JP6746417B2 - Paint composition - Google Patents

Description

The present invention relates to a coating composition capable of forming a coating film having good finish, coating film hardness, gloss stability of a matte coating film, chemical resistance and corrosion resistance.

Recently, various coating compositions have been used for coating construction machines or industrial machines such as bulldozers, hydraulic excavators, and wheel loaders. However, construction machinery or industrial machinery has the following problems. 1. The heat capacity of the object to be coated is large and the heat in the drying oven is not sufficiently transferred, and the curability is not sufficient. 2. There are many vertical parts and the glossiness of the matte coating is not stable. Further, since construction machines or industrial machines are used outdoors, there is a problem that coating film hardness, water resistance, chemical resistance, corrosion resistance, etc. are required.

In order to achieve such a problem, conventionally, a coating composition has been developed in which two components, a base coating and a curing agent component, are mixed and used immediately before coating.

For example, in Patent Document 1, 5 to 60% by weight of a specific epoxy ester resin composition (a) and 40 to 95% by weight of an alkyd resin composition (b) having an oil length of 40 to 70% are mixed and then heated. , A resin composition (A) obtained by adding and reacting an acrylic monomer (c), and a coating composition comprising a solvent and a colorant are disclosed. The coating composition is a bulldozer. It is described that it is suitable for coating large machines for civil engineering such as power shovels and forklifts.

Patent Document 2 discloses a coating composition comprising a main agent (I) containing a resin having a hydroxyl group and a curing agent (II), wherein the main agent (I) contains an aqueous polymer polyol. In addition, a coating composition is disclosed in which the curing agent (II) contains a water-dispersible polyisocyanate and an organic solvent.

In addition, Patent Document 3 discloses a coating material containing a polyester resin (A), an acrylic resin (B), a water-dispersible polyisocyanate compound (C), and ion-exchanged amorphous silica fine particles (D). Also disclosed is a coating composition capable of forming a coating film having good storage stability and excellent coating film hardness, finish, gloss, water resistance and corrosion resistance.

However, the coating compositions described in Patent Documents 1 to 3 have problems in any of finishability, coating film hardness, gloss stability of matte coating film, chemical resistance and corrosion resistance, and improvement is required. Was there.

JP, 10-77442, A JP 2006-257141 A JP, 2007-284480, A

The problem to be solved by the present invention is to provide a coating composition capable of forming a coating film having good finish, coating film hardness, gloss stability of a matte coating film, chemical resistance and corrosion resistance.

As a result of diligent studies, the inventors have found that a hydroxyl group-containing resin (a), barium sulfate (a1) having an average particle diameter of 0.01 to 2.0 μm, talc (a2) having an average particle diameter of 10 μm or more, and organic resin particles ( The inventors have found that the solution of the above problems can be achieved by a coating composition containing a3), a color pigment (a4), and a polyisocyanate compound (b), and completed the present invention.

That is, the present invention is
1. Hydroxyl group-containing resin (a), barium sulfate (a1) having an average particle diameter of 0.01 to 2.0 μm, talc (a2) having an average particle diameter of 10 μm or more, organic resin particles (a3) and color pigment (a4), and A coating composition containing a polyisocyanate compound (b), wherein 1 to 130 parts by mass of barium sulfate (a1) and talc (a2) are based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). 1 to 50 parts by mass, the organic resin particles (a3) to 0.1 to 20 parts by mass, the color pigment (a4) to 1 to 100 parts by mass, and the polyisocyanate compound (b) to 10 to 60 parts by mass. Stuff,
2. The coating composition according to item 1, which contains 0.1 to 10 parts by mass of the silane coupling agent (b1) based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a).
3. Item 1 or 2 containing 0.1 to 10 parts by mass of a stain resistant agent (b2) represented by the following formula (1), based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). The coating composition described,
_{^{(R 1) n -Si- (OR}} 2) 4-n ··· Equation (1)
(In the formula (1), R ¹ is an alkyl group having 1 to 18 carbon atoms or a phenyl group which may be substituted with an epoxy group or a mercapto group, and R ² is an alkyl group having 1 to 6 carbon atoms. , N is 0 or 1)
4. The present invention relates to a construction machine or an industrial machine, which has a cured coating film of the coating composition according to any one of items 1 to 3 on an object to be coated.

The coating composition of the present invention can form a coating film having good finish, coating hardness, gloss stability of matte coating, chemical resistance and anticorrosion.

Specifically, the coating composition of the present invention is 1. 1. Even an object having a large heat capacity can be sufficiently cured at a low temperature in a short time. A coated article having a cured coating film of the coating composition can obtain a matte coating film having a 60-degree specular gloss of 10 to 70, preferably 25 to 65, which is excellent in gloss stability and has no gloss unevenness. 2. There is little fluctuation in glossiness due to the painted part (vertical part) and baking temperature. Since it has excellent chemical resistance and anticorrosion property, it is possible to obtain the effect of the invention that it is also useful for outdoor use. The coating composition of the present invention can be suitably used, for example, as a coating for construction machinery or industrial machinery.

The present invention provides a hydroxyl group-containing resin (a), barium sulfate (a1) having an average particle size of 0.01 to 2.0 μm, talc (a2) having an average particle size of 10 μm or more, organic resin particles (a3), and a color pigment ( a4), and a coating composition containing a predetermined amount of the polyisocyanate compound (b). The details will be described below.

Hydroxyl group-containing resin (a):
The hydroxyl group-containing resin (a) is a resin having at least one hydroxyl group in one molecule. Examples of the hydroxyl group-containing resin (a) include resins having a hydroxyl group, such as polyester resin, acrylic resin, polycarbonate resin, polyurethane resin, epoxy resin and alkyd resin. These may be used alone or in combination of two or more. Among them, the hydroxyl group-containing resin (a) is preferably a hydroxyl group-containing acrylic resin from the viewpoint of coating film hardness and weather resistance.

The hydroxyl group-containing acrylic resin is usually a copolymer of a hydroxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer. The method for obtaining the copolymer includes a method known per se, such as a solution polymerization method in an organic solvent and an emulsion polymerization method in water.

The hydroxyl group-containing polymerizable unsaturated monomer is a compound having at least one hydroxyl group and at least one polymerizable unsaturated bond in one molecule, and specific examples thereof include 2-hydroxyethyl (meth)acrylate and 2-hydroxy. Propyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth ) Acrylate, 8-hydroxyoctyl (meth)acrylate or other (meth)acrylic acid and a monoester compound of a dihydric alcohol having 2 to 8 (preferably 2 to 4) carbon atoms; the (meth)acrylic acid and carbon number Ε-caprolactone modified product of monoester with 2-8 dihydric alcohol; N-hydroxymethyl(meth)acrylamide; allyl alcohol, and further (meth)acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end, etc. Can be mentioned. In the present invention, the polymerizable unsaturated monomer having an ultraviolet absorbing functional group such as 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone described below is a hydroxyl group-containing polymerizable unsaturated monomer. Rather, it is included in other polymerizable unsaturated monomers copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer.

Other polymerizable unsaturated monomers copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl( (Meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth) Acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, "isostearyl acrylate" (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), cyclohexyl (meth)acrylate, methyl Alkyl or cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate; polymerizable unsaturated monomers having an isobornyl group such as isobornyl (meth)acrylate; adamantyl Polymerizable unsaturated monomer having adamantyl group such as (meth)acrylate; vinyl aromatic compound such as styrene, α-methylstyrene, vinyltoluene; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane , Γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane and other polymerizable unsaturated monomers having an alkoxysilyl group; perfluorobutylethyl (meth)acrylate, perfluorooctylethyl Perfluoroalkyl (meth)acrylates such as (meth)acrylates; polymerizable unsaturated monomers having fluorinated alkyl groups such as fluoroolefins; polymerizable unsaturated monomers having photopolymerizable functional groups such as maleimide groups; N-vinyl Vinyl compounds such as pyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate and vinyl acetate; (meth) acrylic acid, maleic acid, crotonic acid, carboxyl group-containing polymerizable unsaturated monomers such as β-carboxyethyl acrylate; (meth) Acrylation with acrylonitrile, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, glycidyl (meth)acrylate Nitrogen-containing polymerizable unsaturated monomer such as adduct with compound; Polymerization having two or more polymerizable unsaturated groups such as allyl (meth)acrylate and 1,6-hexanedioldi (meth)acrylate in one molecule Unsaturated monomer; glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexyl Epoxy group-containing polymerizable unsaturated monomers such as propyl (meth)acrylate and allyl glycidyl ether; (meth)acrylate having a polyoxyethylene chain whose molecule end is an alkoxy group; 2-acrylamido-2-methylpropanesulfonic acid, allyl Sulfonic acid, styrenesulfonic acid sodium salt, sulfoethyl methacrylate and its sodium salt, polymerizable unsaturated monomers having a sulfonic acid group such as ammonium salt; 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2- Acryloyloxypropyl acid phosphate, 2-methacryloyloxypropyl acid phosphate and other polymerizable unsaturated monomers having a phosphoric acid group; 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2-hydroxy-4 -(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-acryloyloxy 2-(meth)acryloyl, a polymerizable unsaturated monomer having an ultraviolet absorbing functional group such as 2-hydroxypropoxy)benzophenone and 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole; Oxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloylamino-2, 2,6,6-Tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4- (Meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-croto Noyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6- UV stable polymerizable unsaturated monomers such as tetramethylpiperidine; acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrene, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl methyl Examples thereof include polymerizable unsaturated monomer compounds having a carbonyl group such as ketone, vinyl ethyl ketone, and vinyl butyl ketone), and these can be used alone or in combination of two or more kinds.

The hydroxyl group-containing resin (a) preferably has a hydroxyl value in the range of 30 to 300 mgKOH/g, particularly 40 to 250 mgKOH/g, from the viewpoint of coating film hardness and corrosion resistance.

From the viewpoint of reactivity with the polyisocyanate compound (b), the hydroxyl group-containing resin (a) preferably has an acid value of 20 mgKOH/g or less, particularly 1 to 15 mgKOH/g.

The hydroxyl group-containing resin (a) preferably has a weight average molecular weight in the range of generally 3,000 to 100,000, particularly 3,000 to 50,000, and particularly 4,000 to 30,000.

The "weight average molecular weight" in the specification is a value calculated based on the molecular weight of standard polystyrene from a chromatogram measured by gel permeation chromatography according to the method described in JIS K 0124-2011.

For the gel permeation chromatograph, "HLC8120GPC" (manufactured by Tosoh Corporation) was used. As the column, four columns of "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL", and "TSKgel G-2000HXL" (both manufactured by Tosoh Corporation, trade names) were used, and mobile phase: tetrahydrofuran Measurement temperature: 40° C., flow rate: 1 ml/min, detector: RI.

However, in the present invention, the hydroxyl group-containing resin corresponding to the organic resin particles (a3) described later is excluded from the “hydroxyl group-containing resin (a)”.

Barium sulfate (a1):
The coating composition of the present invention contains barium sulfate (a1) having an average particle diameter of 0.01 to 2.0 μm, preferably 0.02 to 1.0 μm.

Examples of commercially available barium sulfate (a1) include Varifine BF-20 (manufactured by Sakai Chemical Industry Co., Ltd., trade name, average particle size 0.03 μm), SS-50 (produced by Sakai Chemical Industry Co., Ltd., trade name, Average particle diameter 0.5 μm), barium sulfate 100 (manufactured by Sakai Chemical Industry Co., Ltd., trade name, average particle diameter 0.6 μm), precipitated barium sulfate PS-07 (Guangxi Xiangzh, trade name, average particle diameter 0.74 μm) , Precipitated barium sulfate Blanc Fix HD80 (Solvay Varice Derivati SpA, trade name, average particle size 0.8 μm), barium sulfate HF, Fukashu Kashinka Co., Ltd., trade name, average particle size 0.9 μm.

In addition, the average particle diameter in this specification is a value obtained by particle size distribution measurement by a dynamic light scattering method, more specifically, a value measured using UPA-EX250 (trade name, manufactured by Nikkiso Co., Ltd.). means.

The barium sulfate (a1) content is 1 to 130 parts by mass, preferably 20 to 110 parts by mass, based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). It is possible to obtain a coating film having excellent coating hardness, gloss stability of a matte coating film, chemical resistance and corrosion resistance.

Talc (a2):
The coating composition of the present invention contains talc (a2) having an average particle size of 10 μm or more, preferably 11 to 20 μm.

The above-mentioned talc (a2) is a scaly particle having a layered structure, is a hydrous magnesium silicate in terms of chemical composition, is generally represented by the chemical formula 4SiO ₂ ·3MgO·2H ₂ O, and is usually SiO 2. ₂ is 56 to 65 mass %, MgO is 28 to 35 mass %, and H ₂ O is about 5 mass %.

Other minor _Fe 2 _{O 3} as a component from 0.03 to 1.2 wt%, _Al 2 _{O 3} is 0.05 to 1.5 mass%, CaO is 0.05 to 1.2 _{wt%, K} 2 O Is 0.2 mass% or less, Na ₂ O is 0.2 mass% or less, and the like, the specific gravity is about 2.7, and the Mohs hardness is 1.

Commercial products of talc (a2) are, for example, talc GTA (Kyowa Mining Co., Ltd., trade name, average particle size 10 μm), talc CTA-2 (Kihara Kasei Co., Ltd., trade name, average particle size 11 μm, S talc). (Nippon Taishi Smelting Co., Ltd., trade name, average particle size 11 μm), TALCAN POWDER PK-S (Hayashi Kasei Co., Ltd., trade name, average particle size 11 μm), Talc No. 1 (Takehara Chemical Industry Co., Ltd. trade name, Average particle diameter 11 μm), Talc No. 2 (Takehara Chemical Industry Co., Ltd., trade name, average particle diameter 11 μm), Talc T-1 (Fuji Talc Industry Co., Ltd., trade name, average particle diameter 11 μm), Talc SW-D ( Asada Flour Milling Co., Ltd., trade name, average particle size 12 μm, Talc SSS (Nippon Talc Co., Ltd., trade name, average particle size 12 μm), Talc DNB (Nippon Talc Co., Ltd., trade name, average particle size 12 μm), PS Talc (Takehara Chemical Industry Co., Ltd., trade name, average particle size 14 μm), Talc MA (Nippon Talc Co., Ltd., trade name, average particle size 14 μm), Talc M (Nippon Talc Co., Ltd., trade name, average particle size 16 μm), TTK Talc (Takehara Chemical Industry Co., Ltd., trade name, average particle size 17 μm), T Talc (Takehara Chemical Industry Co., Ltd., trade name, average particle diameter 17 μm), Crown Talc 3S (Matsumura Sangyo Co., Ltd. trade name, average particle) Diameter 18 μm) and the like.

The blending amount of talc (a2) in the coating composition of the present invention is in the range of 1 to 50 parts by mass, preferably 10 to 40 parts by mass with respect to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). It is desirable in order to obtain a coating having excellent coating hardness, matte coating gloss stability and chemical resistance.

Organic resin particles (a3):
The coating composition of the present invention contains organic resin particles (a3). The organic resin particles (a3) have an average particle size of 6 to 22 μm, preferably 8 to 20 μm. Examples of the organic resin particles (a3) include acrylic resin particles.

Furthermore, by mixing two kinds of organic resin particles (a3) having an average particle size of 6 to 15 μm and an average particle size of 16 to 22 μm, it is possible to further improve the gloss stability of the matte coating film.

In addition, as a commercially available product of the organic resin particles (a3), specifically, Techpolymer MBX-12 (manufactured by Sekisui Plastics Industry Co., Ltd., average particle diameter 12 μm, acrylic resin), Techpolymer MBX-15 (Sekisui Plastics Industry Co., Ltd.) Co., Ltd., average particle size 15 μm, acrylic resin), Techpolymer MBX-20 (manufactured by Sekisui Plastics Co., Ltd., average particle size 20 μm, acrylic resin), Techpolymer MB30X-20 (manufactured by Sekisui Plastics Co., Ltd., average particle size) 20 μm, acrylic resin), Techpolymer BM30X-20 (manufactured by Sekisui Plastics Co., Ltd., average particle size 20 μm, acrylic resin), Diasphere MPB-X10 (manufactured by KOLON, trade name, average particle size 10 μm, acrylic resin). To be

The mixing ratio of the organic resin particles (a3) is 0.1 to 20 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). However, it is also desirable in order to obtain a coating film having excellent gloss stability of the matte coating film.

By adding the above-mentioned barium sulfate (a1), talc (a2) and organic resin particles (a3), finish, coating hardness, gloss stability of matte coating, chemical resistance and corrosion resistance A coating film having an excellent balance can be obtained.

Color pigment (a4)
A color pigment (a4) can be added for the purpose of adjusting the hue and lightness of the cured coating film of the coating composition of the present invention. The color pigment (a4) is not particularly limited, but specifically, white color pigments such as titanium oxide; black color pigments such as carbon black, graphite (iron) and iron black (iron black). Blue pigments such as navy blue, ultramarine blue, cobalt blue, copper phthalocyanine blue, and indanthrone blue; synthetic yellow iron oxide, transparent red iron oxide (yellow), bismuth vanadate, titanium yellow, monoazo yellow, disazo yellow. , Yellow color pigments such as isoindolinone yellow, metal complex salt azo yellow, quinophthalone yellow, and benzimidazolone yellow; red iron oxide, transparent red iron oxide (red), monoazo red, monoazo red, unsubstituted quinacridone red, azo lake (Mn salt) , Quinacridone magenta, ansanthuron orange, dianthraquinonyl red, perylene maroon, perylene red, diketopyrrolopyrrole chrome vermilion, etc. red color pigments; chlorinated phthalocyanine green, brominated phthalocyanine green, etc. Pigments: Other coloring pigments such as pyrazolone orange, benzimidazolone orange, dioxazine violet, and perylene violet are mentioned. These may be used alone or in combination of two or more.

The mixing ratio of the color pigment (a4) in the coating composition of the present invention is in the range of 1 to 100 parts by mass, preferably 10 to 60 parts by mass, based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). That is, it is possible to obtain a coating film excellent in finish, gloss stability of a matte coating film, and anticorrosion property.

Polyisocyanate compound (b):
The polyisocyanate compound (b) in the coating composition of the present invention is a compound having two or more free isocyanate groups in one molecule, and the isocyanate groups are not blocked with a blocking agent.

Specifically, those conventionally used for polyurethane production can be used. Such polyisocyanates include aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, araliphatic polyisocyanate compounds, aromatic polyisocyanate compounds and their crude products, modified products of these polyisocyanate compounds (urethane groups, Carbodiimide group, allophanate group, urea group, buret group, uretdione group, uretoimine group, isocyanurate group, oxazolidone group-containing modified product, etc.) and mixtures of two or more thereof.

Specific examples of the aliphatic polyisocyanate compound include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate. , Lysine diisocyanate, 2,6-diisocyanatomethylcaproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexano Ato etc. are mentioned.

Specific examples of the alicyclic polyisocyanate compound include isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4′-diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis( 2-isocyanatoethyl)-4-cyclohexene-1,2-dicarboxylate, 2,5- and/or 2,6-norbornane diisocyanate and the like can be mentioned.

Specific examples of the araliphatic polyisocyanate compound include m- or p-xylylene diisocyanate (XDI), α,α,α′,α′-tetramethylxylylene diisocyanate (TMXDI), and the like.

Specific examples of the aromatic polyisocyanate compound include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4'- or 4 ,4'-biphenylmethane diisocyanate (MDI), 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'- Diisocyanatodiphenylmethane, crude MDI, 1,5-naphthylene diisocyanate, 4,4′,4″-triphenylmethane triisocyanate, m- or p-isocyanatophenylsulfonyl isocyanate and the like can be mentioned.

The modified polyisocyanate compound (b) may be modified MDI (urethane-modified MDI, carbodiimide-modified MDI, trihydrocarbyl phosphate-modified MDI), urethane-modified TDI, biuret-modified HDI, isocyanurate-modified HDI, isocyanurate-modified IPDI. And a mixture of two or more kinds thereof (for example, combined use of modified MDI and urethane modified TDI (isocyanate group-containing prepolymer)). Isocyanurate-modified HDI and the like are preferable.

Preferred as the above polyisocyanate compound (b) are aliphatic polyisocyanate compounds and alicyclic polyisocyanate compounds from the viewpoint of chemical resistance and corrosion resistance. The number average molecular weight of the polyisocyanate compound (b) is preferably 3,000 or less, and particularly preferably in the range of 100 to 1,500.

Examples of commercially available products of such polyisocyanate compound (b) include Bayhydur TP-LS2550, Sumidur N3300 (above, manufactured by Sumika Bayer Urethane Co., Ltd.), TPA100 (manufactured by Asahi Kasei Chemicals Co., Ltd.), BASONAT (Basonato). ) HI100 (manufactured by BASF Corporation) and the like.

The amount of the polyisocyanate compound (b) is 10 to 60 parts by mass, preferably 15 to 45 parts by mass, based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a), the coating film hardness is It is preferable in terms of chemical resistance and corrosion resistance.

Silane coupling agent (b1)
The coating composition of the present invention may contain a silane coupling agent (b1), if necessary.

Examples of the silane coupling agent (b1) include methacryl group-containing silane coupling agents such as 3-methacryloxypropylmethyldimethoxysilane and 3-methacryloxypropyltrimethoxysilane; 3-aminopropyltrimethoxysilane, 3- Aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(aminoethyl)-3-aminopropyltrimethoxysilane Amino group-containing silane coupling agent such as ethoxysilane; 3-glycidoxypropylmethyldimethoxyxysilane, 3-glycidoxypropyltrimethoxyxysilane, 3-glycidoxypropyltriethoxyxysilane, 2-(3, Epoxy group-containing silane coupling agent such as 4-epoxycyclohexyl)ethyltrimethoxysilane; Isocyanate group-containing silane coupling agent such as 3-isocyanatopropyltriethoxysilane; Isocyanurate such as tris-(trimethoxysilylpropyl)isocyanurate Group-containing silane coupling agent; vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane. Among these silane coupling agents, epoxy group-containing silane coupling agents such as 3-glycidoxypropylmethyldimethoxysisilane and 3-glycidoxypropyltriethoxyxysisilane are preferable from the viewpoint of improving corrosion resistance. These silane coupling agents (b1) may be used alone or in combination of two or more.

In addition, as a commercial item of a silane coupling agent (b1), KBM-402, KBM-403, KBM-502, KBM-503, KBM-603, KBM-907, KBM-9659, KBE-903, KBE-602, KBE-603 (above, Shin-Etsu Silicone Co., Ltd. brand name) etc. are mentioned.

The blending amount of the silane coupling agent (b1) is 0.1 to 10 parts by mass, preferably 0.2 to 8 parts by mass, based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). It is desirable to contain the compound in an amount of part by mass in order to improve finish properties and anticorrosion properties.

Antifouling agent (b2)
The coating composition of the present invention may contain an organosilicate compound represented by the following formula (1) or a condensate thereof as a stain-proofing agent (b2), if necessary.

_{^{(R 1) n -Si- (OR}} 2) 4-n ··· Equation (1)
(In formula (1), R ¹ is an alkyl group having 1 to 18 carbon atoms which may be substituted with a mercapto group or a phenyl group, R ² is an alkyl group having 1 to 6 carbon atoms, and n is 0 or 1)
The stain-proofing agent (b2) is used so that the stain-resistant property can be efficiently maintained on the surface of the substrate after coating, and from the viewpoint of this effect, the organosilicate condensate is more preferable.

Specific examples of R ¹ in the above general formula include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, pentyl, hexyl, heptyl, n-octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, Tetradecyl, hexadecyl, octadecyl, glycidyl, methylglycidyl (2-methylglycidyl), mercaptomethyl, 2-mercaptoethyl, 2-mercaptopropyl, 3-mercaptopropyl, 4-mercaptobutyl, phenyl, p-mercaptophenyl group and the like. be able to.

Specific examples of organosilicates and/or organosilicates of condensates thereof include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraisobutoxysilane, and other tetrafunctional silanes; Methoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, methyltrin-butoxysilane, methyltriisobutoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, phenyltriisopropoxy Silane, phenyltri-n-butoxysilane, phenyltriisobutoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, lauryltrimethoxysilane, lauryltriethoxysilane, mercaptomethyltrimethoxysilane, mercaptoethyltrimethoxysilane, mercaptomethyltrimethoxysilane Examples include trifunctional silanes such as ethoxysilane, mercaptoethyltriethoxysilane, mercaptopropyltrimethoxysilane, and mercaptopropyltriethoxysilane. Examples of the organosilicate condensate include condensates of one or a combination of two or more of these tetrafunctional or trifunctional silanes.

Commercially available products of condensates of organosilicates include, for example, MKC silicate MS51, MKC silicate MS56, MKC silicate MS57, MKC silicate MS56S, MKC silicate MS56SB5, MKC silicate MS58B15, MKC silicate MS58B30, MKC silicate ES40, MKC silicate M40, MKC silicate M40, MKC silicate M40, MKC silicate M40, MKC silicate M40, MKC silicate M40, and MKC silicate M40. Silicate BTS (all manufactured by Mitsubishi Chemical Co., Ltd., trade name), methyl silicate 51, ethyl silicate 40, ethyl silicate 40T, ethyl silicate 48 (all manufactured by Colcoat Co., Ltd., trade names), KR500, KR9218, Examples include X-41-1805, X-41-1810, X-41-1818, X-41-1053, X-41-1056 (all of which are manufactured by Shin-Etsu Chemical Co., Ltd., trade names). ..

In the coating composition of the present invention, the stain resistant agent (b2) may be used alone or in combination of two or more kinds. The organosilicate represented by the above general formula and/or its condensate has a methoxy group and an alkoxy group having 2 to 6 carbon atoms as an OR ² group, and a methoxy group/an alkoxy group having 2 to 6 carbon atoms. It is preferable from the viewpoint of storage stability that the ratio of the number of is within the range of 95/5 to 30/70.

In the coating composition of the present invention, the amount of the stain-proofing agent (b2) blended is 0.1 to 10 parts by mass, preferably 0.1% by mass, based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). The amount of 2 to 8 parts by mass is preferable from the viewpoint of finishability and stain resistance.

Other Ingredients In the coating composition of the present invention, if necessary, extender pigments such as clay, mica and calcium carbonate; zinc oxide, fine silica powder, bismuth hydroxide, basic bismuth carbonate, nitric acid. Antirust pigments such as bismuth, bismuth silicate, zinc phosphate, aluminum phosphate, zinc molybdate, calcium molybdate; UV absorbers, light stabilizers, defoamers, pigment dispersants, surface conditioners, surfactants , Curing catalysts, thickeners, preservatives, antifreezing agents, other matting agents, other resins, and the like can be added.

Production of coating composition of the present invention The coating composition of the present invention is preferably a two-pack type coating composition obtained by mixing the base coating (I) and the curing agent component (II). The two-pack type coating composition can be produced, for example, by the following steps 1 to 3.

Step 1:
This is a process of manufacturing the base paint (I). The base paint (I) includes a hydroxyl group-containing resin (a), barium sulfate (a1) having an average particle size of 0.01 to 2.0 μm, talc (a2) having an average particle size of 10 μm or more, organic resin particles (a3), and It can be manufactured by mixing the color pigment (a4).

The base paint (I) may include a color pigment, a rust preventive pigment, an extender pigment other than the above, an ultraviolet absorber, a light stabilizer, a defoaming agent, a pigment dispersant, a surface modifier, a surfactant, if necessary. A curing catalyst, a thickener, a preservative, an antifreezing agent, other matting agents, other resins, etc. can be added.

Further, the above base paint (I) has good storage stability as compared with the conventional base paint even if the solid content concentration is 65 to 80% by mass, preferably 68 to 75% by mass.

Process 2:
This is a step of producing the curing agent component (II). The curing agent component (II) is obtained by mixing the polyisocyanate compound (b) with the silane coupling agent (b1), the stain resistant agent (b2), a surfactant, a surface conditioner, etc., if necessary. Can be manufactured.

Process 3:
It is a step of producing the coating composition of the present invention. The coating composition can be obtained by adding the curing agent component (II) to the base coating (I). The coating composition of the present invention also includes a state in which the base coating (I) and the curing agent component (II) are not mixed and a state in which the base coating (I) and the curing agent component (II) are mixed. Be done.

Coating film forming method The coating film forming method using the coating composition of the present invention includes, for example, a step of coating the coating composition on the article to be coated with or without a primer coating, The method includes a step of baking and drying the coating object coated with the coating composition at 50 to 160° C. for 10 to 120 minutes.

Examples of the article to be coated include cold rolled steel sheet, black skin steel sheet, galvannealed steel sheet, galvanized steel sheet, aluminum and the like. Furthermore, if necessary, shot blasting, surface adjustment, chemical conversion treatment, etc. can be performed. Further, low-temperature curing (50 to 100° C.) is possible for an object to be coated that has a large heat capacity and cannot sufficiently heat the coating film.

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

Production Example 1 Production of Acrylic Resin Solution 113 parts of a mixed solvent (xylene/n-butyl alcohol=80/20) were charged into a reaction vessel and kept at 80° C., and the following “mixture” was added dropwise over 4 hours. Then, 8 parts of di-tert-butyl hydroperoxide was added, the mixture was kept at 80° C. for 3 hours to carry out the reaction, and further adjusted with a mixed solvent (xylene/n-butyl alcohol=80/20) to give a solid. A 60% by weight acrylic resin solution was produced. The resulting acrylic resin solution had a hydroxyl value of 94.9 mgKOH/g, an acid value of 3.9 mgKOH/g, and a weight average molecular weight of 11,000.

"mixture"
Styrene 41.6 parts n-Butyl acrylate 6.9 parts Isobutyl methacrylate 19 parts Praxel FM-3 (Note 1) 15 parts 2-hydroxyethyl methacrylate 17 parts Acrylic acid 0.5 parts (Note 1) Praxel FM-3: Daicel Chemical Industry Co., Ltd., trade name, ε-caprolactone modified vinyl monomer of 2-hydroxyethyl acrylate.

Manufacturing Example 1 of coating composition Coating composition No. 1
By the following steps 1 to 3, the coating composition No. Got 1.

Step 1 20 parts (solid content) of the acrylic resin solution obtained in Production Example 1, 40 parts (solid content) of Varifine BF-20 (Note 2), 30 parts (solid content) of Talc MA (Note 6), 6 parts (solid content) of Taipaque CR-95 (Note 10), 0.5 parts of FASTONGN BLUE RSK (Note 11) and ethyl acetate were added in appropriate amounts and dispersed for 12 hours with a ball mill to obtain a pigment dispersion paste.

Step 2 To 80 parts (solid content) of the acrylic resin solution obtained in Production Example 1 was added the pigment dispersion paste obtained in the above Step 1 and stirred, and then 8 parts of Techpolymer MBX-8 (Note 15) was added. Then, ethyl acetate was added to adjust the solid content to obtain a base paint having a solid content of 65 mass %.

Step 3 50 parts (solid content) of Sumidule N3300 (Note 18) was added to the pigment-dispersed paste obtained in the above Step 1, and the solid content was adjusted with ethyl acetate to obtain a coating material having a solid content of 60% by mass. Composition No. Got 1.

Examples 2-31 Coating composition No. 2 to No. 31
Coating composition No. 1 was obtained in the same manner as in Example 1 except that the contents of the formulations in Tables 1 and 2 were used. 2 to No. I got 31.

Comparative Examples 1 to 15 Coating composition No. 32-No. 46
The coating composition No. 1 was obtained in the same manner as in Example 1 except that the formulation contents shown in Table 3 were used. 32-No. I got 46. Further, the results obtained by the test according to the production of the test plate are also shown.

(Note 2) Varifine BF-20: manufactured by Sakai Chemical Industry Co., Ltd., trade name, barium sulfate having an average particle size of 0.03 μm (Note 3) Precipitable barium sulfate PS-07: manufactured by Guangxi Xiangzh, trade name, average particles Barium sulfate (Note 4) SPARWITE W-5HB having a diameter of 0.74 μm: manufactured by Wilber Ellis, trade name, average particle diameter 1.6 μm
(Note 5) LAKABAR SF: manufactured by LAKAVISUTH (trade name), trade name, barium sulfate powder, average particle size 14 μmg
(Note 6) Talc MA: manufactured by Nippon Talc Co., Ltd., trade name, Talc, 14 μm
(Note 7) TTK talc: Takehara Chemical Co., Ltd., trade name, talc, average particle size 17 μm
(Note 8) T talc: Takehara Chemical Co., Ltd., trade name, talc, average particle size 9 μm
(Note 9) Hirac: Takehara Chemical Co., Ltd., trade name, talc, average particle size 7 μm
(Note 10) Taipaque CR-95: manufactured by Ishihara Sangyo Co., Ltd., trade name, titanium dioxide (Note 11) FASTONGN BLUE RSK: manufactured by DIC, trade name, copper phthalocyanine blue (Note 12) Sylysia 445: manufactured by Fuji Silysia Chemical Ltd., Trade name, fine silica powder, delusterant (Note 13) Neolite SA-200: Takehara Chemical Industry Co., Ltd., trade name, calcium carbonate, oil absorption 32 ml/100 g
(Note 14) Techpolymer MBX-8: Sekisui Plastics Co., Ltd., acrylic resin fine particles, average particle diameter 8 μm
(Note 15) Techpolymer MBX-15: Sekisui Plastics Co., Ltd., acrylic resin fine particles, average particle diameter 15 μm
(Note 16) Techpolymer MBX-20: manufactured by Sekisui Plastics Co., Ltd., trade name, acrylic resin fine particles, average particle diameter 20 μm
(Note 17) Techpolymer MB30X-20: Sekisui Plastics Co., Ltd., acrylic resin fine particles, average particle diameter 20 μm
(Note 18) Sumidur N3300: manufactured by Sumika Bayer Urethane Co., Ltd., trade name, hexamethylene diisocyanate isocyanurate, NCO equivalent 193
(Note 19) BASONAT HI100: manufactured by BASF, trade name, hexamethylene diisocyanate isocyanurate, NCO equivalent 190
(Note 20) KBM-403: Shin-Etsu Chemical Co., Ltd., trade name, epoxy group-containing silane coupling agent (Note 21) KBM-603: Shin-Etsu Chemical Co., Ltd., trade name, amino group-containing silane coupling agent (Note 22) MKC Silicate MS56S: Mitsubishi Chemical Co., Ltd., trade name, methyl esterified silicate which is a condensate of tetramethoxysilane.
(Note 23) MKC silicate MS58B30: manufactured by Mitsubishi Chemical Corporation, trade name, methyl/butyl mixed esterified silicate that is a condensate of tetraalkoxysilane, and the ratio of the number of methyl/butyl is 70/30.

In addition, regarding the production and performance evaluation of the test plate, the test plate was prepared according to the following, and the results obtained by the test are shown in Tables 1 to 3.

Preparation of test plate A cold-rolled steel sheet (100 mm x 300 mm x 2.0 mm) that had been subjected to a zinc phosphate chemical conversion treatment was used for the coating composition No. 1 obtained in the above Examples and Comparative Examples. 1-No. 48 was spray-coated to a dry film thickness of 50 μm. Then, each test plate was obtained by heating and drying at 95° C. for 20 minutes using an electric hot air dryer.

Performance evaluation (Note 24) Storage stability of base paint:
Each base paint was put in a 250 ml glass container, stored at 20° C. for 4 hours in the dark, and the condition was checked.

◎ indicates that neither gelation, phase separation nor sedimentation of the coating composition was observed. ○ indicates that gelation or phase separation of the coating composition was not observed, and sedimentation was slightly observed, but it returned to the original with gentle stirring. △ Indicates that at least one of gelation and phase separation of the coating composition is slightly observed. × indicates that at least one of gelation and phase separation of the coating composition is remarkable.

(Note 25) Finishability: The appearance of the coated surface was visually evaluated for the test plate that had been heated and dried at 95° C. for 20 minutes.

○ indicates that the smoothness is good and there is no problem. △ indicates that the finish such as waviness, glossiness and dusty skin is slightly deteriorated.
In the case of x, the finishability of waviness, glossiness, dusty skin, etc. is greatly reduced.

(Note 26) Coating hardness: A test plate that has been heated and dried at 95° C. for 20 minutes is applied with a pencil lead at an angle of about 45° with respect to the test coated plate surface according to JIS K 5600-5-4. While being pressed against the surface of the test coated plate so strongly that it would not break, it was moved forward about 10 mm at a uniform speed. The hardness of the hardest pencil that did not break the coating film was defined as the pencil hardness.

(Note 27) Gloss stability of matte coating: Electrodeposition coating is applied to a cold-rolled steel sheet (70 mm x 300 mm x 2.0 mm) that has been subjected to zinc phosphate chemical conversion treatment so that the dry film thickness is 20 μm, and baking is performed. It was dried to obtain an electrodeposition coated plate.

Next, each coating composition obtained in the above Examples and Comparative Examples was spray-coated with the surface of the coated object vertical so that the dry film thickness was 50 μm, and the gloss of the coated plate was baked at 60° C. for 20 minutes. Then, the “gloss degree difference (Δ)” of the gloss degree of the coated plate baked at 160° C. for 20 minutes was obtained.

The glossiness of each coating film was measured according to JIS K 5600-4-7 (1999) "60 degree specular glossiness". The average value was obtained by measuring n=10 at intervals of about 2.5 cm in the direction and evaluated according to the following criteria.

◎, the gloss difference (△) is within ±2,
◯ indicates that the absolute value of the gloss difference (△) exceeds 2 and is within 5;
Δ indicates that the absolute value of the gloss difference (Δ) exceeds 5 and is within 10;
In the case of x, the absolute value of the glossiness difference (Δ) exceeds 10.

(Note 28) Chemical resistance: A test plate heated and dried at 95° C. for 20 minutes was immersed in deionized water at 40° C. for 240 hours and then pulled up, according to JIS K 5600-5-6 (1999) cross-cut tape method. Then, a knife is used to reach the base material on the coating surface of the coated plate, and 11 cuts are made in each of the vertical and horizontal directions at intervals of about 2 mm to form goggles, and cellophane (registered trademark) is formed on the surface. ) Adhesive tape was applied, and the burdock surface after the tape was rapidly peeled off was evaluated according to the following criteria:
◎: No peeling of the coating film is observed. ◯: Slight peeling is observed in a part of the coating film on the knife scratches. △: 1 to 20 of 100 peeled squares. In the case of “x”, 21 or more of all 100 goggles have peeled off.

(Note 29) Corrosion resistance: A test plate heat-dried at 95° C. for 20 minutes was used to make a cross-cut scratch with a knife, which was subjected to a salt water spray test for 120 hours in accordance with JIS Z-2371 to prevent rust from the knife scratch. The blister width was evaluated according to the following criteria:
◎ indicates that the maximum width of rust or blisters is less than 2 mm from the cut part (one side),
○ indicates that the maximum width of rust or blisters is 2 mm or more from the cut portion and less than 3 mm (one side),
△ indicates that the maximum width of rust or blisters is 3 mm or more and less than 4 mm (one side) from the cut portion,
× indicates that the maximum width of rust or blisters is 4 mm or more (one side) from the cut portion.

(Note 30) Contamination resistance: Attach the test plate to the installation stand that models the eaves at an angle of 4 degrees from the vertical so that the coating faces the north side, and install Kansai Paint Co., Ltd. in Amagasaki City, Hyogo Prefecture. An exposure test was conducted on the rooftop of the company, and one month after the start of the exposure, the color difference (ΔE) from the initial coated plate was measured according to JIS Z8370 using a multi-source spectrophotometer MSC-5N manufactured by Suga Test Instruments Co., Ltd. It measured using, and evaluated by the following criteria.

◎, △E is less than 1,
○ indicates that ΔE is 1 or more and less than 2,
Δ means that ΔE is 2 or more and less than 5,
× indicates ΔE of 5 or more.

The coating composition of the present invention can provide a coated article excellent in finish, coating hardness, gloss stability of matte coating, chemical resistance and corrosion resistance.

Claims (6)

Hydroxyl group-containing resin (a), barium sulfate (a1) having an average particle diameter of 0.01 to 2.0 μm, talc (a2) having an average particle diameter of 10 μm or more, organic resin particles (a3) and color pigment (a4), and A coating composition containing a polyisocyanate compound (b), comprising:
The hydroxyl group-containing resin (a) is a hydroxyl group-containing acrylic resin,
Based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a), 1 to 130 parts by mass of barium sulfate (a1), 1 to 50 parts by mass of talc (a2), and 0. A coating composition containing 1 to 20 parts by mass, 1 to 100 parts by mass of the color pigment (a4), and 10 to 60 parts by mass of the polyisocyanate compound (b). The coating composition according to claim 1, which contains 0.1 to 10 parts by mass of the silane coupling agent (b1) based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). 0.1 to 10 parts by mass of a stain-proofing agent (b2), which is a condensate of an organosilicate represented by the following formula (1), based on 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a). The coating composition according to claim 1 or 2.
_{^{(R 1) n -Si- (OR}} 2) 4-n ··· Equation (1)
(In formula (1), R ¹ is an alkyl group having 1 to 18 carbon atoms which may be substituted with a mercapto group or a phenyl group, R ² is an alkyl group having 1 to 6 carbon atoms, and n is 0 or 1) The coating composition according to any one of claims 1 to 3, wherein the talc (a2) having an average particle diameter of 10 µm or more has an average particle diameter of 11 to 20 µm. The coating composition according to any one of claims 1 to 4, wherein the organic resin particles (a3) are acrylic resin particles having an average particle diameter of 6 to 22 µm. The object to be coated, the construction machine or the industrial machine having a cured coating film by coating composition according to any one of claims 1-5.