JPH0978005A - Thermosetting powder coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in blocking resistance of a coating material and performances such as acid resistance, weather resistance, etc., of a coating film. SOLUTION: This thermosetting powder coating composition comprises (A) a copolymer prepared by radical mechanism composed of the following radical- copolymerizable unsaturated monomer components [(a) 36-50wt.% of an epoxy group-containing unsaturated monomer, (b) 5-45wt.% of a styrene-based monomer, (c) 10-50wt.% of tricyclodecanyl (meth)acrylate monomer and (d) 0-49wt.% of another radical-polymerizable unsaturated monomer except the monomers] and having 40-100 deg.C glass transition temperature and 1,000-15,000 number-average molecular weight and (B) a cross-linking agent as essential components.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel thermosetting powder coating composition.

[0002]

2. Description of the Related Art Conventionally, since powder coating compositions contain almost no volatile components such as organic solvents, they have attracted attention as coatings excellent in pollution prevention and global environment protection.

In general, articles used outdoors (for example,
Thermosetting powder coatings are applied to automobile outer panels, etc., and the coating film formed from itself is strongly required to have performances such as finished appearance, acid resistance, and weather resistance, as can be considered from its application. It

A method for improving the finished appearance of the powder coating composition can be achieved by lowering the glass transition temperature of the powder coating resin or lowering the molecular weight to lower the melt viscosity of the resin. Moreover, the blocking resistance of the powder coating was poor, and it was difficult to satisfy the performance of both.

As a solution to the above-mentioned problems, a resin prepared by copolymerizing a monomer containing a polycyclic aliphatic hydrocarbon group such as tricyclodecanyl (meth) acrylate is used as a resin for thermosetting powder coating. (JP-A No. 7-166103), but it has a drawback that the coating film is inferior in acid resistance.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a specific amount of an epoxy group-containing unsaturated monomer and tricyclodecanyl (meth), respectively. A coating composition using a radical copolymer obtained by combining an acrylate monomer and a styrene monomer as a thermosetting powder coating resin has a blocking resistance, a finished appearance, an acid resistance, a curability and a weather resistance. The inventors have found that they have excellent properties, and have completed the present invention.

That is, the present invention comprises the following components (A) unsaturated monomer component capable of radical polymerization (a) 36 to 50% by weight of an epoxy group-containing unsaturated monomer, and (b) 5 to 45% by weight of a styrene monomer. %, (C) tricyclodecanyl (meth) acrylate monomer 10 to 50% by weight, and (d) other radically polymerizable unsaturated monomer other than those described above 0 to 49% by weight radical copolymer And the copolymer has a glass transition temperature of 40 to 100 ° C. and a number average molecular weight of 1000 to 1
The present invention relates to a thermosetting powder coating composition containing 5000 epoxy group-containing copolymer and (B) a crosslinking agent as essential components.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy group-containing copolymer (A) used in the coating composition of the present invention comprises (a) an epoxy group-containing unsaturated monomer 36 to 50% by weight, and (b) a styrene-based monomer-5. To 45% by weight, (c) tricyclodecanyl (meth) acrylate monomer-10 to 50% by weight, and (d) other radically polymerizable unsaturated monomer other than the above-mentioned radicals of 0 to 49% by weight. Is a copolymer,
The copolymer has a glass transition temperature of 40 to 100 ° C. and a number average molecular weight of 1,000 to 15,000.

Examples of the epoxy group-containing unsaturated monomer (a) include, for example, glycidyl (meth) acrylate, glycidyl allyl ether, 3,4-epoxycyclohexylmethyl (meth) acrylate, and β-methylglycidyl. (Meth) acrylate, allyl glycidyl ether and the like can be mentioned. These monomers can be used alone or in combination of two or more. Among these, glycidyl (meth) acrylate and β-methylglycidyl methacrylate are particularly preferable. The β-methylglycidyl methacrylate is excellent in blocking resistance and smoothness. Also,
Both can be used in combination, and the mixing ratio thereof is preferably in the range of about 5 to 100% by weight of β-methylglycidyl methacrylate in terms of the total amount of both.

Examples of the styrene-based monomer (b) include styrene and α-methylstyrene. These monomers can be used alone or in combination of two or more.

Other monomers (d) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, iso. -Butyl (meth) acrylate, tert-butyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate _C1-24 alkyl esters of (meth) acrylic acid such as; alicyclic ring-containing (meth) acrylic acid esters such as cyclohexyl (meth) acrylate and isobornyl acrylate; Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, hydroxybute Chill (meth) acrylate,
(Poly) ethylene glycol mono (meth) acrylate
And hydroxyl group-containing unsaturated monomers such as hydroxyethyl vinyl ether; nitrile compounds such as (meth) acrylonitrile; ethyl vinyl ether, butyl vinyl ether
Vinyl ethers such as ter and cyclohexyl vinyl ether; tetrafluoroethylene, trifluoroethylene, vinylidene difluoride, trifluoromonochloroethylene, fluoroolefins such as vinyl fluoride, and perfluorobutylethyl Perfluoroalkyl (meth) acrylates such as (meth) acrylate, perfluoroisononylethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate
And fluorine-containing unsaturated monomers such as G. These monomers can be used alone or in combination of two or more.

The blending ratios of the above-mentioned monomers (a) to (d) are as follows in terms of the total amount of the monomers.

Monomer (a): 36 to 50% by weight, preferably 36 to 45% by weight, and when less than 36% by weight, acid resistance, weather resistance, abrasion resistance and the like are deteriorated.
If it exceeds 5% by weight, the storage stability of the coating material and the finished appearance (smoothness, yellowing, etc.) of the coating film deteriorate, which is not preferable.

Monomer (b): in the range of 5 to 45% by weight, preferably 10 to 20% by weight, if less than 5% by weight, blocking resistance, acid resistance, curability, etc. deteriorate, while 4
If it exceeds 5% by weight, the finished appearance (smoothness, gloss, etc.) of the coating film, the storage stability of the coating material, etc. are deteriorated, which is not preferable.

Monomer (c): in the range of 10 to 50% by weight, preferably 15 to 45% by weight, if less than 10% by weight, the melt flowability is poor and the coating film has a finished appearance (smoothness etc.) and acid resistance. On the other hand, if it exceeds 50% by weight, weather resistance, scratch resistance and the like are deteriorated, which is not preferable.

Monomer (d): 0 to 49% by weight, preferably 10 to 45% by weight.

The epoxy group-containing copolymer (A) can be produced by radically polymerizing the mixture of the monomers (a) to (d) in an organic solvent in the presence of a polymerization initiator.

As the organic solvent, the above-mentioned monomer (a) is used.
~ (D) can be used without particular limitation as long as it is an inert organic solvent that does not substantially react, specifically, for example, aromatic compounds such as toluene and xylene, amyl acetate, propyl acetate, butyl acetate, acetic acid. Acetate ester system such as methoxybutyl, methyl acetoacetate, ethyl acetoacetate, methyl cellosolve acetate, cellosolve acetate, diethylene glycol monomethyl ether acetate, carbitol acetate, dioxane, ethylene glycol diethyl ether, ethylene glycol dibutyl ether Examples thereof include ethers such as ether and diethylene glycol diethyl ether, and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone. These can be used alone or in combination of two or more. In the organic solvent, it is preferable to use an aromatic system as a main component (50% by weight or more), and to use it in combination with a solvent other than the aromatic solvent, if necessary.

As the polymerization initiator, conventionally known radical polymerization initiators can be used without particular limitation. Specifically, for example, benzoyl, di-tert-butyl hydroper oxide, tert-butyl hydroper oxide, cumylper oxide, cumene hydroper.
Oxide, diisopropylbenzan hydroperoxide, tert-butylperoxybenzoate, laurylperoxide, acetylperoxide, te
rt-butyl-2-ethylhexanoate, tert-
Amylpa-oxy-2-ethylhexanoate, 1,
Peroxides such as 1,3,3-tetramethylbutylperoxy-2-ethylhexanoate; 2 ', 2'-azobisisobutyronitrile, azobisdimethylvaleronitrile, azobiscyclohexanecarbo Examples thereof include azo compounds such as nitrile. These can be used alone or in combination of two or more.

The conditions of the radical polymerization reaction are not particularly limited, but are, for example, about 50 to 200 ° C., preferably about 70 to.
About 150 hours at a temperature range of about 1 to 24 hours, preferably about 5 hours.
A range from 10 to 10 hours is preferred.

The organic solvent solution of the above-mentioned epoxy group-containing copolymer (A) is used as a powder resin containing substantially no organic solvent by removing the solvent from the solution by a method such as decompression. If necessary, a component other than the copolymer (for example, a crosslinking agent (B),
Other compounds) can be mixed.

The epoxy group-containing copolymer (A) is
Glass transition temperature 40 to 100 ° C, preferably 50 to 80
It has a range of ° C and a number average molecular weight of 1,000 to 15,000, preferably 3,000 to 10,000. When the glass transition temperature is lower than 40 ° C, the coating has poor blocking resistance. On the other hand, when the glass transition temperature is higher than 100 ° C, the finished appearance (smoothness and the like) of the coating film is not preferable. When the number average molecular weight is less than 1,000, the blocking resistance of the coating material and the weather resistance of the coating film are poor, while when it exceeds 15,000, the finished appearance of the coating film is poor, which is not preferable.

The above-mentioned glass transition temperature (Tg, ° C) is a value obtained by converting the temperature (° K) calculated by the following Fox equation into (° C).

100 / Tg = W ₁ / Tg ₁ + W ₂ / Tg ₂ +
W ₃ / Tg ₃ + W ₄ / Tg ₄ ... (In the formula, W ₁ , W ₂ , W ₃ and W _{4 respectively} represent the weight% of the monomer used in the copolymer. , Tg ₁ , Tg ₂ , Tg
₃ and Tg ₄ represent the glass transition temperature (° K) of the same polymer. ) The glass transition temperature of the polymer is Polymer H
andbook (Second Edition,
J, Brandrup E, H, Immergut
(Eds.) And the manufacturer's catalog values were used unless otherwise stated in the literature. For example, tricyclodecanyl acrylate is 379 ° K, tricyclodecanyl methacrylate is 448 ° K, methylglycidyl methacrylate is 332 ° K, and isobornyl acrylate is 367 ° K.
It is.

Crosslinking agent (B) used in the coating composition of the present invention
Any known cross-linking agent can be used without particular limitation as long as it is a cross-linking agent that reacts and cures with the epoxy group of the epoxy group-containing copolymer (A). Specifically, for example, adipic acid, sebacic acid, suberic acid, succinic acid, glutaric acid,
Maleic acid, fumaric acid, dodecanedioic acid, pimelic acid, azelaic acid, itaconic acid, citraconic acid and other aliphatic polycarboxylic acids and their (poly) anhydrides; terephthalic acid,
Aromatic polycarboxylic acids such as isophthalic acid, phthalic acid, trimellitic acid and pyromellitic acid and their anhydrides; alicyclic polycarboxylic acids such as hexahydrophthalic acid, hexahydroisophthalic acid and methylhexahydrophthalic acid and their (Anhydrous) polycarboxylic acid compounds such as anhydrides, and, for example, benzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, triphenylsulfonium boron tetrafluoride, triphenylsulfonium antimony hexafluoride, p- Sulfonium salts such as tert-butylbenzyl tetrahydrothiophenium antimony hexafluoride; N, N-dimethyl-N-benzylanilinium antimony hexafluoride, N, N-dimethyl-N-benzylanilinium boron tetrafluoride, N , N-
Dimethyl-N- (4-chlorobenzyl) anilinium antimony hexafluoride, N, N-dimethyl-N- (tert
-Phenylethyl) anilinium antimony hexafluoride and other anilinium salts; N-benzyl-4-dimethylaminopyridinium antimony hexafluoride, N-benzyl-4
-Diethylaminopyridinium trifluoromethanesulfonic acid, N, N-dimethyl-N- (4-methoxybenzyl) toluidinium antimony hexafluoride, N, N-diethyl-N- (4-methoxybenzyl) toluidinium Toluidinium such as antimony hexafluoride Salts: Potential cationic polymerization catalysts such as phosphonium salts such as ethyltriphenylphosphonium antimony hexafluoride and tetrabutylphosphonium antimony hexafluoride, and the like. These can be used alone or in combination of two or more.
Further, among the above, dodecanedioic acid has good performances such as blocking resistance of coating material, finished appearance of coating film, and acid resistance.

When the (anhydrous) polycarboxylic acid compound is used with respect to 100 parts by weight of the epoxy group-containing copolymer (B), the mixing ratio of the crosslinking agent (B) is preferably about 10 to 50 parts by weight, preferably A range of about 15-40 parts by weight is preferred. Further, when a latent cationic polymerization catalyst is used, the range of about 0.05 to 5 parts by weight, preferably about 0.2 to 2 parts by weight is suitable. Further, when used in combination, about 10 to 50 parts by weight of (anhydrous) polycarboxylic acid compound, relative to 100 parts by weight of the epoxy group-containing copolymer (B),
A range of about 15 to 40 parts by weight and a latent cationic polymerization catalyst of about 0.05 to 5 parts by weight, preferably about 0.2 to 2 parts by weight is suitable. If the blending amount is less than the above range, the acid resistance, processability, weather resistance and the like are inferior, while if it exceeds the above range, the finished appearance is inferior, which is not preferable.

In the coating composition of the present invention, in addition to the above-mentioned components, for example, color pigments, fillers, fluidity regulators, antiblocking agents, ultraviolet absorbers, ultraviolet stabilizers, surface regulators, anti-armpits agents, and oxidation agents. Other compounds such as an inhibitor, a charge control agent, a curing accelerator, and other resins can be compounded as necessary.

The coating composition of the present invention can be produced, for example, by adding a mixture of the crosslinking agent (B) and, if necessary, other additives to the organic solvent solution of the epoxy group-containing copolymer (A). After removing the solvent to obtain a solid powder resin composition,
In the case where the powder coating can be produced by finely pulverizing with a pulverizer and the epoxy group-containing copolymer (A) is a single solid powder resin containing no components such as the above-mentioned crosslinking agent (B). Is blended with the copolymer (A), the cross-linking agent (B) and, if necessary, other additives, dry-blended with a mixer, then heat-melt kneaded, cooled and finely pulverized. Can be manufactured. Suitably, the average particle size of the powder coating is in the range of about 1-100 microns, preferably about 5-60 microns.

The coating composition of the present invention is powder-coated on an object to be coated and baked (for example, at a temperature of about 140 to 200 ° C. for about 2 minutes).
The cured coating film can be formed by (0 to 40 minutes). The powder coating can be carried out by a method known per se, for example, electrostatic powder coating (corona charging type, friction charging type, etc.), fluidized coating and the like.

The coating film thickness is not particularly limited, but is generally in the range of about 30 to 100 μm, preferably about 40 to 80 μm.

[0031]

EXAMPLES The present invention will be described in detail below with reference to examples. Unless otherwise specified, "part" and "%" are based on weight.

Production Example of Copolymer (a) A reactor equipped with a thermometer, thermostat, stirrer, reflux condenser and dropping device was charged with 85 parts of toluene and heated to 110 ° C. while blowing nitrogen gas. Heat to styrene 15 parts, tricyclodecanyl acrylate 35
Part, n-butyl methacrylate 12 parts, methyl methacrylate 2 parts, glycidyl methacrylate 26 parts, methyl glycidyl methacrylate 10 parts, 2,2'-azobis (2-methylbutyronitrile) ) 4 parts of the mixture were added dropwise over about 3 hours. After finishing the dropping, leave at 110 ° C for 2 hours,
The reaction was completed. Then, toluene was removed by vacuum distillation, and the mixture was cooled to produce a copolymer (a).

Production Examples of Copolymers (b) to (m) Copolymers (b) to (m) were produced in the same manner as the production of copolymer (a) with the formulations shown in Table 1.

[0034]

[Table 1]

Example 1 100 parts of the copolymer (a) and 26 parts of dodecanedioic acid were dry blended with a Henschel mixer at room temperature, and then melt-kneaded with an extruder. Then, after cooling, it was finely pulverized with a pin desk mill and filtered through 150 mesh to obtain Example 1.
Powder coatings were produced.

Examples 2 to 7 Copolymers (b) to (g) were used to manufacture the same as in Example 1 to obtain powder coating materials of Examples 2 to 7. The types of copolymers used in Examples 2 to 7 were the copolymers shown in Table 2.

Comparative Examples 1 to 6 Copolymers (h) to (m) were used to produce the same as in Example 1 to obtain powder coating materials of Comparative Examples 1 to 6.

The results are shown in Table 2.

[0039]

[Table 2]

In Table 2, the test was conducted as follows.

Blocking resistance of the coating material The powder coating material is placed in a cylindrical container having a bottom area of about 20 cm ² so that the height is 6 cm, and allowed to stand at 30 ° C. for 7 days. Then, the powder coating material was taken out and the state was observed. The evaluation is as follows. ◎ is good without any lumps, ○ is slightly lumps but can be easily loosened with fingers, △ is lumps that cannot be loosened without pressing firmly with fingers, × is lumps that can be loosened even with strong pressing with fingers None , coating film preparation conditions Paint and cured coating film were prepared using powder paint.

Thickness 0.8 mm after zinc phosphate conversion treatment
Epoxy cation electrodeposition paint was applied to the dull steel plate of No. 2 to give a dry coating film thickness of about 20 microns, and an automobile intermediate coat surfacer was dried on the baked electrodeposition coating film to a dry film thickness of about 20 microns. After baking as described above, the resultant was sanded with a # 400 sandpaper, drained and dried. Then, Magicron base coat HM-22 (Kansai Paint Co., Ltd., metallic paint, trade name) was applied so as to have a cured film thickness of about 15 microns, and baked and cured at 140 ° C. for 30 minutes in a dryer for testing. I used it as a material.

Then, powder coating is electrostatically coated on the surface of the material to a film thickness of about 70 μm, and dried by a drier to obtain 160
It was heat-cured at 30 ° C. for 30 minutes. The following test was performed on the obtained coated plate.

Appearance of Coating Film The finish appearance of the coating film was evaluated according to the following criteria from glossiness and smoothness. ⊚ is good, ◯ is slightly inferior in smoothness but good in gloss, Δ is slightly inferior, × is inferior, and the specular reflectance was measured at 60 ° gloss 60 °. It was measured according to JISK-5400.

0.4 cc of acid resistant 40% sulfuric acid water was dropped on the surface of the coating film, heated for 15 minutes on a hot plate heated to 85 ° C., washed with water, and the coating film was observed. evaluated. ⊚ is good with no change, ◯ is very good with a slight step difference at the interface between the drip part and the non-drip part, and Δ is inferior because there is a step difference at the interface between the drip part and the non-drop part No., X indicates that the coating film was whitened, yellow coating was applied to the test coated plate (metallic base coat) prepared under the conditions for forming the coating film, and Magicron clear coat (manufactured by Kansai Paint Co., Ltd., clear -Paint, trade name) was applied using an air spray gun so that the cured film thickness would be about 40 microns, and baked and cured at 140 ° C for 30 minutes in a dryer to obtain a coated plate for comparison test. The test coated plate and the comparative coated plate were visually evaluated for comparative yellowness. The evaluation criteria are as follows. ○: no abnormality, △: slightly yellowish compared to the comparative coated plate, ×: marked yellowish compared to the comparative coated plate, exposed to weather-resistant sunshine weatherometer for 1500 hours After that, the coating film was observed and evaluated according to the following criteria. ○: No abnormality, △: Blurred, small cracks occurred, ×: Significant blur, cracked,

[0046]

INDUSTRIAL APPLICABILITY The coating composition of the present invention is used in the epoxy copolymer used in the coating composition. Particularly, by using 36 to 50% by weight of the epoxy group-containing unsaturated monomer, the smoothness is not lowered and the acid resistance is improved. Improves scratch resistance, and also
By using 5 to 45% by weight of styrene monomer, acid resistance and scratch resistance are improved without lowering weather resistance.
Further, by using 10 to 50% by weight of tricyclodecanyl (meth) acrylate monomer, the finish of the coating film is improved without lowering the blocking resistance of the coating material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobushige Numa 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Kansai Paint Co., Ltd. (72) Naoto Adachi 4--17-1, Higashi-Hachiman, Hiratsuka, Kanagawa Kansai Paint Co., Ltd.

Claims (1)

[Claims] 1. The following component (A) unsaturated radical-polymerizable unsaturated monomer component (a) 36 to 50 wt% of an epoxy group-containing unsaturated monomer, (b) 5 to 45 wt% of a styrene monomer, a radical copolymer of c) tricyclodecanyl (meth) acrylate monomer 10 to 50% by weight, and (d) another radically polymerizable unsaturated monomer other than the above, 0 to 49% by weight, Further, the copolymer has a glass transition temperature of 40 to 100 ° C. and a number average molecular weight of 1,000 to 1
A thermosetting powder coating composition comprising 5000 epoxy group-containing copolymer and (B) a crosslinking agent as essential components.