EP1165700A1

EP1165700A1 - Sol-gel coating for single-layer or multi-layer varnishes

Info

Publication number: EP1165700A1
Application number: EP00914111A
Authority: EP
Inventors: Peter Betz; Wilfried STÜBBE; Horst HINTZE-BRÜNING; Heinz-Peter Rink
Original assignee: BASF Coatings GmbH
Current assignee: BASF Coatings GmbH
Priority date: 1999-03-06
Filing date: 2000-03-06
Publication date: 2002-01-02
Also published as: AU3554100A; WO2000053683A1; US6872765B1; DE19909894A1; JP2002538281A

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, provided that there should be at least one, preferably two, hydrolysable groups; and (C) an additive solution containing c1) at least one ethylenically unsaturated compound containing at least one epoxide group; c2) at least one silane (B1) with at least one non-hydrolysable group R presenting at least one epoxide group; and c3) at least one adduct of at least one silane (B1) with at least one non-hydrolysable group R presenting at least one amino group and at least one cyclic ethylenically unsaturated dicarboxylic acid anhydride. The invention also relates to the use of said sol-gel coating material for producing scratchproof sol-gel coatings.

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 method for producing 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 effect and / or color-giving paint system. Clear varnishes are often applied as the last coating layer. The usual and known two-component (2K) or multicomponent (3K, 4K) clearcoats are suitable for this.

As is known, two-component (2K) or multicomponent (3K, 4K) clearcoats contain, as essential constituents, binders, with functional groups which can react with isocyanate groups, and polyisocyanates with free isocyanate groups as crosslinking agents. The two essential components are stored separately until they are used. Both aqueous and conventional two-component (2K) or multi-component (3K, 4K) clearcoats are known. An example of an aqueous system can be found in German patent DE-A-44 21 823. These clear coats provide weather-resistant coatings, which, however, are often not sufficiently scratch-resistant under heavy use. Scratches are, however, already visually disturbing if the clear lacquer surface is only deformed without material being removed in the process.

The automobile bodies, in particular for commercial vehicles, can, however, also have single-layer effect and / or coloring coatings, which also are referred to as solid-color top coats. Both one-component (1K) and two-component (2K) undercoat lacquers are used. As is known, the one-component (IC) undercoat materials contain self- or externally crosslinking binders and, for example, aminoplast resins or blocked polyisocyanates as crosslinking agents. The two-component (2K) uni topcoats contain binders with functional groups that can react with isocyanate groups and polyisocyanates with free isocyanate groups as crosslinking agents. Paints of this type are also used as car refinish paints. As with the two-component (2K) clearcoats, their two essential components are stored separately from each other until they are used. Solid-color top coats have a scratch resistance, which sometimes does not meet the particularly heavy loads to which commercial vehicles are often exposed.

So-called sol-gel clearcoats based on siloxane-containing paint formulation oranges have recently been developed, 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, 40 25 215, 38 28 098, 40 20 316 or 41 22743 .

Sol-gel clear coats give plastic substrates such as B. glasses or motorcycle helmet visors have a very good scratch resistance. This scratch resistance is not achieved by the well-known OEM (Original Equipment Manufacturing) clearcoats, which are usually used for the initial painting of vehicles. The automotive industry is now required to transfer this improved scratch resistance to the clearcoat layers and solid-color lacquer layers used in the painting of automobiles.

However, the replacement of the OEM clear coats usually used in automotive painting by sol-gel clear coats is not easily possible because they for this z. 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 clearcoat or solid-color topcoats results in adhesion problems between these painting poles and the sol-gel coating, which occur in particular after stone chipping and when exposed to condensation.

The object of the present invention is to provide a new sol-gel coating material which allows the advantageous properties of the sol-gel coatings with the advantageous properties of the known single-layer or multi-layer coatings, in particular the single- or multi-layer effect and / or to combine color-imparting painting orifices for automotive OEM painting without causing problems of liability.

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 essentially acid-free (meth) acrylic acid ester,

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 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, (D,

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) containing an additive solution

cl) at least one ethylenically unsaturated compound containing at least one epoxy group,

c2) at least one silane (B1) with at least one non-hydrolyzable group R, which has at least one epoxy group, and

c3) at least one adduct 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.

In the following, the new sol-gel coating material is referred to as “coating material according to the invention”.

In addition, the new process for the production of sol-gel coatings by applying and curing sol-gel coating materials on ungranded or primed substrates or ungranded or primed substrates, which are provided with a single-layer or multi-layer coating, was found, in which the Coating material according to the invention used and / or in which prior to the application of a sol-gel coating material

(il) a one-coat paint system based on a one-component (LC) clear coat, two-component (2K) or multi-component (3K, 4K) clear coat, powder clear coat or UV-curable clear coat,

(i2) a multi-layer effect and / or color coating with a top layer based on a one-component (IC) clear coat,

Two-component (2K) or multi-component (3K, 4K) clear coat, powder clear coat or UV-curable clear coat or

(i3) a single-layer effect and / or color-imparting paint based on a solid-color paint

applied and partially cured. In the following, the new processes for the production of sol-gel coatings are referred to collectively as "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 underlying the invention 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 painting rods without problems, without it falling in the event of stone chipping or after exposure to condensation, i.e. H. a ten-day exposure of the layers in an atmosphere of 40 ° C and 100% relative humidity, comes off or cracks. The optical properties of the painting rods provided with the sol-gel coatings according to the invention also meet all requirements.

The coating material according to 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 Inorganic 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. Tetramethylorthosilicate (TMOS) or tetraethylorthosilicate (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 metal alcoholates. It gains 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 grand framework, if organic radicals, preferably those with olefinically unsaturated groups and / or epoxy groups, can be used.

The modification takes place according to the invention in that a finished organic polymer is present during the hydrolysis and condensation of the starting products or in the sol.

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

Component (A) is an acrylate copolymer solution which 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 lies 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 is obtained by copolymerizing the monomers (al), (a2) and (a3) mentioned below and, if appropriate, further monomers (a4), (a5) and or (a6 ) is prepared, wherein (al), (a2) and (a3) and optionally (a4), (a5) and (a6) are selected in type and amount such that the acrylate copolymer (Al) has the desired OH number, acid number and has the desired molecular weight. The acrylate copolymers (Al) preferably 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 1,500 to 300,000.

For the preparation of the polyacrylate resins used according to the invention, as monomer (a1) any (meth) acrylic acid alkyl or cycloalkyl ester having up to 20 carbon atoms in the alkyl radical copolymerizable with (a2), (a3), (a4), (a5) and (a6), 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-IJ-, 1,3- or - 1,4-diol-di (meth) acrylate; Trimethylolpropane di- or tri (meth) acrylate; or pentaerythritol di-, tri- or tetra (meth) acrylate; contain. In the context of the present invention, minor amounts of higher-functional monomers are understood to mean those 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 acids 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 of acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid or itaconic acid, in which the hydroxyalkyl group up to Contains 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-1 H-indene-dimethanol or methyl propanediol monoacrylate, monomethacrylate, monoethacrylate, monocrotonate, monomaleinate, monofumarate or monoitaconate; or reaction products from cyclic esters, such as, for example, epsilon-caprolactone and these hydroxyalkyl esters; or olefinically unsaturated alcohols such as allyl alcohol or polyols such as trimethylolpropane mono- or diallyl ether or pentaerythritol mono-, di- or triallyl ether; be used. With regard to these higher functional monomers (a2), the same applies analogously to the higher functional 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 monoallyl ether to the finished polyacrylate resin. The olefinically unsaturated polyols, such as, in particular, trimethylolpropane monoallyl ether, can be used as the sole monomers containing hydroxyl groups, but particularly in proportion in combination with other monomers mentioned containing hydroxyl groups.

As monomer (a3) each can be at least one acid group, preferably one

Carboxyl group, per molecule, with (al), (a2), (a4), (a5) and (a6) copolymerizable, ethylenically unsaturated monomer or a mixture of such monomers can 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 E10".

As monomers (a6), all of which can 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, vinylidene 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 im

Means 0.5 to 2.5, preferably 0.5 to 1.5, ethylenically unsaturated double bonds per molecule, as described in DE-A-38 07 571 on pages 5 to 7 of DE-A 37 06 095 in columns 3 to 7, EP-B-0 358 153 on pages 3 to 6, in US A 4,754,014 in columns 5 to 9, in DE-A 44 21 823 or in that of international

Patent application WO 92/22615 on page 12, line 18 to page 18, line 10, or acryloxysilane-containing vinyl monomers, 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 which are customary for the preparation of acrylate copolymers are used as polymerization initiators.

Examples of suitable polymerization initiators are free radical initiators, such as, for example, tert-butyl peroxyethyl hexanoate, benzoyl peroxide, di-tert. Amyl peroxide, azobisisobutyronitrile and tert-butyl perbenzoate called. 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 optionally (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) is or are added 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) are only partially added to the initial charge together with at least part of the solvent and the rest of these monomers are 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 in accordance with 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) are carried out within 20 to 120 minutes, preferably within 30 to 90 minutes. After the addition of the mixture of (a3) and the optionally present remainder of the monomers (al) and (a2) and optionally (a4), (a5) and (a6) has ended, 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 continued for as long (as a rule 1.5 Hours) kept at the polymerization temperature until essentially all of the monomers used had been 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 for the preparation of the acrylate copolymers (AI) are preferably polymerized in the case of a polymerization solid which is not too high, preferably at a polymerization solids content of 80 to 50% by weight, based on the monomers, and the solvents are then partially removed by distillation, so that the acrylate copolymer solutions formed (A) have a solids content of preferably 100 to 60% by weight.

For use in the coating material of the invention, the solids content of the acrylate copolymer solutions (A) is adjusted to at least 60% by weight, more preferably less than 40% by weight and in particular less than 30% by weight with at least one preferably 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 takes place with the aid of the methods of continuous or discontinuous copolymerization which are customary and known in the plastics field, 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 CÖ; of the inner cylinder occur a number of different flow forms, which are characterized by a dimensionless characteristic number, the so-called Taylor number Ta. In addition to the angular velocity of the stirrer, the Taylor number is also dependent on the kinematic viscosity v of the fluid in the gap and on the geometric parameters, the outer radius of the inner cylinder, the inner radius of the outer cylinder r _a and the gap width d, the difference between the two radii , according to the following formula:

Ta = (Oi Ti dv ^"1 (d / r _i ) ^{1 2} (D

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 vertebral cell. This behavior is based on the fact that when the inner cylinder rotates with the outer cylinder at rest, the fluid 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 fluid particles from the inner to the outer cylinder. 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 pair of vortices travels through the gap, with only a small mass exchange occurring between adjacent pairs of vortices. The mixing within such vortex pairs is 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 bottom and a reactor cover, which together define the annular-shaped reactor volume, at least one device for metering in starting materials and a device for the product outlet are advantageous, the reactor wall and / or the rotor is or are geometrically designed such that the conditions for the Taylor flow are met over substantially the entire length of the reactor in the reactor volume, ie the annular gap widens in the direction of flow. The proportion of constituent (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 should have. The share is capped; so 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 determine the optimum proportion in each case on the basis of his specialist knowledge, if necessary with the aid of simple preliminary tests.

The other essential constituent of the coating material of the invention is 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

SiRt (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, for example, methyl, ethyl, propyl and butyl groups; Alkenyl groups, in particular with 2 to 4 carbon atoms, such as 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, such as phenyl and naphthyl grapppen. 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 carbon atoms, such as e.g. Methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, tert-butoxy and sec-butoxy groups; alkoxy-substituted alkoxy groups, e.g. beta methoxy ethoxy groups; Acyloxy groups, in particular with 1 to 4 carbon atoms, e.g. Acetoxy and propionyloxy groups; and alkylcarbonyl groups such as e.g. Acetyl groups.

Particularly preferred hydrolyzable groups R are those which have no substituent and give aromatics-free hydrolysis products with a low molecular weight, e.g. 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 and four, 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 grapppen 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.

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 adding the amount of water to 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 the presence of hydrolysis - And condensation catalyst, however, in the 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 a preferably 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 Methoxypropylacetate and / or 2-ethoxyethanol (ethyl glycol) or a ketone such as acetone or methyl ethyl ketone.

If appropriate, metal compounds and / or metal oxides 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 and / or TiO ₂ .

Examples of suitable metal compounds are hydrolyzable metal compounds (B2) of the general formula II

MR _n (II).

In the general formula II, the variable M stands for aluminum, titanium or zirconium, but in particular 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. It is advantageous here if in the case of aluminum at least two, in particular three, and in the case of titanium or zirconium, three, in particular four, hydrolyzable groups are present.

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 (B2) which is used with very particular preference is accordingly aluminum tris-sec-butoxide.

The molar ratio of metal M to silicon can be varied widely and depends primarily on the scratch resistance and hardness to be adjusted in the sol-gel coatings according to the invention. In general, the replacement of part of the silicon by aluminum in particular can increase the scratch resistance of the sol-gel coatings according to the invention. In particular, the molar ratio M: Si can be 1:10 to 1: 1.5, preferably 1: 6 to 1: 3.

Proton- or hydroxyl-ion-releasing compounds and amines are suitable as hydrolysis and condensation catalysts. Specific examples are organic or inorganic acids, such as hydrochloric acid, sulfuric acid,

Phosphoric acid, formic acid or acetic acid as well as organic or inorganic bases such as ammonia, alkali or alkaline earth metal hydroxides, e.g.

Sodium, potassium or calcium hydroxide, and amines soluble in the reaction medium, e.g. lower alkylamines or alkanolamines. Here are volatile

Acids and bases, especially hydrochloric acid, acetic acid, ammonia or

Triethylamine particularly preferred.

The precondensation is carried out so far that the resulting base lacquer (B) still has a liquid consistency. It preferably has a solids content of less than 80% by weight, particularly preferably less than 60% by weight and in particular less than 40% by weight.

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 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. The third essential component of the coating material of the invention is the additive solution (C).

It contains at least one ethylenically unsaturated compound (cl) which has at least one epoxy group. An example of a suitable compound (cl) is glycidyl (meth) acrylate.

Furthermore, it contains as component (c2) at least one silane (B1) with at least one non-hydrolyzable group R which has at least one epoxy group. An example of a suitable compound (c2) is 3-glycidyloxypropyltrimethoxysilane.

Last but not least, it contains at least one adduct (c3) 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 acid anhydride. An example of a suitable silane (B1) is 3-aminopropyltriethoxysilane. Examples of suitable dicarboxylic anhydrides are maleic anhydride and itaconic anhydride.

Components (cl), (c2) and (c3) 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 (C) is preferably below 80% by weight, preferably below 60% by weight and in particular below 50

% By weight.

The proportion of additive solution (C) in the coating material of the invention can also vary widely. The person skilled in the art can 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 20, preferably 10 to 15 and in particular 11 to 14% by weight of the acrylate copolymer solution (A), 40 to 85, preferably 45 to 80 and in particular 50 to 75% by weight. % of the base lacquer (B) and 0.5 to 3, preferably 1 to 2 and in particular 1.2 to 1.7% by weight of the additive solution (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

I to 10:30 to 60: 1

- preferably 2 to 8: 35 to 55: 1 and

in particular 2.5 to 6: 40 to 50: 1

to stand by each other.

The coating material of the invention may further contain at least one hardener (D). Examples of suitable hardeners (D) are quaternary ammonium compounds such as tetraalkylammonium salts, in particular tetramethylammonium iodide. The hardener (D) can preferably be contained in the coating material according to the invention in an amount of 0.001 to 1% by weight.

The coating material of the invention can furthermore contain relatively large amounts of preferably non-aromatic solvents as component (E). This is particularly the case when particularly thin sol-gel Coatings are to be made. 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 of the invention can contain customary and known paint additives (F). Suitable are all paint additives (F) which do not adversely affect the property profile 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

Light stabilizers such as UV absorbers;

- radical length;

Crosslinking catalysts;

Slip additives;

Polymerization inhibitors;

Defoamers;

- 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, alkanesulfonic 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;

film-forming aids such as cellulose 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 silicates, 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,

Polyvinylpyrrolidone, styrene-maleic anhydride or

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

Further examples of suitable additives (E) 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 are to be produced, ie coatings with a thickness of <5 μm, it is advisable to choose a solids content of less than 20% by weight.

The production of the coating material according to the invention has no special features, 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 the customary manner 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 present the base lacquer (B) in order to then add the remaining constituents one after the other. It has proven useful here to add the acrylate copolymer solution (A) before the additive solution (C). If a solvent (E) is used, it is advantageously added after the addition of the acrylate copolymer solution (A) and before the addition of the additive solution (C). If paint additives (F) are used, they are advantageously added after the addition of the acrylate copolymer solution (A). The hardener (D) is advantageously added last.

The coating materials of 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 case of plastic, it can be a so-called hydro grandier rank. in the In the case of metal, the substrate can also have been subjected to a surface treatment, for example an electroplating line or a phosphating line or anodizing line. Furthermore, an electro dip coating and a filler may be present on the metal substrate as a grandiose rank.

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 cured, 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. The coating materials of the invention can also be cured with medium IR radiation. This makes it possible to coat only parts of substrates or single-layer or multi-layer painting rods 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 the advantageous use of the coating materials according to the invention possible 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 above-mentioned ungrounded or primed substrates in order to then form a scratch-resistant sol-gel coating according to the invention after curing. In this way, substrates as they are usually used for the manufacture of vehicles, other components and devices, such as radiators or containers, or furniture is made scratch-resistant.

However, the particular advantages of the coating materials according to the invention are particularly evident when they are used for coating single-layer or multi-layer coating compositions with the sol-gel coatings according to the invention.

Accordingly, the coating materials according to the invention are suitable for the coating of single-layer or multi-layer lacquering coats, in particular single-layer or multi-layer effect and / or color-imparting lacquer coats such as are customary in the fields of automotive OEM coats, automotive refinish coats, industrial lacquer coats, including container coatings, plastic lacquer coats and furniture lacquer coats and are known.

Examples of single-layer paint coats of this type are the solid-color top coats described at the outset, known from automotive primer coats and car refinish coats, in particular those based on the two-component (2K) single-coat lacquers, or clear, transparent lacquer coats based on the clear coats described below, in particular the one-component (LC). Clearcoats, two-component (2K) or multi-component (3K, 4K) clearcoats, powder clearcoats and UV-curable clearcoats.

Examples of multi-layer paint coats are the paint coats, which have an effect and / or color-imparting base coat layer, in particular one based on a water-based paint, and a clear coat layer, in particular based on a one-component (IC) clear coat, two-component (2K) or

Multi-component (3K, 4K) clearcoat, powder clearcoat, powder slurry clearcoat or UV-curable clearcoat, especially a two-component (2K) - or Multi-component (3K, 4K) clear varnish, are included and are produced in the context of the automotive painting process using the wet-on-wet process or in the context of car repair painting.

The coating materials of the invention are particularly outstandingly suitable, in particular, for coating multi-layer coating oranges of this type.

Examples of suitable waterborne basecoats and the corresponding multi-layer painting rods can be found in the patents EP-A-0 089 497, EP-A-0 256 540, 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.

When using two-component (2K) undercoat lacquers or one-component (1K) clearcoats, two-component (2K) - or

Multi-component (3K, 4K) clearcoats, powder clearcoats and UV-curable clearcoats, especially two-component (2K) - or

Multi-component (3K, 4K) clearcoats, for the production of single-layer or multi-layer coatings, there is the further significant advantage that not only the coating materials of the invention are suitable for the production of the sol-gel coatings, but also conventional sol-gel clearcoats if the said lacquers are partially cured after their application and before the sol-gel clear lacquers are applied. After that, the said lacquers are fully cured together with the sol-gel clear lacquers. This procedure according to the invention results in a particularly good adhesion between the layers of paint and the sol-gel coatings. Particularly excellent results are obtained if the coating materials of the invention are used in the process according to the invention.

Examples of suitable one-component (IC), two-component (2K) or multicomponent (3K, 4K) clearcoats are known, 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.

One-component (IC) clearcoats are known to contain binders and crosslinking agents containing hydroxyl groups, 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 allophanate groups and optionally carbamate and or allophanate-modified aminoplast resins as crosslinking agents.

Two-component (2K) or multicomponent (3K, 4K) clearcoats contain, as is known, essential constituents of hydroxyl group-containing binders 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 binders containing epoxy groups 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.

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.

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-functional ones

(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 siractor units.

However, multilayer clear lacquer layers can also be used, such as a clear lacquer layer based on hydroxyl groups

Binders and blocked polyisocyanates and aminoplasts as crosslinking agents, which lie directly on the waterborne basecoat and over which contains a further clear lacquer layer based on binders containing carbamate and / or allophanate groups and aminoplasts as crosslinking agents.

The sol-gel coatings according to the invention, which are preferably produced from the coating materials according to the invention by the process according to the invention, are notable for excellent scratch resistance with very good adhesion, even after exposure to condensation water. The appearance is also very good. The method according to the invention is therefore particularly suitable for painting vehicle bodies, in particular automobile bodies, with multi-layer paint bars, for industrial paint shops, including container coatings, and for furniture paint shops.

Examples

Manufacturing example

The preparation of the sol-gel clear coat 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 4.1 parts of 3-glycidyloxypropyltrimethoxysilane were placed in a suitable reaction vessel under nitrogen 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 kept at this temperature for 2 hours. Then 70 parts of the reaction mixture were distilled off azeotropically at 85 ° C. After cooling to room temperature, the reaction mixture was 5 parts methoxypropylacetate and 0J parts of BYK® 301 (leveling agent from BYK) were added. This resulted in master varnish 1 with a theoretical solids content of 37% by weight and an experimentally determined solids content of 46.9% by weight (1 hour / 130 ° C.). The solids content was set at 40.3% by weight for the production of the sol-gel clearcoat 4b.

2. The preparation of an acrylate copolymer for modifying the sol-gel clearcoat (solution for organic modification 2)

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. In a second monomer feed vessel, 3.810 parts of hydroxyethyl acrylate, 1.831 parts of acrylic acid and 0.916 parts of ethoxyethyl propionate were introduced. 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 evenly into the reactor during 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 evenly into the reactor over four hours and 30 minutes, starting with the initiator feed five minutes before the first monomer feed. After the feeds had ended, 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 were reached. After that it was Ethoxyethyl propionate was distilled off in vacuo at 100 ° C. until a solids content of 81% by weight (15 minutes / 180 ° C.) 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 butyl glycol was adjusted to a solids content of 20% by weight, and the solution for organic modification 2 resulted.

The preparation of an additive solution

15 parts of ethyl glycol, 2 parts of 2,3-epoxypropyl methacrylic acid (glycidyl methacrylate), 7.5 parts of 3-glycidyloxypropyltrimethoxysilane, 0.5 part of an adduct of maleic anhydride and 3-aminopropyltriethoxysilane and 0J part of azodicarboxylic acid diamide (GenitronR) were stirred with AZDN - M mixed together at 100 ° C for six hours. The additive solution 3 with an experimentally determined solids content of 40% by weight (15 minutes / 180 ° C.) resulted.

The adduct itself was prepared by reacting 220 parts of 3-aminopropyltriethoxysilane and 100 parts of maleic anhydride.

The preparation of the sol-gel clearcoats 4a and 4b according to the invention

4.1 The sol-gel clear coat 4a

The sol-gel clearcoat 4a was obtained by adding 14.77 to 61.2 parts of the base coat 4 (46.9% by weight in ethyl glycol) with stirring Parts of the organic modification solution 2, 20.8 parts

Methoxypropylacetate, 0.014 parts BYK® 301, 1.57 parts of additive solution 3, 0.8 parts Tinuvin® 384 and 0.6 parts Tinuvin® 123 (light stabilizer from Ciba-Geigy) were mixed together. 7.0 parts of tetramethylammonium iodide solution (3% in methanol water 1: 1) were added to the resulting mixture. The resulting sol-gel clearcoat 4a was stirred at room temperature for 30 minutes. It had a solids content of 32% by weight (15 minutes / 180 ° C.). Sol-gel clearcoat 4a was used for the production of a sol-gel coating on a one-layer coating system based on a two-component (2K) undercoat (example 1).

4. 2 The Sol-Gel Clear Coat 4b

The sol-gel clearcoat 4b was obtained by adding 11.77 parts of the organic modification solution 2, 14.89 parts to 71.3 parts of the base coat 4 (40.3% by weight in ethyl glycol) with stirring Methoxypropylacetate, 0.47 parts BYK® 301 and 1.57 parts of additive solution 3 were added. The resulting sol-gel clearcoat 4b was used for the production of a sol-gel coating on a multilayer coating with a clearcoat layer based on a commercially available two-component (2K) clearcoat (example 2).

example 1

The production of a sol-gel coating according to the invention on a single-layer coating

Steel panels coated with a commercially available electrocoat (electrocoat with a layer thickness of 18-22 μm) were first applied and burned in with a cup gun using a commercially available filler from BASF Coatings AG. The result was a filler layer with a layer thickness of 35 to 40 μm. A commercially available two-component (2-component) uni topcoat (AK66-1110 Ral 9005 black from BASF Coatings AG) was applied to the filler layer and predried for 15 minutes at 50 ° C. and partially cured.

After the panels had cooled, the sol-gel clear lacquer 4a was applied. The solid-color topcoat and the sol-gel clearcoat were then cured together at 90 ° C. for 4 hours.

The result was a coating with a solid-color lacquer layer with a thickness of 45 μm and the sol-gel coating according to the invention with a thickness of 8 μm. The paint was free of cracks and made a very good overall optical impression.

Example 2

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 dip coat with a layer thickness of 18 - 22 μm). The result was a filler layer with a layer thickness of 35 to 40 μm. A green metallic water-based paint (Ecostar ^R jungle green from BASF Coatings AG) was then applied in the same way to the filler and predried at 80 ° C. for 10 minutes. After the panels had been cooled, a layer of a commercially available two-component (2K) clearcoat (FF95-0111 from BASF) was applied Coatings AG) applied and pre-dried for 10 min at 80 ° C and partially cured.

After the coated sheets had cooled, the sol-gel clearcoat 4b according to the invention was applied in accordance with the preparation example. The water-based lacquer layer, the clear lacquer layer and the sol-gel clear lacquer layer were then cured together at 150 ° C. for 30 minutes.

The result was a multilayer coating with a basecoat layer with a thickness of 15 μm, a clear lacquer layer with a thickness of 44 μm and the sol-gel coating according to the invention with a thickness of 8 μm. The paint shop was free of cracks and made a very good overall visual impression.

Example 3

Testing the properties of the sol-gel coatings according to the invention of Examples 1 and 2

3.1 Liability of the sol-gel coating

Table 1 gives an overview of the tests carried out and the results obtained.

Table 1:

Adhesive strength of the sol-gel coatings according to the invention

Test methods example

1 2 Scratch test according to DBL 7399 [grade 0 to 5] 0 0

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

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

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

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

The results in Table 1 demonstrate the excellent adhesion of the sol-gel coatings according to the invention to the respective coating rods.

3.2 The scratch resistance of the sol-gel coating

3.2.1 After the brush test

For this test, the test panels were stored at room temperature for at least 2 weeks after application of the paints 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, the however, with regard to the weight used (2000 g instead of the 280 g mentioned there), was assessed as follows:

In the test, the paint surface was damaged with a sieve fabric that was loaded with a mass. The screen fabric and the varnish surface were wetted liberally 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 cloth (No. 11, 31 μm mesh size, Tg 50 ° C.) (4.5 x 2.0 cm, wide side perpendicular to the scratch direction). The coating weight is 2000 g.

Before each test, the screen fabric was renewed, the direction of the mesh was parallel to the scratch direction. 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 that the sol-gel coatings of the invention were not scratched at all.

3.2.2 After the sand test

In addition, the scratch resistance was determined after the sand test. For this purpose, the paint surfaces were loaded with sand (20g quartz-silver sand 1.5-2.0 mm). The sand was placed in a beaker (floor cut off flat), which was firmly attached to the test panel. The same test panels as described above in the brush test were used. The table with the cup and the sand was shaken by means of a motor drive. The movement The loose sand caused damage to the paint surface (100 double strokes in 20 s). After exposure to sand, the test area was cleaned of abrasion, carefully wiped under a cold water jet and then dried with compressed air. The gloss was measured according to DIN 67530 before and after damage.

It was found that the gloss caused by the load

in Example 1 only by 9 gloss units and

in Example 2 only decreased by 13 gloss units,

which is further evidence of the extraordinarily high scratch resistance of the sol-gel coating according to the invention.

3.3.3 According to Amtec

The scratch resistance was determined in Example 1 by Amtec. As a result of the load, the gloss decreased from the initial value 68 by only 5 gloss units, which further underpins the high scratch resistance of the sol-gel coating according to the invention.

3.4 Chemical resistance

3.4.1 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 Examples 1 and 2 define the damage caused by sulfuric acid,

Exposed to water, pancreatin and tree sap. For this purpose, the test substances were spaced one segment width apart (setting the Gradients applied to 30 - 75 ° C [1 ° C per heating segment]). After storage of 72 stonde 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 Table 2.

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

Test substance Example 1 Example 2

1st marking 1st marking at ° C at ° C

Sulfuric acid 1% 61 55

Distilled water > 75> 75

Pancreatin <50 <50

Tree resin> 75> 75

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

3.4.2 After the MEK test The solvent resistance of the sol-gel coatings of Examples 1 and 2 according to the invention were tested in accordance with the specification of the MEK test well known to the person skilled in the art. Even after 200 double strokes with cotton balls soaked in methyl ethyl ketone, no damage was seen.

3.5 stone impact test

The VDA stone impact test known to the experts under multi-impact load (2 x 500 grams / 2 bar) provided a characteristic value of 3 and a degree of rust of 2 in both Examples 1 and 2. Accordingly, the sol-gel coating according to the invention, together with the single-layer coating, proved to be (Example 1) and the multi-layer painting line (Example 2) as sufficiently stable against stone chips.

3.6 Erichsen deepening

The Erichsen depth according to DIN EN ISO 1520: 1995-04 was 0.5 mm (example 1) or 0.4 mm (example 2).

Claims

claims

1. Sol-gel coating material containing

(A) an acrylate copolymer solution containing at least one

al) at least one essentially acid-free (meth) acrylic acid ester,

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-carrying ethylenically unsaturated monomer;

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 grappa;

and

(C) containing an additive solution

c3) at least one adduct 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 acid anhydride.

2. The sol-gel coating material according spoke 1, characterized in that it, based in each case on its total amount, 5 to 20, preferably 10 to 15 and in particular 11 to 14 wt .-% of the acrylate copolymer solution (A), 40 to 85 , preferably 45 to 80 and in particular 50 to 75% by weight of the base coating (B) and 0.5 to 3, preferably 1 to 2 and in particular 1.2 to 1.7% by weight of the additive solution (C).

. The sol-gel coating material according to claim 1 or 2, characterized in that the solids contents of the components (A), (B) and (C) in a weight ratio of (A): (B): (C) from

1 to 10: 30 to 60: 1

preferably 2 to 8: 35 to 55: 1 and

in particular 2.5 to 6: 40 to 50: 1

to stand by each other.

4. The sol-gel coating material according to one of claims 1 to 3, characterized in that the base lacquer (B) at least one hydrolyzable metal compound of the general formula II

MR _n (IT),

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; contains.

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

the non-hydrolyzable Grappen R alkyl groups, in particular with 1 to 4 carbon atoms; Alkenyl 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 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 Grappen 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 Grappen R methyl, ethyl, propyl, butyl vinyl, 1-propenyl, 2-propenyl, butenyl, acetylenyl,

Are propargyl, phenyl and / or and naphthyl groups.

7. The sol-gel coating material according to 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 it is a sol-gel clear coat.

9. The use of the sol-gel coating material according to any one of claims 1 to 8 for the production of scratch-resistant sol-gel coatings, in particular for single-layer or multi-layer coating oranges.

10. The use of the sol-gel coating material according to spoke 9, characterized in that it is cured single-layer or multi-layer coating rods.

11. The use of the sol-gel coating material according to claim 9 or 10, characterized in that it is in the painting rods to automotive painting rods, auto repair painting rods, industrial painting rods, including container coatings, plastic coating rods and furniture lacquers.

12. A method for producing scratch-resistant sol-gel coatings by applying and curing sol-gel coating materials on ungranded or primed substrates or ungranded or primed substrates, which are provided with a single-layer or multi-layer coating, characterized in that a sol -Gel- coating material according to one of claims 1 to 8 used.

13. Process for the production of scratch-resistant sol-gel coatings by application and curing of sol-gel coating materials on ungrounded or sized substrates, which are provided with a single-layer or multi-layer painting, characterized in that before the application of the sol-gel coating material

(il) a single-layer painting line based on a

One-component (1K) clearcoat, two-component (2K) or multi-component (3K, 4K) clearcoat, powder clearcoat or UV-curable clearcoat,

(i2) a multi-layer effect and / or color-imparting coating with a top layer based on a one-component (IC) clear coat, two-component (2K) or multi-component (3K, 4K) clear coat, powder clear coat or UV-curable clear coat, in particular one One-component (lK) clearcoat, two-component (2K) - or multi-component (3K, 4K) -

Clear coats, or

(i3) a one-layer effect and / or color-imparting coating system based on a two-component (2K) uni top coat

applied and partially cured.

14. The method according spoke 13, characterized in that one uses a sol-gel coating material according to one of claims 1 to 8.

15. The method according to any one of claims 12 to 14, characterized in that the applied sol-gel coating material is cured by irradiation with medium IR radiation.

16. The method according to any one of claims 12 to 15, characterized in that it is in the Lackierangen to Automotive OEM Lackangen, Autoreparatorlackierangen, industrial Lackierangen, including container coatings, and Möbelackierangen.

17. Sol-gel coatings, producible from a sol-gel coating material according to one of claims 1 to 8 and / or by the method according to one of claims 12 to 16.

18. Substrates containing at least one sol-gel coating according to claim 17.