AU714502B2 - Thermosetting powder coating and method of the preparation thereof - Google Patents

Description

P/00/01Il Regulation 3-2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Thermosetting powder coating and method of the preparation thereof.

The following statement is a full description of this invention, including the best method of performing it known to us: MIPMELCM96319005.2 CD/99132022.6 1 THERMOSETTING POWDER-TYPE COATING COMPOSITIONS Field of the Invention This invention concerns powder coating compositions that are capable of being hardened or cured by means of heat, on the basis of acrylate copolymers containing epoxide groups, together with suitable curing agents and/or pigments and/or fillers and/or additives, whereby the epoxide-containing acrylate copolymer is capable of being prepared by a polymer-like reaction of hydroxyl-functional acrylate copolymers with epihaloalkanes.

Background of the Invention Acrylate copolymers containing epoxide groups and their use as binding agents in powder coatings are already known: See, for example, United States patents: U.S. Pat. No. 3,781,379, U.S. Pat. No. 4,042,645 and U.S. Pat No.

4,346,144 (incorporated herein by reference). As far as the hardeners are 15 concerned, use can be made in this connection of polybasic acids or, preferably, dibasic acids, and their anhydrides or substances that form a dibasic acid under the conditions that prevail during hardening. In principle, use can also be made of other carboxy-functional compounds as hardeners such as, for example, amorphous and/or semi-crystalline polyester resins and/or acrylate resins with free carboxy groups.

The copolymers that are described in the aforementioned patents all contain glycidyl acrylate, or, as the case may be glycidyl methacrylate. The rest of the copolymer consists of other unsaturated monomers, ie., one is dealing here with acrylate copolymers that contain glycidyl esters. The preparation of 25 monomeric glycidyl (meth)acrylate is not simple from a technical standpoint since glycidyl (meth)acrylate readily polymerizes, and the isolation of the pure monomer is very problematical. In addition to the short storage stability of glycidyl (meth)acrylate, its high toxicity also presents problems during processing. Thus 6@ 0 0 'i0 0 0*

S

OS

S

5.555 .n 0 C 0 *0 S 55.5 h S

S

CD/99132022.6 2 the preparation of acrylate polymers that contain glycidyl esters via the copolymerization of glycidyl (meth) acrylate is problematica! and not recommended. A further disadvantage of this process is that water cannot be used as the reaction medium.

U.S. Pat. No. 3,294,769 (incorporated herein by reference) describes, in general, a process for the preparation of acrylate polymers that contain glycidyl ester groups via the reaction of carboxy-functional acrylate polymers with epichlorohydrin.

The saponification of methyl methacrylate polymers and their subsequent reaction with epichlorohydrin has been investigated by Sandner et al. (see, Angew Makromol. Chem., 181: 171-192(1990) and Makromol. Chem., 192: 762-777 (1991)).

Summary of the Invention It is an object of the present invention to provide thermosetting powder 15 coating compositions comprising acrylate copolymers that contain epoxide groups, whereby the coating compositions contain special acrylate copolymers as binding Sagents. These compositions avoid the aforementioned disadvantages of the prior a art.

0 This and other objects are accomplished by the coating compositions, the processes for their preparation, the methods of using such coating compositions, the processes for preparing powder coatings as well as the powder coatings themselves, which are described in the following text and in the claims.

Detailed Description of the Invention 0* Surprisingly, it has been found that acrylate copolymers containing glycidyl 25 ether groups can be prepared in a polymer-like reaction by reacting hydroxylfunctional acrylate copolymers with epihaloalkanes.

CD/99132022.6 3 The subject of the invention is therefore thermosetting powder coating compositions comprising: a glycidyl ether-containing acrylate copolymer; an aliphatic and/or a cycloaliphatic polybasic acid and/or its anhydride and/or a polyol-modified anhydride of a polybasic acid and/or amorphous or semi-crystalline carboxy-functional copolyester resins and/or carboxy-functional acrylate resins; and, optionally, fillers and/or pigments and/or additives; whereby the glycidyl ether-containing acrylate copolymer has a molecular weight (Mw) of 1,000 to 30,000 and a glass transition temperature of to 1200C and is obtainable by, in a first step, preparing a copolymer that contains hydroxyl groups, which copolymer is then transformed, in further steps, into an epoxide-containing acrylate copolymer via reaction with epihaloalkanes. The copolymer is obtainable, in particular, via the copolymerization of a monomer mixture comprising the following components: 0 to 70 parts by weight of methyl (meth)acrylate; 0 to 60 parts by weight of (cyclo)alkyl esters of acrylic acid and/or methacrylic acid with 2 to 18 carbon atoms in the alkyl or, as the case may be, in the cycloalkyl residue; 0 to 90 parts by weight of vinyl aromatic compounds; and 1 to 95 parts by weight of hydroxyalkyl esters of acrylic acid and/or methacrylic acid, whereby the sum of the parts by weight of components through (d) 25 results in 100.

CD/99132022.6 4 Hydroxyl-functional acrylate copolymers are preferred with an OH number of 10 to 400 or, preferably, from 20 to 300 [mg KOH/g] The monomers are preferably (cyclo)alkyl esters of acrylic acid or methacrylic acid with 2 to 18 carbon atoms in the (cyclo)alkyl residue. Examples of especially suitable monomers are: ethyl (meth)acrylate, n-propyl (meth) acrylate, isopropyl (meth)acrylate, n-butyl (meth)-acrylate, isobutyl (meth)acrylate, tert.-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl methacrylate, neopentyl methacrylate, isobornyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate and stearyl methacrylate. Mixtures of the aforementioned monomers can also be used.

The monomers include, for example, styrene, vinyl-toluene and oaethylstyrene.

Suitable monomers are the hydroxyalkyl esters of acrylic acid and/or methacrylic acid with 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms, in the hydroxyl residue such as, for example, 2-hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate (ie. the mixture of isomers that is formed during the addition of propylene oxide to (meth)acrylate acid), 4-hydroxy-n-butyl acrylate or 6, also addition products of e-caprolactone to the aforementioned simple S hydroxyalkyl esters. Thus the term "hydroxyalkyl ester" will also encompass residues having ester groups which are produced by the addition of e-caprolactone to simple hydroxyalkyl esters with 2 to 6 carbon atoms in the hydroxyl residue. In addition, the reaction products of glycidyl (meth)acrylate with saturated monocarboxylic acids and the reaction products of (meth)acrylic acid with saturated monoepoxides, that can also carry OH groups, can be regarded as 25 "hydroxyalkyl esters" of (meth)acrylic acid and are therefore also suitable as monomers The preparation of the copolymers can be accomplished by copolymerization of the monomers to already described by conventional radical-type polymerization processes such as, for example, solution polymerization, emulsion polymerization, pearl polymerization or bulk CD/99132022.6 polymerization. In this connection, the monomers are copolymerized at temperatures of i600 to 1600°C preferably 80°C to 1500C. in the presence of a free radical initiator together, if necessary, with molecular weight regulators.

The preparation of the hydroxyl-functional acrylate copolymers may be carried out in inert solvents. Suitable solvents are, for example, aromatic compounds such as benzene, toluene and xylene; esters, such as ethyl acetate, butyl acetate, hexyl acetate, heptyl acetate, methylglycol acetate, ethylglycol acetate and 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 desired mixtures of such solvents.

The preparation of the copolymers can take place either continuously or discontinuously. Usually, the monomer mixture and the initiator are evenly and continuously metered into a polymerization reactor and the corresponding quantity of polymer is continuously drained off at the same time. Chemically virtually uniform copolymers also can advantageously be prepared in this way. Chemically virtually uniform copolymers also can be prepared by allowing the reaction mixture to run, at a constant rate, in a stirred vessel without draining off the polymerizate.

SA portion of the monomers can be introduced into the vessel, for example S 20 in solvents of the type described above, and then the rest of the monomers and S" the auxiliary agents can be introduced, separately or together, into this mixture at the reaction temperature.

In general, polymerization takes place under atmospheric pressure; however, it can also be carried out at pressures up to 25 bars. The initiators are 25 used in quantities of 0.05 to 15% by weight based on the total quantity of the monomers.

Suitable initiators include common radical-type initiators such as, for example, aliphatic azo compounds such as azodiisobutyro-nitrile, azo-bis-2methylvaleronitrile, 1,1'-azo-bis-1-cyclohexanecarbonitrile and the alkyl esters of CD/99132022.6 6 2,2'-azo-bis-isobutyric acid; symmetrical diacyl peroxides such as, for example, acetyl peroxide, propionyl peroxide or butyryl peroxide or benzoyl peroxides that have been substituted with bromine groups, nitro groups, methyl groups or methoxy groups, and lauryl peroxide; symmetrical peroxy dicarbonates, eg. tert.butyl perbenzoate, hydroperoxides such as, for example, tert.-butyl hydroperoxide, cumene hydroperoxide, dialkyl peroxides such as dicumyl peroxide, tertbutylcumyl peroxide or di-tert.-butyl peroxide.

In order to regulate the molecular weight of the copolymers, use can be made of conventional regulators during the preparation. One may designate, by way of example, mercaptopropionic acid, tert.-dodecylmercaptan, ndodecylmercaptan or diisopropyl-xanthogen disulfide. The regulators can be added in quantities of 0.1 to 10% by weight based on the total quantity of the monomers.

The solution of the copolymers generated during copolymerization can then be fed, without further processing, into an evaporation process or, as the case may be, a gas removal process, in which the solvent is removed, for example, in an evaporated extruder or spray dryer at approximately 120°C to 1600C under a vacuum of 100 to 300 mbars, and the copolymers that are to be used in

O

accordance with the invention are recovered.

0 9 The reaction of the hydroxyl-functional copolymers with epihaloalkanes to give the epoxide-containing acrylate copolymers according to the invention takes place in the manner that is usual for the preparation of glycidyl ethers.

The glycidyl ethers of the hydroxyl-functional acrylate copolymers are *i obtained by reacting the hydroxyl-functional acrylate copolymer with epihaloalkanes. As a rule, this reaction takes place in a two step process. In the first step, the epihaloalkane is added to the hydroxyl group of the acrylate copolymer, whereby a polyhalohydrin ether is formed. This reaction is catalyzed by Lewis acids such as, for example, boron trifluride, tin tetrachloride, etc. Inert o solvents such as, for example, benzene, toluene, chloroform, etc are suitable as the solvent, or the reaction can take place in an excess of the epihaloalkane, the solvent, or the reaction can take place in an excess of the epihaloalkane, CD/99132022.6 7 which simultaneously serves as a solvent.

In the subsequent two steps, the glycidyl ether acrylate copolymer is formed by means of a dehydrohalogenation reaction in an inert solvent, for example, using an aqueous caustic alkali solution, for example aqueous sodium hydroxide solution.

Together with the water from the caustic alkali solution, the salt solution and water that are generated during this reaction form a specifically heavier aqueous waste liquor that can be separated in a simple manner from the organic layer after the reaction.

The reaction temperature in the first stage amounts to approximately with a reaction time of approximately 30 minutes. The reaction temperature in the second stage amounts to 50°C with a reaction time of approximately 60 minutes.

The reaction of the hydroxyl-functional acrylate copolymer can also take place in a first sequential reaction. In this case, one is dealing with a phase- 15 transfer catalyzed two-phase reaction between the hydroxyl-functional acrylate copolymer, the epihaloalkane and an aqueous caustic alkali solution, preferably sodium hydroxide solution. Use is made in this connection of quaternary p" ammonium compounds and/or phosphonium compounds as the phase-transfer catalysts. For example, benzyltrimethylammonium bromide, S 20 tetramethylammonium bromide, benzyltrimethylammonium chloride, ethltriphenyphosphonium bromide and butylt-riphenylphosphonium chloride may be used; and benzyltrimethylammonium bromide is preferred.

The temperature for the reaction stage amounts to 60°C with a reaction time of approximately 60 minutes. A variation of the phase transfer process is the 25 so-called azeotropic process in which the water that is present and that is formed during the two-phase reaction is distilled off azeotropically under vacuum together 0with the epihaloalkane.

By way of example, the following may be designated as suitable CD/99132022.6 8 epihaloalkanes: 1-chloro-2,3-epoxypropane (epichlorohydrin), 1-chloro-2-methyl- 2,3-epoxypropane and 1-chloro-2,3-epoxvbutane. 1-chloro-2,3-epoxypropane is preferred. Naturally, use can also be made, with success, of still further epihaloalkanes, eg., epibromhydrin.

The acrylate copolymers which contain epoxy groups, have a glass transition temperature of 20°C to 120°C. The preferred glass transition temperature lies in the range from 300C to 90°C. The molecular weights (Mw) generally amount to 1,000 to 30,000, or, preferably, 1,000 to 20,000. The epoxide number of the epoxide-containing acrylate copolymer in accordance with the invention lies in the range from 0.018 to 0.510 or, especially, from 0.035 to 0.412 [equivalents/100g].

Aliphatic polybasic acids, preferably, dibasic acids such as, for example, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, malonic aid, succinic acid, glutracic acid, 1,12-dodecanedioic acid, etc can be used as the hardening agent component The anhydrides of these acids can also be used, eg., glutaric anhydride, succinic anhydride as well as the polyanhydrides of these dicarboxylic acids. These polyanhydrides are obtained via the intermolecular condensation of the designated aliphatic dibasic dicarboxylic acids. Examples are the (poly)anhydride of adipic acid, the (poly)anhydride of azelaic acid, the 20 (poly)anhydride of sebacic acid, the (poly)anhydride of dodecanedioic acid, etc.

The polyanhydrides have a molecular weight (weight average, based on a polystyrene standard) of 1,000 to 5,000. The polyanhydrides can also be modified with a polyol.

o o The polyanhydrides can also be used as hardening agents when in 25 admixture with the aliphatic dibasic dicarboxylic acids or when in admixture with hydroxycarboxylic acids that have melting points between 400C and 150°C, eg., 12-hydroxystearic acid, 2-hydroxyoctadecanoic acid, 3-hydroxyoctadecanoic acid or 10-hydroxyoctadecanoic acid, and 2-hydroxymyristic acid.

Cycloaliphatic dicarboxylic acids such as, for example, 1,4cyclohexanedicarboxylic acid or their polyanhydrides can also be used as CD/9913 2 0 2 2 .6 9 hardening agents.

Suitable hardening agents are also amorphous and semi-crystalline copolyesters. Both the amorphous and the semi-crystalline copolyesters can be prepared in conformity with the condensation processes that are known for polyesters (esterification and/or trans-esterification) in accordance with the prior art. Suitable catalysts such as, for example, dibutyltin oxide or titanium tetrabutylate can also be used if required.

Suitable amorphous carboxy-functional copolyester resins have an acid number of 10 to 200 [mg KOH/g] and a glass transition temperature of Amorphous carboxy-functional copolyesters mainly contain aromatic polybasic carboxylic acids as the acid components such as, for example, terephthalic acid, isophthalic acid, phthalic acid, pyromellitic acid, trimellitic acid, 3,6-dichlorophthalic acid, tetrachlorophthalic acid and, if available, the anhydride[s], chloride[s] or ester[s] thereof. Usually, they contain at least 50 mole-% of terephthalic acid and/or isophthalic acid or, preferably, 80 mole-%. The remainder of the acids (the difference up to 100 mole-%) consists of aliphatic and/or cycloaliphatic polybasic acids such as, for example, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic acid, hexahydroendeomethyleneteraphthalic acid, hexachlorophthalic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, adipic acid, dodecanedicarboxylic 20 acid, succinic acid, maleic acid or dimeric fatty acids, hydroxycarboxylic acids and/or lactones such as, for example, 12-hydroxystearic acid, e-caprolactone or neopentyl glycol hydroxpivalate can also be used. Use is also made, in small quantities, of monocarboxylic acids such as, for example, benzoic acid, tertiary butylbenzoic acid, hexahydrobenzoic acid and saturated aliphatic monocarboxylic 25 acids.

As far as suitable alcohol components are concerned, one may designate the aliphatic diols such as, for example, ethylene glycol, 1,3-propanediol, 1,2propanedion, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,2-dimethylpropane- 1,3-diol (neopentyl glycol), 2,5-hexanedol, 1,6-hexanediol, 2,2-[bis-(4- 30 hydroxycyclohexyl)] propane, 1,4-dimethylolcyclohexane, diethylene glycol, dipropylene glycol and 2,2-bis-[4-(2-hydroxy)]phenyl propane. Polyols are also CD/99132022.6 used in small quantities such as, for example, glycerol, hexanetriol, pentaerythritol, snrhitn!, trimthylolethane trimethvyopropane alnd tris(2-hvdroxy)isocyanurate.

Epoxy compounds can also be used instead of diols or polyols. The proportion of neopentyl glycol and/or propylene glycol in the alcohol component preferably amounts to at least 50 mole-% based on the total acids.

Suitable semi-crystalline polyesters have an acid number of 10 to 400 [mg KOH/g] and an accurately defined DSC melting point. These semi-crystalline polyesters are the condensation products of aliphatic polyols, preferably aliphatic diols, and aliphatic and/or cycloaliphatic and/or aromatic polybasic carboxylic acids, preferably dibasic acids. By way of example, one may designate as the aliphatic polyols: ethylene glycol (1,2-ethanediol), propylene glycol (1,3propanediol), butylene glycol (1,4-butanediol), 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, trimethylolpropane, etc. Aliphatic diols such as, for example, ethylene glycol, butylene glycol or 1,6-hexanediol are preferred.

Suitable polybasic carboxylic acids are aliphatic dicarboxylic acids or, preferably, C4-C20 dicarboxylic acids such as, for example, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, undecanedicarboxylic acid and the aromatic dicarboxylic acids such as, for example, terephthalic acid, isophthalic acid, phthalic acid and their 99 hydrogeneration products such as, for example, 1,4-cyclohexanedicarboxylic acid.

Aliphatic dicarboxylic cids with 6 to 12 carbon atoms are preferred. Naturally, use can also be made of mixtures of various polyols and polybasic carboxylic acids.

Suitable carboxy-functional acrylate polymers have an acid number of 10 to 400 [mg KOH/g].

25 Mixtures of variously suitable hardeners can also be used in the thermosetting powder coating compositions.

Based on the acrylic resin, the quantity of the anhydrides and/or acids that is used as the hardening agent component can vary over a wide range and is governed by the number of epoxide groups in the acrylate resin In general, a molar ratio of carboxy groups or, as the case may be, anhydride groups to CD/99132022.6 11 epoxide groups of 0.4-1.4:1 is selected or, preferably, 0.8-1.2:1.

In the coating system according to the invention, such conventional pigments and/or fillers and/or additives can be present as are commonly used for the preparation and use of powder coatings. These include additives from the group of accelerators, flow-promoting agents and degassing agents, heat stabilizers, UV stabilizers, and/or HALS stabilizers and/or tribo-additives as well as matting agents if required such as, for example, waxes.

The preparation of the powder coatings in accordance with the invention preferably takes place in the melt as a result of the communal extrusion of all the formulation components at temperatures between 600C and 1400C. The extruded material is then cooled, ground and selectively sieved to a grain size that is smaller than 90 lIm. Alternatively, other processes for the preparation of the powder coatings are also suitable such as, for example, mixing together the formulation components in solution, with subsequent precipitation or removal of the solvent by distillation.

S: The application of the powder coatings in accordance with the invention is Socarried out by any process commonly used for such purposes such as, for o example, by means of electrostatic spraying devices (corona or tribo) or using a fluidized bed process.

S 20 Powder coatings prepared as described herein may be applied to substrates such as metal and baked for, 5-60 minutes at 1600 C. to 2200 C.

to form a hard thermoset protective finish which is thermally stable and resistant to oo..

solvents, and which has good metal adhesion properties, good mechanical strength and high durability, against weathering.

.00.

The preparation and the properties of thermosetting powder coating compositions in accordance with the invention are ilustrated below by the following examples.

°00 CD/99132022.6 12 Preparation of Hydroxyl-functional Acrylate Copolymers EXAMPLES 1 AND 2 General procedure: Part I (see Table 1) is introduced into a stainless stell reactor equipped with a stirring device, a cooling device and a heating device together with electronic temperature control. Part I is heated under nitrogen up to the point of refluxing.

Part II and Part III (see Table 1) are then slowly added in parallel over a period of 3 hours, during the course of which the reaction mixture is boiled under reflux.

After addition of Part II and Part III has been terminated, the reaction mixture is boiled for a further 2 hours under reflux. The solvent is then removed from the reaction mixture under vacuum.

TABLE 1 Acrylate Copolymers Containing Hydroxyl Groups (weights are in g) Example 1 Example 2 Resin No. I II Part xylene 1,000.00 1,000.00 Part II ditertiary-butyl 46.25 46.25 peroxide xylene 78.75 78.75 Part III hydroxyethyl 537.43 429.89 methacrylate n-butyl acrylate 185.00 185.00 methyl methacrylate 780.70 888.23 styrene 809.38 809.38 mercaptopropionic 57.90 57.90 acid CD/99132022.6 13 TABLE 2 Properties of Resins I and II Example 1 Example 2 Resin No. I II OH number (mg KOH/g] 98.0 78.0 Tg (calculated) 71 73 Molecular weight (Mw) 7,900 7,800 Preparation of Epoxide-containing Acrylate Copolymers of the Invention EXAMPLE 3 560 g of resin No. I were dissolved in 2,000 g of toluene in a 20 liter reactor that is capable of being heated and that has been equipped with a thermometer, a stirrer and a reflux column. After the addition of 18 ml of boron trifluoride ethyl etherate, the temperature was increased to 80° C. and 100 g of epichlorohydrin were added dropwise over a period of one hour. After this, stirring was continued 10 for 30 minutes at 800 C. and then the mixture was cooled to 50°C. After the addition of 200 g of aqueous caustic soda the mixture was stirred for a further hour at 50°C. After this, the aqueous phase was separated. Resin No. III was obtained (properties: see Table 3) after vacuum distillation of the organic phase at a temperature of 1300C. under reduced pressure (1 mm Hg).

EXAMPLE 4 560 g of resin No. I were dissolved in 2,000 g of toluene and 1,000 g of epichlorohydrin at 600C. in a 20 liter reactor that is capable of being heated and that has been provided with a thermometer, a stirrer and a reflux column. After the addition of 18.6 g of benzyltrimethylammonium chloride, 200 g of aqueous caustic 20 soda were added and the mixture stirred for one hour at 60°C. After this, the aqueous phase was separated. Resin No. IV was obtained (properties: see Table 3) after vacuum distillation of the organic phase at a temperature of 1300C.

CD/99132022.6 14 under reduced pressure (1 mm Hg).

EXAMPLE 700 g of resin No. II were dissolved in 2,000 g of toluene in a 20 liter reactor that is capable of being heated and that has been provided with a thermometer, a stirrer and a reflux column. After the addition of 18 ml of boron trifluoride ethyl etherate, the temperature was increased to 80°C. and 100 g of epichlorohydrin were added dropwise over a period of one hour. After this, stirring was continued for 30 minutes at 800C. and then the mixture was cooled to 50°C. After the addition of 200 g of aqueous caustic soda the mixture was stirred for a further hour at 50°C. After this, the aqueous phase was separated. Resin No. V was obtained (properties: see Table 3) after vacuum distillation of the organic phase at a temperature of 130°C. under reduced pressure (1 mm Hg).

EXAMPLE 6 700 g of resin No. II were dissolved in 2,000 g of toluene and 1,000g of 15 epichlorohydrin at 60°C. in a 20 liter reactor that is capable of being heated and that has been provided with a thermometer, a stirrer and a reflux column. After the addition of 18.6 g of benzyltrimethylammonium chloride, 200 g of aqueous caustic soda were added and the mixture stirred for one hour at 60°C. After this, the aqueous phase was separated. Resin No. VI was obtained (properties: see Table 3) after vacuum distillation of the organic phase at a temperature of 1300C.

under reduced pressure (1 mm Hg).

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0 0 CD/99132022.6 TABLE 3 Properties of Resins III to VI Example 3 Example 4 Example 5 Example 6 Resin No. Ill IV V VI Initial I I II II resin E Number 0.145 0.146 0.117 0.118 [equiv./100 g] Tg 69 70 70 71 (calculated) Molecular 7,900 7,900 7,800 7,800 weight (Mw) mm

S

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mm em me C e mo Preparation of Powder Coatings EXAMPLES 7 AND 8 840 parts by weight of Resin III (example 7) or Resin IV (example 150 parts by weight of dodecanedicarboxylic acid, 5 parts by weight of Resiflow® PV 88 and parts by weight of benzoin were mixed for 30 seconds in the dry state in a Henschel mixer at 700 RPM and then extruded in a Buss-Co-Kneader (PLK 46) extruder using a jacket temperature of 100°C., a cooled screw conveyor and a rate of rotation of the screw of 150 RPM. The extruded material was cooled, ground and selectively sieved to less than 90 lm.

The powder coatings were applied electrostatically to aluminium sheets (Q panel AL-36 5005 H 14/08 (0.8 mm)) and cured at a temperature of 2000C. using a curing time of 15 minutes.

Table 4 shows the technical properties of the resultant lacquers.

EXAMPLES 9 AND 870 parts by weight of Resin V (example 9) or Resin VI (example 10), 120 parts by CD/99132022.6 16 weight of dodecanedicarboxylic acid, 5 parts by weight of Resiflow® PV 88 and narts hib wAinht of hbn7in werei miverl fnr '30 sconnrl in the rldry tate in a Henschel mixer at 700 RPM and then extruded in a Buss-Co-Kneader (PLK 46), extruder using a jacket temperature of 100°C., a cooled screw conveyor and a rate of rotation of the screw of 150 RPM. The extruded material was cooled, ground and selectively sieved to less than 90 im.

The powder coatings were applied electrostatically to aluminium sheets (Q panel AL-36 5005 H 14/08 (0.8 mm)) and cured at a temperature of 200°C. using a curing time of 15 minutes.

Table 4 shows the technical properties of the resultant lacquers.

TABLE 4 Example 7 Example 8 Example 9 Example Resin basis III IV V VI Gelation time 30 31 27 28 Kofler rack 2000C.

Gloss 109 108 108 109 (600 DIN 67530) Flow very good very good very good very good properties Erichsen 9.9 9.8 9.8 9.9 penetration (DIN 53156) (mm) Cross cut 0 0 0 0 (DIN 52151) Impact 30 40 30 (ASTM D 2794, back side) S* 0 4* 6 .4 0 00 9S 0 0g

S

4** *r a. S 0*g* 4. 4 9 4.

0 00* 00~ 6S 0

Claims (12)

1. A thermosetting powder coating composition based on epoxide acrylate copolymers comprising: an acrylate copolymer containing ether bound epoxy groups; an aliphatic and/or cycloaliphatic polybasic acid and/or its anhydride and/or a polyol-modified anhydride of a polybasic acid and/or an amorphous or semi-crystalline carboxy-functional copolyester resin and/or a carboxy-functional acrylate resin; and, optionally, fillers and/or pigments and/or additives, wherein the acrylate copolymer has a molecular weight of 1,000 to 30,000 and a glass transition temperature of 20°C to 120°C and is obtained by reaction of a previously prepared hydroxyl-functional acrylate copolymer with an epihalohy-drin.

2. A thermosetting coating composition in accordance with claim 1, wherein 15 the hydroxyl-functional acrylate copolymer is obtained via copolymerization of a mono-mer mixture comprising: S00•e* 0 to 70 parts by weight of methyl (meth)acrylate; 0 to 60 parts by weight of C2-C18 alkyl or cycloalkyl esters of acrylic acid; 20 0 to 90 parts by weight of vinyl aromatic compounds; 1 to 95 parts by weight of hydroxyl esters of acrylic acid and/or methacrylic acid, wherein the sum of the parts by weight of components through (d) results in 100. CD/99132022.6 18

3. A thermosetting coating composition in accordance with claim 2, wherein *kn^ kl f fl I 4 .nn~nn H a n n fln t r J'f1- I M 1. l> ithe I lyui uAyI-Iu I.o LIoJI acrIi YIlate copolym i III is obtaUJLII In vI UIULUII polymerization or bulk polymerization.

4. A thermosetting coating composition in accordance with claim 1, wherein the hydroxyl-functional acrylate copolymer has an OH number from to 400 [mg KOH/g]. A thermosetting coating composition in accordance with claim 2, wherein the alkyl esters or cycloalkyl esters are selected from the group consisting of ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n- butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert.-butyl acrylate, tert.-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, neopentyl methacrylate, isobornyl o: methacrylate, 3,3,5-trimethyl-cyclohexyl methacrylate, stearyl methacrylate S 15 and mixtures thereof.

6. A thermosetting coating composition in accordance with claim 2, wherein .o the vinyl aromatic compounds are selected from the group consisting of styrene, vinyltoluene and oa-ethylstyrene.

7. A thermosetting coating composition in accordance with claim 2, wherein 20 the hydroxyalkyl esters of acrylic acid and/or methacrylic acid have 2 to 6 carbon atoms in the hydroxyl residue.

8. A thermosetting coating composition in accordance with claim 1, wherein component is a saturated aliphatic polycarboxylic acid with 4 to 12 carbon atoms or a cycloaliphatic dicarboxylic acid with 8 to 15 carbon atoms.

9. A thermosetting coating composition in accordance with claim 1, wherein component is a monomeric, polymeric or polyol-modified anhydride of an aliphatic or a cycloaliphatic dicarboxylic acid. .CD/99132022.6 19 A thermosetting coating composition in accordance with claim 1, wherein component is an amorphous, carboxy-functional copoiyester resin with an acid number from 10 to 200 mg KOH/g and a glass transition temperature of greater than 400C.

11. A thermosetting coating composition in accordance with claim 1, wherein component is a semi-crystalline, carboxy-functional copolyester resin with an acid number from 10 to 400 mg KOH/g.

12. A thermosetting coating composition in accordance with claim 1, wherein component is a carboxy-functional acrylate resin with an acid number from 10 to 400 mg KOH/g.

13. A thermosetting coating composition in accordance with claim 1, wherein component is present in a quantity that corresponds to 0.4 to 1.4 carboxy groups and/or anhy-dride groups per epoxide group in the acrylate copolyester component 15 14. A thermosetting coating composition in accordance with claim 1, wherein the acrylate copolymer has epoxide numbers in the range from 0.018 to 0.510 (equivalents/100g). ST: 15. A coated substrate having one or more protective layers on its surface, each layer comprising an applied coating of a thermosetting powder coating S 20 composition according to claim 1 which has been hardened by the application of heat. *0 o0

16. A coated substrate in accordance with claim 15, wherein said powder coating composition is applied by an electrostatic spraying process or by a fluidized bed process. Ems-lnventa AG By its Registered Patent Attorneys Freehills Patent Attorneys 5 November, 1999