MXPA96001708A - Powder lacquer for ma coatings - Google Patents

Abstract

The present invention relates to a powder coating composition for the production of matt coatings, characterized in that it comprises: A) a hydroxyl group-containing component which is solid below 40 ° C, and liquid above 130 ° C. and has an OH number of 25 to 200 and an average molecular weight of 400 to 10,000 B) a compound for addition polymerization which estábasado in aliphatic and / oo cycloaliphatic polyisocyanate containing uretdione groups and isocyanate groups optionally free, and is solid below 40 ° C and liquid above 125 ° C, C) a component containing carboxyl groups and / or carboxylic acid anhydride, which is solid below 40 ° C and liquid above 160 §C, and is selected from C1) aliphatic dicarboxylic acids and / or cycloaliphatic containing from 4 to carbon 20átomos, C2) monomeric anhydrides and / or polymeric losácidos C1), which may be optionally m odificados with polyols or polyisocyanates and C3) aliphatic hydroxycarboxylic acids containing 4 to 18átomos carbon, and D) a component containing groups which are reactive with the carboxyl and / or acid s odium carboxylic anhydride, and which has an average molecular weight weight from 250 to 1000, with the proviso that components A), B), C) and D) are present in quantities such that i) 0.6 to 1.4 isocyanate groups of component B) are present for each hydroxyl group of the component A), ii) 0.3 to 1.5 groups of component D) which are reactive with carboxyl groups and / or carboxylic acid anhydride are present for each carboxyl equivalent of component C) and iii) the amount of components C) and D) are from 10 to 40% by weight, based on the total weight of components A), B), C) and

Description

POWDER MATT FOR MATT COATINGS FIELD OF THE INVENTION The invention relates to a powder coating for the production of matt coatings. BACKGROUND OF THE INVENTION The development of powder lacquers together with high solids lacquers and aqueous coating systems gain increasing significance. The powder lacquers do not give off any solvent when applied and can be processed with very high material utilization. With heat-curable powder coatings based on polyurethane, particularly valuable coatings can be obtained, resistant to light and to the action of the weather. Most known polyurethane powder coatings (PUR) are composed of solid polyester polyols which are hardened with aliphatic or cycloaliphatic blocked polyisocyanates, solids. For various applications, for example for the coating of office furniture, electrical and electronic equipment or for purely decorative coatings, there is a great interest in powder coatings that on maturing give rise to matt surfaces. Also for the covering of elements of facades are often undesirable systems of glossy, strongly reflective lacquers. Therefore, there have been trials to develop matt powder lacquers, based on PUR. The use of mineral matting agents or finely divided polymers, a method usable in wet lacquers for the adjustment of small gloss graduations, in powder coating systems does not generally lead to the desired results; coatings with increasing contents in matting agent are losing in mechanical properties. Also, the "dry" mixture of two powder coatings of separately obtained binders of different bases, formulated equally in terms of coloring tonality, described in DE-A 2 147 653 and 247 779, gives unsatisfactory results. Especially when the supercoated lacquers produced have to be recycled, the matting effects obtained in this way are hardly reproducible. Polyurethane powder coatings of polyester polyols are known in combination with polyisocyanates based on isophorone diisocyanate (IPDI), blocked by pyromellitic dianhydride and e-caprolactam as crosslinking component, which harden to give matt coatings (DE-A 3 238 129, for example ). Matte coatings of powders are also obtained by crosslinking hydroxylated polyesters with special derivatives of trans-1,4-diisocyanatocyclohexane, blocked by e-caprolactam, with a melting range above 140 ° C. (DE-A 37 11 374, for example) or polyisocyanates containing urea groups blocked by e-caprolactam (DE-A 37 39 479, for example), which can be obtained by transformation of partially blocked diisocyanates with di- or polyanes. The use of special blocked polyisocyanate combinations exhibiting carboxyl groups and crosslinking agents of polyepoxides, for example triglycidyl isocyanurate (TGIC), as hardener component for hydroxyl-functional powdered binders is known, for example, from DE-A 32 32 463. These "3-component" powder coating systems produce highly stable, weather-resistant coatings after baking, with adjustable, reproducible matting effects. Although these PUR powder coatings harden to provide matte surfaces, however, the basic disadvantage of containing blocked polyisocyanates as crosslinking components is that, in the baking process, they release the blocking agent in the form of the so-called leaving group, which is released to the environment. Therefore, its handling is expensive (for example, air purification, recycling). An assay for discarding these blocked polyisocyanate crosslinkers disadvantageous in principle is to be considered in the use of linear IPDI powder coat hardeners containing uretdione groups free of blocking agents (EP-A 639 598)., for example), in which the crosslinking is carried out by thermal reopening of the uretdione groups. The use of such extruded group urethane-free powder coat hardeners for the production of matt coatings was also tested. DE-A 33 28 133 describes polyaddition compounds based on an IPDI uretdione with melting points above 130 ° C. which, in combination with polyester polyols, are cured to give matt coatings. In any case, uretdione crosslinkers for powder coatings with such high melting points are hardly available. Since a clear reopening of the uretdione ring is already established at temperatures from a few loops, such products can only be obtained in expensive solution processes with a subsequent evaporation step. Also in the finished powder lacquer formulation in which the two polyol and hardening reaction components are mixed, by extrusion in the molten state generally, a temperature of 80 to lyole should not be exceeded to prevent premature crosslinking. However, under such conditions of melt extrusion, a completely homogeneous incorporation of the crosslinker of particularly high melting point into the binder component is not possible. The matting effect here achievable must be attributed to the insufficient intermixing of the two reaction components. Due to the heterogeneities present in the lacquer powder, the coatings obtained exhibit only unsatisfactory surface properties. EP-A 553 750 discloses powder coatings of a mixture of two hydroxylated polyesters of different OH and reactivity ratios and crosslinking agents for IPDI based uredode powder coatings, free of leaving group, for the production of coatings mate. However, this process is restricted to the use of very special polyester polyols. Therefore, the technical problem of the invention was to develop new powder lacquers of PUR free of leaving group that harden to give coatings resistant to solvents and chemical agents, with adjustable, reproducible low brightness graduations. This problem could be solved with the set-up of the powder lacquers according to the invention. The powder lacquers according to the invention rest on the surprising observation that polyurethane powder lacquers composed of a polyester polyol and a powder coating crosslinker containing uretdione groups, which are baked to generally give high gloss lacquered films, provide coatings completely matte by adding to the formulation, in addition, a combination of a crosslinking agent exhibiting carboxyl and / or carboxylic acid anhydride and other crosslinker component exhibiting groups reactive towards carboxyl and / or carboxylic acid anhydride and homogenizing all the components by extrusion in the molten state. This was surprising, since the powdered lacquer composed of polyester polyol, urethodione hardener only another, for example only a crosslinking component exhibiting carboxyl and / or carboxylic acid anhydride or only a crosslinking component exhibiting reactive groups against carboxyl and / or carboxylic acid anhydride, give highly bright coatings, and also the combination of a component that exhibits carboxyl and / or carboxylic acid anhydride and another that exhibits groups reactive towards carboxyl and / or carboxylic acid anhydride alone throws a brilliant movie. Therefore, it was not to be expected in any way that the powder coatings according to the invention were hardened to give matt surfaces, especially since it is known that the addition of a binder combination for high molecular weight powder coatings is known. which exhibits carboxyl groups and a reactive component against this binder, for example of a polyepoxide crosslinker, to a powder coating made of polyurethane also produces a coating material that hardens with gloss. In spite of the disadvantages described above, it is quite usual in practice to obtain matt powder coating agents by the process described in DE-A 2 147 653 and 2 247 779 by dry mixing. "and subsequent co-grinding of two powder coatings formulated separately from different chemical basis and reactivity, for example from a powder lacquer of polyurethane and a second powder lacquer composed, for example, of a carboxylated polyester and a crosslinking agent of polyepoxide, but the homogenizatof the two reactive systems by extrusof the melt always throws high-gloss powder coatings. DESCRIPTOF THE INVENTThe object of the inventis a powder coating for the productof matt coatings, which contains: A) A component binder that exhibits hydroxyl groups, present in solid form below 02C and in liquid form above 1302C, with an OH number of 25 to 200 and a pe medium molecular weight (calculated from the functlity and the hydroxyl content) 'from 400 to 10,000. B) A polyadditcompound exhibiting uretd groups and, optlly, free isocyanate, present in solid form below 402C and in liquid form above 1252C, based on aliphatic and / or cycloaliphatic diisocyanates. C) A component exhibiting carboxyl and / or carboxylic acid anhydride groups, present in solid form below 40 = 0 and in liquid form above 1602C, composed of at least one component selected from Cl) Dicarboxylic acids aliphatic and / or cycloaliphatic with 4 to 20 carbon atoms, C2) Monomers and / or polymers, optlly modified, of such dicarboxylic acids and C3) Aliphatic hydroxycarboxylic acids with 4 to 18 carbon atoms, D) A component which exhibits groups reactive towards carboxyl groups and / or carboxylic acid anhydride of an average molecular weight of 200 to 5,000, and, if appropriate, E) Adjuvants and additives known from the powder coating technology, with the proviso that that components A), B), C) and D) must be present in proport such that each hydroxyl group of component A) corresponds to 0.6 to 1.4 isocyanate groups of component B), understood as isocyanate groups of component B) the sum of isocyanate groups present in the form of a dimer, such as uretd groups and free isocyanate groups, correspond to 0.3 to 1.5 reactive groups to each carboxyl equivalent of component C). carboxyl and / or carboxylic acid anhydride of component D), one carboxyl group corresponding to one and one anhydride group of carboxylic acid to two carboxyl equivalents, and the proportof components C) and D) amounting to 10 to 40% by weight of the total amount of components A), B), C) and D). It is also an object of the inventto use this powder coating for the coating of heat-resistant substrates. Component A) contained in the powder lacquers according to the inventare any binders exhibiting hydroxyl groups, known in the powder coating technology, with a hydroxyl number of 25 to 200, preferably 30 to 150. , of an average molecular weight (calculated from functlity and hydroxyl content) of from 400 to 10,000, preferably from 1,000 to 5,000, which are solids below 02C and liquids above 130ac. Such binders are, for example, polyesters, polyacrylates or polyurethanes containing hydroxyl groups, for example those described as binders for powder coatings in EP-A 45 988 and 254 152, but also any mixtures of such resins. Component A) is preferably polyesters containing hydroxyl groups whose softening temperature - determined by differential differential analysis (TAD) - is within the temperature range of 40 to 120 ° C, particularly preferably within the temperature range of 45 to 1102C. Component B) contained in the powder lacquers according to the invention is polyaddition compounds which contain uretdione groups and, optionally, free isocyanates, based on aliphatic and / or cycloaliphatic diisocyanates, especially those based on 1,6-hexamethylene diisocyanate (HDI), l-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 4,4'-diisocyanato-dichlohexylmethane or of any mixtures of these diisocyanates. Polyaddition compounds which exhibit uretdione groups and, optionally, free isocyanates which are taken into consideration as component B) generally exhibit a content of uretdione groups (calculated as C2N202, molecular weight = 84) from 3 to 17 % in weigh. The melting point or melting range of these compounds is generally within the temperature range of 40 to 125SC. The production of such polyaddition compounds by transformation of polyisocyanates which exhibit uretdione groups with bifunctional and, optionally, optional compounds which are reactive towards isocyanate groups, in particular divalent and, if appropriate, monovalent alcohols, is known in principle (for example, DE-A 2 420 475, EP-A 45 996, 45 998).

Polyaddition compounds which exhibit especially preferred uretdione groups as component B) are those which exhibit: a content of free isocyanate groups (calculated as NCO, molecular weight = 42) of 0 to 2% by weight, a content of uretdione groups (calculated as C2N2? 2, molecular weight = 84) from 3 to 16% by weight, a content of urethane groups (calculated as CHN02, molecular weight = 59) of 10 to 22% by weight, a content of carboxylic acid ester groups (calculated as C0 ?; molecular weight = 44) from 0 to 20% by weight, and / or a carbonate group content (calculated as C03, molecular weight = 60) from 0 to 25% by weight, with the proviso that the content in ester groups of carboxylic acid and carbonate groups amounts to at least 1% by weight. The preparation of such polyaddition compounds which exhibit uretdione groups takes place, for example, according to EP-A 639 598, by transformation of I) polyisocyanates exhibiting uretdione groups of an average isocyanate functionality of 2.0, optionally with the coemployment of II) other diisocyanates in a proportion of up to 70% by weight, based on the total weight of components I) and II), with III) diols exhibiting ester and / or carbonate groups of an average molecular weight of 134 to 1200, optionally with the simultaneous coefficient of IV) free diols of free ester and / or carbonate groups with a molecular weight between 62 and 300, in a proportion of up to 80% by weight, based on the total weight of components III) and IV), and / or optionally V) other monofunctional compounds reactive towards isocyanate, in a proportion of up to 40% by weight, based on the total weight of components III), IV) and V), with observance of a ratio of equivalents of isocyanate groups to groups reactive towards isocyanate of 1.2: 1 to 0.6: 1. Component B) is used in the powder coating according to the invention in a proportion such that each hydroxyl group of the binder component A) corresponds to 0.6 to 1.4 isocyanate groups of component B), preferably 0, 8 to 1.2, the isocyanate groups of component B being understood as the sum of the isocyanate groups present in the form of a dimer, such as uretdione groups and free isocyanate groups. In the component C) contained in the powder coating materials according to the invention are components exhibiting carboxyl and / or carboxylic acid anhydride, composed of at least one component selected from Cl) aliphatic dicarboxylic acids and / or cycloaliphatics with 4 to 20 carbon atoms, C2) monomers and / or polymers, optionally modified, of such dicarboxylic acids and C3) aliphatic hydroxycarboxylic acids with 4 to 18 carbon atoms, are suitable dicarboxylic acids Cl), for example , succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid (1, 10-decanedicarboxylic acid) or hexahydrophthalic acid. Suitable C2) components are, for example, monomeric anhydrides of such dicarboxylic acids, such as succinic anhydride, glutaric anhydride or hexahydrophthalic anhydride, or polymeric anhydrides of such dicarboxylic acids as those obtainable by intermolecular condensation of the aforementioned acids or mixtures thereof. . Specific examples are (poly) adipic anhydride, (poly) azelaic anhydride, (poly) sebacic anhydride or (poly) dodecanedioic anhydride. The molecular weight Mw of these polyanhydrides determined by gel filtration chromatography using polystyrene as a standard is, in general, between 1,000 and 5,000. The polyanhydrides are prepared, for example, by reacting the dicarboxylic acids or the mixture of dicarboxylic acids with acetic anhydride at temperatures of 120 to 2002 C, preferably 120 to 170 ° C. The acetic acid formed therewith is removed by vacuum distillation, for example. Also suitable are C2) components, modified anhydrides of the dicarboxylic acids mentioned in Cl), for example polyanhydrides modified by polyols, such as those obtainable according to EP-A 299 420. In these polyanhydrides modified by polyols, the molar ratio of anhydride groups to carboxyl groups is, in general, 0.04: 1 to 5. : 1, preferably in 1: 1 to 3: 1. Also suitable are polyisocyanate-modified polyanhydride components C), such as those obtainable according to DE-A 4 427 225 by conversion of dicarboxylic acids and / or (poly) dicarboxylic anhydrides with any organic polyisocyanates and, optionally, other compounds which exhibit reactive amino and / or hydroxyl groups to anhydride groups. Such (poly) dicarboxylic anhydrides modified by polyisocyanates generally exhibit a carboxyl group content (calculated as C02H).; molecular weight = 45) of 0.5 to 30% by weight, a content of carboxylic acid anhydride groups (calculated as C20, molecular weight = 72) of 5 to 35% by weight and a nitrogen content, present in amido and / or urea groups, from 0.2 to 8% by weight. Suitable C3) hydroxycarboxylic acids are, in particular, those which exhibit a melting point which is between 40 and 150 ° C. These include, for example, 2-hydroxy-isobutyric acid (812C), 2-hydroxyhexanoic acid (612C), 10-hydroxydecanoic acid (768C), 12-hydroxydodecanoic acid (862C), 16-hydroxyhexadecanoic acid (982C) and 12-hydroxyoctadecanoic (80SC). These hydroxycarboxylic acids are generally used only in combination with C2) polyanhydrides, preferably not modified, in proportions of up to 50% by weight, based on the weight of the polyanhydride. With particular preference, component C) consists exclusively of at least one aliphatic dicarboxylic acid saturated with 4 to 12 carbon atoms, a monomeric anhydride or polymer of such dicarboxylic acids or of a polyanhydride of such dicarboxylic acids modified by aliphatic polyisocyanates and / or cycloaliphatics. The component D) contained in the powder coating materials according to the invention is composed of compounds which exhibit groups reactive with carboxyl and / or carboxylic acid anhydride groups, having an average molecular weight of 200 to 5,000, preferably 200 to 2,000. , particularly preferably from 250 to 1,000, such as those generally used in powder coating technology as crosslinking components for powder coating binders containing carboxyl groups. Suitable components D) are, for example, the known polyepoxides, such as triglycidyl isocyanurate (TGIC) and triglycidurazole or their oligomers, glycidyl ethers, for example those based on bisphenol A, but also glycidyl esters, such as, for example, italic acid. tetrahydro- and hexahydrophthalic or any mixtures of such polyepoxides. Suitable components D) are also, for example, compounds that exhibit β-hydroxyalkylamido groups, such as those described in EP-A 322 834 as crosslinking components for polyesters containing carboxyl groups. The preparation of such β-hydroxyalkyl amides is generally carried out by base catalyzed transformation of esters of organic polycarboxylic acids with β-hydroxyalkylamines at temperatures of up to 200 ° C., with simultaneous separation by distillation of the alcohol which thereby originates. As component D), preferably in the powder coating materials according to the invention, TGIC and / or its oligomers or β-hydroxyalkylamides based on esters of dicarboxylic acids saturated with 4 to 12 carbon atoms in the dicarboxylic acid part are used. With particular preference, component D) consists of a β-hydroxyalkylamide, such as that obtained by transformation of diethanolamine with a mixture of 9 parts by weight of dimethyl adipate and 1 part by weight of dimethyl glutarate. Component D) is used in the powder coating according to the invention in proportions such that each carboxyl equivalent of component C) corresponds to 0.3 to 1.5 groups of component D) reactive towards carboxyl groups and / or carboxylic acid anhydride, preferably from 0.4 to 1.2, one carboxyl group corresponding to one equivalent and one carboxylic acid anhydride group to two equivalents of carboxyl. The proportion of components C) and D) in the total amount of components A), B), C) and D) in the powder coating materials according to the invention is from 10 to 40% by weight, preferably from 15 to 40% by weight. 35% by weight. If appropriate, the powder coating material according to the invention can also contain the conventional adjuvants and additives E) known from the powder coating technology. This concerns, for example, catalysts such as, for example, tin hexanoate (II), tin octanoate (II), tin laurate (II), dibutyltin oxide, dibutyltin chloride, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin alloate, dioctyltin diacetate, 1,4-diazabicyclo [2.2.2] octane, 1,5-diazabicyclo [ 4.3.0] non-Seno or i, 8-diazabicyclo [5.4.0] undec-7-ene. If necessary, mixtures of catalysts are also used. Other representatives of suitable catalysts as well as details on the mode of activity of such catalysts are described, for example, in Kunststoffhandbuch (Handbook of plastics) volume VII, edited by Vieweg and Höchtlen, Carl-Hanser-Verlag, München 1966, pages 96 a 102. The catalysts as additive E) are used, in general, in proportions of 0.1 to 5% by weight, preferably 0.1 to 3% by weight, based on the sum of components A), B), C) and D). Further excipients and additives E) are also, for example, leveling agents, such as, for example, butyl polyacrylate or those based on polysilicones, photoprotective agents such as, for example, sterically hindered amines, UV absorbers, such as, for example, benzotriazoles or benzophenones and pigments such as, for example, titanium dioxide. The additives E) which are frequently used together with other auxiliary agents and additives are also, in particular, color stabilizers against the danger of yellowing of over-baking. Especially suitable are trialkyl and triaryl phosphites, which optionally have inert substituents, such as, for example, triethyl phosphite, triphenyl phosphite or, preferably, trisalkylphenyl phosphite, the alkyl substituents having 6 to 12 carbon atoms. Most preferred is trisnonylphenyl phosphite (technical product, essentially composed of an ester of the phosphorous acid with the addition product of tripropylene to the phenol). To obtain the finished powder coating material, the components A), B), C), D) and, if appropriate, E) are mixed intimately with one another and then combined in the molten state with a homogeneous material. This can be carried out in suitable assemblies, for example kneaders suitable for heating but, preferably, by extrusion in the molten state, the extrusion temperature being generally chosen in such a way that a maximum shear stress is exerted on the mixture. In order to avoid premature crosslinking of the powder coating material, an upper limit of the lye temperature should never be exceeded. The succession of the individual components A) to E) in the combination can be chosen in this procedure with wide freedom. A preferred form, in the sense of the invention, for the production of a finished powder coating material is, for example, intimately mixing in a first stage only two of the individual components, for example only components B) and C), in molten state, preferably immediately after obtaining one of components B) or C) and adding to the resulting homogeneous, storage stable material, composed of components B) and C), only at a later time, in a second stage , the rest of the components and extrude them together. Independently of the chosen method, the proportions of the individual components A), B), C) and D) are otherwise chosen, as already indicated above, in such a way that each hydroxyl group of the binder component A) 0.6 to 1.4 isocyanate groups of component B), preferably from 0.8 to 1.2, are understood as isocyanate groups of component B) the sum of the isocyanate groups present in the form of dimer as uretdione groups and of the free isocyanate groups and corresponding to each carboxyl equivalent of component C) from 0.3 to 1.5 groups of component D) reactive towards carboxyl and / or carboxylic acid anhydride, preferably from 0.4 to 1, 2, one carboxyl group to one and one carboxylic acid anhydride group to two carboxyl equivalents. The hydroxyl groups contained additionally, if necessary, in components C) and / or D) are not taken into consideration for the choice of the proportions of the individual components. The so-called NCO / OH equivalent ratio refers exclusively to the quantitative relation of component A) to component B). The extruded mass, after cooling to room temperature and after a suitable size reduction, is milled to obtain a powder coating and by sieving the granular components above the desired particle size are eliminated, for example, above 0 , 1 mm. The powder lacquer formulations thus obtained can be applied to the substrate to be coated by the usual powder application methods, such as, for example, powder electrostatic spraying or fluidized sintering. The coating is hardened by heating at temperatures of 110 to 220 μs, preferably 130 to 2002 ° C, for a period of time of, for example, about 10 to 30 minutes. Fully matte, hard and elastic coatings are obtained which are distinguished by outstanding leveling as well as good resistance to solvents and chemical agents. Any heat-resistant substrates (eg glass, metals, plastics) can be coated according to the invention. Examples All data in% are% by weight.

Obtaining the starting components Polyaddition Compound Ba) containing uretdione groups a) Obtaining a diol that exhibits ester groups: 901 g of 1,4-butanediol and 1,712 g of ethanol are mixed at room temperature under a nitrogen atmosphere. Caprolactone is contacted with 0.3 g of tin octoate (II) and then heated to 160 ° C. for 5 hours. After cooling to room temperature, a liquid, colorless product is obtained with the following properties: ti (23dC): 180 mPa-s OH number: 416 mg KOH / g Free caprolactone: 0.2% Average molecular weight (cale, from the OH count): 269 Content in ester groups (cale): 25.3% b) Obtaining component Ba) that exhibits ester and uretdione groups: They are heated to 80SC under a dry nitrogen atmosphere, 1,000 g (4.3 eq.) Of a polyisocyanate based of isocyanate-3, 3, 5-trimethyl-5-isocyanatomethyl-cyclohexane (IPDI) containing uretdione groups, with a content of free isocyanate groups of 17.9% and a content of uretdione groups (determined by hot titration ) of 19.1%. A mixture of 457 g (3.4 eq.) Of the diol which exhibits ester groups of a) and 117 g (0.9 eq.) Of 2-ethyl-l- is added in the interval of 30 minutes. Hexanol and stirred at a reaction temperature of at most 10, until the NCO content of the reaction mixture after about 2 hours has already fallen to a value of 0.7%. The melt is poured onto a sheet for cooling and a practically colorless solid resin is obtained with the following properties: NCO content: 0.7% Content of uretdione groups (cale): 12.1% Total NCO content (cale) : 12.8% Melting point: 82 to 83ac Polyaddition compound Bb) containing uretdione groups 1,000 g (4.3 eq.) Of the polyisocyanate containing uretdione groups used to obtain component Ba) are placed in 1.270 g of water-free toluene, at 80 ° C under a dry nitrogen atmosphere. A mixture of 153 g (3.4 eq.) Of 1,4-butanediol and 117 g (0.9 eq.) Of 2-ethyl-1-hexanol is added over the 30 minute interval and stirred at a temperature reaction temperature of 1002C until the NCO content has decreased to a value of 0.2%. The solvent is then completely removed from the yellowish solution obtained by spray drying in a commercial laboratory spray dryer, the Minispray Dryer 190 (Firma Büchi). A pale yellow product is obtained with the following properties: Content in NCO: 0.3% Content in uretdione groups (cale): 15.0% Total content in NCO (cale): 15.3% Melting point: 105 to lilac C2-a) modified polyisocyanide by polyisocyanate (analogously to DE-A 4 427 225) 1000 g (8.7 eq.) Of dodecanedioic acid are mixed under nitrogen with 200 g (1.0 eq.) Of a polyisocyanate based on hexamethylene diisocyanate exhibiting isocyanurate groups with an isocyanate content of 21.5% and a viscosity at 232C of 3,000 mPa.s as well as with 240 g (2.4 mol) of acetanhydride, heated to 1252C and stirred then at this temperature for 4 hours. The acetic acid originating in a gentle stream of N is then distilled and a colorless crystalline product with a melting range (TAD) of 84 to 104 ° C., a content of carboxyl groups (calculated as C02H, molecular weight = 45) is obtained. 11.8%, in carboxylic acid anhydride groups (calculated as C30, molecular weight = 72) of 15.6% and in nitrogen present in the form of amide and / or urea groups of 1.3%. The equivalent weight is calculated at 144 g / carboxyl equivalent.

Mixture of polyaddition compound Ba) containing uretdione groups and of the polyisocyanate modified C2-a) polyanhydride Following the preparation of the polyaddition compound Ba) containing uretdione groups described above, after reaching a free NCO content of 0 , 8%, is added in portions to the reaction mixture, at a temperature of 1052c, C2-a polyanhydride) modified by polyisocyanate, solid, in a proportion of 40% based on the total amount of the two components Ba) and C2-a) and after the complete melting of the polyanhydride it is continued stirring at this temperature for about 10 to 15 minutes. The melt is poured on a sheet for cooling and a solid resin is obtained, almost colorless, stable to storage, with the following properties: NCO content: 0.5% Content of uretdione groups (cale): 7.3% Total content in NCO (cale): 7.8% Equivalent weight (carboxyl equivalent): 360 g / eq. Melting point: 69 to 722C ß-hydroxyalkylamide D-a) 900 g (5.2 mol) of dimethyl adipate are mixed with 100 g (0.6 mol) of dimethyl glutarate, 1460 g (13.9 mol) of diethanolane and 5 g of potassium hydroxide in a stirred flask with a distillation device and heated to a temperature of 100 ° C. With this, the methanol originates from the reaction mixture. After about 200 g of methanol have been removed, a vacuum of about 150 mbar is connected to the reaction device, whereupon another approximately 100 g of methanol are distilled. The distillation bridge is then separated and the reaction mixture is contacted with 350 g of fresh methanol and 2 l of acetone. The precipitate that is deposited is filtered in vacuo, then washed with acetone and dried. A pale yellow powder with a melting point of 118 to 120 ° C is obtained. The equivalent weight amounts to 80 g / eq. of hydroxyethylamide groups. Example i 39.0 parts by weight of a polyester containing hydroxyl groups, which was obtained from 66.6 parts by weight of terephthalic acid, 38.2 parts by weight of neopentyl glycol, 5.3 parts by weight, are intimately mixed. of 1,6-hexanediol and 4.5 parts by weight of 1,1,1-trimethylolpropane and exhibits an OH number of 50 and a melting range (determined by differential thermoanalysis) of 55 to 602C, with 11.4 parts by weight of the polyaddition compound Ba) containing uretdione groups, corresponding to an equivalent ratio of total NCO to OH of 1: 1, 8.1 parts by weight of the polyisocyanate C2-a) modified by polyisocyanate and 4.5 parts by weight of the β-hydroxylamide Da), corresponding to a ratio of equivalents of carboxyl equivalents to groups reactive towards carboxyl and / or carboxylic acid anhydride groups of 1: 1, 1.0 parts by weight of a commercial leveling agent based on butyl polyacrylate (RModaflow Pili; Fir Monsanto), 1.0 parts by weight of tin (II) octanoate as a catalyst and 35.0 parts by weight of a common commercial white pigment (RBayertitan R-KB-4; Bayer AG) and then homogenized with the aid of a Buss mixer of type PLK 46 at 150 rpm and a temperature in the housing of 602c in the trailing area as well as on the shaft, or 1002C in the process part, reaching temperatures in the mass of 95 to 1052C. The solidified melt is milled with the aid of an ACM 2 ball sorting mill (Hosokawa Mikropul) with a 90 μm sieve and sieved. The powder thus obtained is sprayed with an ESB cup gun at a high voltage of 70 kV onto a degreased steel plate and hardened for 30 minutes at 170 and 1852C, respectively, to give smooth white lacquered matt lacquers. For layer thicknesses of about 60 μm, the following technical properties of lacquer are available: a) ET = Erichsen Depth, according to DIN 53 156. b) Brightness = Brightness according to Gardner; 202 or 602 of reflection angle c) Ac = Acetone test; DH = number of double runs with embedded cotton buffer Titration = 0 = intact film 1 = surface of the softened film 2 = film swollen to the bottom = matte (loss of brightness) Examples 2-6 Based on polyester containing hydroxyl groups described in Example 1, following the procedure described in Example 1, powder lakes of the following composition (parts by weight) were obtained. Example (comparison) (comparison) Polyester according to example 1 41.7 44.3 46.2 Polyaddition compound Ba) 12.2 13.0 13.5 Bb) C2-a polyanhydride) 5,4 5,7 Dodecanedioic acid β-hydroxyalkylamide Da) 3, 3 TGIC 3.7 Modaflow Pili 1.0 1.0 1.0. Tin Octanoate (II) 1.0 1.0 1.0 Bayertitan R-KB-4 35.0 35.0 35.0 The powders are sprayed with an ESB cup gun at a high voltage of 70 kV onto degreased steel sheets and harden for 30 minutes at 1852C, respectively. For layer thicknesses of 60 + 5 μm there are the following technical properties of lacquer: ») ET = Erichsen Depth, according to DIN 53 156. b) Brightness = Brightness according to Gardner; 20 0 or 602 of reflection angle c) Ac = Acetone test; DH = number of double runs with embedded cotton buffer Rating 0 = film intact 1 = surface of the softened film 2 = film swollen to the bottom = matt (loss of brightness) Comparative examples show that the addition of only another compound, for example of a component exhibiting carboxyl groups and / or carboxylic acid anhydride groups (comparison example 5) or of only one component exhibiting reactive groups to carboxyl groups and / or carboxylic acid anhydride (comparison example 6) to a polyurethane system composed of a polyester polyol and a polyaddition compound containing uretdione groups, leads to coatings that are not matte and exhibit only regular elasticities and stability properties. Example 7 (comparison) From 37.1 parts by weight of the polyester containing hydroxyl groups described in Example 1 and 10.9 parts by weight of polyaddition compound Ba) containing uretdione groups, corresponding to a ratio of equivalents of Total NCO at OH of 1: 1, as well as 14.7 parts by weight of a polyester containing carboxyl groups, which was obtained from 44.8 parts by weight of terephthalic acid, 6.8 parts by weight of acid isophthalic, 48.9 parts by weight of neopentyl glycol and 0.5 parts by weight of pentaerythritol and exhibits an acid number of 15.5 and a melting range (determined by differential thermoanalysis) of 65 to 702C, and 0.3 parts by weight of the ß-hydroxyalkylamide Da), corresponding to a ratio of equivalents of carboxyl groups to groups reactive towards carboxyl groups of 1: 1, following the procedure described in example 1 with 1.0 parts by weight of an agent current commercial leveling system of butyl polyacrylate ("Modaflow Pili; Monsanto), 1.0 parts by weight of tin (II) octanoate as a catalyst and 35.0 parts by weight of a common commercial white pigment (Bayertitan R-KB-4; Bayer AG), a white lacquer is obtained. The powder is sprayed with an ESB cup gun at a high voltage of 70 kV onto a degreased steel sheet and hardens for 30 minutes at 1852C. A glossy lacquer film is obtained which, for a layer thickness of about 65 μm, exhibits the following properties: ET = Erichsen depth, according to DIN 53 156. b) Brightness = Brightness according to Gardner; 202 or 602 of reflection angle Ac = Acetone test; DH = number of double runs with embedded cotton pad Titration = 0 = intact film 1 = softened film surface 2 = film swollen to the bottom m = matt (loss of brightness) The comparison example shows that the addition of a combination of a carboxylated high molecular weight polyester and a crosslinking agent reactive with carboxyl groups to a polyurethane system composed of a polyester polyol and a polyaddition compound containing uretdione groups, leads not to a matt coating, but a bright one that, in addition, exhibits stability to solvents only regular.

Example 8 From 39.7 parts by weight of the polyester containing hydroxyl groups described in Example 1, 19.1 parts by weight of the mixture obtained, according to the procedure described above, of the polyaddition compound Ba) containing groups uretdione with the C2-a) polyanhydride modified by isocyanate and 4.2 parts by weight of the ß-hydroxyalkylamide Da), corresponding to a ratio of total NCO to OH and of carboxyl equivalents to groups reactive with carboxyl groups and / or carboxylic acid anhydride of 1: 1 respectively, following the procedure described in Example 1 with 1.0 parts by weight of a common commercial leveling agent based on polyacrylate ("Modaflow Pili; Firma Monsanto), 1.0 parts by weight of tin (II) octanoate as catalyst, 1.1 parts by weight of Flammruß 101 (Signature Degussa) as well as with 33.9 parts by weight of a commercially available filler (Blanc Fix M, Firma Sachtleben) , they get e a powder coat pigmented in black. The powder is then sprayed with an ESB cup gun at a high voltage of 70 kV onto a degreased steel sheet and hardens for 30 minutes at 1852C. The matte black coating obtained shows the following technical properties of lacquer (thickness of the layer: about 70 μm): ET = Erichsen depth, according to DIN 53 156. Gloss = Gloss according to Gardner; 202 or 602 of reflection angle Ac = Acetone test; DH = number of double runs with embedded cotton buffer Evaluation = o = intact film 1 = surface of the softened film 2 = film swollen to the bottom It is noted that, in relation to this date, the best method known to the applicant to carry out the aforementioned invention is e-1 which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property:

Claims (1)

1. CLAIMS 1. Powdered lacquer characterized because it contains: A) a binder component that exhibits hydroxyl groups, present in solid form below 40 C and in liquid form above 1302c, with an OH number of 25 to 200 and a weight medium molecular weight (calculated from functionality and hydroxyl content) of 400 to 10,000, B) a polyaddition compound that exhibits uretdione groups and, if applicable, free isocyanate, present in solid form below 40 c and in the form liquid above 1252C, based on aliphatic and / or cycloaliphatic diisocyanates, C) a component exhibiting carboxyl and / or carboxylic acid anhydride, present in solid form below 40 C and in liquid form above? 602C , composed of at least one component selected from Cl) dicarboxylic (cyclo) aliphatic acids with 4 to 20 carbon atoms, C2) monomer anhydrides and / or polymers, optionally modified, of such dicarboxylic acids s and C3) aliphatic hydroxycarboxylic acids with 4 to 13 carbon atoms, D) a component exhibiting groups reactive towards carboxyl and / or carboxylic acid anhydrides of an average molecular weight of 200 to 5,000, and, if appropriate, ) Adjuvant substances and additives known from powder coating technology, with the proviso that components A), B), C) and D) must be present in proportions such that each hydroxyl group of component A) corresponds to them from 0.6 to 1.4 isocyanate groups of component B), the isocyanate groups of component B being understood as the sum of isocyanate groups present in the form of a dimer, such as uretdione groups and free isocyanate groups, to each carboxyl equivalent of component C ) correspond to 0.3 to 1.5 groups reactive towards carboxyl groups and / or carboxylic acid anhydride of component D), one carboxyl group corresponding to one and one anhydride group of carboxylic acid to two equ carboxyl ivalents, and that the proportion of components C) and D) amounts to 10 to 40% by weight of the total amount of components A), B), C) and D). Powder coating according to claim 1, characterized in that component A) consists of a polyester containing hydroxyl groups with a softening temperature - determined by differential thermoanalysis (TAD) - which is within the temperature range of 40 to 120 ° C, an OH number of 25 to 200 and an average molecular weight (calculated from functionality and hydroxyl content) of 1,000 to 5,000. Powder lacquer according to claim 1, characterized in that component B) consists of a polyaddition compound based on isophorone diisocyanate which exhibits uretdione groups and, optionally, free isocyanates. Powder coating according to claim 1, characterized in that component B) consists of a polyaddition compound with a) a content of free isocyanate groups (calculated as NCO, molecular weight = 42) of 0 to 2% by weight, b) a content of uretdione groups (calculated as C: N20> = molecular weight = 84) from 3 to 16% by weight, c) a content of urethane groups (calculated as CHNO,; molecular weight = 59) of 10 to 22% by weight, d) a content of carboxylic acid ester groups (calculated as C02, molecular weight = 44) from 0 to 20% by weight, and / or e) a carbonate group content (calculated as CO,; molecular weight = 60) from 0 to 25% by weight, with the proviso that the combined content of carboxylic acid ester groups and carbonate groups amounts to at least 1% by weight. Powder lacquer according to claim 1, characterized in that component C) is composed of at least one (poly) dicarboxylic acid anhydride, based on a saturated aliphatic dicarboxylic acid exhibiting 4 12 carbon atoms, modified by polyisocyanates having a carboxyl group content (calculated as C02H, molecular weight = 45) of 0.5 to 30% by weight, a content of carboxylic acid anhydride groups (calculated as CO, = molecular weight = 72) 35% by weight and a nitrogen content, present attached in amido and / or urea groups, from 0.2 to 8% by weight. Powder lacquer according to claim 1, characterized in that the component D) is composed of trisglicidyl isocyanurate and / or its oligomers or by a β-hydroxyalkylamide based on saturated dicarboxylic acids with 4 to 12 carbon atoms. Powdered lacquer according to claim 1, characterized in that component D) is composed of a β-hydroxyalkylamide obtained by transformation of diethanolamine with a mixture of 9 parts by weight of dimethyl adipate and 1 part by weight of dimethyl glutarate. Powder coating according to claim 1, characterized in that components A), B), C) and D) are present in proportions such that each hydroxyl group of component A) corresponds to 0.8 to 1.2 isocyanate groups of component B), the isocyanate groups of component B) being understood as the sum of the isocyanate groups present in the form of a dimer such as uretdione groups and free isocyanate groups, corresponding to each carboxyl equivalent of component C) of 0.4 to 1,2 groups of component D) reactive towards carboxyl and / or carboxylic acid anhydride, and the proportion of components C) and D) amounts to 15 to 35% by weight of the total amount of components A) , B), C) and D). Use of the powder coating according to claim 1 for the production of matt coatings. Use of the powder coating according to claim 1 for the coating of heat-resistant substrates.