JP2002173637A - Thermosetting powdery paint composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powdery paint excellent in resistance against the contamination of an acrylic paint, mechanical property, adhesivity to overcoat and low-temperature curability, producible at a relatively low cost, and comprising a polyester resin having little environmental load and excellent weatherability. SOLUTION: The thermosetting powdery paint has a functional group such as a carboxyl group, and it is a powdery paint comprising a carboxyl-containing polyester resin, a β-hydroxyalkylamide curing agent and multilayered organic particles. The portion of >=70 mol% of the total acid components in the carboxyl-containing polyester resin is an aromatic polyvalent carboxylic acid, the acid value of the solid of the resin is 10-100, and the softening point of the resin is 80-150 deg.C. The weight average particle size of the multilayered organic fine particles is 0.1-5 μm, at least one layer of the inner layers of the particle is a cross-linked polymer layer having a glass transition temperature (Tg) of <=20 deg.C, and the outermost layer of the particle is a polymer layer having Tg of >=40 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is an acrylic contamination resistance, low-temperature curability, adhesion to a topcoat, excellent water secondary adhesiveness to the substrate, to a polyester resin-based powder coating having good mechanical properties .

[0002]

2. Description of the Related Art In recent years, interest in powder coatings that do not use solvents has been increasing due to environmental concerns, and powder coatings having excellent low-temperature curability have been used for members having a large heat capacity and members that are liable to undergo thermal deterioration. Paints are desired. Above all, an acrylic resin-based powder coating excellent in low-temperature curability, smoothness, corrosion resistance, and weather resistance is used as an undercoat for members such as aluminum wheels for automobiles. However, since the acrylic resin-based powder coating is expensive, there is a case where it is desired to use an inexpensive powder coating even if a part of the performance is deteriorated. On the other hand, polyester resin-based powder coatings are relatively inexpensive, but they are incompatible with acrylic resin-based powder coatings. And greatly reduced appearance, reduced smoothness,
Corrosion resistance may be reduced. Therefore, it has been difficult to use a polyester resin-based powder coating in a common use of a coating line using an acrylic resin-based powder coating or near the coating line. Therefore, there is a demand for a polyester resin-based powder coating material that does not decrease in smoothness even if a small amount of the acrylic resin-based powder coating material is mixed (herein referred to as acrylic mixing resistance). In addition, polyester resin powder coating using a blocked isocyanate-based curing agent,
The dissociation temperature of the blocking agent was high and curing at low temperatures was difficult, and the degree of release of the dissociated blocking agent into the atmosphere and imposing a load on the environment was large. JP-A-2-3458 proposes a powder coating composition using a carboxyl group-containing polyester resin and a β-hydroxyalkylamide curing agent. However, the acrylic mixing resistance and the mechanical properties at the time of low-temperature curing were not satisfactory. JP 2
Japanese Patent Application Laid-Open No. 000-1633 proposes a polyester powder coating composition containing multilayer polymer particles containing a grafting monomer and having improved workability and impact resistance of a coating film. However, triglycidyl isocyanurate or epoxy group-containing resin is used as a curing agent for the polyester resin having a carboxyl group, and there is a problem of health for workers such as rash, and addition of a catalyst etc. to improve low-temperature curability. What was satisfactory was that the storage stability might be reduced due to the solid phase reaction between the carboxyl group and the epoxy group in the paint.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides an excellent resistance to acrylic contamination, mechanical properties, adhesion to an overcoat, and low-temperature curability, relatively low cost, and low environmental impact. An object of the present invention is to provide a powder coating using a good polyester resin.

[0004]

The thermosetting powder coating composition of the present invention contains a carboxyl group-containing polyester resin, a β-hydroxyalkylamide curing agent represented by the following formula, and multilayer organic fine particles. In a powder coating, 70% by mole or more of the total acid component of the carboxyl group-containing polyester resin is an aromatic polycarboxylic acid, the acid value of the resin solid content is 10 to 100, and the softening point of the resin is 80
And a weight average particle diameter of the organic fine particles having a multilayer structure of 0.1 to 5 μm, and at least one of the inner layers is a crosslinked polymer layer having a glass transition temperature (Tg) of 20 ° C. or less. The outermost layer is a polymer layer having a Tg of 40 ° C. or higher, and has at least one functional group of carboxyl group, hydroxyl group and epoxy group;
0.5 parts by weight of the organic fine particles having a multilayer structure
It is a thermosetting powder coating composition characterized by containing about 20 parts by weight.

[0005]

Embedded image (Wherein R ¹ is a hydrogen atom, a methyl group or an ethyl group,
R ² represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or HOCH (R ¹ ) CH ₂ —, and A represents a divalent hydrocarbon group. )

The outermost polymer layer of the above-mentioned multilayer organic fine particles has a polymer layer obtained by using at least 70% by weight of an alkyl (meth) acrylate and / or an aromatic vinyl as a monomer. It preferably comprises

[0007] It is preferable that 70 mol% or more of the total acid component of the carboxyl group-containing polyester resin is isophthalic acid.

Further, an epoxy equivalent of 100 to 1 with respect to 100 parts by weight of the carboxyl group-containing polyester resin.
It is preferable to contain 1 to 20 parts by weight of an epoxy resin having a softening point of 500 and an epoxy group-containing vinyl resin having a softening point of 40 to 150 ° C.

On the other hand, the present invention is a method for applying the above-mentioned thermosetting powder coating composition to an object to be coated as an undercoat.

[0010] The present invention also relates to a design article having a design film on a coating film formed from the thermosetting powder coating composition.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The powder coating composition of the present invention comprises a carboxyl group-containing polyester resin having a specific acid component, an acid value and a softening point, a β-hydroxyalkylamide curing agent, and a multilayer structure having a specific structure. It is a thermosetting powder coating composition containing organic fine particles.

Polyester Resin The carboxyl group-containing polyester resin contained in the thermosetting powder coating composition of the present invention contains an aromatic polycarboxylic acid as a main component as an acid component. The aromatic polycarboxylic acid accounts for 70 mol% or more, preferably 8 mol%, of the total acid components.
It is 0 mol% or more, more preferably 90 mol% or more, and may be 100 mol%. If the proportion of the aromatic polycarboxylic acid in the total acid component is less than 70 mol%, the curability will be reduced, and the mechanical properties and corrosion resistance of the resulting coating film may be reduced.

The carboxyl group-containing polyester resin has an acid value of 10 to 100 (mg KOH).
/ G solid content; the same applies hereinafter), preferably 15 to 80, more preferably 20 to 60. If the acid value is less than 10, curability is reduced, there is a possibility that the mechanical properties of the resulting coating film is reduced,
If it is larger than 100, a large amount of curing agent is required,
Not only is it economically disadvantageous, but also the water resistance and mechanical properties of the resulting coating film may be reduced.

The carboxyl group-containing polyester resin has a softening point of 80 to 150 ° C., preferably 90 to 13 ° C.
It is desirable to be in the range of 0 ° C. The above softening point is 80 ° C
When the temperature is lower, the blocking resistance of the obtained powder coating may decrease, and when it is higher than 150 ° C., the smoothness of the obtained coating film may decrease.

On the other hand, the carboxyl group-containing polyester resin has a number average molecular weight of 1,000 to 20,000, preferably 2,000 to 10,000, more preferably 2,000.
It is desirable to be in the range of 000-6000. When the number average molecular weight is less than 1000, the performance and physical properties of the obtained coating film may be reduced.
If it is larger than 0000, the smoothness and appearance of the obtained coating film may be reduced.

In the present invention, the acid value of the resin solid content is JIS K 0070, and the softening point is JIS K 2207.
Can be determined by methods respectively conforming to the above.
The number average molecular weight in the present invention can be determined by a method well known by those skilled in the art such as gel permeation chromatography (GPC).

The carboxyl group-containing polyester resin may be a composite of two or more types. In that case, the above physical property values and special values mean the values of the composite as a whole.

Such a carboxyl group-containing polyester resin is mainly composed of an acid component containing a polycarboxylic acid as a main component in which the proportion of an aromatic polycarboxylic acid accounts for 70 mol% or more of all the acid components, and a polyhydric alcohol. an alcohol component which is a component can be obtained by polycondensation by an ordinary method as a raw material. By selecting the respective components and the conditions of the polycondensation, a carboxyl group-containing polyester resin having the above-mentioned physical properties and special values can be obtained.

The aromatic polycarboxylic acid component that can be used in the carboxyl group-containing polyester includes:
For example, aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, phthalic acid, and naphthalenedicarboxylic acid, and anhydrides or dimethyl esters thereof can be mentioned. Further, a trivalent or higher aromatic carboxylic acid component such as trimellitic acid or pyromellitic acid can be used together with the aromatic dicarboxylic acid component as long as the polyester resin is not gelled. Other acid components that can be used with the aromatic polycarboxylic acid in the carboxyl group-containing polyester is not particularly limited, for example, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecane dicarboxylic acid, 1,4 -Saturated aliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid and anhydrides and dimethyl esters thereof. The acid component may be of two or more types. Among them, isophthalic acid and terephthalic acid are preferable from the viewpoint of curability, durability, physical properties, and price. The proportion of terephthalic acid and / or isophthalic acid in the total acid components is at least 70 mol%, preferably at least 80 mol%,
Especially preferably, 90 mol% or more is suitable. The total amount of the acid component used for preparing the polyester resin may be terephthalic acid and / or isophthalic acid. When it is desired to particularly improve the weather resistance, the proportion of isophthalic acid in the total acid components is 70 mol% or more, preferably 80 mol%.
Above, particularly preferably 90 mol% or more is suitable.

The alcohol component is not particularly restricted but includes, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,5-hexanediol, diethylene glycol, triethylene glycol, Ethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol,
Bisphenol A alkylene oxide adduct, bisphenol S alkylene oxide adduct, 1,2-propanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 2,3- Pentanediol, 1,4-pentanediol, 1,4-hexanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol,
Diols such as 1,2-dodecanediol and 1,2-octadecanediol, and trimethylolpropane, glycerin,
Examples include trihydric or higher polyhydric alcohols such as pentaerythritol. The alcohol component may be of two or more types. Among them, ethylene glycol and / or neopentyl glycol can be preferably used.

If necessary, lactones such as γ-butyrolactone and ε-caprolactone, and corresponding hydroxycarboxylic acids and aromatic oxymonocarboxylic acids such as p-oxyethoxybenzoic acid can be used. .

Β-hydroxyalkylamide curing agent The β-hydroxyalkylamide curing agent contained in the powder coating composition of the present invention is represented by the following formula.

[0023]

Embedded image

Here, in the formula, R ¹ is a hydrogen atom, a methyl group or an ethyl group, R ² is a hydrogen atom, having 1 to 1 carbon atoms.
5 is an alkyl group or HOCH (R ¹ ) CH ₂ —,
Represents a monovalent hydrocarbon group.

In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² is HOCH (R ¹ ) CH ₂
-, A is preferably an alkylene group having 2 to 10 carbon atoms, more preferably 4 to 8 carbon atoms.

The curing agent can be obtained, for example, by reacting a carboxylic acid and / or a carboxylic acid ester with a β-hydroxyalkylamine in the presence of an alkoxide catalyst such as sodium or potassium.

The carboxylic acid or carboxylic acid ester used here includes, for example, succinic acid, adipic acid, glutaric acid, dimethyl succinate, diethyl succinate, dimethyl adipate and the like.

Examples of the β-hydroxyalkylamine include N-methylethanolamine, diethanolamine, N-methylpropanolamine and the like.

Multilayer organic fine particles The multilayer organic fine particles contained in the thermosetting powder coating composition of the present invention are particles having a structure of two or more layers,
At least one of the inner layers is a crosslinked polymer layer having a glass transition temperature (Tg) of 20 ° C. or less, and the outermost layer is formed of a Tg of 40 ° C. or more and a functional group of at least one of carboxyl, hydroxyl, and epoxy groups. It is a polymer layer having a group. Such multilayer organic fine particles can be obtained by emulsion polymerization including a plurality of stages such as a pre-stage and a post-stage, that is, a multi-stage emulsion polymerization method. Specifically, it can be obtained by continuous multi-stage emulsion polymerization in which monomers in the subsequent stage are sequentially subjected to seed polymerization in the presence of the polymer obtained in the previous stage. This multi-stage emulsion polymerization,
Even if it is divided into two stages before and after the former stage,
It may be divided into two or more stages. Here, when divided into two stages before and after, the former stage is for the inner layer, and the latter stage is for the outer layer. When performing multi-stage emulsion polymerization of two or more stages,
In the present invention, this polymer portion is referred to as the outermost layer because the polymer portion formed by polymerization of the monomer component added to the final polymerization system is located on the surface layer of the multilayer organic fine particles.

The above-mentioned organic fine particles having a multilayer structure comprise a polymer layer having at least one inner layer having a Tg of 20 ° C. or less, preferably 5 ° C. or less. If the temperature exceeds 20 ° C., the effect of improving the mechanical properties of the obtained coating film and the effect of improving the water-resistant secondary adhesion to the substrate may be reduced. Also, if the inner layer is multiple layers,
At least one of the layers may have a Tg of 20 ° C. or less, and all layers may have a Tg of 20 ° C. or less. As described above, the polymer layer having a Tg of 20 ° C. or lower is formed by seed-polymerizing a monomer forming the polymer in the presence of the seed latex or the polymer particles in the previous stage.

Monomers capable of forming a polymer layer having a Tg of 20 ° C. or lower include, for example, conjugated dienes such as butadiene, isoprene, and chloroprene, ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, and isononyl acrylate. , 2
Alkyl acrylates such as -ethylhexyl acrylate; and vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate. Of these, butadiene and butyl acrylate, 2-ethylhexyl acrylate are preferably used. Further, when Tg is in the range of 20 ° C. or lower, monomers copolymerizable therewith, for example, aromatic vinyls such as styrene, vinyltoluene and α-methylstyrene, and vinyl cyanide such as acrylonitrile and methacrylonitrile. , Methyl methacrylate, alkyl methacrylates such as butyl methacrylate, benzyl acrylate, benzyl methacrylate,
Aromatic (meth) acrylates such as phenoxyethyl acrylate can be copolymerized. Among them, styrene, acrylonitrile and methyl methacrylate are preferred.

In the polymerization of the polymer layer having a Tg of 20 ° C. or lower according to the present invention, in addition to the above-mentioned monomers,
It is desirable to use a crosslinkable monomer. The amount of the crosslinkable monomer used is 0.3 to 50% by weight, preferably 0.3% by weight, based on the total weight of the monomers constituting the polymer layer.
It is desirable to use 5 to 40% by weight. If the amount is less than 0.3% by weight, the appearance of the coating film, the pulverizability of the powder coating and the blocking resistance may decrease, and if it exceeds 50% by weight, the effect of improving mechanical properties such as impact resistance may be reduced. It may be difficult to obtain.

The crosslinkable monomer is a monomer having at least two radically polymerizable unsaturated groups in the molecule or a monomer having a functional group capable of reacting with each other and a radically polymerizable unsaturated group. Means

The monomers having at least two radically polymerizable unsaturated groups in the molecule include a polymerizable unsaturated monocarboxylic acid ester of a polyhydric alcohol, a polymerizable unsaturated alcohol ester of a polybasic acid and 2 Aromatic compounds substituted with two or more vinyl groups are exemplified. Examples thereof are ethylene glycol di (meth) acrylate, triethylene glycol di (meth)
Acrylate, tetraethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol (meth) acrylate, neopentyl glycol di (meth) Acrylate,
1,6-hexaneol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethanedi (meth) acrylate , triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate, and allyl (meth) acrylate and divinyl benzene.

A monomer having a functional group capable of reacting with each other and a radically polymerizable unsaturated group is a monomer having two kinds of radically polymerizable unsaturated groups each having a functional group capable of reacting with each other. Means a combination of, glycidyl acrylate, epoxy group-containing ethylenically unsaturated monomer such as glycidyl methacrylate, acrylic acid, methacrylic acid, carboxyl group-containing ethylenically unsaturated monomer such as crotonic acid and There is. Other combinations of functional groups that can react with each other include amino groups and carboxylic acid groups,
There are an epoxy group and a carboxylic acid group or an anhydride thereof,
The above mutually reactive functional groups broadly include these combinations.

Of these, neopentyl glycol diacrylate, butylene glycol diacrylate, hexanediol diacrylate and allyl methacrylate are preferably used.

The organic fine particles having a multilayer structure have Tg in the outermost layer.
Has a polymer layer of 40 ° C. or higher, preferably 60 ° C. or higher. If the Tg of the outermost layer is less than 40 ° C., the blocking resistance of the powder coating may be reduced.

After preparing the latex up to the previous stage as described above, a monomer forming a polymer layer having a Tg of 40 ° C. or higher is subjected to seed polymerization in the presence of the latex to obtain a Tg.
Can form an outermost layer composed of a polymer layer having a temperature of 40 ° C. or higher. The monomer used in the seed polymerization of the outermost layer having a Tg of 40 ° C. or higher may be any monomer capable of forming a polymer having a Tg of 40 ° C. or higher, such as methyl methacrylate, ethyl methacrylate, and cyclohexyl. Alkyl methacrylates such as methacrylate and aromatic vinyls such as styrene can be used. Of these, methyl methacrylate and styrene are preferred. If the Tg is 40 ° C. or higher, monomers copolymerizable therewith, for example, alkyl (meth) acrylates such as ethyl (meth) acrylate and butyl (meth) acrylate, vinyl toluene, α -Aromatic vinyls such as methylstyrene and vinyl cyanides such as acrylonitrile and methacrylonitrile can be copolymerized. In addition, Tg is 20 ° C.
The following crosslinkable monomers for forming the polymer layer may be copolymerized.

[0039] 70 wt% of the monomers forming the outermost layer
Or more, preferably 80% by weight or more, more preferably,
It is particularly desirable that at least 90% by weight be alkyl (meth) acrylates and / or aromatic vinyls.
When the content is less than 70% by weight, the effect of improving the resistance of the obtained powder coating material to acrylic contamination is reduced, and “dents” and “repelling” may occur.

In the above-mentioned organic fine particles having a multilayer structure, it is essential that the polymer layer forming the outermost layer has at least one functional group of a carboxyl group, a hydroxyl group and an epoxy group. The functional group of the polymer layer forming the outermost layer may be one of a carboxyl group, a hydroxyl group, and an epoxy group, or may be a combination of two or more. Among them, a hydroxyl group is particularly preferred. If the polymer layer forming the outermost layer does not have one or more functional groups among carboxyl groups, hydroxyl groups, and epoxy groups, the dispersibility of the multilayer organic fine particles in the polyester resin becomes poor, and the resulting coating is obtained. film hard spots occur or to, which may cause a decrease in reduction, topcoat adhesion improving effect of the acrylic contamination resistance. When the outermost layer has a hydroxyl group, the hydroxyl value of the polymer layer forming the outermost layer is from 1 to 150, preferably,
A range of 2 to 100 is desirable. If the hydroxyl value is less than 1, the resulting coating film may have bumps, lower mechanical properties, lower gloss, and lower water-resistant secondary adhesion. Water-resistant secondary adhesion may be reduced. When the outermost layer has a carboxyl group, the acid value of the polymer layer forming the outermost layer is desirably 1 to 100, preferably 2 to 50. If the acid value is less than 1, the resulting coating film may have bumps, lower mechanical properties, lower gloss, and lower water-resistant secondary adhesion. Water-resistant secondary adhesion may be reduced. When the outermost layer has an epoxy group, the epoxy equivalent of the polymer layer forming the outermost layer is 300 to 5000.
0 g / eq, preferably 500 to 10000 g / eq
Is desirable. If the epoxy equivalent is less than 300, the storage stability of the obtained paint may decrease,
If it exceeds 0000, the resulting coating film may have bumps,
There is a possibility that a decrease in mechanical properties, a decrease in gloss, and a decrease in water-resistant secondary adhesion may occur.

[0041] The outermost layer carboxyl group, a hydroxyl group, one or more functional groups of the epoxy group, a carboxyl group,
It can be obtained by copolymerizing a monomer having at least one functional group among a hydroxyl group and an epoxy group with a monomer capable of forming a polymer layer having a Tg of 40 ° C. or higher. Examples of the monomer having such a functional group include carboxyl group-containing ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, itaconic acid and crotonic acid;
Hydroxyl-containing ethylenically unsaturated monomers such as -hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate; glycidyl (meth) acrylate , Β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexyl acrylate, 3,4-epoxycyclohexyl methacrylate, and other epoxy group-containing ethylenically unsaturated monomers. Among these, as the monomer having a carboxyl group, methacrylic acid, as the monomer having a hydroxyl group, 2-hydroxyethyl methacrylate, as the monomer having an epoxy group,
Glycidyl methacrylate is preferably used. Further, other functional groups may be modified. For example, after the epoxy group is introduced into the outermost layer, if the monocarboxylic acid compound is reacted with a part of the epoxy group, it has both the hydroxyl group formed by this reaction and the remaining unreacted epoxy group. Can be. Or it may have after introducing carboxylic acid groups into the outermost layer, both of the carboxyl groups unreacted formed hydroxyl group and the remainder of this reaction is reacted with monoepoxy compounds.

The polymer layer forming the outermost layer of the above-mentioned organic fine particles having a multilayer structure has at least one functional group selected from a carboxyl group, a hydroxyl group and an epoxy group, and other functional groups such as a sulfonic acid group and a thiol group. It may be contained.

In the above-mentioned organic fine particles having a multilayer structure, the proportion of the polymer layer having a Tg of 20 ° C. or lower is 30 to 95% by weight, preferably 45 to 95% by weight, more preferably 60 to 90% by weight, based on the whole of the multilayer organic fine particles. % Range.
30% by weight of the polymer layer having a Tg of 20 ° C. or less
If the amount is less than the above, the effect of improving the mechanical properties of the obtained coating film may decrease. If the amount exceeds 95% by weight, the blocking resistance, the acrylic mixing resistance and the adhesion of the top coat of the powder coating may decrease. .

The above-mentioned organic fine particles having a multilayer structure can be produced by carrying out multistage emulsion polymerization of two or more stages.
In the final stage, the monomer component for the outermost layer is polymerized, but before that, the monomer component for the inner layer portion may be polymerized in any number of stages. The method of adding the monomer component for the inner layer portion and the outermost layer portion to the polymerization reaction system is not particularly limited, and a method such as batch addition, monomer dropping, and pre-emulsion dropping method may be used for both the first and second stages of polymerization. it can.

In the above-mentioned multi-stage emulsion polymerization, a known one is used as a radical polymerization initiator, but it is not particularly limited. Specifically, ammonium persulfate, sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide,
Persulfates and peroxides such as t-butylperoxybenzoate; 2,2′-azobisisobutyronitrile;
Water-soluble azo compounds such as 2′-azobis (2-amidinopropane) hydrochloride, 2,2′-azobis (2,4-dimethylvaleronitrile), and 4,4′-azobis (4-cyanopentanoic acid) Can be mentioned. The amount used is preferably about 0.1 to 1% by weight of the monomer component. In addition, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, or Rongalite may be combined in order to accelerate the polymerization rate or when polymerizing at a low temperature.

The emulsifier used is not particularly limited, either.
Fatty acid salts such as sodium lauryl sulfate, higher alcohol sulfates, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, alkyl allyl polyether sulfates such as polyoxyethylene alkyl ether sulfate and ammonium polyoxynonylphenyl ether sulfonate Anionic surfactants such as reactive emulsifiers such as polyoxyethylene polyoxypropylene glycol ether sulfate, and monomers having sulfonic acid groups or sulfate groups; polyoxyethylene alkyl ethers and polyoxynonyl phenyl ethers Oxyethylene alkylphenyl, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene-polyoxypropylene block copolymer, reactive nonyl Nonionic surfactants such as emissions surfactants; alkylamine salts, cationic surfactants such as quaternary ammonium salts; (modified) known emulsifier polyvinyl alcohol or the like may be performed in addition.

The above-mentioned emulsifiers can be used alone or in combination of two or more.
It is preferable to use about 01 to 10% by weight. Further, if necessary, t-dodecyl mercaptan, n- octyl mercaptan, n- dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid, may be used a chain transfer agent such as 2-mercaptoethanol. The polymerization temperature is 0 to 100 ° C, preferably 50 to 80 ° C, and the polymerization time is 1 to 15 hours. The emulsion polymerization may be added a hydrophilic solvent and additives.

The weight average particle diameter of the organic fine particles having a multilayer structure thus polymerized is usually 0.1 to 5 μm, preferably 0.2 to 3 μm. If the particle size is less than 0.1 μm, the viscosity of the coating at the time of melting increases, and a good coating appearance may not be obtained. If the particle size is more than 5 μm, the effect of improving mechanical properties and the effect of improving resistance to mixing with acryl are improved. May not be obtained. The particle diameter in the present invention indicates a weight average particle diameter in a latex state at the time of producing multilayer organic fine particles, and is, for example, a dynamic light scattering measurement device (LPA-3000 / LPA-3100 manufactured by Otsuka Electronics Co., Ltd.). ) Can be measured by a dynamic light scattering method.

The multilayer organic fine particles of the present invention can be taken out as fine powder by spray drying the multilayer polymer latex obtained by the above polymerization method using a spray drier. In addition, after once frozen, thawed, and the polymer particles are separated, centrifugal dehydration and drying are performed, and the particles can be taken out as granular flakes or powder.

Coating Composition The thermosetting powder coating composition of the present invention comprises, as main components, the above-mentioned carboxyl group-containing polyester resin, the above β-hydroxyalkylamide curing agent, and the above-mentioned organic fine particles having a multilayer structure. Containing polyester resin 10
0.5 parts by weight of the organic fine particles having a multilayer structure of 0.5 to 0.5 parts by weight.
20 parts by weight, preferably 1 to 10 parts by weight.

When the amount of the organic fine particles having a multilayer structure is less than 0.5 parts by weight, the effect of improving the mechanical properties of the coating film, the effect of improving the resistance to acryl contamination, and the effect of improving the water-resistant secondary adhesion to the substrate are obtained. If the amount exceeds 20 parts by weight, the hardness of the coating film may be reduced and the appearance may be reduced. The reason that the multi-layered organic fine particles improve the acryl mixing resistance is not necessarily clear, but by having the above specific functional group in the outermost layer, it can be uniformly dispersed in the polyester resin. It can be presumed that this contributes to reducing the difference in surface tension of the paint and increasing the viscosity of the paint in the low shear rate region where "dents" and "repulsions" occur, thereby suppressing the appearance failure. . On the other hand, the reason why the water-resistant secondary adhesion with the base material is improved is not always clear, but the internal stress generated in the coating film that has started swelling in contact with water is caused by the above-mentioned multilayer organic fine particles.
It can be presumed that it is alleviated.

The ratio of the number of equivalents of the hydroxyl groups of the β-hydroxyalkylamide curing agent to the number of equivalents of the carboxyl groups of the carboxyl group-containing polyester resin is 0.4 to 1. 3 is preferred. If it is less than 0.4, the amount of the curing agent becomes small, the curing becomes insufficient, and there is a possibility that the mechanical properties of the coating film decrease and the water resistance decreases. When the ratio exceeds 1.3, the amount of the curing agent increases, which is not only economically disadvantageous but also may lower the water resistance of the coating film.

When the acid value of the carboxyl group-containing polyester resin is 10 to 45, the equivalent ratio is 0.6 to 1.3, and more preferably 0.7 to 1.2. preferable. Within this range, the curing reaction proceeds without excess and deficiency, and the mechanical properties and water resistance of the coating film become favorable, which is preferable. On the other hand, when the acid value of the carboxyl group-containing polyester resin is set to 45 to 100, which is higher than the acid value used in ordinary powder coatings, and the low-temperature curability is particularly improved, the above equivalent ratio Is preferably 0.4 to 1.2, more preferably 0.5 to 1.1. Outside this range,
There is a possibility that the mechanical properties and water resistance of the coating film may be reduced.

On the other hand, the thermosetting powder coating composition of the present invention contains the above-mentioned organic fine particles having a multi-layer structure, thereby improving the acrylic mixing resistance, improving the mechanical properties at the time of low-temperature curing, and improving the water resistance of the base material. Adhesion can be improved, but especially for the purpose of further improving low-temperature curability, water-resistant secondary adhesion, oil resistance, and chemical resistance, further containing an epoxy resin and / or an epoxy group-containing vinyl resin. Is also good.

The epoxy resin and the epoxy group-containing vinyl resin have an epoxy equivalent of 100 to 15
00, preferably in the range of 100-1000.
If the epoxy equivalent is less than 100, the storage stability of the coating composition may be reduced. If it exceeds 1500, the low-temperature curability and the effect of improving the adhesion to the substrate may be reduced. Incidentally, the epoxy equivalent of the present invention JIS K
7236. The softening point of the epoxy resin and the epoxy group-containing vinyl resin,
Those having a range of 40 to 150 ° C, preferably 60 to 130 ° C can be used. If the softening point is less than 40 ° C., the blocking resistance of the coating may decrease,
If the temperature exceeds 150 ° C., the smoothness of the obtained coating film may be reduced.

As the above epoxy resin, for example, a resin having an average of 1.1 or more epoxy groups in one molecule is used. Specifically, a reaction product of a novolak type phenol resin and epichlorohydrin, a bisphenol type epoxy resin (A type, B type, F type, etc.), a hydrogenated bisphenol type epoxy resin, a novolak type phenol resin and a bisphenol type epoxy resin ( A type, B type, F type, etc.)
Product of novolak type phenolic resin and bisphenol type epoxy resin (A type,
Reaction products with cresol compounds such as cresol novolak and epichlorohydrin, ethylene glycol, propylene glycol,
Glycidyl ethers obtained by the reaction of epichlorohydrin with alcohol compounds such as 1,4-butanediol, polyethylene glycol, polypropylene glycol, neopentyl glycol and glycerol, succinic acid, adipic acid, sebacic acid, phthalic acid, terephthalic acid, hexa Glycidyl esters obtained by reacting carboxylic acid compounds such as hydrophthalic acid and trimellitic acid with epichlorohydrin, reaction products of hydroxycarboxylic acids such as p-oxybenzoic acid and β-oxynaphthoic acid with epichlorohydrin, 3, 4-epoxy-6
-Methylcyclohexylmethyl-3,4-epoxy-6
Alicyclic epoxy compounds such as -methylcyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl (3,4-epoxycyclohexane) carboxylate, triglycidyl isocyanurate and derivatives thereof. The epoxy resin may be two or more. Examples of such commercially available epoxy resins include Epotote YD-014, ST-5080, and ST-5080.
-5100, ST4100D, YDCN701, (all manufactured by Toto Kasei Co., Ltd.), Denacol EX-711 (manufactured by Nagase Kasei Kogyo Co., Ltd.), Epicron N-680, Epicron N-695, Epicron HP-7200H (all,
Dainippon Ink and Chemicals, Inc.), Araldite PT 81
0, Araldite PT 910 (manufactured by Nippon Ciba Geigy), TEPIC (manufactured by Nissan Chemical Industries) and the like.

The above epoxy group-containing vinyl resin is a vinyl copolymer having an epoxy group at the terminal or side chain of the molecule. The epoxy group-containing vinyl resin is obtained by copolymerizing a vinyl monomer having an epoxy group and, if necessary, other vinyl monomers. Alternatively, it can be obtained by introducing an epoxy group into a vinyl copolymer. First, when the epoxy group-containing vinyl resin is to be obtained by copolymerization, the epoxy group-containing vinyl monomer used therein includes glycidyl (meth) acrylate and β-methylglycidyl (meth) acrylate. Examples include various glycidyl esters of (meth) acrylic acid, and various alicyclic epoxy group-containing vinyl monomers such as 3,4-epoxycyclohexyl acrylate and 3,4-epoxycyclohexyl methacrylate. Examples of the other vinyl monomers include (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, and benzyl (meth) acrylate. , 2-hydroxyethyl (meth) acrylate, 2
-Hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth)
Hydroxyl-containing (meth) acrylates such as acrylates,
Ethylene, propylene, such as butene-1, various α
-Various aromatic vinyl compounds such as olefins, styrene, α-methylstyrene and vinyltoluene, and vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate.

On the other hand, if the latter method, that is, a method of introducing an epoxy group into a vinyl copolymer, is desired,
For example, there is a method of reacting glycidol with a vinyl copolymer having an isocyanate group.

The number-average molecular weight of the epoxy group-containing vinyl resin is preferably 3 from the viewpoint of mechanical properties and smoothness of the coating film.
00 to 5000, preferably 1,000 to 5,000
Is suitable. The epoxy group-containing vinyl resin may be a composite of two or more types. Examples of such commercially available epoxy group-containing vinyl polymers include Finedick A207S and Finedick A223.
S, Fine Dick A224S, Fine Dick A
229, FineDick A229-30, FineDick A229-30A, FineDick A54-3
88, Fine Dick A56-200S, Fine Dick A241, Fine Dick A244A, Fine Dick A247S, Fine Dick A249A
(All are products of Dainippon Ink and Chemicals, Inc.), Armatex PD-6100, Armatex PD-620
0, Armatex PD-6300, Armatex P
D-6400, Armatex PD-6600, Armatex PD-6640, Armatex PD-, Armatex PD-6710, Armatex PD-67
30, Armatex PD-7110, Armatex PD-7210, Armatex PD-7610, Armatex PD-7690 (all manufactured by Mitsui Chemicals, Inc.) and the like.

The thermosetting powder coating composition of the present invention comprises 0.1 to 20 parts by weight of the epoxy resin and / or the vinyl resin having the epoxy group per 100 parts by weight of the carboxyl group-containing polyester resin. ,Preferably,
0.5 to 15 parts by weight, more preferably 0.5 to 10 parts by weight, may be contained. And adhesion improving effect of the base material of the epoxy resin and / or epoxy group-containing vinyl coating resins were obtained is less than 0.1 part by weight film, low-temperature curability, oil resistance, chemical resistance There is a possibility that the improvement effect may be reduced, and if it exceeds 20 parts by weight, the solid phase reaction of the coating may proceed and storage stability may be reduced.

The thermosetting powder coating composition of the present invention may contain, if necessary, various additives such as a surface conditioner, a curing catalyst, a plasticizer, an ultraviolet absorber, an antioxidant, an anti-sticking agent and a charge controlling agent. May be included.

In particular, as the surface conditioner, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) ) A number average molecular weight obtained from alkyl esters of (meth) acrylic acid such as acrylate as a raw material is 300 to 50,000, preferably 1,000 to 3,000.
0, the glass transition temperature is less than 20 ° C., preferably 0 ° C.
Those made of the following acrylic polymers are preferred. When the molecular weight is out of the above range, sufficient surface adjustability cannot be imparted, and insufficient appearance prevention such as dents becomes insufficient. Further, when the glass transition temperature is 20 ° C. or higher, there is a possibility that sufficient surface adjustability cannot be provided.

The above-mentioned surface conditioner is contained in the powder coating composition in an amount of 0.01 to 5% by weight, preferably 0.05 to 3% by weight, more preferably 0.1 to 2% by weight. Is preferred. Probability of poor appearance can not be imparted sufficiently surface adjustability less than 0.01 wt% becomes high, more than 5 wt%, blocking resistance of the coating may be decreased.

Commercially available such surface conditioners include, for example, Acronal 4F as an acrylic polymer.
(Manufactured by BASF), Polyflow S (manufactured by Kyoeisha Chemical),
Residflow LV (manufactured by ESTRON CHEMICAL) and the like, and examples of silica-supported acrylic polymers include Modaflow III (manufactured by Monsanto) and Residflow P67 (manufactured by ESTRON CHEMICAL).
Such as is preferably used. Further, a mixture of an acrylic polymer and an epoxy resin as a surface conditioner may be used such that the amount of the epoxy resin used falls within the above range.

Other surface conditioners include fluorinated polymers such as esters of polyethylene glycol or polypropylene glycol with fluorinated fatty acids, for example, esters of polyethylene glycol with a molecular weight greater than about 2500 and perfluorooctanoic acid, High molecular weight siloxanes having a molecular weight of more than 1000, for example,
Polydimethylsiloxane or poly (methylphenyl) siloxane can also be used.

The thermosetting powder coating composition of the present invention can obtain a transparent coating film without adding a pigment, or
Pigments can also be added. The pigment is not particularly limited, and specifically, titanium dioxide, red iron oxide, yellow iron oxide, carbon black, phthalocyanine blue,
Color pigments such as phthalocyanine green, quinacridone pigments and azo pigments, metallic pigments of each color, pearl pigments of each color, metal powders and surface-treated ones, talc, silica, calcium carbonate, precipitated barium sulfate, etc. Pigments and the like can be mentioned. Further, in order to reduce the gloss, an inorganic matting agent such as talc, silica, calcium carbonate, barium sulfate, feldspar, wollastonite and the like, and an organic matting agent composed of organic fine particles can be contained. The volume average particle diameter of the matting agent is 3 to 3
It is preferably 0 μm. Further, the thermosetting powder coating composition of the present invention may be to improve the corrosion resistance, tripolyphosphate aluminum pigment whose surface is treated, calcium-modified silicate pigment, it may be added anticorrosive pigments such as zinc molybdate .

The production of the thermosetting powder coating composition of the present invention can be carried out using a production method well known in the field of powder coating. For example, the carboxyl group-containing polyester resin, the β-hydroxyalkylamide curing agent, and the organic fine particles having a multilayer structure as essential, the other epoxy resin, the epoxy group-containing vinyl resin,
After preparing the material such as the pigment and the additives,
The raw materials are preliminarily mixed using a super mixer, a Hensiel mixer or the like, and the raw materials are melted and kneaded using a kneader such as a co-kneader or an extruder. The heating temperature at this time must be lower than the bake hardening temperature, but it must be a temperature at which at least a part of the raw material can be melted and kneaded as a whole. Generally it is melt-kneaded in the range of 80 to 120 ° C.. Next, the melt is solidified by cooling with a cooling roll, a cooling conveyor, or the like, and is pulverized to a desired particle size through coarse pulverization and fine pulverization steps.

The thus obtained thermosetting powder coating composition of the present invention preferably has a volume average particle diameter of 5 to 50 μm, and is used to adjust the particle size distribution by removing giant particles and fine particles. It is preferable to perform classification by sieving. When used for thin film coating or three-dimensional structure coating, the volume average particle diameter is preferably 5 to 40 μm. Particularly when a thin and smooth coating film is to be obtained, 5 to 30
μm is preferred. The volume average particle size is measured by a particle size analyzer (for example, Microtrack HRA manufactured by Nikkiso Co., Ltd.).
X-100).

Further, a fluidity-imparting agent or a charge controlling agent may be externally added to the surface of the powder coating obtained by the above-mentioned production method. The fluidity-imparting agent not only imparts fluidity to the powder coating material itself, but also can improve blocking resistance. As the fluidizing agent, hydrophobic silica,
Hydrophilic silica, aluminum oxide, titanium oxide, and the like can be used. Such commercially available fluidity-imparting agents include, for example, AEROSIL130, AEROSIL20
0, AEROSIL 300, AEROSILR-97
2, AEROSIL R-812, AEROSIL R
-812S, titanium dioxide T-805, titanium dioxide P
-25, Aluminum OxideC (manufactured by Nippon Aerosil Co., Ltd.), Carplex FPS-1 (manufactured by Shionogi & Co., Ltd.) and the like. The amount of the fluidity-imparting agent to be added is 0.05 to 2 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of the powder coating, from the viewpoint of the effect to be imparted and the smoothness of the coating film. Parts by weight are preferred. If the amount is less than 0.05 part by weight, the effect is small, and if it exceeds 2 parts by weight, there is a possibility that the smoothness of the coating film is reduced and gloss is generated.

The thermosetting powder coating composition of the present invention can be applied to an object to be coated and then heated to obtain a coating film. The object to be coated is not particularly limited, and specific examples thereof include an iron plate, a steel plate, an aluminum plate, and the like, and a surface-treated one thereof.
Film formation of the object to be coated is also a single layer made of a thermosetting powder coating composition of the present invention have good protection,
Multiple layers may be formed. In this case, the thermosetting powder coating composition may be directly applied to the object to be coated as an undercoating paint, that is, a primer to form an undercoating film, and an intermediate coating and a topcoating may be applied thereon. . Further, the object to be coated may be already undercoated or the like, and the powder coating composition may be applied as an intermediate coating or a top coating on the undercoat film. As the undercoat paint for forming the undercoat, known paints such as an electrodeposition paint and a primer can be used. In particular, as a preferred multilayer film form, the thermosetting powder coating composition is directly applied as a primer or a primer on an object to be coated that is weak to heat, such as an aluminum wheel, and has a low baking temperature,
For example the undercoating film is formed by 140 to 160 ° C., then painting the top coating, may form a multi-layer film, coating the thermosetting powder coating composition as a primer, then, A top coat may be applied to form a multilayer film at a time with a low baking temperature.

The coating method is not particularly limited, and a method well-known to those skilled in the art such as a spray coating method, an electrostatic powder coating method, an electric fluidization method, and a fluid immersion method can be used. From the viewpoint of coating efficiency, an electrostatic powder coating method is preferably used.

The thickness of the coating when the thermosetting powder coating composition of the present invention is applied is not particularly limited.
μm can be set.

The heating conditions vary depending on the amount of functional groups involved in curing and the like. For example, the heating temperature is 120 to 25.
0 ° C., preferably 130-210 ° C., particularly preferably
The heating temperature is 140 ° C. to 180 ° C., and the heating time can be appropriately set according to the heating temperature.

On the other hand, the present invention relates to a design in which a design comprising required characters, patterns, irregularities, colors and the like is formed on a coating film made of the above-mentioned thermosetting powder coating composition by printing, coating, sticking or the like. Can have a conductive film. The design composed of characters, patterns, irregularities, colors, etc. is, for example, a coating film composed of the above-mentioned thermosetting powder coating composition by ink, paint, etc., by letterpress printing, intaglio printing, lithographic printing, stencil printing, screen printing, etc. By partially printing on the substrate and drying using a known technique such as air drying, heat curing, and light curing. In addition, a non-coated surface is coated on the coating film made of the thermosetting powder coating composition using a masking member, or without coating, partially applying a solvent-based coating or a water-based coating, It can be obtained by drying. As the coating method, a known method, for example, spray coating, brush coating, or the like can be used. Further, a marking film made of a film or a transfer sheet may be thermally transferred or pressed onto a coating film made of the thermosetting powder coating composition. The design formed by the above method, which includes characters, patterns, irregularities, colors, and the like, may be further formed with a clear film for the purpose of protection.

Since the coating of the thermosetting powder coating composition has good top coat adhesion, the article having the above-mentioned design film can have a long-term design property.
Specific examples of the above-mentioned articles include building materials such as gates and fences, road materials such as guardrails and poles, building interior and exterior materials such as window frames and slate, automobile bodies or automobile parts, and automatic sales. equipment such as aircraft, billboards, goods or to be used outdoors, such as labeling, metal products such as steel furniture, refrigerators, household appliances such as washing machines, like the article or the like to be used indoors, such as .

[0076]

EXAMPLES The present invention will be described in detail with reference to production examples and examples of the present invention, but the present invention is not limited to these examples.

Production Example 1 Polyester containing a carboxyl group
Preparation of Resin A1 In a reaction vessel equipped with a stirrer, thermometer, condenser and nitrogen gas inlet, ethylene glycol: 180 parts by weight (2.91 mol), neopentyl glycol: 1715
Parts by weight (16.49 mol), dimethyl terephthalate:
A mixture consisting of 1746 parts by weight (9.0 mol), adipic acid: 146 parts by weight (1.0 mol) and 1.5 parts of zinc acetate is heated in a stream of nitrogen to form at 160 ° C. for 1 hour. While removing methanol outside the reaction system, the temperature was gradually raised, and an alcohol exchange reaction was performed at 210 ° C. for 2 hours. Next, here, 996 parts by weight of terephthalic acid (6.0 mol) and 664 parts by weight of isophthalic acid (4.0 mol) were further added.
Mol) and 2 parts of di-n-butyltin oxide, the mixture was gradually heated to 240 ° C., and an esterification reaction was carried out while distilling off generated water, whereby the acid value was reduced. At 33, the desired carboxyl group-containing polyester resin A1 having a softening point of 109 ° C. was obtained.

Production Example 2 Polyester containing carboxyl group
Preparation of Resin A2 Neopentyl glycol: 1946 in a reaction vessel equipped with a stirrer, thermometer, condenser and nitrogen gas inlet.
Parts by weight (18.71 mol), trimethylolpropane:
92 parts by weight (0.69 mol), isophthalic acid: 3320
A mixture consisting of 2 parts by weight (20.0 mol) and 2 parts of di-n-butyltin oxide was heated in a stream of nitrogen to give 24 parts.
While gradually raising the temperature to 0 ° C. and distilling off the generated water,
By carrying out the esterification reaction, an intended carboxyl group-containing polyester resin A2 having an acid value of 34 and a softening point of 112 ° C. was obtained.

Production Example 3 Polyester containing a carboxyl group
Preparation of Resin A3 Ethylene glycol: 208 parts by weight (3.35 mol), neopentyl glycol: 1037 in a reaction vessel equipped with a stirrer, thermometer, condenser and nitrogen gas inlet.
Parts by weight (9.97 mol), 1,4-cyclohexanedimethanol: 518 parts by weight (3.60 mol), dimethyl terephthalate: 2067 parts by weight (11.0 mol) and a mixture of 1.5 parts of zinc acetate Was heated in a nitrogen stream, and the temperature was gradually raised at 160 ° C. for 1 hour while removing generated methanol outside the reaction system, and an alcohol exchange reaction was performed at 210 ° C. for 2 hours. Next, a mixture consisting of 1551 parts by weight (9.0 mol) of terephthalic acid, 145 parts by weight (1.08 mol) of trimethylolpropane and 2 parts of di-n-butyltin oxide was further charged. The temperature was raised to 240 ° C., and the esterification reaction was carried out while distilling off the generated water.
Thus, a target carboxyl group-containing polyester resin A3 having a softening point of 105 ° C. was obtained.

Production Example 4 Preparation of Multilayered Organic Fine Particles B1 In a reaction vessel equipped with a stirrer, thermometer, condenser and nitrogen gas inlet, 421.7 parts of ion-exchanged water, Neocol P (Daiichi Kogyo Seiyaku Co., Ltd. Of 1% aqueous solution of 1% aqueous sodium hydrogencarbonate, and the mixture was heated to 70 ° C. while stirring under a nitrogen stream.
After the temperature was raised, 6.7 parts of ethyl acrylate was added, and the mixture was stirred for 10 minutes. Then, 3.4 parts of a 2% aqueous sodium persulfate solution was added, and the mixture was further stirred for 1 hour to obtain a seed latex. Subsequently, at 70 ° C., 42.5 parts of a 2% aqueous sodium persulfate solution was added, and then 526.4 parts of n-butyl acrylate, 11.2 parts of 1,4-butylene glycol diacrylate, and 22.4 parts of allyl methacrylate.
340 parts of a 1% aqueous solution of Neocol P, and 56.7 parts of a 1% aqueous solution of sodium bicarbonate, a monomer emulsion for forming an inner layer was added dropwise over 240 minutes. After the completion of the dropwise addition, the mixture was further stirred at 70 ° C. for 60 minutes to perform an aging reaction. Next, 6 parts of a 2% aqueous sodium persulfate solution was added while maintaining the temperature at 70 ° C., and then 82 parts of methyl methacrylate, 10 parts of ethyl acrylate, 1 part of 1,4-butylene glycol diacrylate, and 2-hydroxyethyl methacrylate 7 A monomer emulsion for forming an outermost layer consisting of 0.0 part, 40 parts of a 1% aqueous solution of Neocol P and 10 parts of a 1% aqueous solution of sodium hydrogen carbonate was added dropwise over 150 minutes. After dropping,
The temperature was raised to 80 ° C., and the mixture was further stirred for 60 minutes to perform an aging reaction. After completion of the aging reaction, the mixture was cooled to 30 ° C. and filtered through a 300-mesh stainless steel wire mesh to obtain a latex of multilayer organic fine particles B1 having a weight average particle diameter of 0.48 μm. This latex is frozen at -30 ° C once,
After thawing, dehydration washing was performed by a centrifugal dehydrator, followed by blast drying at 60 ° C for 24 hours, and then crushed to obtain multilayer organic fine particles B1.
I got The hydroxyl value of the outermost layer was 29 when calculated from the monomer mixture, and the Tg was -45 ° C for the inner layer and 89 ° C for the outermost layer when calculated from the monomer mixture.

Production Example 5 Preparation of Multilayered Organic Fine Particles B2 The monomer emulsion for forming the outermost layer of Production Example 4 was prepared by adding 84 parts of methyl methacrylate, 10 parts of ethyl acrylate, 1,4
-Multi-layer organic fine particles B2 were obtained in the same manner as in Production Example 4, except that 1 part of butylene glycol diacrylate, 5 parts of methacrylic acid, 1 part of an aqueous solution of 1% neochol P were changed to 10 parts of an aqueous solution of 1% sodium hydrogen carbonate. . The multilayer organic fine particles B2 had a weight average particle diameter of 0.50 μm. The acid value of the outermost layer is 3
Tg was also calculated from the monomer formulation, and found to be -45 ° C for the inner layer and 96 ° C for the outermost layer.

Production Example 6 Preparation of Multilayered Organic Fine Particles B3 The monomer emulsion for forming the outermost layer of Production Example 4 was prepared by adding 82 parts of methyl methacrylate, 10 parts of ethyl acrylate, 1,4
Butylene glycol diacrylate 1 part, glycidyl methacrylate 7 parts, 1% neocor P aqueous solution 40 parts, 1 part
The same procedure as in Production Example 4 was carried out, except that the aqueous solution was changed to 10 parts of a 10% aqueous sodium hydrogencarbonate solution, to obtain multilayer organic fine particles B3.
The multilayer organic fine particles B3 have a weight average particle diameter of 0.4.
It was 9 μm. The epoxy equivalent of the outermost layer was 2029 when calculated from the monomer mixture, and the Tg was -45 ° C for the inner layer and 86 ° C for the outermost layer when calculated from the monomer mixture.

Production Example 7 Preparation of Multilayered Organic Fine Particles B4 89 parts of methyl methacrylate, 10 parts of ethyl acrylate, 1,4
Butylene glycol diacrylate 1 part, 1% neochol P aqueous solution 40 parts, 1% sodium hydrogen carbonate aqueous solution 10
The same procedure as in Production Example 4 was carried out except that the number of parts was changed to obtain organic fine particles B4 having a multilayer structure. The multilayer organic fine particles B4 are
The weight average particle diameter was 0.53 μm. The outermost layer did not have a specific functional group, and the Tg was -45 ° C and the outermost layer was 92 ° C, as calculated from the monomer composition.

Example 1 A carboxyl group-containing polyester resin A1 (acid value: 33,
(Softening point 109 ° C) 100 parts by weight and Primid XL552
(EMS-PRIMD Co., substance represented by β- hydroxyalkylamide curing agent by the following equation, hydroxyl equivalent 8
4) 5 parts by weight of the multilayer organic fine particles B1 (T of the outermost layer)
g 89 ° C., hydroxyl value 24, particle size 0.48 μm) 3 parts, Acronal 4F (manufactured by BASF, acrylic polymer, Tg is −55 ° C., solubility parameter SP is 9.3,
Mixer super mixer using 0.5 parts by weight of a surface conditioner having a number average molecular weight of 16500), 1 part by weight of benzoin, and 65 parts by weight of Taipaque CR-90 (a rutile type titanium dioxide pigment manufactured by Ishihara Sangyo Co., Ltd.) as raw materials. The mixture was mixed for about 3 minutes using a Nippon Spindle Co., Ltd., and was further melt-kneaded at about 110 ° C. using a melt kneader Conneader (manufactured by Bus).

[0085]

Embedded image

Then, after cooling the obtained melt-kneaded product to room temperature, it was pulverized using a pulverizer atomizer (manufactured by Fuji Paudal Co.), and the obtained powder was subjected to an airflow classifier DS-2 (Nippon New Japan). (Matic Industrial Co., Ltd.) to remove fine particles and coarse particles to obtain a powder coating composition. Its volume average particle size was 35 μm. The powder coating thus produced is electrostatically spray-coated on a 0.8 mm zinc phosphate treated steel sheet by a corona charging type coating gun so as to have a film thickness of about 60 μm, and baked at 150 ° C. for 20 minutes. The coating film performance was evaluated by the following methods. Table 2 shows the results.

<Evaluation of Appearance> The appearance of the coating film was measured according to JIS K5.
400 7.1, the 60 ° gloss reflectance of the coating
It measured according to JISK54007.6.

<Evaluation of Impact Resistance> JIS K5400
Using a DuPont method in accordance with 8.3.2, the height of the weight of the coating film at which cracking and peeling occurred was examined under the following conditions.

Weight: 500 g Shot type and cradle size: 1/2 inch <Erichsen value> Cracking of the coating film generated when a test piece is deformed using an Erichsen testing machine in accordance with JIS K5400 8.2.2. -Calculated from the extrusion distance until peeling occurred.

<Evaluation of Water Resistance> JIS K5400
After immersion in boiling deionized water according to 8.20 for 1 hour, 1 m according to JIS K5400 8.5.2.
The number of remaining m-spaced tapes was determined by a stripping tape method.

<Evaluation of Accelerated Weathering Resistance> JIS K5400
According to 9.8.1, 6 hours before and after the 300 hour test
The 0 ° gloss reflectance was measured, and the gloss retention was calculated.

<Evaluation of Adhesion of Topcoat> A topcoat (Super Lac 100, a thermosetting acrylic resin-based paint manufactured by Nippon Paint Co., Ltd.) was applied on the obtained coating film to a thickness of about 30 μm after drying. Dry for 15 minutes. Thereafter, the number of remaining pieces at a distance of 1 mm by a stripping tape method was examined.

<Evaluation of Storage Stability> After the obtained powder coating composition was stored at a constant temperature of 40 ° C. for one month, the initial coating composition and the stored coating composition were each the same as in Example 1. After coating and observing the difference in appearance of the obtained coating film, those having no difference were regarded as good, and those having a difference were regarded as bad.

<Evaluation of Acrylic Contamination Resistance> To 1000 parts of the obtained powder coating composition was added 1 part of an acrylic resin-based powder coating powder Powder A100 (manufactured by Nippon Paint Co., Ltd.). painted in the same manner as in example 1 to the steel sheet, and evaluated the appearance of the resulting coating film, "dents",
Those with "repelling" were regarded as defective.

Examples 2 to 7 and Comparative Examples 1 to 4 Thermosetting powder coatings were prepared and evaluated in the same manner as in Example 1 except that the composition was changed as shown in Table 1. Table 2 shows the results.

[0096]

[Table 1]

[0097]

[Table 2]

Example 8 Instead of the steel sheet treated with zinc phosphate, the powder coating obtained in Example 7 was applied to a chemical conversion-treated aluminum wheel to a thickness of about 100 μm.
m was applied by electrostatic spraying using a corona charging type coating gun, and baked at 150 ° C. for 20 minutes to form a primer coating on the aluminum wheel. Next, a solvent-type base paint (trade name: Superlac 5000 Silver, manufactured by Nippon Paint Co., Ltd.) was spray-coated on the primer coating film so that the film thickness after drying became 20 μm.
After baking at 0 ° C for 15 minutes, a solvent-type clear paint (trade name: Superlac 5000 Clear, manufactured by Nippon Paint Co., Ltd.) was further spray-coated thereon so that the film thickness after drying was 30 µm, and 140 ° C x After baking for 20 minutes, a multilayer coating film composed of a primer coating film, a top coating film and a clear coating film was formed. The coated aluminum wheel obtained here does not deteriorate due to heat during baking, and the primer coating coats the unevenness due to the blasting of the aluminum wheel material, resulting in a smooth finish, adhesion to the overcoat, chipping resistance , Impact resistance and secondary adhesion to water were also good.

As can be seen from the results of the examples, weather resistance,
Without lowering the storage stability, it was possible to obtain higher acrylic mixing resistance, mechanical properties at the time of low-temperature curing, water-resistant secondary adhesion to the substrate, and topcoat adhesion than before.

[0100]

The thermosetting powder coating composition of the present invention comprises a polyester resin having a specific acid value, a softening point and an acid component, a β-hydroxyalkylamide curing agent, a specific structure and a specific functional group. Because it is obtained by blending the organic fine particles having a multilayer structure in a specific ratio, the storage stability of the paint, the low-temperature curability, the adhesion of the top coat, and the resistance to acrylic contamination without lowering the weather resistance In addition, mechanical properties and water-resistant adhesion to a substrate can be significantly improved. On the other hand, the thermosetting powder coating composition of the present invention has excellent low-temperature curability and excellent topcoat adhesion, and is therefore suitable as a basecoat paint.

Continuation of the front page F term (reference) 4J038 CA022 CC012 CF022 CG142 DB002 DB212 DD001 DD061 GA03 GA06 GA07 JA02 JB14 KA03 KA06 MA03 MA13 MA14 NA04 NA11 NA12 PB03 PB05 PB07 PC02

Claims (6)

[Claims] A powder coating composition comprising a carboxyl group-containing polyester resin, a β-hydroxyalkylamide curing agent represented by the following formula, and organic fine particles having a multilayer structure, wherein the carboxyl group-containing polyester resin comprises 70% by mole or more of the acid component is an aromatic polycarboxylic acid, the resin solid content of the acid value is 10 to 100, the softening point of the resin is 80 to 150 ° C, and the weight average of the multilayer organic fine particles. The particle size is 0.1 to 5 μm, and at least one of the inner layers is a crosslinked polymer layer having a glass transition temperature (Tg) of 20 ° C. or lower, and the outermost layer is a polymer layer of Tg of 40 ° C. or higher. And at least one functional group among carboxyl group, hydroxyl group and epoxy group, and the carboxyl group-containing polyester resin 1
The organic fine particles having a multilayer structure of 0.5 to
A thermosetting powder coating composition comprising 20 parts by weight. Embedded image (Wherein R ¹ is a hydrogen atom, a methyl group or an ethyl group,
R ² represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or HOCH (R ¹ ) CH ₂ —, and A represents a divalent hydrocarbon group. ) 2. The polymer layer as the outermost layer of the organic fine particles having a multilayer structure, wherein 70% by weight or more of the polymer layer is obtained by using an alkyl (meth) acrylate and / or an aromatic vinyl as a monomer. The thermosetting powder coating composition according to claim 1, comprising: 3. The thermosetting powder coating composition according to claim 1, wherein 70% by mole or more of the total acid component of the carboxyl group-containing polyester resin is isophthalic acid. 4. An epoxy equivalent of 100 to 1 with respect to 100 parts by weight of the carboxyl group-containing polyester resin.
The thermosetting powder coating composition according to any one of claims 1 to 3, further comprising 1 to 20 parts by weight of an epoxy resin having a softening point of 40 to 150 ° C and / or an epoxy group-containing vinyl resin. 5. A method for applying the thermosetting powder coating composition according to any one of claims 1 to 4 to a substrate as an undercoat. 6. A design article having a design film on a coating film formed from the thermosetting powder coating composition according to any one of claims 1 to 4.