EP0424412A1

EP0424412A1 - Hydroxyl group-containig copolymerizates based on vinyl ester monomers, vinyl aromatic monomers and hydroxyalkyl ester monomers, process for producing them and their use in coating agents

Info

Publication number: EP0424412A1
Application number: EP19890907137
Authority: EP
Inventors: Werner Alfons Jung; Udo Vorbeck
Original assignee: BASF Lacke und Farben AG
Current assignee: BASF Farben und Fasern AG
Priority date: 1988-07-07
Filing date: 1989-06-19
Publication date: 1991-05-02
Also published as: DE58902136D1; DE3823005A1; ES2052820T3; CA1328146C; EP0349818A1; EP0349818B1; WO1990000570A1; BR8907527A; ATE79888T1; US5322897A

Abstract

The invention concerns hydroxyl group-containing copolymerizates with an OH number of 50 to 200 mg KOH/g and a mean molecular weight (numerically) of 1500 to 6000, which can be produced by radical solution polymerization at temperatures of 130 to 200 DEG C from 5 to 25 wt.% of vinyl ester monomers, 10 to 50 wt.% of vinyl aromatic monomers, 10 to 50 wt.% of hydroxyalkyl ester monomers and possibly other monomers. The vinyl ester monomer is taken and the other monomers are added within a monomer addition time-interval equal for all monomers, as follows: i) the quantity of acrylate monomers added per unit time is constant; ii) the quantity of vinyl aromatic monomer added during the first third of the monomer addition time-interval is equal to 15 to 30 wt.%, preferably 18 to 26 wt.%, in the second third 25 to 40 wt.%, preferably 30 to 38 wt.%, and in the third third 35 to 60 wt.%, preferably 40 to 50 wt.%, referred to the total amount of vinyl aromatic monomer. Also described are processes for producing the copolymerizates and their use in coating agents.

Description

Copolymers containing hydroxyl groups based on vinyl ester, vinyl aromatic and hydroxyl alkyl ester monomers, processes for their preparation and their use in coating compositions

The invention relates to copolymers which contain hydroxyl groups and are soluble in organic solvents and can be prepared by means of free radical solution polymerization of vinyl ester, vinyl aromatic and hydroxyalkyl ester monomers and, if appropriate, further copolymerizable monomers, processes for their preparation and their use in coating compositions. Hydroxyl group-containing acrylate polymers are well known, as are coating compositions which contain these polymers as an essential binder component (cf. for example EP-A-103 199, EP-A-52 233, EP-B-39 797, EP-A -136 667, EP-B-64 338).

It is also known that problems arise in the production of acrylate copolymers if monomers with a reactivity which is very different from that of acrylate monomers, such as e.g. Vinyl esters of branched in the dL position, - aliphatic monocarboxylic acids with 5 to 15 carbon atoms, are used. In these

In some cases it is difficult to obtain uniform, ie statistically homogeneously distributed copolymers. One solution to this problem is the process for copolymerizing differently reactive monomers described in US Pat. No. 4,039,734, in which at least part of the reactive monomer is continuously added to the reaction mixture in such an amount that the relative monomer ratio remains constant. The amount of monomers required for this is determined with the help of the heat of reaction released.

In the process described in DE-PS 20 32 647, uniform vinyl ester, vinyl aromatic and hydroxyacrylate copolymers are correspondingly obtained by gradually adding the individual monomers. In this process, the total amount of vinyl ester is introduced together with 5 to 15% by weight of the total amount of vinyl aro aten and the total amount of the other hydroxy-functional monomers and unsaturated carboxylic acids. The remaining amount of monomers is then either gradually added as a whole or metered in such that the addition of the OH and COOH monomers takes longer than the vinyl aromatic feed. A disadvantage of this process is the very high residual monomer content (ie the amount of unreacted starting monomer, expressed in% by weight, based on the total amount of this monomer originally used) of up to 40% by weight of vinyl ester when using one high vinyl aromatic content of up to 50% by weight and the associated toxicity problems. Another disadvantage with regard to the solvent pollution of the environment when drying the paint films is the high solvent content of the coating agents caused by the high viscosity of the binder solutions. In addition, there is a risk of turbidity in the case of polymer solutions with a higher solids content, which can only be eliminated by adding further solvents. Also the technical information in English "VeoVa poly ers LR-40 and LR-2041 for water-thinnable paints" from Shell describes such copolymers containing vinyl esters, vinyl aromatics and hydroxyalkyl esters, but these likewise have the disadvantages just mentioned.

Finally, some mass polymerization processes for the production of copolymers containing vinyl esters are also known, in which the total amount of the vinyl ester is also heated, possibly with a part of the total amount of the other monomers and optionally the initiator, and then the remaining amount of monomers and initiator is gradually added (see, for example, DE-PS 24 22 043 and DE-OS 26 15 101). In these processes, it is possible to completely incorporate the vinyl ester (residual monomer content <10% by weight), but the copolymer solutions obtained in this way are cloudy after dissolving the polymer composition and are not suitable for coating formulations.

The invention was therefore based on the object of making available copolymers containing hydroxyl groups on the basis of vinyl ester, vinylaromatic and hydroxyalkyl ester monomers and, if appropriate, further copolymerizable monomers which can be prepared by a simple process which can also be used when using a high vinyl aromatic content of up to 50% by weight, based on the total amount of monomers, have a low residual monomer content (-tlO% by weight) and give clear solutions. The coating compositions produced using these copolymers should have the highest possible solids content with a viscosity of 16 to 20 s, which is favorable for processing, measured in the discharge cup according to DIN 4, show good pigmentability and, in particular, coatings with good technological properties ¬ particularly good hardness. Surprisingly, this object is achieved by a hydroxyl-containing copolymer (A) which can be prepared by means of free-radical solution polymerization and which is characterized in that the copolymer (A) has an OH number of 50 to 200 mg KOH / g, preferably 70 to Has 150 mg KOH / g and an average molecular weight (number average) of 1500 to 6000 and can be produced by radical solution polymerization at temperatures from 140 to 200 ° C, from

a,) 5 to 25 wt .-%, preferably 10 to 19 wt .-%, of one or more Vinylester of monocarboxylic acids s, preferably in Vinylester of "c -Stel¬ lung branched monocarboxylic acids having 5 bis 15 ^'C Atoms per molecule,

a) 10 to 50% by weight, preferably 20 to 45% by weight, of one or more vinylaromatic hydrocarbons,

a ₃ ) 10 to 40% by weight, preferably 15 to 35% by weight, of one or more hydroxyalkyl esters, β-unsaturated carboxylic acids,

a.) 0 to 40% by weight of other ethylenically unsaturated, copolymerizable monomers, the sum of components a to a. each gives 100% by weight, whereby

1.) at least 60% by weight, preferably 100% by weight, of the total amount of component a are introduced,

2.) the components a ~ to a. and the rest of component a, if present, within a monomer of the same length for all components. dosing period so that

i) the amount of component a added per unit of time remains constant or decreases within the monomer addition period,

ii) the amount of components a- and a. remains constant within the monomer addition period and

iii) the amount of component a ₂ added within the first third of the monomer addition period 15 to 30% by weight, preferably 18 to 26% by weight, of the total amount of component a_, within the second third 25-40% by weight .-%, preferably 30 to 38% by weight and within the last third 35-60% by weight, preferably 40 to 50% by weight, of the total amount of component a_.

As component a, vinyl esters of monocarboxylic acids, preferably vinyl esters of monocarboxylic acids with 5 to 15 carbon atoms per molecule branched in the t position, are used. 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 triene, propylene tetramer and diisobutylene. The vinyl esters can can also be produced from the acids in a manner known per se, e.g. B. by allowing the acids to react with acetylene.

Because of their good availability, vinyl esters of saturated aliphatic are particularly preferred

Monocarboxylic acids with 9 - 11 C atoms, which are attached to the -C atom. are branched. The vinyl ester of p-tert-butylbenzoic acid is also particularly preferred. Examples of other suitable vinyl esters are vinyl acetate and vinyl propionate.

The amount of components a. is 5 to 25% by weight, preferably 10 to 19% by weight.

Component a ₂ is a monovinylaromatic compound. It preferably contains 8 to 9 carbon atoms per molecule. Examples of suitable compounds are styrene, vinyltoluenes, ch-methylstyrene, chlorostyrene, o-, m- or p-methylstyrene, 2,5-dimethylstyrene. p-methoxystyrene, p-tert. -Butyl styrene, p-dimethylaminostyrene, p-acetamidostyrene and m-vinylphenol. Vinyl toluenes and in particular styrene are preferably used. The amount of component a ~ is 10 to 50% by weight, preferably 20 to 45% by weight.

As component a ₃ , hydroxyalkyl esters of d ^ -unsaturated carboxylic acids with primary or secondary hydroxyl groups are suitable. If a high reactivity of the acrylate copolymer is desired, only hydroxyalkyl esters with primary hydroxyl groups can be used; if the polyacrylate is to be less reactive, only hydroxyalkyl esters with secondary hydroxyl groups can be used. Mixtures of hydroxyalkyl esters with primary hydroxyl groups and hydroxyalkyl esters with secondary hydroxyl groups can of course also be used. Examples of suitable hydroxyalkyl esters ei, (B-unsaturated carboxylic acids with primary hydroxyl groups are hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyamyl acrylate, hydroxyhexyl acrylate, hydroxyoctyl acrylate and the corresponding methacrylates. Examples of suitable hydroxyalkyl esters with a secondary hydroxyl group are 2-hydroxypropyl groups with a secondary hydroxyl group "Hydroxybutyl acrylate, 3-hydroxybutyl acrylate and the corresponding methacrylates. Of course, the corresponding esters of other ot _/ β-unsaturated carboxylic acids such as crotonic acid and isocrotonic acid can of course also be used.

Advantageously, component a _{3 can be} at least partially a reaction product of one mole of hydroxyethyl acrylate and / or hydroxyethyl methacrylate and an average of two moles of ε-caprolactone.

As component a. a reaction product of acrylic acid and / or methacrylic acid with the glycidyl ester of a carboxylic acid with a nem tertiary «carbon atom can be used. Glycidyl esters of strongly branched monocarboxylic acids are available under the trade name "Cardura". The reaction of acrylic acid or methacrylic acid with the glycidyl ester of a carboxylic acid with a tertiary carbon atom can take place before, during or after the polymerization reaction. Care must be taken that the acid number of the finished polyacrylate is in the range from 5 to 30 mg KOH / g, preferably 8 to 25 mg-K0H / g.

Component a_ is used in an amount of 10 to 40% by weight, preferably 15 to 35% by weight

0 to 40% by weight of other ethylenically unsaturated, copolymerizable monomers (component a.) Can also be used to build up the copolymer (A) containing hydroxyl groups. The selection of these monomers is not particularly critical. However, care must be taken to ensure that the incorporation of these monomers does not lead to undesirable properties of the copolymer. This is how component a is selected. largely according to the desired properties of the curable composition in terms of elasticity, hardness, compatibility and polarity. Preferred as component a. Alkyl esters of olefinically unsaturated carboxylic acids used. Examples include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, Isoamyl (meth) acrylate, hexyl (meth ^ acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth), acrylate, octyl (meth) acrylate, 3,5,5-trimethylhexyl (meth) acrylate, Decyl (meth) acrylate, dodecyl (meth) acrylate, hexadecyl (rneth) acrylate, octadecyl (meth) acrylate, octa-decenyl (eth) acrylate and the corresponding esters of maleic, fumaric, croton and iso - Crotonic, vinyl acetic and itaconic acid. Suitable as component a. are also other ethylenically unsaturated compounds, such as alkoxyethyl acrylates, aryloxyethyl acrylates and the corresponding methacrylates, such as butoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate; unsaturated carboxylic acids such as, for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid and half esters of maleic and fumaric acid and mixtures thereof; unsaturated compounds with tertiary amino groups such as N, N'-diethylaminoethyl methacrylate, 2-vinylpyridine, 4-vinylpyridine, vinylpyrroline, vinylquinoline, vinylisoquinoline, N, N'-dimethylaminoethyl vinyl ether and 2-methyl-5-vinylpyridine; Compounds such as acrylonitrile, methacrylonitrile, acrolein and methacrolein.

The polymerization of the mono components a-. to a. is preferably carried out in the absence of oxygen, for example by working in a nitrogen atmosphere. The reactor is equipped with appropriate stirring, heating and cooling devices and with a reflux condenser in which volatile constituents, such as styrene, are retained. The polymerization reaction is conducted at temperatures from 130 to 200 ^β C, preferably 150-180 C ^β conducted tion controllers using polymerization initiators and optionally Polymerisa¬. Suitable free-radical initiators are organic peroxides, such as, for example, dibenzoyl peroxide, dicumyl peroxide, cumene hydroperoxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, 2,2-di-tert-butyl peroxybutane, tert-amyl perbenzoate, 1,3-bis (tert.-butylperoxyisopropyl) benzene, diisopropylbenzene monohydroperoxide and diacyl peroxides, such as, for example, diacetyl peroxide, peroxyketal, such as, for example, 2,2-di (tert.-amylperoxy) propane and ethyl-3,3-di- (tert.- amylperoxy) butyrate, thermolabile highly substituted ethane derivatives, for example based on silyl-substituted ethane derivatives and based on benzopinacol. Furthermore, aliphatic azo compounds, such as, for example, azobiscyclohexanenitrile, can also be used. Depending on the monomers used, however, when using azo compounds there is a risk of yellowing of the polymers which, depending on the intended use of the polymers, can be troublesome, so that in these cases other initiators must be used.

The amount of initiator is in most cases 0.1 to 5% by weight, based on the amount of monomers to be processed, but it can also be higher if necessary. The initiator, dissolved in part of the solvent used for the polymerization, is gradually metered in during the polymerization reaction. The initiator feed preferably takes about 1 to 2 hours longer than the monomer feed in order to also achieve a good effect during the post-polymerization phase. If initiators with only a low decomposition rate are used under the present reaction conditions, so it is possible to present the initiator.

The reaction is preferably carried out in the presence of polymerization regulators, since clouding of the polymer solutions can thus be avoided better. Mercapto compounds are preferably suitable as regulators, mercaptoethanol being particularly preferably used. Other possible regulators are, for example, alkyl ercaptane, e.g. t-Dodecyl mercaptan, octyl mercaptan, phenyl mercaptan, octyldecyl mercaptan, butyl mercaptan, thiocarboxylic acids, such as thioacetic acid or thiolic acid.

These regulators are used in an amount of up to 2% by weight, based on the amount of monomers to be processed. They are preferably dissolved in one of the monomer feeds and added with the monomers. The amount of regulator added is preferably constant over time.

The polymerization is carried out in a high-boiling, organic solvent which is inert towards the monomers used. Examples of suitable solvents are high-boiling alcohols, such as, for example, n-hexanol, 2-ethylhexanol, isooctyl alcohol, isononyl alcohol, isodecyl alcohol, isotridecyl alcohol, cyclohexanol, methylcyclohexanol, benzyl alcohol, methylbenzyl alcohol, tetrahydrofufuryl alcohol, 2,6-diacetone alcohol Dimethyl-4-heptanol, 4-methyl-2-pentanol, tridecanol; Glycols and glycol derivatives, such as, for example, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 1,4-butanediol, hexylene glycol, 2-ethylhexanediol-1,3, diethylene glycol, triethylene glycol, dipropylene glycol, methyl diglycol, ethyl diglycol, butyl diglycol, Hexyldiglycol, tripropylene glycol methyl ether, methoxytriglycol, ethylglycol acetate, butylglycol acetate, ethyl higher-boiling aliphatic and cyclo aliphatic hydrocarbons, such as various white spirits, mineral turpentine, tetralin and decalin. With certain monomer combinations (such as, for example, amino-functional plus carboxyl-functional monomers), only inert solvents, such as aromatic and aliphatic hydrocarbons or esters, should be used.

If the copolymers (1) containing hydroxyl groups are modified in a second stage, e.g. by reacting with compounds (B) which contain on average 0.8 to 1.5 free NCO groups and at least one tertiary amino group per molecule, this must be the case during the polymerization, ie preparation of the polymers (A) , Solvents used are of course also inert towards the compounds (B). It is essential to the invention that the copolymerization of components a. to a. is carried out as follows:

At least 60% by weight, preferably 100% by weight, of the total amount of component a _{1 to be used} together with part of the total amount of solvent to be used are initially introduced into the reactor and heated to the respective reaction temperature. As already described, the remaining amount of the solvent is preferably added gradually together with the catalyst. Any remaining amount of component a. as well as the other monomers (components a_, a ₃ and a ₄ ) are within a monomer addition period of the same length for all components (is generally

2 - 10 h, as usual for acrylate copolymerizations) to the component a. add as follows:

i) The amount of any component a. (ie the residual amount of component a. which was not initially introduced) remains constant or decreases within the monomer addition period, the last process variant being preferred. In the case of a constant addition amount, component a. preferably together with components a ₃ and a. added.

ii) The amount of the components added per unit of time is aa3 ,, and aa4 .. remains constant within the monomer addition period

iii) The amount of component a- added per unit of time is varied within the monomer addition period such that the total amount of component a added within the first third of the monomer addition period a ~ 15 to 30% by weight, preferably 18 to 26% by weight .-%, the total amount of component a_ is. Within the second third of the monomer addition period, a total of 25 to 40% by weight, preferably 30 to 38% by weight, and within the last third of the monomer addition period 35 to 60% by weight, preferably 40 to 50% by weight. -%, of the total amount of component a, the total of the addition amounts in the 1st, 2nd and 3rd thirds is 100% by weight. There are various possibilities for varying the amount of component a_ added per unit of time, the only thing that is decisive is that the amounts given in total in the respective third are adhered to. For example, there is the possibility of gradually changing the amount of component a_ added per unit of time. The number of stages at which the amount added is changed can be chosen as desired. For example, the amount added per unit of time of component a_ can only be increased at the beginning of the second and / or at the beginning of the third third. The amount added per unit of time then remains constant within the third. However, it is also possible to continuously change the amount of component a_ added per unit of time, in accordance with the limit of an infinite number of stages.

The addition of the components in the manner mentioned promotes, as is assumed, the copolymerization and reduces the homopolymerization of the individual components. In addition, copolymers with a very low residual monomer content are obtained which give clear solutions with a high solids content. The hydroxyl-containing copolymers (A) thus obtained have an average molecular weight (number average) of 1500 to 6000 and an OH number of 50 to 200 mg KOH / g, preferably 70 to 750 mg KOH / g and an amine number of 1 up to 10 mg KOH / g, preferably 1 to 5 mg KOH / g. 50% solutions of the copolymers according to the invention in butyl acetate typically have viscosities of 0.2 to 4 dPas at 23 ° C. Except by using tert. Monomers containing amino groups in the copolymerization can be tert. Amino groups are also introduced into the hydroxyl-containing copolymer (A) by reaction with compounds (B) which contain an average of 0.8 to 1.5, preferably 1, free isocyanate groups per molecule. This process is particularly preferred when the copolymers are to be used for the production of clearcoats.

The copolymers (A) are reacted with the compounds (B) in an isocyanatine solvent at temperatures of 10 to 100 ° C., preferably 50 to 80 ° C., if appropriate in the presence of organic tin compounds as catalysts, up to an NCO value of practically zero. The amount of compound (B) is chosen so that the resulting resin has an amine number of 1 to 10 mg KOH / g, preferably 1 to 5 mg KOH / g.

The compounds (B) used to introduce the tertiary amino group into the copolymer (A) are prepared by reacting diisocyanates or polyisocyanates with a stoichiometric deficit on a tertiary amine. Suitable for this implementation are tertiary amines of the general formula NR-RR-, where R. preferably denotes an alkanol radical or another hydroxyl-containing radical and may represent R- or R-alkyl or cycloalkyl radicals. Dialkylalkanolamines, such as, for example, dimethylethanolamine, diethylethanolamine and their higher homologs or isomers, are preferred. Suitable di- or polyisocyanates are, for example:

Aromatic isocyanates, such as, for example, 2,4-, 2,6-tolylene diisocyanate and mixtures thereof, 4, 'diphenylmethane diisocyanate, m-phenylene, p-phenylene, 4,4'-diphenyl, 1,5- Naphthalene, 1,4-naphthalene,, ^• -toluidine, xylylene diisocyanate and substituted aromatic systems, such as dianisidine diisocyanates, 4,4'-diphenyl ether diisocyanates or chlorodiphenylene diisocyanates and higher functional aromatic isocyanates, such as

1,3,5-triisocyanatobenzene, 4,4 ^, -, 4 "-triisocyanatetriphenylmethane, 2,, 6-triisocyanatotoluene and 4,4'-diphenyldimethylmethane-2,2 ', 5,5'-tetraisocyanate; cycloaliphatic isocyanates, such as 1,3-cyclopentane, 1,4-cyclohexane, 1,2-cyclohexane and isophorone diisocyanate; aliphatic isocyanates such as trimethylene, tetramethylene, pentamethylene, hexamethylene, trimethylhexamethylene-1,6-diisocyanate and Tris-hexamethylene triisocyanate.

Diisocyanates with different reactive isocyanate groups are preferably used, e.g. Isophorone diisocyanate.

The invention also relates to a process for the preparation of hydroxyl-containing copolymers (A) by means of radical solution polymerization, which is characterized in that

a) 5 to 25% by weight, preferably 10 to 19% by weight, of one or more vinyl esters of monocarboxylic acids, preferably vinyl esters of monocarboxylic acids branched in the - position with 5 to 15 Carbon atom per molecule,

a ₂ ) 10 to 50% by weight, preferably 20 to 45% by weight, of one or more vinylaromatic carbons

Hydrogens,

a.) 10 to 40% by weight, preferably 15 to 35% by weight, of one or more hydroxyalkyl esters of -t ^ unsaturated carboxylic acids,

a.) 0 to 40% by weight of other ethylenically unsaturated, copolymerizable monomers, the sum of components a to a. each gives 100% by weight.

at temperatures of 130 to 200 ^C C, preferably 150 to 180 ° C, to a copolymer (A) with an OH number of 50 to 200 mg KOH / g, preferably 70 to 150 mg KOH / g and an average molecular weight (number average ) from 1500 to 6000, where

2.) the components a_ to a. and any remaining component a. are metered in within a monomer addition period of the same length for all components in such a way that

i) the amount of component a added per unit of time. remains constant or decreases within the monomer addition period,

ii) the amount of added per unit of time Components a ₃ and a. within the

Monomer addition period remains constant and

(iii) the amount of. added within the first third of the monomer addition period

Component a. 15 to 30% by weight, preferably 18 to 26% by weight, of the total amount of component a_, within the second third 25-40% by weight, preferably 30 to 38% by weight and within the last third, 35-60% by weight, preferably 40 to 50% by weight, of the total amount of component a_.

Components a to a that can be used in this process. and the implementation of the process according to the invention have already been described in detail in connection with the copolymers (A) according to the invention, so that reference is made only to this description.

The present invention furthermore relates to coating compositions which contain the hydroxyl-containing copolymers according to the invention as a binder component. Suitable hardener components in these coating compositions are aminoplast resins, polyisocyanates and compounds containing anhydride groups. The crosslinking agent is added in such an amount that the molar ratio of the OH groups of the copolymer (A) to the reactive groups of the crosslinking agent is between 0.3 r 1 and 3: 1.

Aminoplast resins suitable as hardener components are preferably melamine and / or benzoguanamine resins. There are etherified melamine or benzoguanamine-formaldehyde condensation products. The compatibility of the resins with other film formers and solvents is influenced by the chain length of the etherification alcohol and the degree of etherification. The main etherification components are n- and isobutanol and methanol. Hexamethoxymethylmelamine resins are very important. However, they have the disadvantage that such combinations only harden at temperatures above 150 ° C. and that it is often necessary to add acidic catalysts. The resins produced with less formaldehyde and / or etherified with secondary or tertiary alcohols, on the other hand, crosslink e.g. T. already below 100 ° C. The corresponding urea and urethane resins can also be used.

The polyisocyanates used for crosslinking the copolymers A) are the same polyisocyanates which are also used for the preparation of the compound (B). For suitable examples, reference is therefore made to the description of compound (B). Furthermore, the polyisocyanates can also be linked to prepolymers with a higher molecular weight. Adducts of tolylene diisocyanate and trimethylolpropane, a biuret formed from 3 molecules of hexamethylene diisocyanate and the trimers of hexamethylene diisocyanate and 3,5,5-trimethyl-l-isocyanato-3-isocyanatomethylcyclohexane are to be mentioned here.

The amount of crosslinker used is chosen so that the ratio of the isocyanate groups of the crosslinker to the hydroxyl groups of component A) is in the range from 0.3: 1 to 3.5: 1. Combinations with polyisocyanates or resins bearing isocyanate groups crosslink quickly, even at room temperature.

However, the above-described ones can also be used, with conventional capping agents, such as Phenols, alcohols, acetoacetic acid esters, ketoxime and caprolactam, reacted isocyanates. These combinations are stable at room temperature and generally only harden at temperatures above 100 ° C. In special cases, e.g. when using acetoacetic acid esters for capping, crosslinking can also occur below 100 ° C.

Suitable hardeners are also compounds or resins which contain carboxylic acid anhydride groups and which react with the polymers according to the invention via ester formation. The curing temperature depends on the reactivity of the anhydride group contained in the combination partner. So it succeeds e.g. with polyfunctional compounds or resins, to provide coating compositions which crosslink at 80 to 120 ° C.

The coating compositions according to the invention can also contain customary auxiliaries and additives, such as leveling agents, silicone oils, plasticizers, such as phosphoric acid esters and phthalic acid esters, pigments and fillers, viscosity-controlling additives, matting agents, UV absorbers and light stabilizers. These coating compositions can be applied by spraying, flooding, dipping, rolling, knife coating or brushing onto a substrate in the form of a film, the film subsequently forming a firmly adhering coating is hardened.

The coating compositions of the invention are suitable

- if, through appropriate selection of the hardener component, low curing temperatures between 20 and 80 ° C can be used (see above) - for the refinish of motor vehicles and especially for use as a primer and filler material.

The invention is explained in more detail in the following examples. Unless expressly stated otherwise, all information on parts and percentages are by weight.

Polvisocvanatlnςnnri 1

The polyisocyanate solution 1 used in the examples consists of the following components:

33.3 parts of trimerized hexamethylene diisocyanate,

90% in a 1: 1 mixture of butyl acetate / solvent naphth

15.0 parts of trimerized isophorone diisocyanate,

70% in solvent naphtha ^

22.3 parts of butyl acetate

15.6 parts of butyl glycol acetate

3.5 parts of 3-methoxybutyl acetate

3.5 parts xylene

4.9 parts of a commercially available mixture monocyclic terpenes with a boiling range of 162 to 182 ° C

0.9 parts solvent naphth

1.0 part catalyst solution (1 part dibutyltin dilaurate, dissolved in 50 parts butyl acetate, 44 parts solvent naphth! ^ And 5 parts 3-methoxybutyl acetate)

Lacquer thinning α 1

The paint thinner 1 consists of the following components:

15 parts of xylene

13 parts of solvent naphth • ß-> 10 parts of a commercially available hydrocarbon mixture with a boiling range of 135 to 185 ° C and an aromatic content of approx. 16.5%. 50 parts butyl acetate 5 parts l-methoxypropylacetate-2 3 parts butylglycol acetate 2 parts 3-methoxybutyl acetate

2 parts of a commercial mixture of monoethylenically cyclic terpenes with a Siedebe¬ rich ^β of 162 to 182 C.

example 1

In a 4-liter stainless steel kettle with stirrer, reflux condenser and inlet devices, 201.6 parts of solvent naphthol (mixture of C3-C4-alkyl-substituted aromatics) and 264 parts of a commercially available are mixtures of vinyl esters of saturated aliphatic monocarboxylic acids with predominantly 10

C atoms that are branched on the e - C atom, submitted and heated to 170 ° C.

Weigh and mix in the monomer tank I:

120 parts of methyl methacrylate 216 parts of hydroxyethyl methacrylate 2.4 parts of dodecyl mercaptan

The following are weighed into the monomer tank II:

600 parts of styrene

The following are weighed and mixed into the initiator tank:

108 parts of solvent naphtha ^ 36 parts of di-tert. Butyl peroxide

The monomer tank I is metered in uniformly over the course of 4.5 hours. The monomer tank II is metered in over the course of 4.5 h so that in the first 90 min. 100 parts are metered in, 200 parts are metered in from the 91st to the 180th minute of the total running time and 300 parts of styrene are metered in during the remaining feed time. The temperature in the boiler is kept at 165-170 ° C during the run. After all feeds have ended, they are repeated within 1 hour

18 parts of solvent naphtha ⁰ 'and 6 parts of di-tert. Butyl peroxide dosed from the initiator tank. Thereafter, polymerization is continued for a further 2 hours at this temperature.

It is dissolved with 342 parts of butyl acetate. The solids content (1 h 130 ^C C) of this copolymer solution 1 is 71%, the viscosity (50% in ethyl glycol acetate) 0.85 dPa.s. (measured at 23 ° C).

The residual content of free vinyl ester monomer in the 71% polymer solution 1 was determined by means of gas chromatography. A residual content of 1.5% by weight was found. (This corresponds to a residual monomer content of 9.6% by weight, based on the total amount of vinyl ester monomer used.).

In a 4-liter stainless steel kettle with stirrer, reflux condenser and feed devices, 325.6 parts of Shellsol ^ (mixture of C 3 -C 4 alkyl-substituted aromatics) and 360.0 parts of a commercially available mixture of vinyl esters of saturated aliphatic monocarboxylic acid with predominantly 10 carbon atoms, which are branched on the «iC atom, presented. Weigh and mix in the monomer tank I:

252 parts of n-butyl acrylate

468 parts of hydroxyethyl methacrylate

144 parts of methyl methacrylate

36 parts of methacrylic acid

27 parts of mercaptoethanol The following is weighed into the monomer tank II:

540 parts of styrene

Weigh and mix in the initiator tank:

129.6 parts Shellsol A® 43.2 parts di-tert. Butyl peroxide

The initial charge is heated to 160-170 ° C. and the contents of monomer tank I and of the initiator tank are evenly metered into the boiler within 4.5 hours. The content of the monomer tank II is metered in over the course of 4.5 hours in such a way that 25% of the amount of styrene is added in the first 90 minutes, 35% of the amount of styrene from the 91st to the 180th minute and 40% of the amount of styrene in the remaining feed time. The following are then added from the initiator tank within 1 h:

13.5 parts Shellsol 4.5 parts di-tert. Butyl peroxide.

During the polymerization, the temperature is reduced to approx.

Kept at 165 ° C.

Then it is dissolved with 330 parts of xylene and

72.2 parts of a monoisocyanate (made from

1 mol of isophorone diisocyanate and 1 mol of dimethylethanolamine, 50% in xylene) were added. After about 4 hours at

The addition of the monoisocyanate is complete at 60 ° C.

It is dissolved in 189 parts of butyl acetate.

The thus obtained copolymer solution 2 has a body Fest¬ of 64.9% (15 '180 C ^β), and a viscosity of 21 dpa.s (original) or 0.8 dPas.s (50% in butyl acetate), each determined at 23 ° C. The residual content of free vinyl ester monomers in the 65% solution was determined by gas chromatography to be 0.5-1.0% by weight. This corresponds to a residual monomer content of 3.8 to 7.6% by weight, based on the total amount of vinyl ester monomer used.

The original copolymer solution 2 obtained (64.9% solids at 15 "180 ° C.) is diluted to 62% solids with methoxypropylacetate (copolymer solution 2a). To 54.35 parts of a tinting paste based on a commercially available OH-acrylate (OH Number of 150 mg KOH / g) 45.65 parts of the copolymer solution 2a (62% solids) are added This master lacquer solution is mixed in a volume ratio of 2: 1 with the polyisocyanate solution 1. Based on 10% by weight solution to the Stammlacklö¬, the paint dilution 1 is a spray viscosity of 18 s, measured in a DIN 4 flow cup, einge¬ sets. from this varnish 1 glass lifts were Untitled angefer¬ and 30 min baked at 60 ^β C. the Abprüfergeb- nit shows Table 1.

Lacquer 1 was also coated on phosphated and with a commercially available 2-component polyurethane filler (OH components ■ polyester-modified hydroxyl-containing acrylate with an OH number of 140 - 150 mg KOH / g; isocyanate component "via the biuret structure trimerized hexamethylene diisocyanate) coated steel sheets applied and 30 min. baked at 60 ° C. The test results are shown in Table 2.

Comparative Example 1

Analogous to the procedure according to the English technical information "Veo Va poly ers

LR 40 and LR 2041 for water-thinnable paints "der

Shell was made with the monomer mixture

Example 1 prepared a copolymer solution 3 as follows:

In a 4-liter stainless steel kettle with stirrer, reflux condenser and inlet devices, 147 parts of solvent naphtha, 165 parts of 2-methoxypropyl acetate, 264 parts of a commercially available mixture of vinyl esters of saturated aliphatic monocarboxylic acids with predominantly 10 carbon atoms, which <? - C atoms are branched, 60 parts of styrene and 2.4 parts of di-tert. Submitted butyl peroxide and heated to 160 ° C.

Weigh and mix in the monomer tank:

540 parts of styrene

194.4 parts of hydroxyethyl methacrylate

108 parts of methyl methacrylate

Weigh and mix in the initiator tank:

21.6 parts tert. Butyl perbenzoate 64.8 parts solvent naphth ^ 2.4 parts dodecyl mercaptan

Monomer and initiator tanks are evenly metered in over 4.5 h, - the temperature is kept at 155-160 ° C. Then within 0.5 h 21.6 parts of hydroxyethyl methacrylate and 12 parts of methyl methacrylate

from the monomer tank and

10.8 parts of solvent naphtha I 3.6 parts of tert. Butyl perbenzoate

added from the initiator tank.

0.5 h after this replenishment will be repeated

25.2 parts of solvent naphth.! ^ 8.4 parts of tert. Butyl perbenzoate

metered in from the initiator tank within 0.5 h. After post-polymerization for 0.5 h, 253.8 parts of butyl acetate are dissolved.

The thus obtained copolymer solution 3 had a solids (1 h 130 ^β C) of 67.3% and a viscosity of 1.65 dPa.s (50% solution in ethyl glycol acetate at 23 ° C). The residual content of free vinyl ester monomers in the 67.3% polymer solution was determined by means of gas chromatography under the same conditions as in copolymer solution 1. A content of 5.1% by weight was found. This corresponds to a residual monomer content of 33% by weight, based on the total amount of vinyl ester used, taking into account the theoretical solids content of the polymer solution of 70%. Comparative Example 2

Analogous to the procedure according to the English-language technical information "Veo Va polymers

LR-40 and LR-2041 for water-thinnable paints "from Shell, a copolymer solution 4 was prepared as follows:

In a 4-liter stainless steel kettle with stirrer, reflux condenser and inlet devices are placed and heated to 150-155 ° C

400, - parts of a commercially available mixture of vinyl esters of unsaturated, aliphatic monocarboxylic acids with predominantly 10 carbon atoms, which are branched on the ^ -C atom.

120 parts styrene 421.4 parts Shellsol Ä ^

5.7 parts of di-tert. Butyl peroxide

Weigh and mix in the monomer feed

480 parts of styrene 252 parts of n-butyl acrylate 468 parts of hydroxyethyl methacrylate 144 parts of methyl methacrylate 36 parts of methacrylic acid Weigh and mix in the initiator tank:

351.2 parts Shellsoll A ^

22.8 parts of tert-butyl perbenzoate

The monomer and initiator tanks are metered in uniformly over the course of 4.5 hours, while the temperature is kept at 150-155 ° C. Then the monomer tank is removed within 0.5 h

28 parts of n-butyl acrylate 52 parts of hydroxyethyl methacrylate 16 parts of methyl methacrylate 4 parts of methacrylic acid and from the initiator tank

105.36 parts Shellso. ß

5.52 parts of tert-butyl perbenzoate

added. After 0.5 h, three portions of 4.8 parts of tert-butyl perbenzoate are added at intervals of 0.5 h. 41.9 parts of a monoisocyanate (adduct of 1 mol of isophorone diisocyanate and 1 mol of dimethylethanolamine, 50% strength in xylene) are added to 1,486.5 parts of the copolymer solution thus obtained and added to the copolymer at 60 ° C. in the course of 4 hours . It is further dissolved in 100.4 parts of butyl acetate and 76.5 parts of 1-methoxypropylacetate-2. The thus obtained copolymer solution 4 has a body Fest¬ of 63.8%, the viscosity is original> 40 dPa.s (at 23 ^β C). The free vinyl ester monomer content in the 64.8% solution was 1.5-2% by weight. This corresponds to a residual monomer content of 11.5 to 15.2% by weight, based on the total amount of vinyl ester used.

The copolymer solution 4 obtained is diluted to 62% solids with methoxy propyl acetate. 45.65 parts of the copolymer solution 4 (62% solids) are added to 54.35 parts of a tinting paste based on a commercially available OH acrylate (OH number 150 mg KOH / g). This stock lacquer solution is mixed with the polyisocyanate solution 1 analogously to Example 2 in a volume ratio of 2: 1. A spray viscosity of 18 s, measured in the DIN 4 discharge cup, is set at 22% by weight, based on the base paint, of paint thinner 1. Analogously to Example 2, 2 glass lifts were made with this lacquer and baked at 60 ° C. for 30 minutes. The test results are shown in Table 1. Furthermore, paint 2 was applied analogously to Example 2 on phosphated steel sheets coated with the filler described in Example 2 and baked at 60 ° C. for 30 minutes. The test results are shown in Table 2.

Table 1: Test results of the glass lifts

Lacquer 1 Lacquer 2 Lacquer 3 Lacquer 4 Comparison Comparison

Pendulum hardness after king (s) 157 134 151 141 Table 2: Test results of the coated steel sheets

The steel sheets were baked at room temperature for 1 h. stored and then subjected to the tests.

1 . M. : slight marking:

a: Permanent irrigation with deionized water

20 ° C b: Mask the sheets with scotch tape. After an adhesive time of 1 h, remove the tape and examine for any markings that may be present. c: Distinctness of Reflected Image:

If the surface to be assessed is illuminated below 30 ° C, the direct reflection is measured at a gloss angle of - 30 ° and in the immediate vicinity of the gloss angle at - 30 ° ± 0.3 °. The DOI value determined from this corresponds to the visually perceived sharpness of the mirror image of an object on this surface. The DOI value is also called the sharpness value.

Measured values: 100 - best value

0 - worst value

Meter lighting observation

DORIGON 30 ° - 30 °, - 29.7 °,

30.3 ° D 47 R-6F from Hunter-Lab

Example 3

The copolymer solution prepared in Example 2 2 (solids 64.9% (15 * 180 ^β C) is reacted with 1-methoxypropyl-2 pylacetat diluted to 62% solids and with the Components specified in Table 3 processed into a clear coat 3. The clear lacquer 3 obtained was mixed with the polyisocyanate solution 1 in a volume ratio of 2: 1. The resulting mixture had a viscosity of 16 s (measured in a DIN 4 cup at 23 ° C.). After 4 hours' storage at room temperature of the clear lacquer mixture, the viscosity had risen to 28 s (DIN 4 cup, 23 ° C.), and after 6 hours of storage at room temperature to 68 s (DIN 4 cup, 23 ° C.). Analog to Example 2, 3 glass lifts were made from this lacquer (dry layer thickness 20 .mu.m) and 30 min. baked at 60 ° C. The test results are shown in Table 1.

The clear lacquer mixture 3 was also applied directly after the preparation as a clear lacquer by the wet-on-wet method to a commercially available basecoat (metallic basecoat silver based on cellulose acetobutyrate, polyester, melamine resin, wax) and baked at 60 ° C. for 30 min . The basecoat, in turn, had previously been applied to phosphated steel sheets coated with the filler described in Example 2. The test results are shown in Table 2.

Comparative Example 3

The copolymer solution 4 prepared in comparative example 2 is diluted to 62% solids with 1-methoxypropylacetate-2 and processed into a clear lacquer 4 using the components shown in table 3, analogously to example 3. The clear coat 4 obtained was mixed with the polyisocyanate solution 1 in a volume ratio of 2: 1 and 10% by volume, based on the clear coat 4, of the paint thinner 1 was added. The resulting clearcoat mixture had a viscosity of 19 s (DIN 4 cup, 23 ° C). After 4 hours' storage at room temperature, the viscosity of the mixture had risen so much (beginning to gel) that the

Clear varnish 4 was no longer processable.

Analogously to Example 3, 4 glass elevators were made from this lacquer (dry layer thickness 20 μm) and baked at 60 ° C. for 30 minutes. The test results are shown in Table 1.

In addition, this lacquer 4 was applied directly after its production analogously to example 3 as a clear lacquer on the basecoat described in example 3 by the wet-on-wet method (layer structure analogous to example 3) and for 30 minutes. baked at 60 ^° C. The test results are shown in Table 2.

In addition, in contrast to Example 3, a shift in the color of the basecoat by the clearcoat 4 was observed.

Table 3: Compositions of clearcoats 3 and 4

Clear coat 3 clear coat 4

Copolymer solution 2 75.7 parts

Copolymer solution 4 - 75.7 parts

Xylene 1.2 parts 1.2 parts

Butyl acetate 14.1 parts 14.1 parts

Solventnaphtff ^ 0.9 parts 0.9 parts

Butyl glycol acetate 0.7 part 0.7 part

Silicone oil solution 3.7 parts 3.7 parts

Catalyst solution ³ 1.5 parts 1.5 parts

Light stabilizer 1.2 parts 1.2 parts (hindered amine)

UV absorber (benzotriazole) 1.0 part 1.0 part the catalyst solution consists of the solution of 1 part of dibutyltin dilaurate in 50 parts of butyl acetate, 44 parts of solvent naphtha * and 5 parts of 3-methoxybutyl acetate.

Claims

Claims:

1.) Hydroxyl group-containing copolymer (A) which can be prepared by means of free-radical solution polymerization and is based on vinyl esters, vinyl aromatics and hydroxyl alkyl esters. ^ - Unsaturated carboxylic acids and, if appropriate, further copolymerizable monomers, characterized in that the copolymer (A) has an OH number of 50 to 200 mg KOH / g, preferably 70 to 150 mg KOH / g and an average molecular weight (number average) of 1,500 to 6,000 and can be produced by radical solution dol _. polymerization at temperatures from 130 to 200 ° C., preferably 150 to 180 ° C., from

a) 5 to 25% by weight, preferably 10 to 19% by weight, of one or more vinyl esters of monocarboxylic acids, preferably vinyl esters of monocarboxylic acids having 5 to 15 carbon atoms, branched in the (. position) per molecule,

a,) 10 to 50 wt .-%, preferably 20 to 45

% By weight of one or more vinyl aromatic hydrocarbons, a_) 10 to 40% by weight, preferably 15 to 35

% By weight of one or more hydroxy alkyl ^ unsaturated carboxylic acids,

a.) 0 to 40% by weight of other ethylenically unsaturated, copolymerizable monomers, the sum of components a. to a. each gives 100% by weight, whereby

1.) at least 60% by weight, preferably 100

Wt .-%, of the total amount of component a to be presented, ^■ * ^■

2.) the components a, to a, and the rest of component a, if any, are metered in within a monomer addition period of the same length for all components in such a way that

ii) the amount of components a_ and a added per unit of time. remains constant within the monomer addition period and iii) the amount of component a_ added in the first third of the monomer addition period 15 to 30% by weight, preferably 18 to 26% by weight, the total amount of component a_, in the second third 25 to 40% by weight. %, preferably 30 to 38% by weight and within the last third 35 to 60% by weight, preferably 40 to 50% by weight, of the total amount of component a_.

2.) Process for the preparation of copolymers (A) containing hydroxyl groups based on vinyl esters, vinyl aromatics, hydroxyalkyl esters ₄ , β-unsaturated carboxylic acids and, if appropriate, further copolymerizable monomers by means of radial solution polymerization, characterized in that

a.) 5 to 25% by weight, preferably 10 to 19

% By weight of one or more vinyl esters of monocarboxylic acids, preferably vinyl esters of monocarboxylic acids having 5 to 15 carbon atoms per molecule and branched in the ^ position,

a ₂ ) 10 to 50% by weight, preferably 20 to 45

% By weight of one or more vinyl aromatic hydrocarbons, a ₃ ) 10 to 40% by weight, preferably 15 to 35

% By weight of one or more hydroxyalkyl esters Carboxylic acids,

a.) 0 to 40% by weight of other ethylenically unsaturated, copolymerizable monomers, the sum of components a. to a. each gives 100% by weight,

at temperatures of 130 to 200 ^β C, preferably 150 to 180 ° C, to give a copolymer (A) having an OH number of 50 to 200 mg KOH / g, bevor¬ Trains t 70 to 150 mg KOH / g and an average molecular weight (Number average) from 1500 to 6000 are implemented, whereby

1.) at least 60% by weight, preferably 100

% By weight of the total amount of component a. be presented

2.) the components a_ to a. and the rest of component a, if any, are metered in within a monomer addition period of the same length for all components in such a way that

i) the amount of component a added per unit of time. remains constant or decreases within the monomer addition period.,

ii) the amount of components a_ and a added per unit of time. remains constant within the monomer addition period and

iii) the amount of component a- 15 to 30% by weight, preferably 18 to 26% by weight, of the total amount of component a_ added within the first third of the monomer addition period, within the second

Thirds 25 to 40% by weight, preferably 30 to 38% by weight and within the last third 35 to 60% by weight, preferably 40 to 50% by weight, of the total amount of component a_.

3.) Hydroxyl group-containing copolymer (A) according to claim 1 or method according to claim 2, characterized in that the copolymer (A) has an amine number of 1 to 10 mg KOH / g, preferably 1 to 5 mg KOH / g and / or has an acid number of 5 to 30 mg KOH / g, preferably 8 to 25 mg KOH / g.

4.) Hydroxyl group-containing copolymer (A) or process according to claim 3, characterized gekennzeich¬ net that the amino groups by reaction with compounds which per molecule on average 0.8 to 1.5, preferably 1, free isocyanate group and at least 1 tertiary Contain amino group into which hydroxyl-containing copolymer (A) have been introduced.

5.) Hydroxyl group-containing copolymer (A) according to claim 1, 3 or 4, or process according to claim 2 to 4, characterized in that as component a, one or more vinyl esters of saturated aliphatic monocarboxylic acids with 9-11 C atoms, which are branched amet carbon atom can be used.

6.) Coating agent, characterized in that it is the hydroxyl-containing copolymer

(A) according to claim 1 or 3 to 5 as binders.

7.) Coating composition according to claim 6, characterized in that it contains polyisocyanates as hardeners.

8.) Use of the hydroxyl-containing copolymers (A) according to claim 1 or 3 to 5 as binders in coating compositions for automotive refinishing.

9.) Use of the hydroxyl-containing copolymers (A) according to claim 1 or 3 to 5 as binders in clearcoats or pigmented topcoats.

0168Z