JP2011212568A - Coating film forming method and hydrophilic treatment agent solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating film forming method, which is excellent in contamination resistance of a portion in which the surface is polished and in which the contamination resistance continues for long periods.SOLUTION: The coating film forming method comprises coating a hydrophilic coating film or a coating film in which a hydrophilizing is possible with a hydrophilic treatment agent solution containing a silicone compound (A) containing at least one kind of organic functional group selected from a mercapto group, an epoxy group, a (meta)acryloyl group, a vinyl group, a haloalkyl group, and an amino group, and an organic solvent (B).

Description

  The present invention relates to a coating film forming method using a hydrophilic treatment agent, and more particularly to a coating film forming method including a step of applying a hydrophilic treatment agent to a hydrophilic or hydrophilic coating film.

  Since a top coating for automobiles constitutes the outermost layer of a coating film for automobile body coating, it is required to have excellent coating film properties such as scratch resistance, acid resistance, weather resistance, and finish. In addition, there is an increasing demand for ease of removal of dirt, that is, contamination resistance when contaminants such as soot and dust adhere to the coating film.

  Patent Document 1 discloses an automotive top coating in which a specific silicone compound is blended with an acid-epoxy curable coating for the purpose of solving the problem relating to contamination resistance. In this technology, the organic functional group of the specific silicone compound reacts with the organic resin in the paint to form a chemical bond, forms a hydrogen bond with a polar structure, and interacts based on affinity. This contributes to the suppression of the detachment of the silicone compound from the coating film. And the coating film by this coating composition is easily hydrolyzed by the alkoxysilyl group of the specific silicone compound present in the vicinity of the coating film surface to generate a silanol group, and has a high hydrophilic property due to the silanol group. Therefore, it exhibits contamination resistance.

  However, this hydrolysis reaction is affected by the rainfall conditions, and if the amount of rainfall is small, it may take time to form a hydrophilic coating film. Also, until the surface becomes hydrophilic, there is a problem that if hydrophobic contaminants adhere, it is difficult to remove dirt only by rain.

  Further, in the automobile painting line, when dust, blisters, scratches or the like are found on the painted surface after the top coat, the sand and paper may be polished and finished in the process of removing the dust, blisters.

  Since the silicone compound-containing layer that exists in the vicinity of the coating film surface is scraped off at the portion where the coating film is polished, the hydrophilicity disappears and the stain resistance decreases. Therefore, when looking at the entire automobile paint film, parts with different hydrophilization levels occur depending on the presence or absence of the polished parts, and there is a significant difference in the level of contamination resistance. There is a problem that occurs.

  In Patent Document 2, a silicon compound or a hydrolysis condensate thereof (a), or a mixture of a component (a) and a catalyst capable of hydrolyzing a silicon compound and / or an organic solvent is applied to the top coating film. Disclosed is an antifouling treatment method for membranes. However, the hydrophilic coating film formed on the surface by this antifouling treatment method dissolves and disappears little by little due to rain or the like, and there is a problem that the effect of the hydrophilic coating film is lost.

JP-A-10-147743 JP 2000-256619 A

An object of the present invention is to provide a method for forming a coating film which is excellent in the stain resistance of the portion where the surface of the top coat film is polished and which has a long-lasting stain resistance.

  As a result of intensive studies, the present inventors have achieved the above object by applying a hydrophilic treatment agent solution containing a specific silicone compound to a hydrophilic or hydrophilizable coating film this time. As a result, the present invention has been completed.

  Thus, the present invention contains at least one organic functional group selected from a mercapto group, an epoxy group, a (meth) acryloyl group, a vinyl group, a haloalkyl group and an amino group in a hydrophilic or hydrophilizable coating film. The present invention provides a coating film forming method characterized by applying a hydrophilizing agent solution containing a silicone compound (A) and an organic solvent (B).

  In the coating film forming method of the present invention, since the hydrophilic treatment agent is also applied to the portion whose surface has been polished, the contamination resistance of this polished portion is also excellent, and the stain resistance is sustained for a long time. Moreover, since the coating film formed by the method of the present invention has a high crosslinking density, it also has basic performance such as weather resistance. Furthermore, the coating film formed by the method of the present invention, when exposed for a long period of time, the coating film of the hydrophilic treatment agent on the surface gradually dissolves and disappears in the rain, but the previously formed hydrophilicity or hydrophilization Since the hydrophilic treatment agent in the present invention is retained on the possible coating film to a sufficient extent to maintain the hydrophilicity through chemical bonds, hydrogen bonds, etc., the hydrophilicity can be continuously maintained. And exhibits excellent stain resistance.

  Hereinafter, the coating film forming method of the present invention (hereinafter sometimes referred to as “the present method”) will be described in more detail.

  The hydrophilizing agent solution used in the method of the present invention is a silicone compound containing at least one organic functional group selected from a mercapto group, an epoxy group, a (meth) acryloyl group, a vinyl group, a haloalkyl group and an amino group. (A) and the organic solvent (B) are contained.

Silicone compound (A) :
The silicone compound (A) is an alkoxysilane compound containing at least one organic functional group selected from a mercapto group, an epoxy group, a (meth) acryloyl group, a vinyl group, a haloalkyl group and an amino group (hereinafter referred to as “organic functional group”). And a compound obtained by hydrolyzing and condensing at least partially a mixture of alkoxysilane compounds containing at least one organic functional group-containing alkoxysilane compound.

  Especially as a silicone compound (A), what is obtained by carrying out the partial cohydrolysis condensation of the mixture of an organic functional group containing alkoxysilane compound and a tetraalkoxysilane compound can be used conveniently.

The organic functional group-containing alkoxysilane compound has at least one, preferably 2 or 3, alkoxy groups bonded to a silicon atom, and at least one, preferably one organic functional group. One alkyl group bonded to the silicon atom may be contained. As the alkoxy group, an alkoxy group having 1 to 6, preferably 1 to 4 carbon atoms is suitable. The organic functional group may be directly bonded to the silicon atom, or may be bonded to the silicon atom via a divalent hydrocarbon group having 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms, preferably an alkylene group or a phenylene group. It may be bonded. As such an organic functional group-containing alkoxysilane compound, those known per se can be used, and specific examples thereof include the following.

  Mercapto group-containing alkoxysilane compound: γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltributoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, β- Mercaptomethylphenylethyltrimethoxysilane, mercaptomethyltrimethoxysilane, 6-mercaptohexyltrimethoxysilane, 10-mercaptodecyltrimethoxysilane, and the like.

  Epoxy group-containing alkoxysilane compound: γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltributoxysilane, γ-glycidoxypropyltriisopropenoxysilane, γ -Glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethylmethyldiethoxysilane, 5,6-epoxyhexyltrimethoxysilane, 9,10-epoxydecyltrimethoxysilane etc.

  (Meth) acryloyloxy group-containing alkoxysilane compounds: γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltributoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacrylic Roxypropylmethyldiethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-acryloxymethyltrimethoxy Silane etc.

  Vinyl group-containing alkoxysilane compounds: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, 5-hexenyltrimethoxysilane, 9-decenyltrimethoxysilane, styryltrimethoxysilane and the like.

  Haloalkyl group-containing alkoxysilane compounds: γ-chloropropyltrimethoxysilane, γ-bromopropyltrimethoxysilane, trifluoropropyltrimethoxysilane, nonafluorohexyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltri Ethoxysilane, γ-aminopropyltributoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, and the like.

  Amino group-containing alkoxysilane compound: N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltriethoxysilane, N- (β-aminoethyl)- γ-aminopropyltributoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane and the like.

  These organic functional group-containing alkoxysilane compounds may be used alone or in combination of two or more.

Among these compounds, it is preferable to use a mercapto group-containing alkoxysilane compound or an epoxy group-containing alkoxysilane compound because of excellent coating performance such as stain resistance and weather resistance.

  The organic functional group in the alkoxysilane compound containing an organic functional group forms a chemical bond with a resin component in the paint by a chemical reaction, forms a hydrogen bond with a polar structure, or interacts based on affinity, etc. It functions to prevent detachment of the silicone compound from the coating film.

  Examples of the tetraalkoxysilane compound that can be used in combination with the organic functional group-containing alkoxysilane compound include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane. These compounds can be used alone or in combination of two or more. Among these, it is particularly preferable to use tetramethoxysilane and tetraethoxysilane because the alkoxysilane group easily hydrolyzes to form a silanol group and form a coating film excellent in stain resistance.

  The ratio of the tetraalkoxysilane compound to the organofunctional group-containing alkoxysilane compound when used in combination is not strictly limited and can be varied over a wide range. The tetraalkoxysilane compound is preferably used in an amount of 20 to 2,000 parts by weight, particularly 35 to 1,500 parts by weight, more particularly 50 to 1,000 parts by weight, based on parts by weight. When the blending ratio is less than 20 parts by weight, the hydrophilicity of the co-hydrolyzed condensate of the organofunctional group-containing alkoxysilane compound and the tetraalkoxysilane compound is lowered. Inferior and undesirable. Further, when the blending ratio exceeds 2,000 parts by weight, the affinity and reactivity between the silicone compound (A) and the resin component become poor, and the ability to fix the silicone compound (A) in the coating film is insufficient. It is not preferable because it tends to be detached from the coating film after hydrolysis.

  The silicone compound (A) preferably has an average degree of polymerization generally in the range of 3 to 100, in particular 5 to 80, more particularly 8 to 60. If the degree of polymerization of the silicone compound (A) is less than 3, it may volatilize, it may not be possible to impart sufficient hydrophilicity to the coating film surface, or it may be easily eluted from the coating film. Conversely, when the degree of polymerization of the silicone compound (A) exceeds 100, it may be difficult to form a uniform coating film.

  The silicone compound (A) is prepared according to a method known per se, for example, an alkoxy containing at least one organic functional group-containing alkoxysilane compound or organic functional group-containing alkoxysilane compound in the presence of a hydrolysis (condensation) catalyst. It can be produced by adding water to the silane compound and carrying out a hydrolysis condensation reaction.

  In the hydrolytic condensation, the degree of hydrolysis is, for example, that the average degree of polymerization is 0 when not hydrolyzed at all, and conversely when 100% hydrolyzed, the degree of polymerization is too high and gelation occurs. In the silicone compound (A) used in the present invention, the average degree of polymerization is generally in the range of 3 to 100, particularly 5 to 80, more particularly 8 to 60, as described above. It is preferable to adjust to.

As the hydrolysis condensation catalyst, various catalysts known per se can be used. Specific examples include, for example, organic acids such as acetic acid, butyric acid, maleic acid, citric acid; hydrochloric acid, nitric acid, phosphoric acid, Inorganic acids such as sulfuric acid; basic compounds such as triethylamine; organometallic salts such as tetrabutyl titanate and dibutyltin dilaurate; fluorine-containing compounds such as potassium fluoride and ammonium fluoride. Among these catalysts, fluorine-containing compounds are excellent in the function of promoting the condensation of silanol groups rich in reaction activity, and are therefore suitable for synthesizing compounds containing only a small amount of silanol groups. This is particularly preferable because stability is improved. The above catalysts may be used alone or in combination of two or more. The amount of the catalyst used is usually preferably within the range of 0.0001 to 1 mol% with respect to the organic functional group-containing alkoxysilane compound or the mixture of the organic functional group-containing alkoxysilane compound and the alkoxysilane compound.

  In carrying out the hydrolysis condensation reaction, an organic solvent can be used as necessary. Usable organic solvents include, for example, alcohols such as methanol, ethanol, isopropanol, and t-butanol; ketones such as acetone and methyl isobutyl ketone; ethers such as dibutyl ether; esters such as ethyl acetate; Aromatics and the like. In particular, methanol, ethanol, acetone and the like are preferable.

  The amount of water used for the hydrolytic condensation reaction can be determined by the desired degree of polymerization. If it is added excessively, the alkoxy group is destroyed, and eventually gelation occurs. In particular, when a fluorine-containing compound is used as the catalyst, the fluorine-containing compound has the ability to completely proceed with hydrolysis condensation, the degree of polymerization can be determined by the amount of water added, and an arbitrary molecular weight can be set. Therefore, it is preferable. That is, when preparing a target product having an average degree of polymerization M, (M-1) mol of water is used with respect to the total M mol of the alkoxy group in the organofunctional group-containing alkoxysilane compound and the alkoxysilane compound. Good. In the case of other catalysts, the amount needs to be slightly increased.

  The hydrolysis condensation reaction can be carried out at a temperature within the range of room temperature to 150 ° C. If the temperature is lower than room temperature, the progress of the reaction is slow, which is not practical.

Organic solvent (B) :
Examples of the organic solvent (B) include hydrocarbon solvents such as heptane, toluene, xylene, octane, mineral spirits; ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, and the like. Ester solvents; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol, isobutanol; n-butyl ether, dioxane, ethylene glycol Ether solvents such as monomethyl ether and ethylene glycol monoethyl ether; SWAZOL 310, SWAZOL 1000, SWAT Lumpur 1500 (trade name) and aromatic petroleum solvents such as. These organic solvents can be used alone or in combination of two or more.

  Of the above, hydrocarbon solvents are preferred from the viewpoints of solubility of the silicone compound (A) and coating unevenness at the time of applying the hydrophilic treatment solution. Of the hydrocarbon solvents, toluene and xylene are particularly preferable.

  The organic solvent (B) is generally used from the viewpoint of coating workability when the hydrophilic treatment solution is wipe-coated, for example (if the hydrophilic treatment solution is too wet and spreads on the coating surface, it becomes difficult to perform the painting work). It is preferable to have a surface tension of 27 dyne / cm or more, particularly 28 dyne / cm or more.

  The organic solvent (B) generally has a water solubility of 1.0 g / 100 g or less, particularly 0.1 g / 100 g or less, more particularly 0.05 / 100 g or less, from the viewpoint of coating unevenness when applying the hydrophilic treatment agent solution. It is preferable to have.

  The organic solvent (B) also preferably has a solubility parameter value (SP value) of generally 10.0 or less, particularly 9.0 or less, from the viewpoint of uneven coating during application of the hydrophilizing agent solution.

  The organic solvent (B) preferably has an evaporation rate within the range of generally 180 to 900, particularly 200 to 850, more particularly 220 to 800, from the viewpoint of coating workability and the like. Here, the evaporation rate is a value represented by the number of seconds required for 90% by mass of the total amount of the test sample solvent to volatilize. The test method is defined in, for example, ASTM D3359.

Hydrophilic treatment solution :
The hydrophilic treatment agent solution can be prepared by mixing the silicone compound (A) and the organic solvent (B).

  In the hydrophilizing agent solution, the concentration of the silicone compound (A) is generally 1 to 10% by mass, particularly 2 with respect to the total amount of the silicone compound (A) and the organic solvent (B) from the viewpoint of coating workability and the like. It is preferably in the range of ˜8% by mass, more particularly in the range of 3 to 7% by mass.

  The method for applying the hydrophilizing agent solution is not particularly limited, and examples thereof include spray coating, roll coater method, brush coating, dip coating, and wipe coating. Of these, wipe coating is preferable from the standpoint of easy application. Wipe coating can be performed, for example, by applying an appropriate amount of a hydrophilizing agent solution using a cloth such as flannel and wiping to form a uniform coating film.

  The coated film may be left to dry at room temperature, or may be dried by heating at a temperature of about 40 to about 100 ° C. for about 1 to 30 minutes.

  It is preferable that the coating film has a thickness in the range of usually about 0.01 to about 10 μm, particularly about 0.5 to about 1 μm in terms of dry film thickness. If the film thickness is less than 0.01 μm, the stain resistance may not be maintained over a long period. Conversely, if the film thickness exceeds 10 μm, the finished appearance may be deteriorated or cracks may occur. .

Hydrophilic or Hydrophilizable Coating Film In the present invention, the hydrophilic treatment solution is applied to a hydrophilic or hydrophilic coating film. The hydrophilic coating film means a coating film having a water contact angle of 40 ° or less, preferably 35 ° or less, and the hydrophilic coating film conforms to JIS K 5400 9.9. It means a coating film having a water contact angle of 40 ° or less, preferably 35 ° or less when an outdoor exposure test is conducted for 6 months. If the water contact angle on the coating surface is 40 ° or less, it is less contaminated than when it exceeds 40 °, and even if it is contaminated, the contamination can be easily removed only by water or rain. Excellent pollution.

  The hydrophilic or hydrophilic coating film is usually formed on an object to be coated. Examples of objects to be coated include automobiles, motorcycles and other vehicle bodies or parts thereof; cold-rolled steel sheets, galvanized steel sheets, zinc alloy-plated steel sheets, stainless steel sheets, tin-plated steel sheets, etc. that form these car bodies; aluminum plates, aluminum Metal substrates such as alloy plates; various plastic substrates; various glass substrates; various mirror members.

  Further, as the article to be coated, the metal surface of the vehicle body, parts, metal base material may be subjected to chemical conversion treatment such as phosphate treatment, chromate treatment, complex oxide treatment, An undercoating film and / or an intermediate coating film such as various electrodeposition paints may be formed on the vehicle body, metal base material, or the like.

  The hydrophilic or hydrophilizable coating film can be a coating film formed by a top coating that is usually applied as the uppermost layer of the article to be coated. The top coating is not particularly limited, and examples thereof include a colored top coating and a top clear coating.

  Since the top coating forms a hydrophilic or hydrophilizable coating film, it usually contains a component (such as a component having an alkoxysilyl group and / or a silanol group) that exhibits hydrophilicity. The component capable of developing hydrophilicity is preferably the silicone compound (A) described above for the hydrophilizing agent solution.

  As the top clear paint, metallic pigments (eg, flake aluminum powder, copper powder, nickel powder, stainless steel powder, colored mica powder, etc.) and other colored pigments are not blended in the paint, or a coating film is formed. May be formulated so as not to completely cover the substrate.

  As an example of the coating of the overcoat clear paint, for example, it is known per se that has been conventionally used in the field of automobiles on the surface of a coating on which an undercoat and / or an intermediate coat is formed. An example is one in which an organic solvent type or aqueous topcoat base paint is applied and then a top clear paint is applied.

  Examples of the above-described clear coating material include, for example, known clear coating materials that have been used in the field of automobile coating, such as melamine curable clear coating materials such as acrylic resin / melamine resin systems, and acrylic resin / polyisocyanate compound systems. And the like, which are obtained by adding a silicone compound (A) to a urethane curable clear paint, etc., such as a carboxyl group-containing polymer (C) and an epoxy group-containing acrylic. A coating composition containing the resin (D) and the silicone compound (A) (hereinafter may be referred to as “top coating clear coating 1”) can be mentioned.

  Thus, a preferred top coat clear paint 1 as a top coat clear paint for forming a hydrophilic or hydrophilizable coating film includes a carboxyl group-containing polymer (C), an epoxy group-containing acrylic resin (D), and a silicone compound (A). ).

Carboxyl group-containing polymer (C) :
The carboxyl group-containing polymer (C) includes a known carboxyl group-containing polymer, and the preferred carboxyl group-containing polymer (C) has, for example, a group obtained by half-esterifying an acid anhydride group. Examples thereof include a vinyl polymer (C-1) and a carboxyl group-containing polyester polymer (C-2).

Vinyl polymer (C-1) having a group obtained by half-esterifying an acid anhydride group :
The group formed by half-esterifying an acid anhydride group is a group consisting of a carboxyl group and a carboxylic acid ester group obtained by adding an aliphatic monoalcohol to an acid anhydride group and ring-opening (ie, half-esterifying). means. Hereinafter, this group may be simply referred to as a half ester group.

  The polymer (C-1) can be easily obtained, for example, by copolymerizing a vinyl monomer having a half ester group and other vinyl monomers by a conventional method. Moreover, it can obtain easily also by carrying out similarly copolymerization using the vinyl monomer which has an acid anhydride group instead of the vinyl monomer which has a ester group, and half-esterifying this acid anhydride group. Furthermore, instead of the vinyl monomer having a ester group, a vinyl monomer having a hydroxyl group is similarly copolymerized, and then the hydroxyl group can be half-esterified.

  The vinyl monomer having a half ester group is a compound obtained by half-esterifying an acid anhydride group of a vinyl monomer having an acid anhydride group, and obtained by adding an acid anhydride to a hydroxyl group-containing vinyl monomer by half-esterification. And the like.

  Specific examples of the compound obtained by half-esterifying an acid anhydride group of a vinyl monomer having an acid anhydride group include, for example, vinyl monomers having an acid anhydride group such as maleic anhydride and itaconic anhydride, and aliphatic groups. Examples include monoesterified products with monoalcohols.

  Specific examples of the compound obtained by half-esterifying an acid anhydride with a hydroxyl group-containing vinyl monomer include, for example, phthalic anhydride and hexahydrophthalic anhydride as the hydroxyl group-containing vinyl monomer exemplified below as other vinyl monomers. The compound etc. which are obtained by adding acid anhydrides, such as, by half esterification, can be mentioned.

  Half esterification can be performed before and after the copolymerization reaction as described above. Examples of the aliphatic monoalcohol used for the half esterification include low molecular weight monoalcohols such as methanol, ethanol, isopropanol, tert-butanol, isobutanol, ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether. . The half esterification reaction can be carried out according to a usual method, for example, at a temperature of room temperature to about 80 ° C., if necessary, in the presence of a basic catalyst such as a tertiary amine.

  Examples of the other vinyl monomers include hydroxyl group-containing vinyl monomers; (meth) acrylic acid esters; vinyl ethers and allyl ethers; olefinic compounds and diene compounds; nitrogen-containing unsaturated monomers; vinyl aromatic compounds, for example, Examples thereof include styrene, α-methylstyrene, and vinyl toluene.

  Examples of the hydroxyl group-containing vinyl monomer include hydroxy having 2 to 8 carbon atoms of (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. Alkyl ester; monoester of polyether polyol such as polyethylene glycol, polypropylene glycol, polybutylene glycol and the like and unsaturated carboxylic acid such as (meth) acrylic acid; polyether polyol such as polyethylene glycol, polypropylene glycol, polybutylene glycol and the like 2 A monoether with a hydroxyl group-containing unsaturated monomer such as hydroxyethyl (meth) acrylate; an acid anhydride group-containing unsaturated compound such as maleic anhydride or itaconic anhydride, ethylene glycol, A diesterified product with glycols such as hexanediol and neopentyl glycol; hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether; allyl alcohol; 2-hydroxypropyl (meth) acrylate; α, β-unsaturated carboxylic acid; Additives with monoepoxy compounds such as “Cardura E10” (trade name, manufactured by Shell Petrochemical Co., Ltd.) and α-olefin epoxides; glycidyl (meth) acrylate, acetic acid, propionic acid, p-tert-butylbenzoic acid And adducts of monobasic acids such as fatty acids; adducts of the above hydroxyl group-containing monomers and lactones (for example, ε-caprolactone, γ-valerolactone), and the like.

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

Examples of (meth) acrylic acid esters include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, hexyl acrylate, and acrylic acid 2 -Ethylhexyl, n-octyl acrylate, decyl acrylate, stearyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, methacryl Isobutyl acid, tert-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, stearyl methacrylate C1-C24 alkyl ester or cycloalkyl ester of acrylic acid or methacrylic acid; methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, ethoxybutyl methacrylate, etc. And C2-C18 alkoxyalkyl esters of acrylic acid or methacrylic acid.

  Examples of the vinyl ether and allyl ether include linear or branched alkyl vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, butyl vinyl ether, tert-butyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether, octyl vinyl ether; Examples thereof include cycloalkyl vinyl ethers such as vinyl ether and cyclohexyl vinyl ether; allyl vinyl ethers such as phenyl vinyl ether and trivinyl ether; aralkyl vinyl ethers such as benzyl vinyl ether and phenethyl vinyl ether; and allyl ethers such as allyl glycidyl ether and allyl ethyl ether.

  Examples of the olefinic compound and diene compound include ethylene, propylene, butylene, vinyl chloride, butadiene, isoprene, chloroprene and the like.

  Examples of the nitrogen-containing unsaturated monomer include nitrogen-containing compounds such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and N-tert-butylaminoethyl (meth) acrylate. Alkyl (meth) acrylate; acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N , N-dimethylaminoethyl (meth) acrylamide and other polymerizable amides; 2-vinylpyridine, 1-vinyl-2-pyrrolidone, 4-vinylpyridine and other aromatic nitrogen-containing monomers; acrylonitrile, methacrylonitrile and other polymers Nitriles such as allylamine .

  The copolymerization of the above various monomer mixtures can be carried out using a general vinyl monomer polymerization method, but a solution type radical polymerization method in an organic solvent is preferred in consideration of versatility and cost. According to the solution-type radical polymerization method, the desired copolymer can be easily obtained by conducting a copolymerization reaction of a monomer mixture in an organic solvent in the presence of a polymerization initiator at a temperature within a range of about 60 to about 165 ° C. A polymer can be obtained. Examples of the organic solvent include aromatic solvents such as xylene and toluene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ester solvents such as ethyl acetate, butyl acetate, isobutyl acetate and 3-methoxybutyl acetate; Examples include alcohol solvents such as butanol and isopropyl alcohol. Examples of the polymerization initiator include azobisisobutyronitrile and benzoyl peroxide.

The copolymerization ratio of the vinyl monomer having a half ester group or an acid anhydride group and the other vinyl monomer is usually appropriately set to the following ratio based on the total mass of all monomers. That is, the vinyl monomer having a half ester group or an acid anhydride group is generally 5 to 40% by mass, particularly 7.5 to 35% by mass, from the viewpoint of the balance between curing reactivity and storage stability of the resulting copolymer. %, More particularly in the range of 10 to 30% by weight. Further, the other vinyl monomer is generally preferably in the range of 60 to 95% by mass, particularly 65 to 92.5% by mass, and more particularly 70 to 90% by mass. In addition, when using the vinyl monomer which has an acid anhydride group, a half-esterification reaction is performed as mentioned above after a copolymerization reaction.

  In addition, the polymer (C-1) is compatible with the epoxy group-containing acrylic resin (D) and the silicone compound (A), from the viewpoint of excellent gloss, acid resistance, and the like of the coating film of the resulting coating composition. A number average molecular weight generally within the range of about 1,000 to about 10,000, especially about 1,100 to about 8,500, more particularly about 1,200 to about 7,000 and generally about 50 to 250 mg KOH / g, Particularly preferred is an acrylic polymer having an acid value in the range of 75 to 225 mgKOH / g, more particularly 100 to 200 mgKOH / g.

In the present specification, the number average molecular weight of the resin is measured by GPC (gel permeation chromatograph) with reference to standard polystyrene. The measurement of the number average molecular weight in the below-mentioned production examples etc. is carried out by using “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) as a GPC device, “TSKgel G-4000HXL”, “TSKgel”
G-3000HXL ”,“ TSKgel G-2500HXL ”and“ TSKgel G-2000HXL ”(both manufactured by Tosoh Corporation, trade name), mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: The measurement was performed under the conditions of 1 cc / min and detector: RI.

Carboxyl group-containing polyester polymer (C-2) :
The carboxyl group-containing polyester polymer (C-2) can usually be easily obtained by a condensation reaction between a polyhydric alcohol and a polyvalent carboxylic acid. For example, a carboxyl group-containing polyester polymer can be obtained by a one-step reaction under blending conditions in which the carboxyl group of the polyvalent carboxylic acid becomes excessive. Conversely, after synthesizing a hydroxyl-terminated polyester polymer under compounding conditions in which the hydroxyl group of the polyhydric alcohol is excessive, the carboxyl group-containing polyester polymer can also be obtained by post-adding an acid anhydride group-containing compound. Obtainable.

  Examples of the polyhydric alcohol include ethylene glycol, butylene glycol, 1,6-hexanediol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and trimethylol. Examples thereof include propane and pentaerythritol. Examples of the polyvalent carboxylic acid include adipic acid, terephthalic acid, isophthalic acid, phthalic anhydride, hexahydrophthalic anhydride, and the like. Examples of the acid anhydride group-containing compound include phthalic anhydride, hexahydrophthalic anhydride, succinic anhydride, and the like.

  The molecular weight of the carboxyl group-containing polyester polymer (C-2) is not particularly limited, but the coating film formed from the coating composition containing the polymer is usually about from the viewpoint of excellent gloss, acid resistance and the like. It is preferred to have a number average molecular weight in the range of 500 to about 10,000, especially about 650 to about 7,500, more particularly about 800 to about 5,000.

Further, the carboxyl group-containing polyester polymer (C-2) is improved in compatibility with the epoxy group-containing acrylic resin (D) and the silicone compound (A), and the adhesion of the coating film of the coating composition containing the same. For the purpose of improving the properties, the hydroxyl group can be introduced in such an amount that the hydroxyl value of the polymer is about 100 mgKOH / g or less, preferably about 10 to about 100 mgKOH / g. The introduction of a hydroxyl group can be carried out, for example, by stopping the condensation reaction in the middle of the above-mentioned compounding condition with excess carboxyl group, and conversely, in the compounding condition with excess hydroxyl group, the hydroxyl group-terminated polyester polymer. Can be easily carried out by blending the acid anhydride group-containing compound to be added later so that the acid groups are less than the hydroxyl groups.

  Among the carboxyl group-containing polyester polymers (C-2), particularly preferred are the carboxyl group-containing high acid value polyesters described below. Here, the high acid value polymer usually means a polymer having an acid value exceeding 70 mgKOH / g.

  A carboxyl group-containing high acid value polyester, for example, performs an esterification reaction between a polyhydric alcohol and a polyvalent carboxylic acid or a lower alkyl esterified product thereof under a blending condition in which the amount of hydroxyl groups is relatively excessive from the amount of carboxyl groups. To obtain a polyester polyol, and then this polyester polyol can be easily obtained by a half-esterification reaction with an acid anhydride group-containing compound. Here, the carboxyl group includes an acid anhydride group, and 1 mol of the acid anhydride group is 2 mol of the carboxyl group, and the amount of the carboxyl group is calculated. The esterification reaction may be either a condensation reaction or a transesterification reaction.

  The polyester polyol can be obtained by ordinary esterification reaction conditions. The polyester polyol generally has a number average molecular weight in the range of about 350 to about 4,700, especially about 400 to about 3,000, and generally in the range of about 70 to about 400 mg KOH / g, especially about 150 to about 350 mg KOH / g. It preferably has a hydroxyl value of This half-esterification reaction of the polyester polyol can be performed according to a usual method, for example, at a temperature of room temperature to about 80 ° C., if necessary, in the presence of a basic catalyst such as a tertiary amine.

  Examples of the polyhydric alcohol include ethylene glycol, butylene glycol, 1,6-hexanediol, trimethylolpropane, and pentaerythritol. Examples of the polyvalent carboxylic acid include adipic acid, sebacic acid, Examples include terephthalic acid, isophthalic acid, phthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, and the like. Examples of the acid anhydride group-containing compound include phthalic anhydride, hexahydrophthalic anhydride, succinic anhydride, trimellitic anhydride, and the like.

  The carboxyl group-containing high acid value polyesters generally have a number average molecular weight in the range of about 800 to about 5,000, especially about 850 to about 4,500, more particularly about 900 to about 4,000, and generally about 50 to about 4,000. It is preferred to have an acid number in the range of 300 mg KOH / g, especially about 75 to about 275 mg KOH / g, more particularly about 100 to about 250 mg KOH / g.

Epoxy group-containing acrylic resin (D) :
The epoxy group-containing acrylic resin (D) functions as a crosslinking curing agent for the carboxyl group-containing polymer (C).

  The epoxy group-containing acrylic resin (D) may contain an alkoxysilyl group in addition to the epoxy group. By including an alkoxysilyl group, the cross-linking density of the coating film formed from the composition containing the acrylic resin (D) is increased, and the scratch resistance and stain resistance of the coating film are further improved. Is obtained.

  The acrylic resin (D) is synthesized, for example, by copolymerizing an epoxy group-containing vinyl monomer and other vinyl monomers, or an epoxy group-containing vinyl monomer, an alkoxysilyl group-containing vinyl monomer, and other vinyl monomers. be able to.

Examples of the vinyl monomer having an epoxy group include glycidyl (meth) acrylate, allyl glycidyl ether, 3,4-epoxycyclohexylmethyl (meth) acrylate, and the like.

  Examples of vinyl monomers having an alkoxysilyl group include vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltris (2-methoxyethoxy) silane, and γ- (meth) acryloyloxypropyl. Trimethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, vinyltriacetoxysilane, β- (meth) acryloyloxyethyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, γ- (meth) Examples include acryloyloxypropylmethyldiethoxysilane. Among these, from the viewpoint of excellent low-temperature curability and storage stability, vinyltriethoxysilane, vinylmethyldiethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, where the alkoxysilyl group is an ethoxysilyl group, γ- (Meth) acryloyloxypropylmethyldiethoxysilane and the like are preferable.

  As other vinyl monomers, those exemplified in the production of the polymer (C-1) can be used in the same manner.

  The epoxy group-containing acrylic resin (D) can be produced using the same method as the copolymerization method described above for the production of the polymer (C-1).

  Epoxy group-containing acrylic resin (D) improves compatibility with carboxyl group-containing polymer (C) and silicone compound (A), and adheres to a coating film formed from a coating composition containing the resin (D) For the purpose of improving the properties, the hydroxyl group can be introduced in an amount such that the hydroxyl value of the resin is about 150 mgKOH / g or less, preferably about 10 to about 150 mgKOH / g.

  The introduction of a hydroxyl group can be carried out by copolymerization using a hydroxyl group-containing vinyl monomer as a comonomer component. As a hydroxyl-containing vinyl monomer, the thing similar to what was illustrated in the case of manufacture of a polymer (C-1) can be used.

  When copolymerizing a vinyl monomer having an epoxy group and other vinyl monomers, the epoxy group-containing vinyl monomer is the total mass of all monomers from the viewpoint of the balance between curing reactivity and storage stability of the copolymer obtained. In general, it is preferably used in the range of 5 to 80% by mass, particularly 10 to 65% by mass. The other vinyl monomer is preferably used in a range of generally 20 to 95% by mass, particularly 35 to 90% by mass, based on the total mass of all monomers.

  When a vinyl monomer having an epoxy group, a vinyl monomer having an alkoxysilyl group, and other vinyl monomers are copolymerized, the following copolymerization ratio is preferable based on the total mass of all monomers. The vinyl monomer having an epoxy group is generally preferably in the range of 5 to 60% by mass, particularly 10 to 40% by mass, from the viewpoint of the balance between the curing reactivity and storage stability of the copolymer obtained. The vinyl monomer having an alkoxysilyl group is generally 3 to 40 masses from the viewpoint of excellent curing reactivity of the resulting copolymer and excellent scratch resistance of a coating film formed from the composition containing the copolymer. %, Particularly within the range of 5 to 30% by mass. Further, the other vinyl monomer is generally preferably in the range of 10 to 80% by mass, particularly 20 to 50% by mass.

The epoxy group content of the acrylic resin (D) is compatible with the carboxyl group-containing polymer (C) and the silicone compound (A), curability when used as a coating composition, acid resistance of the resulting coating film, From the viewpoint of excellent scratch resistance and the like, it is generally 0.5 to 5.5 mmol / g, particularly preferably 0.00.
It is preferably within the range of 8 to 4.5 mmol / g.

  When the acrylic resin (D) has an alkoxysilyl group, its content is generally 0 from the viewpoint of excellent storage stability when used as a coating composition and acid resistance, scratch resistance, etc. of the formed coating film. It is preferable to be in the range of 0.05 to 2.5 mmol / g, particularly 0.15 to 1.75 mmol / g.

  The acrylic resin (D) is generally 1,000 from the viewpoints of compatibility with the carboxyl group-containing polymer (C) and the silicone compound (A) and excellent acid resistance and scratch resistance of the formed coating film. It is preferred to have a number average molecular weight in the range of ˜10,000, in particular 1,100 to 8,500, more particularly 1,200 to 7,000.

  From the viewpoint of curability, the blending ratio of the carboxyl group-containing polymer (C) and the epoxy group-containing acrylic resin (D) has an equivalent ratio of the carboxyl group in the component (C) to the epoxy group in the component (D). In general, the ratio is preferably in the range of 1: 0.5 to 0.5: 1, particularly 1: 0.6 to 0.6: 1.

Silicone compound (A) :
As a silicone compound (A), what was illustrated about the said hydrophilization treatment agent solution can be used similarly.

  As the silicone compound (A), those obtained by partially cohydrolyzing and condensing a mixture of an organic functional group-containing alkoxysilane compound and a tetraalkoxysilane compound, as in the case of the hydrophilic treatment solution, are particularly preferably used. Can do.

  Among the above, since the coating film performance such as stain resistance and weather resistance and the compatibility with the carboxyl group-containing polymer (C) and the epoxy group-containing acrylic resin (D) are excellent, the mercapto group-containing alkoxysilane compound and / or Alternatively, a silicone compound obtained by using an epoxy group-containing alkoxysilane compound as an organic functional group-containing alkoxysilane compound is preferable.

  Moreover, the silicone compound obtained using tetramethoxysilane and tetraethoxysilane as a tetraalkoxysilane compound from a viewpoint that the coating film excellent in stain resistance can be formed among the above is preferable.

  Furthermore, from the viewpoint of coating properties such as stain resistance and stain resistance maintenance and acid resistance, the tetraalkoxysilane compound is added in an amount of 20 to 2,000 with respect to 100 parts by weight of the alkoxysilane compound containing an organic functional group. A silicone compound obtained by partial cohydrolysis condensation by use within a range of parts by weight, particularly 35 to 1,500 parts by weight, more particularly 50 to 1,000 parts by weight, can be suitably used.

  The silicone compound (A) is excellent in compatibility with the carboxyl group-containing polymer (C) and the epoxy group-containing acrylic resin (D), and excellent in coating film performance such as stain resistance and weather resistance of the formed coating film. In general, it is preferable to have a number average molecular weight in the range of 500 to 5000, particularly 750 to 4000, more preferably 1000 to 3000.

From the viewpoint that the blending ratio of the carboxyl group-containing polymer (C), the epoxy group-containing acrylic resin (D) and the silicone compound (A) in the top clear coating 1 is excellent in the stain resistance, weather resistance, hardness, etc. of the coating film. The component (C) is generally 20 to 80 parts by weight, preferably 30 to 75 parts by weight, more preferably 35 to 65 parts by weight, based on 100 parts by weight of the total solid content of the components (C) and (D). In the range of parts, the component (D) is generally 80 to 20 parts by weight, preferably 70 to 25 parts by weight, more preferably 65 to 35 parts by weight, and the component (A) is generally 1 to 20 parts by weight. Parts, preferably 2 to 17.5 parts by mass, more preferably 3 to 15 parts by mass.

Other ingredients :
A curing catalyst can be blended in the top clear paint 1 as necessary. As a curing catalyst, as an effective catalyst for a crosslinking reaction between a carboxyl group and an epoxy group, for example, tetraethylammonium bromide, tetrabutylammonium bromide, tetraethylammonium chloride, tetrabutylphosphonium bromide, triphenylbenzylphosphonium chloride, etc. And quaternary salt catalysts; amines such as triethylamine and tributylamine. Of these, quaternary salt catalysts are preferred. Furthermore, when the quaternary salt is mixed with a phosphoric acid compound such as monobutyl phosphoric acid or dibutyl phosphoric acid that is approximately equivalent to the quaternary salt, the storage stability of the paint is improved without impairing the catalytic action, and the electrical properties of the paint This is preferable in that it can prevent a decrease in spray coating suitability due to a decrease in resistance value.

  In addition, the top clear paint 1 may be mixed with a dehydrating agent such as trimethyl orthoacetate in order to suppress deterioration of the paint due to moisture present in the paint or in the air, if necessary.

  If necessary, the top clear paint 1 can be blended with known pigments such as color pigments, extender pigments, glitter pigments and rust preventive pigments.

  Examples of the coloring pigment include titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chromium yellow, chromium oxide, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, selenium pigment, Examples of the extender pigment include talc, clay, kaolin, barita, barium sulfate, barium carbonate, calcium carbonate, silica, and alumina white. Examples of the glitter pigment include Examples thereof include aluminum powder, mica powder, and mica powder coated with titanium oxide.

  In addition to the carboxyl group-containing polymer (C) and epoxy group-containing acrylic resin (D), various resins such as an acrylic resin, a polyester resin, an alkyd resin, and a fluorine resin are added to the top clear coating 1 as necessary. It is also possible to do. Moreover, in order to improve curability, it is also possible to use together crosslinking agents, such as a melamine resin and a block polyisocyanate compound. Furthermore, it is also possible to mix | blend general paint additives, such as a ultraviolet absorber, a light stabilizer, antioxidant, a surface conditioner, and an antifoamer, as needed.

  As the ultraviolet absorber, those known per se can be used, and examples thereof include ultraviolet absorbers such as benzotriazole absorbers, triazine absorbers, salicylic acid derivative absorbers, and benzophenone absorbers. it can. By blending an ultraviolet absorber, the weather resistance, yellowing resistance and the like of the coating film can be improved.

  The content of the UV absorber is usually 0 to 10 parts by weight, preferably 0.2 to 5 parts by weight, more preferably 0.3 to 2 parts per 100 parts by weight of the total resin solid content in the paint. It can be in the range of parts by mass.

  As the light stabilizer, those known per se can be used, and examples thereof include hindered amine light stabilizers. By blending the light stabilizer, the weather resistance, yellowing resistance and the like of the coating film can be improved.

  The content of the light stabilizer is usually 0 to 10 parts by mass, 0.2 to 5 parts by mass, more preferably 0.3 to 2 parts by mass with respect to 100 parts by mass of the total amount of resin solids in the paint. Can be within the range.

  The form of the top clear paint 1 is not particularly limited, but it is usually preferable to use it as an organic solvent-type paint composition. Examples of the organic solvent used in this case include various organic solvents for paints, such as aromatic or aliphatic hydrocarbon solvents; alcohol solvents; ester solvents; ketone solvents; ether solvents. As the organic solvent to be used, those used at the preparation of the component (C), the component (D), the component (A) and the like may be used as they are, or may be appropriately added.

Preparation of top clear paint 1 :
The top clear coating 1 is composed of a carboxyl group-containing polymer (C), an epoxy group-containing acrylic resin (D), a silicate compound (A), and a curing catalyst, a pigment, various resins, an ultraviolet absorber, an optical agent used as necessary. Stabilizers, organic solvents and the like can be prepared by mixing them by a method known per se. The solid content concentration of the top clear coating 1 is generally 30 to 70% by mass, and particularly preferably 40 to 60% by mass.

When a top coat base paint and a top coat clear paint are used in combination, the top coat base paint is not particularly limited. For example, a paint comprising a film-forming resin, a curing agent, a pigment, and other additives. Can be used.

  The film-forming resin is not particularly limited, and examples thereof include acrylic resin, polyester resin, alkyd resin, epoxy resin, urethane resin, and the curing agent includes, for example, amino resin, block A polyisocyanate compound, a polycarboxylic acid compound, a silane compound, etc. can be mentioned.

  As said pigment, a coloring pigment, an extender pigment, and / or a luster pigment can be used individually or in combination of 2 or more types, respectively.

  Examples of the color pigment and extender pigment include those exemplified for the top clear paint 1, and these may be used alone or in combination of two or more.

  Examples of the glitter pigment include aluminum powder, copper powder, nickel powder, stainless steel powder, mica powder, interference mica powder, colored mica powder, alumina flake, graphite flake, and the like. In addition, two or more kinds may be used in combination.

  The solid content of the topcoat base paint can be usually 60% by mass or less, and the solid content at the time of application can be usually 10 to 50% by mass.

  As the additive that can be added to the topcoat base paint, those exemplified for the topcoat clear paint 1 can be used.

Method for Forming Coating Film According to the present invention, the hydrophilic treatment agent solution is applied to the hydrophilic or hydrophilic coating film formed as described above.

The hydrophilic or hydrophilizable coating is usually a coating formed by applying a top coating to the uppermost layer of the object to be coated as described above, and the colored top coating or top coating described above. Examples include clear paint.

  The method of the present invention may further include other steps as long as it includes the step of applying the hydrophilic treatment agent solution to a hydrophilic or hydrophilizable coating film.

  Examples of the coating process using the clear top coating include the following processes known per se in the field of automobiles.

  Step A: 2 coat 1 bake method (top coat base paint / top clear paint / baking), 2 coat 2 bake system (top coat base paint / baking / top coat clear paint / baking).

  Step B; 3-coat 1-bake method (top coat base paint / first overcoat clear paint / second overcoat clear paint / baking) 3-coat 2-bake system (top coat base paint / first overcoat clear paint / baked / second overcoat clear) Paint / baking) 3-coat 3-bake method (top coat base paint / baking / first top clear paint / baking / second top clear paint / baking).

  Step C; 3 coat 1 bake method (first top coat base paint / second top coat base paint / top clear paint / baking), 3 coat 2 bake system (first top coat base paint / second top coat base paint / baking / top coat clear) Paint / baking) 3 coat 3 bake system (first top coat base paint / baking / second top coat base paint / baking / top clear paint / baking).

  Further, from the viewpoint of saving the process, the following step D in which the intermediate coating film and the top coating film are cured together can be exemplified.

  Step D: 3-coat 1-bake method (intermediate paint / top coat base paint / top clear paint / baking).

  In Steps A to D, the intermediate coating material and the top coating material used may be either a solvent-based coating or a water-based coating.

  The top coat base paint and top coat clear paint can be applied by, for example, air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, or the like. In air spray coating, airless spray coating, and rotary atomization coating, electrostatic application may be applied as necessary. Of these, air spray coating and rotary atomization coating are particularly preferred.

  The wet coating is usually cured by heating (baking). Heating can be performed by a heating means known per se. For example, a drying furnace such as a hot air furnace, an electric furnace, or an infrared induction heating furnace can be applied.

  The curing temperature (baking temperature) can be generally in the range of about 100 to about 180 ° C, preferably about 120 to about 160 ° C. The curing time can be changed depending on the curing temperature or the like, but it is usually appropriate to be within a range of about 10 to 40 minutes at 120 to 160 ° C.

  The dry film thickness of the base coating film by the above-mentioned top coat base paint is generally about 5 to 40 μm, particularly about 10 to 30 μm. If the dry film thickness is less than 5 μm, the masking of the base may be insufficient, and if it exceeds 40 μm, problems may occur in the painting work such as wrapping and sagging.

The dry film thickness of the clear coating film by the above-described clear coating is generally about 10 to 80 μm, particularly about 15 to 60 μm. If the dry film thickness is less than 10 μm, the weather resistance of the coating film may be insufficient, and if it exceeds 60 μm, problems such as peeling and sagging may occur.

  In step A, an overcoating base paint is applied onto the article to be coated so that the cured film thickness is about 10 to 50 μm. The coated top coat is cured by heating at about 100 to about 180 ° C., preferably about 120 to about 160 ° C. for about 10 to about 40 minutes, or left at room temperature for several minutes without curing after coating or Preheat at about 40 to about 100 ° C. for about 1 to about 20 minutes.

  Next, a cured multi-layer coating film can be formed by applying and heating the clear coat paint so that the film thickness is about 10 to about 70 μm as a cured film thickness. The heating is preferably performed at about 100 to about 180 ° C., particularly about 120 to about 160 ° C. for about 10 to about 40 minutes.

  In the above step A, the case where the top coat base paint is applied and the top coat clear paint is applied without being heated and cured, and these two-layer coating films are simultaneously cured is a two-coat one-bake method. The 2-coat 2-bake method is used in which a clear coating is applied after coating and heat-curing (baking), and then the clear coating is cured.

  As the top coat base paint in Step B, the same top coat base paint as in Step A can be used. Further, the first top coat clear paint may be any paint for forming a transparent coating film, and for example, a paint that does not contain most or all of the pigment in the top coat base paint can be used. And as a 2nd topcoat clear coating material which forms the uppermost layer coating film, the clear coating material which can form the hydrophilicity or the hydrophilizable coating film, for example, the said top coating clear coating material 1, can be used.

  In step B, as in step A, a top coat base coating is applied on the object to be coated and heat-cured, or left to stand for several minutes at room temperature or pre-heated without being cured. A first overcoat clear coating is applied on the film so that the film thickness is about 10 to about 50 μm in cured film thickness, and about 100 to about 180 ° C., preferably about 120 to about 160 ° C., about 10 to about Heat for 40 minutes to cure or leave at room temperature for several minutes without curing or preheat.

  Next, a cured multi-layer coating film can be formed by applying and heating the second overcoat clear coating so that the film thickness is about 10 to about 50 μm in terms of the cured film thickness. The heating conditions can be the same as in step A.

  There is a case where the first base clear paint is applied without applying the top base paint and heat curing, the second top clear paint is applied without curing, and these three-layer coatings are simultaneously cured. Coat 1 bake method, without applying the top base paint and heating and curing, applying the first top clear paint, heating and curing these coatings at the same time, applying the second top clear paint and curing In the case of 3 coats and 2 bake method, the top coat base paint is applied and heat-cured, the first top clear paint is applied and cured, and the second top coat clear paint is applied and cured. The case is a 3 coat 3 bake system.

  In the step C, as the first topcoat base paint, the same topcoat base paint as that described above can be used.

In step C, the first top coat base paint is applied on the article to be coated and heat-cured in the same manner as in step A, or left to stand at room temperature for several minutes or pre-heated without being cured.
A second topcoat base paint is applied onto the topcoat base coating so that the film thickness is about 10 to about 50 μm in cured film thickness, and about 100 to about 180 ° C., preferably about 120 to about 160 ° C. Heat for 10 to about 40 minutes to cure or leave or preheat at room temperature for several minutes without curing.

  Next, a top clear coating that forms the uppermost layer coating is applied. As the top clear paint, a clear paint capable of forming a hydrophilic or hydrophilizable coating film, for example, the top clear paint 1 can be used.

  A cured multi-layer coating film can be formed by applying and heating the clear coat paint so that the film thickness is about 10 to about 50 μm as a cured film thickness. The heating conditions can be the same as in step A.

  There are 3 cases where the first topcoat base paint is applied and heated and cured, the second topcoat base paint is applied, the topcoat clear paint is applied without curing, and these three-layer coating films are simultaneously cured. This is a coat-one-bake method, and the first top coat base paint is applied and heat cured, the second top coat base paint is applied, the top clear paint is applied without curing, and the coating films are cured simultaneously. The case is a 3-coat 2-bake method, and the first top coat base paint is applied and heat cured, the second top coat base paint is applied, this is cured, the top clear paint is applied, and this is cured. Is a 3-coat 3-bake method.

  Hereinafter, the present invention will be described more specifically with reference to production examples, examples and comparative examples. These production examples, examples and comparative examples are merely illustrative and are not intended to limit the scope of the present invention. In the production examples, examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified. Moreover, the film thickness of a coating film is based on a cured coating film.

Production of silicone compound (A) Production example 1: Production of a silicone compound containing a mercapto functional group and an alkoxy group (Production example of silicone compound A1)
In a 1000 ml reaction vessel equipped with a thermometer, a nitrogen inlet tube and a dropping funnel, 196 parts (1 mole) of γ-mercaptopropyltrimethoxysilane, 152 parts (1 mole) of tetramethoxysilane, 320 parts (10 moles) of methanol and 0.06 part (0.001 mol) of potassium fluoride was charged, and 28.8 parts (1.6 mol) of water was slowly added dropwise at room temperature with stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 3 hours and then heated and stirred under methanol reflux for 2 hours. Thereafter, the low-boiling component was distilled off under reduced pressure and filtered to obtain 231 parts of a colorless transparent liquid.

  As a result of GPC measurement of this colorless and transparent liquid, the average degree of polymerization was 5.4 (set degree of polymerization 5.0), which was almost as set.

  When the amount of alkoxy groups was quantified by the alkali cracking method, it was 42.0% by mass (set value 42.9% by mass), and it was confirmed that the alkoxy groups remained as set.

Further, when the active hydrogen by the methyl Grignard reagent was quantified, it was 3.51 × 10 ⁻³ mol / g (mercapto group-derived active hydrogen amount (setting value): 3.64 × 10 ⁻³ mol / g), It was confirmed that the mercapto group was introduced almost as set.

  The silicone compound thus obtained is designated as silicone compound A1.

Production Example 2: Production of Epoxy Functional Group and Alkoxy Group-Containing Silicone Compound (Production Example of Silicone Compound A2)
In a 2000 ml reaction vessel equipped with a thermometer, a nitrogen inlet tube and a dropping funnel, 236 parts (1 mole) of γ-glycidoxypropyltrimethoxysilane, 152 parts (1 mole) of tetramethoxysilane, 320 g (10 moles) of methanol Then, 0.06 part (0.001 mol) of potassium fluoride was charged, and 28.8 parts (1.6 mol) of water was slowly added dropwise at room temperature with stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 3 hours and then heated and stirred under methanol reflux for 2 hours. Thereafter, the low-boiling component was distilled off under reduced pressure and filtered to obtain 266 parts of a colorless transparent liquid.

  As a result of GPC measurement of this colorless transparent liquid, the average degree of polymerization was 5.3 (set degree of polymerization 5.0), which was almost as set.

  When the amount of alkoxy groups was quantified by the alkali cracking method, it was 36.8% by mass (set value 37.4% by mass), and it was confirmed that the alkoxy groups remained as set.

  Moreover, when the epoxy equivalent was measured by the epoxy ring-opening method with hydrochloric acid, it was 319 g / mol (set value 314 g / mol), and it was confirmed that a predetermined amount of epoxy groups were introduced.

  The silicone compound thus obtained is designated as silicone compound A2.

Production example of hydrophilizing agent solution Example 1
5 parts of the silicone compound A1 produced in Production Example 1 (solid content: 100%) and 95 parts of toluene as an organic solvent were stirred and mixed uniformly to obtain a hydrophilizing agent solution 1 (mass solid content concentration; 5%).

Examples 2 to 9 and Comparative Example 1
In Example 1, hydrophilizing agent solutions 1 to 10 were obtained in the same manner as in Example 1 except that the silicone compound and the organic solvent were changed to the types and amounts shown in Table 1 below. The hydrophilic treatment solution 10 is a comparative example.

The MKC silicate MS51 in the table is a methyl silicate condensate (trade name, manufactured by Mitsubishi Chemical Corporation), and is selected from mercapto groups, epoxy groups, (meth) acryloyl groups, vinyl groups, haloalkyl groups, and amino groups. It is a silicone compound that does not contain at least one organic functional group.

  Table 2 below shows special values of the surface tension, water solubility, evaporation rate, and solubility parameter value (SP value) of each organic solvent in Table 1.

  In Table 2, the water solubility is the maximum amount that can be dissolved in 100 g of water at 20 ° C. The evaporation rate (90%) is a value measured by a test method specified in ASTM D3359, and is the time required for 90% of the total amount of solvent to evaporate. The smaller the value, the easier it is to evaporate.

Production of carboxyl group-containing polymer (C) Production Example 3
A four-necked flask equipped with a stirrer, thermometer, cooling pipe and nitrogen gas inlet is charged with 680 parts of “Swazol 1000” (trade name, hydrocarbon organic solvent, manufactured by Cosmo Oil Co., Ltd.), and nitrogen gas The temperature was raised to 125 ° C. under aeration. After reaching 125 ° C., the flow of nitrogen gas was stopped, and the following monomer mixture I composed of a monomer, a solvent and a polymerization initiator (p-tert-butylperoxy-2-ethylhexanoate) was added over 4 hours. And dripped.
Monomer mixture I
Styrene 500 parts Cyclohexyl methacrylate 400 parts Isobutyl methacrylate 500 parts Maleic anhydride 600 parts 2-Ethoxyethyl propionate 1,000 parts p-tert-butylperoxy-2-ethylhexanoate 100 parts

  Next, after aging for 30 minutes while bubbling nitrogen gas at 125 ° C., a mixture of 10 parts of p-tert-butylperoxy-2-ethylhexanoate and 80 parts of “Swazole 1000” was added over 1 hour. And dripped. Thereafter, the mixture was cooled to 60 ° C., 490 parts of methanol and 4 parts of triethylamine were added, and a half esterification reaction was performed under heating and reflux for 4 hours.

  Thereafter, the remaining methanol was removed under reduced pressure to obtain a solution of a carboxyl group-containing polymer (C-1).

  The obtained polymer solution had a solid content of 55% by mass, the number average molecular weight of this polymer was about 3,500, and the half acid value was 160 mgKOH / g.

Production of epoxy group-containing acrylic resin (D) Production example 4
A four-necked flask equipped with a stirrer, a thermometer, a condenser tube and a nitrogen gas inlet was charged with 410 parts of xylene and 77 parts of n-butanol, and the temperature was raised to 125 ° C. under nitrogen gas flow. After reaching 125 ° C., the flow of nitrogen gas was stopped, and the following monomer mixture II composed of a monomer and a polymerization initiator (2,2′-azobisisobutyronitrile) was added dropwise over 4 hours.
Monomer mixture II
Glycidyl methacrylate 432 parts n-butyl acrylate 720 parts Styrene 288 parts 2,2'-azobisisobutyronitrile 72 parts

  Next, after aging for 30 minutes while bubbling nitrogen gas at 125 ° C., a mixture of 90 parts of xylene, 40 parts of n-butanol and 14.4 parts of 2,2′-azobisisobutyronitrile was added over 2 hours. The solution was added dropwise and then aged for 2 hours to obtain a solution of an epoxy group-containing acrylic resin (D-1). The obtained epoxy group-containing acrylic resin solution had a mass solid content concentration of 70%, the epoxy group-containing acrylic resin had an epoxy group content of 2.11 mmol / g, and a number average molecular weight of 2,000.

Manufacture of top coat clear paint Production Example 5
The top coating clear paint 1 was obtained by charging each component in the following formulation (the blending amount represents the resin solid content), and stirring and mixing so as to be uniform using a rotary blade type stirrer.
Carboxyl group-containing polymer (C-1) (Production Example 3) 50 parts Epoxy group-containing acrylic resin (D-1) (Production Example 4) 50 parts Silicone compound A1 (Production Example 1) 5 parts Catalyst (* 1) 2 parts UV1164 (* 2) 2 parts HALS292 (* 3) 2 parts BYK-300 (* 4) 0.2 parts The above-mentioned notes (* 1) to (* 4) have the following meanings: .
(* 1) Catalyst: An equivalent blend of tetrabutylammonium bromide and monobutyl phosphate.
(* 2) UV1164: trade name, manufactured by Ciba Geigy Co., Ltd., ultraviolet absorber, 2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-isooctyloxyphenyl) -1, 3,5-triazine).
(* 3) HALS292: trade name, manufactured by Ciba Geigy Co., Ltd., light stabilizer, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl (1,2,2,6,6) -Mixture with pentamethyl-4-piperidyl) sebacate).
(* 4) BYK-300: trade name, manufactured by Big Chemie, surface conditioner, polyether-modified polydimethylsiloxane).

Coating film forming method Examples 10-18 and Comparative Examples 2-3
(1) “Swasol 1000” was added to the clear top coating 1 obtained in Production Example 5 and the Ford Cup No. Measured using # 4 and adjusted to a viscosity of 25 seconds at 20 ° C.
(2) A thermosetting epoxy resin-based cationic electrodeposition coating (trade name “Electron GT-10”, manufactured by Kansai Paint Co., Ltd.) is applied on a 0.8 mm thick dull steel plate subjected to zinc phosphate conversion treatment. Electrodeposition coating was performed to a film thickness of 20 μm, and the film was cured by heating at 170 ° C. for 30 minutes. Next, a polyester resin / melamine resin-based intermediate coating for automobiles (trade name “Amirac TP-65-2”, white coating color, manufactured by Kansai Paint Co., Ltd.) has a thickness of 35 μm on the electrodeposition coating film. Air spray coating as described above, and heat-cured at 140 ° C. for 30 minutes. The steel sheet on which the electrodeposition coating film and the intermediate coating film were formed was used as an object to be coated.
(3) Acrylic resin / melamine resin-based automotive topcoat base paint (trade name “water-based metallic basecoat WBC713T # 040”, white paint color, manufactured by Kansai Paint Co., Ltd.) on the article obtained in (2) above. The film was air-sprayed to a film thickness of 15 μm, allowed to stand at room temperature for 5 minutes, pre-heated at 80 ° C. for 10 minutes, and then the viscosity was adjusted on the uncured coating layer by (1) above. The overcoat clear paint 1 was spin-sprayed to a film thickness of 35 μm, left at room temperature for 10 minutes, and then heated at 140 ° C. for 20 minutes to cure the two-layer coating film together. Thus, a coating test plate was prepared in which a multi-layer top coat film composed of a base coat and a clear coat was formed on an object to be coated by a 2-coat 1-bake method.
(4) Next, a portion of the clear coat coating surface was repaired with a sander using 5989 Ultra Finish (trade name, ultrafine particle compound, abrasive) manufactured by 3M. The polishing range was a circle with a diameter of about 100 mm, and polishing was performed intensively on the dust adhering portion for 20 seconds. Further, this polished portion was lightly washed with tap water, and washed with pure water for finishing.
(5) Subsequently, the hydrophilizing agent solutions 1-10 obtained in Examples 1-9 and Comparative Example 1 and Toyota genuine carnaubaol (trade name, Toyota Motor Corporation, Carnauba Wax) ( Note: Wipe coating was performed by applying an appropriate amount of Comparative Example 3) to a polished portion using a flannel and wiping to form a uniform coating film. This coating is preferably performed so as to fill the portion where the clear coat film has been removed by polishing, and it is desirable to apply the coating to a larger area than the polished portion. After the above wipe coating, it was left at room temperature and allowed to dry naturally.

  Each coating test plate prepared as described above was evaluated by the following evaluation method. The results are shown in Table 3 below.

Evaluation method Coating workability: The workability in wipe coating of the hydrophilizing agent solution was evaluated according to the following criteria.
A: Very easy to wipe off.
○: Good with almost no problems.
Coating unevenness: The coating unevenness of the wipe coating portion of the hydrophilizing agent solution was evaluated according to the following criteria.
A: Very good with no unevenness.
○: Good with almost no problems.
Coating surface smoothness: The hydrophilization agent solution wipe coating part was visually observed and evaluated according to the following criteria.
○: Good smoothness with no crushed skin and unevenness.
X: Yuzu skin, unevenness etc. are recognized and smoothness is inferior.
20 ° gloss: Measure the 20 ° specular reflectance (20 ° gloss value) of the hydrophilization agent solution wipe coating using a handy gloss meter (trade name “HG-268”, manufactured by Suga Test Instruments Co., Ltd.) did.
For the following evaluations, a paint test board was installed for 2 months at Kansai Paint Co., Ltd. Development Center (Hiratsuka City, Kanagawa) facing the ground at an angle of 30 degrees with the ground. Evaluation was carried out without washing.
Appearance (stain): The stain on the wipe coating portion of the hydrophilizing agent solution was evaluated by the difference in brightness (ΔL) from the initial coating film. ΔL was determined by the following formula.
ΔL = (L value of initial coating film) − (L value after outdoor exposure test)
The L value is measured using a tristimulus value direct-reading color meter (trade name “CR400”, manufactured by Konica Minolta Co., Ltd.) under the conditions of a light source D65, a visual field of 2 °, and a diffuse illumination vertical light reception (d / 0). It was done in. This L value is a value based on the CIE 1976 L ^* a ^* b ^* color system.
The evaluation criteria for the degree of contamination of the coating film are as follows. The smaller the ΔL value, the better the appearance (dirt).
○: ΔL <1,
Δ: 1 ≦ ΔL <2,
X: 2 ≦ ΔL.
Water contact angle (degree): The water contact angle of the wipe coating portion of the hydrophilizing agent solution was measured.
Appearance (dirt) difference: The difference in appearance (difference in dirt) between the wipe-coated part (polished part) and the unpolished part of the hydrophilizing agent solution was visually evaluated according to the following criteria.
○: No difference is observed in the degree of soiling of both parts, which is good.
Δ: The dirt on the polished part is more advanced than the unpolished part, and there is a difference in the degree of dirt on both parts.
The
×: The dirt on the polished part is very advanced compared to the unpolished part, and the degree of dirt on both parts is remarkable.
There is a difference.

Claims (5)

  A silicone compound (A) containing at least one organic functional group selected from a mercapto group, an epoxy group, a (meth) acryloyl group, a vinyl group, a haloalkyl group and an amino group in a hydrophilic or hydrophilizable coating film; A method for forming a coating film, which comprises applying a hydrophilizing agent solution containing an organic solvent (B).   100 parts by weight of an alkoxysilane compound (a) in which the silicone compound (A) contains at least one organic functional group selected from mercapto groups, epoxy groups, (meth) acryloyl groups, vinyl groups, haloalkyl groups and amino groups, And (2) the tetraalkoxysilane compound (b) is a partially cohydrolyzed condensate of a mixture of 20 to 2,000 parts by weight.   The coating film forming method according to claim 1 or 2, wherein the hydrophilic or hydrophilizable coating film is a coating film formed from a coating composition containing the silicone compound (A).   The hydrophilic or hydrophilizable coating film is a coating film formed from a coating composition containing a carboxyl group-containing polymer (C), an epoxy group-containing acrylic resin (D) and a silicone compound (A). The coating film formation method of any one of -3.   Hydrophilic, containing silicone compound (A) and organic solvent (B) containing at least one organic functional group selected from mercapto group, epoxy group, (meth) acryloyl group, vinyl group, haloalkyl group and amino group Or the hydrophilic treatment agent solution for apply | coating on the coating film which can be hydrophilized, and forming a hydrophilic treatment coating film on this coating film.