JPH11246794A - Resin composition for powder coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition being of a type of novel crosslinking system and giving a coating film excellent in weather resistance, acid resistance, appearance, and adhesion by using a vinyl copolymer containing silyl groups as the principal crosslinking groups and a carboxyl-containing organic compound as the essential components. SOLUTION: This composition essentially consists of 100 pts.wt. vinyl copolymer comprising 1-30 pts.wt. vinyl monomer having a silyl group represented by the formula (wherein R<1> is a 1-10C alkyl, a 6-10C aryl, or a 7-10C aralkyl; X is H, a halogen, hydroxyl, an alkoxyl, phenoxy, a thioalkoxyl, an acyloxy, amino, or the like; and a is 0-2) as the principal crosslinking group, 1-30 pts.wt. glycidyl-containing vinyl monomer, and 98-40 pts.wt. other copolymerizable vinyl monomers and having a glass transition temperature of 40-100 deg.C and a number-average molecular weight of 2,000-20,000 and 1-30 pts.wt. organic compound having three or more carboxyl groups in the molecule and having a molecular weight of 200-2,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a resin composition for powder coatings. More specifically, for example, relates to a resin composition for powder coatings suitably used for automotive parts, industrial machinery, steel furniture, building interior and exterior, home appliances and the like, and more specifically, excellent water resistance, appearance, heat The present invention relates to a resin composition for powder coatings which exhibits curability, impact resistance, and the like, and exhibits extremely excellent weather resistance.

[0002]

2. Description of the Related Art Conventionally, for painting automotive parts, industrial machines, steel furniture, interior and exterior of buildings, home electric appliances, etc., acid-
A paint mainly containing an ester resin or an epoxy resin by epoxy crosslinking is used. However, although the paint is relatively inexpensive, there is a problem that the weather resistance is extremely reduced when used outdoors.

As a paint having excellent weather resistance outdoors, there is a paint using a fluorine resin. However, in this case, the cost jumps greatly and is not practical. In addition, since the influence on the global environment is regarded as important, solvent-based paints are being shunned by the generation of a large amount of volatile components, and it is necessary to replace solvent-based paints with powder paints.

Polyester resins, which are often used in powder coatings, have a good balance of coating film properties, but do not have sufficient weather resistance. On the other hand, an acrylic resin is used to improve weather resistance, but a physical property balance as high as that of a polyester resin cannot be obtained. Acrylic resins tend to be harder and more brittle than polyester resins, and their mechanical properties and the like are inferior to polyester resins.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an ester resin or an epoxy resin by the above-mentioned acid-epoxy crosslinking which has been frequently used. Overcoming the drawbacks of resin, it not only has excellent weather resistance, but also can provide a coating film with mechanical properties that could not be achieved with conventional acrylic resins, clears environmental problems, and lowers costs To provide a powder coating material having a new cross-linking form, which can be manufactured by the above method.

[0006]

SUMMARY OF THE INVENTION The present invention provides a novel resin composition having the following constitution, thereby achieving the above object. 1) Component (A): 100 parts by weight of a vinyl copolymer comprising the following components (a), (b) and (c): Component (a): a silyl group represented by the following general formula (1): 1 to 30 parts by weight of vinyl monomer contained (b) Component: vinyl monomer containing glycidyl group 1
Component (c): 98 to 40 parts by weight of a copolymerizable vinyl monomer other than component (a) and component (b) Component (B): 3 or more components per molecule 1 to 30 parts by weight of an organic compound containing a carboxyl group The above component (A) and the component (B) are essential components, and the component (A) is mainly a crosslinkable silyl group represented by the following general formula (1). And a glass transition temperature of 40 to 10
A resin composition for powder coatings having a number average molecular weight of 2000 to 20,000 at 0 ° C.

[0007]

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(Wherein R ¹ is an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and 7 to 10 carbon atoms)
And at least one group selected from the group consisting of aralkyl groups. In the case of a plurality of groups, they may be the same or different. X is at least one member selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, a phenoxy group, a thioalkoxy group, an acyloxy group, an aminoxy group, a ketoximate group, an amino group, an amide group, and an alkenyloxy group. Group, and when there are a plurality of groups, they may be the same or different. a is an integer of 0 to 2. 2) A crosslinkable and curable polymer other than the component (A) is included, and the component (A) is at least 20% by weight and less than 100% by weight of the total of the component (A) and the polymer. The resin composition for powder coating according to the above 1).

3) The resin composition for a powder coating according to the above 1) or 2), wherein X in the general formula (1) is an alkoxy group. 4) The component (a) comprises 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane and 3- (meth) The resin composition for a powder coating according to any one of 1) to 3), wherein the resin composition is at least one selected from the group consisting of acryloxypropylmethyldiethoxysilane.

5) The component (b) is at least one selected from the group consisting of glycidyl (meth) acrylate, 2-methylglycidyl (meth) acrylate and allyl glycidyl ether. The resin composition for a powder coating material according to any one of 4). 6) The resin composition for a powder coating according to any one of 1) to 5) above, wherein the molecular weight of the component (B) is from 200 to 2,000.

The component (A) has a composition represented by the general formula (1).
Component (a), which is a vinyl monomer containing a ril group,
Component (b) which is a vinyl monomer containing a ricidyl group
And copolymers other than those (a) and (b)
Copolymerizing component (c), a possible vinyl monomer
Manufactured by The component (a) has the general formula (1)
There is no particular limitation as long as it has a silyl group represented by
If CH_Two= CHSi (OCH_Three)_Three, CH_Two= CHSi
(CH_Three) (OCH_Three)_Two, CH_Two= C (CH_Three) Si (O
CH_Three)_Three, CH_Two= C (CH_Three) Si (CH_Three) (OC
H_Three)_Two, CH_Two= CHSi (OC_TwoH_Five)_Three, CH_Two= CH
Si (OC_ThreeH₇)_Three, CH_Two= CHSi (OC_FourH₉)_Three,
CH_Two= CHSi (OC₆H₁₃)_Three, CH_Two= CHSi (O
C₈H₁₇)_Three, CH_Two= CHSi (OC_TenH_{twenty one})_Three, CH_Two
= CHSi (OC₁₂H_{twenty five})_Three, CH_Two= CHCOO (CH
_Two)_ThreeSi (OCH_Three)_Three, CH_Two= CHCOO (CH_Two)_Three
Si (CH_Three) (OCH_Three)_Two, CH_Two= C (CH_Three) CO
O (CH_Two)_ThreeSi (OCH_Three)_Three, CH_Two= C (CH_Three) C
OO (CH_Two)_ThreeSi (CH_Three) (OCH_Three)_Two, CH_Two= C
HCOO (CH_Two)_ThreeSi (OC_TwoH_Five)_Three, CH_Two= CHC
OO (CH_Two)_ThreeSi (CH_Three) (OC_TwoH_Five)_Two, CH_Two=
C (CH_Three) COO (CH_Two)_ThreeSi (OC_TwoH_Five)_Three, CH
_Two= C (CH_Three) COO (CH_Two)_ThreeSi (CH_Three) (OC_Two
H_Five)_Two, CH_Two= CHCOO (CH_Two)_ThreeSi (OCH_TwoC
H_TwoOCH_Three)_Three, CH_Two= CHCOO (CH_Two)_ThreeSi (C
H_Three) (OCH_TwoCH_TwoOCH_Three)_Two, CH_Two= C (CH_Three)
COO (CH_Two)_ThreeSi (OCH_TwoCH_TwoOCH_Three)_Three, CH
_Two= C (CH_Three) COO (CH_Two)_ThreeSi (CH_Three) (OC
H_TwoCH_TwoOCH_Three)_Two, CH_Two= C (CH_Three) COO (CH
_Two)_TwoO (CH_Two)_ThreeSi (OCH_Three)_Three, CH_Two= C (C
H_Three) COO (CH_Two)_TwoO (CH_Two)_ThreeSi (CH_Three) (O
CH_Three)_Two, CH_Two= C (CH_Three) COO (CH_Two)₁₁Si
(OCH_Three)_Three, CH_Two= C (CH_Three) COO (CH_Two)₁₁
Si (CH_Three) (OCH_Three)_Two, CH_Two= CHCH_TwoOCO
(Ort-C₆H_Four) COO (CH_Two)_ThreeSi (OCH_Three)_Three
(Ort-C₆H_FourRepresents an orthophenylene group), C
H_Two= CHCH_TwoOCO (ort-C₆H_Four) COO (CH
_Two)_ThreeSi (CH_Three) (OCH_Three)_Two, CH_Two= CH (C
H_Two)_FourSi (OCH_Three)_Three, CH_Two= CH (CH _Two)₈Si
(OCH_Three)_Three, CH_Two= CHO (CH_Two)_ThreeSi (OC
H_Three)_Three, CH_Two= CHCH_TwoO (CH_Two)_ThreeSi (OC
H_Three)_Three, CH_Two= CHCH_TwoOCO (CH_Two)_TenSi (O
CH_Three)_Three, CH_Two= CH (para-C₆H_Four) Si (O
CH_Three)_Three, CH_Two= CH (para-C₆H_Four) Si (C
H_Three) (OCH_Three)_Two(Para-C₆H_FourThe parafeni
Len group), CH_Two= C (CH_Three) (Para-C₆
H_Four) Si (OCH_Three)_Three, CH_Two= C (CH_Three) (Par
a-C₆H_Four) Si (CH_Three) (OCH_Three) _TwoArco such as
Xysilyl group-containing monomer; CH_Two= CHCOO (CH_Two)
_ThreeSi (CH_Three) Cl_Two, CH_Two= CHCOO (CH_Two)_ThreeS
iCl_Three, CH_Two= C (CH_Three) COO (CH_Two)_ThreeSi
(CH_Three)_TwoCl, CH_Two= C (CH_Three) COO (CH_Two)_Three
Si (CH_Three) Cl_Two, CH_Two= C (CH_Three) COO (CH
_Two)_ThreeSiCl_ThreeA halosilyl group-containing monomer such as CH;_Two=
C (CH_Three) COO (CH_Two)_ThreeSi (OH)_Three, CH_Two=
C (CH_Three) COO (CH_Two)_ThreeSi (CH_Three) (OH)_Two
Such as silanol group-containing monomers; CH_Two= C (CH_Three) C
OO (CH_Two)_ThreeSi (OCOCH_Three)_ThreeAcetoxy
Silyl group-containing monomers are exemplified.

Of these, alkoxysilyl group-containing monomers are particularly preferred in view of cost and stability. For example, 3- (meth) acryloxypropyltrimethoxysilane and 3- (meth) acryloxypropyltrimethoxysilane are preferred. At least one selected from the group consisting of ethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, and 3- (meth) acryloxypropylmethyldiethoxysilane, or a mixture of two or more of these. . Here, “(meth) acryloxy” means “methacryloxy or acryloxy”. Note that the term “(meta)” used in the following also means the same notation.

These silyl group-containing vinyl monomers include:
One or two or more of them may be used in combination, and 1 to 3 parts by weight of 100 parts by weight of a vinyl copolymer containing a silyl group-containing vinyl monomer (hereinafter, simply referred to as “vinyl copolymer”).
0 parts by weight are copolymerized. The copolymer is preferably copolymerized in an amount of preferably 2 to 25 parts by weight, more preferably 5 to 23 parts by weight. If the amount of copolymerizing the silyl group-containing vinyl monomer is less than 1 part by weight, the curing properties of the resin composition, the mechanical strength of the coating film, and the durability are inferior. Storage stability decreases.

The vinyl monomer containing a glycidyl group as the component (b) is not particularly limited, and includes, for example, glycidyl (meth) acrylate, 2-methylglycidyl (meth) acrylate, allyl glycidyl ether and the like. At least one selected from the group, or two of these
And the like. One or two or more of these components (b) may be used in combination, and 1 to 3 parts by weight per 100 parts by weight of the component (A) obtained using these monomers.
0 parts by weight are copolymerized. Preferably, it is copolymerized in an amount of 2 to 26 parts by weight, more preferably 5 to 25 parts by weight.
When the amount of the component (b) is less than 1 part by weight, the mechanical properties of the coating film are poor. When the amount exceeds 30 parts by weight, the smoothness is reduced.

The other copolymerizable vinyl monomer of the component (c) is not particularly limited. Examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate,
Vinyl monomers such as butyl (meth) acrylate, isobutyl (meth) acrylate, benzyl (meth) acrylate and cyclohexyl (meth) acrylate; styrene, α-methylstyrene, chlorostyrene, 4-hydroxystyrene, vinyltoluene and the like Aromatic hydrocarbon vinyl monomers; α, β-ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, fumaric acid, and citraconic acid Acids having a polymerizable carbon-carbon double bond such as acids, styrene sulfonic acids and vinyl sulfonic acids; or salts thereof (alkali metal salts, ammonium salts, amine salts, etc.); acid anhydrides such as maleic anhydride Or half esters thereof with a linear or branched alcohol having 1 to 20 carbon atoms (Meth) acrylate having an amino group such as dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate; (meth) acrylamide, α-ethyl (meth) acrylamide, N-butoxymethyl (Meth) acrylamide, N,
N-dimethylacrylamide, N-methylacrylamide, acryloylmorpholine or their hydrochloric acid,
Acetate; vinyl ester and allyl ester compounds such as vinyl acetate, vinyl propionate, and diallyl phthalate;
Nitrile group-containing vinyl monomers such as (meth) acrylonitrile; 2-hydroxyethyl (meth) acrylate;
2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl vinyl ether, N-methylol (meth) acrylamide, hydroxystyrene, 2-hydroxy-3-phenoxypropyl acrylate (manufactured by Toa Gosei Chemical Co., Ltd., trade name: ARONIX M-) 5700),
Hydroxyl-containing vinyl monomers such as hydroxyl-modified vinyl-modified hydroxyalkyl vinyl monomers; hydroxyalkyl esters of α, β-ethylenically unsaturated carboxylic acids such as hydroxyalkyl esters of (meth) acrylic acid; Phosphoric ester group-containing vinyl compounds or vinyl compounds such as (meth) acrylate containing urethane bond or siloxane bond; AS-6, AN-6, AA-6, A
Methacryloyl group-containing macromonomers such as B-6 and AK-5 (all manufactured by Toa Gosei Chemical Co., Ltd.); and others such as vinyl methyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, butadiene, and N-vinylimidazole. And vinyl monomers.

The copolymer of the component (A) has a silyl group represented by the general formula (1) as a crosslinkable group. The silyl group is a main crosslinkable group having a function of crosslinking between molecules, and the component (A) may further have a glycidyl group of the component (b) as a crosslinkable group. And other crosslinkable groups.
The number of the silyl groups among all the crosslinkable groups present in the component (A) is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more. It is preferable that at least one, more preferably 2 to 10 silyl groups are present in one molecule of the component (A). It is preferable that at least one glycidyl group is present in one molecule of the component (A), more preferably 2 to 10 glycidyl groups.

As the method for producing the component (A), known polymerization methods such as bulk polymerization, suspension polymerization, and solution polymerization can be used. Particularly, from the viewpoint of ease of synthesis, peroxides, azo compounds, and the like can be used. Solution polymerization using a radical initiator is preferred. Polymerization solvents used in the solution polymerization include hydrocarbons (toluene, xylene, n-hexane, cyclohexane, etc.), acetates (ethyl acetate, butyl acetate, etc.), alcohols (methanol, ethanol, isopropanol, n-butanol). Non-reactive solvents such as ethers (ethyl cellosolve, butyl cellosolve, cellosolve acetate, etc.), ketones (methyl ethyl ketone, ethyl acetoacetate, acetylacetone, diacetone alcohol, methyl isobutyl ketone, acetone, etc.) There is no.

The initiator used for the solution polymerization is not particularly limited, but may be an organic peroxide such as benzoyl peroxide or tert-butyl peroxide, or 2,2 '.
-Azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile),
Radical initiators such as azo compounds such as 2,2′-azobis (2-cyclopropylpropionitrile) and 2,2′-azobis (2-methylbutyronitrile) are exemplified.

In the above solution polymerization, if necessary, n
-Dodecyl mercaptan, t-dodecyl mercaptan,
n-octyl mercaptan, n-octadecyl mercaptan, 3-mercaptopropyltrimethoxysilane, 3
- mercaptopropyl triethoxysilane, 3-mercaptopropyl methyldiethoxysilane Mexico silane, 3-mercaptopropyl methyl diethoxy _{silane, (H 3 CO) 3 Si} -S
_{-S-Si (OCH 3) 3} , (H 3 CO) 3 Si-S 6 -S
The molecular weight can be adjusted using a chain transfer agent such as i (OCH ₃ ) ₃ . In particular, when a chain transfer agent having an alkoxysilyl group in the molecule, for example, 3-mercaptopropyltrimethoxysilane, an alkoxysilyl group can be introduced into the terminal of the silyl group-containing acrylic copolymer.

In the above solution polymerization, a predetermined amount of the above-mentioned monomers, initiator, chain transfer agent and the like are added to a polymerization solvent, polymerization is carried out, and the solvent is removed under reduced pressure. A) The component is obtained. The number average molecular weight of the component (A) is preferably from 2,000 to 20,000, more preferably from 3,000 to 10,000. Molecular weight 20
When it is less than 00, it is difficult for the coating film to exhibit sufficient mechanical properties, and when it exceeds 20,000, there is a problem that the smoothness of the coating film is poor.

Further, the glass transition temperature of the component (A) is as follows:
40 to 100 ° C is preferable, and more preferably 50 to 80 ° C.
° C. When the temperature is lower than 40 ° C., the storage stability of the powder coating material is poor. On the other hand, when the temperature is higher than 100 ° C., the smoothness of the coating film is poor. The component (A) is a crosslinkable and curable copolymer that forms a siloxane bond by the action of moisture. In the present invention, a crosslinkable and curable polymer other than the component (A) (hereinafter also referred to as a polymer (A ′)) can be used together with the component (A). The polymer (A ') includes a homopolymer and a copolymer, and examples thereof include an epoxy resin, a polyester resin, an acrylic resin, and a silicone resin, and one or more of them can be used. The polymer (A ′) can have any crosslinkable group such as an epoxy group and a hydroxyl group as a crosslinkable group in addition to the silyl group represented by the general formula (1).

When the polymer (A ') is used in combination, the component (A) is preferably used in an amount of 20% by weight or more and less than 100% by weight of the total of the component (A) and the polymer (A'), and 30% by weight or more. Is preferably 50% by weight or more, more preferably 80% by weight or more. The organic compound containing three or more carboxyl groups in one molecule, which is the component (B), is not particularly limited as long as it has a molecular weight of 200 to 1,000, and examples thereof include trimethylolpropane and trimethyloloctane. A reaction product of a trialcohol and / or a tetraalcohol such as pentaerythritol with an acid anhydride such as succinic anhydride, maleic anhydride, phthalic anhydride, hexahydrophthalic anhydride, and 4-methylhexahydrophthalic anhydride; Partial reactants are mentioned.

Among these, 1 mol of trimethylolpropane and 3 m of 4-methylhexahydrophthalic anhydride are used in view of the balance of physical properties such as curability and mechanical strength of the coating film.
ol reactant, 1 mol of trimethyloloctane and 4-mol
A reaction product of 3 mol of methylhexahydrophthalic anhydride, a reaction product of 1 mol of pentaerythritol and 4 mol of 4-methylhexahydrophthalic anhydride shown in the following chemical formula 3 are preferable.

[0024]

Embedded image

The component (B) is the same as the component (A) 100
It is used in an amount of 1 to 30 parts by weight, preferably 2 to 20 parts by weight, and more preferably 2 to 10 parts by weight based on parts by weight. The ratio of the number of glycidyl groups in the component (A) to the number of carboxyl groups in the organic compound of the component (B) is preferably 1: 3 to 3: 1, and more preferably 1: 3.
A range of 2-2: 1 is preferred.

In the resin composition for powder coating of the present invention, the carboxyl group in the component (B) can serve as a catalyst for hydrolysis / condensation of the silyl group represented by the general formula (1). Crosslinking of the silyl groups represented by the general formula (1) in the component (A) and crosslinking of the carboxyl group of the component (B) and the glycidyl group of the component (A) occur simultaneously. A curing catalyst can be added for further smooth progress.

As the curing catalyst, any curing catalyst can be used without particular limitation as long as it promotes the hydrolysis reaction of the silyl group represented by the general formula (1) of the component (A) and can promptly cause a condensation reaction. Organic sulfonic acid, a mixture or a reaction product of an organic sulfonic acid and a nitrogen-containing compound, phosphoric acid or a phosphoric acid ester, an organometallic compound, and the like. Specific examples of the curing catalyst include, for example, organic sulfonic acid compounds such as dodecylbenzenesulfonic acid, p-toluenesulfonic acid, 1-naphthalenesulfonic acid, and 2-naphthalenesulfonic acid; the organic sulfonic acid compound and a nitrogen-containing compound ( For example, 1-amino-2-propanol, monoethanolamine, diethanolamine, 2- (methylamino) ethanol, 2-dimethylethanolamine, 2-
Amino-2-methyl-1-propanol, diisopropanolamine, 3-aminopropanol, 2-methylamino-2-methylpropanol, morpholine, oxazolidine, 4,4-dimethyloxazolidine, 3,4,4
Mixtures or reactants with trimethyl oxazolidin; phosphoric acid, monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, monooctyl phosphate, monododecyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, didodecyl phosphate, etc. Phosphoric acid or phosphoric acid ester of propylene oxide, butylene oxide, cyclohexene oxide, glycidyl methacrylate, glycidol, acrylic glycidyl ether, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycid Xypropyl trimethyldimethoxysilane, Yuka Shell Epoxy Co., Ltd. Cardura E, Yuka Shell Epoxy (Ltd.) of Epikote 828,
Addition products of an epoxy compound such as Epicoat 1001 and phosphoric acid and / or monophosphate; hexylamine, di-2-ethylhexylamine, N, N-dimethyldodecylamine, DABCO, DBU, morpholine, diisopropanolamine, etc. Amines; reactants of these amines with acidic phosphoric acid esters; alkaline compounds such as sodium hydroxide and potassium hydroxide; quaternary ammonium salts such as benzyltriethylammonium chloride or bromide, tetrabutylammonium chloride or bromide; Phosphonium salts: divalent tin compounds such as tin octylate, tin stearate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetylacetonate Divalent tin compounds such as dibutyltin compounds such as dibutyltin bistriethoxysilicate, dibutyltin distearate, and dibutyltin maleate; dioctyltin compounds such as dioctyltin diversate, dioctyltin dilaurate, dioctyltin distearate, and dioctyltin maleate Organic titanate compounds such as tetramethoxytitanium and tetrastearyloxytitanium; organic aluminum compounds such as aluminum isopropoxide and aluminum acetylacetonate; and organic zirconium compounds such as zirconia stearate and zirconium tetraacetylacetonate.

Of these, organic titanate compounds and organic zirconium compounds are preferred from the viewpoint of curability during baking. These curing catalysts may be used alone or in combination. The amount of the curing catalyst used is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the component (A). If the amount is more than 10 parts by weight, problems such as lack of storage stability and deterioration of the appearance of the coating film occur.

The resin composition for powder coatings may contain, if necessary, resins such as polyester, epoxy and acrylic, inorganic pigments such as titanium dioxide, carbon black, iron oxide and chromium oxide, and phthalocyanine-based and quinacdrine-based resins. Additives such as organic pigments, coloring aids, spreading agents and defoamers, ultraviolet absorbers, antistatic agents and antiblocking agents can be added. The mixing ratio of these additives can be appropriately selected according to the required characteristics, and they can be used as a mixture.

The production of the powder coating is performed, for example, by using a heating roll,
Using a melt kneader such as a kneader, the resin composition for a powder coating of the present invention containing the above additives as necessary is melted, kneaded, cooled, and then pulverized. Alternatively, a method in which a curing catalyst, a pigment, an additive, and the like are added to and mixed with the solution after polymerization of the component (A) to obtain the resin composition for powder coating of the present invention, and this is spray-dried can also be used.

The powder coating obtained in this manner is applied to a substrate by a known method such as electrostatic coating or fluid immersion coating. The thickness of the coating film can be appropriately selected as needed, and is usually 20 to 200 μm, preferably 40 to 150 μm.
μm is good. When the thickness is less than 20 μm, the coating film tends to be uneven, and when the thickness is more than 200 μm, there is a problem that the coating film tends to have irregularities.

The obtained coated product is usually at 150 to 220 ° C.
By baking at a temperature of about 5 minutes to 1 hour, it can be sufficiently cured, and a cured product (coating film) having excellent physical properties such as weather resistance and acid resistance can be formed. Fifteen
If the temperature is lower than 0 ° C or shorter than 5 minutes, the coating film is not sufficiently cured. If the temperature is higher than 220 ° C or longer than 1 hour, workability deteriorates and costs such as utility costs increase. Problem arises.

The composition of the present invention is used, for example, for building interiors and exteriors such as aluminum siding and fences, road materials such as guardrails, and home appliances such as air conditioners and refrigerators.

[0034]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. In addition, the part shown below shall show a weight part unless there is particular notice. The analysis values, characteristic values, and performance of the coating film in the examples were measured or evaluated by the following methods. Analytical values (1) Number average molecular weight of polymer Measured by gel permeation chromatography (GPC). Using a Waters 600 GPC system, chloroform was used as the mobile phase and the flow rate was 1 m.
L / min. The column temperature was measured at 40 ° C. The number average molecular weight was calculated using polystyrene as a standard sample. (2) Glass transition temperature Differential scanning calorimeter (DSC, Shimadzu Corporation DSC-
50 type) under a nitrogen atmosphere at a heating rate of 5 ° C./mi.
n and determined. Characteristic value and performance of coating film (1) Appearance Appearance and smoothness were visually evaluated. ：: extremely good, ：: good, Δ: gloss, ×: poor (2) Weather resistance The appearance of the coating film after 3000 hours of irradiation with a sunshine weather meter was visually evaluated. ◎: extremely good, ○: slightly glossy, Δ: glossy,
×: cracking and peeling (3) Acid resistance The coating film appearance after immersing the coating film in a 5% aqueous sulfuric acid solution at room temperature for 24 hours was visually evaluated. ◎: extremely good, ○: slightly glossy, Δ: glossy,
×: cracking, peeling (4) Curability 1 g of the baked composition was wrapped in a 200-mesh stainless steel wire gauze, immersed in acetone for 24 hours, and the weight change of the composition was examined. 1
00%. ◎: 90% or more, ：: 90 to 80%, Δ: 80 to 70
%, ×: 70% or less (5) Adhesion The adhesion was evaluated by a grid tape method according to JIS K5400. ◎: No missing portion, ○: Within 5% of missing portion, Δ: 5% of missing portion
１５15%, ×: 15% or more of defective part (6) Storage stability The change in gel fraction before and after storage was examined as a measure of the progress of gelation of powder coatings stored at 40 ° C. for one month. ◎: no change, ：: change in gel fraction within 5%, Δ: 5%
Gel fraction change of １５15%, ×: Gel fraction change of 15% or more Resin Production Examples 1-4 50 parts of toluene was placed in a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen gas inlet tube and a dropping funnel. After charging and raising the temperature to 110 ° C. while introducing nitrogen gas, a monomer mixture containing a copolymer component shown in Table 1 was added dropwise to the mixture by a dropping funnel.
The solution was dropped at a constant speed over time. After the mixture is dropped, 2,2'-
A mixture of 0.5 parts of azobisisobutyronitrile and 10 parts of toluene was dropped at a constant speed over 1 hour. After the completion of dropping, 110
After heating at ℃ for 1 hour, it was cooled. By distilling off the solvent from the resin solution under reduced pressure, the solid-state resins (a-1) to (a)
-4) was obtained.

[0035]

[Table 1]

Comparative Resin Production Examples 1 to 3 Using monomer mixtures containing the copolymer components shown in Table 2,
In the same manner as in the resin production example, the solid-state resin (c-
1) to (c-3) were obtained.

[0037]

[Table 2]

Examples 1-4 Using Resins (a-1) to (a-4), all components were dry-blended (manufactured by Mitsui Chemicals, Ltd.) according to the formulation (shown in parts) in Table 3. , Trade name Henschel mixer)
After mixing uniformly for 1 minute, the mixture is melt-kneaded using an extrusion kneader (manufactured by BUSS, trade name: BUSS Kneader PR-46) at a temperature of 100 to 110 ° C., cooled, and then jet-milled (Seishin Enterprise) Finely pulverized using a single track jet mill STJ200 (trade name, manufactured by Co., Ltd.) to obtain a powder coating (A-1) having an average particle size of 30 μm.
(A-4) was produced. The obtained powder coating is applied to a thickness of 0.8
Electrostatic spraying machine (trade name Airmatic Spray Gun PEM, manufactured by Wagner Spray Tech Co., Ltd.) so that the film thickness becomes 50 to 60 μm on a zinc phosphate-treated steel sheet having a thickness of 50 mm.
-C1) and baked at 180 ° C. for 20 minutes to form a coating film. The results of evaluating the performance of the obtained coating film are shown in Table 3.

[0039]

[Table 3]

Comparative Examples 1 to 3 According to Table 4, the same procedures as in the examples were carried out to produce powder coatings (C-1) to (C-3). Further, coating was performed in the same manner as in the Production Example, and the results of evaluating the performance of the obtained coating film are shown in Table 4.

[0041]

[Table 4]

[0042]

According to the present invention, excellent weather resistance, acid resistance,
It is possible to provide a powder coating having a new cross-linking form, which has appearance and adhesion, clears environmental problems, and can be manufactured at low cost.

Claims (6)

[Claims] 1. Component (A): 100 parts by weight of a vinyl copolymer comprising the following components (a), (b) and (c): Component (a): represented by the following general formula (1) 1 to 30 parts by weight of a vinyl monomer containing a silyl group (b) Component: vinyl monomer 1 containing a glycidyl group
Component (c): 98 to 40 parts by weight of a copolymerizable vinyl monomer other than component (a) and component (b) Component (B): 3 or more components per molecule 1 to 30 parts by weight of an organic compound containing a carboxyl group The above component (A) and the component (B) are essential components, and the component (A) is mainly a crosslinkable silyl group represented by the following general formula (1). And a glass transition temperature of 40 to 10
A resin composition for powder coatings having a number average molecular weight of 2000 to 20,000 at 0 ° C. Embedded image (Wherein R ¹ is an alkyl group having 1 to 10 carbon atoms, 6 carbon atoms)
At least one group selected from the group consisting of an aryl group having 10 to 10 and an aralkyl group having 7 to 10 carbon atoms,
In the case of a plurality, they may be the same or different. X is a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, a phenoxy group, a thioalkoxy group, an acyloxy group, an aminoxy group, a ketoximate group, an amino group,
It is at least one group selected from the group consisting of an amide group and an alkenyloxy group, and when there are a plurality of groups, they may be the same or different. a is an integer of 0 to 2. ) 2. It contains a crosslinkable and curable polymer other than the component (A), and the component (A) accounts for 20% by weight or more and less than 100% by weight of the total of the component (A) and the polymer. The resin composition for a powder coating according to claim 1, wherein: 3. The resin composition for a powder coating according to claim 1, wherein X in the general formula (1) is an alkoxy group. 4. The component (a) comprises 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane and 3- (meth) acryloxypropylmethyldimethoxysilane.
The resin composition for powder coating according to any one of claims 1 to 3, wherein the resin composition is at least one selected from the group consisting of (meth) acryloxypropylmethyldiethoxysilane. 5. The method according to claim 1, wherein the component (b) is glycidyl (meth).
2. The method according to claim 1, wherein the acrylate is at least one selected from the group consisting of acrylate, 2-methylglycidyl (meth) acrylate and allyl glycidyl ether.
5. The resin composition for a powder coating according to any one of items 4 to 4. 6. The molecular weight of the component (B) is from 200 to 2
000.
Item 10. The resin composition for a powder coating according to item 8.