JP6912849B2 - Coating composition and method for forming a multi-layer coating film - Google Patents

Description

The present invention relates to a coating composition capable of forming a coating film having excellent water repellency, oil repellency, scratch resistance and adhesiveness, and a coating film forming method using the same.

In general, a coating film having excellent water repellency and oil repellency has been studied because a surface having high water repellency and oil repellency is hard to be soiled and has excellent stain resistance.

As a coating composition capable of forming a coating film having excellent water repellency and oil repellency, those containing a compound to which a functional group containing fluorine such as a fluoroalkyl group is applied are known. However, when the water- and oil-repellent coating film containing fluorine obtained by coating such a coating composition is decomposed and discarded, the diffusion of fluorine into the environment has become a problem. As a composition for forming a coating film that exhibits water repellency and oil repellency without containing fluorine, Patent Document 1 has a modified silicone compound, a compound having an isocyanate group or a urethane bond, a compound having an epoxy group, and a hydroxyl group. A coating composition for forming a water- and oil-repellent film is described, which comprises at least one compound selected from a compound, a (meth) acrylic compound, an amino compound, a maleimide compound, and a thiol compound. However, according to Examples, the composition described in Patent Document 1 requires drying and curing at a high temperature of 180 ° C., and may not be applicable to organic materials that are sensitive to high temperatures.

Further, in general, the surface of an article is required to be hard to be scratched, but the composition described in Patent Document 1 does not consider scratch resistance and does not mention the adhesiveness of a coating film.

JP 2016-30763

An object of the present invention is to provide a coating composition and a method for forming a multi-layer coating film capable of forming a coating film having excellent water repellency, oil repellency, scratch resistance and adhesiveness.

According to one aspect of the invention
Item 1. A hydroxyl group-containing acrylic resin (A) having a glass transition temperature (Tg) in the range of 10 ° C. to 85 ° C., and a silicone compound having one or more reactive groups and having a weight average molecular weight of 500 to 10,000. A coating composition containing B) and a polyisocyanate compound (C).
The initial water contact angle of the coating film formed by coating the surface to be coated so as to be 35 μm as a cured coating film is within the range of 90 to 110 °, and the initial oleic acid contact angle is 40 to 60 °. Within range
A coating composition in which the retention rates of the water contact angle and the oleic acid contact angle after immersing the coating film in warm water at 90 ° C. for 300 hours are 90% or more of the respective initial contact angles.
Item 2. The hydroxyl group-containing acrylic resin (A) has a glass transition temperature (Tg) in the range of 10 ° C. to 50 ° C., and the hydroxyl group-containing acrylic resin (A1) and the glass transition temperature (Tg) are in the range of 51 ° C. to 85 ° C. The coating composition according to claim 1, which comprises an acrylic resin (A2).
Item 3. The coating composition according to claim 1 or 2, wherein the silicone compound (B) has a polysiloxane skeleton.
Item 4. 6. A method for forming a multi-layer coating film by coating a coating composition to form a clear coating film,
Item 5. A colored paint containing a colored pigment is applied onto an object to be coated to form a colored coating film, and a brilliant paint containing a brilliant pigment is applied onto the formed colored coating film to form a brilliant coating film. A method for forming a multi-layer coating film, wherein the coating composition according to any one of claims 1 to 3 is applied onto the formed bright coating film to form a clear coating film.
Item 6. The method for forming a multi-layer coating film according to claim 4 or 5, wherein the colored coating film and / or the brilliant coating film and the clear coating film are heated to a temperature of 60 ° C. to 150 ° C. and cured at the same time.
Is provided.

According to the coating composition of the present invention and the method for forming a multi-layer coating film, a coating film having excellent water repellency, oil repellency, scratch resistance and adhesiveness can be obtained.

The coating composition of the present invention has a hydroxyl group-containing acrylic resin (A) having a glass transition temperature (Tg) in the range of 10 ° C. to 85 ° C., one or more reactive groups, and a weight average molecular weight of 500 to 10. A coating composition containing a silicone compound (B) and a polyisocyanate compound (C), which is 000, and is initially formed by coating the surface to be coated with a cured coating film having a thickness of 35 μm. The water contact angle is in the range of 90 to 110 °, the initial oleic acid contact angle is in the range of 40 to 60 °, and the water contact after immersing the coating film in warm water at 90 ° C. for 300 hours. The retention rate of the angle and the oleic acid contact angle is 90% or more of each initial contact angle.

Hydroxy group-containing acrylic resin (A)
The hydroxyl group-containing acrylic resin (A) has a glass transition temperature (Tg) in the range of 10 ° C. to 85 ° C., preferably 10 to 82 ° C., and more preferably 10 ° C. to 80 ° C.

The hydroxyl group-containing acrylic resin (A) uses, for example, a method known per se from a hydroxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer, for example, organic. It can be produced by copolymerizing by a method such as a solution polymerization method in a solvent or an emulsion polymerization method in water.

The hydroxyl group-containing polymerizable unsaturated monomer is a compound having one or more hydroxyl groups and one or more polymerizable unsaturated bonds in one molecule. Examples of the hydroxyl group-containing polymerizable unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Monoesterate of (meth) acrylic acid and divalent alcohol having 2 to 8 carbon atoms; ε-caprolactone modified product of monoesteride of (meth) acrylic acid and divalent alcohol having 2 to 8 carbon atoms; N -Hydroxymethyl (meth) acrylamide; allyl alcohol, (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end, and the like can be mentioned. These can be used alone or in combination of two or more.

The blending ratio of the hydroxyl group-containing polymerizable unsaturated monomer is 5 to 30% by mass, particularly 10 to 30% by mass, and more particularly 10 to 25% by mass with respect to the total amount of the monomer components. preferable.
Other polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer The other polymerizable unsaturated monomer copolymerizable is one unsaturated in one molecule other than the above-mentioned hydroxyl group-containing polymerizable unsaturated monomer. It is a compound having a saturated bond, and specific examples thereof are listed below (1) to (8).
(1) Acid group-containing polymerizable unsaturated monomer: A compound having one or more acid groups and one unsaturated bond in one molecule, for example, (meth) acrylic acid, crotonic acid, itaconic acid, malein. Carboxyl group-containing polymerizable unsaturated monomers such as acids and maleic anhydride; sulfonic acid group-containing polymerizable unsaturated monomers such as vinyl sulfonic acid and sulfoethyl (meth) acrylate; 2- (meth) acryloyloxyethyl acid phosphate, Acidic phosphate ester-based polymerizable unsaturated monomers such as 2- (meth) acryloyloxypropyl acid phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, 2-methacryloyloxyethylphenyl phosphate, etc. be able to. These can be used alone or in combination of two or more.

(2) Monoesteride of acrylic acid or methacrylic acid and a monovalent alcohol having 1 to 20 carbon atoms: for example, methyl (meth) acrylate, ethyl (meth) crylate, propyl (meth) acrylate, n-butyl (meth). Acrylate, Isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isomyristyl (meth) acrylate, isostearyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name) ), Lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, etc.
(3) Aromatic polymerizable unsaturated monomer: For example, styrene, α-methylstyrene, vinyltoluene and the like.

When the aromatic polymerizable unsaturated monomer is used as a constituent component, the blending ratio thereof is preferably in the range of 3 to 50% by mass, particularly 5 to 40% by mass, based on the total amount of the monomer components.

(4) Glycidyl group-containing polymerizable unsaturated monomer: A compound having one glycidyl group and one unsaturated bond in one molecule, specifically, glycidyl acrylate, glycidyl methacrylate and the like.
(5) Nitrogen-containing polymerizable unsaturated monomer: For example, acrylamide, methacrylamide, dimethylacrylamide, N, N-dimethylpropylacrylamide, N-butoxymethylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, diacetoneacrylamide, N, N-dimethylaminoethyl (meth) acrylate, vinylpyridine, vinylimidazole, etc.
(6) Alicyclic hydrocarbon group-containing polymerizable unsaturated monomer: For example, cyclohexyl (meth) acrylate, methylcyclohexylmethyl (meth) acrylate (for example, 4-methylcyclohexylmethyl (meth) acrylate), ethylcyclohexylmethyl (meth). ) Acrylate (eg 4-ethylcyclohexylmethyl (meth) acrylate), methoxycyclohexylmethyl (meth) acrylate (eg 4-methoxycyclohexylmethyl (meth) acrylate), tert-butylcyclohexyl (meth) acrylate, cyclooctyl (meth) ) Cycloalkyl (meth) acrylates such as acrylates and cyclododecyl (meth) acrylates; isobornyl (meth) acrylates, tricyclodecanyl (meth) acrylates, adamantyl (meth) acrylates, 3,5-dimethyladamantyl (meth) acrylates, Examples thereof include 3-tetracyclododecyl (meth) acrylate, and preferred examples thereof include cyclohexyl (meth) acrylate and isobornyl (meth) acrylate.

(7) Other vinyl compounds: For example, vinyl acetate, vinyl propionate, vinyl chloride, Beova 9 which is a vinyl ester of versatic acid, Beova 10 (Japan epoxy resin) and the like.
(8) Unsaturated bond-containing nitrile compound: For example, acrylonitrile, methacrylonitrile and the like.

As these other polymerizable unsaturated monomers, one kind or two or more kinds can be used.
In the present specification, "(meth) acrylate" means acrylate or methacrylate, and "(meth) acrylic acid" means acrylic acid or methacrylic acid. Further, "(meth) acryloyl" means acryloyl or methacryloyl, and "(meth) acrylamide" means acrylamide or methacrylamide.
The hydroxyl group-containing acrylic resin (A) has the above-mentioned polymerizable property so that the glass transition temperature is within the range of 10 ° C. to 85 ° C. from the viewpoint of water repellency, oil repellency, scratch resistance and adhesiveness of the obtained coating film. Determine the blending ratio of unsaturated monomers.

Further, the hydroxyl group-containing acrylic resin (A) has a glass transition temperature (Tg) of 10 ° C to 50 ° C, preferably 10 to 40, from the viewpoint of water repellency, oil repellency, scratch resistance and adhesiveness of the obtained coating film. The hydroxyl group-containing acrylic resin (A1) and the glass transition temperature (Tg) in the range of ° C., more preferably 12 to 30 ° C. are 51 ° C. to 85 ° C., preferably 60 to 82 ° C., still more preferably 65 ° C. to 80 ° C. It is preferable to contain a hydroxyl group-containing acrylic resin (A2) within the range of.

In the coating composition of the present invention, when the hydroxyl group-containing acrylic resin (A) contains a hydroxyl group-containing acrylic resin (A1) and a hydroxyl group-containing acrylic resin (A2), the hydroxyl group-containing acrylic resin (A1) and the hydroxyl group-containing acrylic resin The compounding ratio with (A2) is 50/50 to 99/1, preferably 70/30 to 95/5, and more preferably 80/20 to 90/10, and the stain resistance of the obtained coating film is high. , Suitable from the viewpoint of scratch resistance and adhesiveness.

In the present specification, the glass transition temperature Tg of the hydroxyl group-containing acrylic resin is a value calculated by the following formula.
1 / Tg (K) = W1 / T1 + W2 / T2 + ... Wn / Tn
Tg (° C.) = Tg (K) -273
In the formula, W1, W2, ... Wn is the mass fraction of each monomer, and T1, T2 ... Tn is the glass transition temperature Tg (K) of the homopolymer of each monomer.
The glass transition temperature of the homopolymer of each monomer is determined by POLYMER HANDBOOK Fourth Edition, J. Mol. Brandrup, E.I. h. Immunogut, E.I. A. The glass transition temperature of a monomer, which is a value according to Grulke (1999) and is not described in the document, is obtained by synthesizing a homopolymer of the monomer so that the weight average molecular weight is about 50,000, and the glass transition thereof. Use the value when the temperature is measured by differential scanning calorimetry.

Further, in the present specification, the weight average molecular weight and the number average molecular weight are the retention times (retention capacity) measured using a gel permeation chromatograph (GPC), and the retention time (retention capacity) of standard polystyrene having a known molecular weight measured under the same conditions. It is a value obtained by converting the molecular weight of polystyrene by (retention capacity). The columns are "TSKgel G-4000H x L", "TSKgel G-3000H x L", "TSKgel G-2500H x L", "TSKgel G-2000H x L" (all manufactured by Tosoh Corporation, trade name). ), Mobile phase; tetrahydrofuran, measurement temperature; 40 ° C., flow velocity; 1 ml / min, detector; RI conditions.

The weight average molecular weight of the hydroxyl group-containing acrylic resin (A) is 5,000 to 100,000, preferably 7,000 to 50,000, more preferably 7,000 to 50,000, from the viewpoint of weather resistance, finish and adhesion of the coating film. It is preferably in the range of 8,000 to 30,000.

The hydroxyl value of the hydroxyl group-containing acrylic resin (A) is preferably in the range of 10 to 200 mgKOH / g, preferably 50 to 150 mgKOH / g, and more preferably 40 to 150 mgKOH / g from the viewpoint of curability and water resistance.

Silicone compound (B)
The coating composition of the present invention has one or more reactive groups from the viewpoint of water repellency, oil repellency and adhesive scratch resistance of the obtained coating film, and has a weight average molecular weight of 500 to 10,000, preferably 1. It contains a silicone compound (B) of 000 to 8,000, more preferably 2,000 to 5,000. The weight average molecular weight was measured in the same manner as in the method described in the column of the hydroxyl group-containing acrylic resin (A).

Examples of the reactive group include an amino group, a hydroxyl group, an epoxy group which may be an alicyclic group, a (meth) acryloyl group, a mercapto group, a carboxyl group, an alkoxy group, an isocyanate group and a silanol group.

The silicone compound (B) preferably has a polysiloxane skeleton, preferably a polydimethylsiloxane skeleton, from the viewpoint of water repellency, oil repellency and scratch resistance of the obtained coating film.

The silicone compound (B) has a reactive group introduced into a part of the side chain of the polysiloxane, one end or both ends of the polysiloxane, and one end or both ends in addition to the side chain of the polysiloxane. preferable.

Among them, the preferable silicone-based compound (B) can be represented by the following formulas (I) to (III).

(In the formula, n represents a number of 2 to 150, preferably 4 to 100, more preferably 4 to 60, and R ¹ may be the same or different from each other as a phenyl group or 1 to 6 carbon atoms, preferably 1. ~ 4, more preferably 1-2 alkyl groups, R ² represents 1-6 carbon atoms, preferably 1-4, more preferably 1-2 alkylene groups; X is an amino group, hydroxyl group, fat. Indicates a group selected from an epoxy group which may be cyclic, a (meth) acryloyl group, a mercapto group, a carboxyl group, an alkoxy group, an isocyanate group and a silanol group).
Specific examples of the silicone compound (B) are listed below (1) to (8).
(1) Silicone oil having an epoxy group in its molecular structure: "KF-105", "X-22-163A", "X-22-163B", "X-22-163C" having epoxy groups at both ends. , "X-22-169AS", "X-22-169B" having an alicyclic epoxy group at both ends, "X-22-343", "X-22-2000" having an epoxy group in the side chain. , "X-22-4741", "X-22-2046" having an alicyclic epoxy group in the side chain (all manufactured by Shin-Etsu Chemical Industry Co., Ltd.) and the like.
(2) Silicone oil having an amino group in its molecular structure: "KF-8010", "X-22-161A", "X-22-161B", "KF-8012", "KF-8012" having amino groups at both ends. "X-22-9409", "X-22-1660B-3" (all manufactured by Shin-Etsu Chemical Co., Ltd.), "BY-16-853U", "BY-16-853", "BY-16-853B" ( (Manufactured by Toray Dow Corning Co., Ltd.), "KF-880", "KF-8004" (manufactured by Shin-Etsu Chemical Co., Ltd.), etc., which have an amino group in the side chain.
(3) Silicone oil having hydroxyl groups in its molecular structure: "KF-6000", "KF-6001", "KF-6002", "KF-6003" having hydroxyl groups at both ends, phenolic hydroxyl groups at both ends "X-22-1821" (manufactured by Shin-Etsu Chemical Industry Co., Ltd.), "BY-16-752A" (manufactured by Toray Dow Corning Co., Ltd.), "X-22-170BX" having a hydroxyl group at one end, "X-22-170BX""X-22-176DX" (above, manufactured by Shinetsu Chemical Industry Co., Ltd.), "X-22-4039" having a hydroxyl group on the side chain, "X-22-4015" (above, manufactured by Shinetsu Chemical Industry Co., Ltd.), both ends "SF8427" (manufactured by Toray Dow Corning), "X-22-4952" (manufactured by Shinetsu Chemical Industry Co., Ltd.) having a hydroxyl group in the polyether; "FZ-2162", "FZ-2162" having a hydroxyl group in the side chain polyether. SH3773M ”(above, manufactured by Toray Dow Corning), etc.
(4) Silicone oil having a methacrylic group in its molecular structure: "X-22-164A", "X-22-164B" (all manufactured by Shin-Etsu Chemical Co., Ltd.) and the like having methacrylic groups at both ends.
(5) Silicone oil having a mercapto group in its molecular structure: "X-22-167B" having a mercapto group at both ends, "KF-2001" having a mercapto group in the side chain (all manufactured by Shin-Etsu Chemical Co., Ltd.) etc.
(6) Silicone oil having a carboxyl group in its molecular structure: "X-22-162C" having a carboxyl group at both ends and "X-22-3710" having a carboxyl group at one end (functional group equivalent 1450 g / mol) (above, manufactured by Shin-Etsu Chemical Industry Co., Ltd.), etc.

As the silicone compound (B) in the coating composition of the present invention, one type can be selected and used from the above, but two or more types may be mixed and used.

The content of the silicone compound (B) in the coating composition of the present invention is 0 with respect to 100 parts by mass of the solid content of the hydroxyl group-containing acrylic resin (A) from the viewpoint of water repellency and oil repellency of the obtained coating film. It is preferably in the range of .05 to 1.0 parts, more preferably in the range of 0.1 to 0.7 parts, and particularly preferably in the range of 0.15 to 0.5 parts.

Polyisocyanate compound (C)
The coating composition of the present invention contains the polyisocyanate compound (C) from the viewpoint of adhesiveness.

The polyisocyanate compound (C) is a compound having at least two isocyanate groups in one molecule, and is, for example, an aliphatic polyisocyanate, an alicyclic polyisocyanate, an aromatic aliphatic polyisocyanate, an aromatic polyisocyanate, or the like. Examples thereof include derivatives of polyisocyanates.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, and 1,3. An aliphatic diisocyanate such as −butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, diisocyanate dimerate, methyl 2,6-diisocyanatohexanate (common name: lysine diisocyanate); 2 , 6-Diisocyanatohexanoic acid 2-isocyanatoethyl, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1, , 8-Diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane and other aliphatic triisocyanates, etc. Can be mentioned.

Examples of the alicyclic polyisocyanate include 1,3-cyclopentenediisocyanate, 1,4-cyclohexanediisocyanate, 1,3-cyclohexanediisocyanate, and 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate (common name). : Isophorone diisocyanate), 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, 1,3- or 1,4-bis (isocyanato) Alicyclic diisocyanates such as methyl) cyclohexane (common name: hydrogenated xylylene diisocyanate) or a mixture thereof, methylenebis (4,1-cyclohexanediyl) diisocyanate (common name: hydrogenated MDI), norbornan diisocyanate; 1,3,5 -Triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2,2,1) heptane, 2- (3-Isocyanatopropyl) -2,6-di (isocyanatomethyl) -bicyclo (2,2,1) heptane, 3- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl)- Bicyclo (2,2,1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2,2,1) heptane, 6- (2) -Isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2,2,1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-Isocyanatopropyl) -bicyclo (2,2,1) -heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2,2) , 1) Alicyclic triisocyanates such as heptane can be mentioned.

Examples of the aromatic aliphatic polyisocyanate include methylenebis (4,1-phenylene) diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω'-diisocyanato-. Arophilic aliphatic diisocyanates such as 1,4-diethylbenzene, 1,3- or 1,4-bis (1-isocyanato-1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or a mixture thereof; 1,3 , 5-Arophilic aliphatic triisocyanates such as triisocyanatomethylbenzene and the like can be mentioned.

Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylenedi isocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, and 2,4-tolylene diisocyanate (common name: 2,4-tolylene diisocyanate). TDI) or 2,6-tolylene diisocyanate (common name: 2,6-TDI) or a mixture thereof, aromatic diisocyanates such as 4,4'-toluene diisocyanate and 4,4'-diphenyl ether diisocyanate; triphenylmethane-4 , 4', 4''-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene and other aromatic triisocyanates; 4,4'-diphenylmethane-2,2' , 5, 5'-Tetraisocyanate and other aromatic tetraisocyanates and the like.

Examples of the polyisocyanate derivative include the above-mentioned polyisocyanate dimer, trimmer, biuret, allophanate, uretdione, uretoimine, isocyanurate, oxadiazine trione, and polymethylene polyphenyl polyisocyanate (Crude MDI, Polymeric MDI). , Crude TDI and the like.

As the polyisocyanate compound (C), the above-mentioned aliphatic diisocyanate, alicyclic diisocyanate and derivatives thereof can be preferably used from the viewpoint of adhesiveness and the like.

Further, as the polyisocyanate compound, a prepolymer obtained by reacting the polyisocyanate and its derivative with a compound capable of reacting with the polyisocyanate under the condition of excess isocyanate group may be used. Examples of the compound capable of reacting with the polyisocyanate include compounds having an active hydrogen group such as a hydroxyl group and an amino group. Specific examples thereof include polyhydric alcohols, low molecular weight polyester resins, amines and water. Can be used.

The polyisocyanate compound includes a polymer of an isocyanate group-containing polymerizable unsaturated monomer, or a polymerizable unsaturated monomer other than the isocyanate group-containing polymerizable unsaturated monomer and the isocyanate group-containing polymerizable unsaturated monomer. A copolymer may be used.

Further, the polyisocyanate compound may be a polyisocyanate compound in which an isocyanate group is blocked with a blocking agent, that is, a so-called blocked polyisocyanate compound.

Examples of the blocking agent include phenol-based agents such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; Oximes such as γ-butyrolactam and β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol and lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono Ether systems such as butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, lactic acid. Alcohols such as butyl, methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketooxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime, etc. Oxime-based; active methylene-based such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone; butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thio Mercaptans such as phenol, methylthiophenol, ethylthiophenol; acidamides such as acetoanilide, acetoaniside, acetotolide, acrylamide, methacrylicamide, acetateamide, stearate amide, benzamide; succinide imide, phthalateimide, maleateimide, etc. Imid-based; diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenylamine and other amine-based; imidazole, 2-ethylimidazole and other imidazole-based; urea, thiourea , Ethyleneurea, ethylenethiourea, diphenylurine Urea type such as element; Carbamic acid ester type such as N-phenylcarbamic acid phenyl; Imine type such as ethyleneimine and propyleneimine; Sulfite type such as sodium bisulfite and potassium bisulfite; Azole type compound and the like can be mentioned. .. Examples of the azole compound include pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3, Pyrazole or pyrazole derivatives such as 5-dimethylpyrazole, 3-methyl-5-phenylpyrazole; imidazole or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole; 2-methylimidazoline , 2-Pyrazole imidazoline and other imidazoline derivatives and the like.

Among them, preferred blocking agents include oxime-based blocking agents, active methylene-based blocking agents, pyrazoles or pyrazole derivatives.

When blocking (reacting the blocking agent), a solvent can be added as needed. The solvent used for the blocking reaction may be one that is not reactive with the isocyanate group. For example, acetone, ketones such as methyl ethyl ketone, esters such as ethyl acetate, and N-methyl-2-pyrrolidone (NMP). Such solvents can be mentioned.

The polyisocyanate compound (C) can be used alone or in combination of two or more.

In the coating composition of the present invention, the compounding ratio of the polyisocyanate compound (C) is the isocyanate group (including the blocked isocyanate group) of the polyisocyanate compound and the hydroxyl group-containing acrylic resin (A) from the viewpoint of adhesiveness. The equivalent ratio (NCO / OH) with the hydroxyl group can be determined to be in the range of 0.5 to 2.0, particularly preferably 0.6 to 1.5.

In addition, the coating composition of the present invention can contain a urethanization reaction catalyst.

Specific examples of the urethanization reaction catalyst include tin octylate, dibutyltin diacetate, dibutyltin di (2-ethylhexanoate), dibutyltin dilaurate, dioctyltin diacetate, and dioctyltindi (2). -Ethylhexanoate), dibutyltin oxide, dibutyltin sulfite, dioctyltin oxide, dibutyltin fatty acid salt, lead 2-ethylhexanoate, zinc octylate, zinc naphthenate, fatty acid zincs, bismuth octanate, 2- Organic metal compounds such as bismuth ethylhexanoate, bismuth oleate, bismuth neodecanoate, bismuth versaticate, bismuth naphthenate, cobalt naphthenate, calcium octylate, copper naphthenate, tetra (2-ethylhexyl) titanate; tertiary amine Etc., and these can be used individually or in combination of two or more.

When the urethanization reaction catalyst is used, the amount of catalyst is in the range of 0.0001 to 0.5% by mass, particularly 0.0005 to 0.1% by mass, based on the total solid content of the coating composition. It is preferably inside.

When the coating composition of the present invention contains the above-mentioned urethanization reaction catalyst, acetic acid, propionic acid, butyric acid, isopentanoic acid, hexanoic acid, 2-ethylbutyric acid, naphthenic acid and octyl acid are used from the viewpoint of storage stability and curability. , Nonanoic acid, decanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, neodecanoic acid, versatic acid, isobutyric anhydride, itaconic anhydride, acetic anhydride , Organic acids such as citraconic anhydride, propionic anhydride, maleic anhydride, butyric anhydride, citric anhydride, trimellitic anhydride, pyromellitic anhydride, phthalic anhydride; inorganic acids such as hydrochloric acid and phosphoric acid; acetylacetone, imidazole-based It may contain a metal coordinating compound such as a compound.

The coating composition of the present invention contains a solvent, a pigment, an ultraviolet absorber, a light stabilizer, an antioxidant, a surface conditioner, an antifoaming agent, an emulsifier, and a surfactant, as long as the water repellency and oil repellency are not impaired. Other additive components usually used in the field of coating such as an agent, an antifouling agent, a wetting agent, a thickener, a dye, and a gloss adjusting agent can be appropriately contained.

The coating composition of the present invention may be in the form of a melt, a solution, a suspension, or an emulsion, but the form of a solution in which a hydroxyl group-containing acrylic resin is dissolved in a solvent is used for productivity and It is preferable from the viewpoint of workability. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and ethylene glycol monobutyl ether, esters such as ethyl acetate and butyl acetate, and toluene. , Aromatic hydrocarbons such as xylene, alcohols such as methanol, ethanol, propanol and butanol, tetrahydrofuran, dimethylformamide, petroleum hydrocarbons and the like.

Examples of the pigment include bright pigments, coloring pigments, extender pigments and the like. The pigment can be used alone or in combination of two or more.

Examples of the brilliant pigment include aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, glass flakes, aluminum oxide, mica, titanium oxide and / or aluminum oxide coated with iron oxide, titanium oxide and the like. / Or an iron oxide-coated mica or the like.

Examples of the coloring pigment include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindolin pigment, slene pigment, and perylene. Examples thereof include based pigments, dioxazine based pigments, and diketopyrrolopyrrole based pigments.

Examples of the extender pigment include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, alumina white and the like.

When the coating composition of the present invention contains the above pigment, the content of the pigment is 1 to 70% by mass, preferably 5 to 60% by mass, more preferably 5 to 60% by mass, based on the total solid content of the coating composition. It is preferably in the range of 15 to 50% by mass.

The coating composition of the present invention may be a one-component coating material, and may contain a main agent containing a hydroxyl group-containing acrylic resin (A) and a silicone compound (B), a curing agent containing a polyisocyanate compound (C), and the like. May be a multi-component paint used by mixing before painting.

Water contact angle In the coating composition of the present invention, the initial water contact angle of the coating film formed by coating the surface to be coated so as to be 35 μm as a cured coating film is 90 to 110 °, preferably 95 to 110 °. , More preferably in the range of 98-110 °.

Here, the water contact angle refers to the contact angle (unit: °) after 5 seconds have passed by dropping 0.4 μL of distilled water onto the obtained coating film. The contact angle meter used for the contact angle measurement in the present specification is "CA-X150 type" (manufactured by Kyowa Interface Science Co., Ltd.).

In the present specification, the initial water contact angle is a coating film formed after 72 hours or more, and various resistance tests such as a water resistance test, a weather resistance test, a scratch resistance test, and a stain resistance test are used. The water contact angle of the coating film that has not been used in the above.

Oleic acid contact angle In the coating composition of the present invention, the initial oleic acid contact angle of the coating film formed by coating the surface to be coated so as to be 35 μm as a cured coating film is 40 to 55 °, preferably 44 to 44 to. It is in the range of 55 °, more preferably 45 to 55 °.

Here, the oleic acid contact angle refers to the contact angle (unit: °) after 5 seconds have passed by dropping 0.4 μL of oleic acid onto the obtained coating film. The contact angle meter used for the contact angle measurement in the present specification is "CA-X150 type" (manufactured by Kyowa Interface Science Co., Ltd.).
In the present specification, the initial oleic acid contact angle is a coating film formed after 72 hours or more, and has various resistances such as water resistance test, weather resistance test, scratch resistance test, and stain resistance test. The oleic acid contact angle of a coating film that has not been tested.

Water contact angle and oleic acid contact angle after water resistance test In the coating composition of the present invention, a coating film formed by coating a surface to be coated with a cured coating film of 35 μm is placed in warm water at 90 ° C. for 300 hours. The retention rates of the water contact angle and the oleic acid contact angle after immersion are 90% or more of the respective initial contact angles.

Here, the retention rate of the contact angle is defined by the following equation.

Retention rate (%) = contact angle after water resistance test / initial contact angle x 100
The coating composition in the present invention maintains water repellency and oil repellency not only in the initial stage immediately after the coating film is formed, but also in the coating film that has been swollen and weakened by a water resistance test. It can be said that it has excellent water repellency and oil repellency.

Multi-layer coating film forming method In the multi-layer coating film forming method of the present invention, a colored coating film containing a hydroxyl group-containing resin and a coloring pigment is coated on an object to be coated to form a colored coating film, and the colored coating film is formed. A method for forming a multi-layer coating film is included, wherein the coating composition of the present invention is applied onto the coating film to form a clear coating film.

Further, in another method for forming a multi-layer coating film of the present invention, a colored coating film containing a coloring pigment is applied on an object to be coated to form a colored coating film, and the formed colored coating film contains a brilliant pigment. The present invention includes a method for forming a multi-layer coating film, which comprises coating a brilliant coating material to form a brilliant coating film, and then coating the formed brilliant coating film with the coating composition of the present invention to form a clear coating film.

The material to be coated is not particularly limited, and may be an inorganic material, an organic material, or a hybrid material of organic and inorganic.

Examples of the inorganic material include metal materials such as iron, aluminum, brass, copper, tin, stainless steel, zinc-plated steel, and zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.) plated steel; glass; Examples include cement; concrete; polysiloxane, and the like.

The organic material is a material containing an organic resin, and examples of the organic resin include acrylic resins such as polymethylmethacrylate, polyethylene terephthalate, polyethylene naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and polyethylene-1. Polyester resins such as 2-diphenoxyetane-4, 4'-dicarboxylate, polybutylene terephthalate, and epoxy resins represented by commercial products such as Epicoat (trade name: Yuka Shell Epoxy Co., Ltd.). Polycarbonate resin, polyimide resin, novolak resin, phenol resin, acrylonitrile-butadiene-styrene (ABS) resin, vinylidene chloride resin, polyurethane resin, cellulose ester (eg, triacetyl cellulose, diacetyl cellulose, propionyl cellulose, butyryl cellulose, acetyl propionyl) Cellulose, nitrocellulose), polyamide, polystyrene (eg, syndiotactic polystyrene), polyolefin (eg, polypropylene, polyethylene, polymethylpentene), polysulfone, polyethersulfone, polyarylate, polyetherimide, polyetherketone, etc. Be done.

Further, the organic material may contain pigments and / or fibers as a part of its components.

Examples of the pigment include calcium carbonate, silica, barium sulfate, barium carbonate, talc, clay, kaolin, aluminum hydroxide, magnesium oxide, aluminum oxide and the like.

Further, examples of the fiber include glass fiber, aramid fiber, carbon fiber, cellulose fiber and the like.

Therefore, various fiber reinforced plastic materials (Fiber Reinforced Plastics: hereinafter referred to as FRP material or simply FRP) are included in the above organic materials.

As the material of the object to be coated, an organic material is preferable from the viewpoint of adhesiveness and the like, and among them, an organic material having a relatively low melting point, for example, an acrylic resin, an ABS resin, an FRP or the like is preferable.

The shape of the object to be coated may be flat or three-dimensional, and may be, for example, a film and a substrate, or a three-dimensionally processed molded product.

The object to be coated may be a product coated with a degreasing treatment, a surface treatment and a primer composition.

Colored Paint The colored paint in the method for forming a multi-layer coating film of the present invention contains a hydroxyl group-containing resin and a colored pigment.

The hydroxyl group-containing resin is a resin having at least one hydroxyl group in one molecule. Examples of the hydroxyl group-containing resin include resins having a hydroxyl group, such as polyester resin, acrylic resin, polyether resin, polycarbonate resin, polyurethane resin, epoxy resin, and alkyd resin. These can be used alone or in combination of two or more.

The hydroxyl group-containing resin preferably has a hydroxyl value of 10 to 200 mg / KOH from the viewpoint of curability and adhesiveness, and particularly from the viewpoint of weather resistance and adhesiveness, methyl methacrylate 30 is based on the total amount of the copolymerized monomer components. It is preferable to contain a hydroxyl group-containing acrylic resin (L) containing ~ 80% by mass.

Hydroxy group-containing acrylic resin (L)
The hydroxyl group-containing acrylic resin (L) is a method known per se for a hydroxyl group-containing polymerizable unsaturated monomer (a) and another polymerizable unsaturated monomer (b) copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer. It can be produced by copolymerizing with. In particular, the hydroxyl group-containing acrylic resin (L) preferably contains 20 to 85% by mass of methyl methacrylate based on the total amount of the copolymerization monomer components.

The hydroxyl group-containing polymerizable unsaturated monomer (a) and the other polymerizable unsaturated monomer (b) copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer are described in the hydroxyl group-containing acrylic resin (A), respectively. Can be mentioned.

From the viewpoint of adhesiveness, the amount of methyl methacrylate in the hydroxyl group-containing acrylic resin (L) is preferably in the range of 20 to 85% by mass, more preferably 40 to 80% by mass, based on the total amount of the copolymerized monomer components. When a hydroxyl group-containing acrylic resin (L) having methyl methacrylate in the above range is used for the colored paint, a coating film having excellent adhesion is formed even if the colored paint is directly applied without applying a primer to the object to be coated. be able to. In addition, it is also excellent in interlayer adhesion with a clear coating film.

The weight average molecular weight of the hydroxyl group-containing acrylic resin (L) is generally 1,000 to 200,000, particularly from the viewpoint of weather resistance and finish of the coating film and interlayer adhesion between the object to be coated and the clear coating film described later. It is preferably in the range of 2,000 to 100,000, more preferably 3,000 to 90,000 in general.

The hydroxyl value of the hydroxyl group-containing acrylic resin (L) is preferably in the range of 10 to 200 mgKOH / g and more preferably 40 to 150 mgKOH / g from the viewpoint of curability and water resistance.

The glass transition temperature of the hydroxyl group-containing acrylic resin (L) is preferably in the range of 15 to 90 ° C., more preferably 20 to 80 ° C. from the viewpoint of coating film hardness.

Hydroxy Group-Containing Polyester Resin A hydroxyl group-containing polyester resin can usually be obtained by copolymerizing a conventionally known polybasic acid and a polyhydric alcohol as main components according to a conventional method. Examples of the polybasic acid include adipic acid, succinic acid, isophthalic acid, terephthalic acid, phthalic acid anhydride, maleic anhydride, trimellitic acid, hexahydrophthalic anhydride, sodium 5-sulfoisophthalate, and the like. Examples of the alcohol include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, neopentyl glycol, 1,6-hexanediol, pentaerythritol, sorbitol, tris (2-hydroxyethyl) isocyanurate and the like. Further, fatty acids such as dehydrated castor oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, and tall oil fatty acid, monobasic acid such as benzoic acid, and fats and oils can be used as the copolymerization monomer component. From the viewpoint of interlayer adhesion between the object to be coated and the clear paint, it is preferable to use a hydroxyl group-containing polyester resin in which a part or all of the polyhydric alcohol component is tris (2-hydroxyethyl) isocyanurate.

From the viewpoint of curability and adhesiveness, the hydroxyl group-containing polyester resin preferably has a hydroxyl value in the range of 10 to 200 mgKOH / g and further preferably 60 to 150 mgKOH / g.

From the viewpoint of finishability, the weight average molecular weight of the hydroxyl group-containing polyester resin is preferably in the range of 5,000 to 20,000, more preferably 1,000 to 10,000.

When a hydroxyl group-containing resin other than the hydroxyl group-containing acrylic resin (L) and / or the hydroxyl group-containing polyester resin is used in combination with the coloring paint, the hydroxyl value of the other hydroxyl group-containing resin has adhesiveness, curability, and water resistance. From the viewpoint of sex, the range of 10 to 200 mgKOH / g is preferable. The weight average molecular weight of the other hydroxyl group-containing resin is generally preferably in the range of 1,000 to 200,000, particularly preferably 2,000 to 100,000 from the viewpoint of finishability and adhesiveness.

The solid content of the hydroxyl group-containing acrylic resin (L) is 100 parts by mass or less, more 2 to 85 parts by mass, based on 100 parts by mass of the hydroxyl group-containing resin in the colored paint, from the viewpoint of finishability, adhesiveness, and coating hardness. It is preferably in the range of parts by mass, more particularly 4 to 65 parts by mass.

The solid content of the hydroxyl group-containing polyester resin is 100 parts by mass or less, and further 15 to 98 parts by mass with respect to 100 parts by mass of the hydroxyl group-containing resin in the colored paint, in terms of finishability, adhesiveness, and coating hardness. Further, it is particularly preferably in the range of 35 to 96 parts by mass.

The solid content of the other hydroxyl group-containing resin is preferably 50 parts by mass or less, more preferably 5 to 30 parts by mass, based on 100 parts by mass of the hydroxyl group-containing resin in the coloring paint.

Coloring pigments Coloring pigments include, for example, titanium oxide, zinc flower, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindolin pigments, slene pigments, and perylene pigments. Examples thereof include pigments, dioxazine pigments, and diketopyrrolopyrrole pigments. In addition, other coloring components include metal flake powder such as aluminum, paste, pearl powder, graphite, MIO, mica powder and other bright pigments. Examples of the metal flake powder include aluminum flakes, nickel flakes, copper flakes, stainless steel flakes, brass flakes and chrome flakes, and examples of mica powder include pearl mica and colored pearl mica. These coloring components may be added directly to the coating material, or may be mixed with a dispersant or a dispersion resin to disperse, and the paste may be formed before being blended into the coating material. Known dispersants, dispersion resins, and dispersion methods can be used.

The amount of the solid content of the coloring component to be blended can be appropriately adjusted according to the type of pigment. For example, the range of 1 to 250 parts by mass is preferable and more preferable with respect to 100 parts by mass of the hydroxyl group-containing resin in the coloring paint. Is in the range of 2 to 150 parts by mass.

The colored paint may contain a curing agent. As the curing agent, a compound having a crosslinkable functional group capable of reacting with a hydroxyl group in a resin containing a hydroxyl group can be usually used. As such a curing agent, for example, a polyisocyanate compound, a blocked polyisocyanate compound, or the like can be preferably used. The curing agents can be used alone or in combination of two or more.

The polyisocyanate compound is a compound having two or more isocyanate groups in one molecule, and the same compound as the polyisocyanate compound (C) described later can be used. The blocked polyisocyanate compound is obtained by adding a blocking agent to the isocyanate group of the polyisocyanate compound, and can react with a hydroxyl group by dissociating the blocking agent by heating and regenerating the isocyanate group. .. The dissociation temperature of the blocking agent is usually preferably in the range of about 60 to about 140 ° C, preferably about 70 to about 120 ° C.

When a curing agent is used in the colored paint, the content thereof is 0 to 50 parts by mass, 1 to 40 parts by mass, and more particularly, with respect to 100 parts by mass of the total of the hydroxyl group-containing resin and the curing agent from the viewpoint of weather resistance. It is preferably in the range of 20 to 30 parts by mass.

Further, the colored paint may be a one-component paint or a two-component paint in which a curing agent packed in a separate container is mixed before painting.

Furthermore, colored paints include cellulose acetate butyrate, organic polymer fine particles, extender pigments, anti-settling agents, anti-sagging agents, pigment dispersants, ultraviolet absorbers, light stabilizers, antioxidants, curing catalysts and other paints. Additives and the like may be blended. Further, the colored paint may be an organic solvent type paint (including high solid and non-aqueous dispersion type) or a water-based paint. The type of organic solvent preferably does not contain toluene or xylene from the viewpoint of the influence on the human body and the environment.

Cellulose acetate butyrate is a cellulose derivative obtained by further butyrylating a partially acetylated product of cellulose, and preferably has a number average molecular weight in the range of about 10,000 to 80,000. Further, a graft copolymer of cellulose acetate butyrate and an acrylic component can also be used.

When cellulose acetate butyrate is blended, the blending amount is appropriately about 20 parts by mass or less with respect to 100 parts by mass of the resin solid content in the coating material.

Examples of the organic polymer fine particles include resin particles such as conventionally known polymer beads, finely pulverized polymers of the monomers, and gelled polymer fine particles (for example, JP-A-51-126287, Japanese Patent Application Laid-Open No. 51-126287). Kaisho 53-133233, JP-A-53-133236, JP-A-56-76447, JP-A-58-129065), and the like, and in particular, at least two radicals in the polymer. Gelled polymer fine particles (gelled polymer fine particles) obtained by emulsifying a polymerizable monomer having a polymerizable unsaturated group and other radically polymerizable unsaturated monomers in the presence of a reactive emulsifier containing an allyl group in the molecule. For example, Japanese Patent Application Laid-Open No. 3-66770) can be preferably used.

When the organic polymer fine particles are blended, the blending amount is appropriately about 5 to 30 parts by mass with respect to 100 parts by mass of the resin solid content in the coating material.

In the multi-layer coating film forming method of the present invention, a colored coating film is formed on an object to be coated. From the viewpoint of coating workability, the colored paint usually has a solid content of 10% by mass or more, particularly in the range of 15 to 45% by mass, and has a viscosity of 5 to 20 seconds, more preferably 9. It is preferable to adjust the temperature within the range of ~ 14 seconds / Iwata cup (20 ° C.).

The method of applying the colored paint is not particularly limited, and for example, it can be applied by an air spray, an airless spray, a rotary atomization coating machine, a dip coating, a brush, or the like. At the time of painting, the film thickness of the colored coating film formed by applying the colored coating film which may be electrostatically applied is usually 10 to 60 μm, particularly 20 to 50 μm, and more particularly 25 to 60 μm based on the cured coating film. It is preferably within the range of 45 μm.

On the formed colored coating film, a brilliant coating material described later and / or the coating composition of the present invention is coated on the colored coating film. The colored coating film may be cured or uncured when the brilliant coating film and / or the coating composition of the present invention is applied onto the coating film.

In the present specification, the cured coating film is a cured and dried state defined in JIS K 5600-1-1 (2004), that is, the center of the coated surface is strongly sandwiched between the thumb and the index finger, and a fingerprint is applied to the coated surface. It is a coating film in a state in which no dents are formed, the movement of the coating film is not felt, and the center of the coated surface is rapidly and repeatedly rubbed with a fingertip to leave no scratches on the coated surface. On the other hand, the uncured coating film is a state in which the coating film has not reached the cured and dried state, and also includes a touch-dried state and a semi-cured and dried state defined in JIS K 5600-1-1.

Heating is usually performed to cure the colored coating film. Examples of the heating conditions include a time of 10 to 130 minutes at a temperature of 60 to 150 ° C. In the case of uncured, preheating and air blowing can be performed before coating the clear paint in order to reduce the volatile content of the colored coating film or remove the volatile content. Preheating can usually be carried out by directly or indirectly heating the painted object in a drying oven at a temperature of 50 to 110 ° C., preferably 60 to 90 ° C. for 1 to 30 minutes. The air blow can usually be performed by blowing air heated to room temperature or a temperature of 25 ° C. to 80 ° C. on the coated surface of the object to be coated.

Bright paint The bright paint in the method for forming a multi-layer coating film of the present invention contains a hydroxyl group-containing resin and a bright pigment.

The hydroxyl group-containing resin is a resin having at least one hydroxyl group in one molecule. Examples of the hydroxyl group-containing resin include resins having a hydroxyl group, such as polyester resin, acrylic resin, polyether resin, polycarbonate resin, polyurethane resin, epoxy resin, and alkyd resin. These can be used alone or in combination of two or more.

The hydroxyl group-containing resin preferably has a hydroxyl value of 10 to 200 mg / KOH, particularly preferably 40 to 150 mg / KOH, from the viewpoint of curability and adhesiveness.

Examples of the brilliant pigment include scaly metal pigments such as aluminum, copper, nickel alloys, and stainless steel, scaly metal pigments whose surface is coated with a metal oxide, scaly metal pigments whose surface is chemically adsorbed with a coloring pigment, and surfaces. A scaly aluminum pigment having an aluminum oxide layer formed by causing an oxidation-reduction reaction, an aluminum solid-melt plate-like iron oxide pigment, a glass flake pigment, a glass flake pigment whose surface is coated with a metal or a metal oxide, and the surface is colored. Glass flake pigments with chemically adsorbed pigments, interfering mica pigments whose surface is coated with titanium dioxide, reduced mica pigments with reduced interfering mica pigments, colored mica with colored pigments chemically adsorbed on the surface or surface coated with iron oxide Pigments, graphite pigments whose surface is coated with titanium dioxide, silica flakes and alumina flake pigments whose surface is coated with titanium dioxide, disc-shaped iron oxide pigments, hologram pigments, synthetic mica pigments, cholesteric liquid crystal polymer pigments with a spiral structure, oxychloride Examples include bismuth pigments. In the present invention, among these, the use of a silver-type or colored-type bright pigment in which a translucent scaly base material is coated with a metal oxide is used to change from highlight to shade in a multi-layer coating film. It is preferable from the viewpoint of gradual change in brilliance and color tone, and among silver type or colored type, brilliant property in which titanium oxide or iron oxide is coated on a scaly base material selected from mica, artificial mica, silica or aluminum oxide. It is particularly preferred to use pigments.

It is preferable to use a bright pigment having an average particle size in the range of 5 to 25 μm from the viewpoint of finishability and graininess of the coated coating film, and more preferably 7 to 20 μm. It is in the range of 8 to 18 μm, particularly preferably in the range of 8 to 18 μm. It is preferable to use a thickness in the range of 0.05 to 0.5 μm. The particle size and thickness referred to here mean numerical values obtained by observing the bright pigment with an optical microscope or an electron microscope.

The content of the brilliant pigment is 1 to 25 parts by mass in total with respect to 100 parts by mass of the resin solid content in the paint containing the brilliant pigment from the viewpoint of the finish of the coating film obtained by painting. It is preferably in the range, more preferably in the range of 3 to 20 parts by mass, and particularly preferably in the range of 5 to 18 parts by mass.

In addition to the brilliant pigment, the brilliant paint may contain a coloring pigment for the purpose of finely adjusting the hue and brightness of the multi-layer coating film. The coloring pigment is not particularly limited, but can be appropriately selected and used from those exemplified as those that can be used in the above-mentioned coloring paint. When colored pigments are used for the colored paint and the brilliant paint, it is recommended that the chromatic pigments of the same color among the colored pigments used for each paint be used for the saturation of the multi-layer coating film. It is preferable from the point of view.

Further, the brilliant paint includes various additives such as a solvent such as water or an organic solvent, a pigment dispersant, a precipitation inhibitor, a curing catalyst, a defoaming agent, an antioxidant, and an ultraviolet absorber, and a constitution, if necessary. Pigments and the like can be appropriately blended.

The brilliant coating film can be obtained by applying the brilliant paint by a method such as electrostatic coating, air spray, or airless spray.

The film thickness of the brilliant coating film is preferably in the range of 5 to 30 μm, more preferably 13 to 25 μm based on the cured coating film, from the viewpoint of hiding the object to be coated and the smoothness of the coating film.

The brilliant coating film may be cured or uncured when the coating composition of the present invention is applied onto the coating film.

When curing the brilliant coating film, heating is usually performed. Examples of the heating conditions include a time of 5 to 130 minutes at a temperature of 60 to 150 ° C. When a clear coating film, which will be described later, is formed while the bright coating film remains uncured, before coating the coating composition of the present invention in order to reduce the volatile content of the bright coating film or remove the volatile matter. Preheating and air blowing can be performed. Preheating can usually be carried out by directly or indirectly heating the painted object in a drying oven at a temperature of 50 to 110 ° C., preferably 60 to 90 ° C. for 1 to 30 minutes. The air blow can usually be performed by blowing air heated to room temperature or a temperature of 25 ° C. to 80 ° C. on the coated surface of the object to be coated.

Formation of Clear Coating Film In the method for forming a multi-layer coating film of the present invention, the coating composition of the present invention is coated on the colored coating film or the brilliant coating film to form a clear coating film.

The coating of the coating composition of the present invention is not particularly limited and can be carried out in the same manner as the colored coating material and the brilliant coating material. For example, coating such as air spray, airless spray, rotary atomization coating and curtain coat coating. It can be done by the method. These coating methods may be electrostatically applied, if necessary. The coating amount of the coating composition of the present invention is usually preferably an amount of about 10 to 50 μm as the cured film thickness.

Further, in the coating of the coating composition of the present invention, the viscosity of the coating composition is set to a viscosity range suitable for the coating method, for example, in the rotary atomization coating, the Ford Cup No. 4 It is preferable to appropriately adjust the viscosity by using a solvent such as an organic solvent so that the viscosity range is about 15 to 40 seconds as measured by a viscometer.

In the multi-layer coating film forming method of the present invention, the clear coating film can be cured by heating the uncured clear coating film. The clear coating film can be heated by a known means, and for example, a drying furnace such as a hot air furnace, an electric furnace, or an infrared induction heating furnace can be applied. The heating temperature is preferably in the range of 60 to 150 ° C, preferably 70 to 140 ° C. The heating time is not particularly limited, but is preferably in the range of 5 to 130 minutes, more preferably 10 to 120 minutes.

In the method for forming a multi-layer coating film of the present invention, two layers of an uncured colored coating film and an uncured clear coating film can be simultaneously heated and cured. Further, in another method for forming a multi-layer coating film of the present invention, three layers of an uncured colored coating film, an uncured brilliant coating film and an uncured clear coating film can be simultaneously heated and cured. As the heating conditions, it is suitable that the heating temperature is in the range of 60 to 150 ° C., preferably 70 to 140 ° C. In particular, when the object to be coated is an organic material and its melting point is 140 ° C. or higher, the heating temperature is preferably in the range of 70 to 140 ° C., preferably 80 to 130 ° C., and the object to be coated is to be coated. When the melting point of is less than 140 ° C., the heating temperature is preferably 60 to 90 ° C., preferably 65 to 85 ° C.

The heating time is not particularly limited, but is preferably in the range of 10 to 130 minutes, more preferably 10 to 120 minutes.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples. Both "part" and "%" are based on mass.

Production Example 1 of Production of Hydroxy Group-Containing Acrylic Resin (A)
In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, thermostat and dropping pump, 40 parts of 3-methoxybutyl acetate and 1500 Swazole (trade name, Maruzen Petrochemical Co., Ltd., aromatic hydrocarbon solvent) 40 The temperature is raised to 125 ° C. with stirring while blowing nitrogen gas into the reaction vessel, and the mixture of the monomer and the polymerization initiator shown in Table 1 is placed in the reaction vessel over 3 hours using a dropping pump. Dropped at a constant rate. Then, a mixture of 0.5 part of ditert-butyl peroxide and 10 parts of butyl acetate was added dropwise over 1 hour. After completion of the dropping, the reaction was completed by aging at the same temperature for 3 hours. The obtained solution was adjusted with butyl acetate so as to have a solid content of 60%, and a solution of a hydroxyl group-containing acrylic resin (A-1) was obtained. The weight average molecular weight of the acrylic resin was about 9,000, the hydroxyl value was 121 mgKOH / g, and the glass transition temperature was 79 ° C.

Production Examples 2-5
Hydroxyl group-containing acrylic resins (A-2) to (A-5) were obtained in the same manner as in Production Example 1 except for the formulations shown in Table 1.

Silicone compound (B)
Details of the silicone compounds (B-1) to (B-6) used in the examples of the present invention are as follows.
(B-1): Weight average molecular weight 2000 to 3000, in the chemical formula (I), R ¹ is a methyl group, R ² is an ethylene group, X is a hydroxyl group, and n = 15 to 30.
(B-2): Weight average molecular weight 2000 to 3000, in the chemical formula (I), R ¹ is a methyl group, R ² is an ethylene group, X is an amino group, and n = 15 to 30.
(B-3): Weight average molecular weight 7,000 to 8,000, in the chemical formula (I), R ¹ is a methyl group, R ² is an ethylene group, X is a hydroxyl group, and n = 50 to 80.
(B-4): Weight average molecular weight 1000 to 2000, in the chemical formula (I), R ¹ is a methyl group, R ² is an ethylene group, X is a hydroxyl group, and n = 8 to 20.
(B-5): "Silicone KP-327" trade name, manufactured by Shin-Etsu Chemical Co., Ltd., phenylmethylpolysiloxane, weight average molecular weight 10,600
(B-6): "Disparon NSH8430" trade name, manufactured by Kusumoto Kasei Co., Ltd., weight average molecular weight 16000, silicone-modified acrylic
Polyisocyanate compound (C)
Details of the polyisocyanate compound (C-1) used in the examples of the present invention are as follows.
(C-1): "Sumijour N3300" trade name, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanate nurate, NCO content = 21.8%, solid content 100%
Paint composition No. 1-No. Manufacturing Example 1 of 11
15 parts (solid content) of a hydroxyl group-containing acrylic resin (A-1) solution having a solid content of 60%, 85 parts (solid content) of a hydroxyl group-containing acrylic resin (A-3) solution having a solid content of 60%, a silicone compound (B-). 1) 0.4 part (solid content), 42 parts (solid content) of polyisocyanate compound (C-1), 0.005 part of dibutyltin dilaurate, 1,8-diazabicyclo [5,4,0] -7-undecene 1 .00 parts were uniformly mixed, and the solid content was adjusted with butyl acetate so as to have a viscosity of 10 ± 1 second / Iwata cup (20 ° C.). I got 1.

Paint composition No. The equivalent ratio of the total amount of hydroxyl groups (OH) of the hydroxyl group-containing acrylic resin component in 1 to the isocyanate group (NCO) of the polyisocyanate compound is NCO / OH = 1.2.

Examples 2-7, Comparative Examples 1-4
In Example 1, the coating composition No. 1 was obtained in the same manner as in Example 1 except that the formulations of the components (A) to (C) were the formulations shown in Table 2. 2-No. I got 11. The blending amount in Table 2 indicates the blending amount of the solid content.

Production Example 6 of Production of Hydroxy Group-Containing Acrylic Resin (A-6)
40 parts of 3-methoxybutyl acetate and 1500 parts of swazole are charged in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a thermostat and a dropping pump, and the temperature rises to 100 ° C. while stirring while blowing nitrogen gas. Warm and put a mixture of 10 parts of 2-hydroxyethyl acrylate, 75 parts of methyl methacrylate, 16 parts of ethyl acrylate, 0.5 parts of acrylic acid and 1.5 parts of tert-butyl peroxide into the reaction vessel with a dropping pump. It was added dropwise at a constant rate over 3 hours. Then, a mixture of 0.5 part of ditert-butyl peroxide and 10 parts of butyl acetate was added dropwise over 1 hour. After completion of the dropping, the reaction was completed by aging at the same temperature for 3 hours. The obtained solution was adjusted with butyl acetate so as to have a solid content of 60%, and a solution of a hydroxyl group-containing acrylic resin (A-6) was obtained. The weight average molecular weight of the acrylic resin was about 35,000, the hydroxyl value was 30 mgKOH / g, and the glass transition temperature was 72 ° C.
Production Example 7 of Production of Hydroxy Group-Containing Acrylic Resin (A-7)
40 parts of 3-methoxybutyl acetate and 1500 parts of swazole are charged in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a thermostat and a dropping pump, and the temperature rises to 125 ° C while stirring while blowing nitrogen gas. Warm and drop a mixture of 30 parts styrene, 19 parts 2-hydroxyethyl acrylate, 25 parts methyl methacrylate, 25 parts normal butyl acrylate, 1 part acrylic acid and 2.0 parts ditert-butyl peroxide into the reaction vessel. The mixture was dropped at a constant rate over 3 hours using a butyl pump. Then, a mixture of 0.5 part of ditert-butyl peroxide and 10 parts of butyl acetate was added dropwise over 1 hour. After completion of the dropping, the reaction was completed by aging at the same temperature for 3 hours. The obtained solution was adjusted with butyl acetate so as to have a solid content of 60%, and a solution of a hydroxyl group-containing acrylic resin (A-7) was obtained. The weight average molecular weight of the acrylic resin was about 20,000, the hydroxyl value was 82 mgKOH / g, and the glass transition temperature was 42 ° C.

Manufacturing of colored paint Manufacturing example 8
10 parts (solid content) of a hydroxyl group-containing acrylic resin (A-6) solution having a solid content of 60%, 90 parts (solid content) of a hydroxyl group-containing acrylic resin (A-7) solution having a solid content of 60%, a polyisocyanate compound (C-) 1) 42 parts (solid content) and 80 parts of Typure R-902 + (trade name, titanium dioxide) are uniformly mixed, and the viscosity is adjusted to 10 ± 1 second / Iwata cup (20 ° C) with butyl acetate. Adjusting the solid content content, the colored paint No. I got 1.

Colored paint No. The equivalent ratio of the total amount of hydroxyl groups (OH) of the hydroxyl group-containing acrylic resin component in 1 to the isocyanate group (NCO) of the polyisocyanate compound is NCO / OH = 1.0.

Creation of object to be coated Object to be coated 1
The surface of a 100 mm × 150 mm × 3.0 mm fiber reinforced plastic (FRP) plate was degreased with isopropyl alcohol to obtain an object to be coated 1.

Object to be coated 2
The surface of a 100 mm × 150 mm × 3.0 mm acrylonitrile-butadiene-styrene plate was degreased with isopropyl alcohol to obtain an object to be coated 2.

Preparation of test plate Example 8
The colored coating material No. 1 obtained in Production Example 8 was placed on the object to be coated 1. No. 1 was coated with an air spray so as to have a film thickness of 30 μm, and set at room temperature for 10 minutes to form an uncured colored coating film. Next, on the uncured colored coating film, the coating composition No. 1 obtained in Example 1 was applied. No. 1 was coated with an air spray so that the film thickness was 35 μm, and the setting was performed at room temperature for 10 minutes to form an uncured clear coating film. Then, the uncured colored coating film and the uncured clear coating film were heated at 130 ° C. for 30 minutes and cured to obtain a test plate.

Examples 9-14, 16-22, Comparative Examples 5-12
Each test plate was obtained in the same manner as in Example 8 except that those shown in Table 3 were used as the object to be coated and the coating composition.

Example 15
The colored coating material No. 1 obtained in Production Example 8 was placed on the object to be coated 1. No. 1 was coated with an air spray so as to have a film thickness of 30 μm, and set at room temperature for 10 minutes to form an uncured colored coating film. Next, on the uncured colored coating film, a brilliant paint (“Retan PG60 202 Sun Metallic Base” trade name, manufactured by Kansai Paint Co., Ltd., a brilliant paint for plastic materials) is applied with an air spray to increase the film thickness. The coating was applied so as to have a thickness of 15 μm, and the setting was performed at room temperature for 10 minutes to form an uncured bright coating film.
Next, on the uncured brilliant coating film, the coating composition No. 1 obtained in Example 1 was applied. No. 1 was coated with an air spray so that the film thickness was 35 μm, and the setting was performed at room temperature for 10 minutes to form an uncured clear coating film. Then, the uncured colored coating film and the uncured clear coating film were heated at 130 ° C. for 30 minutes and cured to obtain a test plate.

Example 23
Each test plate was obtained in the same manner as in Example 15 except that the object to be coated 2 was used instead of the object to be coated 1.

Evaluation test Each of the obtained test plates was evaluated by the following test method. The evaluation results are shown in Table 3.

Initial water contact angle 0.4 μL of distilled water was dropped 72 hours or more after the test plate was prepared, and the contact angle (unit: °) was measured after 5 seconds. The contact angle meter used for the contact angle measurement is "CA-X150 type" (manufactured by Kyowa Interface Science Co., Ltd.).

The water contact angle test plate after the water resistance test was immersed in warm water at 90 ° C. for 96 hours, and then allowed to stand at room temperature at 25 ° C. for 24 hours three times, and then the water contact angle was measured by the same method as above. ..

Initial oleic acid contact angle 0.4 μL of oleic acid was added dropwise 72 hours or more after the test plate was prepared, and the contact angle (unit: °) was measured after 5 seconds. The contact angle meter used for the contact angle measurement is "CA-X150 type" (manufactured by Kyowa Interface Science Co., Ltd.).

The oleic acid contact angle test plate after the water resistance test was immersed in warm water at 90 ° C. for 300 hours, and then the oleic acid contact angle was measured by the same method as described above.

The contact angle retention rate is defined by the following formula.

Retention rate (%) = contact angle after water resistance test / initial contact angle x 100
A contaminant consisting of a mixture of mud, carbon black, mineral oil and clay was attached to the flannel on the stain resistance test plate and lightly rubbed against the coated surface of each test plate. After leaving this in a constant temperature and humidity chamber of 75% RH at 20 ° C. for 24 hours, the coated surface was washed with running water, and the degree of contamination of the coating film was evaluated by the following criteria based on the difference in brightness (ΔL) of the coated plate. The smaller the ΔL value, the better the stain resistance. ΔL was calculated by the following formula:
ΔL = (L value before stain resistance test)-(L value after stain resistance test)
The L value was measured using a CR400 manufactured by Konica Minolta (trade name, tristimulus value direct reading type colorimeter D65 light source 2 ° field of view diffused illumination vertical light receiving (d / 0)). The above L value is a value based on the CIE 1976 L * a * b * color system:
A is ΔL <0.2,
B is 0.2 ≦ ΔL <1,
C is 1 ≦ ΔL <2,
D is 2 ≦ ΔL.

Scratch resistance As a scratch resistance tester, a dyed product fastness friction tester (trade name "FR-II", manufactured by Suga Test Instruments Co., Ltd.) was used. The polishing powder (trade name "Dharma Cleanser", manufactured by Dharma Cleanser Honpo Co., Ltd.) was mixed with 3 g of water at a ratio of 2 g to obtain an abrasive. About 3 drops of this abrasive were attached to the flannel, the flannel was pressed by the tester terminal, and a load of 0.5 kg was applied to reciprocate 25 times. Then, the coated surface was washed with running water, air-dried, and then the coated surface was evaluated according to the following criteria.
A: No change is observed in the gloss of the coated surface, and it has excellent scratch resistance.
B: A little gloss is observed on the coated surface, and the scratch resistance is slightly poor.
C: Significant glossiness is observed on the coated surface, and scratch resistance is poor.

After immersing the adhesive test plate in water at 60 ° C. for 240 hours, use a knife to reach the substrate on the coated surface of the coated plate according to JIS K 5600-5-6 (1999) adhesiveness and cross-cut method. Using it, make 11 cuts in parallel vertically and horizontally at intervals of about 1 mm to form a goban grain, attach cellophane adhesive tape to the surface, and after the tape is rapidly peeled off, the goban grain coated surface. Was evaluated according to the following criteria.
A: No peeling of the coating film is observed.
B: Slight peeling is observed on a part of the coating film on the corner of the knife scratch.
C: Of the 100 Goban eyes, one or more are peeled off.

Claims (5)

A hydroxyl group-containing acrylic resin (A) having a glass transition temperature (Tg) in the range of 10 ° C. to 85 ° C., and a silicone compound having one or more reactive groups and having a weight average molecular weight of 500 to 10,000. A coating composition containing B) and a polyisocyanate compound (C).
The hydroxyl group-containing acrylic resin (A) has a glass transition temperature (Tg) in the range of 10 ° C. to 50 ° C., and the hydroxyl group-containing acrylic resin (A1) and the glass transition temperature (Tg) are in the range of 51 ° C. to 85 ° C. Contains acrylic resin (A2)
The initial water contact angle of the coating film formed by coating the surface to be coated so as to be 35 μm as a cured coating film is within the range of 90 to 110 °, and the initial oleic acid contact angle is 40 to 60 °. Within range
Moreover, the coating composition is characterized in that the retention rates of the water contact angle and the oleic acid contact angle after immersing the coating film in warm water at 90 ° C. for 300 hours are 90% or more of the respective initial contact angles. The coating composition according to claim 1 , wherein the silicone-based compound (B) has a polysiloxane skeleton. A colored coating material containing a hydroxyl group-containing resin and a coloring pigment is applied onto the object to be coated to form a colored coating film, and the coating composition according to claim 1 or 2 is applied onto the formed colored coating film. A method for forming a multi-layer coating film for forming a clear coating film. A colored paint containing a colored pigment is applied onto an object to be coated to form a colored coating film, and a brilliant paint containing a brilliant pigment is applied onto the formed colored coating film to form a brilliant coating film. A method for forming a multi-layer coating film, wherein the coating composition according to claim 1 or 2 is applied onto the formed glitter coating film to form a clear coating film. The method for forming a multi-layer coating film according to claim 3 or 4 , wherein the colored coating film and / or the brilliant coating film and the clear coating film are heated to a temperature of 60 ° C. to 150 ° C. and cured at the same time.