CA2001300C - Powder coating compositions for matt coatings - Google Patents
Powder coating compositions for matt coatingsInfo
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- CA2001300C CA2001300C CA 2001300 CA2001300A CA2001300C CA 2001300 C CA2001300 C CA 2001300C CA 2001300 CA2001300 CA 2001300 CA 2001300 A CA2001300 A CA 2001300A CA 2001300 C CA2001300 C CA 2001300C
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/68—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used
- C08G59/686—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used containing nitrogen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/4007—Curing agents not provided for by the groups C08G59/42 - C08G59/66
- C08G59/4014—Nitrogen containing compounds
- C08G59/4021—Ureas; Thioureas; Guanidines; Dicyandiamides
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/42—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/42—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof
- C08G59/4284—Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof together with other curing agents
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
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- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Paints Or Removers (AREA)
- Epoxy Resins (AREA)
- Polyesters Or Polycarbonates (AREA)
Abstract
Powder coating compositions comprising (a) an epoxy resin, (b) at least one polycarboxylic acid of formula I or II
(see fig I and II) wherein R1, R2, R3 and R4 are each independently of one another a hydrogen atom, C1-C4alkyl or the radical -CH2-CH2-COOH, R5 and R6 are each independently of the other a hydrogen atom, C1-C4alkyl, the radical -CH2-CH2-COOH or, when taken together, are an unsubstituted or alkyl-substituted methylene or polymethylene group, each of 1 to 7 atoms, with the proviso that at least two of the substituents R1 to R6 are the radical -CH2-CH2-COOH, the substituents R are each independently of one another a hydrogen atom or the radical
(see fig I and II) wherein R1, R2, R3 and R4 are each independently of one another a hydrogen atom, C1-C4alkyl or the radical -CH2-CH2-COOH, R5 and R6 are each independently of the other a hydrogen atom, C1-C4alkyl, the radical -CH2-CH2-COOH or, when taken together, are an unsubstituted or alkyl-substituted methylene or polymethylene group, each of 1 to 7 atoms, with the proviso that at least two of the substituents R1 to R6 are the radical -CH2-CH2-COOH, the substituents R are each independently of one another a hydrogen atom or the radical
Description
-I- aoo,3o0 K-17279/=
Powder coating compositions for matt coatings The present invention relates to powder coating compositions based on epoxy resins and a mixture of specific bis-, tris- or tetrakis(S-carboxy-ethyl)cyclohexanones or -cyclopentanones and a carboxyl-terminated saturated polyester, tolyl biguanide or dicyandiamide as curing and matting agent, as well as to the use of said powder coating compositions for producing matt coatings.
Unsubstituted or alkyl-substituted tetrakis(B-carboxyethyl)cyclohexanones and -cyclopentanones are disclosed as curing agents for epoxy resins in GB patent specification 1 033 697. The cured resins are clear and have good mechanical properties.
To produce matt finishes, it is common practice to add matting agents to the powder coating composition. Modifiers which are fraquently added to solvent-containing lacquers, for example silicic acid, talcum, mica, chalk or metal soaps, do not impart the desired matting effect to powder coating compositions. Either the reduction in gloss is insufficient or, if the matting effect is achieved, an impairment of the film-coating properties of the varnish such as adhesion, flexibility, impact strength or resistance to chemicals must be tolerated. For producing coatings with a matt finish it is also known to use powder coating compositions which contain a specific curing agent. For example, mono- or disalts of polycarboxylic acids containing not less than three carboxyl groups and cyclic amidines are disclosed as such curing agents in German Offenle-gungsschrift 2 324 696. It is, however, complicated to prepare these amidine salts, as it is difficult to control the reaction such that exclusively mono- or disalts are formed.
It has now been found that a pronounced reduction in gloss without substantial impairment of the other coating properties is achieved by $001300 using specific mixtures of curing agents based on bis-, tris-or tetra-kis(,Q-carboxyethyl)cyclohexanones or -cycloheptanones or carboxylated polyacetals in epoxy resin powder coating compositions.
Specifically, the present invention relates to a powder coating composition comprising (a) an epoxy resin, (b) at least one polycarboxylic acid of formula I or II
1 o R I~~I Ra R3 ~ ~R4 (1) OR OR
RO CH2 CH CH2-O~ ~O CHZ CH CH20R
CH-X-CH /~ (u)~
RO CH ~~ CH \~CH -O~
2 ( 2)m 2 O CH2 (CH2~ CH20R
n wherein R1, R2, R3 and R4 are each independently of one another a hydrogen atom, C1-C4alkyl or the radical -CH2-CH2-COOH, R5 and R6 are each independently of the other a hydrogen atom, C1-C4alkyl, the radical -CH2-CH2-COOH or, when taken 20 together, are an unsubstituted or alkyl-substituted methylene or polymethylene group, each of 1 to 7 carbon atoms, with the proviso that at least two of the substituents R1 to R6 are - 2a -the radical -CH2-CH2-COON, the substituents R are each independently of one another a hydrogen atom or the radical -CO
HOOC
the ratio of the carboxyl groups present in the 2-carboxy-cyclohexanecarbonyl radical to the RO groups being 0.5 to 1.0, l0 m is an integer from 2 to 5, n is an integer from 0 to 10, and X is a direct bond or an aliphatic or cycloaliphatic radical, and (c) a carboxyl-terminated saturated polyester, tolyl biguanide or dicyandiamide.
The customary epoxy resins suitable for powder coating compositions may be used as component (a). Such compounds are disclosed, for example, in German Offenlegungsschrift 2 838 841. The subject matter of this publi-cation thus falls within the scope of the invention.
The resins employed preferably have an epoxy value of 0.5 to 12 equiva-lents per kg. The preferred epoxy resins are solid at room temperature and, if necessary, may be advanced, for example by reaction with a dihydric phenol.
Preferred epoxy resins are those which contain on average more than one epoxy group in the molecule and which are polyglycidyl derivatives of aromatic or heteroaromatic compounds, especially of aromatic compounds.
particularly preferred resins are non-advanced or advanced polyglycidyl ethers of 2,2-bis(4'-hydroxyphenyl)propane (bisphenol A), 2,2-bis-(3',5'-dibromo-4'-hydroxyphenyl)propane (tetrabromobisphenol A), of bis(4-hydroxyphenyl)methane (bisphenol F) and of novolaks, polyglycidyl derivatives of 4,4'-diaminodiphenylmethane, of 4,4'-diaminodiphenyl-sulfone, and of 2,4,6-trihydroxy-1,3,5-triazine (cyanuric acid), for example triglycidyl isocyanurate.
The polycarboxylic acids of formula I are known compounds. For example, cycloaliphatic polycarboxylic acids of formula I are disclosed in GB patent specification 1 033 697 cited at the outset. Aliphatic polycar-boxylic acids are disclosed, for example, in German Offenlegungs-schrift 2 609 659.
In formula I the substituents R1 to R'' are preferably the carboxyethyl radical and RS and R6, when taken together, are preferably an unsubsti-tuted or an alkyl-substituted polymethylene radical of 2 to 7 carbon atoms, especially an unsubstituted polymethylene radical of 2 to 4 carbon atoms.
Examples of suitable compounds of formula I are 2,2,6,6-tetra(B-carboxy-ethyl)cyclopentanone, 2,2,6,6-tetra(B-carboxyethyl)cyclohexanone, 2,2,4,4-tetra(B-carboxyethyl)pentan-3-one and 1,1,3,3-tetras-carboxy-3 0 ethyl)acetone.
_ 4 _ X00 1300 The compounds of formula II have so far not been described in the literature and can be prepared by reacting compounds of formula III
H H
HO CHZ ~H CHZ-0 CHZ ~H CHZOH
\ ~ ~ / \CH-X-C~-I \ ~ ~ / (III), HO CHz/~\(CHZ)m~\CHZ-0/ CHZ/~\(CHZ)/~\CHZOH
m n wherein X, m and n are as defined for formula II, with hexahydrophthalic anhydride to a compound of formula II. In general, hexahydrophthalic acid is used in this reaction in an amount such that at least half of all HO
groups in the compounds of formula III are converted into 2-carboxycyclo-hexanecarbonyl groups. Preferably not less than 60 % of all hydroxyl groups, more particularly not less than 70 % of all hydroxyl groups, in the compounds of formula III are converted into 2-carboxycyclohexane-carbonyl groups.
The compounds of formula II, which have been developed specially for the preparation of the powder coating compositions of this invention, thus likewise fall within the scope of this invention.
In formula II, X is preferably a direct bond or an aliphatic or cycloali-phatic radical which contains up to 20 carbon atoms. Most preferably, X
is a direct bond or an aliphatic radical of up to 12 carbon atoms.
Further, m is preferably 2 or 3 and n is preferably 0 or a value from 0.1 to 3.
Compounds of formula III, wherein n is 1 or a number greater than 1, are known and can be prepared in known manner, for example by the process disclosed in US patent specification 4 374 953 by polycondensing a polyol of formula IV
H
HO-CH 2\ /~H \ CH Z-OH
/ (IV), HO-CHZ/~\(CHZ)/~\CHZ-OH
m wherein m has the same meaning as given for formula II or III, with an aliphatic or cycloaliphatic dialdehyde or with an aliphatic or cycloali-phatic diketone to a hydroxylated polycycloacetal or polycycloketal of formula III.
Examples of suitable polyols of formula IV are the aforementioned polyols of formula III, wherein n is 0. Dialdehydes or diketones which may be suitably employed for carrying out the process are, for example, glyoxal, glutaryl aldehyde, succinaldehyde and 1,4-cyclohexanedione.
The polycondensation of the polyol of formula IV with the dialdehyde or diketone to the hydroxylated polycycloacetal of formula III is prefer-ably carried out in an inert organic solvent such as toluene, with an acid catalyst, for example in the presence of H3P02, while simultane-ously removing water from the reaction mixture.
In the curable mixtures of this invention it is further preferred to use as compounds of formula II those which have a softenting temperature in the range from 60 to 180°C, preferably from 80 to 140°C.
Carboxyl-terminated saturated polyesters suitable for use as compo-nent (c) preferably contain on average more than two carboxyl groups per molecule, and have an acid number from 15 to 100 and an average molecular weight from 500 to 10 000. The polyesters are preferably solid at room temperature and have a glass transition temperature in the range from 40 to 80°C.
Such polyesters are disclosed, for example, in US patent specification 3 397 254 and in German Offenlegungsschrift 2 163 962. They can be obtaind, for example, by reacting hydroxyl-terminated polyesters with tricarboxylic anhydrides or tetracarboxylic dianhydrides. The hydroxyl-terminated polyesters are in turn reaction products of polyols with dicarboxylic acids or dicarboxylic anhydrides and conveniently have an average degree of polymerisation of not less than 3, in general from 3 to 25, preferably from 5 to 12.
~A01300 Examples of suitable polyols are ethylene glycol, glycerol, 1,4-butane-diol, neopentanediol and cyclohexanediol.
Examples of suitable dicarboxylic acids are isophthalic acid, tereph-thalic acid, cyclohexanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid or sebacic acid.
Examples of suitable tricarboxylic anhydrides are anhydrides of ali-phatic tricarboxylic acids such as tricarballylic acid (1,2,3-propane-tricarboxylic acid), of aromatic tricarboxylic acids such as trimellitic acid (benzene-1,2,4-tricarboxylic acid) and hemimellitic acid (benzene-1,2,3-tricarboxylic acid), or of cycloaliphatic tricarboxylic acids such as 6-methylcyclohex-4-ene-1,2,3-tricarboxylic acid. Examples of suitable tetracarboxylic dianhydrides are pyromellitic dianhydride or benzo-phenone-3,3',4,4'-tetracarboxylic dianhydride.
Tolyl biguanide and dicyandiamide, which may also be used as compo-nent (c) in the powder coating composition of this invention, are known and commercially available.
Where component (c) is a carboxyl-terminated saturated polyester, said polyester will be used together with a polycarboxylic acid of formula I
or II, with respect to the resin (a), conveniently in about stoichio-metric proportion, i.e. the ratio of the sum of the carboxyl equivalents per epoxy equivalent is from 0.5 to 1.5, preferably from 0.7 to 1.3 and, most preferably, from 0.8 to 1.2. In the powder coating composition of this invention, the ratio of a polycarboxylic acid of formula I or II to the carboxyl-terminated saturated polyester may be from 1:10 to 10:1. The powder coating composition of this invention will preferably contain the polycarboxylic acid of formula I or II and the carboxyl-terminated saturated polyester in a ratio of 1:5 to 5:1, most preferably of 1:3 to 3:1.
Where component (c) is tolyl biguanide or dicyandiamide, the proportion of a polycarboxylic acid of formula I or II in the powder coating composition of this invention will generally be only 10 to 90 equivalent ~p0130p _,_ percent, preferably 20 to 80 equivalent percent, most preferably 40 to 60 equivalent percent, of the stoichiometric amount necessary for a complete cure of the epoxy resin. The proportion of dicyandiamide or tolyl biguanide still necessary for a complete cure of the epoxy resin can then be calculated, for the person skilled in the art of epoxy resin formula-tions knows the amount of dicyandiamide or tolyl biguanamide necessary to cure an epoxy resin. In general, the amount of these curing agents is in the order of 5 to 30 percent by weight per 100 parts of the epoxy resin.
If desired, accelerators may be added to the powder coating compositions.
In addition to tert-amines, Mannich bases and quaternary ammonium bases, suitable accelerators are nitrogen-containing heterocycles such as pyrazoles, imidazoles, pyrroles, pyridines, pyrazines, indoles and piperidines. Preferred heterocycles are those having at least one tertiary nitrogen atom in the ring, including N-substituted pyrroles such as N-methylpyrrole, N-substituted pyridines such as N-methyl-, N-ethyl-and N-benzylpyridines, N-substituted pyrazines such as N,N'-dimethyl-and N,N'-diethylpyrazines, N-substituted indoles such as N-methyl- and N-ethylindoles, N-substituted piperidines such as N-methyl-, N-ethyl-and N-isopropylpiperidines and, preferably, imidazoles such as imida-zole itself, N-substituted imidazoles such as 1-methylimidazole and 1-(2',4'-diamino-s-triazin-6'-ylethyl)-2-methylimidazole, (6-[2-(2-methyl-1H-imidazol-1-yl)ethyl-1,3,3-triazine-2,4-diamine) and C-substi-tuted imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-n-propyl-imidazole, 4-methylimidazole, 2-methyl-4-phenylimidazole, 2-phenylimida-zole, 2-ethyl-4-methylimidazole and benzimidazole.
Particularly preferred accelerator are N,N-dimethyl-1,3-propanediamine, 2,4,6-tris(dimethylaminomethyl)phenol, N,N,N',N'-tetramethylethylene-diamine, triethylamine, benzyldimethylamine, 2-methylimidazole and 2-ethyl-4-methylimidazole.
If desired, further modifiers conventionally employed in the coating industry, for example light stabilisers, dyes and, in particular, deaerating agents, flow control agents and/or pigments, preferably TiOz may be added to the powder coating compositions.
_ a _ X001300 Examples of flow control agents are: polyvinyl acetals such as polyvinyl butyral ("Movital" B 30 H~, supplied by Hoechst), polyethylene glycol, polyvinyl pyrrolidone, glycerol, acrylic copolymers such as "Modaflow"~
or "Acrylron" MFP~, supplied by MONSANTO and PROTEX respectively.
The preferred dearating agent is benzoin.
The novel powder coating compositions may be prepared by simply mixing the components, for example in a ball mill. Another possible method of preparation consists in melting the components together, preferably in an extruder, for example in a Buss Kokneader~ and then comminuting the cooled melt. The compositions preferably have a particle size in the range from 0.015 to 500 um, most preferably from 10 to 75 um.
Matt coatings are prepared by curing the powder coating compositions.
This is done by applying the powder coating composition to the substrate to be coated and heating to a temperature of not less than 120°C, preferably in the range from 150° to 250°C, to cure the resin.
A further object of the invention is the use of the powder coating compositions of the invention for obtaining matt coatings on surfaces, especially on metals such as aluminium or steel.
To prepare the powder coating compositions of this invention, a number of 2 0 components are synthesised and formulated as follows:
2,2,5,5-Tetra(S-carboxyethyl)cyclopentanone With stirring, 633 g of acrylonitrile are added dropwise at 20°C to 250 g of cyclopentanone and 38 g of 40 % aqueous KOH in 920 ml of tert-butyl alcohol. During this addition a precipitate forms and, when addition is complete, the resultant dense slurry is stirred for 1 hour and then filtered. The filter residue is washed with 400 ml of ice-water, to give 725 g of 2,2,5,5-tetra(s-cyanoethyl)cyclopentanone with a melting point of 157-159°C.
*Trade-mark Elemental analysis for Cl~HZON40:
theory: C = 68.90 % H = 6.80 % N = 18.90 found: C = 68.83 % H = 6.94 % N = 18.00 466 g of the above nitrile and 442 g of KOH are heated for 6 hours to 95°C and then the pH is adjusted to 1 with 786 g of concentrated (37 %) hydrochloric acid at room temperature, whereupon a precipitate forms.
This precipitate is isolated by filtration and washed with 400 ml of ice-water, to give 464 g of 2,2,5,5-tetra(S-carboxyethyl)cyclopentanone with a melting point of 152-155°C.
Elemental analysis for Cl~Hz409:
theory: C = 54.83 % H = 6.50 found: C = 55.53 % H = 6.65 Content of COON groups; theory: 10.74 equivalents/kg, found: 10.78 equivalents/kg.
2,2,4,4-Tetra(S-carboxyethyl)pentanone The above described procedure for preparing 2,2,5,5-tetras-carboxy-ethyl)cyclopentanone is repeated, using pentan-3-one in place of cyclo-pentanone, to give 2,2,4,4-tetra(S-carboxyethyl)pentanone With a melting point of 176-178°C.
Elemental analysis for Cl~Hz609:
theory: C = 54.49 % H = 6.94 found: C = 54.22 % H = 7.02 content of COOH-groups, theory: 10.68 equivalents/kg found: 10.54 equivalents/kg 2,2,6,6-Tetra(S-carboxyethyl)cyclohexanone The procedure for preparing 2,2,5,5-tetra(S-carboxyethyl)cyclopentanone is repeated, using cyclohexanone in place of cyclopentanone, to give 2,2,6,6-tetra(s-carboxyethyl)cyclohexanone with a melting point of 174-176°C.
Elemental analysis for C18HZ609:
theory: C = 55.95 % H = 6.78 found: C = 55.59 % H = 6.75 content of COOH, theory: 10.35 equivalents/kg, found: 10.44 equivalents/kg.
Carboxylated polyacetal I
a) 551 g of 2,2,6,6-tetramethylolcyclohexan-1-of and 1,9 g hypophos-phorous acid are suspended in 2000 ml toluene at 100°C. Then 455 ml of a 50 % aqueous solution of glutardialdehyde are added dropwise over 50 minutes. By lowering the pressure to ca. 0.15 bar, distillation of water through a water separator commences. When the removal of water is complete, the reaction mixture is heated under reflux for a further 2 hours under a pressure of 1.0 bar. The reaction mixture is then cooled to 30°C, the toluene phase is removed by decantation, and the resultant product is dissolved in 350 ml of methanol. The methanol is removed by rotary evaporation and the residue is dried at 120°C/0.02 bar.
Yield: 640 g (93 % of theory, n = 5.7).
Softening point: 147°C
Mn (gel permeation chromatography in THF): 1839, Mw/Mn = 3.65 Hydroxyl content: 5.47 eq./kg.
b) 50 g of the hydroxylated polyacetal prepared according to a) are suspended at 107°C in 120 ml of methyl isobutyl acetone. Then 34 g of hexahydrophthalic anhydride are added over the course of 2 hours. The reaction mixture is heated for a further 3 hours. 'The solvent is removed by distillation in a rotary evaporator and the -residue is dried at 90°C/0.02 bar.
Yield: 75 g (90 % of theory) Softening point: 125°C
Mn (gel permeation chromatography in THF): 1636, Mw/Mn = 3.44 Carboxyl content: 2.86 eq./kg.
Accelerator A
A mixture of 87.5 parts of a carboxyl-terminated saturated solid poly-ester resin and 12.5 parts of tetradecyltrimethylammonium bromide.
._ ~~01300 Example 1: The following components are homogenised at a temperature of 80°C in an extruder (Ko-kneader***, supplied by Busa, Pratteln, Switzerland):
817.6 g of a bisphenol A diglycidyl ether with a softening point (accor-ding to DIN 51 920) of 86°C and an epoxy value of 1.3 equiva-lents/kg, 5.0 g of Acrylron~ MFP (butylated polyacrylate, supplied by Protex) as flow control agent, 82.3 g of Crylcoat~ 314 (carboxyl-terminated saturated polyester with an acid number of 73 equivalents of KOH/kg and a glass transition temperature (Tg) of 60°C (DSC), supplied by UCB, Belgium), 95.1 g of 2,2,5,5-tetra(S-carboxyethyl)cyclopentanone, 2.0 g of benzoin, 500.0 g of TiOz, and 20.0 g of accelerator A.
The extrudate i~ ground by known standard procedures to a particle size of ca. 40 um and sprayed with an electrostatic gun on to an aluminium sheet. Stowing for 30 minutes at 200°C gives a varnish film having the following properties:
2 0 film thickness (ym) - 61 Erichsen deep drawing test according to DIN 53 156 (mm) = 9.3 *) impact resistance (cm~kg) = 80 gloss (~ 60°) (%) - 0 yellowness index according to DIN 6167 - 2.8 flow at 200°C~) - good/very good.
) A force of known weight is dropped from a specific height on to the back of the coated aluminium sheet. The value obtained, height (cm) x weight (kg), indicates the greatest impact at which the film 3 0 still remains intact.
***Trade-mark ) Test method in which the flow of the coating is determined visually as moderate, good or very good.
Example 2: A powder coating composition is prepared by mixing the following components in exactly the same manner as in Example 1:
762.5 g of the bisphenol A diglydidyl ether according to Example 1, 5.0 g of Acrylron~ MFP, 153.5 g of Crylcoat~ 314, 79.0 g of 2,2,5,5-tetra(B-carboxyethyl)cyclopentanone, 2.0 g of benzoin, 500.0 g of Ti02, and 20.0 g of curing accelerator A.
After stowing for 30 minutes at 200°C, the film has the following properties:
film thickness (um) - 54 Erichsen deep drawing test (mm) - 8.8 impact resistance (cm~kg) = 80 gloss ( ~( 60° ) (%) _ 4 yellowness index (DIN 6167) - 3.1 flow at 250°C = very good.
Example 3: A powder coating composition is prepared by mixing the following components in exactly the same manner as in Example 1:
931.0 g of the bisphenol A diglycidyl ether according to Example l, 5.0 g of Acrylron~ MFP, 30.1 g of 2,2,5,5-tetra(B-carboxyethyl)cyclopentanone, 37.7 g of tolyl biguanide, 2.0 g of benzoin, and 500.0 g of TiOz.
After stowing for 30 minutes at 200°C, the varnish film has the following properties:
film thickness (um) - 56 Erichsen deep drawing test (mm) - 9.5 impact resistance (cm~kg) = 160 gloss (~( 60°) (%) - 4 yellowness index (DIN 6167) - 3.5 flow at 200°C - good/moderate.
Example 4: A powder coating composition is prepared by mixing the following components in exactly the same manner as in Example 1:
876.0 g of the bisphenol A diglycidyl ether according to Example 1, 5.0 g of Acrylron~ MFP, 92.0 g of carboxyl-terminated polyacetal I, 32.0 g of tolyl biguanide, 2.0 g of benzoin, and 500.0 g of TiOz.
After stowing for 30 minutes at 200°C, the film has the following properties:
film thickness (um) - 66 Erichsen deep drawing test (mm) - 10 impact resistance (cm~kg) = 40 gloss (~ 60°) (%) - 15 yellowness index (DIN 6167) - 6.7 flow at 200°C - very good.
Example 5: A powder coating composition is prepared by mixing the following components in exactly the same manner as in Example 1:
730.0 g of the bisphenol A diglycidyl ether according to Example 1, 5.0 g of Acrylron~ MFP, 27.0 g of tolyl biguanide, 23.0 g of 2,2,4,4-tetra(B-carboxylethyl)pentan-3-one, 2.0 g of benzoin, and 390.0 g of TiOZ.
After stowing for 30 minutes at 200°C, the film has the following properties:
film thickness (um) - 54 Erichsen deep drawing test (mm) - 9.3 impact resistance (cm~kg) = 160 gloss (~( 60°) (~) - 28 yellowness index (DIN 6167) - 4~2 flow at 200°C - good/moderate.
Powder coating compositions for matt coatings The present invention relates to powder coating compositions based on epoxy resins and a mixture of specific bis-, tris- or tetrakis(S-carboxy-ethyl)cyclohexanones or -cyclopentanones and a carboxyl-terminated saturated polyester, tolyl biguanide or dicyandiamide as curing and matting agent, as well as to the use of said powder coating compositions for producing matt coatings.
Unsubstituted or alkyl-substituted tetrakis(B-carboxyethyl)cyclohexanones and -cyclopentanones are disclosed as curing agents for epoxy resins in GB patent specification 1 033 697. The cured resins are clear and have good mechanical properties.
To produce matt finishes, it is common practice to add matting agents to the powder coating composition. Modifiers which are fraquently added to solvent-containing lacquers, for example silicic acid, talcum, mica, chalk or metal soaps, do not impart the desired matting effect to powder coating compositions. Either the reduction in gloss is insufficient or, if the matting effect is achieved, an impairment of the film-coating properties of the varnish such as adhesion, flexibility, impact strength or resistance to chemicals must be tolerated. For producing coatings with a matt finish it is also known to use powder coating compositions which contain a specific curing agent. For example, mono- or disalts of polycarboxylic acids containing not less than three carboxyl groups and cyclic amidines are disclosed as such curing agents in German Offenle-gungsschrift 2 324 696. It is, however, complicated to prepare these amidine salts, as it is difficult to control the reaction such that exclusively mono- or disalts are formed.
It has now been found that a pronounced reduction in gloss without substantial impairment of the other coating properties is achieved by $001300 using specific mixtures of curing agents based on bis-, tris-or tetra-kis(,Q-carboxyethyl)cyclohexanones or -cycloheptanones or carboxylated polyacetals in epoxy resin powder coating compositions.
Specifically, the present invention relates to a powder coating composition comprising (a) an epoxy resin, (b) at least one polycarboxylic acid of formula I or II
1 o R I~~I Ra R3 ~ ~R4 (1) OR OR
RO CH2 CH CH2-O~ ~O CHZ CH CH20R
CH-X-CH /~ (u)~
RO CH ~~ CH \~CH -O~
2 ( 2)m 2 O CH2 (CH2~ CH20R
n wherein R1, R2, R3 and R4 are each independently of one another a hydrogen atom, C1-C4alkyl or the radical -CH2-CH2-COOH, R5 and R6 are each independently of the other a hydrogen atom, C1-C4alkyl, the radical -CH2-CH2-COOH or, when taken 20 together, are an unsubstituted or alkyl-substituted methylene or polymethylene group, each of 1 to 7 carbon atoms, with the proviso that at least two of the substituents R1 to R6 are - 2a -the radical -CH2-CH2-COON, the substituents R are each independently of one another a hydrogen atom or the radical -CO
HOOC
the ratio of the carboxyl groups present in the 2-carboxy-cyclohexanecarbonyl radical to the RO groups being 0.5 to 1.0, l0 m is an integer from 2 to 5, n is an integer from 0 to 10, and X is a direct bond or an aliphatic or cycloaliphatic radical, and (c) a carboxyl-terminated saturated polyester, tolyl biguanide or dicyandiamide.
The customary epoxy resins suitable for powder coating compositions may be used as component (a). Such compounds are disclosed, for example, in German Offenlegungsschrift 2 838 841. The subject matter of this publi-cation thus falls within the scope of the invention.
The resins employed preferably have an epoxy value of 0.5 to 12 equiva-lents per kg. The preferred epoxy resins are solid at room temperature and, if necessary, may be advanced, for example by reaction with a dihydric phenol.
Preferred epoxy resins are those which contain on average more than one epoxy group in the molecule and which are polyglycidyl derivatives of aromatic or heteroaromatic compounds, especially of aromatic compounds.
particularly preferred resins are non-advanced or advanced polyglycidyl ethers of 2,2-bis(4'-hydroxyphenyl)propane (bisphenol A), 2,2-bis-(3',5'-dibromo-4'-hydroxyphenyl)propane (tetrabromobisphenol A), of bis(4-hydroxyphenyl)methane (bisphenol F) and of novolaks, polyglycidyl derivatives of 4,4'-diaminodiphenylmethane, of 4,4'-diaminodiphenyl-sulfone, and of 2,4,6-trihydroxy-1,3,5-triazine (cyanuric acid), for example triglycidyl isocyanurate.
The polycarboxylic acids of formula I are known compounds. For example, cycloaliphatic polycarboxylic acids of formula I are disclosed in GB patent specification 1 033 697 cited at the outset. Aliphatic polycar-boxylic acids are disclosed, for example, in German Offenlegungs-schrift 2 609 659.
In formula I the substituents R1 to R'' are preferably the carboxyethyl radical and RS and R6, when taken together, are preferably an unsubsti-tuted or an alkyl-substituted polymethylene radical of 2 to 7 carbon atoms, especially an unsubstituted polymethylene radical of 2 to 4 carbon atoms.
Examples of suitable compounds of formula I are 2,2,6,6-tetra(B-carboxy-ethyl)cyclopentanone, 2,2,6,6-tetra(B-carboxyethyl)cyclohexanone, 2,2,4,4-tetra(B-carboxyethyl)pentan-3-one and 1,1,3,3-tetras-carboxy-3 0 ethyl)acetone.
_ 4 _ X00 1300 The compounds of formula II have so far not been described in the literature and can be prepared by reacting compounds of formula III
H H
HO CHZ ~H CHZ-0 CHZ ~H CHZOH
\ ~ ~ / \CH-X-C~-I \ ~ ~ / (III), HO CHz/~\(CHZ)m~\CHZ-0/ CHZ/~\(CHZ)/~\CHZOH
m n wherein X, m and n are as defined for formula II, with hexahydrophthalic anhydride to a compound of formula II. In general, hexahydrophthalic acid is used in this reaction in an amount such that at least half of all HO
groups in the compounds of formula III are converted into 2-carboxycyclo-hexanecarbonyl groups. Preferably not less than 60 % of all hydroxyl groups, more particularly not less than 70 % of all hydroxyl groups, in the compounds of formula III are converted into 2-carboxycyclohexane-carbonyl groups.
The compounds of formula II, which have been developed specially for the preparation of the powder coating compositions of this invention, thus likewise fall within the scope of this invention.
In formula II, X is preferably a direct bond or an aliphatic or cycloali-phatic radical which contains up to 20 carbon atoms. Most preferably, X
is a direct bond or an aliphatic radical of up to 12 carbon atoms.
Further, m is preferably 2 or 3 and n is preferably 0 or a value from 0.1 to 3.
Compounds of formula III, wherein n is 1 or a number greater than 1, are known and can be prepared in known manner, for example by the process disclosed in US patent specification 4 374 953 by polycondensing a polyol of formula IV
H
HO-CH 2\ /~H \ CH Z-OH
/ (IV), HO-CHZ/~\(CHZ)/~\CHZ-OH
m wherein m has the same meaning as given for formula II or III, with an aliphatic or cycloaliphatic dialdehyde or with an aliphatic or cycloali-phatic diketone to a hydroxylated polycycloacetal or polycycloketal of formula III.
Examples of suitable polyols of formula IV are the aforementioned polyols of formula III, wherein n is 0. Dialdehydes or diketones which may be suitably employed for carrying out the process are, for example, glyoxal, glutaryl aldehyde, succinaldehyde and 1,4-cyclohexanedione.
The polycondensation of the polyol of formula IV with the dialdehyde or diketone to the hydroxylated polycycloacetal of formula III is prefer-ably carried out in an inert organic solvent such as toluene, with an acid catalyst, for example in the presence of H3P02, while simultane-ously removing water from the reaction mixture.
In the curable mixtures of this invention it is further preferred to use as compounds of formula II those which have a softenting temperature in the range from 60 to 180°C, preferably from 80 to 140°C.
Carboxyl-terminated saturated polyesters suitable for use as compo-nent (c) preferably contain on average more than two carboxyl groups per molecule, and have an acid number from 15 to 100 and an average molecular weight from 500 to 10 000. The polyesters are preferably solid at room temperature and have a glass transition temperature in the range from 40 to 80°C.
Such polyesters are disclosed, for example, in US patent specification 3 397 254 and in German Offenlegungsschrift 2 163 962. They can be obtaind, for example, by reacting hydroxyl-terminated polyesters with tricarboxylic anhydrides or tetracarboxylic dianhydrides. The hydroxyl-terminated polyesters are in turn reaction products of polyols with dicarboxylic acids or dicarboxylic anhydrides and conveniently have an average degree of polymerisation of not less than 3, in general from 3 to 25, preferably from 5 to 12.
~A01300 Examples of suitable polyols are ethylene glycol, glycerol, 1,4-butane-diol, neopentanediol and cyclohexanediol.
Examples of suitable dicarboxylic acids are isophthalic acid, tereph-thalic acid, cyclohexanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid or sebacic acid.
Examples of suitable tricarboxylic anhydrides are anhydrides of ali-phatic tricarboxylic acids such as tricarballylic acid (1,2,3-propane-tricarboxylic acid), of aromatic tricarboxylic acids such as trimellitic acid (benzene-1,2,4-tricarboxylic acid) and hemimellitic acid (benzene-1,2,3-tricarboxylic acid), or of cycloaliphatic tricarboxylic acids such as 6-methylcyclohex-4-ene-1,2,3-tricarboxylic acid. Examples of suitable tetracarboxylic dianhydrides are pyromellitic dianhydride or benzo-phenone-3,3',4,4'-tetracarboxylic dianhydride.
Tolyl biguanide and dicyandiamide, which may also be used as compo-nent (c) in the powder coating composition of this invention, are known and commercially available.
Where component (c) is a carboxyl-terminated saturated polyester, said polyester will be used together with a polycarboxylic acid of formula I
or II, with respect to the resin (a), conveniently in about stoichio-metric proportion, i.e. the ratio of the sum of the carboxyl equivalents per epoxy equivalent is from 0.5 to 1.5, preferably from 0.7 to 1.3 and, most preferably, from 0.8 to 1.2. In the powder coating composition of this invention, the ratio of a polycarboxylic acid of formula I or II to the carboxyl-terminated saturated polyester may be from 1:10 to 10:1. The powder coating composition of this invention will preferably contain the polycarboxylic acid of formula I or II and the carboxyl-terminated saturated polyester in a ratio of 1:5 to 5:1, most preferably of 1:3 to 3:1.
Where component (c) is tolyl biguanide or dicyandiamide, the proportion of a polycarboxylic acid of formula I or II in the powder coating composition of this invention will generally be only 10 to 90 equivalent ~p0130p _,_ percent, preferably 20 to 80 equivalent percent, most preferably 40 to 60 equivalent percent, of the stoichiometric amount necessary for a complete cure of the epoxy resin. The proportion of dicyandiamide or tolyl biguanide still necessary for a complete cure of the epoxy resin can then be calculated, for the person skilled in the art of epoxy resin formula-tions knows the amount of dicyandiamide or tolyl biguanamide necessary to cure an epoxy resin. In general, the amount of these curing agents is in the order of 5 to 30 percent by weight per 100 parts of the epoxy resin.
If desired, accelerators may be added to the powder coating compositions.
In addition to tert-amines, Mannich bases and quaternary ammonium bases, suitable accelerators are nitrogen-containing heterocycles such as pyrazoles, imidazoles, pyrroles, pyridines, pyrazines, indoles and piperidines. Preferred heterocycles are those having at least one tertiary nitrogen atom in the ring, including N-substituted pyrroles such as N-methylpyrrole, N-substituted pyridines such as N-methyl-, N-ethyl-and N-benzylpyridines, N-substituted pyrazines such as N,N'-dimethyl-and N,N'-diethylpyrazines, N-substituted indoles such as N-methyl- and N-ethylindoles, N-substituted piperidines such as N-methyl-, N-ethyl-and N-isopropylpiperidines and, preferably, imidazoles such as imida-zole itself, N-substituted imidazoles such as 1-methylimidazole and 1-(2',4'-diamino-s-triazin-6'-ylethyl)-2-methylimidazole, (6-[2-(2-methyl-1H-imidazol-1-yl)ethyl-1,3,3-triazine-2,4-diamine) and C-substi-tuted imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-n-propyl-imidazole, 4-methylimidazole, 2-methyl-4-phenylimidazole, 2-phenylimida-zole, 2-ethyl-4-methylimidazole and benzimidazole.
Particularly preferred accelerator are N,N-dimethyl-1,3-propanediamine, 2,4,6-tris(dimethylaminomethyl)phenol, N,N,N',N'-tetramethylethylene-diamine, triethylamine, benzyldimethylamine, 2-methylimidazole and 2-ethyl-4-methylimidazole.
If desired, further modifiers conventionally employed in the coating industry, for example light stabilisers, dyes and, in particular, deaerating agents, flow control agents and/or pigments, preferably TiOz may be added to the powder coating compositions.
_ a _ X001300 Examples of flow control agents are: polyvinyl acetals such as polyvinyl butyral ("Movital" B 30 H~, supplied by Hoechst), polyethylene glycol, polyvinyl pyrrolidone, glycerol, acrylic copolymers such as "Modaflow"~
or "Acrylron" MFP~, supplied by MONSANTO and PROTEX respectively.
The preferred dearating agent is benzoin.
The novel powder coating compositions may be prepared by simply mixing the components, for example in a ball mill. Another possible method of preparation consists in melting the components together, preferably in an extruder, for example in a Buss Kokneader~ and then comminuting the cooled melt. The compositions preferably have a particle size in the range from 0.015 to 500 um, most preferably from 10 to 75 um.
Matt coatings are prepared by curing the powder coating compositions.
This is done by applying the powder coating composition to the substrate to be coated and heating to a temperature of not less than 120°C, preferably in the range from 150° to 250°C, to cure the resin.
A further object of the invention is the use of the powder coating compositions of the invention for obtaining matt coatings on surfaces, especially on metals such as aluminium or steel.
To prepare the powder coating compositions of this invention, a number of 2 0 components are synthesised and formulated as follows:
2,2,5,5-Tetra(S-carboxyethyl)cyclopentanone With stirring, 633 g of acrylonitrile are added dropwise at 20°C to 250 g of cyclopentanone and 38 g of 40 % aqueous KOH in 920 ml of tert-butyl alcohol. During this addition a precipitate forms and, when addition is complete, the resultant dense slurry is stirred for 1 hour and then filtered. The filter residue is washed with 400 ml of ice-water, to give 725 g of 2,2,5,5-tetra(s-cyanoethyl)cyclopentanone with a melting point of 157-159°C.
*Trade-mark Elemental analysis for Cl~HZON40:
theory: C = 68.90 % H = 6.80 % N = 18.90 found: C = 68.83 % H = 6.94 % N = 18.00 466 g of the above nitrile and 442 g of KOH are heated for 6 hours to 95°C and then the pH is adjusted to 1 with 786 g of concentrated (37 %) hydrochloric acid at room temperature, whereupon a precipitate forms.
This precipitate is isolated by filtration and washed with 400 ml of ice-water, to give 464 g of 2,2,5,5-tetra(S-carboxyethyl)cyclopentanone with a melting point of 152-155°C.
Elemental analysis for Cl~Hz409:
theory: C = 54.83 % H = 6.50 found: C = 55.53 % H = 6.65 Content of COON groups; theory: 10.74 equivalents/kg, found: 10.78 equivalents/kg.
2,2,4,4-Tetra(S-carboxyethyl)pentanone The above described procedure for preparing 2,2,5,5-tetras-carboxy-ethyl)cyclopentanone is repeated, using pentan-3-one in place of cyclo-pentanone, to give 2,2,4,4-tetra(S-carboxyethyl)pentanone With a melting point of 176-178°C.
Elemental analysis for Cl~Hz609:
theory: C = 54.49 % H = 6.94 found: C = 54.22 % H = 7.02 content of COOH-groups, theory: 10.68 equivalents/kg found: 10.54 equivalents/kg 2,2,6,6-Tetra(S-carboxyethyl)cyclohexanone The procedure for preparing 2,2,5,5-tetra(S-carboxyethyl)cyclopentanone is repeated, using cyclohexanone in place of cyclopentanone, to give 2,2,6,6-tetra(s-carboxyethyl)cyclohexanone with a melting point of 174-176°C.
Elemental analysis for C18HZ609:
theory: C = 55.95 % H = 6.78 found: C = 55.59 % H = 6.75 content of COOH, theory: 10.35 equivalents/kg, found: 10.44 equivalents/kg.
Carboxylated polyacetal I
a) 551 g of 2,2,6,6-tetramethylolcyclohexan-1-of and 1,9 g hypophos-phorous acid are suspended in 2000 ml toluene at 100°C. Then 455 ml of a 50 % aqueous solution of glutardialdehyde are added dropwise over 50 minutes. By lowering the pressure to ca. 0.15 bar, distillation of water through a water separator commences. When the removal of water is complete, the reaction mixture is heated under reflux for a further 2 hours under a pressure of 1.0 bar. The reaction mixture is then cooled to 30°C, the toluene phase is removed by decantation, and the resultant product is dissolved in 350 ml of methanol. The methanol is removed by rotary evaporation and the residue is dried at 120°C/0.02 bar.
Yield: 640 g (93 % of theory, n = 5.7).
Softening point: 147°C
Mn (gel permeation chromatography in THF): 1839, Mw/Mn = 3.65 Hydroxyl content: 5.47 eq./kg.
b) 50 g of the hydroxylated polyacetal prepared according to a) are suspended at 107°C in 120 ml of methyl isobutyl acetone. Then 34 g of hexahydrophthalic anhydride are added over the course of 2 hours. The reaction mixture is heated for a further 3 hours. 'The solvent is removed by distillation in a rotary evaporator and the -residue is dried at 90°C/0.02 bar.
Yield: 75 g (90 % of theory) Softening point: 125°C
Mn (gel permeation chromatography in THF): 1636, Mw/Mn = 3.44 Carboxyl content: 2.86 eq./kg.
Accelerator A
A mixture of 87.5 parts of a carboxyl-terminated saturated solid poly-ester resin and 12.5 parts of tetradecyltrimethylammonium bromide.
._ ~~01300 Example 1: The following components are homogenised at a temperature of 80°C in an extruder (Ko-kneader***, supplied by Busa, Pratteln, Switzerland):
817.6 g of a bisphenol A diglycidyl ether with a softening point (accor-ding to DIN 51 920) of 86°C and an epoxy value of 1.3 equiva-lents/kg, 5.0 g of Acrylron~ MFP (butylated polyacrylate, supplied by Protex) as flow control agent, 82.3 g of Crylcoat~ 314 (carboxyl-terminated saturated polyester with an acid number of 73 equivalents of KOH/kg and a glass transition temperature (Tg) of 60°C (DSC), supplied by UCB, Belgium), 95.1 g of 2,2,5,5-tetra(S-carboxyethyl)cyclopentanone, 2.0 g of benzoin, 500.0 g of TiOz, and 20.0 g of accelerator A.
The extrudate i~ ground by known standard procedures to a particle size of ca. 40 um and sprayed with an electrostatic gun on to an aluminium sheet. Stowing for 30 minutes at 200°C gives a varnish film having the following properties:
2 0 film thickness (ym) - 61 Erichsen deep drawing test according to DIN 53 156 (mm) = 9.3 *) impact resistance (cm~kg) = 80 gloss (~ 60°) (%) - 0 yellowness index according to DIN 6167 - 2.8 flow at 200°C~) - good/very good.
) A force of known weight is dropped from a specific height on to the back of the coated aluminium sheet. The value obtained, height (cm) x weight (kg), indicates the greatest impact at which the film 3 0 still remains intact.
***Trade-mark ) Test method in which the flow of the coating is determined visually as moderate, good or very good.
Example 2: A powder coating composition is prepared by mixing the following components in exactly the same manner as in Example 1:
762.5 g of the bisphenol A diglydidyl ether according to Example 1, 5.0 g of Acrylron~ MFP, 153.5 g of Crylcoat~ 314, 79.0 g of 2,2,5,5-tetra(B-carboxyethyl)cyclopentanone, 2.0 g of benzoin, 500.0 g of Ti02, and 20.0 g of curing accelerator A.
After stowing for 30 minutes at 200°C, the film has the following properties:
film thickness (um) - 54 Erichsen deep drawing test (mm) - 8.8 impact resistance (cm~kg) = 80 gloss ( ~( 60° ) (%) _ 4 yellowness index (DIN 6167) - 3.1 flow at 250°C = very good.
Example 3: A powder coating composition is prepared by mixing the following components in exactly the same manner as in Example 1:
931.0 g of the bisphenol A diglycidyl ether according to Example l, 5.0 g of Acrylron~ MFP, 30.1 g of 2,2,5,5-tetra(B-carboxyethyl)cyclopentanone, 37.7 g of tolyl biguanide, 2.0 g of benzoin, and 500.0 g of TiOz.
After stowing for 30 minutes at 200°C, the varnish film has the following properties:
film thickness (um) - 56 Erichsen deep drawing test (mm) - 9.5 impact resistance (cm~kg) = 160 gloss (~( 60°) (%) - 4 yellowness index (DIN 6167) - 3.5 flow at 200°C - good/moderate.
Example 4: A powder coating composition is prepared by mixing the following components in exactly the same manner as in Example 1:
876.0 g of the bisphenol A diglycidyl ether according to Example 1, 5.0 g of Acrylron~ MFP, 92.0 g of carboxyl-terminated polyacetal I, 32.0 g of tolyl biguanide, 2.0 g of benzoin, and 500.0 g of TiOz.
After stowing for 30 minutes at 200°C, the film has the following properties:
film thickness (um) - 66 Erichsen deep drawing test (mm) - 10 impact resistance (cm~kg) = 40 gloss (~ 60°) (%) - 15 yellowness index (DIN 6167) - 6.7 flow at 200°C - very good.
Example 5: A powder coating composition is prepared by mixing the following components in exactly the same manner as in Example 1:
730.0 g of the bisphenol A diglycidyl ether according to Example 1, 5.0 g of Acrylron~ MFP, 27.0 g of tolyl biguanide, 23.0 g of 2,2,4,4-tetra(B-carboxylethyl)pentan-3-one, 2.0 g of benzoin, and 390.0 g of TiOZ.
After stowing for 30 minutes at 200°C, the film has the following properties:
film thickness (um) - 54 Erichsen deep drawing test (mm) - 9.3 impact resistance (cm~kg) = 160 gloss (~( 60°) (~) - 28 yellowness index (DIN 6167) - 4~2 flow at 200°C - good/moderate.
Claims (10)
1. A powder coating composition comprising (a) an epoxy resin, (b) at least one polycarboxylic acid of formula I or II
wherein R1, R2, R3 and R4 are each independently of one another a hydrogen atom, C1-C4alkyl or the radical -CH2-CH2-COOH, R5 and R6 are each independently of the other a hydrogen atom, C1-C4alkyl, the radical -CH2-CH2-COOH or, when taken together, are an unsubstituted or alkyl-substituted methylene or polymethylene group, each of 1 to 7 carbon atoms, with the proviso that at least two of the substituents R1 to R6 are the radical -CH2-CH2-COOH, the substituents R are each independently of one another a hydrogen atom or the radical -15a- the ratio of the carboxyl groups present in the
wherein R1, R2, R3 and R4 are each independently of one another a hydrogen atom, C1-C4alkyl or the radical -CH2-CH2-COOH, R5 and R6 are each independently of the other a hydrogen atom, C1-C4alkyl, the radical -CH2-CH2-COOH or, when taken together, are an unsubstituted or alkyl-substituted methylene or polymethylene group, each of 1 to 7 carbon atoms, with the proviso that at least two of the substituents R1 to R6 are the radical -CH2-CH2-COOH, the substituents R are each independently of one another a hydrogen atom or the radical -15a- the ratio of the carboxyl groups present in the
2-carboxycyclohexanecarbonyl radical to the RO groups being 0.5 to 1.0, m is an integer from 2 to 5, n is an integer from 0 to 10, and X is a direct bond or an aliphatic or cycloaliphatic radical, and (c) a carboxyl-terminated saturated polyester, tolyl biguanide or dicyandiamide.
2. A powder coating composition according to claim 1, wherein the epoxy resin (a) contains on average more than one epoxy group in the molecule.
2. A powder coating composition according to claim 1, wherein the epoxy resin (a) contains on average more than one epoxy group in the molecule.
3. A powder coating composition according to claim 1, which contains a polycarboxylic acid of formula I, wherein R1 to R4 are the carboxyethyl radical and R5 and R6, when taken together, are an unsubstituted or an alkyl-substituted polymethylene group of 2 to 7 carbon atoms.
4. A powder coating composition according to claim 1, which contains a polycarboxylic acid of formula II, wherein X is a direct bond or an aliphatic or cycloaliphatic radical, each containing up to 20 carbon atoms, m is 2 or 3, and n is 0 or a value from 0.1 to 3.
5. A powder coating composition according to claim 1, which contains a polycarboxylic acid of formula II which has a softening temperature in the range from 60 to 180°C.
6. A powder coating composition according to claim 1, wherein the carboxyl-terminated saturated polyester (c) contains on average more than two carboxyl groups per molecule, has an acid number of 15 to 100, and has an average molecular weight in the range from 500 to 10 000.
7. A powder coating composition according to claim 1, wherein the carboxyl-terminated saturated polyester (c) has a glass transition temperature in the range from 40 to 80°C.
8. A powder coating composition according to claim 1, which additionally contains an accelerator.
9. A powder coating composition according to claim 1, which additionally contains a deaerating agent, a levelling agent and/or a pigment.
10. A polycarboxylic acid of formula II
wherein the substituents R are each independently of one another a hydrogen atom or the radical the ratio of the carboxyl groups present in the 2-carboxycyclohexanecarbonyl radical to the RO groups being 0.5 to 1.0, m is an integer from 2 to 5, n is an integer from 0 to 10, and X is a direct bond or an aliphatic or a cycloaliphatic radical.
wherein the substituents R are each independently of one another a hydrogen atom or the radical the ratio of the carboxyl groups present in the 2-carboxycyclohexanecarbonyl radical to the RO groups being 0.5 to 1.0, m is an integer from 2 to 5, n is an integer from 0 to 10, and X is a direct bond or an aliphatic or a cycloaliphatic radical.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH399388 | 1988-10-26 | ||
| CH3993/88-2 | 1988-10-26 |
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| Publication Number | Publication Date |
|---|---|
| CA2001300A1 CA2001300A1 (en) | 1990-04-26 |
| CA2001300C true CA2001300C (en) | 2001-02-06 |
Family
ID=4267811
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2001300 Expired - Fee Related CA2001300C (en) | 1988-10-26 | 1989-10-24 | Powder coating compositions for matt coatings |
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| Country | Link |
|---|---|
| EP (1) | EP0366608B1 (en) |
| JP (1) | JP2847305B2 (en) |
| BR (1) | BR8905436A (en) |
| CA (1) | CA2001300C (en) |
| DE (1) | DE58906442D1 (en) |
| ES (1) | ES2060812T3 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111372967A (en) * | 2017-10-24 | 2020-07-03 | Sika技术股份公司 | Heat-curable epoxy resin composition having high storage stability |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8927375D0 (en) * | 1989-12-04 | 1990-01-31 | Swan Thomas & Co Ltd | Powder coatings |
| EP0506617B1 (en) * | 1991-03-27 | 1996-08-21 | Ciba-Geigy Ag | Curing agent for powder coatings based on polyesters |
| DE4430399C1 (en) | 1994-08-26 | 1996-02-22 | Inventa Ag | Epoxy-free, thermosetting coating system |
| DE4430400A1 (en) * | 1994-08-26 | 1996-02-29 | Inventa Ag | Thermosetting coating system made of several binder resins |
| US6310139B1 (en) | 1999-08-31 | 2001-10-30 | Reichhold, Inc. | Burnish resistant powder coating compositions |
| JP4798422B2 (en) * | 2005-03-01 | 2011-10-19 | Ｄｉｃ株式会社 | Resin composition for powder coating |
| US8476376B2 (en) | 2010-03-11 | 2013-07-02 | Evonik Degussa Gmbh | Heat-curing powder-lacquer compositions yielding a matte surface after curing of the coating, as well as a simple method for production of same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3275599A (en) * | 1961-06-28 | 1966-09-27 | American Cyanamid Co | Resinous composition and process for preparing the same |
| GB1033697A (en) * | 1964-05-27 | 1966-06-22 | Ici Ltd | Curing process for epoxy resins |
-
1989
- 1989-10-17 DE DE89810786T patent/DE58906442D1/en not_active Expired - Fee Related
- 1989-10-17 EP EP19890810786 patent/EP0366608B1/en not_active Expired - Lifetime
- 1989-10-17 ES ES89810786T patent/ES2060812T3/en not_active Expired - Lifetime
- 1989-10-24 CA CA 2001300 patent/CA2001300C/en not_active Expired - Fee Related
- 1989-10-25 BR BR8905436A patent/BR8905436A/en not_active IP Right Cessation
- 1989-10-26 JP JP1279589A patent/JP2847305B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111372967A (en) * | 2017-10-24 | 2020-07-03 | Sika技术股份公司 | Heat-curable epoxy resin composition having high storage stability |
| CN111372967B (en) * | 2017-10-24 | 2023-11-07 | Sika技术股份公司 | Heat-curable epoxy resin composition having high storage stability |
| US11866544B2 (en) | 2017-10-24 | 2024-01-09 | Sika Technology Ag | Heat-curing epoxy resin composition having high storage stability |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2847305B2 (en) | 1999-01-20 |
| ES2060812T3 (en) | 1994-12-01 |
| EP0366608A2 (en) | 1990-05-02 |
| EP0366608A3 (en) | 1990-12-05 |
| EP0366608B1 (en) | 1993-12-15 |
| JPH02170871A (en) | 1990-07-02 |
| DE58906442D1 (en) | 1994-01-27 |
| CA2001300A1 (en) | 1990-04-26 |
| BR8905436A (en) | 1991-04-30 |
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| EEER | Examination request | ||
| MKLA | Lapsed |