Binder combination with a high solid content

The invention relates to new, OH-functional binder components based on polyacrylate, a process for their preparation and their use for the production of coatings.

By combining the OH-functional binder components essential to the invention with polyisocyanates, new, high-solid binder combinations are obtained which can be cured into high-quality coatings. In addition to excellent film optics as well as high resistance to solvents and chemicals, these coatings exhibit very fast physical drying and chemical crosslinking at room temperature as well as good surface hardness.

The advantage of high-solids polyacrylate resins is the reduction in the emission of organic compounds, preferably solvents, when the lacquer is applied. In order to obtain these high-solids paint formulations, appropriate polyacrylate resins with low viscosities, ie low molecular weights, must be used.

It is known that free-radical solvent polymerization can be used to prepare low-viscosity polymers (for example EP-A 408 858, EP-A 398 387, US Pat. No. 4,145,513). It is partly disadvantageous that the properties of the polymers are impaired by the use of considerable amounts of polymerization regulators and their secondary products. In particular, the thiols used as polymerization regulators can smell bad or even be toxic. In EP-A 225 808 or EP-A 225 809 are therefore α-olefins, such as. B. 1-octene or 1-decene, which have no unpleasant smell, used as a regulator. However, 2-component PUR coatings based on the polyacrylate resins according to EP-A 225 809 and aliphatic coating polyisocyanates have too slow physical drying for use in automotive repair and large vehicle painting.

EP-A 635 523 and EP-A 638 591 describe high-solids polyacrylate resins which are prepared by bulk (substance) polymerization and then diluted with a suitable solvent. From EP-A 635 523 it is known to transfer the effect of the production of unimodally narrowly distributed, high-solids polyacrylate resins known from solvent polymerization when using peroxides containing tertiary amyl groups to the polyacylates produced in bulk polymerization. It could be demonstrated that peroxides bearing tert-amyl groups lead to lower-viscosity polyacrylate resins than peroxides containing tert-butyl groups. However, the advantages of bulk polymerization compared to solvent polymerization cannot be clearly recognized. The polyacrylate resins produced have a solids content of 70% by weight viscosities at 23 ° C between 2,790 and 9,130 ​​mPa.s, are therefore in the medium-solid range and therefore do not meet today's requirements for high-solids paints.

EP-A 638 591 describes high-solids copolymers which, by using (meth) acrylate monomers with sterically demanding (cyclo) alkyl radicals, have a relatively low viscosity with a high solids content. In the preparation of these copolymers by bulk polymerization, a monoepoxide (Cardura E 10®) is presented as the reaction medium in all of the examples listed. This monoepoxide reacts with the metered (meth) acrylic acid during the polymerization and is thus incorporated into the polyacrylate. This reaction produces predominantly secondary hydroxyl groups which, in addition to the primary hydroxyl groups (hydroxyethyl methacrylate) or secondary hydroxyl groups (hydroxypropyl methacrylate) introduced by hydroxy-functional monomers, are available for the reaction with the polyisocyanate used as crosslinker.

Secondary hydroxyl groups have a significantly lower reactivity to polyisocyanates than primary hydroxyl groups. For this reason, 2-component PU coatings based on polyacrylate resins with predominantly secondary hydroxyl groups only reach a sufficient crosslinking density after a number of days and, associated with this, a satisfactory resistance to solvents. In car repair and large vehicle painting, however, in addition to rapid physical drying, rapid chemical crosslinking is also necessary to enable the vehicle to be used again quickly.

It was therefore the task to provide new hydroxy-functional copolymers by the simple solvent polymerization process which, in combination with (cyclo) aliphatic paint polyisocyanates, provide high-solids paints which, in addition to rapid physical drying, also show rapid chemical crosslinking. In contrast to coatings with known paints, the new high-solids paints should be able to achieve high-quality coatings which, after a curing time of only a few days, have excellent solvent resistance and thus enable the vehicle to be used quickly.

It has now been found that paints based on combinations of binders composed of special graft copolymers and polyisocyanates with a high solids content have a very high solids content in the ready-to-process state. These lacquers provide coatings that have a very fast physical drying and rapid chemical crosslinking at room temperature (23 ° C), ie excellent solvent resistance after only 1 to 2 days. The very good overall property profile of the paint films obtained, such as hardness, elasticity, chemical and weather resistance, allows use in vehicle painting, preferably in automotive repair and large vehicle painting. Further areas of application are in the area of ​​corrosion protection and wood and furniture painting.

The invention relates to combinations of binders<ul id="ul0001" list-style="none"><li>A) 95 to 40 parts by weight, preferably 90 to 50 parts by weight of OH-functional graft copolymer resins, prepared by copolymerization of<ul id="ul0002" list-style="none"><li>a) 0.1 to 10 parts by weight of at least one optionally functional polybutadiene with a molecular weight of <maths id="math0001" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0778298A2_D0001.tif" /></maths>n 500 to 10,000 and with at least 20% 1,2-vinyl structure,</li><li>b) 5 to 30 parts by weight of at least one aliphatic α-olefin having 8 to 16 carbon atoms,</li><li>c) 10 to 70 parts by weight of at least one unsaturated aromatic monomer such as styrene, α-methylstyrene or vinyltoluene,</li><li>d) 5 to 60 parts by weight of at least one hydroxyalkyl ester of (meth) acrylic acid having 2 to 4 carbon atoms in the hydroxyalkyl radical and primary bound hydroxyl group,</li><li>e) 0 to 50 parts by weight of at least one (cyclo) aliphatic ester of acrylic and / or methacrylic acid with 1 to 12 carbon atoms in the alcohol component,</li><li>f) 0.1 to 10 parts by weight of at least one α, β-monoolefinically unsaturated mono- or dicarboxylic acid with 3 to 7 carbon atoms and / or at least one maleic or fumaric acid semester with 1 to 14 carbon atoms in the alcohol radical,</li><li>g) 0 to 30 parts by weight of other copolymerizable, olefinically unsaturated compounds and</li></ul></li><li>B) 5 to 60 parts by weight, preferably 10 to 50 parts by weight, of a multi-functional crosslinking resin, for example amino resins, such as alkoxylated melamine resins, melamine-formaldehyde condensation products, urea resins, guanidine resins, phenolic plastic resins, resol resins and, preferably, blocked, polyfunctional resins Isocyanates, preferably oligomeric isocyanates with a biuret, allophanate, uretdione, urethane and / or isocyanurate structure,</li></ul> the sum of the parts by weight of components A) and B) and the sum of the parts by weight of components a) to g) being 100 in each case.

The invention also relates to the use of the binder combinations according to the invention in vehicle painting, in particular car repair and large vehicle painting, in wood and furniture painting and in the field of corrosion protection.

The chemical composition of the graft copolymers A) of the binder combinations according to the invention differ significantly in their chemical composition both from the polyacrylate polyols of EP-A 225 809 and from the substance copolymers of EP-A 635 523 and EP-A 638 591. With regard to the paint properties, in particular the drying speed and the resistance to solvents, there are advantages over the products of the documents mentioned, as is demonstrated in corresponding comparative examples.

The graft copolymer resins A) essential to the invention can be prepared by copolymerizing constituents a) to g) by customary processes. Radical polymerization in solution is preferred. Here, monomeric and oligomeric building blocks are copolymerized at temperatures of 140 to 240 ° C in the presence of radical formers.

Preferred starting compounds for the polyacrylate resins A) consist of:<ul id="ul0003" list-style="none"><li>a) 0.3 to 7.5 parts by weight of one or more, optionally functional, polybutadienes with a molecular weight <maths id="math0002" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0778298A2_D0002.tif" /></maths>n from 500 to 5,000 and at least 30% 1,2-vinyl structure,</li><li>b) 5 to 25 parts by weight of at least one α-olefin having 8 to 12 carbon atoms,</li><li>c) 15 to 65 parts by weight of styrene,</li><li>d) 7.5 to 55 parts by weight of hydroxyethyl acrylate, hydroxyethyl methacrylate, butanediol-1,4-monoacrylate or mixtures thereof,</li><li>e) 0 to 45 parts by weight of at least one (cyclo) aliphatic ester of acrylic and / or methacrylic acid with 1 to 10 carbon atoms in the alcohol component,</li><li>f) 0.3 to 8 parts by weight of acrylic acid, methacrylic acid, maleic acid or fumaric acid semiesters with 1 to 8 carbon atoms in the alcohol component or mixtures thereof and</li><li>g) 1 to 25 parts by weight of acrylonitrile, methacrylonitrile, hydroxypropyl (meth) acrylate (up to 10 parts by weight), vinyl esters of aliphatic, optionally branched moncarboxylic acids with 1 to 10 carbon atoms in the acid residue, di (cyclo) alkyl esters of maleic and / or fumaric acid with 1 to 8 carbon atoms in the alcohol residue or mixtures thereof,</li></ul> the sum of the parts by weight of components a) to g) being 100.

Particularly preferred starting compounds for the polyacrylate resins A) consist of:<ul id="ul0004" list-style="none"><li>a) 0.5 to 5 parts by weight of one or more, optionally functional, polybutadienes with a molecular weight <maths id="math0003" num=""><math display="inline"><mrow><mover accent="true"><mrow><mtext>M</mtext></mrow><mo>¯</mo></mover></mrow></math><img file="EP0778298A2_D0003.tif" /></maths>n from 500 to 3,000 and at least 40% 1,2-vinyl structure,</li><li>b) 5 to 20 parts by weight of 1-octene, 1-decene or mixtures thereof,</li><li>c) 20 to 65 parts by weight of styrene,</li><li>d) 10 to 50 parts by weight of hydroxyethyl acrylate, hydroxyethyl methacrylate or mixtures thereof,</li><li>e) 0 to 35 parts by weight of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate or mixtures thereof,</li><li>f) 0.5 to 5 parts by weight of acrylic acid, methacrylic acid or mixtures thereof and</li><li>g) 3 to 20 parts by weight, vinyl esters of aliphatic, optionally branched monocarboxylic acids with 3 to 9 carbon atoms in the acid residue, di (cyclo) alkyl esters of maleic and / or fumaric acid with 1 to 8 C atoms in the alcohol residue or mixtures thereof,</li></ul> the sum of the parts by weight of components a) to g) being 100.

Basically all polybutadienes which have at least 20% pendant 1,2-vinyl double bonds are suitable as starting materials a) for the graft copolymers A) which are essential to the invention.

Polybutadienes with a vinyl double bond content of ≥ 30% are preferred. The rest of the double bonds can consist of any ratio of 1,4-cis and 1,4-trans structure. Polybutadienes, which also have double bonds in cyclic structures, are also suitable as component a). A particularly suitable starting material is a product with ≥ 40% 1,2-vinyl double bonds.

In general, mixtures of isomers of polybutadienes will be used, e.g. B. polybutadienes, which have 30 to 90% 1,2-vinyl double bonds, 10 to 70% mixtures of 1,4-cis and 1,4-trans double bonds and 0 to 30% cyclic components. Furthermore, the polybutadienes can optionally carry functional groups, e.g. B. hydroxyl groups, carboxyl groups etc.

Such polybutadienes with different configurations are known, e.g. B. "Macromolecules" by HG Elias, 4th edition, Hüthig and Wepf-Verlag, Basel, Heidelberg, New York, pages 676 and 744 to 746 and 1012 ff.

The monomers or oligomers a) to g) are generally incorporated into the graft copolymer in the same proportions as are used for the polymerization. The built-in units can essentially be statistically distributed. It is possible that component b) is not completely incorporated into the graft copolymer and is present as a residual monomer in the dissolved graft copolymer. It then either remains in the product as an additional solvent or can be removed by distillation together with solvent.

Suitable solvents for the production of component A) are, for. B. aliphatic, cycloaliphatic and / or aromatic hydrocarbons such as alkylbenzenes, e.g. B. Toluene, xylene; Esters such as ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, acetates with longer alcohol residues, butyl propionate, pentyl propionate, ethylene glycol monoethyl ether acetate, the corresponding methyl ether acetate; Ethers such as ethylene glycol acetate monomethyl, ethyl or butyl ether; Ketones such as methyl amyl ketone, methyl isobutyl ketone, glycols, alcohols, lactones or the like or mixtures of such solvents.

The graft copolymers A) can be prepared continuously or batchwise. Usually, the monomer mixture and the initiator are metered uniformly and continuously into a polymerization reactor and, at the same time, the corresponding amount of polymer is continuously removed. Chemically almost uniform copolymers can preferably be produced in this way. Copolymers which are almost chemically uniform can also be prepared by metering the monomer mixture and the initiator into the polymerization reactor at a constant rate without removing the polymer.

In general, the graft copolymerization takes place in the temperature range from 140 to 240 ° C., preferably 160 to 210 ° C., under a pressure of up to 25 bar. The initiators are used in amounts of 0.05 to 15% by weight, preferably 1 to 10% by weight, based on the total amount of components a) to g).

Suitable initiators for the preparation of the graft copolymers A) are conventional free-radical initiators based on azo or peroxide, but only those which have a sufficiently long half-life of about 5 seconds to about 120 minutes for the polymerization in the temperature range mentioned above. For example, 2,2'-azobis (2-methylpropannitrile), 2,2'-azobis (2-methylbutanenitrile), 1,1'-azobis (cydohexane carbonitrile), tert-butyl peroxy-2-ethylhexanoate, tert. -Butylperoxydiethylacetat, tert-butyl peroxyisobutyrate, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-tert-butylperoxycyclohexane, tert-butylperoxy-3,5,5-trimethylhexanoate , tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy acetate, tert-butyl peroxybenzoate, dicumyl peroxide, tert-butyl cumyl peroxide, Di-tert-butyl peroxide and di-tert-amyl peroxide.

The graft copolymers A) which are essential to the invention represent valuable binder components for high-solids two-component paints. In this context, "two-component paints" are understood to mean both "one-pot systems" and "two-pot systems". Since the polymer resins according to the invention are binder components for two-component lacquers, the lacquers contain a hardener component in addition to the polymer resins according to the invention (and optionally further polyhydroxyl compounds and / or amine reactive thinners). If this hardener is, for example, a polyisocyanate with free isocyanate groups, the ready-to-use coating compositions can only be produced by mixing the components shortly before they are processed. In such a case it would be a "two-pot system". However, if the hardener is a compound that only reacts with the polymer resins of the invention at elevated temperature, for example polyisocyanates with blocked isocyanate groups, the hardener can also be mixed with the polymer resin at room temperature to form a "one-pot system" that can be stored at room temperature. be united.

When the graft copolymers essential to the invention are used according to the invention, these are optionally used in a mixture with other organic polyhydroxyl compounds known from polyurethane coating technology as a polyhydroxyl component and / or in a mixture with amine reactive diluents. These other polyhydroxyl compounds can be the usual polyester, polyether, polycarbonate, polyurethane or polyacrylate polyols. As further organic polyhydroxyl compounds, if they are used in addition to the graft copolymers essential to the invention, the polyacrylate polyols and / or polyester polyols known per se are preferably used. The amine reactive diluents may be products with blocked amino groups, such as. As aldimines or ketimines, or those which still have free, but weakened in their reactivity, amino groups, such as. B. Aspartic acid ester, act. As a rule, the amine reactive thinners have more than one (blocked) amino group, so that they participate in the crosslinking reaction to build up the polymeric coating film network.

When the graft copolymers essential to the invention are used according to the invention, they can be used in admixture with up to 70, preferably up to 50% by weight of other polyols and / or amine reactive diluents of the type mentioned by way of example. However, the graft copolymers essential to the invention are particularly preferably used as the sole polyol component in the use according to the invention.

The hydroxyl group content of the graft copolymers A) is 0.53 to 8.76% by weight, preferably 0.88 to 8.03% by weight and particularly preferably 1.31 to 7.3% by weight.

As reaction component B) for the hydroxyl-containing graft copolymer resins A) for the preparation of the binder combinations according to the invention for coatings and coatings, crosslinking reagents are suitable which, through chemical reactions with the hydroxyl groups of the graft copolymer resins, lead to curing of the coatings according to the invention, such as aminoplast resins, e.g. B. corresponding melamine derivatives, such as alkoxylated melamine resins or mdamine-formaldehyde condensate products (for example FR-A 943 411, "The Chemistry of Organic Filmformers", pages 235-240, John Wiley &amp; Sons, Inc., New York, 1974) and customary ones Crosslinking agents, e.g. B. with alcoholic hydroxyl groups reactive epoxides, carboxylic acid anhydrides, phenolic resins, resol resins, urea resins or guanidine resins or mixtures thereof.

Preferred reaction components B) for the graft copolymers A) which are essential for the invention for the preparation of the binder combinations according to the invention for coatings and coatings are commercially available, optionally blocked, coating polyisocyanates, ie above all the known urethane groups, uretdione groups, allophanate groups and in particular biuret groups or isocyanurate groups, modification products of simple diisocyanates such as B. 1,6-diisocyanatohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 1-methyl-2,4-diisocyanatocyclohexane and its mixtures with up to 35% by weight, based on the total mixture, on 1-methyl-2,6-diisocyanatocyclohexane; 2,4-diisocyanatotoluene and its mixtures with up to 35% by weight, based on the total mixture, of 2,6-diisocyanatotoluene or mixtures thereof. The corresponding "lacquer polyisocyanates" with aliphatic and / or cycloaliphatic free isocyanate groups are particularly preferably used. Suitable blocking agents for blocked polyisocyanates which may be used are e.g. B. ε-caprolactam, butanone oxime, phenol or phenol derivatives, secondary amines, optionally as part of a heterocyclic ring system, alkyl malonate, etc.

The "lacquer polyisocyanates" containing urethane groups include e.g. B. the reaction products of 2,4- and optionally 2,6-diisocyanatotoluene or 1-methyl-2,4- and optionally 1-methyl-2,6-diisocyanatocyclohexane with insufficient amounts of trimethylolpropane, or its mixtures with simple diols, such as B. the isomeric propane or butanediols. The preparation of such lacquer polyisocyanates containing urethane groups in a practically monomer-free form is described, for example, in DE-PS 1 090 196.

The biuret group-containing lacquer polyisocyanates which are particularly preferred in the use according to the invention include, in particular, those based on 1,6-diisocyanatohexane, the preparation of which is described, for example, in EP-A 3 505, DE-A 1 101 394, US Pat. No. 3,358 010 or US-A 3,903,127.

The likewise particularly preferred lacquer polyisocyanates containing isocyanurate groups include, in particular, the trimerizates or mixed trimerizates of the diisocyanates mentioned above by way of example, such as. B. the isocyanurate group-containing polyisocyanates based on diisocyanatotoluene according to GB-A 1 060 430, GB-A 1 506 373 or GB-A 1 485 564, the mixed trimer of diisocyanatotoluene with 1,6-diisocyanatohexane, for example according to DE-A 1 644 809 or DE-A 3 144 672 are accessible and in particular the aliphatic or the aliphatic-cycloaliphatic trimer or Mixed trimers based on 1,6-diisocyanatohexane and / or isophorone diisocyanate, for example those described in US Pat. No. 4,324,879, US Pat. No. 4,288,586, DE-A 3 100 262, DE-A 3 100 263, DE-A 3 033 860 or DE-A 3 144 672 are available. The lacquer polyisocyanates used in the use according to the invention generally have an isocyanate content of 5 to 25% by weight, an average NCO functionality of 2.0 to 5.0, preferably 2.8 to 4.0 and a residual content, monomeric diisocyanates used for their preparation of less than 2% by weight, preferably less than 0.5% by weight. Of course, any mixtures of the paint polyisocyanates mentioned by way of example can also be used.

In the high-solids two-component polyurethane lacquers used in the use according to the invention, the polyol component and the polyisocyanate component are in an equivalent ratio of isocyanate groups to hydroxyl groups of 5: 1 to 1: 2, preferably 1.5: 1 to 1: 1.2, corresponding amount in front. The two-component binders obtained by mixing the two components have a limited processing time of approx. 4th up to 24 hours and are processed either as such (solvent-based clearcoats), but preferably with the usual auxiliaries and additives. These auxiliary agents and additives, which may be used, can either be added to the mixture or to the individual components before they are mixed.

Examples of auxiliaries and additives are other solvents, such as, for example, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, n-hexyl acetate, n-heptylacetate, 2-ethylhexyl acetate, methoxypropyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, and higher Aromatic mixtures, white spirit or any mixtures of these solvents.

Other auxiliaries and additives that may be used are e.g. B. plasticizers, such as tricresyl phosphate, phthalic diesters, chlorinated paraffins; Pigments and fillers, such as titanium dioxide, barium sulfate, chalk, carbon black; Catalysts such. B. N, N-dimethylbenzylamine, N-methylmorpholine, zinc octoate, tin II octoate or dibutyltin dilaurate; Leveling agent; Thickeners; optionally stabilizers, such as substituted phenols; organofunctional silanes as adhesion promoters as well as light stabilizers and UV absorbers. Such light stabilizers are, for example, sterically hindered amines, as described in DE-A 2 417 353 (= US-A 4 123 418 and US-A 4 110 304) and DE-A 2 456 864 (= US-A 3 993 655 and US -A 4 221 701). Particularly preferred compounds are: bis- (1,2,2,6,6-pentamethylpipendyl-4) sebacate, bis- (2,2,6,6-tetramethylpipendyl-4) sebacate, n-butyl- (3, 5-di-tert-butyl-4-hydroxybenzyl) malonic acid bis (1,2,2,6,6-pentamethylpiperidyl-4) ester.

The moisture adhering to the fillers and pigments can be dried by prior drying or by the use of water-absorbing substances such as. B. molecular sieve zeolites are removed.

The drying of the lacquer films resulting from the use according to the invention can be carried out using blocking agent-free polyisocyanates as crosslinking agents at room temperature and does not require an increase in temperature in order to achieve the optimal properties mentioned at the outset. When using the binders as a repair varnish, however, a temperature increase to approx. 60 to 100 ° C, preferably 60 to 80 ° C, recommended for a period of 20 to 60 minutes to shorten the drying and curing time.

When using blocked polyisocyanates or the other product groups mentioned above as crosslinking agents, higher temperatures of, for example, 100 to 240 ° C., preferably 120 to 220 ° C., must be used for drying or curing the paint films.

The resulting paint films are characterized by high hardness, good elasticity, excellent weather and chemical resistance as well as a high gloss. The curing times for both the physical drying and the chemical crosslinking are very short, so that appropriately coated commodities are very quickly resistant to solvents and chemicals and can be used.

The paints according to the invention are therefore particularly suitable for painting large vehicles, such as. B. aircraft, railway and tram wagons, truck bodies, etc. Another preferred area of ​​application is their use as automotive refinish. The coatings are also suitable for corrosion protection applications, such as the coating of bridges and electricity pylons, for wood and furniture painting and for automotive painting and industrial applications.

The lacquers according to the invention are applied by customary methods, for example by spraying, pouring, dipping, brushing, spraying or rolling. The paints according to the invention are suitable both for the production of primers and for the production of intermediate layers and in particular for the production of top layers on the substrates to be coated.

<b>Examples</b>

Unless otherwise stated, all percentages relate to the weight. 1. General manufacturing instructions for the graft copolymers A1 to A8 essential to the invention and the comparative products V1 and V2 Part I is placed in a 5 l stainless steel pressure reactor with stirrer, distillation device, storage tank for monomer mixture and initiator including metering pumps and automatic temperature control and heated to the desired polymerization temperature (190 ° C in the examples). Then part II (monomer mixture) is metered in in 1.5 hours and part III (initiator) in 1.75 hours, starting with separate feeds, the polymerization temperature being kept almost constant (± 2 ° C.). The mixture is then stirred at the polymerization temperature for 30 minutes. The mixture is then cooled to room temperature and the solids content is determined. The graft copolymers should have a solids content of 75 ± 1%, with some of the α-olefin used not being incorporated into the polymer. If the solids content is ≤ 73%, 5% of the original amount of initiator is reactivated at 150 ° C for 30 minutes. With a fixed content between 73 and 74%, distillation is carried out to 75 ± 1%. The graft copolymer is then filtered through a filter (Seitz Supra 5500). The compositions of parts I to III and the characteristics of the products obtained are listed in Table I. 2. Adjustment of copolymer 2 of EP-A 638 591 as comparative example V3 The copolymer 2 of EP-A 638 591 was reproduced exactly in accordance with the preparation instructions and the composition. A product with the following characteristics was obtained:<dl id="dl0001" compact="compact"><dt>Fixed salary:</dt><dd>74,2 %</dd><dt>Viscosity at 23 ° C:</dt><dd>8450 mPa.s</dd><dt>Acid number, Lff / FH:</dt><dd>7.5 / 10.1 mg KOH / g</dd><dt>Hydroxyl number, Lff / FH:</dt><dd>109/147 mg KOH / g</dd><dt>Hazen color number:</dt><dd>65 APHA</dd></dl><img file="EP0778298A2_D0004.tif" />3. Example of use This example describes the production of ready-to-use paints based on the polyacrylate polyols A1 to A8 and V1 to V3, their application and the testing of the resulting paint films. Clear coatings were produced to assess the general paint properties. For this purpose, the polyols A1 to A8 and V1 to V3 were mixed with a lacquer polyisocyanate, an NCO / OH ratio of about 1: 1 being maintained. ®Desmodur N 3390, an isocyanurate group-containing polyisocyanate based on 1,6-diisocyanatohexane, 90% dissolved in butyl acetate / solvent naphtha 100 (1: 1) was used as the coating polyisocyanate; NCO content of the solution: approx. 19.4% by weight, content of free 1,6-diisocyanatohexane in the solution: less than 0.5%. Based on solid resin (sum of the solid proportions of polyol and polyisocyanate), the following proportions of additives were used.<tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Components</entry><entry namest="col2" nameend="col2" align="center">% By weight on solid</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Dabco 33 LV (PUR catalyst from Air Products, 10% in butyl acetate</entry><entry namest="col2" nameend="col2" align="char" char=",">0,3</entry></row><row><entry namest="col1" nameend="col1" align="left">BYK 331 (leveling agent from BYK-Chemie, 50% in butyl acetate)</entry><entry namest="col2" nameend="col2" align="char" char=",">0,3</entry></row><row><entry namest="col1" nameend="col1" align="left">Tinuvin 1130 (UV absorber from Ciba-Geigy, Basel, 50% in xylene</entry><entry namest="col2" nameend="col2" align="char" char=",">2,0</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Tinuvin 292 (light stabilizer from Ciba-Geigy, Basel, 50% in xylene</entry><entry namest="col2" nameend="col2" align="char" char=",">1,0</entry></row></tbody></tgroup></table></tables>

A mixture of methoxypropyl acetate, xylene and n-butyl acetate (1: 1: 1) was used as the solvent. The salary was:<ul id="ul0005" list-style="none" compact="compact"><li>approx. 56% by weight of binder,</li><li>approx. 2% by weight of additives,</li><li>approx. 42% by weight of solvent</li></ul>

The run-down time (DIN 53 211, 4 mm nozzle) was approx. 20 s. The paints are now ready for spraying and now have a VOC (volatile organic compounds) of 3.5 lbs / gal.

The lacquers were applied to glass plates, dried both at room temperature and at 60 ° C. for 30 minutes, the drying rate (DIN 53 150) being determined and then stored at room temperature for 7 days. The dry film thickness was approximately 40 to 50 µm.

The König hardness (DIN 53 157), the Gardner gloss at a 60 ° angle (DIN 67 530) and the solubility by super gasoline (after 1, 2, 3 and 4 days of storage at room temperature) were then tested. The Erichsen indentation was determined on appropriately coated test panels.

In addition, the yellowing resistance when irradiated with short-wave UV light was tested in the QUV test (QUV-Accelerated Weathering Tester, ASTM G 53-77). For this purpose, clear lacquers based on the polyols A 1 to A 8 and V1 to V3 were applied to aluminum sheets (68 mm x 150 mm) which had been primed and coated with a white basecoat. After application and drying of the paints (30 minutes at 60 ° C), they were stored for 7 days at room temperature and then in the QUV device (Fa. Q-Panel Company) checked. The cycle was irradiated for 4 hours in intensive, unfiltered UV light in the wavelength range from approx. 280 to 370 nm (maximum at 313 nm) or left in the dark for 4 hours with a total duration of 1,000 hours. After the sample was washed off, the total color difference DE (compared to the non-weathered plate) was determined using a color measuring device as a measure of the yellowing that had occurred.

The test results for paints based on copolymers A1 to A8 and V1 to V3 are shown in Table 2.<tables id="tabl0002" num="0002"><img file="EP0778298A2_D0005.tif" /></tables>

Discussion of the results

2K PUR clear coats based on polyols A1 to A8 dry quickly at room temperature despite their high solids content and are resistant to the effects of premium petrol after only 1 to 2 days. Gloss, elasticity and film hardness are at a high level, comparable to today's standard systems. In contrast, the varnishes of polyols V1 and V2, which fall under the claim of EP 225 809 and do not contain polybutadiene, have a longer drying time and a somewhat poorer resistance to super petrol. The lacquer film of the polyol V3 does dry quickly, but after one day it has poor super gasoline resistance, which improves after 2 and 3 days and is only in order after 4 days. The test results thus clearly show that high-solids 2-component PUR clearcoats based on the polyols A1 to A8 according to the invention, despite their high-solids character, have both very fast drying and very good petrol resistance, and that coated objects, preferably motor vehicles, do can be brought to their intended use after a very short time.