patent applications DE-A-195 18 392.4 and DE-A-196 13 547 or are described in the unpublished German patent application DE-A-198 14471.7.

Powder slurry clearcoats are known to contain powder clearcoats dispersed in an aqueous medium.

As is known, they contain low molecular weight, oligomeric and / or polymeric compounds curable with actinic light and / or electron radiation, preferably radiation-curable binders, in particular based on ethylenically unsaturated prepolymers and / or ethylenically unsaturated oligomers, optionally one or more reactive diluents and optionally one or more photoinitiators. Examples of suitable radiation-curable binders are (meth) acrylic functions (Meth) acrylic copolymers, polyether acrylates, polyester acrylates, unsaturated polyesters, epoxy acrylates, urethane acrylates, amino acrylates, melamine acrylates, silicone acrylates and the corresponding methacrylates. It is preferred to use binders which are free from aromatic structural units.

However, multilayer clear coat layers can also be used, such as a clear coat layer based on binders containing hydroxyl groups and blocked polyisocyanates and aminoplasts as crosslinking agents, which immediately adheres to the water-based lacquer layer and over which there is another clear coat layer based on binders containing carbamate and / or allophanate groups and aminoplasts as crosslinking agents.

In the procedure according to the invention, the single-layer or multilayer coatings, in particular the clear lacquers, are cured before the coating material of the invention is applied. This represents a further particular advantage of the coating material and the method according to the invention, because the painting methods and devices usually used in operation do not have to be modified; after carrying out a customary and known method, essentially only one further painting step has to be carried out, essentially independently of this.

It proves to be a further particular advantage that the clear coating layers usually used can be coated with the coating material of the invention.

The sol-gel coatings according to the invention, which consist of the inventive

Coating materials, preferably produced by the process according to the invention, are notable for excellent scratch resistance with very good adhesion, even after exposure to condensation water. Also the Appearance is very good. The method according to the invention is therefore particularly suitable for painting vehicle bodies, in particular automobile bodies, with multi-layer coatings, industrial painting, including container coatings, plastic painting and furniture painting.

Examples

Manufacturing example

The preparation of the sol-gel clearcoat according to the invention

1. The production of a base coat

30 parts of demineralized water, 40 parts of ethyl glycol, 5 parts of acetic acid (100%), 66.5

Parts of methyltriethoxysilane and 4.7 parts of 3-glycidyloxypropyltrimethoxysilane are introduced and heated to 60 ° C. with stirring. After a further 3 hours at 60 ° C., the reaction mixture was heated to 90 ° C. with stirring and during 2

Heated at this temperature for hours. Then 70 parts of the reaction mixture were azeotroped at 85 ° C. After cooling down

5 parts of methoxypropyl acetate and 0.1 part of BYK® 301 (leveling agent from BYK) were added to the reaction temperature at room temperature. This resulted in master varnish 1 with a theoretical solids content of 37

Wt .-% and an experimentally determined solids content of 45 wt .-% (1 hour / 130 ° C).

2. The manufacture of an acrylate copolymer for modifying the sol-gel clearcoat 39 parts of ethoxyethyl propionate were placed in a suitable stirred kettle with reflux condenser and stirring and heated to 130.degree. In a first monomer feed vessel, 9.598 parts of butyl methacrylate, 7.708 parts of methyl methacrylate, 8.003 parts of styrene, 4.253 parts of methacrylic ester 13.0 (methacrylic acid ester with a long alkyl radical in the ester part) and 9.096 parts of hydroxyethyl acrylate were premixed. 3.810 parts of hydroxyethyl acrylate, 1.831 parts of acrylic acid and 0.916 parts of ethoxyethyl propionate were placed in a second monomer feed vessel. 3,692 parts of peroxide TBPEH (tert-butyl perethylhexanoate) and 6.025 parts of ethoxyethyl propionate were placed in an initiator feed vessel. The contents of the first monomer feed vessel were metered uniformly into the reactor over four hours. The second monomer feed was started two hours and 30 minutes after the start of the first monomer feed. For this purpose, the contents of the second monomer feed vessel were metered uniformly into the reactor over an hour and 30 minutes. The contents of the initiator feed vessel were metered uniformly into the reactor over four hours and 30 minutes, starting with the initiator feed five minutes before the first monomer feed. After the feed, the resulting reaction mixture was polymerized at 130 ° C. for two hours until an original viscosity of 2.2 dPas, a solids content of 50% by weight (15 minutes / 180 ° C.) and an acid number of 30 mg KOH / g was reached were. The ethoxyethyl propionate was then distilled off in vacuo at 100 ° C. until a solids content of 81% by weight was reached. The resulting reaction mixture was cooled to 80 ° C. and adjusted to a solids content of 75% by weight with butyl glycol and ethoxyethyl propionate (weight ratio 5: 1).

For the preparation of the sol-gel clearcoat material according to the invention, the solution of the acrylate copolymer with butylglycol was admitted to a solids content of 20% by weight, and the solution for organic modification 2 resulted. 3. The preparation of a sol to be used according to the invention

A mixture of 138.6 parts of aluminum tri-sec-butoxide, 178.3 parts of methyltriethoxysilane, 401.78 parts of 3-glycidyloxypropyltrimethoxysilane and 82.6 parts of ethyl acetoacetate was placed in a suitable reaction vessel at 0.degree. 198.72 parts of 0.1 N hydrochloric acid were metered in at 0 ° C. for presentation. After the addition, the resulting reaction mixture was aged at room temperature for 24 hours. At 100% conversion, the theoretical solids content was 37.88% by weight and the theoretical solvent content was 53J 1% by weight. The experimentally determined solids content was 44.6% by weight (15 minutes / 180 ° C). The pH of the ormocere solution was 3J. The viscosity (original) was 20 mPas at a shear rate D = 103 s ^"1. The sol was stored at -18 ° C. until it was used to produce the sol-gel clearcoat material according to the invention.

The preparation of the sol-gel clearcoat according to the invention

Sol-gel clearcoat 4 was obtained by introducing 9.81 parts of sol 3 and successively 35.8 parts of base coat 1 (45% by weight in ethyl glycol), 0.2 part of BYK® 301, 65 Parts of ethanol and 40 parts of the solution for organic modification 2 were added with stirring and the constituents were mixed together. The sol-gel clearcoat 4 according to the invention with a solids content of 19% by weight resulted.

example

1. The production of a sol-gel coating according to the invention on a multilayer coating A commercially available filler from BASF Coatings AG was first applied and baked onto a steel pistol coated with a commercially available electrocoat (cathodic coating with a layer thickness of 18-22 μm). The result was a filler layer with a layer thickness of 35 to 40 μm. A commercial black uni base coat from BASF Coatings AG was then applied to the filler in the same way and predried at 80 ° C. for 10 minutes. After the panels had been cooled, a layer of a commercially available two-component (2K) clearcoat (FF98-0015 from BASF Coatings AG) was applied and predried at 50 ° C. for 10 minutes and then together with the basecoat at 140 ° C. for 45 minutes networked. The result was a basecoat layer with a thickness of 15 μm and a clear lacquer layer with a thickness of 44 μm. The black uni base coat was chosen because the best way to observe the formation of scratches on the corresponding test panels.

After cooling, the sol-gel clearcoat 4 according to the invention was applied in accordance with the preparation example, so that after curing with medium IR radiation (distance of the radiator from the surface 18 cm; radiator: module infrared radiator MMS 2000 from Haraeus) the sol according to the invention -Gel coating of a thickness of 4.5 μm resulted.

2. Testing the properties of the sol-gel coating according to the invention

2.1 Liability of the sol-gel coating

TabeUe 1 gives an overview of the mechanical-technological tests and the results obtained. Table 1:

Adhesion strength of the sol-gel coating according to the invention

Test methods example

Scratch test according to DBL 7399 [grade 0 to 5] 0

Scratch test after 240 hours of condensed water (SKK) [grade 0 to 5] 0

Cross cut according to DIN 53151 (2 mm) [grade 0 to 5] 0

Cross-cut after 240 hours of SKK and 24 hours of regeneration 0

[Grade 0 to 5]: 0 = best value; 5 = worst value

Although the clear lacquer had been completely burned in before it was overlaid with the sol-gel coating, the sol-gel coating was not detached.

2.2 The scratch resistance of the sol-gel coating after the brush test For this test, the test panels were stored at room temperature for at least 2 weeks after the coatings had been applied before the test was carried out.

The scratch resistance of the sol-gel coating on the test panels was determined using the BASF described in FIG. 2 on page 28 of the article by P. Betz and A. Bartelt, Progress in Organic Coatings, 22 (1993), pages 27-37 -Brush tests, which were modified with regard to the weight used (2000 g instead of the 280 g mentioned there), were assessed as follows:

In the test, the paint surface was damaged with a sieve fabric that was loaded with a mass. The screen cloth and the lacquer surface were wetted with a detergent solution. The test panel was moved back and forth under the screen fabric in a lifting motion by means of a motor drive.

The test specimen was eraser covered with nylon sieve mesh (No. 11, 31 μm mesh size, Tg 50 ° C.) (4.5 × 2.0 cm, wide side perpendicular to the direction of scratching). The coating weight was 2000 g.

Before each test, the screen mesh was renewed, the direction of the mesh of the mesh was paraUel to the direction of scratching. With a pipette, approx. 1 ml of a freshly stirred 0.25% Persil solution was applied in front of the eraser. The number of revolutions of the motor was set so that 80 double strokes were carried out in a time of 80 s. After the test, the remaining washing liquid was rinsed off with cold tap water and the test panel was blown dry with compressed air.

It was found here that the sol-gel coatings according to the invention were not scratched at all. 2.3 The lubricity (slip) of the sol-gel coating according to the invention

The surface slip was made using the slip measuring device MOD 9505AE - SERIAL 7035-0689-2 from ALTEK, P.O. Box 1128, Torrington, Connecticut 06790, USA. In this case, a weight provided with three hemispheres was pulled over the surface of the test panels with a constant force. The resulting frictional resistance was graphically represented with the help of an x / y plotter as a dimensionless quantity. The height of the resulting peak is a relative measure of the slidability of the surface in question: the lower the height, the more slidable the surface.

In this test, the sol-gel coating had a relative peak height of 0.06. For comparison, the commercially available two-component (2K) clearcoat (FF98-0015 from BASF Coatings AG) used for the production of the multilayer coating had a relative peak height of 0.05.

2.4 Chemical resistance

2.4.1 Chemical resistance according to the MB gradient oven test

In the MB gradient oven test, which is well known to the person skilled in the art, the test panels of the example were exposed to damage by sulfuric acid, water, pancreatin and tree resin. For this purpose, the test substances were applied at intervals of one segment width (setting the gradient to 30-75 ° C [1 ° C per heating segment]). After storage for 72 hours in a standard climate of 23 ° C., the test panels were loaded on a gradient oven (eg type: 2615 from BYK-Gardner) for 30 minutes. The temperature at which the first visible change occurred was determined. The test results can be found in TabeUe 2.

Table 2: Chemical resistance according to the MB gradient oven test

Test substance example

1. Mark at ° C

1% sulfuric acid 54

Distilled water > 75

Pancreatin 48

Tree resin> 75

The results of the MB gradient oven test confirm the high chemical resistance of the sol-gel coating according to the invention.

2.4.2 Resistance to dishwasher detergents

A dishwasher cleaner with a pH of 10.8 was used for this test. The test panels were loaded with the amounts of cleaner shown in Table 3 in the stated concentrations for 30 minutes at 23 ° C (Kharma room) or 30 ° C (forced air oven). The resulting damage was rated as follows:

Note meaning

0 no damage 1 slight discoloration

2 discoloration

3 edge marking

Table 3 gives an overview of the results obtained.

Table 3: Resistance of the sol-gel coating according to the invention to dishwasher detergents

Amount of detergent temperature concentration ⁽ ml ⁾ ___ l__ ___.

0.025 23 0 0

0.8025 30 1 1

0.05 30 0 0

0.075 30 0 0

0J 30 0 0

0.125 30 0 0

The values in Table 3 underpin the high chemical stability of the sol-gel coating according to the invention.

2.5 Stone chip test The rock impact test under multi-impact loads (2x500 grams / 2 bar) from AUDI AG known to the experts provided a characteristic value of 3 and a degree of rust of 2. Accordingly, the sol-gel coating according to the invention, together with the multilayer coating, proved to be sufficiently stable Falling rocks.

2.6 Erichsen deepening

The Erichsen depth according to DIN EN ISO 1520: 1995-04 was 0.9 mm.

2.7 Appearance

2.7.1 ripple

The waviness of the sol-gel coating according to the invention was measured using the Wavescan method. For this purpose, a laser beam was directed onto the surface at an angle of 60 °, and the fluctuations in the reflected light were recorded on a measuring stick of 10 cm using a measuring device.

In the so-called long wave range (0.6 to 10 mm; observation distance: 2.5 m), a value of 8.0 was determined. So there were no orange peel structures or other defects in the paint.

In the so-called short wave range (0J to 0.6 mm; observation distance: 45 cm), a value of 27.9 was determined. Thus, there were few, if any, fine structures on the surface of this size.

2.7.2 Shine and Haze Gloss and haze were measured reflectometrically at an angle of 20 ° using a BYK reflectometer. The sol-gel coating according to the invention had a gloss of 75 and a haze of 23 and thus also met the requirements of practice in this regard.

Claims

claims

1. Sol-gel coating material containing

(A) an acrylate copolymer solution containing at least one

a3) at least one at least one acid group, which can be converted into the corresponding acid anion group, per molecule-carrying ethylenically unsaturated monomer;

(B) a base lacquer which can be prepared by hydrolysis and condensation of at least one hydrolyzable silane (B1) of the general formula I

SiR, (I),

where the variable R has the following meaning:

R = hydrolyzable groups, hydroxyl groups and non-hydrolyzable groups, with the proviso that at least one, preferably at least there are two hydrolyzable group (s);

and

MR _n (II),

where the variables and the index have the following meaning:

M = aluminum, titanium or zirconium,

n = 3 or 4.

2. The sol-gel coating material according to claim 1, characterized in that it is free of aromatics.

3. The sol-gel coating material according to claim 1 or 2, characterized in that it, based in each case on its total amount, 5 to 40, preferably 10 to 35 and in particular 15 to 30 wt .-% of Acrylate copolymer solution (A) contains 5 to 40, preferably 10 to 35 and in particular 15 to 30% by weight of the base lacquer (B) and 1 to 15, preferably 2 to 10 and in particular 3 to 8% by weight of the sol (C) .

4. The sol-gel coating material according to one of claims 1 to 3, characterized in that the solids contents of the components (A), (B) and (C) in a weight ratio of (A): (B): (C) of

- 0.5 to 5: 1 to 10: 1

preferably 1 to 4: 2 to 8: 1 and

especially 1,

5 to 3: 3 to 6: 1

to stand by each other.

The sol-gel coating material according to one of claims 1 to 4, characterized in that

the non-hydrolyzable groups R alkyl groups, in particular with 1 to 4 carbon atoms; Acenyl groups, in particular with 2 to 4 carbon atoms; Alkynyl groups, in particular with 2 to 4 carbon atoms; and or aryl groups, in particular with 6 to 10 carbon atoms; and

the hydrolyzable groups R are hydrogen atoms, alkoxy groups, in particular with 1 to 20 C atoms; alkoxy-substituted alkoxy groups with 3 to 20 C atoms; Acyloxy groups, in particular with 1 to 4 carbon atoms; Alkylcarbonyl groups, in particular with 2 to 6 carbon atoms; are.

6. The sol-gel coating material according to claim 5, characterized in that

the hydrolyzable groups R methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, sec-butoxy, beta-methoxy-ethoxy, acetoxy, propionyloxy and / or acetyl groups and the

the non-hydrolyzable groups R are methyl, ethyl, propyl, butyl-vinyl, 1-propenyl, 2-propenyl, butenyl, acetylenyl, propargyl, phenyl and / or and naphthyl groups.

7. The sol-gel coating material according to any one of claims 1 to 6, characterized in that the non-hydrolyzable groups R at least one functional group, in particular at least one epoxy group, amino group, olefinically unsaturated group, mercapto group, and / or isocyanate group and or their Reaction products with other reactive compounds.

8. The sol-gel coating material according to one of claims 1 to 7, characterized in that organic compounds are used for complexation, which form chelate ligands.

9. The sol-gel coating material according to one of claims 1 to 8, characterized in that it is a sol-gel clearcoat.

10. The use of the sol-gel coating material according to one of claims 1 to 9 for the production of scratch-resistant sol-gel coatings, in particular for single-layer or multi-layer coatings.

11. The use of the sol-gel coating material according to claim 10, characterized in that it is cured single-layer or multi-layer coatings.

12. The use of the sol-gel coating material according to claim 10 or 11, characterized in that it is in the coatings

Vehicle painting, vehicle refinishing, industry

Paintwork, including container coatings, plastic painting and

Furniture paints deals.

13. Process for the production of scratch-resistant sol-gel coatings on single-layer or multi-layer coatings

(iii) curing the sol-gel coating material,

characterized in that a sol-gel coating material according to one of claims 1 to 9 is used.

14. The method according to claim 13, characterized in that the applied sol-gel coating material is cured by irradiation with medium IR radiation.

15. The method according to claim 13 or 14, characterized in that the single-layer or multi-layer coating is fully cured.

16. The method according to any one of claims 13 to 15, characterized in that it is in the coatings

Original automotive paintwork, automotive refinishing, industrial

Paintwork, including container coatings, plastic painting and

MöbeUackierungen is concerned.

17. Sol-gel coatings, producible from a sol-gel coating material according to one of claims 1 to 9 and / or by the method according to one of claims 13 to 16.

18. Substrates containing at least one sol-gel coating according to claim 18.