EP0364450A1

EP0364450A1 - Hardenable composition based on branched acrylates with carboxyl groups and/or branched acrylates with epoxy groups and aminoplastic resins

Info

Publication number: EP0364450A1
Application number: EP88902840A
Authority: EP
Inventors: Werner Alfons Jung
Original assignee: BASF Lacke und Farben AG
Current assignee: BASF Farben und Fasern AG
Priority date: 1987-03-31
Filing date: 1988-03-25
Publication date: 1990-04-25
Also published as: BR8807440A; EP0285034A1; CA1323119C; EP0285034B1; ZA882271B; DE3710668A1; JPH0689116B2; KR890700641A; DE3866394D1; KR920001047B1; AU612361B2; AU1545888A; ATE69828T1; WO1988007565A1; ES2028158T3; JPH02500281A; US5331052A

Abstract

A hardenable composition comprises: A) a polymer with at least 2 COOH groups, B) a polymer with at least 2 epoxy groups, C) an aminoplastic resin. At least one of the components A) or B) is based on a branched soluble acrylate copolymer for the manufacture of which more than 3 to 30 wt.%, with respect to the total weight of the monomers, of a monomer with at least two polymerizable olefinically unsaturated double bonds is used and the ratios of the quantities of the individual components are chosen so that the molar ratio of the carbonyl groups of component A) to the epoxy groups of component B) is between 3:1 and 1:3 and that the ratio of the weight of the epoxy resin components to the weight of the aminoplastic resin components is between 65:35 wt.% and 98:2 wt.%. The invention also relates to coating materials based on the hardenable composition.

Description

Curable composition based on branched acrylates with carboxyl groups and / or branched acrylates with epoxy groups and aminoplast resins

The invention relates to a curable composition based on branched, soluble acrylate copolymers which are obtainable by copolymerizing monomers with at least two polymerizable, olefinically unsaturated double bonds, functional group-bearing monomers and further polymerizable monomers with an olefinically unsaturated double bond.

From the generic EP-A 103 199 an acrylate copolymer is known which has been obtained by copolymerization of 10 to 95% by weight of t-butyl acrylate, 0.1 to 3% by weight of polyfunctional monomers, such as trimethylolpropane triacrylate, 1 to 30 % By weight of comonomers with a functional group and 0 to 80% by weight of further, polymerizable, ethylenically unsaturated monomers. Comonomers with a functional group include monomers containing carboxyl groups, such as acrylic acid and methacrylic acid. From this document a coating composition is also known which contains a carboxyl-containing acrylate copolymer branched by polymerizing polyethylenically unsaturated monomers and a polyepoxide as crosslinking agent. The branched acrylate copolymers described lead to coatings with good weather resistance, in particular good moisture resistance, which can be attributed to the content of polymerized t-butyl acrylate. From DE-PS 30 22 996 a stoving lacquer is known in which carboxyl-containing polymers such as acrylates based on acrylic acid or methacrylic acid and glycidyl-containing acrylates can be mixed to form a curable composition. This leads to films with higher hardness and

Weather resistance.

WO 84/00771 describes a multi-component system in which a total of four types of binder or components are mixed with one another and then applied; the components are: a) OH-acrylate, b) acid anhydride, at least 50% being alkylhexahydrophthalic anhydrides, c) epoxy resin and d) melamine resin.

No information is given on the pot life of the mixture; A particular advantage over conventional systems is the high solids in the application, sometimes larger than 70% solids.

DE-OS 23 33 384 describes a binder based on acrylated polyester, i.e. in an OH polyester (or alkyd resin), an OH acrylate is polymerized with a relatively low acid number, and crosslinking can be carried out with melamine resins and epoxy resins at the same time. The proportions are: 60 to 70% OH copolymer, 20 to 30% melamine resin, 5 to 15% epoxy resin.

Advantages over existing systems are said to be: improved weather resistance (hence aromatics low in aromatics), improved solvent resistance and improved tendency of the paints to run off on vertical surfaces. The object of the present invention was to combine all the positive properties of the known coating compositions in a curable composition, in particular to improve the properties of the coating compositions with regard to their resistance to long-term exposure to solvents, chemicals, water or water vapor, and at the same time good hardness and to achieve elasticity. Furthermore, it should be possible to achieve a high solids content of the curable coating compositions with a relatively low viscosity for economic reasons.

This object is surprisingly achieved by a curable composition which consists of carboxyl group-containing polymers, epoxy group-containing polymers and aminoplast resins and the epoxy component and / or the carboxyl component is based on a soluble, branched acrylate copolymer which has a higher proportion of copolymerized, polyethylenically unsaturated monomers has than the acrylate resins described in EP-A-103 199. In comparison with linear acrylate resins and the acrylate resins from EP-A-103 199, a lower viscosity with a relatively high solids content can be achieved with the acrylate copolymers according to the invention. Only through the reaction conditions according to the invention during the copolymerization can proportions of substantially more than 3% by weight of polyunsaturated monomers be incorporated into the acrylate resin. The highly branched structure of the copolymer makes the functional groups of the acrylic resin more reactive, which has a great advantage.

The present invention relates to a curable composition consisting of

A) a polymer with at least two carboxyl groups,

B) a polymer with at least two epoxy groups and C) an amine plastic resin, which is characterized in that at least one of components A) or B) is based on a branched, soluble acrylate copolymer,

wherein in the production of these branched acrylate copolymers more than 3 to 30 wt .-%, based on the total weight of the monomers, of a monomer with at least two polymerizable, olefinically unsaturated double bonds is used and the proportions of the individual components are chosen so that between the carboxyl groups of component A) and the epoxy groups of component B) have a molar ratio of 3: 1 to 1: 3 and that between the epoxy resin component B) and the aminoplast resin component C) a weight ratio of 65:35% by weight to 98: 2% by weight prevails.

Component A) is preferably essentially based on a soluble branched copolymer which is obtainable from

al) more than 3 to 30% by weight, preferably 5 to 25% by weight, of a monomer with at least two polymerizable, olefinically unsaturated double bonds,

a2) 3 to 50% by weight, preferably 8 to 40% by weight, of a monomer containing carboxyl groups and

a3) 40 to 93% by weight of further monomers with a polymerizable, olefinically unsaturated double bond,

the sum of a1), a2) and a3) being 100% by weight.

Compounds of the general formula can advantageously be used as component a1) are used in which mean:

R = H or CH ₃

X = O, NR ', S with R' = H, alkyl, aryl n = 2 to 8.

Examples of such compounds are hexanediol diacrylate, hexanediol dimethacrylate, glycol diacrylate, glycol dimethacrylate, butanediol diacrylate, butanediol dimethacrylate, hexamethylene bis methacrylamide, trimethylol propane triacrylate, trimethylol propane trimethacrylate and similar compounds. Divinyl compounds such as divinylbenzene are also suitable. Polyunsaturated monomers with a functional group can also be used, for example bisacrylamidoacetic acid. Combinations of the polyunsaturated monomers can of course also be used.

Other possible components a1) are reaction products of a carboxylic acid with a polymerizable, olefinically unsaturated double bond and glydidyl acrylate and / or glycidyl methacrylate. A polycarboxylic acid or unsaturated monocarboxylic acid esterified with an unsaturated alcohol containing a polymerizable double bond can also be used as component a1). Reaction products of a polyisocyanate with unsaturated alcohols or amines containing polymerizable double bonds are also used as monomers with at least two polymerizable, olefinically unsaturated double bonds. An example of this is the reaction product from one mole of hexamethylene diisocyanate with two moles of allyl alcohol. Β-Carboxyethyl acrylate is particularly suitable as component a2); acrylic acid, methacrylic acid, itaconic acid, crotonic acid, aconitic acid, maleic and fumaric acid or their half-esters are also suitable.

The selection of component a3) depends largely on the desired properties of the acrylate copolymer in terms of elasticity, hardness, compatibility and polarity. These properties can be partly determined using the known glass transition temperatures of

Control monomers. The monomers can be selected from the group of styrene, vinyl toluene, alkyl esters of acrylic acid and methacrylic acid, alkoxyethyl acrylates and aryloxyethyl acrylates and the corresponding methacrylates, and esters of maleic and fumaric acid.

In addition, monomers containing hydroxyl groups can be used as component a3), for example hydroxyalkyl esters of acrylic and / or methacrylic acid. It is possible, as further monomers with a polymerizable olefinically unsaturated double bond 0.1 to 5% by weight, based on the total weight of all monomers, of monomers with phosphoric acid groups, e.g. Use phosphoric acid esters with polymerizable double bonds.

It is particularly advantageous if monomers are incorporated in the acrylate copolymer having an acid number of 20 to 250, preferably 50 to 180, which contain groups which catalyze subsequent crosslinking of the carboxyl group-containing acrylate copolymer with epoxy groups, for example tertiary amino groups.

The present invention also relates to a curable composition which is characterized in that essentially a soluble branched acrylate copolymer which is obtainable from is used as component A) a1) more than 3 to 30% by weight, preferably 5 to 25% by weight, of a monomer with at least two polymerizable, olefinically unsaturated double bonds, di- and polyesters being excluded from di- and polyols with acrylic acid,

a2) 3 to 50% by weight, preferably 8 to 40% by weight, of a monomer containing corboxyl groups,

a3) 0.1 to 20% by weight, preferably 1 to 10% by weight, of a tertiary amine with a polymerizable, olefinically unsaturated double bond,

a4) 0 to 40% by weight, preferably 5 to 25% by weight, of a hydroxyl-containing monomer and

a5) 0 to 80% by weight of further monomers with a polymerizable, olefinically unsaturated double bond, the sum of components a1), a2), a3), a4) and a5) being 100% by weight.

Compounds of the general formula can advantageously be used as component a1)

in which mean:

X = 0, NR ', S with R = H, alkyl, aryl n = 2 to 8

be used.

Component a1) can be a reaction product of a carboxylic acid with a polymerizable, olefinically unsaturated double bond, acrylic acid being excluded and be glycidyl methacrylate. Furthermore, polycarboxylic acids or unsaturated monocarboxylic acids esterified with an unsaturated alcohol containing a polymerizable double bond, with the exception of derivatives of acrylic acid, are suitable

Components a1) selected from products that are produced from polyisoeyanates with unsaturated, polymerizable double bonds containing alcohols or amines.

Examples of ethylenically unsaturated compounds having a tertiary amino group, ie for component a3), are N, N'-dimethylaminoethyl methacrylate, N, N'-diethylaminoethyl methacrylate, 2-vinylpyrldine and 4-vinylpyridine, vinylpyrroline, vinylquinoline, vinylisoquinoline, N, N ' -Dimethylaminoethyl vinyl ether and 2-methyl-4-vinyl pyridine.

Optionally, monomers containing hydroxyl groups can be used. Examples include his hydroxyalkyl ester of acrylic and methacrylic acid, e.g. Hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate,

Hydroxyamyl acrylate, hydroxyhexyl acrylate, hydroxyoctyl acrylate and the corresponding methacrylates. The further monomers with a polymerizable, olefinically unsaturated double bond are selected from the group already mentioned above.

In this case too, it may be advantageous to use 0.1 to 5% by weight, based on the total weight of all monomers, of monomers with phosphoric acid groups as further monomers with a polymerizable double bond.

It is particularly preferred if essentially a soluble branched acrylate copolymer which is obtainable from is used as component A)

a1) more than 3 to 30% by weight, preferably 5 to 25% by weight, of a monomer with at least two polymerizable, olefinically unsaturated double bonds, whereby di- and polyesters are excluded from di- and polyols with acrylic acid,

a2) 0.1 to 20% by weight, preferably 1 to 10% by weight, of a tertiary amine with a polymerizable, olefinically unsaturated double bond,

a3) 5 to 40% by weight, preferably 10 to 30% by weight, of monomers containing hydroxyl groups,

a4) 0 to 80% by weight of further polymerizable monomers with an olefinically unsaturated double bond and from

a5) cyclic carboxylic anhydrides,

the sum of a1) to a4) being 100% by weight.

Compounds of the general formula can advantageously be used as component a1

in which mean:

X = 0, NR, S with R = H, alkyl, aryl n = 2 to 8

be used.

Examples of polyethylenically unsaturated compounds are hexanediol dimethacrylate, glycol dimethacrylate, butanediol dimethacrylate, trimethylolpropane trimethacrylate, divinylbenzene and similar compounds. The ethylenically unsaturated compounds already mentioned can advantageously also be used, provided that that it is not di- and polyester of di- and polyols with acrylic acid.

The polymerisable tertiary amines are those which have already been mentioned.

Suitable as component a3) are hydroxyalkyl esters of acrylic and / or methacrylic acid with a primary hydroxyl group, e.g. Hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyamyl acrylate, hydroxyhexyl acrylate, hydroxyoctyl acrylate and the corresponding methacrylates and also hydroxyalkyl esters with a secondary OH group, such as 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate and 3-hydroxybutyl acrylate.

Also suitable as component a3) are reaction products of acrylic acid and / or methacrylic acid with the glycidyl ester of a carboxylic acid with a tertiary α-carbon atom.

The selection of component a4) is not particularly critical and depends on the desired properties of the acrylate copolymer. It should be mentioned that carboxyl group-containing monomers can also be used as component a4).

Examples of component a5) are phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic anhydride and their halogenated derivatives.

The invention also relates to a curable composition which is characterized in that essentially a soluble, branched acrylate copolymer which is obtainable from is used as component A)

al) more than 3 to 30% by weight, preferably 5 to 25% by weight,

Monomers with at least two polymerizable, olefinically unsaturated double bonds, a2) 1 to 30 wt .-%, preferably 3 to 20 wt .-%, monomers with cyclic carboxylic acid anhydride groups, and

a3) 45 to 80% by weight of further polymerizable monomers with an olefinically unsaturated double bond,

the sum of a1) to a3) being 100% by weight, and from

a4) compounds which contain both at least one hydrogen which is reactive with acid anhydride groups and at least one tertiary amino group,

some of the carboxylic acid anhydride groups can also be reacted with a monofunctional compound with active hydrogen.

Suitable as component a1) are the polyethylenically unsaturated monomers already mentioned, including the di- and polyesters of di- and polyols with acrylic acid.

Examples of monomers with cyclic carboxylic acid anhydride groups are maleic anhydride or itaconic anhydride.

The selection of component a3) depends on the desired properties of the acrylate copolymer. It should be mentioned that monomers with carboxyl groups, for example acrylic acid or methacrylic acid, are also suitable in the present case.

As component a4) it is advantageous to use alcohols which contain a tertiary amino group and primary or secondary amines with a tertiary amino group. The reactive hydrogen of component a4) can originate from a hydroxyl group, a primary or secondary amino group or a thiol group. Examples of alcohols with tertiary amino groups are

Adducts of secondary amines and epoxy compounds. Examples of secondary amines are dimethylamine, diethylamine, dipropylamine, dibutylamine, morpholine and pyrrolidine.

Examples of suitable epoxy compounds are ethylene oxide, propylene oxide, butylene oxide, styrene oxide and cyclohexene oxide.

Suitable alcohols with tertiary amino groups, which are obtained by reaction of secondary amines with epoxy compounds, are dimethylaminoethanol, diethylaminoethanol, di-n-propylaminoethanol, dilsσpropylaminoethanol, di-n-butylaminoethanol, N- (2-hydroxyethyl) morpholine, N- (2- hydroxyethyl) piperidine, N- (2-hydroxyethyl) pyrrolidone, N- (2-hydroxyethyl) azeridine, N, N'-dirnethyl-2-hydroxypropylamine, N, N'-diethyl-2-hydroxypropylamine, triethanaolamine and tripropanolamine.

Examples of the primary or secondary amines containing a tertiary amino group are N, N'-dialkyl-1,3-propylenediamines, e.g. N, N'-dimethyl-1,3-propylenediamine, N, N'-diethyl-1,3-propylenediamine and N, N'-dialkyl-1,4-tetraethylenediamines, e.g. N, N'-dimethyl-1,4-tetramethylene diamine and N, N'-diethyl-1,4-tetramethylene diamine. N, N'-Dialkyl-1,6-hexamethylenediamines and N-alkylpiperazines as well as 2-aminopyridine, 4-aminopyridine and N-alkylaminopyridine are also suitable.

It should be noted that some of the carboxylic anhydride groups can also be reacted with a monofunctional compound with active hydrogen, e.g. Alcohols, can be implemented.

Component A) is advantageously obtained from

a1) more than 3 to 30% by weight, preferably 5 to 25% by weight,

Monomers with at least two polymerizable, olefinically unsaturated double bonds, a2) 1 to 30% by weight of glycidyl esters of ethylenically unsaturated carboxylic acids and / or glycidyl ethers of olefinically unsaturated compounds,

a3) 40 to 95% by weight of further polymerizable monomers with an olefinically unsaturated double bond,

the sum of all monomers being 100% by weight, and from

a4) amines with a secondary amino group or di- or polyamines with at least one tertiary amino group and a primary or secondary amino group and / or

a5) Carboxylic acids containing a tertiary nitrogen atom and from

a6) cyclic carboxylic anhydrides.

Component a1) includes the polyethylenically unsaturated monomers already mentioned.

Examples of component a2) are glycidyl esters of acrylic acid or methacrylic acid and allyl and vinyl glycidyl ethers, glycidyl vinyl esters or glycidyl allyl esters, such as glycidyl vinyl phthalate, glycidyl allyl phthalate.

The selection of component a3) depends on the desired properties of the acrylate copolymer and can be made from the group already mentioned above. However, monomers containing carboxyl groups and amino groups should not be used as component a3), since these react with the oxirane group of component a2). The proportion of monomers containing hydroxyl groups should be as low as possible. If hydroxyl groups are necessary to achieve a certain polarity of the copolymer, monomers with secondary OH groups should be preferred. Examples of component a4) are imidazoi, aminopyridine, N-alkylaminopyrldine, ethylpiperazine, dibutylamine.

Examples of component a5) are 3- and 4-dimethylaminobenzoic acid, picolinic acid and dimethylaminosalicylic acid.

Examples of component a6) are phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic anhydride and their halogenated derivatives.

Component A) can be a soluble branched acrylate copolymer which is obtainable from

a1) more than 3 to 30% by weight, preferably 5 to 25% by weight, of a monomer with at least two polymerizable, olefinically unsaturated double bonds,

a2) 3 to 50% by weight, preferably 8 to 40% by weight, of a monomer containing carboxyl groups,

a3) 0 to 40% by weight, preferably 3 to 25% by weight, of a monomer containing hydroxyl groups and

a4) 0 to 80% by weight of further monomers with a polymerizable, olefinically unsaturated double bond,

a5) monoisocyanates with a tertiary amino group in the molecule,

the sum of a1) to a4) being 100% by weight.

Addition products of diisocyanates with amino alcohols, such as, for example, dimethyl and DIethylaminoethanol, are suitable as component a5). The tertiary amino group can also be introduced, for example, by 2-hydroxyethylpyridine. An addition product of isophorone is particularly preferred diisocyanate with amino alcohols as component a5).

Component A) can also be obtained from

a1) more than 3 to 30% by weight, preferably 5 to 25% by weight, of a monomer with at least 2 polymerizable, olefinically unsaturated double bonds,

a2) 0 to 40% by weight, preferably 5 to 30% by weight, of a monomer containing carboxyl groups,

a3) 8 to 50% by weight, preferably 10 to 40% by weight, of monomers containing hydroxyl groups,

a5) Monoisocyanates with a tertiary amino group in the molecule and out

a6) cyclic carboxylic acid anhydrides,

the sum of a1) to a4) being 100% by weight.

In the event that component B) is essentially based on a soluble, branched acrylate copolymer, this is obtained from

b1) more than 3 to 30% by weight, preferably 5 to 25% by weight,

Monomers with at least two polymerizable, olefinically unsaturated double bonds,

b2) 5 to 50 wt .-%, preferably 10 to 40 wt .-%, monomers with an epoxy group and

b3) 10 to 91% by weight of further monomers with a polymerizable, olefinically unsaturated double bond, the sum of b1) to b3) being 100% by weight.

Glycidyl esters of unsaturated carboxylic acids or glycidyl ethers of unsaturated compounds are preferably used as component b2). Examples include: glycidyl acrylate, glycidyl methacrylate, glycidyl ester of maleic and fumaric acid, glycidyl vinyl phthalate, glycidyl allyl phthalate, glycidyl allyl malonate.

Component B) can be produced from

b1) more than 3 to 30% by weight, preferably 5 to 25% by weight,

b2) 5 to 50% by weight, preferably 10 to 40% by weight, of monomers with at least one polymerizable double bond and a functional group F,

b3) further polymerizable monomers,

b4) an organic compound with at least one epoxy group and a group reactive to the functional group F of the monomers from b2),

the sum of b1) to b3) being 100% by weight

As components b2) and b4) come monomers with an isocyanate group, such as isocyanatoethyl methacrylate and isocyanatobutyl methacrylate, and also epoxypropanol or else carboxylic acid monomers and di- or polyepoxide compounds.

Β-Carboxyethyl acrylate is preferably used as the proportion of monomers containing carboxyl groups. The carboxyl group-containing monomer is advantageously a monomer with phosphoric acid groups. The pre-crosslinked soluble acrylate copolymers A) and B) are prepared by the monomers in an organic solvent at 70 to 130 ° C, preferably at 80 to 120 ° C, using at least 0.5 wt .-%, preferably at least 2.5. % By weight, based on the total weight of the monomers, of a polymerization regulator and using polymerization initiators to be copolymerized to give a pre-crosslinked, branched but not gelled product. If necessary, after the radical copolymerization, the reaction with the cyclic carboxylic anhydrides, the reaction with the compounds which contain both at least one hydrogen which is reactive with acid anhydride groups and at least one tertiary amino group and, if appropriate, with monofunctional compounds with active hydrogen, or else the reaction with the secondary amines or the di- or polyamines with at least one tertiary amino group and a primary or secondary amino group and / or with carboxylic acids which contain a tertiary nitrogen, and with the cyclic carboxylic anhydrides or optionally with the monoisocyanates which contain a tertiary nitrogen group in the molecule , or after the copolymerization with the monoisocyanates, which contain a tertiary nitrogen group in the molecule and the reaction with cyclic carboxylic acid anhydrides, or the reaction of a compound with at least one epoxy group and a group reactive to the functional group F of the monomer b2).

When producing the acrylate copolymer, care must be taken that a pre-crosslinked but not gelled

Copolymer is obtained. Suitable polymerization conditions can surprisingly produce a clear, transparent, non-gelled solution of a branched copolymer. The use of monomers with at least two ethylenically unsaturated groups results in a pre-crosslinking of the copolymer molecules which, owing to the special react according to the invention conditions do not lead to gelled products.

The polymerization is carried out in such a way that a solution of the polymer with a solids content of 40 to 55% by weight results. The solids content depends on the proportion of polymerized, polyethylenically unsaturated monomers. If this proportion is low, polymerization can be carried out at higher solids contents.

It is also necessary to use suitable initiators and, depending on the proportion of difunctional monomer, at least 0.5% by weight, but preferably at least 2.5% by weight, of a polymerization regulator. The choice of initiator depends on the proportion of difunctional monomers used. If the proportion is low, the initiators customary for such temperatures, e.g. Peroxyester, use. With a higher proportion of difunctional monomer, initiators such as e.g. Azo compounds used. After the polymerization, the polymer solution is concentrated to the desired solids content by distilling off solvent, preferably to solids contents of 60% by weight. The clear copolymer solutions obtained in this way, when adjusted to a solids content of 50% by weight, have a viscosity of 0.4 to 10 dPas.

the polymerization is carried out in the presence of an organic solvent. Examples are ethanol, isopropanol, n-propanoal, n-B-utanol, isobutanol, t-butanol, methyl, ethyl, propyl and butyl esters of acetic acid, acetone, methyl ethyl ketone, xylene, toluene.

Compounds containing mercapto groups are preferably suitable as polymerization regulators, mercaptoethanol being particularly preferably used. Other possible regulators are, for example, t-dodecyl mercaptan, phenyl mercaptan, Octyldecyl mercaptan, butyl mercaptan and thiocarboxylic acids such as thiolactic acid.

It should be noted that no hydroxyl mercaptans or mercaptans with primary SH groups are used as polymerization regulators in the preparation of the acrylate copolymer according to claim 5. When selecting the polymerization regulator in the production of the acrylates according to claims 6, 9 and possibly 10, care must be taken that no thiocarboxylic acids are used.

Component C) (aminoplast resin) is melamine-formaldehyde resin, urea-formaldehyde resin and benzoguanamine resin. These can be fully or partially methylolated, but can also contain free NH groups. Partially and fully etherified resins can be used as component C). The use of mixed etherified products is often an advantage. Methanol, ethanol, propanol, isobutanol, n-butanol, ethylhexanol and others are suitable as etherification alcohol.

The present invention also relates to a process for the preparation of the curable compositions described above, characterized in that the polymer with at least two epoxy groups B) and the aminoplast resin C) are mixed together in organic solvent and this mixture is processed with the COOH polymer A ) is mixed.

The invention also relates to coating compositions which are characterized in that they contain the previously described curable compositions, optionally catalysts, organic solvents, optionally pigments and customary auxiliaries and additives.

If the catalyst for the epoxy-carboxy crosslinking is incorporated into the polymer, the amount depends on the desired baking temperature. At higher temperatures less tertiary amine is incorporated, more tertiary amine is incorporated at a low baking temperature.

It should be noted that when using the coatings for clear lacquers, mainly aliphatic amines are incorporated, since aromatic amines often lead to discoloration. Of course, catalysts can also be used externally. Suitable catalysts are metal salts, e.g. Chromium compounds, aluminum and titanium compounds.

The baking temperatures of the curable compositions described are generally from 80 to 180 ° C. The proportion of built-in catalysts advantageously allows the coating agents to be set to the desired stoving temperature.

The curable compositions described lead to coatings which have excellent properties with regard to resistance to long-term exposure to solvents, chemicals, water or water vapor, hardness and elasticity.

In addition, a relatively high solids content of the curable coating compositions is achieved with a relatively low viscosity.

The coating compositions based on the curable composition described can be used as fillers, topcoats and as the base and / or clearcoat of a metallic multilayer coating.

The invention is explained in more detail below on the basis of exemplary embodiments:

The viscosity values were determined on a plate-cone viscometer at 23 ° C, the solids values were determined in a forced air oven, unless otherwise stated, at 1 hour / 130 ° C. The acid numbers are given in mg KOH / g resin and relate to the solid resin. The epoxy equivalent weights also refer to solid resin.

Preparation of copolymer solutions according to the invention.

Production of a branched COOH acrylate, A1: are placed in a 4 liter stainless steel kettle

375.8 parts xylene

375.8 parts butanol

188.4 parts of methyl isobutyl ketone

Weigh and mix in the monomer tank

100 parts methyl methacrylate 100 parts n-butyl acrylate 170 parts tert-butyl acrylate 100 parts ethyl hexyl acrylate 100 parts styrene

200 parts hexanediol dimethacrylate 200 parts acrylic acid

30 parts of dimethylaminoethyl methacrylate

50 parts of mercaptoethanol

Weigh and mix in the initiator tank:

36.0 parts of 2,2'-azobis (2-methylbutanenitrile) 57.6 parts of xylene 57.6 parts of butanol 28.8 parts of methyl isobutyl ketone

The initial charge is heated to 110 ° C. and the monomer tank is metered in uniformly within 3 hours, and the initiator tank is metered in uniformly within 3.5 hours. Both inlets are started at the same time. During the polymerization, the temperature is kept at 110 ° C, after the end of the addition polymerization is continued for 2.5 hours. The clear solution of the branched acrylate thus obtained has a viscosity of 2.2 dPas (23 ° C), a solids content of 49.6% and an acid number of 132.6. Preparation of an Acrylate B1 Containing Glycidyl Groups:

In a 4 liter stainless steel kettle are placed and heated to 110 ° C:

282.9 parts xylene

565.8 parts of 1-methoxypropyl-2-acetate

Inlet 1:

270 parts of glycidyl methacrylate

Inlet 2:

135 parts of methyl methacrylate

90 parts styrene 180 parts n-butyl acrylate 135 parts hexanediol diacrylate

45 parts of ethyl hexyl acrylate

45 parts of hydroxypropyl methacrylate

40.5 parts mercaptoethanol

Inlet 3:

40.8 parts xylene

81.6 parts of 1-methoxypropyl-2-acetate

30.6 parts of 2,2'-azobis (2-methylbutanenitrile)

Inlets 1, 2 and 3 are started simultaneously; Feed 1 is metered in for 2.5 hours, feed 2 is metered in for 3 hours, feed 3 is metered in for 3.5 hours. The temperature is kept at 110 ° C. during the polymerization, after which polymerization is continued at 110 ° C. for 3 hours. Then 330 parts of solvent mixture are distilled off. The clear solution of the glycidyl group-containing acrylate resin thus obtained has a solids content of 58.8%, a viscosity of 8.0 dPas and an epoxy equivalent weight of 561.

Production of the glycidyl group-containing acrylate B2:

In a 4 liter stainless steel kettle are placed and heated to 110 ° C:

282.9 parts xylene

565.8 parts of 1-methoxypropyl-2-acetate The individual feed tanks are weighed and mixed:

Inlet 1:

270 parts of glycidyl methacrylate

Inlet 2:

45 parts of hydroxypropyl methacrylate

Inlet 3:

135 parts of methyl methacrylate

90 parts styrene 180 parts n-butyl acrylate

135 parts of hexanediol diacrylate

45 parts of ethyl hexyl acrylate

40.5 parts mercaptoethanol

Feed 4: 40.8 parts of xylene

81.6 parts of 1-methoxypropyl-2-acetate

30.6 parts of 2,2'-azobis (2-methylbutanenitrile)

Inlets 1, 3 and 4 are started at the same time. Feed 1 is metered in for 2.5 hours, feed 3 is metered in for 3 hours, feed 4 is metered in for 3.5 hours. Feed 2 is started after the end of feed 1 and metered in for 0.5 hours. The temperature is kept at 110 ° C. during the polymerization, after which polymerization is continued for 3 hours. 326 parts of the solvent mixture are distilled off. The clear acrylic resin solution thus obtained has a solids content of 59.2%, a viscosity of 9.5 dPas and an epoxy equivalent weight of 553.

Clear coat 1:

91.7 parts of the resin solution B2 according to the invention are etherified with 13.8 parts of a methanol / butanol mixture

Melamine resin (Cymel 1130) mixed and then with 85.14

Parts of the acrylic resin solution A1 combined. Clear coat 2:

94.12 parts of the resin solution B1 are mixed with 14 parts of a butanol-partially etherified melamine resin (Cymel 1158), then 85.14 parts of the COOH-acrylate solution AI are added.

The varnishes are diluted with a little pentahol and applied onto glass plates with 100 μm wet film thickness. The films are baked at 120 ° C for 30 minutes.

Clear coat 1:

2 hours after oven:

Pendulum hardness 120.4 seconds, 5 minutes of premium gasoline OK

Clear coat 2:

2 hours after oven:

Pendulum hardness 187, 6 seconds, 5 minutes of premium gasoline f. i. O.

Claims

1. Curable composition consisting of:

A) polymer with at least two COOH groups,

B) polymer with at least two epoxy groups and

C) aminoplast resin,

characterized in that at least one of components A) or B) is based on a branched, soluble acrylate copolymer, in the production of these branched acrylate copolymers more than 3 to 30% by weight, based on the total weight of the monomers, of a monomer having at least two polymerizable, olefinically unsaturated double bonds are used and the quantitative ratios of the individual components to one another are chosen such that a molar ratio of 3: 1 to 1: 3 prevails between the carboxyl groups of component A) and the epoxy groups of component B) and that between the Epoxy resin component and the aminoplast resin component, a weight ratio of 65:35 wt .-% to 98: 2 wt .-%.

2. Curable composition according to claim 1, characterized in that essentially a soluble branched acrylate copolymer is used as component A), which is obtainable from

a2) 3 to 50% by weight, preferably 8 to 40% by weight, of a monomer containing carboxyl groups and a3) 40 to 93% by weight of further monomers with a polymerizable, olefinically unsaturated double bond,

the sum of a1), a2) and a3) being 100% by weight.

3. Curable composition according to claim 1, characterized in that essentially a soluble branched acrylate copolymer is used as component A), which is obtainable from

a1) more than 3 to 30% by weight, preferably 5 to 25% by weight, of a monomer with at least two polymerizable, olefinically unsaturated double bonds, di- and polyesters being excluded from di- and polyols with acrylic acid,

a5) 0 to 80% by weight of further monomers with a polymerizable, olefinically unsaturated double bond,

the sum of components a1), a2), a3), a4) and a5) being 100% by weight.

4. Curable composition according to claim 1, characterized in that essentially a soluble branched acrylate copolymer is used as component A), which is obtainable from a1) more than 3 to 30% by weight, preferably 5 to 25% by weight, of a monomer with at least two polymerizable, olefinically unsaturated double bonds, di- and polyesters being excluded from di- and polyols with acrylic acid,

a5) cyclic carboxylic anhydrides,

the sum of a1), a2), a3) and a4) being 100% by weight.

5. Curable composition according to claim 1, characterized in that essentially a soluble, branched acrylate copolymer is used as component A), which is obtainable from

a1) more than 3 to 30% by weight, preferably 5 to 25% by weight, of monomers with at least two polymerizable, olefinically unsaturated double bonds,

a2) 1 to 30% by weight, preferably 3 to 20% by weight, monomers with cyclic carboxylic anhydride groups,

the sum of a1), a2) and a3) being 100% by weight, and from a4) compounds which contain both at least one hydrogen which is reactive with acid anhydride groups and at least one tertiary amino group,

6. Curable composition according to claim 1, characterized in that essentially a soluble branched acrylate copolymer is used as component A), which is obtainable from

a2) 1 to 30% by weight of glycidyl esters of ethylenically unsaturated carboxylic acids and / or glycidyl ethers of olefinically unsaturated compounds,

the sum of all monomers being 100% by weight, and from

a5) Carboxylic acids containing a tertiary nitrogen atom and from

a6) Cyclic carboxylic acid anhydrides.

7. Curable composition according to claim 1, characterized in that essentially a soluble branched acrylate copolymer is used as component A), which is obtainable from

a5) Monoisocyanates with a tert. Amino group in the molecule,

the sum of a1), a2), a3) and a4) being 100% by weight.

8. Curable composition according to claim 1, characterized in that essentially a soluble, branched acrylate copolymer is used as component A), which is available

a3) 8 to 50% by weight, preferably 10 to 40% by weight, of monomers containing hydroxyl groups, a4) 0 to 80% by weight of further polymerizable monomers with an olefinically unsaturated double bond and from

a5) Monoisocyanates with a tert. Amino group in the molecule and out

a6) cyclic carboxylic acid anhydrides,

the sum of a1), a2), a3) and a4) being 100% by weight.

9. Curable composition according to claim 1, characterized in that essentially a soluble, branched acrylate copolymer is used as component B), which is obtainable from

b1) more than 3 to 30% by weight, preferably 5 to 25% by weight, of monomers with at least two polymerizable, olefinically unsaturated double bonds,

b2) 5 to 50% by weight, preferably 10 to 40% by weight, monomers with an epoxy group,

b3) 10 to 91% by weight of further monomers with a polymerizable, olefinically unsaturated double bond,

the sum of b1), b2) and b3) being 100% by weight.

10. Curable composition according to claim 1, characterized in that essentially a soluble, branched acrylate copolymer is used as component B), which is obtainable from

bl) more than 3 to 30% by weight, preferably 5 to 25% by weight, of monomers with at least two polymerizable, olefinically unsaturated double bonds, b2) 5 to 50% by weight, preferably 10 to 40% by weight, of monomers with at least one polymerizable double bond and a functional group F,

b3) further polymerizable monomers,

the sum of b1, b2) and b3) 100 wt. -% amounts.

11. The curable composition according to claim 2, 5, 6, 7,

8, 9 and 10, characterized in that component a1) or b1) of the general formula

corresponds in which mean:

R = H or CH ₃

X = O, NR ', S with R' = K, alkyl, aryl n = 2 to 8.

12. Curable composition according to claim 3 and 4, characterized in that component a1) of the formula

corresponds to in which mean:

X = 0, NR, S with R = H, alkyl, aryl n = 2 to 8 or is a divinyl compound such as divinylbenzene.

13. The curable composition according to claim 2, 5, 6, 7,

8, 9 and 10, characterized in that component a1) or b1) is a monomer with at least two polymerizable, olefinically unsaturated double bonds, this monomer being a reaction product of a carboxylic acid with a polymerizable double bond and glycidyl acrylate and / or glycidyl methacrylate, or wherein this monomer is a polycarboxylic acid or unsaturated monocarboxylic acid esterified with an unsaturated alcohol containing a polymerizable double bond or wherein this monomer is a reaction product of polyisocyanates with unsaturated alcohols or amines containing polymerizable double bonds.

14. A curable composition according to claim 2, 3, 7 or

8, characterized in that the monomer containing carboxyl groups is at least partially (a2) β-carboxyethyl acrylate.

15. A curable composition according to claim 2, 3, 7 or

8, characterized in that the carboxyl group-containing monomer is partially a monomer with phosphoric acid groups.

16. Curable composition according to claim 1 to 15, characterized in that the further polymerizable monomers with an olefinically unsaturated double bond are selected from the group styrene, vinyl toluene, alkyl esters of acrylic acid and methacrylic acid, alkoxyalkyl acrylates and aryloxyalkyl acrylates and the corresponding methacrylates, esters of maleic , Fumaric, crotonic and direthylacrylic acid.

17. A process for the preparation of the curable composition according to claim 1 to 16, characterized in that the polymer with at least two epoxy groups B) and the aminoplast resin C) are mixed together in organic solvent and this mixture before processing with the COOH polymer A) is mixed.

18. Coating agent, characterized in that it contains the curable composition according to Claims 1 to 16, optionally

Contains catalysts, organic solvents, possibly pigments and common auxiliaries and additives