JP2018199778A - Powder coating composition - Google Patents

Abstract

To provide a powder coating composition that can form a matte coating film excellent in finish quality, coating hardness, weather resistance and base material adhesion.SOLUTION: A powder coating composition contains a binder component containing a hydroxy group-containing fluorine resin (A), a polyester resin (B) with an acid value of 10 mgKOH/g or less and a hydroxyl value 10-100 mgKOH/g, and blocked polyisocyanate (C), acrylic fine particles (D) with a volume average particle size 21-45 μm, and a coloring pigment (E). Relative to the 100 pts.mass of the total solid content of the binder component, the content of component (A) is 20-55 pts.mass, the content of component (B) is 20-55 pts.mass, the content of component (C) is 10-40 pts.mass, the content of acrylic fine particles (D) is 1-40 pts.mass, and the content of coloring pigment (E) is 0.5-100 pts.mass.SELECTED DRAWING: None

Description

  The present invention relates to a powder coating composition that is excellent in finish, coating film hardness, weather resistance, and adhesion, and that provides a matte coating film.

  In recent years, there is a growing demand for powder coatings that can replace organic solvent-based coatings in the paint industry and that do not contain volatile organic compounds at all and that do not require exhaust treatment or wastewater treatment and can be recovered and reused. .

  For example, Patent Document 1 discloses a matte powder containing (A) a fluororesin, (B) a polyester resin, (C) a pigment, (D) a crosslinked resin particle, (E) an epoxy resin, and (F) an isocyanate compound. A coating composition is disclosed. Further, it is disclosed that a matte coating film or a coating film having excellent finish is obtained by using the (D) crosslinked resin particles. However, although the matte coating film obtained from the powder coating composition described in Patent Document 1 is excellent in adhesion to the substrate, it may have insufficient weather resistance. Moreover, the matte coating film obtained from the said powder coating composition may produce the skin.

  In addition, Patent Document 2 discloses a powder coating composition containing (A) a fluororesin, (B) a polyester resin, (C) a pigment, and (D) core-shell type acrylic resin particles having functional groups on the surface. Things are disclosed. However, with the powder coating composition described in Patent Document 2, it was not possible to obtain a matte coating film with good finish without any crushed skin. From such a background, there has been a demand for a powder coating composition capable of forming a matte coating film excellent in finish, coating film hardness, weather resistance, and adhesion to a substrate.

JP 2012-41383 A JP 2013-76019 A

  The problem to be solved by the invention is to find a powder coating composition that is excellent in finish, coating film hardness, weather resistance and adhesion, and can form a matte coating film, and to provide a coated article having excellent coating film performance. Is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have found that a hydroxyl group-containing fluororesin (A), a polyester resin (B) having an acid value of 10 mgKOH / g or less and a hydroxyl value of 10 to 100 mgKOH / g, and blocking. It has been found that the problem can be solved by a powder coating composition containing a binder component containing polyisocyanate (C), acrylic fine particles (D) having a volume average particle diameter of 21 to 45 μm, and a color pigment (E). It came to be completed.

That is, the present invention relates to the following aspects.
Item 1. A binder component containing a hydroxyl group-containing fluororesin (A), a polyester resin (B) having an acid value of 10 mgKOH / g or less and a hydroxyl value of 10 to 100 mgKOH / g, and a blocked polyisocyanate (C), having a volume average particle size of 21 to 45 μm A powder coating composition containing acrylic fine particles (D) and a color pigment (E), wherein 20 to 55 parts by mass of component (A) is added to 100 parts by mass of the solid content of the binder component. 20 to 55 parts by mass of (B), 10 to 40 parts by mass of component (C), 1 to 40 parts by mass of acrylic fine particles (D), and 0.5 to 100 parts by mass of color pigment (E). A powder coating composition characterized by the above.
Item 2. Item 2. The powder coating composition according to Item 1, wherein the volume average particle diameter of the acrylic fine particles (D) is 25 to 40 µm.
Item 3. Barium sulfate having a volume average particle size of 0.1 to 20 μm is added to 100 parts by mass of the solid content of the binder component including the hydroxyl group-containing fluororesin (A), the polyester resin (B) and the blocked polyisocyanate (C). Item 3. The powder coating composition according to Item 1 or 2, which contains 1 to 50 parts by mass.
Item 4. Item 4. A coated article having a 60 ° specular glossiness of 50 or less obtained by coating the powder coating composition according to any one of Items 1 to 3.
Item 5. Item 4. A coated article having a coating film having a 60-degree specular gloss of 50 or less, comprising a cured product of the powder coating composition according to any one of items 1 to 3.

  The powder coating composition of the present invention is a coated article having excellent finish, coating film hardness, weather resistance and adhesion, and a matte coating film having a 60 ° specular gloss of 50 or less, preferably 30 or less. Can be provided.

  The powder coating composition of the present invention includes a binder containing a hydroxyl group-containing fluororesin (A), a polyester resin (B) having an acid value of 10 mgKOH / g or less and a hydroxyl value of 10 to 100 mgKOH / g, and a blocked polyisocyanate (C). Ingredients, acrylic fine particles (D) having a volume average particle diameter of 21 to 45 μm and a color pigment (E) are contained. Details will be described below.

[Powder Coating Composition of the Present Invention]
Hydroxyl group-containing fluororesin (A)
The hydroxyl group-containing fluororesin (A) (hereinafter sometimes referred to as “component (A)”) is a polymer having polymerized units based on fluoroolefin. As the component (A), various hydroxyl group-containing fluororesins known for coatings can be used. The hydroxyl group-containing fluororesin (A) may be a copolymer of a fluoroolefin and a monomer having a hydroxyl group, but in addition to a polymer unit based on the fluoroolefin and the monomer having a hydroxyl group, a monomer capable of copolymerization with these monomers. It may be a copolymer containing polymerized units based on the body.

  The hydroxyl group-containing fluororesin (A) can form a cross-linked bond by a reaction between the hydroxyl group contained in the resin and the blocked polyisocyanate (C). The hydroxyl group-containing fluororesin (A) may have groups such as a thiol group, a carboxyl group, an amino group, an amide group, an epoxy group, an isocyanate group, and an allyl group in addition to the hydroxyl group.

  The hydroxyl value of the hydroxyl group-containing fluororesin (A) is 10 to 200 mgKOH / g, preferably 20 to 150 mgKOH / g, and the number average molecular weight is 1,000 to 30,000, preferably 3,000 to 15,000. desirable.

  1 type may be used for a hydroxyl-containing fluororesin (A), and 2 or more types may be used together. In the case where the hydroxyl group-containing fluororesin (A) is a mixture of two or more, the hydroxyl value and the number average molecular weight of each fluororesin constituting the mixture are within the above ranges for finishing and weather resistance. Is preferable.

  In addition, in this specification, a number average molecular weight is the value which converted the number average molecular weight measured using the gel permeation chromatograph (GPC) on the basis of the molecular weight of a standard polystyrene. Specifically, in the measurement of gel permeation chromatograph, “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) is used, and “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G” are used as columns. -2500HXL "and" TSKgel G-2000HXL "(trade name, manufactured by Tosoh Corporation), measurement is performed under the conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C, flow rate 1 mL / min, and detector RI. be able to.

  The hydroxyl group-containing fluororesin (A) in the present invention is a fluorine-containing copolymer containing a polymer unit based on a fluoroolefin and a polymer unit based on a monomer having a hydroxyl group.

  Examples of the fluoroolefin include tetrafluoroethylene, vinylidene fluoride, chlorotrifluoroethylene, trifluoroethylene, hexafluoropropylene, and pentafluoropropylene. 1 type may be used for a fluoro olefin and 2 or more types may be used for it.

  The content of polymerized units based on fluoroolefin in the hydroxyl group-containing fluororesin (A) is preferably 30 to 70 mol% with respect to all polymerized units.

  Examples of the monomer having a hydroxyl group include allyl alcohol, 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxycyclohexyl vinyl ether, 2-hydroxyethyl allyl ether, 3-hydroxypropyl allyl ether, 4-hydroxybutyl allyl ether, 4-hydroxycyclohexyl allyl ether, 2-hydroxyethyl (meth) acrylate, (meth) acrylic acid, maleic anhydride, vinyl hydroxyacetate, vinyl hydroxyisobutyrate, vinyl hydroxypropionate, vinyl hydroxybutyrate , Vinyl esters of hydroxy-substituted fatty acids such as vinyl hydroxyvalerate and vinyl 4-hydroxycyclohexylcarboxylate Door can be.

  In the hydroxyl group-containing fluororesin (A), the content of polymerized units based on the hydroxyl group-containing monomer is preferably 1 to 50 mol% with respect to all polymerized units.

  Monomer H other than the above may be copolymerized with the hydroxyl group-containing fluororesin (A). Examples of the monomer D include, for example, alkyl vinyl ethers having a cycloalkyl group or a branched alkyl group, alkyl vinyl ethers having a linear alkyl group, vinyl ethers such as glycidyl vinyl ether, and vinyl silanes such as vinyl trimethoxy silane and vinyl triethoxy silane. And vinyl esters of organic acids such as vinyl acetate, vinyl propionate and vinyl butyrate, alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether and butyl allyl ether, and olefins such as ethylene, propylene and butylene. These monomers may be used alone or in combination of two or more.

  Examples of the alkyl vinyl ether having a cycloalkyl group or a branched alkyl group include cyclohexyl vinyl ether, cyclopentyl vinyl ether, 2-ethylhexyl vinyl ether, tert-butyl vinyl ether, isobutyl vinyl ether, and 3-methylbutyl vinyl ether.

  Examples of the alkyl vinyl ether having a linear alkyl group include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, and pentyl vinyl ether.

  Hydroxyl group-containing fluororesin (A) can be obtained from commercial products, and copolymers of fluoroolefins such as “Lumiflon” (trade name, manufactured by Asahi Glass Co., Ltd.) and vinyl ethers have good paint stability and It is preferable at the point from which a weather resistance is acquired.

Polyester resin (B)
The polyester resin (B) having an acid value of 10 mgKOH / g or less and a hydroxyl value of 10 to 100 mgKOH / g (hereinafter sometimes abbreviated as “polyester resin (B)”) used in the powder coating composition of the present invention is: Usually, it can manufacture by esterification reaction or transesterification with a polybasic acid component and a polyhydric alcohol component. As said polybasic acid component, an alicyclic polybasic acid component, an aliphatic polybasic acid component, an aromatic polybasic acid component, etc. can be used, for example.

  As the alicyclic polybasic acid component, generally, a compound having one or more alicyclic structures (mainly 4 to 6-membered rings) and two or more carboxyl groups in one molecule, an acid anhydride of the compound And an esterified product of the compound. Examples of the alicyclic polybasic acid component include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3- Alicyclic polycarboxylic acids such as methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid An anhydride of these alicyclic polyvalent carboxylic acids; a lower alkyl esterified product of these alicyclic polyvalent carboxylic acids, and the like. An alicyclic polybasic acid component can be used individually or in combination of 2 or more types.

  As the alicyclic polybasic acid component, in particular, 1,2-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic anhydride, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene- 1,2-dicarboxylic acid and 4-cyclohexene-1,2-dicarboxylic anhydride can be preferably used. Among the above, 1,2-cyclohexanedicarboxylic acid and 1,2-cyclohexanedicarboxylic anhydride can be particularly preferably used from the viewpoint of hydrolysis resistance.

  The aliphatic polybasic acid component is generally an aliphatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aliphatic compound, and an esterified product of the aliphatic compound, for example, Aliphatic polycarboxylic acids such as acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, octadecanedioic acid, citric acid; An anhydride of a polyvalent carboxylic acid; a lower alkyl esterified product of these aliphatic polyvalent carboxylic acids. An aliphatic polybasic acid component can be used individually or in combination of 2 or more types.

  As the aliphatic polybasic acid component, it is preferable to use a dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms. Examples of the dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, and octadecanedioic acid. Among them, adipic acid can be preferably used.

  The aromatic polybasic acid component is generally an aromatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aromatic compound and a lower alkyl esterified product of the aromatic compound, For example, aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid; anhydrides of these aromatic polycarboxylic acids And lower alkyl esterified products of these aromatic polycarboxylic acids. An aromatic polybasic acid component can be used individually or in combination of 2 or more types.

  As the polyhydric alcohol component, a polyhydric alcohol having two or more hydroxyl groups in one molecule can be preferably used. Examples of the polyhydric alcohol include alicyclic diols, aliphatic diols, aromatic diols, and trihydric or higher polyhydric alcohols.

  The alicyclic diol is generally a compound having one or more alicyclic structures (mainly 4- to 6-membered rings) and two hydroxyl groups in one molecule. Examples of the alicyclic diol include dihydric alcohols such as 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol F; ε-caprolactone and the like in these dihydric alcohols. Examples include polylactone diol to which a lactone compound is added, and these can be used alone or in combination of two or more.

  The aliphatic diol is generally an aliphatic compound having two hydroxyl groups in one molecule. Examples of the aliphatic diol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3 -Butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3 -Pentanediol, 1,6-hexanediol, 1, -Hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol; polyethylene glycol, polypropylene glycol and poly Examples include polyether diol compounds such as butylene glycol, and these can be used alone or in combination of two or more.

  The aromatic diol is generally an aromatic compound having two hydroxyl groups in one molecule. Examples of the aromatic diol include ester diol compounds such as bis (hydroxyethyl) terephthalate; alkylene oxide adducts of bisphenol A and the like, and these can be used alone or in combination of two or more.

  Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, and mannitol. A trilactone or higher alcohol; a polylactone polyol compound obtained by adding a lactone compound such as ε-caprolactone to the trihydric or higher alcohol; tris (2-hydroxyethyl) isocyanurate, tris (2-hydroxypropyl) isocyanurate, And tris (hydroxyalkyl) isocyanurate such as tris (2-hydroxybutyl) isocyanurate. Of these, trimethylolpropane is particularly preferable.

  The production of the polyester resin (B) used in the present invention is not particularly limited, and can be performed according to a usual method. For example, it is produced by reacting an acid component having the polybasic acid component as an essential component and a polyhydric alcohol component at 150 to 250 ° C. for 5 to 10 hours in a nitrogen stream and performing an esterification reaction or a transesterification reaction. can do.

  In the esterification reaction or transesterification reaction, the acid component and alcohol component may be added at once, or may be added in several portions. Moreover, after synthesize | combining a carboxyl group-containing polyester resin first, you may esterify some carboxyl groups in this carboxyl group-containing polyester resin using the said alcohol component. Furthermore, after first synthesizing a hydroxyl group-containing polyester resin, the acid anhydride may be reacted to half-esterify the hydroxyl group-containing polyester resin.

  In the esterification or transesterification reaction, a catalyst may be used to promote the reaction. As the catalyst, known catalysts such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, and tetraisopropyl titanate can be used.

  Further, the polyester resin (B) can be modified with a fatty acid, an oil, a fat, a monoepoxy compound, a monoalcohol compound, a polyisocyanate compound or the like during the preparation of the resin, or after the esterification reaction or the transesterification reaction.

  Examples of the fatty acid include coconut oil fatty acid, cottonseed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, dehydrated castor Examples include fatty acids such as oil fatty acids and safflower oil fatty acids; lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and the like.

  Examples of the fat include coconut oil, cottonseed oil, hemp seed oil, rice bran oil, fish oil, tall oil, soybean oil, linseed oil, tung oil, rapeseed oil, castor oil, dehydrated castor oil, safflower oil and the like.

  Examples of the polyisocyanate compound used for the modification include aliphatic diisocyanate compounds such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane. -Aliphatic diisocyanate compounds such as 2,6-diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,3- (isocyanatomethyl) cyclohexane; aromatics such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate Diisocyanate compounds; organic polymers such as lysine triisocyanate Isocyanate itself, or an adduct of each of these organic polyisocyanates with polyhydric alcohol, low molecular weight polyester resin or water, or a cyclized polymer of each of the above organic diisocyanates (for example, isocyanurate), biuret type addition And the like. These can be used alone or in combination of two or more.

  The number average molecular weight of the polyester resin (B) is preferably 2,000 to 30,000, particularly within the range of 3,000 to 25,000, from the viewpoints of coating film hardness, workability, and finish of the resulting coating film. Is preferred.

The acid value of the polyester resin (B) is 10 mgKOH / g or less, preferably 1 to 6 mgKOH / g, from the viewpoint of finish. The hydroxyl value is in the range of 10 to 100 mgKOH / g, preferably 20 to 70 mgKOH / g, from the viewpoint of coating film hardness and adhesion. Here, the acid value is obtained by determining the number of mg of potassium hydroxide necessary for neutralizing the acidic free functional group contained in 1 g of the resin by a conventional method based on alkali neutralization titration. Moreover, the measurement of a hydroxyl value can be performed based on JISK-0070 (1992). Specifically, 5 ml of acetylating reagent (acetic anhydride pyridine solution adjusted to 100 ml by adding pyridine to 25 g of acetic anhydride) was added to the sample, heated in a glycerin bath, and then added with potassium hydroxide solution. It can be titrated with phenolphthalein as an indicator and calculated by the following formula.
Hydroxyl value (mgKOH / g) = [V × 56.1 × C / m] + D
V: titer (ml),
C: concentration of titrant (mol / l),
m: solid content mass (g) of the sample,
D: Acid value of the sample (mgKOH / g).

Blocked polyisocyanate (C)
The blocked polyisocyanate (C) in the powder coating composition of the present invention is a fragrance such as a compound having two or more isocyanate groups in one molecule, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, etc. Aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, lysine diisocyanate; alicyclic diisocyanates such as methylene bis (cyclohexyl isocyanate), isophorone diisocyanate, methylcyclohexane diisocyanate, cyclohexane diisocyanate and cyclopentane diisocyanate; Biuret type adduct of polyisocyanate Allophanate type adducts, isocyanurate ring type adducts; isocyanates obtained by reacting these polyisocyanates with low molecular weight or high molecular weight polyol compounds (for example, acrylic polyols, polyester polyols, polyether polyols, etc.) in excess of isocyanate groups. Examples thereof include blocked polyisocyanate compounds in which free isocyanate groups are blocked with a polyisocyanate such as a group-containing prepolymer by a blocking agent.

  Examples of the blocking agent include phenolic compounds, oxime compounds, active methylene compounds, lactam compounds, alcohol compounds, mercaptan compounds, acid amide compounds, imide compounds, amine compounds, imidazole compounds, urea compounds, and carbamic acid. Compound, imine compound and the like.

  In addition, the powder coating composition of this invention is a component with respect to a solid content total of 100 mass parts of binder components containing a hydroxyl-containing fluororesin (A), a polyester resin (B), and blocked polyisocyanate (C). (A) 20-55 parts by mass, preferably 30-45 parts by mass, component (B) 20-55 parts by mass, preferably 30-45 parts by mass, and component (C) 10-40 parts by mass, preferably 15- 30 parts by mass is preferable from the viewpoints of coating film hardness and adhesion.

Acrylic fine particles (D)
The powder coating composition of the present invention is excellent in finish, coating film hardness, weather resistance and adhesion by containing acrylic fine particles (D) having a volume average particle diameter of 21 to 45 μm as a matting agent. In addition, a matte coating film can be obtained.

  The method for producing the acrylic fine particles (D) is not particularly limited, and is polymerizable unsaturated by a polymerization method known per se, for example, suspension polymerization, solution polymerization, emulsion polymerization, bulk polymerization and the like. It can be obtained by reacting monomers. Among these polymerization methods, suspension polymerization is particularly preferable.

  Examples of the polymerizable unsaturated monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth) acrylate. , Tert-butyl (meth) acrylate, 2-ethylhexyl acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, octadecyl (meth) acrylate, isostearyl (meth) acrylate, etc. 1-24 alkyl (meth) acrylates; styrene, vinyl acetate; acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile; carboxylic acids such as maleic acid, maleic anhydride, crotonic acid, itaconic acid Group containing monomers; nitrogen-containing alkyl (meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, Nt-butylaminoethyl (meth) acrylate; acrylamide , Methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N, N- Polymerizable amides such as dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide; 2-vinylpyridine, 1-vinyl-2-pyrrolidone, 4 -Vinylpyridine, a Nitrogen-containing monomers such as ruamine; 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2,3-dihydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and polyethylene glycol mono (meth) acrylate Mono-esterified product of polyhydric alcohol such as acrylic acid or methacrylic acid; hydroxyl group-containing monomer such as a compound obtained by ring-opening polymerization of ε-caprolactone to the monoesterified product of polyhydric alcohol and acrylic acid or methacrylic acid; 1 molecule Examples thereof include monomers having two or more polymerizable unsaturated groups.

  These polymerizable unsaturated monomers can be used alone or in combination of two or more.

  In the present specification, “(meth) acrylate” means acrylate or methacrylate, “(meth) acrylic acid” means acrylic acid or methacrylic acid, and “(meth) acrylamide” means acrylamide or methacrylic acid. Means amide.

  The acrylic fine particles (D) used in the powder coating composition of the present invention are desirably acrylic fine particles containing a copolymer of a monomer mixture containing methyl (meth) acrylate for improving weather resistance. The acrylic fine particles (D) may be crosslinked.

  The acrylic fine particles (D) have a volume average particle diameter of 21 to 45 μm, more preferably 25 to 40 μm, and a matte coating film with excellent finish of 60 ° specular gloss of 50 or less, preferably 30 or less. Suitable for obtaining. In addition, the volume average particle diameter of the acrylic fine particles (D) in the present specification was measured using Microtrac MT3300 (Microtrac Bell, wet particle size distribution measuring device).

  As a commercial item of the said acrylic type microparticles | fine-particles (D), specifically, Ganzpearl GB-22S (Aika Industry Co., Ltd. make, a brand name, a volume average particle diameter of 22 micrometers, an acrylic resin particle), Techpolymer SSX-127 ( Product name, volume average particle size 27 μm, polymethyl methacrylate resin particles), Techpolymer MBX-30 (product name, volume average particle size 30 μm, polymethacrylic product, manufactured by Sekisui Plastics Industry Co., Ltd.) Acid methyl resin particles), Techpolymer MBX-40 (manufactured by Sekisui Plastics Industry Co., Ltd., trade name, volume average particle diameter 40 μm, polymethyl methacrylate resin particles), Techpolymer MB20X-30 (manufactured by Sekisui Plastics Industry Co., Ltd.) , Trade name, volume average particle diameter 30 μm, polymethyl methacrylate resin particles), Tufic AR-650M (Toyobo Co., Ltd.) Product name, volume average particle diameter 30 μm, polymethyl methacrylate resin particles), Tufic AR-650MX (trade name, volume average particle diameter 40 μm, polymethyl methacrylate resin particles) manufactured by Toyobo Co., Ltd. Can be mentioned.

  The blending ratio of the acrylic fine particles (D) is acrylic with respect to a total solid content of 100 parts by mass of the binder component including the hydroxyl group-containing fluororesin (A), the polyester resin (B) and the blocked polyisocyanate (C). A matte coating film excellent in finish, coating film hardness, weather resistance, and adhesion to a substrate is obtained in the range of 1 to 40 parts by mass, and further 5 to 25 parts by mass of the system fine particles (D). Therefore, it is suitable.

  Further, when the blending amount of the acrylic fine particles (D) is less than 1 part by mass, a matte coating film may not be obtained, and when the blending amount of the acrylic fine particles (D) exceeds 20 parts by mass, the finished product is obtained. And weatherability may be impaired.

Color pigment (E)
Examples of the color pigment (E) include titanium dioxide, carbon black, quinacridone, diketopyrrolopyrrole, isoindolinone, indanthrone, perylene, perinone, anthraquinone, dioxazine, benzimidazolone, triphenylmethanequinophthalone, anthra Pyrimidine, yellow lead, pearl mica, transparent pearl mica, colored mica, interference mica, phthalocyanine, halogenated phthalocyanine, azo pigment (azomethine metal complex, condensed azo, etc.), iron oxide, copper phthalocyanine, condensed polycyclic pigment, etc. be able to.

  Specific examples of the commercially available titanium dioxide pigment (e) include Ti-Pure R960 (manufactured by DuPont, trade name), Type CR-95 (trade name, manufactured by Ishihara Sangyo Co., Ltd.), and the like.

  In addition, the compounding quantity of a coloring pigment (E) is a coloring pigment (A solid content of a binder component containing a hydroxyl-containing fluororesin (A), a polyester resin (B), and blocked polyisocyanate (C) total 100 mass parts). E) is preferably contained in an amount of 0.5 to 100 parts by mass, preferably 1 to 60 parts by mass, from the viewpoint of finish and weather resistance.

Extender Pigment The powder coating composition of the present invention may contain a known extender pigment as necessary. Examples of the extender pigment include barium sulfate, calcium carbonate, hydrous magnesium silicate (talc), magnesium carbonate, calcium sulfate (gypsum), diatomaceous earth, mica (mica powder), nepheline sinite, silica, Neuburg silica clay, and the like. It is done. As a commercial item of the above-mentioned nepheline cynite, Minex EX (made by Shiraishi Calcium Co., Ltd., trade name) and the like can be mentioned. From the viewpoint of coating film hardness, barium sulfate is particularly preferable as the extender pigment. The volume average particle diameter of the barium sulfate is preferably 0.1 μm or more, more preferably 0.3 μm or more, and further preferably 0.5 μm or more. Further, the volume average particle diameter of the barium sulfate is preferably 20 μm or less, more preferably 10.0 μm or less, and further preferably 3.0 μm or less. For example, the volume average particle diameter of the barium sulfate is in the range of 0.1 to 20 μm, preferably in the range of 0.1 to 10.0 μm, more preferably 0.3 to 10.0 μm (preferably 0.5 to 10.0 μm), more preferably 0.3 to 3.0 μm (preferably 0.5 to 3.0 μm). The use of barium sulfate having a volume average particle diameter in the above range is particularly preferred from the viewpoints of coating film hardness and coating finish.

  Specifically as a commercial item of the said barium sulfate, TS-1 (Takehara chemical industry make, brand name, volume average particle diameter 0.6 micrometer), TS-2 (Takehara chemical industry make, brand name, volume) Average particle diameter 0.3 μm), P-30 (Takehara Chemical Industries, trade name, volume average particle diameter 1.0 μm), W-1 (Takehara Chemical Industries, trade name, volume average particle diameter 1.5 μm) ), W-6 (Takehara Chemical Industries, trade name, volume average particle diameter 4.5 μm), W-10 (Takehara Chemical Industries, trade name, volume average particle diameter 10.0 μm), AC-200 ( Takehara Chemical Industries, trade name, volume average particle diameter 15.0 μm) and the like. The volume average particle diameter was measured using Microtrac MT3300 (Microtrac Bell, wet particle size distribution measuring device).

  In addition, when mix | blending barium sulfate, the compounding quantity is sulfuric acid with respect to 100 mass parts of solid content total of a binder component containing a hydroxyl-containing fluororesin (A), a polyester resin (B), and blocked polyisocyanate (C). It is desirable to contain 1 to 50 parts by mass, preferably 2 to 30 parts by mass of barium, from the viewpoint of improving the finish of the matte coating obtained.

Other components The powder coating composition of the present invention includes, as necessary, a rust preventive pigment, a surface conditioner, a fluidity conditioner, an acrylic resin, a phenol resin, an epoxy resin, a silicone resin, and a curing catalyst. Antifoaming agent, pigment dispersant, UV absorber, light stabilizer, antioxidant, magnetic powder, leveling agent, anti-waxing agent such as benzoin, plasticizer, charge control agent, silane coupling agent, etc. Can do.

  Examples of the rust preventive pigment include zinc oxide, phosphite compounds, phosphate compounds, molybdate compounds, bismuth compounds, and metal ion exchange silica.

  Examples of the curing catalyst include metal compounds such as tin and bismuth, organic acid compounds, and organic base compounds.

  Examples of the epoxy resin include bisphenol A type diglycidyl ether resin, bisphenol F type diglycidyl ether resin, aminoglycidyl ether resin, bisphenol AD type diglycidyl ether resin, and novolac type epoxy resin. Examples of the novolac type epoxy resin include a phenol novolac type epoxy resin and a cresol novolac type epoxy resin. From the viewpoint of the weather resistance of the resulting coating film, the content of the epoxy resin is preferably less than 1 part by mass with respect to 100 parts by mass of the powder coating composition of the present invention. In the composition of this invention, even when it does not contain an epoxy resin, the coating film which has sufficient adhesiveness with respect to a base material can be obtained.

  Commercially available products of the surface conditioner include Acronal 4F (trade name, manufactured by BASF), Polyflow S (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), Regiflow LV, Regiflow P67 (above, product name, manufactured by ESTRON CHEMICAL), Modaflow. III (manufactured by Monsanto, trade name) or the like is preferably used.

  As the fluidity adjusting agent, hydrophobic silica, hydrophilic silica, aluminum oxide, or the like can be applied.

  It does not specifically limit as a manufacturing method of the powder coating composition of this invention, A well-known method is employable. For example, a hydroxyl group-containing fluororesin (A), a polyester resin (B), a blocked polyisocyanate (C), an acrylic fine particle (D), a color pigment (E), and an extender pigment and other components as necessary. It can be produced by dry blending with a mixer, blender or the like, followed by heat-melt kneading, cooling, coarse pulverization, fine pulverization, and filtration.

  Further, for example, a hydroxyl group-containing fluororesin (A), a polyester resin (B), a blocked polyisocyanate (C), a color pigment (E), and, if necessary, an extender pigment and other components, a mixer, a blender, etc. After dry blending, the mixture may be heated, melted and kneaded, and after cooling, the acrylic fine particles (D) may be dry blended, coarsely pulverized, finely pulverized, and filtered.

About the coating-film formation method The powder coating composition of this invention can be coated on the conventionally used base material. Examples of the base material include zinc, iron, aluminum, magnesium, steel and alloys thereof, metal base materials such as galvanized steel sheets, those having a chemical conversion coating formed on the metal surface, and these metal surfaces. Examples include anodized ones, and coated metal substrates obtained by applying primer coating or electrodeposition coating to these metal substrates as necessary. Examples of the chemical conversion treatment liquid used for forming the chemical conversion treatment film include a phosphate treatment liquid, a zirconium treatment liquid, a chromate treatment liquid, and the like.

  The powder coating composition of the present invention can be applied by an electrostatic powder coating method, specifically, a corona charging method, a friction charging method, etc., and a dry film thickness of 20 to 150 μm, preferably a dry film. It can be applied in the range of 30 to 80 μm in thickness. Baking of the powder coating composition of the present invention can be performed at 150 to 250 ° C. for 10 to 60 minutes, preferably at 170 to 230 ° C. for 10 to 30 minutes. By coating and baking the powder coating composition of the present invention, a coating film formed by curing the powder coating composition can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited thereto. In each example, “parts” indicates mass parts, and “%” indicates mass%.

(Production Example 1) Acrylic fine particles No. Example 1
Through the following steps 1 to 2, acrylic fine particles No. 1 was obtained.

Step 1: Synthesis of polyacrylonitrile resin before pulverization
An aqueous solution in which 10 parts of polyvinyl alcohol (Kuraray PVA217), 10 parts of sodium sulfate and 1 part of copper sulfate pentahydrate are dissolved in 778 parts of deionized water is charged into a glass reaction vessel. Next, 160 parts of acrylonitrile, 40 parts of methyl methacrylate, and 2 parts of 2,2′-azobis (2-methylvaleronitrile) as a catalyst were added to the reaction vessel as a monomer and stirred. The liquid temperature was raised to 50 ° C. and the temperature was maintained for 5 hours to obtain an aqueous dispersion of polyacrylonitrile resin. Thereafter, the polyacrylonitrile-based resin aqueous dispersion was subjected to solid-liquid separation and dried with a hot air dryer at 70 ° C. to obtain a polyacrylonitrile-based resin.

Step 2: Manufacture of acrylic fine particles of resin by pulverization The polyacrylonitrile resin obtained in Step 1 is pulverized with a vertical mill (SH-75 type, manufactured by Ishikawajima-Harima Heavy Industries Co., Ltd.), and acrylic fine particles No. . 1 was obtained.

(Production Example 2) Acrylic fine particles No. Production Example 2 According to the following steps 1 to 2, acrylic fine particles No. 2 was obtained.

Step 1: Synthesis of polymethyl methacrylate resin before pulverization
An aqueous solution in which 7 parts of polyvinyl alcohol (Kuraray, PVA217), 10 parts of sodium sulfate, and 1 part of copper sulfate pentahydrate are dissolved in 831 parts of deionized water is charged into a glass reaction vessel. Next, 135 parts of methyl methacrylate, 15 parts of ethylene glycol dimethacrylate, and 1 part of 2,2′-azobis (2-methylvaleronitrile) as a catalyst were added to the reactor as monomers, and stirred. While increasing the liquid temperature to 50 ° C. and maintaining the temperature for 5 hours, an aqueous dispersion of a polymethyl methacrylate resin was obtained. Thereafter, the polymethyl methacrylate resin was dried with a hot air dryer at 70 ° C. to obtain a polymethyl methacrylate resin.

Process 2: Production of acrylic fine particles of resin by pulverization
The polymethyl methacrylate resin obtained in Step 1 was pulverized with a vertical mill (SH-75 type, manufactured by Ishikawajima-Harima Heavy Industries Co., Ltd.). 2 was obtained.

Examples and Comparative Examples
Example 1 Powder coating composition No. 1 Lumiflon 710 (Note 1) 41 parts (solid content), Iupika Coat GV-560 (Note 2) 41 parts (solid content), Vestagon B1530 (Note 5) 18 parts (solid content), Tufic AR-650M (Note 9) 10 parts (solid content), Ti-Pure R960 (Note 16) 35 parts, Polyflow S (Note 25) 0.8 part and benzoin 0.6 part, high speed mixer (Fukae Industrial Co., Ltd., (Product name, capacity 2 liters), and stirred for 1 minute under the conditions of agitator 500 rpm and chopper 4000 rpm to mix uniformly.

  Next, the mixture was melt-kneaded at 120 ° C. using an extrusion kneader (Busconyder PR46, manufactured by Buss AG, trade name), and discharged into a metal vat. After cooling to 50 ° C. or lower, finely pulverized with a hammer-type impact pulverizer and classified with a 150 mesh wire mesh, a powder coating composition No. 4 having an average particle diameter of 40 μm was obtained. 1 was created.

(Examples 2 to 22) Powder coating composition No. 2-No. The powder coating composition No. 1 was prepared in the same manner as in Example 1 except that the contents of preparation in Production Table 1 and Table 2 in Table 22 were used. 2-No. 22 was created.

Comparative Examples 1-14 Powder coating composition No. 23-No. Production of powder coating composition No. 36 was carried out in the same manner as in Example 1, except that the contents of Table 3 were used. 23-No. 36 was created.

(Note 1) Lumiflon 710F: manufactured by Asahi Glass Co., Ltd., trade name, hydroxyl group-containing fluororesin that is a copolymer of fluoroolefins and vinyl ethers, hydroxyl value 46 mgKOH / g
(Note 2) Iupika Coat GV-560: manufactured by Nippon Iupika Co., Ltd., trade name, polyester resin, acid value 5 mgKOH / g, hydroxyl value 50 mgKOH / g
(Note 3) Finedec A-239-X: manufactured by DIC, trade name, polyester resin, acid value 14 mgKOH / g, hydroxyl value 22 mgKOH / g
(Note 4) Polyester resin A: Made in-house, acid value 20 mgKOH / g, hydroxyl value 50 mgKOH / g
(Note 5) Vestagon B1530: Degussa, trade name, isophorone diisocyanate blocked with ε-caprolactam (Note 6) JER 1001: bisphenol A type epoxy equivalent 450-500, softening point 64 ° C., Mitsubishi Chemical
JER 1004: Mitsubishi Chemical Bisphenol A type epoxy equivalent 875-975, softening point 97 ° C
(Note 7) Gantz Pearl GB-22S: Aika Kogyo Co., Ltd., trade name, volume average particle diameter 22 μm, acrylic cross-linked resin particles (Note 8) Techpolymer SSX-127: Sekisui Plastics Co., Ltd., trade name , Volume average particle diameter 27 μm, polymethyl methacrylate-based crosslinked resin particles (Note 9) Techpolymer MBX-30: manufactured by Sekisui Plastics Co., Ltd., trade name, volume average particle diameter 30 μm, polymethyl methacrylate-based crosslinked resin particles (Note 10) Techpolymer MBX-40: manufactured by Sekisui Plastics Co., Ltd., trade name, volume average particle diameter of 40 μm, polymethyl methacrylate-based crosslinked resin particles (Note 11) Tufic AM: manufactured by Toyobo Co., Ltd., trade name , Volume average particle diameter 10 μm, polyacrylonitrile resin particles (Note 12) Gantz Pearl GM10K: Aika Kogyo Co., Ltd., trade name, volume flat Particle size 10 μm, polypolymethyl methacrylate resin particles (Note 13) Tufic AR650ML: manufactured by Toyobo Co., Ltd., trade name, average particle size 80 μm, polymethyl methacrylate resin particles (Note 14) Tuftic AR650L: manufactured by Toyobo Co., Ltd. Product name, average particle size 100 μm, polymethyl methacrylate resin particles (Note 15) Tuftic FH-S005: manufactured by Toyobo Co., Ltd., product name, volume average particle size 5 μm
(Note 16) Ti-PureR960: DuPont Co., Ltd., trade name, Titanium white (Note 17) Typaque CR-97: Ishihara Sangyo Co., Ltd., trade name, Titanium white (Note 18) Varifine BF-20: Made by Sakai Chemical Industry Co., Ltd., trade name, barium sulfate, average particle size 0.03μm
(Note 19) Precipitated barium sulfate TS-1: manufactured by Takehara Chemical Co., Ltd., trade name, volume average particle diameter 0.6 μm
(Note 20) Polyflow S: Kyoeisha Chemical Co., Ltd., trade name, surface conditioner

Preparation of test plate A zirconium-based chemical conversion treatment liquid was applied to a cold-rolled steel plate (70 mm x 150 mm x 0.8 mm) to form a chemical conversion film. Next, each powder coating composition is electrostatically powdered on the chemical conversion coating so that the dry film thickness is 40 μm using an electrostatic coating machine PG-1 (trade name, manufactured by Asahi Sunac Co., Ltd.). Painted. Subsequently, each test plate was obtained by heating and drying under the condition that the surface temperature of the article to be coated was 200 ° C. and the holding time was 20 minutes.

Coating Film Performance Test Using the above test plate, the coating film performance test was performed according to the test conditions described below. A result is combined with Tables 1-3 and shown.

(Note 21) Finishability:
The finish of the coating was evaluated according to the following criteria:
◎ indicates good skin condition without any skin, glossy, repellency, butteriness, or dents. ○ indicates that any of skinnyness, glossy, repellency, buttery, or dents is observed, but there are no practical problems. .

Δ indicates any of yuzu skin, glossy, repellent, buttery, and dents. × indicates that any of yuzu skin, glossy, repelling, buttery, and dents is significant.

(Note 22) Coating film hardness (pencil hardness):
About the coating film hardness of a test board, the pencil scratch test prescribed | regulated to JISK5600-5-4 (1999) was done, and the evaluation by the tear of a coating film was performed:
◎: Pencil hardness to tear the coating film is 2H ○: Pencil hardness to tear the coating film is H △: Pencil hardness to tear the coating film is F ×: Pencil hardness to tear the coating film is B It is as follows.

(Note 23) Weather resistance:
Time when exposure test is performed using a sunshine weatherometer (according to JIS K 5600-7-7) using a carbon arc lamp type accelerated weathering tester, and the gloss retention with respect to the coating film gloss before the exposure test is 80% Was used to evaluate the weather resistance of the coating:
◎: Time when gloss retention is less than 80% is 5,000 hours or more ○: Time when gloss retention is less than 80% is 3,500 hours or more and less than 5,000 hours △: Gloss retention is Less than 80% time 2,000 hours or more and less than 3,500 hours,
X is less than 2,000 hours when the gloss retention is below 80%.

(Note 24) Adhesion:
The test plate was used and immersed in warm water at 40 ° C. according to JIS K 5600-6-2 (1999) and pulled up after 240 hours. Next, in accordance with JIS K 5600-5-6 (1999) grid pattern-tape method, a knife is used to reach the substrate on the paint film surface of the coated plate in parallel with each other at intervals of about 2 mm. A slit of a book was formed to form a goblet, a cellophane (registered trademark) adhesive tape was applied to the surface, and the gobain coated surface after the tape was abruptly peeled was evaluated according to the following criteria:
◎: no peeling of the coating film is observed ○: slight peeling is observed in a part of the coating film at the corner of the knife scratch The number of 20 × means that 21 or more of the 100 gobangs are peeled off.

(Note 25) 60 degree specular gloss:
The degree of gloss of the test plate was measured according to JIS K 5600-4-7 (1999) 60 degree specular gloss, and the reflectivity was measured when the incident angle was 60 degrees. Is expressed as a percentage with respect to 100:
◎: 60 degree specular gloss is 1 or more and 30 or less ○: 60 degree specular gloss is over 30 and 50 or less
Δ is 60 degree specular gloss greater than 50 and less than 70
X: 60 degree specular gloss exceeds 70.

  In the technical field to which the present invention belongs, it is preferable to obtain a matte coating film excellent in finish, coating film hardness, weather resistance, adhesion and glossiness. Therefore, it is preferable that the finish, coating film hardness, weather resistance, adhesion and gloss are all evaluated as ◎ or ◯.

  A coated plate having excellent finish, coating film hardness, weather resistance and adhesion, and having a matte coating film can be provided.

Hereinafter, although a production example , a reference example , an example, and a comparative example explain the present invention still in detail, the present invention is not limited to this. In each example, “parts” indicates mass parts, and “%” indicates mass%.

Reference examples, examples and comparative examples
Reference Example 1 Powder coating composition No. 1 Lumiflon 710 (Note 1) 41 parts (solid content), Iupika Coat GV-560 (Note 2) 41 parts (solid content), Vestagon B1530 (Note 5) 18 parts (solid content), Tufic AR-650M (Note 9) 10 parts (solid content), Ti-Pure R960 (Note 16) 35 parts, Polyflow S (Note 25) 0.8 part and benzoin 0.6 part, high speed mixer (Fukae Industrial Co., Ltd., (Product name, capacity 2 liters), and stirred for 1 minute under the conditions of agitator 500 rpm and chopper 4000 rpm to mix uniformly.

(Reference Example 2, Examples 1 to 20) Powder coating composition No. 2-No. The powder coating composition No. 1 was prepared in the same manner as in Reference Example 1, except that the contents of preparation in Production Table 1 and Table 2 in Table 22 were used. 2-No. 22 was created.

Comparative Examples 1-14 Powder coating composition No. 23-No. Production of Powder Coating Composition No. 36 was carried out in the same manner as in Reference Example 1, except that the contents of Table 3 were used. 23-No. 36 was created.

Claims (4)

A binder component containing a hydroxyl group-containing fluororesin (A), a polyester resin (B) having an acid value of 10 mgKOH / g or less and a hydroxyl value of 10 to 100 mgKOH / g, and a blocked polyisocyanate (C), having a volume average particle size of 21 to 45 μm A powder coating composition containing acrylic fine particles (D) and a color pigment (E), wherein 20 to 55 parts by mass of component (A) is added to 100 parts by mass of the solid content of the binder component. 20 to 55 parts by mass of (B), 10 to 40 parts by mass of component (C), 1 to 40 parts by mass of acrylic fine particles (D), and 0.5 to 100 parts by mass of color pigment (E). A powder coating composition characterized by the above. The powder coating composition according to claim 1, wherein the volume average particle diameter of the acrylic fine particles (D) is 25 to 40 µm. Barium sulfate having a volume average particle size of 0.1 to 20 μm is added to 100 parts by mass of the solid content of the binder component including the hydroxyl group-containing fluororesin (A), the polyester resin (B) and the blocked polyisocyanate (C). The powder coating composition according to claim 1 or 2, comprising 1 to 50 parts by mass. The coated article which has a coating film whose 60 degree specular glossiness is 50 or less consisting of the hardened | cured material of the powder coating composition of any one of Claims 1-3.