JP4708720B2 - Thermosetting powder coating for wheel, method for forming coating film using the coating, method for manufacturing the coated product, and coated product - Google Patents

Description

The present invention relates to a thermosetting powder coating material for a wheel, a method for forming a coating film using the coating material, a manufacturing method for the coated product, and a coated product. More specifically, it is possible to form a corrosion-resistant coating film having excellent finished appearance with excellent design properties (top coat adhesion, smoothness, etc.), free from repellency and dents due to contamination.

Among automotive parts, an aluminum wheel is a product that requires a high degree of anticorrosion and excellent design. However, for the purpose of protection and aesthetics, for example, an aluminum wheel is usually a thermosetting powder. After a primer is applied and cured by heating, a thermosetting acrylic solvent-based paint is applied as a top coat. In addition, an aluminum wheel having a cutting glitter design is usually coated with a thermosetting acrylic solvent-based paint with a glittering thermosetting paint as a top coat after, for example, coating with a thermosetting powder primer and heating and curing. After curing, cutting is performed. Again, a thermosetting clear paint is applied.

  In the method of forming a coating film for an aluminum wheel, it is particularly important to form a coating film having excellent smoothness and sharpness. When it is composed of multiple layers, it is baked together with the composition of each paint. Conditions and film thickness must also be appropriate. For example, an epoxy-polyester hybrid powder coating is used as a primer, an acrylic high solid metallic coating is used as a base coat layer, and an acrylic powder clear is applied as a top coat (Patent Document 1), and similar methods. A method of using an acrylic high solid paint for the top coat instead of the acrylic powder clear is known (Patent Document 2).

  In addition, when different types of paint are mixed in the powder coating, there is a problem in that the coating film formed has a coating surface abnormality such as so-called repellency or dents, and the appearance of the coating is impaired. A powder coating composition that prevents appearance deterioration is known (Patent Document 3).

JP-A-5-202319

Japanese Patent Laid-Open No. 5-209141 JP-A-5-186721

In the methods described in Patent Documents 1 and 2, usually, when an electrostatic powder coating machine is used to coat a metal material having many uneven portions such as an aluminum wheel, the coating film thickness becomes uneven and the film thickness is thin. The part generates coating film defects such as repellency and dents, and the coating film has poor smoothness. Such problems can be improved to some extent by increasing the coating film thickness, but conversely, coating film defects such as sagging occur on the coating film, making it difficult to maintain a balance between the two.
In addition, the powder coating described in Patent Document 3 improves coating surface abnormalities such as repellency and dents, but in this case, for example, the finished appearance and coating film performance (especially corrosion resistance) are highly required. It is not suitable for the use of aluminum wheels.

    An object of the present invention is to provide a powder primer, particularly for an aluminum wheel, excellent in finished appearance and corrosion resistance.

  The thermosetting powder coating for wheels according to the present invention is characterized by containing a carboxyl group-containing thermosetting polyester resin (A), an epoxy resin (B), and a hydroxyl group-containing polymer (C).

  The thermosetting powder coating material for wheels according to the present invention further includes a phosphate ester compound having at least one P—OH bond obtained by reacting a monoglycidyl ether compound and / or a monoglycidyl ester compound with phosphoric acid ( It is preferable to contain a phosphoric acid-modified epoxy resin (D) obtained by reacting a) with an epoxy compound (b) having one or more epoxy groups in the molecule.

    The coating film forming method according to the present invention is characterized in that the thermosetting powder coating for a wheel is coated with an electrostatic powder on an aluminum wheel to form a powder primer layer.

  In the method for forming a coating film according to the present invention, a colored base coating film layer is formed on the surface of the primer layer.

  In the method for forming a coating film according to the present invention, a top clear layer is formed on the surface of the colored base layer.

  A method for producing a coated product according to the present invention is a method for producing a product coated with a powder coating, and the powder thermosetting powder coating is applied to an aluminum wheel by electrostatic powder coating to form a powder primer. The method includes a step of forming a layer.

  The production method according to the present invention includes a step of forming a colored base coating film layer on the surface of the primer layer.

  The manufacturing method according to the present invention includes a step of forming a top clear layer on the surface of the colored base layer.

  The coated product according to the present invention is manufactured by the method.

In the present invention, it is presumed that by containing a hydroxyl group-containing polymer, the hydroxyl group-containing polymer is orientated on the surface of the coating film during baking, thereby improving repelling resistance against different powder coating materials.
Further, the hydroxyl group improves wettability with respect to a top coat such as a solution-type paint, and improves the adhesion to the top coat and the finished appearance.

In the present invention, by adding a specific phosphoric acid-modified epoxy resin, the adhesion between the aluminum wheel and the powder primer is increased, and the corrosion resistance and chipping resistance are improved.
In addition, the phosphoric acid epoxy resin was involved in the crosslinking reaction with the carboxyl group-containing thermosetting polyester resin, and it was thought that the adhesion force of the coating film was increased by the bonding force between the phosphoric acid group and the aluminum wheel base material. It is done.

The thermosetting powder coating material for wheels of the present invention comprises a carboxyl group-containing thermosetting polyester resin (A) (hereinafter sometimes simply referred to as “polyester resin (A)”), an epoxy resin (B), and a hydroxyl group. Contains the containing polymer (C).
The polyester resin (A) used in the powder coating of the present invention is a base resin component constituting the powder coating of the present invention, and the carboxyl group in the resin is an epoxy resin (B) when the coating film is baked. It reacts with the epoxy group in the epoxy group and the epoxy group in the phosphoric acid-modified epoxy resin (D) to form a cured coating film.
The number average molecular weight of the polyester resin (A) is 400 to 20,000, preferably 1,000 to 15,000. If it is less than 400, the mechanical properties deteriorate, and if it exceeds 20,000, the smoothness of the coating film decreases, which is not preferable.

  Moreover, the softening temperature of a polyester resin (A) is 30-140 degreeC, Preferably, it is 40-100 degreeC. When the softening temperature is less than 30 ° C., the powder coating particles are fused to each other during storage of the powder coating material, causing the coating film to be fuzzy. Moreover, since the smoothness of a coating film will fall when it exceeds 140 degreeC, it is unpreferable.

  The acid value of the polyester resin (A) is preferably in the range of 10 to 200 mgKOH / g, particularly 20 to 150 mgKOH / g. When the acid value is less than 10 mgKOH / g, the curability is lowered, and as a result, the coating performance such as water resistance, corrosion resistance, and chipping resistance is deteriorated. On the other hand, when the acid value exceeds 200 mgKOH / g, the coating film is hydrophilic. The water resistance and anticorrosion properties are reduced due to the increase in properties.

  Examples of the polyester resin (A) include (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, dimethyl isophthalate, dimethyl terephthalate, hexahydro (anhydrous) phthalic acid, tetrahydro (anhydrous) phthalic acid, adipic acid, sebacic acid and the like. Aromatic, alicyclic or aliphatic dicarboxylic acids and (poly) ethylene glycol, (poly) propylene glycol, butylene glycol, neopentyl glycol, 1,6-hexanediol, dihydric alcohols such as dimethylpropionic acid, If necessary, monocarboxylic acid such as benzoic acid, trivalent or higher carboxylic acid such as (anhydrous) trimellitic acid, trivalent or higher alcohol such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol and the like. React appropriately so that it is in the above-mentioned acid value range. Resin obtained.

  In the epoxy resin (B) used in the present invention, an epoxy group in the resin reacts with a carboxyl group in the polyester resin (A) to form a cured coating film. As the epoxy resin (B), a basic solid resin having a softening point of 50 to 140 ° C., an epoxy equivalent of 200 to 6,000, and a number average molecular weight of 800 to 10,000 is preferably used. Specifically, as trade names, for example, Epicoat 1001, Epicoat 1002, Epicoat 1004, Epicoat 1007 manufactured by Japan Epoxy Resin Co., Ltd., Araldite GY-6084, Araldite GY-6097 manufactured by Ciba-Geigy, Dow Chemical Company Bisphenol / epichlorohydrin type epoxy resin such as DER-662, DER-664, DER-667, Adeka Resin EP-4100 (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.) manufactured by Nippon Kayaku Co., Ltd., Examples thereof include novolak type epoxy resins such as EPPN-202 and EOCN-1020. In the present invention, one or a combination of two or more selected from these can be used, but is not limited thereto.

  The compounding ratio of the epoxy resin (B) is 3 to 150 parts by weight, preferably 10 to 120 parts by weight with respect to 100 parts by weight of the polyester resin (A). If the amount is less than 3 parts by weight, the curability is lowered, so that the water resistance and corrosion resistance of the coating film are inferior. If the amount exceeds 150 parts by weight, an unreacted epoxy resin not involved in the crosslinking reaction remains in the coating film. , Water resistance, corrosion resistance and chipping resistance are reduced.

  As the hydroxyl group-containing polymer (C) used in the present invention, a conventionally known polymer can be used as long as it is a polymer having an average of one or more hydroxyl groups in one molecule.

  The hydroxyl group-containing polymer (C) is a homopolymer of a hydroxyl group-containing radical polymerizable unsaturated monomer or a copolymer of the monomer and other radical polymerizable unsaturated monomer as required. Is included.

  Examples of the hydroxyl group-containing radical polymerizable unsaturated monomer include acrylic acid or methacrylic acid having 2 carbon atoms such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate. Hydroxyalkyl esters of -8; monoesters of polyether polyols such as polyethylene glycol, polypropylene glycol and polybutylene glycol and unsaturated carboxylic acids such as (meth) acrylic acid; alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide And adducts of hydroxyl group-containing unsaturated monomers such as 2-hydroxyethyl (meth) acrylate; acid anhydride group-containing unsaturated compounds such as maleic anhydride and itaconic anhydride; ethylene glycol; Monoester or diesterified products with glycols such as sundiol and neopentyl glycol; hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether; allyl alcohol and the like; α, β-ethylenically unsaturated carboxylic acid and Cardura E10 (Shell Petroleum) Adducts of mono-epoxy compounds such as Chemical Co., Ltd. (trade name) and α-olefin epoxides; Glycidyl (meth) acrylate and acetic acid, propionic acid, p-tert-butylbenzoic acid, monobases such as fatty acids Examples include adducts with acids; adducts of the above hydroxyl group-containing monomers and lactones (for example, ε-caprolactone, γ-valerolactone). These monomers can be used alone or in combination of two or more. Among these, (meth) acrylate unsaturated monomers are particularly preferable, and 2-hydroxyethyl (meth) acrylate and 3-hydroxypropyl (meth) acrylate are more preferable.

  Other radical polymerizable unsaturated monomers include, for example, vinyl aromatic compounds such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) C1-C24 alkyl ester or cyclic alkyl ester of acrylic acid or methacrylic acid such as acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, etc. Raising It is.

The hydroxyl group-containing polymer (C) is particularly preferably a copolymer, and the blending ratio of the hydroxyl group-containing radically polymerizable unsaturated monomer is 5 to 40% by weight based on the monomer constituting the copolymer. It is preferable to use in the range, and more preferable to use in the range of 10 to 30% by weight.
In the region where the hydroxyl group-containing radical polymerizable unsaturated monomer exceeds the above range, the finished appearance such as the smoothness of the coating film is deteriorated.

The number average molecular weight of the hydroxyl group-containing polymer (C) is preferably in the range of 1,000 to 10,000, particularly 2,000 to 6,000. When the number average molecular weight is less than 1,000, the coating performance such as solvent resistance and acid resistance is lowered. On the other hand, when the number average molecular weight exceeds 10,000, the finished appearance such as the smoothness of the coating is lowered. It is not preferable.
The blending ratio of the hydroxyl group-containing polymer (C) is preferably 0.1 to 20 parts by weight, particularly 0.5 to 15 parts by weight, based on 100 parts by weight of the total amount of the components (A) and (B). preferable. When the blending amount is less than 0.1 parts by weight, coating film defects such as repellency and dents are likely to occur, and the effect of improving the wettability with respect to the top coat is not obtained, so that the finished appearance and adhesion are reduced. When it exceeds, sclerosis | hardenability will fall.

The phosphoric acid-modified epoxy resin (D) used in the present invention is a phosphoric acid ester compound (a) having at least one P-OH bond obtained by reacting a monoglycidyl ether compound and / or a monoglycidyl ester compound with phosphoric acids. ) And an epoxy compound (b) having one or more epoxy groups in the molecule.
The monoglycidyl ether compound is a compound represented by the following general formula (I), and the monoglycidyl ester compound is a compound represented by the following general formula (II).

In the general formulas (I) and (II), examples of the alkyl group represented by R and R ′ include methyl, ethyl, propyl, butyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, Examples include linear or branched alkyl groups such as tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, behenyl, etc. As the alkenyl group, 1 to 3 unsaturated bonds in the above alkyl group The aryl group includes, for example, a phenyl group, a naphthyl group, etc., and these aryl groups may be substituted with 1 to 3 of the above alkyl groups. Together can form a ring.

  The monoglycidyl ether compound represented by the above general formula (I) and the monoglycidyl ester compound represented by the above general formula (II) can be easily prepared from epichlorohydrin and alcohols, phenols or organic carboxylic acids by a conventional method. It can be obtained.

  Examples of the monoglycidyl ether compound represented by the general formula (I) include methyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, sec-butylphenyl glycidyl ether, 2-methyloctyl glycidyl ether, and octadecyl. Examples thereof include glycidyl ether, phenyl glycidyl ether, tolyl glycidyl ether, and octylphenyl glycidyl ether.

  Examples of the monoglycidyl ester compound represented by the general formula (II) include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, 2-ethylhexylic acid, Neodecanoic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, isostearic acid, stearic acid, 12-hydroxystearic acid, behenic acid, montanic acid, acrylic acid, methacrylic acid, crotonic acid, Glycidyl of monovalent carboxylic acids such as elaidic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, toluic acid, dimethylbenzoic acid, ethylbenzoic acid, cumic acid, n-propylbenzoic acid An ester compound is mentioned.

  Examples of the phosphoric acids include orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, phosphorous acid, polyphosphoric acid, phosphonic acid, methanephosphonic acid, benzenephosphonic acid, 1-hydroxyethane-1, 1-diphosphonic acid, and phosphinic acid. Is mentioned.

  When obtaining the phosphoric acid ester compound as the component (a), the phosphoric acid and the monoglycidyl ether compound represented by the general formula (I) or the monoglycidyl ester compound represented by the general formula (II) are: The epoxy group (epoxy equivalent) of the compound of the general formula (I) or (II) is 0.1 to 0.9 equivalent, preferably 0.3 to 0 with respect to 1 equivalent of the P—OH group of the phosphoric acid. Used in an amount of 8 equivalents. Here, if the epoxy group is less than 0.1 equivalent, excess phosphoric acid and the epoxy compound which is component (b) described below may react and gel, and if it exceeds 0.9 equivalent Is not preferable because denaturation becomes difficult.

  As the epoxy compound (b) used in the phosphoric acid-modified epoxy resin (D), a resin having two or more epoxy groups in one molecule and known per se can be used. Specifically, glycidyl ethers of an epihalohydrin such as epichlorohydrin and an aliphatic polyhydroxy compound (for example, glycol or glycerin); an epihalohydrin such as epichlorohydrin and an aromatic polyhydroxy compound (for example, bisphenol A, bisphenol F, novolac phenol, Glycidyl ethers such as cresolphenol; Glycidyl ethers of epihalohydrins such as epichlorohydrin and alicyclic polyhydroxy compounds such as hydrogenated bisphenol A; Epihalohydrins such as epichlorohydrin and aromatic polycarboxylic acid compounds such as Glycidyl ethers with phthalic acid, etc .; epoxidized oils; alicyclic epoxy resins;

  The blending ratio of the phosphoric acid ester compound (a) constituting the phosphoric acid-modified epoxy resin (D) is not particularly limited as long as the epoxy group remains in the adduct, but usually the epoxy compound (b It is preferable that the P—OH group of the phosphate ester compound (a) is 0.01 to 0.8 equivalent, particularly 0.03 to 0.5 equivalent with respect to 1 equivalent of the epoxy group of . When the P—OH group of the phosphate ester compound (a) is less than 0.01 equivalent, the effect due to the addition of phosphoric acid is hardly exhibited, and when it exceeds 0.8 equivalent, the water resistance of the coating film is low. May fall.

  The phosphoric acid-modified epoxy resin preferably has a number average molecular weight of 300 to 2,000 and an epoxy equivalent of 150 to 2,100.

  The mixing ratio of the phosphoric acid-modified epoxy resin (D) is 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total amount of the polyester resin (A) and the epoxy resin (B). It is. When the amount is less than 0.5 part by weight, the adhesion to the substrate is lowered, and when it exceeds 30 parts by weight, the water resistance of the coating film is lowered.

  In the powder coating material of the present invention, in addition to the components (A) to (D), if necessary, coloring pigments, extender pigments, other fillers, curing catalysts, fluidity modifiers, anti-repellent agents, anti-waxing agents, ultraviolet rays Absorbers, light stabilizers and the like can be blended.

  The powder coating material of the present invention is produced by a conventional method, for example, by blending the above components (A) to (D), dry blending with a mixer, heating and melt-kneading, coarse pulverization, fine pulverization, and classification. it can.

The average particle size of the powder coating material thus produced is preferably 10 to 100 μm, and particularly preferably 15 to 40 μm from the viewpoint of coating film smoothness.
The minimum melt viscosity of the powder coating material of the present invention is preferably 0.5 to 200 Pa · s, and more preferably 0.5 to 20 Pa · s from the viewpoint of coating film smoothness.

  In the present specification, the number average molecular weight is a polystyrene-based number average molecular weight measured by gel permeation chromatograph (GPC).

  In this specification, the softening temperature is raised at a rate of temperature rise of 3 ° C./min in a glycerin heating bath using, for example, a ring and ball automatic softening point tester (manufactured by Meiho Co., Ltd.), and the sample is softened. It can be measured as the temperature (° C) when the sphere falls.

  In the present specification, the average particle diameter can be measured by using Microtrac 9220FRA, Microtrac HRA, etc. manufactured by Nikkiso Co., Ltd. The average particle diameter refers to a particle size (D50) value of 50% integrated value from the small particle diameter side.

  In the present specification, the minimum melt viscosity is the lowest melt viscosity exhibited by the paint when each component in the paint is melted by heat in the stage of heat-curing after applying the powder paint. Such minimum melt viscosity can be measured by a concentric viscoelasticity measuring device such as a solid liquid meter MR-300 (manufactured by Rheology).

  The method for forming a coating film of the present invention is a method for forming a powder primer layer by electrostatically coating an aluminum wheel with the thermosetting powder coating material for wheels of the present invention.

The aluminum wheel is subjected to a degreasing process for removing oil using an alkaline, acid or solvent-based degreasing agent when adhesion of oil or the like is assumed, and then, if necessary, phosphoric acid chromate treatment or chromium As a chromate treatment or a non-chromium treatment such as chromate treatment, it was treated with a metal such as titanium, zirconium, vanadium, zinc, silica, or a complex metal phosphate, sulfate, nitrate, hydrofluorate, etc. It is possible to use a material that has been thoroughly washed with deionized water and dried.
For electrostatic powder coating, a conventionally known electrostatic powder coating machine, for example, a corona discharge type coating machine, a frictional electrostatic type coating machine or the like can be used.

  The film thickness of the powder primer layer is 30 μm to 200 μm, preferably 50 to 110 μm, as the powder film thickness after baking. When the thickness is less than 30 μm, the smoothness is lowered, and appearance defects such as noticeable dust are likely to occur. In the case of a film thickness exceeding 200 μm, the occurrence of wrinkles and rough skin due to electrostatic repulsion may occur.

  Baking is performed by maintaining the surface temperature of the aluminum wheel at 120 to 200 ° C, preferably 140 to 170 ° C for 10 to 60 minutes.

  In the coating film forming method of the present invention, a colored base coating film layer can be formed on the surface of the primer layer. This colored base coating film layer can impart design properties by forming a coating film made of a colored base paint as an overcoating film on an aluminum wheel. In the case of outdoor use, the colored base paint is affected by ultraviolet rays, water, and heat, and therefore a resin excellent in weather resistance is desirable as a film-forming resin. For example, an acrylic thermosetting resin, Polyester-based thermosetting resin, acrylic-polyisocyanate-curing resin, etc. The form of the paint may be a solvent-type paint, or may be a water-based paint, a powder paint, or a one-part paint. May also be a two-component paint.

  Colored pigments and glitter pigments that can exhibit design properties are blended in the colored base paint. Examples of the colored pigments include titanium dioxide, iron oxide, petal, carbon black, phthalocyanine blue, phthalocyanine green, and quinacridone. Pigments, isoindoline pigments, azo pigments, acetolone pigments, various fired pigments and the like can be mentioned, but there is no particular limitation.

Moreover, a coloring pigment may be used together with a luster pigment as needed.
The glitter pigment is not particularly limited as long as it reflects received light and gives gloss to the coating film. Preferred examples thereof include metal powder such as aluminum powder, metal flake such as stainless steel flake, and mica. And micacious iron oxide (MIO, scaly iron oxide), glass flakes, colored pearl pigments, and one or more selected from the group consisting of pearl pigments.

As for the formation method of the colored base coating film, in the case of a liquid paint such as a solvent type or water, it is generally applied by spraying, and in the case of a powder paint, it is applied by an electrostatic powder coating method. In the baking type liquid paint, baking is performed at 120 to 160 ° C., and the film thickness after baking is 10 to 50 μm.
In the method for forming a coating film of the present invention, a top clear layer can be formed on the surface of the colored base layer. The top clear layer can provide excellent weather performance, excellent finished appearance with high gloss, excellent scratch resistance, chemical resistance and the like.

  As a paint for forming the top clear layer, an acrylic solvent-type clear paint that is usually used as a top coat in automobile bodies, automobile parts, etc. (for example, ALC-100 clear, acid epoxy curable organic solvent-type paint made by Kansai Paint) , Acrylic solvent-type high solid clear and two-component hydroxyl group-containing acrylic polyisocyanate curable resin clear paint (for example, Super Diamond Clear Q, manufactured by Kansai Paint), UV curable paint, acrylic powder paint (for example, Kansai) Paint, EVA Clad No. 5600DK, epoxy group-containing acrylic resin-dodecane diacid curable acrylic powder coating) can be used.

  When the paint used as the top clear is a solvent-type clear paint, the coating film forming resin is generally a hydroxyl group-containing acrylic-melamine curable resin and is usually applied by spray coating. Baking is held at 120-160 ° C. for 10-40 minutes. The film thickness after drying is 20-50 μm.

  In the case of an acrylic solvent-type clear made of a two-component hydroxyl group-containing acrylic polyisocyanate curing resin, low temperature curing at 60 to 80 ° C. is possible. It is applied by spray coating so that the dry film thickness is 20 to 50 μm.

The ultraviolet curable coating can be cured in a short time by irradiation with ultraviolet rays of 10 to 400 mJ / cm ² . In the UV curable paint, a functional group that is crosslinked by UV irradiation and a functional group that is crosslinked by heat can be used in combination. It is applied by spray coating so that the dry film thickness is 20 to 50 μm.

  When an epoxy group-containing acrylic resin dodecane diacid curable acrylic powder coating (for example, product name, EVA Clad No. 5600DK, manufactured by Kansai Paint Co., Ltd.) is used as the top clear, there is no discharge of harmful organic solvents and the powder Including the primer, a method for forming a coating film with less organic solvent discharge is obtained. In addition, similar to the powder primer, since it can be recovered and reused, the use efficiency is high and the economic effect is great.

The coating thickness of the powder top clear is 50 to 150 μm, preferably 70 to 110 μm, in terms of the thickness after heating. Moreover, baking is normally 140 to 180 degreeC for 10 to 40 minutes.
The method for producing a coated product according to the present invention comprises a step of forming the powder primer layer by coating the aluminum wheel with the thermosetting powder coating for a wheel according to the present invention on the aluminum wheel. It is. The formation of the powder primer layer can be carried out by the same method as described in the method for forming the powder primer layer.

  In the method for producing a coated product of the present invention, the colored base coating is formed by coating the surface of the powder primer layer coated with the thermosetting powder coating for a wheel of the present invention on the aluminum wheel. It is a manufacturing method of a painted product including a process. The colored base layer can be formed by the same method as described in the colored base layer forming method.

  The method for producing a coated product according to the present invention includes a top clear coating applied to the surface of the powder primer layer and the colored base layer coated on the aluminum wheel with the thermosetting powder coating for a wheel according to the present invention. A method for manufacturing a coated product including a step of forming a clear layer. The top clear layer can be formed by the same method as described in the method for forming the top clear layer.

  The coated product of the present invention is a coated product of an aluminum wheel manufactured by the above-described method for manufacturing a coated product. The coated product is a coated product in which an aluminum wheel, a powder primer layer, and, if necessary, a colored base layer and a top clear layer are laminated.

The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. Both parts and% are based on weight.

[Production Example 1 of hydroxyl group-containing polymer]
Into a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and dropping device, 60 parts of toluene was charged and heated to 105 ° C. while blowing nitrogen gas. 30 parts of styrene, 35 parts of methyl methacrylate, iso -A mixed liquid of 10 parts of butyl methacrylate, 25 parts of 2-hydroxyethyl methacrylate and 4 parts of azobisisobutyronitrile was added dropwise over about 3 hours. After the completion of dropping, the mixture was allowed to stand at 105 ° C. for 1 hour. Further, 0.5 part of azobisisobutyronitrile and 10 parts of toluene were dropped over 1 hour, and after the completion of dropping, the mixture was allowed to stand at 105 ° C. for 1 hour. finished. Then, pressure reduction operation was performed, the solvent in a system was removed, and the hydroxyl-containing polymer was obtained. The softening temperature of the polymer was 54 ° C., and the number average molecular weight was 3,500.

[Production Example 2 of Phosphate Ester Compound (a)]
To 115 parts of 85% phosphoric acid, 280 parts of butyl glycidyl ether was added and reacted at 50 to 60 ° C. for 3 hours to obtain a phosphate ester compound having an acid value of 142 mgKOH / g.

[Production Example 3 of Epoxy Compound (b)]
190 parts of Adeka Resin EP-4100 (Asahi Denka Kogyo Co., Ltd., trade name, bisphenol A type epoxy resin, epoxy equivalent 190), 58 parts of bisphenol A and 1 part of dimethylbenzylamine were mixed, reacted at 150 ° C. for 8 hours, and epoxy equivalent 500 epoxy compounds were obtained.

[Production Example 4 of Phosphate Modified Epoxy Resin]
115 parts of xylene and 20 parts of the phosphoric acid ester compound obtained in Production Example 2 were added to the epoxy compound obtained in Production Example 3 and reacted at 80 ° C. for 5 hours to allow xylene to flow out of the reaction vessel. Then, it cooled and the phosphoric acid modified epoxy resin was obtained.

[Production Example of Powder Primer Composition 1]
Carboxyl group-containing thermosetting polyester resin (Dainippon Ink & Chemicals, trade name, Finedick M-8860, softening point 113 ° C., acid value 35 mgKOH / g) 65 parts, epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., Trade name, Epicoat 1002, Epoxy equivalent 650, Softening point 78 ° C., Molecular weight 1060) 25 parts, 10 parts of phosphoric acid-modified epoxy resin obtained in Production Example 4 and 5 hydroxyl group-containing polymer obtained in Production Example 1 Next, mix 30 parts of JR-603 (trade name, titanium dioxide, manufactured by Teika Co., Ltd.), mix with a mixer, melt and knead with an extruder, finely pulverize with an atomizer after cooling, 150 mesh screen Was used to obtain a powder primer composition 1.

[Production Examples of Powder Primer Compositions 2-9]
Powder primer compositions 2 to 9 were obtained with the coating components shown in Table 1 by the same production method as that for powder primer composition 1.
Table 1

In Table 1, Epicoat 1004 is made by Japan Epoxy Resin Co., Ltd., trade name, epoxy equivalent 900, softening point 97 ° C.

Example 1
After alkaline degreasing, the film is coated with powder primer composition 1 on an aluminum alloy AC4C plate that has been subjected to chemical conversion treatment with chromate chromate (AL-1000: manufactured by Nihon Parker Rising Co., Ltd.). Electrostatic coating was performed to 100 μm, and heat curing was performed at 160 ° C. for 30 minutes. Spray coating is applied to the resulting powder primer coating film so that the coating thickness is 35 μm in black paint color paint (i.e., top coat) (trade name, Neo-Amilak US-300 No. 202, manufactured by Kansai Paint Co., Ltd.). And cured by heating at 140 ° C. for 30 minutes.

Example 2
On the aluminum alloy AC4C plate subjected to the same treatment as in Example 1, the powder primer composition 2 was electrostatically coated so as to have a film thickness of 100 μm and cured by heating at 160 ° C. for 30 minutes.
On the obtained powder primer coating film, a silver-painted design paint A containing a glittering pigment (aluminum pigment) is spray-coated so as to have a film thickness of 15 μm, and then heated and cured without being heated. The solvent-type acrylic clear paint a was spray-coated so that the film thickness was 35 μm, and was cured by heating at 140 ° C. for 30 minutes.

Examples 3-7
On the aluminum alloy AC4C plate subjected to the same treatment as in Example 1, the powder primer composition shown in Table 2 was electrostatically coated so as to have a film thickness of 100 μm, and was cured by heating at 160 ° C. for 30 minutes. . On top of that, a design paint and an acrylic clear paint as shown in Table 2 were applied as a top coat to prepare a coated plate. In addition, Table 2 shows the coating method film thickness and heat curing conditions of each top coat.
Table 2

Comparative Example 1
On the aluminum alloy AC4C plate subjected to the same treatment as in Example 1, the powder primer composition 5 was electrostatically coated so as to have a film thickness of 100 μm and cured by heating at 160 ° C. for 30 minutes. On the obtained powder primer coating film, a silver-painted design paint A containing a glittering pigment (aluminum pigment) is spray-coated so as to have a film thickness of 15 μm, and then heated and cured without being heated. The solvent-type acrylic clear paint a was spray-coated so that the film thickness was 35 μm, and was cured by heating at 140 ° C. for 30 minutes.
Comparative Examples 2-5
On the aluminum alloy AC4C plate subjected to the same treatment as in Example 1, the powder primer composition shown in Table 3 was electrostatically coated so as to have a film thickness of 100 μm, and was cured by heating at 160 ° C. for 30 minutes. . On top of that, a design paint and an acrylic clear paint as shown in Table 3 were applied as a top coat to produce a coated plate. In addition, Table 3 shows the coating method, film thickness, and heat curing conditions of each top coat.

  Table 3

  * 1) to * 8) in Tables 2 and 3 are as follows.

* 1) Designable paint A: manufactured by Kansai Paint Co., Ltd., trade name, acrylic solvent-based paint, AL2500 11SV14
* 2) Design paint B: manufactured by Kansai Paint Co., Ltd., trade name, water-based acrylic paint, WBC-710T NO. 199-1
* 3) Design paint C: manufactured by Kansai Paint Co., Ltd., trade name, two-component acrylic solvent paint, letan PG2K Sun Metallic
* 4) Acrylic clear paint a: manufactured by Kansai Paint Co., Ltd., trade name, solvent-type paint ALC-100
* 5) Acrylic clear paint b: manufactured by Kansai Paint Co., Ltd., trade name, solvent paint MAJIKRON KINO1200T
* 6) Acrylic clear paint c: Product name, Kansai Paint Co., Ltd., trade name, 2-pack type hydroxyl group-containing acrylic-polyisocyanate curing paint Super Diamond Clear Q
* 7) Acrylic clear paint d: manufactured by Kansai Paint Co., Ltd., trade name, epoxy group-containing acrylic-dodecanedicarboxylic acid-cured powder paint EVA Clad NO. 5600DK
* 8) UV curable clear paint e: 96 parts UV curable epoxy acrylate resin (trade name, Hitaroid 7851, manufactured by Hitachi Chemical Co., Ltd.), photopolymerization initiator (Daiichi Kogyo Seiyaku Co., Ltd., BDK: benzyldimethyl) Ketal, product name) 3 parts, BYK306 (manufactured by Big Chemie, product name) 1 part stirred with a disper.

  Tests were performed on the coating films of Examples and Comparative Examples. The results are shown in Table 4.

  Table 4

In Table 4, the test was conducted by the following method.
Finished appearance: The coating film appearance of the test plate coated up to the top coat was visually evaluated according to the following criteria.

○: Both smoothness and gloss are good. △: Smoothness and gloss are slightly bad. ×: Smoothness and gloss are bad.
Contamination: With respect to 100 parts of the powder primer, the above EVA cladding NO. After 0.1 parts of 5600 DK was dry blended, the finished appearance after paint baking was visually evaluated. Visual evaluation was performed according to the following criteria.
○: No cissing, △: Slight cissing occurred, ×: cissing occurred on the entire surface.
Corrosion protection: A cross-cut was performed so that a part of the test plate reached the substrate, and a salt spray test (JIS K5400-9) was performed for 1000 hours. After the test, washing and drying were performed, and the peel width and rust width of the coating film after the cellophane tape was applied to the state of the general part and the cross cut part and peeled were examined and evaluated according to the following criteria.

General part: ○: No abnormality, △: Spot rust and blisters occur in part, × Spot rust and blisters occur on the entire surface.
Peel width of cut part, rust width ... ◎: Within 0.5mm, ○: Within 1mm, △ 3-5mm, ×: 10mm or more
Chipping resistance: A test plate was placed on a test piece holder of a QGR GRaverometer (Q-PANEL, USA, chipping test device), and the particle size was reduced by compressed air of 4 kg / cm2 at -20 ° C. No. 7 granite crushed stone was sprayed, the state of scratches on the coating film was examined, and evaluated according to the following criteria.

○: The diameter of the scratch is 1 mm or less and the number of scratches is small. (Triangle | delta): The diameter of a damage | wound is 1.5-2.5 mm, and the number of a damage | wound is a little large. X: The diameter of a crack is 3 mm or more, and there are many scratches.
Water resistance: Immerse the test plate in warm water at 40 ° C, pull it up after 240 hours, observe the presence of abnormalities in blistering, glossiness and other coating surface, conduct cross-cut adhesion test, and evaluate it according to the following criteria .

  ○: There is no abnormality in the coating surface state, and there is no abnormality in adhesion. Δ: Swelling and luster are generated, but adhesion is not abnormal. X: Peeling occurs in the adhesion test.

The wheel thermosetting powder coating of the present invention has a strong resistance to contamination by different types of powder coatings, and has excellent wettability with respect to the top coating, resulting in extremely excellent finish, anticorrosion and chipping resistance. It can be used for excellent aluminum wheel painted articles.

Claims (8)

Carboxyl group-containing thermosetting polyester resin (A), epoxy resin not modified with phosphoric acid (B), hydroxyl group-containing acrylic resin (C) having a number average molecular weight of 1,000 to 10,000, and a monoglycidyl ether compound, A phosphate ester compound (a) having at least one P-OH bond obtained by reacting a monoglycidyl ester compound and phosphoric acid, and an epoxy compound (b) having one or more epoxy groups in the molecule A thermosetting powder coating material for aluminum wheels characterized by containing a phosphoric acid-modified epoxy resin (D) obtained by reacting, wherein the total amount of components (A) and (B) is 100 parts by weight The blending ratio of the hydroxyl group-containing polymer (C) is 0.1 to 20 parts by weight, and the blending ratio of the phosphoric acid-modified epoxy resin (D) is 0.5 to 30 parts by weight. A thermosetting powder coating material for aluminum wheels, characterized by being a part. A method for forming a coating film, comprising forming a powder primer layer by electrostatically coating an aluminum wheel with the thermosetting powder coating material for a wheel according to claim 1. The method for forming a coating film according to claim 2 , wherein a colored base coating film layer is formed on the surface of the primer layer. The method for forming a coating film according to claim 3, wherein a top clear layer is formed on the surface of the colored base layer. A method for producing a product coated with a powder coating, comprising the step of forming a powder primer layer by electrostatically coating the aluminum wheel with the thermosetting powder coating for a wheel according to claim 1. A method for producing a coated product, comprising: The manufacturing method of Claim 5 including the process of forming a coloring base coating-film layer in the said primer layer surface. The manufacturing method of Claim 6 including the process of forming a top clear layer in the said colored base layer surface. A coated product produced by the method according to any one of claims 5 to 7.