NZ299849A

NZ299849A - Powder coatings based on acrylate copolymers containing glycidyl ether groups; preparation includes radical copolymerisation

Info

Publication number: NZ299849A
Application number: NZ299849A
Authority: NZ
Inventors: Andreas Kaplan; Rene Gisler; Albert Reich
Original assignee: Inventa Ag
Priority date: 1995-12-01
Filing date: 1996-11-29
Publication date: 1998-05-27
Also published as: JPH09268262A; JP3325192B2; KR970042868A; EP0776949B1; CN1070899C; NO965073D0; DE59609002D1; ES2175012T3; EP0776949A3; CN1156161A; ZA969422B; BR9605764A; AR005243A1; IL119611A; NO965073L; HK1001622A1; IL119611A0; AU7176296A; DE19544930C2; ATE215590T1

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number £99849 New Zealand No. 299849 International No. PCT/ TO BE ENTERED AFTER ACCEPTANCE AND PUBLICATION Priority dates: 01.12.1995; Complete Specification Filed: 29.11.1996 Classification:^) C08J3/12; B29B9/00 Publication date: 27 May 1998 Journal No.: 1428 Title of Invention: Thermosetting powder coating and method of the preparation thereof Name, address and nationality of applicant(s) as in international application form: EMS-INVENTA AG, a Swiss body corporate of Selnaustrasse 16, CH-8002 Zurich, Switzerland NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION 299849 No: Date: NEW ZEALAND PATENTS ACT, 1953 N.z. PATT.NT -~'T 2 9 NOV 1996 RECEIVED COMPLETE SPECIFICATION THERMOSETTING POWDER COATING AND METHOD OF THE PREPARATION THEREOF We, EMS-INVENTA AG, a Swiss body corporate, of Selnaustrasse 16, CH-8002 Zurich, Switzerland, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 299849 This invention relates to a method of preparing powder coatings based on acrylate copolymers containing glycidyl ether groups, appropriate curing agents and/or pigments and/or fillers and/or additives, wherein the acrylate copolymer containing glycidyl ether groups is obtainable by polymer analog reaction of hydroxy functional acrylate copolymers with epihaloalkanes. Furthermore, this invention relates to powder coatings obtainable by the above mentioned method and to the use of the powder coating for the preparation of protective layers. Acrylate copolymers containing epoxy groups and the use thereof as binding agents in powder coatings are known. They are disclosed for example in US-3 781 379, US-4 042 645, and US-4 346 144. Polybasic acids, preferably dibasic acids, anhydrides thereof or substances forming a dibasic acid under curing conditions are used there as curing agents. Even other carboxyl functional compounds, such as for example amorphous and/or semicrystalline polyester resins and/or acrylic resins having unreacted carboxyl groups can be used principally as curing agents. The copolymers as described in the above patents all contain glycidyl acrylate or methacrylate. The residue of the copolymer consist of other unsaturated monomers, i.e. it is the matter of acrylate copolymers containing glycidyl ester groups. The preparation of monomer glycidyl (meth)acrylate is not easy from the technical view, since glycidyl (meth)acrylate polymerizes easily, and the isolation of the pure monomers is very problematic. Apart from the short shelf life of glycidyl (meth)acrylate the high toxicity thereof also makes problems during fabrication. Therefore, the preparation of acrylate polymers containing glycidyl ester groups by copolymerization of glycidyl (meth)acrylate is problematic and not recommended. A further disadvantage of this process is, that water can not be used as reaction medium. US-3 294 769 discloses a method of preparing acrylate polymers containing glycidyl ester groups by reaction of carboxyl functional acrylate polymers with epichlorohydrin. The esterification of methyl methacrylate polymers and the following reaction with epichlorohydrin is described by Sandner et al (see Angew. Makromol. Chemie 181 (1990), 171-182, and Makromol. Chem. 192 (1991), 762-777). 3 It is an objective of the present invention to provide a new simple method of preparing thermosetting powder coatings based on acrylate copolymers containing glycidyl ether groups, containing specific acrylate copolymers as binding agents and avoiding the above mentioned disadvantages of the prior art. Accordingly, in one aspect, the present invention consists in a method of preparing powder coatings based on acrylate copolymers containing glycidylether groups characterized in that a hydroxy functional acrylate-copolymer (D) is prepared in a first step by radical copolymerisation, subsequently converted to a glycidylether-containing acrylate-copolymer by reaction with epihaloalkanes and processed into a powder coating by extrusion of component (A) together with component (B), wherein B is an aliphatic and/or cycloaliphatic polybasic acid and/or anhydrides thereof and/or a polyol-modified anhydride of a polybasic acid and/or amorphous or semicristalline carboxy functional copolyester resin ^nd/or carboxy functional acrylic resins and optionally additional pigments and/or fillers and/or additives (C). A preferred embodiment of the present invention consists in the above method being further characterized in that an extrudate is prepared in the molten state by common extrusion of all the formulated components and, additionally, standard pigments and/or fillers and/or additives at a temperature between 60 and 140°C, subsequently cooled down, ground up and sieved to a grain size of < 90 pm. In other aspects, the present invention consists in a powder coating obtained by the above methods, and in the use of that powder coating for the preparation of protective layers. Surprisingly it is confirmed, that acrylate copolymers containing glycidyl ether groups can be prepared in a polymer analog reaction by reacting hydroxyl functional acrylate copolymers with epihaloalkanes. 4 Therefore, the subject matter of the invention is a method of preparing thermosetting powder coatings containing: A) an acrylate copolymer containing glycidyl ether groups, B) an aliphatic and/or cycloaiiphatic polybasic acid and/or the anhydride thereof and/or a polyol-modified anhydride of a polybasic acid and/or amorphous or semicrystalline carboxyl functional copolyester resins and/or carboxyl functional acrylic resins, C) optionally fillers and/or pigments and/or additives, wherein the acrylate copolymer containing glycidyl ether groups (A) has a molecular weight (Mw) of ">,000 to 30,000 and a glass transition temperature of 20 to 120°C and can be obtained by preparing in a first step a copolymo. (D) having hydroxyl groups which is then converted in further steps by the reaction with epihaloalkanes. The components (A), (B), and optionally (C) are extruded together to finely form the powder coating. The copolymer (D) is preferably obtained by copolymerization of the following mixture of monomers: (a) 0 to 70 parts by weight of methyl (meth)acrylate, (b) 0 to 60 parts by weight of aikyl or cycloalkyl ester of acrylic and/or methacrylic acid having 2 to 18 C-atoms in the alkyl or cycloalkyl moiety, (c) 0 to 90 parts by weight of vinyl aromatic compounds, (d) 0 to 60 parts by weight of hydroxyl ester of acrylic and/or methacrylic acid, wherein the total sum of the parts by weight of the components (a) to (d) is 100. Hydroxyl functional acrylate copolymers with an OH-number from 10 to 400 are preferred, preferably 20 to 300 [mg KOH/g]. 299849 The monomers (b) are preferably (cyclo)alkyl ester of acrylic of methacrylic acid with 2 to 18 carbon atoms in the (cyclo)alkyS rest. Examples of appropriate monomers (b) are ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, Isobutyl (meth)acrylate, tertbutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl methacrylate, Neopentyl methacrylate, isobornyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate and stearyl methacrylate. Mixtures thereof can also be used. Monomers (c) include for example styrene, vinyl toluene and a-ethyl styrene. Suitable monomers (d) are hydroxylalkyl ester of acrylic and/or methacrylic acid with 2 to 6, preferably 2 to 4 carbon atoms in the hydroxyl moiety, such as for example 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, i.e. the resulting mixture of isomeres obtained by reacting propylene oxide with (meth)acrylic acid, 4-hydroxy-n-butyl acrylate or the products of reacting e-caprolactone with the above mentioned hydroxy-alkyl ester. The term "hydroxyalkyl ester" should also be interprted to include comprise compounds having ester groups resulting from the reaction of e-caprolactone with hydroxy alkyl ester having 2 to 6 carbon atoms in the hydroxyl moiety. Furthermore, reaction products of glycidyl (meth)acrylate with saturated monocarboxylic acids and reaction products of (meth)acrylic acid with saturated monoepoxides having possibly additional OH-groups can also be regarded as "hydroxylalkyl ester" of (meth)acrylic acid and are also suitable as monomers (d). The copolymers can be prepared by copolymerization of the above mentioned monomers (a) to (d) by using the conventional radical polymerization methods, such as for example solution-, emulsion-, pearl- or solid-phase polymerization. Monomers are copolymerized at temperatures of 60 to 160°C, preferably 80 to 150°C in the presence of radical initiators and optionally molecular weight modifiers. The hydroxyl functional acrylate copolymers are prepared in inert solvents. Suitable solvents are for example aromatic solvents, such as benzene, toluene, xylene; ester, such as ethyl acetate, butyl acetate, hexyl acetate, heptyl acetate, methyl glycol acetate, ethyl glycol acetate, methoxypropyl acetate; ethers, such as tetrahydrofuran, dioxane, diethylene glycol dimethyl ether; ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl-n-amyl ketone, methyl isoamyl ketone or any mixtures thereof. 6 The preparation of the copolymers can be carried out continuously or discontinuously. Generally, the monomer mixture and the initiator are fed at a uniform rate and continuously into a reactor for polymerization and .simultaneously, the appropriate amount of the polymer is carried off continuously. Preferably, almost chemically homogeneous copolymers are prepared in this way. Almost chemically homogeneous copolymers can also be produced by feeding the reaction mixture with constant speed into a stirred vessel without carrying off the polymer. For example, a part of the monomers can also be first dissolved in the above described solvents and then the remaining monomers and additives can be fed separately or together into the vessel at the reaction temperature. Generally, polymerization is carried out under atmosphere pressure; however, it can also be carried out at pressures up to 25 bar. The initiators are used in amounts of 0.05 to 15 percent by weight based on the total amount of the monomers. Suitable initiators are conventional radical starters, such as for example aliphatic azo compounds, such as azodiisobutyronitrile, azo-bis-2-methyl valeronitrile, 1,1'-azo-bis-1-cyclohexylnitrile and 2,2'-azo-bis-isobutyro alkyl ester; symmetric diacyl peroxides, such as for example acetyl, propionyl or butyryl peroxide, substituted benzoyl peroxides having bromo, nitro, methyl or methoxy groups, lauroyl peroxides; symmetric peroxydicarbonates, for example tert-butyl perbenzoate; hydroperoxides, such as for example tert-butyl hydroperoxide, cumenehydroperoxide; diaikyl peroxides, such as dicumyl peroxide, tert-butyl cumyl peroxide or di-tert-butyl peroxide. Modifiers can be used during the preparation for modifying the molecular weight of the copolymers. Preferred examples include mercaptopropionic acid, tert-dodecyl mercaptan, n-dodecyl mercaptan or diisopropyl xanthogene disulfide. The modifiers can be added in amounts of 0.1 to 10 percent by weight based on the total amount of the monomers. The resulting solutions of the copolymers during the copolymerization can be subjected without further workup to an evaporation process or degassing process, wherein the solvent is removed for example in an evaporation extruder or spray-dryer at about 120 to 299849 160°C and 100 to 300 mbar, to obtain the copolymers to be used according to this invention. The reaction of the hydroxyl functional copolymers D with epihaloalkanes to produce acrylate copolymers A containing glycidyl ether groups according to the invention is carried out by the conventional method of preparation of glycidyl ether. The glycidyl ether of hydroxyl functional acrylate copolymers are obtained by reacting the hydroxyl functional acrylate copolymer with epihaloalkanes. Generally, this reaction is carried out in a two-step process. In the first step an epihaloalkane is added to the hydroxyl group of an acrylate copolymer, wherein a halohydrin ether is formed. This reaction is catalyzed by Lewis acids, such as for example boron trifluoride, stannic tetrachloride, etc. Suitable solvents are inert solvents, such as for example benzene, toluene, chloroform, etc., or the reaction may be carried out in an excess of epihaloalkane, which acts simultaneously as a solvent. In the following second step the acrylate copolymer containing glycidyl ether groups is formed by dehydrohalogenation in an inert solvent, a preferred example being toluene, by using an aqueous basic solution, preferred example being sodium hydroxide solution. The resulting salt solution of the reaction and water form together with the water of the basic solution a aqueous waste liquor having a greater specific gravity, which can easily be separated from the organic layer after the reaction. The reaction temperature of the first step is about 80°C and the reaction time is about 30 min. The reaction temperature of the second step is 50°C and the reaction time is about 60 min. The reaction of the hydroxyl functional acrylate copolymer can also be carried out in a single step of a multi phase reaction. It concerns a phase transfer catalyzed two-phase reaction between the hydroxyl functional acrylate copolymer, an epihaloalkane and an aqueous basic solution, preferably sodium hydroxide solution. Quaternary ammonium and/or phosphonium compounds are used as phase-transfer catalysts, for example benzyl trimethyl ammonium bromide, tetramethyl ammonium bromide, benzyl trimethyl 299849 ammonium chloride, ethyl triphenyl phosphonium bromide and butyl triphenyl phosphonium chloride, preferably benzyl trimethyl ammonium bromide. The reaction temperature is 60°C and the reaction time is about 60 min. A variation of the phase-transfer process is the so called azeotrope-process, wherein during the two-phase reaction the existing and resulting water is destilled azeotropically with epihaloalkane under vacuum. Preferred examples of suitable epihaloalkanes are 1-chloro-2,3-epoxy propane (epichlorohydrin), 1-chloro-2-methyl-2,3-epoxy propane and 1-chloro-2,3-epoxy butane. 1-chloro-2,3-epoxy propane is preferred. Certainly, further epihaloalkanes can be used successfully, for example epibromohydrin. The acrylate copolymers A containing glycidyl ether groups have a glass transition temperature of 20 to 120°C. The preferred glass transition temperature is in the range of 30 to 90°C. The molecular weights (Mw) are generally 1,000 to 30,000, preferably 1,000 to 20,000. The epoxy number of the acrylate copolymer containing glycidyl ether groups according to the present invention are in the range of 0.018 to 0.510, preferably from 0.035 to 0.412 [equiv./100 g]. Aliphatic polybasic acids, preferably dibasic acids, such as for example adipic acid, pimeiic acid, suberic acid, azelaic acid, sebacic acid, malonic acid, succinic acid, glutaric acid, 1,12-dodecanedicarboxylic acid, etc. can be used as curing agents - component B. The anhydrides of these acids can also be used, for example glutaric anhydride, succinic anhydride, and the polyanhydrides of these dicarboxylic acids. These poly-anhydrides are obtained by intermolecular condensation of the above mentioned aliphatic dibasic dicarboxylic acids. Examples are adipic acid (poly)anhydride, azelaic acid (poly)anhydride, sebacic aciu (poly)anhydride, dodecanedicarboxylic acid (poiy)anhydride, etc. The polyanhydrides have a molecular weight (weight average of molecular weight based on polystyrene standard) of 1,000 to 5,000. The polyanhydrides can also be modified with polyol. 299849 The polyanhydrides can also be used in a mixture with the aliphatic dibasic dicarboxylic acid as curing agents or in a mixture with hydroxycarboxylic acids having melting points between 40 und 150°C, for example 12-hydroxystearic acid, 2- or 3- or 10-hydroxyoctadecanoic acid, 2-hydroxymyristic acid. Cycloaliphatic dicarboxylic acids, such as for example 1,4-cyciohexane dicarboxylic acid or the polyanhydrides thereof can also be used as curing agents. Other suitable curing agents include also amorphous or semicrystalline copolyesters. The amorphous as well as the semicrystalline copolyesters can be prepared by condensation processes for polyesters known in the prior art (esterification and/or trans-esterification). Suitable catalysts, such as for example dibutyl tinoxide or tetrabutylate titanium, can also be used optionally. Suitable amorphous carboxyl functional copolyester resins have an acid number of 10 to 200 [mg KOH/g] and a glass transition temperature of >40°C. Amorphous carboxyl functional copolyester contain mainly aromatic polybasic carboxyl acids as acid components, such as for example terephthalic acid, isophthalic acid, phthalic acid, pyromellitic acid, trimellitic acid, 3,6-dichlorophthalic acid, tetrachlorophthalic acid, and if obtainable the anhydride, chloride or ester thereof. Usually, they contain at least 50 Mol-% terephthalic acid and/or isophthalic acid, preferably 80 Mol-%. The remainder of the acid component (difference to 100 mole-%) consists of aliphatic and/or cycloaliphatic polybasic acids, such as for example 1,4-cyclohexyldicarboxylic acid, tetrahydrophthalic acid, hexahydroendomethyleneterephthalic acid, hexachlorophthaiic acid, azelaic acid, sebacic acid, adipic acid, dodecandicarboxylic acid, succinic acid, maleic acid, or dimer fatty acids, hydroxycarboxylic acids, and/or lactones, such as for example 12-hydroxystearic acid, e-caprolactone or neopentyl glycol hydroxypivalic acid ester, can also be used. Monocarboxylic acids, such as for example benzoic acid, tert-butylbenzoic acid, hexahydrobenzoic acid and saturated aliphatic monocarboxylic acids may also be rvJded in minor amounts during the preparation. 299849 Furthermore, aliphatic diols, such a - for example ethylene glycol, 1,3-propane diol, 1,2-propane diol, 1,2-butane diol, 1,3-butane diol, 2,2-dimethyl-1,3-propane diol (neopentyl glycol), 2,5-hexane diol, 1,6-hexane diol, 2,2[bis-(4-hydroxycyclohexyl)]propane, 1,4-dimethylol c.yclohexane, diethylene glycol, dipropylene glycol and 2,2-bis-[4-(2-hydroxy)]phenyl propane can be used. Polyols, such as for example glycerin, hexane trioles, pentaerythritol, sorbitol, trimethylol ethane, trimethylol propane, and tris(2-hydroxy)isocyanurate can be used in minor amounts. Epoxy compounds can also be used instead of diols or polyols. The amount of neopentyl glycol and/or propylene glycol as the alcohol component is preferably at least 50 mole-% based on the total weight of the acids. Suitable semicrystalline polyesters have an acid-number of 10 to 400 [mg KOH/g] and a well defined DSC-melting point. Semicrystalline polyesters are condensation products of aliphatic polyols, preferably aliphatic diols and aliphatic and/or cycloaliphatic and/or aromatic polybasic carboxylic acids, preferably dibasic acids. Preferred examples of aliphatic polyols are: ethylene glycol (1,2-ethanol diol), propylene glycol (1,3-propane diol), butylen glycol (1,4-butane diol), 1,6-hexane diol, neopentyl glycol, dimethylol cyclohexane, trimethylol propane etc. Preferred are aliphatic diols, such as for example ethylene glycol, butylene glycol or 1,6-hexane diol. Suitable polybasic carboxylic acids are aliphatic dicarboxylic acids, preferably dicarboxylic acids, such as for example adipic acid, azelaic acid, sebacic acid, dodecane dicarboxylic acid, succinic acid, undecanedicarboxylic acid, and aromatic dicarboxylic acids, such as for example terephthalic acid, isophthalic acid, phthalic acid, and the hydrogenation products thereof, such as for example 1,4-cyclohexanedicarboxylic acid. Preferred are aliphatic dicarboxylic acids having 6 to 12 carbon atoms. Mixtures of different polyols and polybasic carboxylic acids can certainly be used. Suitable carboxyl functional acrylate polymers have an acid number of 10 to 400 [mg KOH/g]. The composition and preparation is the same as that of to carboxyl functional acrylate copolymer D. Mixtures of various suitable curing agents can also be used in thermosetting powder coatings or powder coating compositions. 299849 The amount of the anhydrides employed as curing agents - component B - and the acids, based on the acrylic resin, is variable over a wide range and is related to the amount of the epoxy groups in the acrylic resin. Generally, a molar ratio of carboxyl groups or anhydride groups to epoxy groups is 0.4 to 1.4 :1, preferably 0.3 to 1.2 :1. Of course, any of the standard pigments and/or fillers and/or additives for the preparation and the use of powder coatings can be added to the powder coating system according to this invention. The additives are selected from the group of promoters, levelling and degassing agents, heat-, UV-, and/or HALS-stabilizers and/or tribo additives and, if required, dulling agents, such as for example waxes. The powder coatings according to this invention are preferably prepared in the molten state by common extrusion of all the formulated compounds at temperatures between 60 to 140°C. Subsequently the extrudate is cooled down, ground up and sieved to a grain size of smaller than 90 t*m. In principle, other methods are also suitable for the preparation of the powder coatings, such as for example mixing the formulated compounds in solution and followed by precipitation or removal of the solvents by destination. The application of the powder coatings according to this invention is carried out by standard methods for powder coatings, for example by electrostatic spray-coating (corona or tribo) or by fiuidized bed-coating. The preparation and the properties of the thermosetting powder coating compositions according to this invention are explained with reference to the following examples. 299849 Preparation of the Hydroxy Functional Acrylate Copolymers Example 1 General Preparation Component I (see Table 1) is placed In a special steel reactor having a stirring, a cooling and a heating equipment and an electronic temperature control system. Then component II component III (see Table 1) are added together slowly over a period of 3 hours, during which time the reaction mixture is refluxed. After the addition of component II and component III is finished, the reaction mixture is refluxed for further 2 hours. Afterwards the solvent is removed under vacuum from the reaction mixture. Table 1 Hydroxyl Group containing Acrylate Copolymers (Indications of weight in grams) Example 1 Example 2 Resin no. I II Component 1 xylene 1,000.00 1,000.00 Component II di-tert-butyl peroxide 46.25 46.25 xylene 78.75 78.75 Component III hydroxy ethyl methacrylate 537.43 429.39 n-butyl acrylate 185.00 185.00 methyl methacrylate 780.70 888.23 styrene 809.38 809.38 mercaptopropionic acid 57.90 57.90 299849 Table 2 Properties Examples 1 to 2 Example 1 Example 2 Resin no. I II OH-number Fmg OH/al 98.0 78.0 Tg [°C1 (calculated) 71 73 molecular weight (Mw) 7,900 7,800 Preparation of the Acrylate Copolymers containing Glycidyl Ether Groups according to this Invention Examples 3 to 6 Example 3 In a 20 liter reactor, equipped with a thermometer, a mechanical stirrer, a reflux-column and a heating mantle, 560 g of resin no. 1 are dissolved in 2,000 g of toluene. After addition of 18 ml of boron trifluoride-ethyl ether adduct the temperature is raised to 80°C and 100 g of epichlorohydrin are added dropwise over a period of 1 hour. Afterwards it is stirred for 30 minutes at 80°C and then cooled down to 50°C. After the addition of 200 g of aqueous sodium hydroxide (22%) is stirred for a further hour at 50°C. The aqueous phase !s then separated. After vacuum destination of the organic phase at a temperature of 130°C under reduced pressure (1 mm Hg) resin no. 3 (properties, see Table 3) is obtained. 14 Example 4 299849 In a 20 liter reactor, equipped with a thermometer, a mechanical stirrer, a reflux-column and a heating mantle, 560 g of resin no. 1 is dissolved in 2,000 g of toluene and 1,000 g of epichlorohydrin at 60°C. After the addition of 18.6 g of benzyl trimethyl ammonium chloride, 200 g of aqueous sodium hydroxide (22%) is added and the mixture is stirred for 1 hour at 60°C. The aqueous phase is then separated. After vacuum destination of the organic phase at a temperature of 130°C under reduced pressure (1 mm Hg) resin no. IV (properties, see Table 3) is obtained. Example 5 In a 20 liter reactor, equipped with a thermometer, a mechanical stirrer, a reflux-column and a heating mantle, 700 g of resin no. 1 is dissolved in 2,000 g of toluene. After addition of 18 ml of boron trifluoride-ethyl ether adduct the temperature is raised to 80 °C and 100 g of epichlorohydrin is added dropwise over a period of 1 hour. The mixture is then stirred at 80°C for a further 30 minutes and then cooitid down to 50 °C. After addition of 200 g of aqueous sodium hydroxide (22%) the mixture is stirred for a further hour at 50°C. The aqueous phase is then separated. After vacuum destination of the organic phase at a temperature of 130°C under reduced pressure (1 mm Hg) resin no. V (properties, see Table 3) is obtained. Example 6 In a 20 liter reactor, equipped with a thermometer, a mechanical stirrer, a reflux-column and a heat mantle, 700 g of resin no. 1 is dissolved in 2,000 g of toluene and 1,000 g of epichlorohydrin at 60°C. After the addition of 18.6 g of benzyl trimethyl ammonium chloride, 200 g of aqueous sodium hydroxide (22%) is added and the mixture is stirred for 1 hour at 60°C. The aqueous phase is then separated. After vacuum destination of the organic phase at a temperature of 130°C under reduced pressure (1 mm Hg) resin no. VI (properties, see Table 3) is obtained. 299849 Table 3 Properties Examples 4 to 6 Example 3 Er .ample 4 Example 5 Example 6 Resin no. III IV V VI starting resin I I II II epoxy number ' [equiv./100 g] 0.161 0.160 0.131 0.132 Tg [°C] (calculated) 69 70 70 71 molecular weight (Mw) 8,500 8,500 8,300 8,300 Preparation of the Powder Coating Examples 7 and 8 830 parts by weight of the resin III or resin IV, 160 parts by weight of dodecanedicarboxylic acid, 5 parts by weight of Resiflow PV 88 and 5 parts by weight of benzoin are dry-mixed in a Henschel mixer at 700 rpm for 30 seconds, and then extruded on a Buss-Co-kneader (PLK 46) at a heat-mantle-temperature of 100°C, cooled screw and a screw-turn of 150 rpm. The extrudate is cooled down, ground up and sieved to a grain smaller than 90 ^m. The powder coatings are applied electrostatically (corona or tribo) to alumina steel panels (Q-panel AI-36 5005 H 14/08 (0.8 mm) and cured at a temperature of 200°C and a time of 15 minutes. Table 4 shows the properties of the Examples 7 to 10. Example 9 and 10 850 parts by weight of resin III or resin IV, 140 parts by weight of dodecanecarboxyiic acid, 5 parts by weight of Resiflow PV 88 and 5 parts by weight of benzoin are dry-mixed in a Henschel-mixer at 700 rpm during 30 seconds and then extruded on a Buss- 299849 Co-kneader (PLK 48) at a heat-mantle-temperature of 100°C, cooled screw and a screw-turn of 150 rpm. The extrudate is cooled down, ground up and sieved to a grain size smaller than 90 ium. The powder coatings are applied electrostatically (corona or tribo) to alumina steel panels and cured at a temperature of 200°C and a time of 15 minutes. Table 4 shows the properties of the Examples 7 to 10. </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 239849 Table 4 Example 7 Example 8 Example 9 Example 10 Resin III IV V VI gelling time Kofler-heating- bank 200°C 30 31 27 28 gloss (60° DIN 67530) 109 108 108 109 Flow very good very good vary good very good slow penetration according to Erichsen (DIN 53156) (mm) 9.9 9.8 8.8 9.9 cross cutting (DIN 52151) 0 0 0 0 Impact (ASTM D 2794, reverse) 30 40 30 20 18 299849 WHAT HE CLAIM ISt

1. A method of preparing powder coatings based on acrylate copolymers containing glycidylether groups characterized in that a hydroxy functional acrylate-copolymer (D) is prepared in a first step by radical copolymerisa-tion, subsequently converted to a glycidylether-containing acrylate-copo-iymer by reaction with epihaloalkanes and processed into a powder coating by extrusion of component (A) together with component (B), wherein B is an aliphatic and/or cycloaliphatic polybasic acid and/or anhydrides thereof and/or a polyol-modified anhydride of a polybasic acid and/or amorphous or semicristalline carboxy functional copolyester resin and/or carboxy functional acrylic resins and optionally additional pigments and/or fillers and/or additives (C).

2. A method according to claim 1, characterized in that the radical copoly-merisation is carried out at temperatures of 60 to 160°C in the presence of radical initiators and optionally molecular weight modifiers.

3. A method according to claim 1 or 2, characterized in that the radical copolymerisation is carried out by solution polymerisation or solid phase polymerisation.

4. A method according to any one of claims 1 to 3, characterized in that the radical copolymerisation is carried out continuously by feeding the mixture of the monomers and the radical initiators at a uniform rate and conti-nously carrying off the copolymer.

5. A method according to any one of claims 1 to 4, characterized in that the "I 19 polymerisation is carried out at pressures up to 25 b

6. A method according to claim 5, characterized in that the carried out at atmospheric pressure. 28L&8A9

7. A method according to any one of claims 1 to 6, characterized in that the molecular weight modifiers are added in amounts of from 0.1 to 10 % by weight based on the total weight of the monomers.

8. A method according to any one of claims 1 to 7, characterized in that a compound selected from the group consisting of 1-chloro-2,3-epoxypro-pan (epichlorhydrin), 1-chloro-2-methyl-2,3-epoxy propane, 1 -chloro-2,3-epoxybutane, and epibromohydrin is used as the epihaloalkane.

9. A method according to any one of claims 1 to 8, characterized in that the hydroxy functional acrylate-copolymer (D) is obtained by copolymerisation of the following mixture of monomers: (a) 0 to 70 parts by weight of methyl(meth)acrylate; (b) 0 to 60 parts by weight of alkyl- or cycioalkylester of acrylic and/or methacrylic acid having 2 to 18 C-atoms.; (c) 0 to 90 parts by weight of vinylaromatic compounds; and (d) 0 to 60 parts by weight of hydroxylester of acrylic and/or methacrylic acid; wherein the total sum of the parts by weight of the components (a) to (d) is 100.

10. A method according to claim 9, characterized in that the hydroxy functional acrylate-copolymer (D) has a OH number from 10 to 400 mg KOH/g.

11. A method according to claim 10, characterized in that the OH number is from 20 to 300 mg KOH/g.

12. A method according to claim 9, characterized in that the alkyl- or cycloalkyiester are selected from the group consisting of ethyl(meth)acrylate, n- 299849 propyl(meth)acrylate, isopropyl(m8th)acrylate, n-butyl(meth)acryiate, isobutyl(meth)acrylate,tert-butyl(meth)acrylate,2-ethylhexyl(meth)acryla-te, cyclohexylmethacrylate, neopentylmethacrylate, isobornylmethacryla-te, 3,3,5-trimethylcyclohexylmethacrylate, stearylmethacrylate and mixtures thereof.

13. A method according to claim 9, characterized in that the vinyl aromatic compounds (c) are selected from the group consisting of styrene, vinylto-luene and a-ethylstyrene.

14. A method according to claim 9, characterized in that the hydroxyalkyl-ester of acrylic and/or methacrylic acid have 2 to 6 C-atoms in the hydroxy! moiety.

15. A method according to claim 14, characterized in that the hydroxyalkyl-ester of acrylic and/or methacrylic acid have 2 to 4 C-atoms in the hydroxyl moiety.

16. A method according to claim 1, characterized in that the aliphatic and/or cycloaliphatic polybasic acid of component (B) is a aliphatic carboxylic acid having 4 to 12 C-atoms or a cycloaliphatic dicarboxylic acid having 8 to 15 C-atoms.

17. A method according to any one of the preceding claims, characterized in that an extrudate is prepared in the molten state by common extrusion of all i the formulated components and, additionally, standard pigments and/or fillers and/or additives at a temperature between 60 and 140°C, subsequently cooled down, ground up and sieved to a grain size of < 90 //m.

18. Powder coating whenever obtained by the method according to claim 17. The use of the powder coating according to claim 18 for the preparation of protective layers. 21 299849 A use according to claim 19, substantially as herein described. A method of preparing powder coatings based on acrylate copolymers containing glycidylether groups, substantially as herein described with reference to Examples 3-10. A powder coating whenever prepared according to the method of any one of claims 1 to 16 and 21. Bms-wwarvm </div>