JP6948371B2 - Matte powder coating composition and coated products - Google Patents

Description

The present invention relates to a matte powder coating composition and a coated product. More specifically, the present invention relates to a matte powder coating composition and a coated product for obtaining a coating film having excellent smoothness, arbitrary gloss adjustment, and excellent scratch resistance. ..

Conventionally, powder paints have been attracting attention as low-pollution paints because organic solvents do not volatilize into the atmosphere during painting, and switching from solvent paints is progressing. Under such circumstances, the blocked isocyanate-curable polyester powder coating material has a problem that the coating film turns yellow during heat curing due to the blocking agent ε-caprolactam. On the other hand, HAA (β-hydroxyalkylamide) -based cured polyester powder coating material that does not contain a blocking agent "does not generate ε-caprolactam gas, which is one of the causes of yellowing" and "cures" during heat curing. It is attracting attention because it can lower the temperature.

By the way, powder coating materials are used in many fields such as home appliances, automobiles, and building materials. From an aesthetic point of view, the coating film is glossy (about 90 to 100% with a 60-degree mirror gloss), semi-matte (about 30 to 70% with a 60-degree mirror gloss), and matte (about 30 with a 60-degree mirror gloss). % Or less) may be required. Among them, indoor products are required to have a calm appearance, and therefore, there is a great demand for glossiness of 60% or less (particularly 45% or less). Therefore, techniques for obtaining various matting effects have been proposed (Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 2009-215372 Japanese Unexamined Patent Publication No. 10-7944 Japanese Patent No. 48976787 Japanese Unexamined Patent Publication No. 2000-119561

However, the matte powder coating composition described in Patent Document 1 is inferior in convenience because a plurality of powder coating compositions must be used in order to adjust the gloss value. Further, the matte powder coating material described in Patent Document 1 tends to have low uniformity when a plurality of powder coating compositions are mixed. Further, since the resin composition described in Patent Document 2 contains a high acid value resin, it gels quickly and the smoothness of the coating film tends to be inferior. Further, the matte coating film using the extender pigment described in Patent Document 3 is inferior in physical properties and smoothness of the obtained coating film when a large amount of a pigment such as titanium oxide is blended in order to impart sufficient matteness. Cheap. Further, the powder coating composition described in Patent Document 4 has insufficient scratch resistance of the obtained coating film, and has a problem that it is easily scratched when the base materials are rubbed against each other or with nails during transportation or use. there were.

The present invention has been made in view of such conventional problems, and is used to obtain a coating film having excellent smoothness, arbitrary gloss adjustment, and excellent scratch resistance. It is an object of the present invention to provide an erasable powder coating composition and a coated product.

As a result of diligent studies to solve the above problems, the present inventor can appropriately solve the above problems by using a polyester resin, a curing agent, and a plurality of polyolefin waxes having a specific melting point in combination. We found that and completed the present invention. That is, the matte powder coating composition and the coated product of the present invention that solve the above problems mainly include the following configurations.

(1) A curable resin, a curing agent, and a polyolefin wax are contained, and the polyolefin wax contains a polyolefin wax A having a melting point of 141 to 180 ° C. and a polyolefin wax B having a melting point of 90 to 140 ° C. , Matte powder coating composition.

According to such a configuration, the obtained coating composition can form a coating film having excellent smoothness, optionally adjusting gloss, and excellent scratch resistance.

(2) The matte powder coating composition according to (1), wherein the curable resin contains a polyester resin.

According to such a configuration, the obtained coating film has more excellent coating film physical characteristics such as weather resistance.

(3) The matte powder coating composition according to (2), wherein the polyester resin contains a carboxyl group-containing polyester resin.

According to such a configuration, the obtained coating film exhibits excellent smoothness and physical characteristics of the coating film.

(4) The matte powder coating composition according to any one of (1) to (3), wherein the blending ratio (mass ratio) of the polyester resin and the polyolefin wax is 100: 6 to 100:20. thing.

According to such a configuration, the obtained coating composition can easily form a coating film having a glossiness of 45% or less.

(5) The matte according to any one of (1) to (4), wherein the blending ratio (mass ratio) of the polyolefin wax A and the polyolefin wax B is 10: 0.3 to 10:30. Powder coating composition.

According to such a configuration, the obtained coating film has excellent scratch resistance.

(6) The matte powder coating composition according to any one of (1) to (5), wherein the curing agent contains at least one of β-hydroxyalkylamide, a glycidyl group-containing acrylic resin and an epoxy resin. ..

According to such a configuration, the coating composition is preferable from the viewpoint of curability at low temperature and a deblocking agent.

(7) A coated product containing a base material and a coating film layer formed on the base material by the matte powder coating composition according to any one of (1) to (6).

According to such a configuration, the obtained coated product has excellent smoothness, easy to adjust gloss arbitrarily, and excellent scratch resistance.

According to the present invention, there is provided a matte powder coating composition and a coated product for obtaining a coating film having excellent smoothness, arbitrary gloss adjustment, and excellent scratch resistance. Can be done.

<Matte powder coating composition>
The matte powder coating composition of one embodiment of the present invention (hereinafter, also referred to as a coating composition) contains a curable resin, a curing agent, and a polyolefin wax. The polyolefin wax includes a polyolefin wax A having a melting point of 141 to 180 ° C. and a polyolefin wax B having a melting point of 90 to 140 ° C. Each will be described below.

(Curable resin)
The curable resin is not particularly limited as long as it is used for ordinary powder coating materials. The curable resin is, for example, a polyester resin, an epoxy resin, an acrylic resin, a fluororesin, or the like. These curable resins may be used in combination. By using a curable resin in combination, a hybrid type powder coating material can be obtained. Among these, the curable resin preferably contains a polyester resin from the viewpoint of excellent coating film physical properties such as weather resistance.

-Polyester resin The polyester resin is not particularly limited. As an example, the polyester resin can be produced by an esterification reaction with a polybasic acid component and a polyhydric alcohol component, or a transesterification reaction. The polybasic acid component is, for example, an alicyclic polybasic acid component, an aliphatic polybasic acid component, an aromatic polybasic acid component, or the like.

The alicyclic polybasic acid component is generally a compound having one or more alicyclic structures (mainly 4- to 6-membered rings) and two or more carboxyl groups in one molecule, and an acid anhydride of such a compound. And an esterified product. The alicyclic polybasic acid component is, for example, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3-methyl-. Alicyclic polyvalent carboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid; Anhydrous of alicyclic polyvalent carboxylic acids; lower alkyl esterified products of these alicyclic polyvalent carboxylic acids and the like. The alicyclic polybasic acid component may be used in combination.

The alicyclic polybasic acid component is 1,2-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid anhydride, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2. −Dicarboxylic acid and 4-cyclohexene-1,2-dicarboxylic acid anhydride are preferable, and 1,2-cyclohexanedicarboxylic acid and 1,2-cyclohexanedicarboxylic acid anhydride are used because of their excellent hydrolysis resistance. Is even more preferable.

The aliphatic polybasic acid component is, for example, 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. More specifically, the aliphatic polybasic acid components include succinic acid, glutaric acid, adipic acid, pimeric acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, octadecanedic acid, An aliphatic polyvalent carboxylic acid such as citric acid; an anhydride of these aliphatic polyvalent carboxylic acids; a lower alkyl esterified product of these aliphatic polyvalent carboxylic acids and the like. The aliphatic polybasic acid component may be used in combination.

The aliphatic polybasic acid component is preferably a dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms. The dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms is, for example, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanedioic acid, brassic acid, octadecanedioic acid and the like. It is preferably an acid.

The aromatic polybasic acid component is an aromatic compound having two or more carboxyl groups in one molecule, an acid anhydride of such an aromatic compound, a lower alkyl esterified product, and the like. More specifically, the aromatic polybasic acid component includes, for example, phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid and the like. Hyvalent carboxylic acids; anhydrides of these aromatic polyvalent carboxylic acids; lower alkyl esterified products of these aromatic polyvalent carboxylic acids and the like. The aromatic polybasic acid component may be used in combination.

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 preferably a compound having one or more alicyclic structures (mainly 4- to 6-membered rings) and two hydroxyl groups in one molecule. The alicyclic diol is, for example, a dihydric alcohol such as 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, hydrogenated bisphenol A, or hydrogenated bisphenol F; these dihydric alcohols are combined with a lactone compound such as ε-caprolactone. Examples thereof include polylactone diols to which the above is added. These may be used in combination with alicyclic diols.

The aliphatic diol is preferably an aliphatic compound having two hydroxyl groups in one molecule. The aliphatic diol includes, for example, ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, and 2,3-butane. Glycol, 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-Pentane Glycol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol , Neopentyl glycol; polyether diol compounds such as polyethylene glycol, polypropylene glycol and polybutylene glycol and the like can be mentioned. Aliphatic diols may be used in combination.

The aromatic diol is preferably an aromatic compound having two hydroxyl groups in one molecule. Examples of the aromatic diol include an ester diol compound such as bis (hydroxyethyl) terephthalate; and an alkylene oxide adduct of bisphenol A. Aromatic diols may be used in combination.

The trihydric or higher polyhydric alcohols include, for example, glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, mannit and the like. High-valent alcohols; Polylactone polyol compounds obtained by adding lactone compounds such as ε-caprolactone to these trivalent or higher-valent alcohols; Tris (2-hydroxyethyl) isocyanurate, Tris (2-hydroxypropyl) isocyanurate, Tris Examples thereof include tris (hydroxyalkyl) isocyanurate such as (2-hydroxybutyl) isocyanurate. The trihydric or higher polyhydric alcohol is preferably trimethylolpropane.

The method for producing the polyester resin is not particularly limited. As an example, in a polyester resin, for example, an acid component containing a polybasic acid component as an essential component and a polyhydric alcohol component are reacted in a nitrogen stream at 150 to 250 ° C. for 5 to 10 hours to carry out an esterification reaction. It can be produced by carrying out a transesterification reaction.

In the esterification reaction or transesterification reaction, the acid component and the alcohol component may be added at once, or may be added in several portions. Further, first, a carboxyl group-containing polyester resin is synthesized by reacting an acid component and an alcohol component with an equivalent ratio of an excess carboxyl group to a hydroxyl group, and then the carboxyl group in the carboxyl group-containing polyester resin is used by using the above alcohol component. A part of the above may be esterified. Further, the hydroxyl group-containing polyester resin may be first synthesized and then reacted with an acid anhydride to half-esterify the hydroxyl group-containing polyester resin.

During the esterification reaction or transesterification reaction, a catalyst may be used to accelerate the reaction. The catalyst is dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, tetraisopropyl titanate and the like.

The polyester resin may be modified with fatty acids, fats and oils, monoepoxy compounds, monoalcohol compounds, polyisocyanate compounds and the like during preparation, after esterification reaction or transesterification reaction.

Fatty acids include, for example, coconut oil fatty acid, cotton seed 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, flaxseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, dehydrated castor oil fatty acid. , Fatty acids such as saflower oil fatty acids; lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and the like.

Examples of fats and oils include palm oil, cottonseed oil, hemp seed oil, rice bran oil, fish oil, tall oil, soybean oil, flaxseed oil, tung oil, rapeseed oil, castor oil, dehydrated castor oil, safflower oil and the like.

The polyisocyanate compound used for the modification is not particularly limited. For example, the polyisocyanate compound is an aliphatic diisocyanate compound such as lysine diisocyanate, hexamethylene diisocyanate, or trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2, Alicyclic diisocyanate compounds such as 6-diisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,3- (isocyanatomethyl) cyclohexane; aromatic diisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate; Organic polyisocyanates such as trivalent or higher valent polyisocyanates such as lysine triisocyanates themselves, or additions of each of these organic polyisocyanates to polyhydric alcohols, low molecular weight polyester resins, water, etc., or each of the above-mentioned organic diisocyanates. (For example, isocyanurate), billet-type adduct, and the like. Polyisocyanate compounds may be used in combination.

Among the polyester resins, the coating composition of the present embodiment preferably contains the above-mentioned carboxyl group-containing polyester resin. By including the carboxyl group-containing polyester resin as the polyester resin, the obtained coating composition can form a coating film having more excellent smoothness and also excellent scratch resistance.

The number average molecular weight (Mn) of the polyester resin is not particularly limited. As an example, Mn is preferably 2000 or more, and more preferably 3000 or more. Further, Mn is preferably 30,000 or less, and more preferably 25,000 or less. When the Mn of the polyester resin is within the above range, the obtained coating film is excellent in coating film strength and processability, and tends to have good smoothness. In this embodiment, Mn is a value obtained by converting the number average molecular weight measured using a gel permeation chromatograph (GPC) with reference to the molecular weight of standard polystyrene. Specifically, "HLC8120GPC" (manufactured by Tosoh Corporation) is used as the gel permeation chromatograph, and "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL" are used as columns. And "TSKgel G-2000HXL" (manufactured by Tosoh Corporation) can be used for measurement under the conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow velocity 1 mL / min and detector RI.

The hydroxyl value of the polyester resin is not particularly limited. As an example, the hydroxyl value is preferably 10 mgKOH / g or more, and more preferably 20 mgKOH / g or more. The hydroxyl value is preferably 200 mgKOH / g or less, and more preferably 100 mgKOH / g or less. When the hydroxyl value is within the above range, the coating composition is excellent in scratch resistance and coating strength of the obtained coating film. In the present embodiment, the hydroxyl value is calculated by expressing the amount of potassium hydroxide required to acetylate the hydroxyl groups in the resin and neutralize the acetic acid required for acetylation by the number of mg per 1 g of the resin. Can be.

The acid value of the polyester resin is not particularly limited. As an example, the acid value is preferably 1 mgKOH / g or more, and more preferably 20 mgKOH / g or more. The acid value is preferably 200 mgKOH / g or less, and more preferably 100 mgKOH / g or less. When the acid value is within the above range, the coating composition is excellent in the processability of the obtained coating film. In the present embodiment, the acid value is calculated mathematically by the number of mg of potassium hydroxide theoretically required to neutralize 1 g of the resin based on the composition of the monomer used for synthesizing the resin. The theoretical acid value.

-Epoxy resin An epoxy resin is an organic compound having at least one epoxy group. The number of epoxy groups in the epoxy resin may be one or more per molecule, and preferably two or more. The number of epoxy groups per molecule is determined by dividing the total number of epoxy groups in the epoxy resin by the total number of molecules in the epoxy resin.

The epoxy resin is not particularly limited. For example, the epoxy resin is a bisphenol type epoxy resin, a novolak type epoxy resin, an aromatic epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin and the like.

Examples of the bisphenol type epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, bisphenol S type epoxy resin and the like, and bromines and water additives thereof. Examples of the novolak type epoxy resin include phenol novolac type epoxy resin and cresol novolak type epoxy resin. Examples of the aromatic epoxy resin include trisphenol methanetriglycidyl ether and the like.

The alicyclic epoxy resin includes 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-2-methylcyclohexylmethyl-3,4-epoxy-2-methylcyclohexanecarboxylate, Bis (3,4-epoxycyclohexyl) adipate, bis (3,4-epoxycyclohexylmethyladipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (3,4-epoxycyclohexyl-5,5) Examples thereof include 5-spiro-3,4-epoxycyclohexanone-meth-dioxane and bis (2,3-epoxycyclopentyl) ether.

The aliphatic epoxy resins include diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, and diglycidyl ether of polyethylene glycol. Examples thereof include diglycidyl ether of polypropylene glycol, polyglycidyl ether of long-chain polyol containing polyoxyalkylene glycol containing an alkylene group having 2 to 9 carbon atoms, polytetramethylene ether glycol, and the like.

The glycidyl ester type epoxy resin includes phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, diglycidyl-p-oxybenzoic acid, salicylic acid glycidyl ether-glycidyl ester, dimer acid glycidyl ester and the like. Is exemplified.

The glycidylamine type epoxy resin includes triglycidyl isocyanurate, N, N'-diglycidyl derivative of cyclic alkylene urea, N, N, O-triglycidyl derivative of p-aminophenol, and N, N, O- of m-aminophenol. Examples thereof include triglycidyl derivatives.

Among these, the epoxy resin is preferably a bisphenol type epoxy resin from the viewpoint that the formed coating film exhibits excellent adhesion, and at least one of the bisphenol A type epoxy resin and the bisphenol F type epoxy resin. It is more preferable that there is one. These epoxy resins may be used in combination.

From the viewpoint of adhesion, water resistance, and moisture resistance, the epoxy resin equivalent of the epoxy resin is preferably 100 g / equivalent or more, more preferably 150 g / equivalent or more, and further preferably 180 g / equivalent or more. preferable. The epoxy resin equivalent is preferably 2500 g / equivalent or less, more preferably 2200 g / equivalent or less, and even more preferably 2000 g / equivalent or less.

Resin solid content of the coating composition The content of the epoxy resin varies depending on the difference in the coating solid content, and is not unconditionally determined. As an example, the resin solid content in the coating composition is preferably 5 to 55% by weight. When the content of the epoxy resin is within the above range, the strength and adhesion of the formed coating film are likely to be enhanced.

The number average molecular weight (Mn) of the epoxy resin is not particularly limited. As an example, Mn is preferably 300 or more, and more preferably 800 or more. Further, Mn is preferably 10,000 or less, and more preferably 3000 or less. When the Mn of the epoxy resin is within the above range, the obtained coating film tends to have excellent coating film strength and processability, and also tends to have good smoothness.

-Acrylic resin The acrylic resin is an alkyl (meth) acrylate, an alkoxy acrylate, or the like. In addition, in this specification, "(meth) acrylic" includes "acrylate" and "methacrylate".

The alkyl (meth) acrylate is n-butyl acrylate, i-butyl acrylate, 2-ethylhexyl (meth) acrylate, isomyristyl acrylate, lauryl (meth) acrylate and the like. Alkoxy acrylates include methoxyethyl acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate and the like. Acrylic resin may be used in combination. Among these, the acrylic resin is preferably an alkyl (meth) acrylate from the viewpoints of reactivity, storage stability, weather resistance and the like.

The number average molecular weight (Mn) of the acrylic resin is not particularly limited. As an example, Mn is preferably 300 or more, and more preferably 1000 or more. Further, Mn is preferably 10,000 or less, and more preferably 5000 or less. When the Mn of the acrylic resin is within the above range, the storage stability is excellent, and the obtained coating film is excellent in coating film strength and processability, and tends to have good smoothness.

-Fluororesin Fluororesin is not particularly limited. As an example, the fluororesin includes polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and tetrafluoro. Examples thereof include ethylene / hexafluoropropylene / perfluoro (alkyl vinyl ether) copolymers, tetrafluoroethylene / ethylene copolymers, polyvinylidene fluoride, polychlorotrifluoroethylene, and chlorotrifluoroethylene / ethylene copolymers. Fluororesin may be used in combination.

Fluororesin can suppress the generation of pinholes when forming a coating film and has excellent smoothness. Therefore, it is a copolymer of PTFE, PFA, FEP, tetrafluoroethylene, hexafluoropropylene, perfluoro (alkyl vinyl ether), etc. Is preferable.

The alkyl group of perfluoro (alkyl vinyl ether) in PFA preferably has 1 to 5 carbon atoms, and is preferably perfluoro (propyl vinyl ether) (PPVE), perfluoro (ethyl vinyl ether) (PEVE), and perfluoro (methyl). More preferably, it is vinyl ether) (PMVE). The amount of perfluoro (alkyl vinyl ether) in PFA is preferably 1 to 50% by mass.

The number average molecular weight (Mn) of the fluororesin is not particularly limited. As an example, Mn is preferably 2000 or more, and more preferably 8000 or more. Further, Mn is preferably 30,000 or less, and more preferably 18,000 or less. When the Mn of the fluororesin is within the above range, the obtained coating film tends to have excellent coating film strength and processability, and also tends to have good smoothness.

(Hardener)
The curing agent is not particularly limited as long as it can react with the curable resin and form a cross-linking bond. For example, when the curable resin is a polyester resin, the curing agent is β-hydroxyalkylamide, glycidyl group-containing acrylic resin, epoxy resin, blocked isocyanate, TGIC (triglycidyl isocyanurate) or the like. Among these, the curing agent preferably contains at least one of β-hydroxyalkylamide, a glycidyl group-containing acrylic resin, and an epoxy resin from the viewpoint of a deblocking agent, and more preferably β-hydroxyalkylamide. preferable.

-Β-Hydroxyalkylamide The β-hydroxyalkylamide preferably has two or more functional groups per molecule from the viewpoint of excellent low-temperature curability and moisture resistance of the obtained coating film. Suitable β-hydroxyalkylamides are represented by the following general formula.

式中、ｎは１以上の整数である。Ｒはそれぞれ独立にＨまたはＣＨ₃である。ｎは、低温硬化性および粉体塗料組成物の耐ブロッキング性が優れる点から、３〜８であることが好ましく、４〜６であることがより好ましい。

In the formula, n is an integer of 1 or more. R is H or CH ₃ independently. n is preferably 3 to 8 and more preferably 4 to 6 from the viewpoint of excellent low-temperature curability and blocking resistance of the powder coating composition.

-Glysidyl group-containing acrylic resin The glycidyl group-containing acrylic resin is not particularly limited. As an example, in addition to the above-mentioned glycidyl group-containing acrylic resin, a glycidyl group-containing monomer such as glycidyl (meth) acrylicate and, if necessary, other vinyl-based monomers are subjected to a solution polymerization method or a massive polymerization method. , And those obtained by radical polymerization reaction by a known polymerization method such as suspension polymerization method.

Other vinyl-based monomers include, for example, hydroxyl group-containing monomers such as hydroxyl (meth) acrylate, carboxyl group-containing monomers such as (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate. (Meta) acrylic acid alkyl esters such as 2-ethylhexyl (meth) acrylate, aromatic vinyl compounds such as styrene and α-methylstyrene, (meth) acrylonitrile compounds, amino groups such as dimethylaminoethyl (meth) acrylate Containing monomers, vinyl-based monomers of carboxylic acids such as vinyl acetate, and the like.

The epoxy equivalent of the glycidyl group-containing acrylic resin is preferably 250 to 1500, more preferably 400 to 900.

The softening point of the glycidyl group-containing acrylic resin is preferably 50 ° C. or higher, more preferably 90 ° C. or higher. The softening point is preferably 130 ° C. or lower, more preferably 120 ° C. or lower. When the softening point is within the above range, the obtained coating composition is excellent in storage stability (blocking resistance) and fluidity. Further, the obtained coating film has excellent smoothness.

The number average molecular weight (Mn) of the glycidyl group-containing acrylic resin is preferably 300 or more, and more preferably 1000 or more. Further, Mn is preferably 10,000 or less, and more preferably 5000 or less. When Mn is within the above range, the obtained coating film has good coating film physical characteristics and excellent smoothness.

-Epoxy resin As the epoxy resin, any epoxy resin shown as a curable resin can be used. For example, a hybrid powder coating material can be obtained by using an epoxy resin as a curing agent for a curable resin containing a carboxyl group. Specifically, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, other glycidyl ether type epoxy resin, alicyclic epoxy resin and the like.

The glycidyl ether type epoxy resin is an epoxy resin having a glycidyl ether group that can be obtained by reacting a polyhydric alcohol, a polyhydric phenol or the like with epihalohydrin or an alkylene oxide.

Polyhydric alcohols include, for example, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, neopentyl glycol, butylene glycol, hexanediol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, diglycerin, sorbitol and the like.

The polyhydric phenol is, for example, 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 2,2-bis (2-hydroxyphenyl) propane, 2- (2-hydroxyphenyl) -2- (4). -Hydroxyphenyl) propane, halogenated bisphenol A, bis (4-hydroxyphenyl) methane [bisphenol F], tris (4-hydroxyphenyl) propane, resorcin, tetrahydroxyphenylethane, 1,2,3-tris (2, 3-Epoxypropoxy) Propane, novolak-type polyhydric phenol, cresol-type polyhydric phenol, etc. Among these, the epoxy resin is preferably a bisphenol A type epoxy resin derived from bisphenol A.

The glycidyl ester type epoxy resin is, for example, phthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, dimer acid diglycidyl ester and the like.

Other glycidyl ether type epoxy resins are, for example, tetraglycidylaminodiphenylmethane, triglycidyl isocyanurate and the like.

The alicyclic epoxy resin is, for example, (3,4-epoxy-6-methylcyclohexyl) methyl-3,4-epoxy-6-methylcyclohexanecarboxylate, (3,4-epoxycyclohexyl) methyl-3,4- Epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, Epolide GT300 (manufactured by Daicel Chemical Industries, Ltd., trifunctional alicyclic epoxy Resin), Epolide GT400 (manufactured by Daicel Chemical Industry Co., Ltd., tetrafunctional alicyclic epoxy resin), EHPE (manufactured by Daicel Chemical Industry Co., Ltd., polyfunctional alicyclic epoxy resin) and the like.

Further, the epoxy resin may be an epoxy group-introduced alkylphenol epoxy resin or an alkylnovolac phenol epoxy resin obtained by reacting an alkylphenol type resin or an alkylnovolacphenol type resin with epichlorohydrin.

Further, the epoxy resin may be a modified epoxy resin, for example, urethane-modified epoxy resin, acrylic-modified epoxy resin, fatty acid-modified epoxy resin, polyester-modified epoxy resin, terminal alkylphenol-modified epoxy resin, amine-modified epoxy resin, dimer acid. It may be a modified epoxy resin or the like.

The number average molecular weight (Mn) of the epoxy resin is preferably 300 or more, and more preferably 800 or more. Further, Mn is preferably 10,000 or less, and more preferably 3000 or less. When Mn is within the above range, the obtained coating film has good coating film physical characteristics and excellent smoothness.

Returning to the description of the curing agent as a whole, the content of the curing agent is not particularly limited. As an example, the content of the curing agent is such that the reactive group of the curing agent (hydroxyl group in the case of β-hydroxyalkylamide, epoxy in the case of epoxy resin) is compared with the carboxyl group or hydroxyl group which is the reactive group of the polyester resin. In the case of groups and blocked isocyanates, the molar ratio of (isocyanate groups, etc.) is preferably 50% or more, and more preferably 70% or more. Further, the content of the curing agent is preferably such that the molar ratio of the reactive group of the curing agent to the carboxyl group or the hydroxyl group which is the reactive group of the polyester resin is 150% or less, and more preferably 120% or less. .. When the content of the curing agent is within the above range, the obtained coating film has excellent coating film performance.

(Polyolefin wax)
The polyolefin wax may contain a polyolefin wax A having a melting point of 141 to 180 ° C. and a polyolefin wax B having a melting point of 90 to 140 ° C. As an example, the polyolefin wax is a (co) polymer ((co) polymerization) of an olefin (eg, ethylene, propylene, 1-butene, isobutylene, 1-hexene, 1-dodecene, 1-octadecene and mixtures thereof). (Including those obtained from Acids, monomethyl maleates, monobutyl maleates and dimethyl maleates) modified products), olefins and unsaturated carboxylic acids (such as (meth) acrylic acid, itaconic acid and maleic anhydride) or unsaturated carboxylic acid alkyl esters ((meth) ) Copolymers with alkyl acrylate (1-18 carbon atoms of alkyl) ester and alkyl maleate (1-18 carbon atoms of alkyl) ester, polymethylene (for example, Fischertropsh wax such as sasol wax) , Fatty metal salts (calcium stearate, etc.), fatty acid esters (behenyl behenate, etc.) and the like. The polyolefin wax A and the polyolefin wax B may be selected from these polyolefin waxes based on their melting points.

The polyolefin wax A has a high melting point and can impart excellent scratch resistance to the obtained coating film. On the other hand, the polyolefin wax B has a low melting point and can impart an excellent matting effect to the obtained coating film. By using these polyolefin waxes having different melting points in combination, the coating composition of the present embodiment obtains only the advantages of each, and imparts an excellent matting effect and scratch resistance to the obtained coating film. It is characterized by. Of these, polypropylene wax in which the polyolefin wax A may be modified is preferable, and polyethylene wax in which the polyolefin wax B may be modified is preferable.

The blending ratio (mass ratio) of the polyolefin wax A and the polyolefin wax B is not particularly limited. As an example, the blending ratio is preferably 10: 0.3 to 10:30, more preferably 10: 1 to 10: 5. When the blending ratio of the polyolefin wax A and the polyolefin wax B is within the above range, the obtained coating film can obtain good scratch resistance and a matting effect.

The mixing ratio (mass ratio) of the curable resin and the polyolefin wax is not particularly limited. As an example, the blending ratio is preferably 100: 6 to 100: 20, more preferably 100: 6 to 100: 15. When the blending ratio of the polyester resin and the polyolefin wax is within the above range, the resulting coating composition can be adjusted in gloss in the range of semi-matte to matte, and a coating film showing excellent smoothness can be obtained. can get.

Next, the components preferably contained in the coating composition of the present embodiment will be described.

(Wax (excluding polyolefin wax))
The coating composition may contain waxes other than the above-mentioned polyolefin wax. The wax is not particularly limited. As the wax, animal, vegetable, mineral natural wax, or synthetic wax is appropriately used. Synthetic waxes are reaction products of long-chain alcohols such as aliphatic amine waxes, palmityl alcohols and stearyl alcohols obtained by the reaction of hydrogenated castor oil with monoethanolamine and acids such as palmitic acid and myristic acid. Examples thereof include fatty acid ester waxes such as fatty acid glycerides, glycol esters, and amide waxes. Examples of natural wax include Japanese wax, carnaupa wax, shellac wax, paraffin wax and the like.

(Constitution pigment)
The coating composition is preferably blended with an extender pigment. The extender pigment is not particularly limited. As an example, the extender pigment is barium sulfate, barium carbonate, calcium carbonate, clay, silica powder, diatomaceous earth, talc, basic magnesium carbonate, alumina white and the like. Among these, from the viewpoint of smoothness, the extender pigment is preferably calcium carbonate or precipitated barium sulfate.

The blending amount of the extender pigment is not particularly limited. As an example, the extender pigment is preferably blended in an amount of 60 parts by mass or less, and more preferably 40 parts by mass or less, based on 100 parts by mass of the polyester resin. When the blending amount exceeds 60 parts by mass, the obtained coating composition tends to be inferior in smoothness.

(Other optional ingredients)
The coating composition of the present embodiment may be appropriately blended with other optional components usually used in the coating composition. Such optional components include plasticizers, curing accelerators, cross-linking catalysts, surface conditioners, UV absorbers, light stabilizers, antioxidants, fluidity conditioners, anti-dripping agents, antifoaming agents, and matting agents. Examples thereof include agents, coloring pigments, rust preventive pigments, brilliant pigments, fluidity adjusting agents, blocking inhibitors, armpit inhibitors, charge control agents, curing accelerators and the like.

The method for producing the coating composition of the present embodiment is not particularly limited. The coating composition can be produced by a conventionally known method. As an example, a coating composition can be produced by melting and mixing each component, then cooling and pulverizing. The particle size of the obtained coating composition is adjusted to about 10 μm to 80 μm in terms of volume average particle size.

As described above, the coating composition of the present embodiment is a coating film having excellent smoothness, arbitrary gloss adjustment, and excellent scratch resistance by using a plurality of polyolefin waxes having different melting points in combination. Can be formed.

<Painted products and manufacturing methods for painted products>
The coated product of one embodiment of the present invention includes a base material and a coating film layer formed on the base material by the above coating composition.

The base material is not particularly limited. For example, the base material is an iron-based metal such as iron or stainless steel, or a non-ferrous metal such as aluminum, magnesium, zinc, or an alloy thereof. Examples of the iron-based base material include cold-rolled steel sheets, hot-rolled steel sheets, and stainless steel sheets. Examples of the non-ferrous metal base material include aluminum steel plate, zinc steel plate, magnesium alloy, aluminum-zinc alloy, zinc-nickel-plated steel plate, zinc-chrome-plated steel plate, zinc-magnesium-plated steel plate and the like. These base materials are used for various electric appliances, automobile parts (aluminum wheels, etc.), building materials, structures, office equipment, and the like.

The manufacturing method of the painted product is not particularly limited. As an example, a coated product can be produced by applying a coating composition to the above-mentioned base material to form a coating film. The painting method is not particularly limited. As the coating method, a known method such as an electrostatic coating method, a flow immersion method, a spraying method, or an in-mold method is adopted. Among these, the coating method is preferably an electrostatic powder coating method using a powder coating gun. In the electrostatic powder coating method, when the base material is a metal material, after touching the base material, a powder coating composition is used by using a powder coating device such as a corona charging type coating gun or a friction charging type coating gun. Is a method of spraying.

When a corona charging type coating gun is used, the load voltage applied to the coating composition by the corona discharge treatment is about -50 to -100 KV. On the other hand, when a triboelectric coating gun is used, the internally generated current value of the coating composition is about 1.0 to 8.0 μA. The preferable discharge rate of the coating gun is about 50 to 400 g / min, and the discharge pressure is about 4.9 × 10 ^{4 to} 4.9 × 10 ⁵ Pa. Further, the distance from the tip of the coating gun to the base material is about 10 to 50 cm. As a result, the particles of the coating composition can be efficiently applied and electrostatically adhered to the base material to easily form a coating film. As a result, a coating film having excellent smoothness, optionally adjusting gloss, and various coating film performances can be formed in the obtained coated product.

The thickness of the coating film layer is not particularly limited. As an example, the thickness of the coating film layer is preferably 30 to 120 μm, more preferably 50 to 100 μm. When the thickness of the coating film layer is within the above range, excellent smoothness and coating film performance can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%" and "part" means "parts by mass".

The raw materials used are shown below.
<Polyester resin>
-Carboxyl group-containing polyester resin Urarac P785 (acid value: 32 to 38 mgKOH / g manufactured by DSM Japan Co., Ltd.)
Urarac P821 (acid value: 20-24 mg KOH / g manufactured by DSM Japan Co., Ltd.)
Urarac P886 (Acid value: 33-37 mgKOH / g manufactured by DSM Japan Co., Ltd.)
CRYLCOT AT 2671-3 (acid value: 50 mgKOH / g manufactured by Daicel Ornex Co., Ltd.)
CRYLCOAT 1540-0 (acid value: 70 mgKOH / g manufactured by Daicel Ornex Co., Ltd.)
-Hydroxy group-containing polyester resin Yupica Coat GV-570 (acid value: 4 mgKOH / g manufactured by Japan U-Pica Co., Ltd.)
<Hardener>
・ HAA
Primid XL-552 (manufactured by Ems-Chemie Japan Co., Ltd.)
Primid QM-1260 (manufactured by Ems-Chemie Japan Co., Ltd.)
-Epoxy resin D. E. R 662-E (bisphenol A type epoxy resin, epoxy equivalent 590-630, manufactured by OLIN)
・ Acrylic resin containing glycidyl group Finedick A261 (manufactured by DIC Corporation)
・ Block Isocyanate Arcure 4470 (manufactured by Polynt)
<Polyolefin wax>
・ Polyolefin wax A
CERAFLOUR 970 (polypropylene wax, melting point: 160 ° C)
Ceridust 6050M (polypropylene wax, melting point: 142-148 ° C)
・ Polyolefin wax B
CERAFLOUR 950 (modified high density polyethylene wax, melting point: 135 ° C)
AC A12 (high density polyethylene oxide wax, melting point: 121 ° C)
AC 573A (maleic acid copolymerized polyethylene wax, melting point: 106 ° C)
<Additives>
Resiflow P67 (Acrylic leveling agent, manufactured by ESTRON)
CERAFLOUR 993 (Amide Wax, manufactured by Big Chemie Japan)
PP-360 (phosphorus catalyst, manufactured by Keiai Kasei Co., Ltd.)
Benzoin (armpit inhibitor)
<Coloring pigment>
TiONA 595 (titanium oxide, manufactured by CRISTAL)
SPECIAL BLACK 4 beads (carbon black, manufactured by Orion Engineered Carbons)
<Constitution pigment>
R-50A (calcium carbonate, manufactured by Maruo Calcium Co., Ltd.)
Barium sulphate BA (barium sulphate sulphate, manufactured by Sakai Chemical Industry Co., Ltd.)

(Examples 1 to 18, Comparative Examples 1 to 10)
Each raw material was stirred and mixed according to the formulation shown in Table 1 or Table 2 to obtain a coating composition. The obtained coating composition was applied to a steel substrate by corona-type electrostatic powder coating so that the film thickness would be about 70 μm after drying, and then baked and dried at 165 ° C. for 20 minutes. The substrate was prepared by leaving it for 1 hour. After that, each evaluation was performed according to the following evaluation methods and evaluation criteria. The results are shown in Table 1.

<Gloss value>
The 60 ° mirror surface gloss was measured according to JIS K 5600-4-7. The case where the gloss value was 45 or less was regarded as acceptable.

<Scratch resistance>
Using a Gakushin type wear tester, the coating film was rubbed with an object to be coated with three layers of white cloth cotton (gold width No. 3) attached for testing under a load of 500 g and a number of reciprocations of 1000 times. The gloss values before and after the test were measured and compared by the above-mentioned method for measuring the gloss value. If the change in gloss value was within 10, it was passed, and if it was greater than 10, it was rejected.

<Smoothness>
The smoothness of the coating film was visually evaluated.
(Evaluation criteria)
⊚: Smoothness was very good.
◯: Smoothness was good.
X: Smoothness was inferior.

As shown in Table 1, the coating compositions of Examples 1 to 18 in which the polyolefin wax A having a high melting point and the polyolefin wax B having a low melting point are used in combination can all achieve a wide range of gloss values. Moreover, it has excellent scratch resistance and smoothness.

On the other hand, as shown in Table 2, the coating compositions of Comparative Examples 1 to 10 in which at least one of the polyolefin wax A having a high melting point and the polyolefin wax B having a low melting point was not blended were matte. The effect was low, or the scratch resistance and smoothness were inferior.

Claims (7)

Contains a curable resin, a curing agent, and a polyolefin wax,
The curable resin contains a polyester resin and contains
The polyester resin contains at least one of a carboxyl group-containing polyester resin and a hydroxyl group-containing polyester resin.
The polyolefin wax contains a polyolefin wax A having a melting point of 141 to 180 ° C. and a polyolefin wax B having a melting point of 90 to 140 ° C.
The mixing ratio (mass ratio) of the polyolefin wax to the curable resin is 6 or more of the polyolefin wax with respect to the curable resin 100.
The blending ratio (mass ratio) of the polyolefin wax A and the polyolefin wax B is 10: 0.3 to 10:30.
The curing agent is a matte powder coating composition containing at least one of β-hydroxyalkylamide, a glycidyl group-containing acrylic resin, and an epoxy resin. The polyester resin comprises a carboxyl group-containing polyester resin according to claim 1, matte powder coating composition. The matte powder coating composition according to claim 1 or 2, wherein the acid value of the polyester resin is 1 mgKOH / g or more and 200 mgKOH / g or less. The matte powder coating composition according to any one of claims 1 to 3, wherein the polyester resin has a hydroxyl value of 10 mgKOH / g or more and 200 mgKOH / g or less. The matte powder coating composition according to any one of claims 1 to 4 , wherein the mixing ratio (mass ratio) of the curable resin and the polyolefin wax is 100: 6 to 100:20. The matte powder coating composition according to any one of claims 1 to 5, wherein the curing agent contains β-hydroxyalkylamide. A coated product comprising a base material and a coating film layer formed on the base material by the matte powder coating composition according to any one of claims 1 to 6.