DE2110054A1 - Coating agents - Google Patents

Description

The invention relates to binders for coating compositions for metals, which are composed of mixtures of an externally crosslinkable acrylic resin and a crosslinking acrylic resin. The coating agents are used at temperatures above 120 ° C Baked into highly elastic and at the same time hard, weather-resistant coatings on metals.

From the German Auslegeschrift 1.244.410 it is known that To produce crosslinkable polymers with the help of alkoxymethyl isocyanates by, among other things, polymerization products with a molecular weight over 600, which contain Zerewitinoff-active hydrogen atoms in the molecule, with alkoxymethyl isocyanates to react. In this way, inter alia, crosslinkable lacquer coating agents can be obtained will. It is true that the products according to the process of this document have coating agents compared to other known coating agents Significant advantages, however, films made from them are with regard to optimal weather resistance at the same time high elasticity and hardness are not yet satisfactory.

It is further from British patent specification 1.159α859 known to mix binders for paints from several components by containing at least one hydroxyl group-

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of the polyacrylate resin, at least one N-alkoxymethyl urethane and optionally at least one melamine-formaldehyde and / or urea-formaldehyde resin are used. From N-Alkoxymethylurethanen reaction products of polyols with C ^ are here - C ^ 2 "~ ^A lkoxymethylisocyanaten understood as polyols, low molecular weight polyols such as glycerol, as polyether, polyester and polyurethanes are described in the application..

These combinations have insufficient weather resistance, especially with metal effect finishes leaves a lot to be desired. Metal effect finishes are in particular in automobiles exposed to strong weather conditions.

The object of the present invention is therefore to provide binders for coating compositions for metals, in particular for metal strip coatings (coil coating) and to produce metallic effect paints, the cured films of which have good weather resistance have a good surface hardness with high elasticity at the same time.

The object is achieved in that mixtures of an externally crosslinkable acrylic resin are used as binders in the coating compositions and a crosslinking acrylic resin can be used. A co-use elasticizing or cross-linking acting components, for example from the substance class of polyalcohols, polyethers, polyesters, polyurethanes, polyacetals, Urea, phenol or melamine-formaldehyde resins are no longer required.

The invention thus relates to binders for overlay masses for metals, consisting of a mixture of 10-90 parts by weight of an externally crosslinkable component A.

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and 90-10 parts by weight of a crosslinking component B, where the externally crosslinkable component A is an acrylic resin which is brittle at room temperature and has an average molecular weight 5000 - 20000 from copolymerized units

(I) 10-90% by weight of at least one ester of the acrylic and /

or methacrylic acid with 1-20 carbon atoms in the alcohol component with

(II) δ - 50% by weight of at least one hydroxyl group

tendency, olefinically unsaturated, copolymerizable Monomers

(III) 0-40% by weight of at least one unsaturated carbon

acid

(IV) Ό - 40% by weight of acrylic and / or methacrylic acid amide or

at least one N-substituted Deri-. vats of acrylic and / or methacrylic acid amide

(V) 0-50% by weight of at least one monomer from the group

pe styrene, oL-methylstyrene, acrylonitrile, Vinyl acetate, vinyl propionate, vinyl alkyl ethers with 1-8 carbon atoms in the alkyl radical, methacrylonitrile, allyl acetate, Is vinyl chloride or vinylidene chloride,

where the sum of the percentages is 100 and the sole combination of (i) and (V) is excluded and that component B is a reactive acrylic resin which cross-links with A and is soft to rubber-elastic at room temperature with an average molecular weight of 1000-5000, consists

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ORIGINAL INSPECTED

from a reaction product of a copolymer

(1) 5-80% by weight of at least one hydroxyl group

tendency monomers,

(2) 20 - 95 % by weight of at least one ester of the acrylic or

Methacrylic acid with 1-20 carbon atoms in the ester part,

(3) 0-5% by weight of at least one free cC, ß-unsaturated

Carboxylic acid with 3-5 carbon atoms,

(4) 0-50% by weight of at least one non-functional mono

meren and

(5) 0-15 wt -.% Of at least one optionally N-monoalkylated

alkylated acrylic or methacrylic acid amide

the sum of the percentages is 100, the polymer contains 0.1-50% by weight of alkoxymethyl isocyanate, based on solid Copolymer, has been implemented.

Particularly favorable results are obtained when the mixture of components A and B according to the above Definition are made up of the following monomers:

Component A: mixed polymer made of

I 10-90% by weight, preferably 10-50% by weight

Methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate or methyl methacrylate or their Mixtures,

II 0-50% by weight, preferably 5-30% by weight Le A 13 234 - 4 -

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2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, butanediol-1,4-monoacrylate or their mixtures,

III O - 40% by weight, preferably O - 15% by weight,

(Meth) acrylic acid or mixtures thereof,

IV 0-40% by weight , preferably 0-15% by weight,

(Meth) acrylic acid amide or mixtures thereof,

V 0-50 weight-96, preferably 20-50 weight-96,

Styrene or OC-methylstyrene or their mixtures,

where the sum of the percentages is 100 and the sole combination of I and V is excluded.

Component B: mixed polymer

(1) 5-80% by weight, preferably 20-40% by weight,

2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, butanediol-1,4- (j monoacrylate or their mixtures,

(2) 95 - 20 wt. 96, preferably 80 - 60 wt. 96,

Methacrylate, ethyl acrylate or 2-ethylhexyl acrylate or butyl acrylate or their mixtures and

(3) 0-5% by weight, preferably 0-3% by weight,

Acrylic acid, methacrylic acid,

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the sum of the percentages being 100 and the polymer with 0.1 - 50 wt .-! Jo, preferably 5 - 30 wt .- 96, Methoxymethyl isocyanate, based on the copolymer, reacted has been.

Specifically, among the monomers included in the groups I to V are mentioned for component A, to be understood:

Group I monomers: Aliphatic or cycloaliphatic esters of acrylic or methacrylic acid with 1-20, preferably 1 - 8, carbon atoms in the alcohol component. Examples include methyl acrylate, ethyl acrylate, n- or Isopropyl acrylate, butyl acrylate, isooctyl acrylate, dodecyl acrylate, Octadecyl acrylate, cyclohexyl acrylate and the corresponding Methacrylic acid ester.

Group II monomers are copolymerizable monomers containing hydroxyl groups, such as hydroxyalkyl esters of acrylic, Methacrylic, maleic, fumaric or itaconic acid with 2-8 carbon atoms in the alkyl radical, preferably with 2-4 carbon atoms in the alkyl radical. Examples include: hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate and the corresponding methacrylic acid esters.

Group II also includes polyvalent allyl or vinyl ethers Alcohols with 2-12 carbon atoms. The following alcohols are listed as examples: glycol, glycerine, Trimethylolpropane, erythritol, pentaerythritol, etc.

The allyl or vinyl ethers still have at least one free hydroxyl group, such as trimethylolpropane monoallyl ether or glycerol monovinyl ether.

The hydroxyalkyl esters of acrylic and methacrylic acid with 2-4 carbon atoms in the alkyl radical are preferably

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turns.

Among monomers of group III are M, ß-monoolefinic, Understood unsaturated carboxylic acids with 3-5 carbon atoms. Mention may be made of: acrylic acid, methacrylic acid, Crotonic acid, maleic acid, fumaric acid or itaconic acid, acrylic and methacrylic acid are preferred.

Acrylic or methacrylic acid amides or »N-substituted derivatives, such as N-alkyl acrylic

or methacrylamides with 1 - 8 carbon atoms in the alkyl radical, N-methylol or N-methylol ethers of acrylic and methac ryl acid amides, Mannich bases of acrylic and methacrylic acid amides or diacetone acrylamide or diacetone methacrylamide. Derivatives of acrylic or methacrylic acid amide are included sets, provided they do not cause crosslinking during the copolymerization.

Acrylic and methacrylic acid amides are preferably used.

Group V monomers are styrene, Ot-methylstyrene, acrylonitrile, Vinyl acetate, vinyl propionate, vinyl alkyl ethers with 1-8 carbon atoms in the alkyl radical, methacrylic acid nitrile, allyl acetate, Vinyl chloride or vinylidene chloride.

Preference is given to using styrene and of-methylstyrene. I.

The copolymerization of the monomers of component A is carried out by known, customary methods of emulsion, dispersion, the solution or bulk polymerization, as for example in the German patent application P 19 65 740.0, in the present application or in methods of organic chemistry, Houben-Weyl, / +, edition, 1961, vol.14 / l.

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Monomers for the preparation of the copolymer (component B) s

Monomers of group (1) are understood as meaning, for example! Hydroxymethylnorbomene, dihydroxymethylnorbornene, Phenylallyl alcohol, hydroxyalkyl ester of acrylic or methacrylic acid » like acrylic acid * or methacrylic acid hydroxyethyl * ester, -ß ~ hydroxypropyl ester, -ß-hydrQxybutyl8ster »where the Hydroxyl group can be bonded to a primary or secondary carbon atom; Hydroxyalkyl esters of the fumar or Maleic acid, such as dihydroxyethyl fumarate, monohydroxyethyl fumarate, Fumaric acid-hydraxyethyl-nathylester, Trimethylolpropane monoallyl ether, glycolraonovinyl ether.

The monomers of group (2) include, for example: acrylic acid or »methacrylic acid methyl ester, ethyl ester, -cyclohexyl ester, branched and unbranched esters of Propanols, butanols, octanols.

The monomers of group (3) include, for example: / £, ß-unsaturated carboxylic acids with 3-5 C atoms, such as acrylic acid or methacrylic acid, maleic acid, fumaric acid, itaconic acid

acid.

As monomers of group (4) are mentioned by way of example: styrene, c * -methylstyrene, vinyltoluene, acrylonitrile, vinyl acetate ,. Methacrylonitrile, ^ - chloroacrylonitrile, vinylidene chloride.

Group 5 monomers include:

Acrylamide or methacrylamide, N-methylacrylamide, N-methyl methacrylamide, N-ethyl acrylamide, N-ethyl methacrylamide.

The copolymerization of the monomers of component B is carried out by known, customary methods of emulsion, dispersion, solution or bulk polymerization, such as

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for example in German patent application P 20 05 691. 11 in the present application or in methods of organic chemistry, Houben-Weyl, 4, edition, 1961, volume 14/1.

Cj-CjQ-alkoxymethyl isocyanates are used as alkoxymethyl isocyanates of any kind, especially methoxymethyl isocyanate, ethoxymethyl isocyanate, isopropoxymethyl isocyanate, butoxymethyl isocyanate, Hexoxymethyl isocyanate, preferably methoxymethyl isocyanate.

The reaction of component B with the alkoxymethyl isocyanates takes place according to known customary methods in substance or solution, for example according to the German Auslegeschrift 1 244 410, The reaction with the alkoxymethyl isocyanates can also take place before the copolymerization or else the monomers containing OH and NH groups can be mixed with the Isocyanates reacted, mixed with the other monomers and then copolymerized.

The mixing of the elasticizing reactive component B with the brittle component A can be in solution or in bulk in a stirred tank, in a screw, an internal mixer or in a kneader at temperatures of approx. 20 - approx. 130 ° C take place. The choice of the mixing temperature depends on whether it is mixed in bulk or in solution. Here must It should be noted that temperatures of about 110 ° to over 130 ° C may only be used for a short time, as longer thermal stress crosslinking can occur.

There are 90-10 parts by weight of the soft elastic component B with 10-90 parts by weight of the brittle and hard Component A mixed.

The binders according to the invention consist of two components - Le A 13 234 - 9 -

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th, from a soft, elasticizing component and from a hard and brittle component. The elasticity of a resin is given by the mobility of the molecular chains · Brittle resins have few mobile chains, which are mostly through Secondary valence forces and crystalline areas are hindered in their mobility. The soft elasticizing component from a molecular weight of 1000 to 5000 with their mobile molecular chains carries N-alkoxymethyl urethane groups and reacts during the baking process with the NH or OH groups of brittle and hard components with a molecular weight of 5000 to 20,000, after the baking process there is a network, the mesh of which is made up of two different segments, from relatively short-chain elasticizing segments and from longer-chain, brittle parts. The highly cross-linked coatings present in the baking process with this segment-like structure surprisingly show a high surface hardness with excellent elasticity at the same time, It is also possible to first convert the hard, brittle component A into the alkoxymethyl urethane with an alkoxymethyl isocyanate to transfer them to then with the free OH or NH groups of a soft elasticizing component B to react during the burn-in process. The segment-like structure is also retained. This way but does not have the same meaning as the inventive, since it is technically easier to implement to convert the soft elasticizing component B into the alkoxymethyl urethane convict.

The excellent application properties of the binders according to the invention, which are determined on the cured films, are not achieved if the Komr Component A is used alone as a binder, nor is component B used on its own. These properties can also not be found on films of a binder that

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Jt 21, Π054

by simultaneous copolymerization of all monomers in Component Λ and component B are contained, were extracted. This applicant tries these facts from the comparison can be seen * are extremely surprising.

In addition, it is also possible to mix the substances according to the invention Prepare binders by first making one of the components, either A or B, as usual and then the monomer mixture of the other resin B or A in the presence of the initially introduced and polymerized resin A or, B polymerized, with the help of the usual radical formers, like peroxides »peresters or azo compounds. This particular Ausführungsforra has the advantage that a subsequent Mixing the components is unnecessary, Also the components, mixed in this way, show an even more better tolerance, what by a; partial graft polymerization may have been caused! times the reaction with an alkoxymethyl urethane and after the baking process the segment-like structure of elastic and brittle segments is retained.

The soft »elasticizing acrylic resins B of this application cannot be pulverized at room temperatures. The hard, brittle component A can be pulverized at room temperature.

The special properties of acrylic resins, such as softness, Brittleness or elasticity are determined by the average molecular weight, which is determined osmometrically, and determined by the monomer composition. The molecular weight will in a manner known per se with the aid of regulating additives, such as mercaptans, over the polymerization temperature and over

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ORIGINAL IMSPECTED

the stationary concentration of the initiator radicals adjusted to the desired size, d. H. 5,000 to 20,000 for the brittle component A and 1000 to "5000 for the elastic component B.

As already described, components A and B can be mixed in bulk or in solution by customary methods will. If the mixture is mixed in solution, the usual paint solvents, such as aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, esters, ketones, ethers can be used. Examples which may be mentioned as solvents or diluents;

Aromatic hydrocarbons such as toluene, xylene, chlorobenzene; Carboxylic acid esters, such as ethyl acetate, butyl acetate, glycol monomethyl ether acetate and glycol monoethyl ether acetate; Ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; Alcohols such as ethanol, butanol, ethylene glycol, butylene glycol1, Ethylene glycol monobutyl ether, monomethyl ether, monoethyl ether. Mixtures of the aforementioned solvents can also be used can be used.

The solid binders, for example in powder form, can be extracted from the solutions - by evaporation in a screw and subsequent grinding, for example, according to the method of German patent application P 20 05 691 »1. For extraction Precipitation processes can also be used for powders from the solutions of the binders. But the solutions can do it can be used directly as a coating agent.

The binders according to the invention can contain conventional auxiliaries in the solid or dissolved state, such as pigments, fillers, soluble organic dyes, catalysts, leveling agents are added, namely soluble organic dyes

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Fe, catalysts and leveling agents (such as cellulose acetobutyrate) in amounts of 1 to 50 Gev /, -%, based on solid binder.

Pigments and fillers can be used in amounts of 5 to 200 parts by weight, based on 100 parts by weight of solid binder, are used.,

For example, white and colored pigments are used as pigments in Frages such as titanium dioxide, chromium oxides, iron oxides, zinc oxides, Mixed oxides of cobalt, nickel and manganese; Selenides and sulfides of zinc and cadmium, such as zinc sulfide, cadmium sulfide, Cadmium sulfide selenides; Chromates, such as zinc, lead or strontium chromate, chrome yellow, Prussian blue, Brunswick Green, lithopone, organic pigments such as phthalocyanine pigments or insoluble azo dyes.

Fillers include: precipitated or thermally obtained silicas, silicates, talc, mica, quartz powder, Barium sulfate, calcium sulfate, aluminum oxide, glass powder and others.

The pigments can be blended with the fillers.

To achieve anti-corrosive and decorative effects, the paints can contain aluminum bronze and zinc dust contain. Such "metallic effect paints" have an extremely good weather resistance, the binders are therefore preferably used for metal effect coatings.

The coating agents produced with binders according to the invention come in powdered or dissolved form for use, whereby in the case of the solution the already mentioned solvents are used.

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The coating agents can be applied according to the various known techniques of spraying, dipping, spraying and painting. applied to the object to be coated _s such as electrostatic spraying processes, fluidized bed _{sintering processes s flame spraying processes, etc.}

The baking temperatures can be 12 ° to 350 ° C., preferably 130 ° C. to 300 ° C. = The baking time depends on the type of composition of the binder and is generally between 30 seconds and 60 minutes.

If the erfindungsgemSßen Misobuagen nstoff- hür-with or Melaminformaldshyäharzen in quantities you 5 to 40 parts by Yes with _0? 5 to 6 wt .-? ^ Of an acidic catalyst, always based on 100 % solid mixture; mixed, after the linbremisa m-mr no improvement in the lacquer coating properties is achieved, surprisingly, sioii /, but the linfcrenntemp era doors on TsBiperatures below 3ΰ ^ν '- C _r . preferably - 6ö - 80 ° C, lower. Yorauasetsung rl ^ 'b Ji.'lsr- · at j that the B (1) set up with alkoxy "ffiethyD-isocy £ .nat is a primary hydroxyl group containing ο

The same lowering of the baking temperature can be achieved achieve what in the mixtures according to the invention Component / (IV) an N-methylol compound or an N-methy lol alkyl ether of (meth) acrylamide is component B (1) consists of one or more monomers with primary hydroxyl groups and 0.5 to 6% by weight of an acidic catalyst, based on solid polymer mixture, are added «,

The coating compositions produced with the binder according to the invention find versatile use. Because of your

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Strength, elasticity with simultaneous high surface hardness and good chemical and weather resistance they are suitable as equipment paints, can interior paints, as Automotive enamels, wire enamels and as fluorescent paints. she are preferably used for the production of chemical-resistant protective coatings and for metal strip coating and production of metal effect paints using the wet-on-wetr process. Sheets coated with the paint mixtures according to the invention can be deformed and folded.

Although preferably objects made of metals, for example steel, cast steel, copper, brass, bronze, gunmetal, aluminum and its alloys are coated or coated, the means can also be used for coating or Covering objects made of glass, ceramics, porcelain and plastics are used.

To characterize the properties of the paint mixtures according to the invention and to describe them further, let the following examples are given. The parts and percentages given in the examples relate to the weight, unless otherwise stated.

Manufacture of the hard component A.

Binder A 1

In a stirring pot equipped with a helical stirrer, the Nitrogen a mixture of 375 g of styrene, 165 g of ethylhexyl acrylate, 150 g of 2-hydroxypropyl methacrylate, 165 g Acrylic acid amide, 30 g tert. Dodecyl mercaptan, 100 g of xylene, 100 g of methyl glycol acetate and brought to 130.degree. Within one hour, 10.5 g of tert are stirred while cooling. Butyl perpivalate as a 75% solution in white spirit (Kpyg «: up to 150 ° C). The internal temperature should rise to 140 ° C. Then 7 g of di-tert-butyl peroxide are added in one hour

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added dropwise. After a further hour, the volatile constituents are distilled off in vacuo at 160 ° C. and the paint melt is poured onto a metal sheet. After cooling, the result is a hard, easily pulverizable resin with a molecular weight of 7000. The resin can be dissolved up to 50% in xylene.

Binder A 2

1000 g of ethyl glycol acetate are placed in a stirring pot and a mixture of 400 g of styrene, 300 g of butyl acrylate, 100 g of methyl methacrylate is added dropwise to this at 130 ° C. over the course of 5 hours and 200 g of 2-hydroxypropyl methacrylate, 1 g of methacrylic acid and 15 g of tert-butyl peroctoate are added. Then left for 5 hours at 130 ° C and distilled the volatile constituents at 250 ° C and 2 mm Hg on the thin film evaporator. The hot melt solidifies a brittle resin with an average molecular weight of 5900 and an OH number of 76.

Binder A 5

A mixture of 600 g of butyl glycol, 60 g of acrylamide, 30 g of acrylic acid, 60 g of 1,4-butanediol monoacrylate, 180 g of methyl acrylate and 360 g of ethyl acrylate is prepared. 300 ml of the mixture are brought to 100 ° C. in a flask and the polymerization is started under nitrogen with a few drops of tert-butyl peroctoate. The remainder of the mixture is then added over the course of 6 hours, together with 12 g of tert-butyl peroctoate, and the mixture is stirred for a further 5 hours. After evaporation, a sample is obtained a hard resin at room temperature having an average molecular weight of 9000. This paint is particularly suitable in connection with the component B 2 for metal strip sprays ₀

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Production of the elasticizing component B

Binder B 1

300 g of 1,4-butanediol monoacrylate, 700 g of 2-ethylhexyl acrylate and 20 g of tert-dodecyl mercaptan presented and heated to 150 ° C. 7 g of tert-butyl perpivalate as a 75% solution in Butyl phthalate and lets the temperature rise to 170 ° C. Thereafter, within a further hour, 7 g Stir in di-tert-butyl peroxide. The volatile constituents are removed at 180 ° C. by applying a vacuum and cooled to 60 ° C. while stirring with a helical stirrer. 120 g of methoxymethyl isocyanate are then stirred in and, after 2 hours, the mixture is cooled to room temperature. The viscous resin is then taken up in xylene or butyl acetate. The osmometrically determined molecular weight is 3300 measured in acetone.

Binder B 2

700 g of xylene are placed in a stirred pot under nitrogen and refluxed for this purpose over the course of 3 hours a mixture of 300 g butanediol monoacrylate, 700 g ethyl acrylate, 15 g of tert-dodecyl mercaptan and 15 g of tert-butyl peroctoate were added dropwise. The mixture is then stirred for a further 5 hours after, cools to 45 ° C., 0.5 g of tin dioctoate is added and 175 g of methoxymethyl isocyanate are stirred in. After 12 hours and At 45 ° C., 300 g of n-butanol are added and the mixture is cooled. To after careful evaporation, a rubber-elastic film with an average molecular weight of 3600, measured in acetone, remains.

Binder B 3

Production as for B 1, but instead of butanediol-1,4-monoacrylate, 300 g of methacrylic acid-2-hydroxyethyl-

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ester used. A reactive resin with a molecular weight of 3500 * is syrupy at room temperature.

Production of the paint mixture by polymerizing the monomers of the hard component A in the presence of the polymerized soft component · Β

Binder C

1000 g of component B 1 (see above), but not yet reacted with methoxymethyl isocyanate, are iri one Mixture of 500 g of styrene, 300 g of butyl acrylate and 200 g of 2-hydroxypropyl methacrylate dissolved. The mix will brought to 130 ° C and within one hour 7 g of tert-butyl perpivalate Stirred into white spirit as a 75% solution. The temperature rises to 160 ° C. 7 g of di-tert-butyl peroxide are then added and the volatile constituents are removed after a further hour in a vacuum at 170 C.

The still hot paint melt is e

ο
reacted at 120 ° C. and a residence time of 4 minutes with 6% by weight , based on the resin mixture, of methoxymethyl isocyanate. The melt modified in this way is allowed to solidify. After dissolving in xylene, the resin can be used for metal effect coatings (molecular weight of binder C: approx. 6600).

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example 1

To produce a stoving enamel suitable for continuous metal strip painting, 100 parts of the solution of binder A3 in butyl glycol (as described under binder A3) are mixed with 30 parts of the solution in binder B2 - as indicated under binder B2 and pigmented by rubbing through a funnel mill with 100 % titanium dioxide rutile type (based on the solids content of the mixture). The white lacquer can be seen with a hand coater on degreased iron sheets and burned in without flashing off. The properties of the cured paint films are shown in the following table:

Stoving conditions: 90 sec layer thickness

Beat! Efung after Gardner (inch / pound)

Pencil hardness DIN 46 453 cross-cut DIN 53 151 T-bend test

Examination according to the Journal of

Paint Technology 40 (1968)

P. 58 A

Erichsen recess DIN 53 156

Surface hardness / scratch resistance

shine

The Lackxilme are well resistant to toluene and have a excellent resistance to weathering in Florida climate.

Example 2

The one described as binder A 1 containing hydroxyl groups

- 260 ° C 60 sec. Well - 300 ° C 20 / u Well 20 yes 80 80 HB HB 1 1 1 1 1/2 9.8 (sheet metal crack) 9.5 'Λ. Well Well

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Lacquer resin is dissolved in xylene and mixed with the component described as binder B 2 so that the ratio of the two substances is 10: 3 and the resulting solution is 50 % . 1000 parts of this solution are pigmented with 250 parts of titanium dioxide of the rutile type in a funnel mill, diluted with xylene to spray viscosity and the paint is sprayed with a compressed air spray gun onto body panels that have been treated with a commercially available epoxy primer and burns in after brief ventilation. The properties of the top coat are shown in the following table:

Stoving conditions
Layer thickness of the top coat according to Gardner (inch / pound)
Pencil hardness DIN 46 453

Erichsen recess DIN 53 156 Mandrel Flexure Test ASTM D 522-41 Gardner Gloss ASTM D-523-536 Solvent Resistance 5 min. - Xylene at room temperature then 20 min. Storage in the air resistance

in the Sun-shine Weatherometer XW after 700 hours no

ne chalk good gloss retention-

Example 3

30 min. ■ - 120 ° C 45 μ 20th 3 H 5, , 9 1, , 0 cm cracks 97 slightly marked unchanged

To produce a metallic effect paint that is to be applied in the two-coat system "wet on wet", the acrylate mixture given in Example 2 is used and 15 % hexamethoxymethylamine and 1 % p-toluenesulfonic acid (based on the solids) are added to the solution. Part of the mixture is then pigmented with a 50% xylene paste

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Commercially available very fine aluminum bronze, adds paint auxiliaries (flow control agent, plasticizer) 2u, diluted with isopropanol to spray viscosity (DIN 4 cup i4 see). Then you spray on smooth, degreased iron sheets and briefly ventilate.

Then the unpigmented clear lacquer, which is also diluted to spray viscosity, is applied with a second spray gun is sprayed on and baked at 120 ° C for 30 minutes. A very bright, uniform metallic effect is obtained. The sheets are practically unchanged after 1 year of storage in a maritime climate.

Comparative example 1 versus example 2

This example demonstrates that films of an interpolymer of the gross composition according to Example 2 are not the same like Abmir.chung films have favorable properties in terms of surface hardness, gloss and elasticity of example 1.

165 g of acrylic acid amide, 150 g of 2-hydroxypropyl methacrylate, 165 g of ethylhexyl acrylate, 375 g of styrene (monomers of component Al), 77 g of butanediol-l ^ -monoacrylate λ and 180 are added in sequence to a 3 liter glass flask with a spiral stirrer g of ethyl acrylate (monomers of component B 2) and 20 g of tert-dodecyl mercaptan. The contents are heated to 120 ° C. under nitrogen and polymerized by adding dropwise 10 g of tert-butyl perpivalate, dissolved in 20 g of dichloroethane, over the course of 3 hours. The temperature rises to 160 ° C. 4 g of di-tert-butyl peroxide are then added dropwise and the mixture is cooled after a further one

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λ ι η ο 1 1

211005A

Hour to 110 ° C. 46.5 g of methoxymethyl isocyanate are stirred in and after a further 5 minutes it is diluted with butyl glycol a solids of 50%. The cooled paint is disfigured with 50 parts by weight of titanium dioxide, based on 100 parts by weight of solid product, rubbed and according to example 2 on body panels sprayed on. The properties of the top coat are shown in the following table:

Stoving conditions 30 min. - 120 ° C

Layer thickness 45 pi impact drag inch / pound 6

Erichsen recess DIN 53 156 3.0

Mandrel bending test 2.0 cm cracks

Pencil hardness H The gloss is obscured.

Comparative example 2

In comparison to Example 1, in which two binders A 3 and
3 2 were combined, binders A 3 and B 2
tested separately according to example 1.

Both binders are, as indicated in Example 1, with
100 % titanium dioxide rutile type rubbed off and baked. the
Properties of the paint films are in the table below
specified. It can be seen from this that both binders alone do not achieve the valuable properties of their mixture by far.

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(C.

OJ

O i co ro as cn c (O

Burning Conditions

Layer thickness pencil hardness

DIN 46 453

Gardner impact depth (inch / pound)

T-bend test Erichs Enti efung

DIN 53 156

Cross-cut

DIN 53 151 (May 1955)

Scratch resistance / surface

shine

Persistence of

Piliae versus toluene

Binder B

90 see - 260 ° C

20 / rev

<6 B

60 sec - 300 C

20 / u

<6B

because of the stickiness of the surface and the insufficient hardness of the film, none could Measurements are carried out

good i good

Toluene completely removes the paint film from the metal sheet from binder A

90 sec - 260 ⁰ C 20 _{/ rev}

1 1/2

small amount
Well

60 see - 30O ⁰ C

20 2 B

1 1/2

8.8 1

little good

Films in toluene initially swell - very strongly, lift themselves and dissolve

Example "4

The following Examples 4 to 12 demonstrate that the invention Mixtures, if mixed with melamine-formaldehyde resins and an acidic catalyst, already can be stoved at temperatures of 80 ° C to form solvent-resistant and scratch-resistant coatings.

A prerequisite, however, is that the copolymer mixture has copolymerized units of a primary hydroxyl group Contains monomers, the primary hydroxyl groups fully or partially reacted with an alkoxymethyl isocyanate have been. In the following examples, a component containing methylmethyiol urethane is used as such a component Acrylic resin used, which consists of polymerized units of a butanediol-1,4-monoacrylate or a ß-hydroxyethyl methacrylic acid ester and subsequent reaction with methoxymethyl isocyanate has been obtained.

In a 40-liter kettle, 17 kg of xylene and 6 kg are put under nitrogen. Butanediol-l ^ monoacrylate, 14 kg of ethyl acrylate and 300 g of acrylic acid submitted »The mixture is heated to reflux temperature and 300 g of tert is added dropwise over the course of 3 hours. Butyl peroctoate added. 100 g of di-tert-butyl peroxide are then added and the mixture is refluxed for 8 hours. The mixture is cooled to 50 ° C., 10 g of tin dioctoate are added and 95 % of methoxymethyl isocyanate, based on butanediol-l ^ monoacrylate, are stirred in. After about 30 minutes, 3 kg of methanol are stirred in and the mixture is cooled to room temperature.

The adjusted to 50% solids solution in a weight ratio of 3: 10 with a 50% ± gen solution of a commercial self-crosslinking acrylic resin consisting of 25 wt .-% styrene, 45 wt, -% ethyl acrylate, 10 wt _o -% ethylhexyl acrylate, 10 wt .-% methacrylic acid-ß-hydroxypropyl ester, 10 wt .-% acrylamide in a xylene-butanol mixture 2: 1 (weight ratio).

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mixed and with 15%, based on solid acrylic resin, hexamethoxymethylmelamine and 3 wt .-% tartaric acid added. Equal parts, based on the solid content of titanium dioxide, are now of the rutile type The paint is mixed in on a roller and diluted to spray viscosity with xylene (flow time: 45 seconds, DIN 4 cup) and on primed body panels (thickness of the primer: 30 vu) sprayed on. The lacquers are baked after a short flash-off, namely 30 minutes at 80 ° C. The films have the following properties Characteristics:

Stoving conditions Layer thickness of the top coat

Gardner impact depression (inch / pound)

Mandrel bending test according to ASTM D-522-41

Pencil hardness

Cross-cut test DIN 53 151

Surface hardness

(Fingernail test)

Gardner ASTM D 523-536 gloss

Erichsen recess DIN 53 156

Solvent resistance

6 min. - xylene at room temperature

then 2 hours of regeneration in the air

30 min, 80 ° C 50 / u

not cracked 3H

no damage to the paint surface 97
7 mm

slightly marked unchanged.

Examples 5 to

For the production of acrylic resins with methyl methyl urethane groups of primary alcohols (soft component B) (Examples 5 to 7) are the monomers and solvents together heated to reflux temperature under nitrogen using the regulators given in the table below. Within 3

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Hours are added dropwise 20 g of tert-butyl peroctoate and stirred until the solids content of 50 % is reached. Existing moisture is removed by brief distillation. Then at 60 ° C. 95 mol%, based on β-hydroxyethyl methacrylate, of methoxymethyl isocyanate and 0.6 g of tin dioctoate are stirred in. After 30 minutes, 50 g of isopropanol are added to the mixture.

Example 5 Example 6 Example 7

Xylene 1000 g 1000 g 1000 g

Ethyl acrylate 700 350 methyl acrylate 420

Butyl acrylate 280 350

§ Mejhacrylic acid-ß- _{300 300 300} hydroxyethyl ester ^ ^

tert-dodecyl mercaptan 15 10 ¹⁰

The solvents, monomers and regulators are used to produce the externally crosslinking acrylic component (hard component A) of Examples 8 to 12

8th Examples 9 10 11 12th '600 600 600 600 600 Xylene 400 400 400 400 400 Isopropanol 250 375 375 375 250 Styrene 165 165 165 165 165 Acrylamide 150 150 150 150 150 Methacrylic acid-ß-
hydroxypropyl ester - 310 - 145 135 Ethyl acrylate 295 - 200 - - Methacrylate 140 - 110 - 200 Butyl acrylate - - - 165 100 Ethylhexyl acrylate

terto-dodecyl mercaptan 20 20 20 20

mixed and heated to 80 ° C. The mixture is still hot filtered. About 200 ml of this mixture are made under nitrogen

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placed in a 3 liter flask. Is under reflux the remainder of the mixture is pumped in warm (about 40 "to 60 ° C.) within 5 hours and at the same time 15 g of tert-butyl peroctoate added dropwise. The internal temperature is then brought to 100 ° C., 5 g of tert are added. Add butyl peroctoate and stir 100 ° C for 5 hours. The paint solution is clarified using a pressure filter.

To produce a paint that can be baked at 80 ° C., the solutions from Examples 5 to 7 are each mixed with solutions from Examples 8 to 12 so that 10 parts by weight of solids from Examples 8 to 12 account for 3 parts by weight of solid from Examples 5 to 7 . Based on the solids of the mixture, 15 % hexamethoxymethylmelamine and 3 % tartaric acid are added and pigmented as described in Example 4 and applied to primed body panels.

The binders of Examples 5 to 7 can be reduced. Mixing with 15 wt .-% hexamethoxymethylmelamine and 3 % tartaric acid according to the conditions of Example 4 at 80 ° C within 30 minutes to bake solvent-resistant coatings, but the films have insufficient surface hardness (pencil hardness worse than HB).

The binders of Examples 8 to 12 give, after addition of 15 wt -.% Hexamethoxymethylmelamine and 3 wt .-% tartaric acid within 30 minutes at 80 ° C films that are not solvent resistant. After 6 minutes of placing a cotton ball soaked in xylene, they become detached from the body panel.

The following table lists the lacquer technical data of films of mixtures according to the invention (Examples 5 to 12), which, after adding hexamethoxymethylmelamine and tartaric acid, were stoved for 30 minutes at 80 ° C.

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Stoving condition Layer thickness of the top coat

Gardner impact depression (inch / pound) Mandrel bending test according to ASTM-D-522-41 pencil hardness

Cross-cut test DIN 53 151

Surface hardness (fingernail test) Gloss according to Gardener ASTM D 523 - 536 Erichsen recess DIN 53 156

Solvent resistance 6 minutes-xylene at room temperature

then 2 hours of regeneration in the air

If

Binder mixture from Examples 7 and 11 5 and 12 6 and 9

30 min. 80 ° C 30 min. 80 ⁰ C for 30 min. 80 C ⁰

approx. 50 / rev

16

not torn

approx. 50 / rev

18th

not
cracked

approx. 50 / rev

16

not torn

no damage to the paint surface 96 93

6.6 mm

slightly marked

6.5 mm

easy
marked

6.4 mm

slightly marked

unchanged unchanged unchanged

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Claims (1)

Claim: Binder for coating compounds for metals, consisting of a mixture of 10 - 90 parts by weight of an externally crosslinkable Component A and 90-10 parts by weight of a crosslinking component B, the externally crosslinkable Component A is an acrylic resin which is brittle at room temperature and has an average molecular weight of 5,000 - 20,000 made from copolymers units (I) 10-90 wt -.% Of at least one ester of acrylic and / or methacrylic acid with 1-20 carbon atoms in the alcohol component with (II) 0-50% by weight of at least one hydroxyl group ent containing, olefinically unsaturated, copolymerizable monomers (III) 0 - 40 wt .-? 6 of at least one unsaturated carbon acid (IV) 0 - 40 wt -.% Acrylic and / or methacrylic acid and at least one N-substituted derivative of acrylic and / or methacrylic acid amide (V) 0-50 wt .- # of at least one monomer from the group pe is styrene, U -methylstyrene, acrylonitrile, vinyl acetate, vinyl propionate, vinyl alkyl ether with 1-8 carbon atoms in the alkyl radical, methacrylonitrile, allyl acetate, vinyl chloride or vinylidene chloride, Le A 13 234 ~ 29 - 0 9 8 51/0911 where the sum of the percentages is 100 and the only one Combination of (I) and (V) is excluded and that component B is a crosslinking with A and at room temperature soft to rubber-elastic reactive acrylic resin from mean molecular weight 1000-5000, consisting of a reaction product of a copolymer from (1) 5-80 -.% Of at least one hydroxyl group contained tendency monomers, (2) 20 - 95 wt .- # of at least one ester of the acrylic or Methacralic acid with 1-20 C atoms in the ester part, . (3) 0-5 wt -% of at least one free ct, ß-unsaturated Carboxylic acid with 3-5 carbon atoms,, (4) 0-50 wt -.% Of at least one non-functional mono meren and (5) 0-15 wt -.% Of at least one optionally N-mono- alkylated acrylic or methacrylic acid amide the sum of the percentages is 100, the PolymerisaT0FLst with 0.1 - 50 wt. 96 alkoxymethyl isocyanate, based on solid Copolymer, has been implemented. Le A 15 234 - 30 - 209851/0911 INSPECTED