JP2014015533A - Water-base fluorine-containing coating material and article coated with the coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-base fluorine-containing coating material that enables formation of a coating film excellent in surface hardness, solvent resistance, contamination resistance and weather resistance, and an article coated with the coating material.SOLUTION: The water-base fluorine-containing coating material comprises a fluorocarbon resin aqueous dispersion (A), a compound (B) having an epoxy group and a hydrolyzable silyl group, and a water-dispersible polyisocyanate composition (C). The fluorocarbon resin aqueous dispersion (A) is obtained through: a first step of subjecting a monomer mixture (I) to a copolymerization reaction; a second step of adding a monomer mixture (II) to the reactant obtained in the first step to further carry out a copolymerization reaction to obtain a fluorine-containing copolymer (A'); and a third step of neutralizing a carboxyl group possessed by the fluorine-containing copolymer (A') with a basic compound and dispersing the copolymer in an aqueous medium.

Description

  The present invention relates to a water-based fluorine paint capable of forming a paint film having excellent paint film appearance, surface hardness, solvent resistance and stain resistance, and an article coated with the paint.

  A paint using a fluororesin is widely used as a material for forming a protective coating such as an architectural paint or an automobile top coat because it has excellent weather resistance, chemical resistance, and the like. In particular, a two-part curable coating resin composition containing a hydroxyl group-containing fluororesin, a hydroxyl group-reactive curing agent, and an organic solvent has excellent coating film properties (see, for example, Patent Document 1). .)

  However, these organic solvents have a large environmental load, and in recent years, their use has been difficult from the viewpoint of environmental friendliness. For this reason, powder coating resins and aqueous coating resin resins by emulsion polymerization have been developed that have a low environmental impact. However, the resin for powder coatings has a problem that it is not suitable for on-site construction because high temperature baking is required to obtain a coating film. In addition, a method of producing an aqueous fluororesin using an emulsion polymerization method is known, but this emulsion polymerization type aqueous fluororesin is not sufficient in room temperature film-forming property and remains in the coating film after the coating film is prepared. The water resistance is reduced due to the emulsifier, or the traces made by washing the emulsifier with water become pores, and the coating film is eroded from there, and the weather resistance that is an advantage of fluororesin is There were also problems that could not be fully utilized.

  In order to solve the problems of the emulsion polymerization type aqueous resin, a self-dispersion type (dispersion type) aqueous fluororesin that does not use an emulsifier that affects water resistance has been proposed (for example, see Patent Document 2). This self-dispersing aqueous fluororesin is obtained by introducing an acid group such as a carboxyl group into the fluororesin and neutralizing the acid group with a basic compound to impart self-dispersibility in an aqueous medium. . However, although this self-dispersing water-based fluororesin has the advantage of being able to form a film at room temperature and adapting to on-site construction, it has the surface hardness, solvent resistance, and contamination resistance of the resulting coating film. There was a problem of being insufficient.

Japanese Examined Patent Publication No. 6-062910 JP-A-8-337620

  The problem to be solved by the present invention is to provide an aqueous fluorine paint capable of forming a coating film excellent in surface hardness, solvent resistance, stain resistance and weather resistance, and an article coated with the paint.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a basic compound from a fluorine copolymer having a carboxyl group obtained by copolymerizing a monomer mixture having a different composition in two stages. An aqueous fluorine paint containing a fluororesin aqueous dispersion dispersed in an aqueous medium, a compound having an epoxy group and a hydrolyzable silyl group, and a water-dispersible polyisocyanate composition is neutralized with It was found that a coating film excellent in hardness, solvent resistance, stain resistance and weather resistance could be formed, and the present invention was completed.

  That is, the present invention is an aqueous paint containing a fluororesin aqueous dispersion (A), a compound (B) having an epoxy group and a hydrolyzable silyl group, and a water-dispersible polyisocyanate composition (C). Thus, the fluororesin aqueous dispersion (A) is a monomer mixture in which the fluoroolefin compound (a1), the vinyl monomer (a2) having a hydroxyl group, and the vinyl monomer (a3) having a carboxyl group are essential ( Monomer mixture (II) in which the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group are essential to the reaction product obtained in the first step and the first step in which I) is copolymerized. And then further copolymerizing to obtain a fluorine copolymer (A ′), a second step, neutralizing the carboxyl group of the fluorine copolymer (A ′) with a basic compound, Distributed in Through the third step of, an aqueous fluorine coating, characterized in that it is obtained.

  An aqueous fluorine paint comprising a fluororesin aqueous dispersion (A), a compound (B) having an epoxy group and a hydrolyzable silyl group, and a water-dispersible polyisocyanate composition (C), In the first step and the first step, the aqueous resin dispersion (A) is a copolymerization reaction of the monomer mixture (II) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group. A monomer mixture (I) essentially comprising a fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group, and a vinyl monomer (a3) having a carboxyl group was added to the obtained reaction product. Second step of copolymerization to obtain a fluorine copolymer (A ′), neutralizing the carboxyl group of the fluorine copolymer (A ′) with a basic compound and dispersing in an aqueous medium First Through the process, an aqueous fluorine coating, characterized in that it is obtained.

  Furthermore, the present invention relates to an article coated with the water-based fluorine paint.

  The aqueous fluorine paint of the present invention is dispersed in an aqueous medium having a low environmental load, and a coating film can be formed by drying at room temperature. In addition, similar to solvent-based fluorine paints, it has excellent surface hardness, solvent resistance, stain resistance, and weather resistance, so that, for example, it is exposed to direct sunlight and roofs of general buildings that require particularly high weather resistance, and high It is useful as a paint that forms a protective coating on the exterior of factory buildings in complex areas where chemical durability is required.

  The aqueous fluorine paint of the present invention contains an aqueous fluororesin dispersion (A), a compound (B) having an epoxy group and a hydrolyzable silyl group, and a water-dispersible polyisocyanate composition (C).

  First, the fluororesin aqueous dispersion (A) will be described. This fluororesin aqueous dispersion (A) can be obtained by the following two embodiments.

  The first embodiment is a copolymerization reaction of a monomer mixture (I) essentially comprising a fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group and a vinyl monomer (a3) having a carboxyl group. The monomer mixture (II) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group is added to the reaction product obtained in the first step and the first step. Second step of obtaining a fluorine copolymer (A ′) by polymerization reaction, a third step of neutralizing the carboxyl group of the fluorine copolymer (A ′) with a basic compound and dispersing in a water medium This is a method for obtaining a fluororesin aqueous dispersion through the steps.

  In addition, the second aspect is obtained in the first step and the first step in which the monomer mixture (II) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group is copolymerized. A monomer mixture (I) essentially comprising a fluoroolefin compound (a1), a vinyl monomer having a hydroxyl group (a2) and a vinyl monomer having a carboxyl group (a3) was added to the reaction product obtained, Further, the second step of obtaining a fluorine copolymer (A ′) by copolymerization reaction, the carboxyl group of the fluorine copolymer (A ′) is neutralized with a basic compound and dispersed in an aqueous medium. This is a method of obtaining a fluororesin aqueous dispersion through the third step.

  The said fluoro olefin compound (a1) is a compound which has a carbon-carbon unsaturated double bond, and the fluorine atom has couple | bonded with the carbon atom which forms this double bond. Examples of the fluoroolefin compound (a1) include vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, bromotrifluoroethylene, chlorotrifluoroethylene, pentafluoropropylene, hexafluoropropylene, and fluoroalkyltrifluoro. Examples include vinyl ether. Among these, tetrafluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene are preferable because of excellent weather resistance, room temperature film-forming property, and the like. Moreover, these fluoroolefin compounds (a1) can be used alone or in combination of two or more.

  The vinyl monomer (a2) is a compound having a hydroxyl group and a polymerizable carbon-carbon unsaturated double bond. Examples of the vinyl monomer (a2) include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, and 6-hydroxy. Hydroxyalkyl vinyl ether compounds such as hexyl vinyl ether and cyclohexanedimethanol monovinyl ether; Hydroxyallyl ether compounds such as ethylene glycol allyl ether and diethylene glycol allyl ether; Hydroxy such as 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate Examples include alkyl (meth) acrylate compounds. Among these, 2-hydroxyethyl vinyl ether and 4-hydroxybutyl vinyl ether are preferable because of excellent copolymerizability and industrial availability. Moreover, these vinyl monomers (a2) can be used alone or in combination of two or more.

  In the present invention, “(meth) acrylate” refers to one or both of methacrylate and acrylate, and “(meth) acrylic acid” refers to one or both of methacrylic acid and acrylic acid.

  The vinyl monomer (a3) is a compound having a carboxyl group and a polymerizable carbon-carbon unsaturated double bond. Examples of the vinyl monomer (a3) include (meth) acrylic acid, ω-carboxy-polycaprolactone monoacrylate, crotonic acid, 3-butenoic acid, 4-pentenoic acid, 2-hexenoic acid, and 3-hexenoic acid. 5-hexenoic acid, 2-heptenoic acid, 3-heptenoic acid, 6-heptenoic acid, 3-octenoic acid, 7-octenoic acid, 2-nonenoic acid, 3-nonenoic acid, 8-nonenoic acid, 9-decenoic acid Monomers having one carboxyl group such as 10-undecenoic acid, 11-dodecenoic acid, 3-allyloxypropionic acid and allyloxyvaleric acid; single monomers having two carboxyl groups such as itaconic acid, maleic acid and fumaric acid Mer: Monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monoisobutyl fumarate, mono-t-butyl fumarate, monohexyl fumarate , Monooctyl fumarate, mono-2-ethylhexyl fumarate, monomethyl maleate, monoethyl maleate, monobutyl maleate, monoisobutyl maleate, mono-t-butyl maleate, monohexyl maleate, monooctyl maleate, maleic acid Monomers having two carboxyl groups such as mono-2-ethylhexyl, monomethyl itaconate, monoethyl itaconate, monobutyl itaconate, monoisobutyl itaconate, monohexyl itaconate, monooctyl itaconate, mono-2-ethylhexyl itaconate Monoalkyl ester compounds of dicarboxylic acids such as monovinyl adipate, monovinyl succinate, monovinyl maleate, and the like. These vinyl monomers (a3) can be used alone or in combination of two or more.

  Among the above vinyl monomers (a3), when the fluororesin aqueous dispersion (A) is used in the aqueous paint of the present invention in which the compound (B) having an epoxy group and a hydrolyzable silyl group described below is blended. A coating film excellent in surface hardness, solvent resistance and stain resistance is obtained with good reactivity between the carboxyl group of the fluorine copolymer (A ′) and the epoxy group of the compound (B). Therefore, a monomer represented by the following general formula (1) is preferable, and 8-nonenoic acid, 9-decenoic acid, from the viewpoint of excellent polymerizability when the fluorine copolymer (A ′) is synthesized. More preferred are 10-undecenoic acid, 11-dodecenoic acid and the like.

（一般式（１）中、Ｒは、水素原子またはアルキル基を表し、ｎは、６〜９の整数である。）

(In general formula (1), R represents a hydrogen atom or an alkyl group, and n is an integer of 6-9.)

  In addition to the vinyl monomers (a2) and (a3), a vinyl monomer (a4) having no carboxyl group or hydroxyl group may be used as a raw material for the fluorine copolymer (A ′). . Examples of the vinyl monomer (a4) include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, n-pentyl vinyl ether, and n-hexyl. Alkyl vinyl ether compounds such as vinyl ether, n-octyl vinyl ether, 2-ethylhexyl vinyl ether, dodecyl vinyl ether, tridecyl vinyl ether, hexadecyl vinyl ether and octadecyl vinyl ether; cycloalkyl vinyl ether compounds such as cyclohexyl vinyl ether; aralkyl vinyl ether compounds such as benzyl vinyl ether and phenethyl vinyl ether Vinyl ether monomer such as acetic acid Nyl, vinyl propionate, vinyl caproate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate vinyl ester compounds, vinyl pivalate, 2-ethylhexanoic acid Vinyl ester compounds of branched carboxylic acids such as vinyl, vinyl neononanoate and vinyl neodecanoate; vinyl ester compounds of cyclic aliphatic carboxylic acids such as vinyl cyclohexanecarboxylate; vinyl benzoate, vinyl tert-butylbenzoate, etc. Vinyl ester compounds of aromatic carboxylic acids; Olefin compounds such as ethylene and propylene; Halogenated olefin compounds such as vinyl chloride and vinylidene chloride; Allyl ether compounds such as ethyl allyl ether and butyl allyl ether; Allyl acetate and propio Allyl ester compound allyl and the like; methyl (meth) acrylate, butyl (meth) acrylate, etc. (meth) and the like alkyl ester of acrylic acid. When these vinyl monomers (a4) are copolymerized with the vinyl monomers (a2) and (a3) to form the resin composition for water-based paints of the present invention, compatibility with other paint components is achieved. Is preferable because it becomes favorable. Among these vinyl monomers (a4), ethyl vinyl ether and cyclohexyl vinyl ether are preferable because they are easily copolymerized with other monomers and easily available industrially. These vinyl monomers (a4) can be used alone or in combination of two or more.

  Further, as the vinyl monomer (a4), as a monomer having a fluorine atom other than the fluoroolefin compound (a1), 2,2,3,3-tetrafluoropropyl vinyl ether, 2,2,3,3 , 4, 4, 5, 5-octafluoropentyl vinyl ether, perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, perfluoropropyl vinyl ether, perfluorooctyl vinyl ether, perfluorocyclohexyl vinyl ether, and other fluoroalkyl vinyl ether compounds may be used. I do not care.

  In order to produce the fluororesin aqueous dispersion (A), first, the fluorocopolymer (A ′) is produced. Examples of the method for producing the fluorine copolymer (A ′) include the following two methods.

(Manufacturing method 1)
[First step]
The monomer mixture (I) essentially comprising the fluoroolefin compound (a1), the vinyl monomer (a2) having a hydroxyl group, and the vinyl monomer (a3) having a carboxyl group is copolymerized.
[Second step]
To the reaction product obtained in the first step, the monomer mixture (II) having the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group as essential components is added, and further copolymerized.

(Manufacturing method 2)
[First step]
The monomer mixture (II) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group is copolymerized.
[Second step]
In the reaction product obtained in the first step, a monomer mixture in which the fluoroolefin compound (a1), the vinyl monomer (a2) having a hydroxyl group, and the vinyl monomer (a3) having a carboxyl group are essential ( I) is added and the copolymerization is further carried out.

  In addition, in said manufacturing method 1 and manufacturing method 2, even if monomer mixture (I) or monomer mixture (II) used at the 1st process and the 2nd process is charged at once, it is charged in multiple times. It doesn't matter.

  The monomer mixture (I) essentially comprises the fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group, and a vinyl monomer (a3) having a carboxyl group. The monomer (a4) may be contained in the monomer mixture.

  The amount of each monomer used in the monomer mixture (I) is good in weather resistance and chemical resistance, and when used as a resin composition for water-based paints of the present invention, it is compatible with other paint components. Since the solubility becomes good, the total of the vinyl monomers (a2), (a3) and (a4) is 0.6 to 1.5 mol with respect to 1 mol of the fluoroolefin compound (a1). The range is preferable, the range of 0.8 to 1.2 mol is more preferable, and the range of 0.9 to 1.1 mol is more preferable. The molar ratio of the vinyl monomer (a2) in the total of the vinyl monomers (a2), (a3) and (a4) is preferably in the range of 10 to 97 mol%, and 15 to 60 mol%. Is more preferable, and the range of 20 to 50 mol% is more preferable. Furthermore, the molar ratio of the vinyl monomer (a3) in the total of the vinyl monomers (a2), (a3) and (a4) is preferably in the range of 3 to 60 mol%, and 5 to 50 mol%. Is more preferable, and the range of 8 to 40 mol% is more preferable.

  The monomer mixture (II) essentially comprises the fluoroolefin compound (a1) and a vinyl monomer (a2) having a hydroxyl group, but the vinyl monomer (a4) is a simple substance. It may be contained in the monomer mixture.

  The amount of each monomer used in the monomer mixture (II) is excellent in compatibility with other paint components when the resin composition for water-based paints of the present invention is used, and the weather resistance of the coating film. In addition, since the chemical resistance is improved, the total of the vinyl monomers (a2) and (a4) is in the range of 0.6 to 1.5 mol with respect to 1 mol of the fluoroolefin compound (a1). Is preferable, the range of 0.8 to 1.2 mol is more preferable, and the range of 0.9 to 1.1 mol is more preferable. The molar ratio of the vinyl monomer (a2) in the total of the vinyl monomers (a2) and (a4) is preferably in the range of 10 to 100 mol%, more preferably in the range of 15 to 60 mol%. The range of 20 to 50 mol% is more preferable. The monomer mixture (II) may contain a vinyl monomer (a3) having a carboxyl group, but the molar ratio in the monomer mixture (II) is 2 mol. % Or less, more preferably 1.5 mol% or less, still more preferably 1 mol% or less.

  In the monomer mixture (I), the total molar ratio of the vinyl monomers (a2) and (a3) in the total of the vinyl monomers (a2), (a3) and (a4) is 100. In the case of less than mol%, and in the monomer mixture (II), the molar ratio of the vinyl monomer (a2) in the total of the vinyl monomers (a2) and (a4) is less than 100 mol%. In this case, the balance is the vinyl monomer (a4).

  Examples of the polymerization initiator used in the copolymerization reaction performed in the above production methods 1 and 2 include azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile; t-butyl peroxypivalate, t-butyl. Peroxybenzoate, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, lauroyl peroxide, acetyl peroxide, di-t-butyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene Examples thereof include peroxides such as hydroperoxide, methyl ethyl ketone peroxide, and diisopropyl peroxycarbonate. These polymerization initiators can be used alone or in combination of two or more.

  The amount of the polymerization initiator used can be appropriately determined according to the type of polymerization initiator, the polymerization temperature, the molecular weight of the copolymer, etc., but the total amount of monomers to be copolymerized is 100 parts by mass. The range of 0.01 to 10 parts by mass is preferable.

  In the copolymerization reaction performed in the above production methods 1 and 2, as required, lauryl mercaptan, 2-mercaptoethanol, thioglycerol, ethylthioglycolic acid, octylthioglycolic acid, etc. The chain transfer agent may be used.

  Further, the copolymerization reaction is preferably performed in an organic solvent. Various organic solvents can be used as long as they do not inhibit the copolymerization reaction, but in order to obtain the fluororesin aqueous dispersion that is the object of the present invention, an organic solvent miscible with water is mainly used. It is preferable. Examples of the water-miscible organic solvent include alkyl alcohols such as methanol, ethanol, n-propanol, isopropanol, t-butanol, and 3-methoxy-1-butanol; methyl cellosolve, ethyl cellosolve, n-propyl cellosolve, and butyl cellosolve. Glycol ethers such as methyl carbitol, ethyl carbitol, propylene glycol-n-butyl ether, diethylene glycol dimethyl ether and dipropylene glycol dimethyl ether; glycol ether esters such as methyl cellosolve acetate and ethyl cellosolve acetate; dioxane, acetone, methyl ethyl ketone, dimethylformamide, Examples include diacetone alcohol and tetrahydrofuran.

  Among the above organic solvents, when a low boiling point solvent such as acetone, methyl ethyl ketone, or isopropanol, or a solvent that can be azeotroped with water such as butanol or butyl cellosolve is used as a reaction solvent or a dispersion aid, these organic solvents are usually used. It can be easily distilled off under pressure or reduced pressure, and a fluororesin aqueous dispersion with a reduced content of organic solvent can be obtained.

  Moreover, although the reaction temperature in said copolymerization reaction can be performed in the reaction temperature range of normal radical polymerization, the range of 0-150 degreeC is preferable and the range of 40-100 degreeC is more preferable. As reaction time, the range of 1-50 hours is preferable, and the range of 3-30 hours is more preferable.

  The acid value of the fluorocopolymer (A ′) obtained in the second step of the production methods 1 and 2 is in the range of 5 to 35 because water dispersibility is good and high storage stability is obtained. Preferably, the range of 8-33 is more preferable, and the range of 10-32 is more preferable. In addition, the carboxyl group which a fluorine copolymer (A ') has reacts with the epoxy group which the compound (B) which has the said epoxy group and hydrolyzable silyl group reacts, and becomes a crosslinking point.

  When the fluororesin aqueous dispersion (A) is used in the aqueous paint of the present invention containing the water-dispersible polyisocyanate composition (C) described later, a coating film excellent in surface hardness and stain resistance can be obtained. From the above, the hydroxyl value of the fluorine copolymer (A ′) obtained in the second step of the production methods 1 and 2 is preferably in the range of 20 to 200, more preferably in the range of 30 to 150, and 30 to 120. A range is further preferred. In addition, the hydroxyl group which a fluorine copolymer (A ') has reacts with the isocyanate group which the said water dispersible polyisocyanate composition (C) has, and becomes a crosslinking point.

  Further, the weight average molecular weight (Mw) of the fluorocopolymer (A ′) obtained in the second step of the production methods 1 and 2 has good water dispersibility, high storage stability, and water-based paint. Since the surface hardness and stain resistance of the coating film are improved, the range of 5,000 to 100,000 is preferable, the range of 10,000 to 60,000 is more preferable, and 12,000 to 40 is preferable. A range of 1,000 is more preferred. Here, the weight average molecular weight (Mw) is a value converted to polystyrene based on gel permeation chromatography (hereinafter abbreviated as “GPC”) measurement. The measurement conditions for GPC are as follows.

[GPC measurement conditions]
Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series.
"TSKgel G5000" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 “TSKgel G2000” (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 4 mg / mL)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

  Examples of the basic compound used for neutralizing the carboxyl group in the third step of the production methods 1 and 2 include ammonia; alkylamines such as trimethylamine, triethylamine, and butylamine; dimethylaminoethanol, diethanolamine, aminomethylpropanol, and the like. Examples include amino alcohols; polyvalent amines such as ethylenediamine and diethylenetriamine; morpholine. Among these, dimethylaminoethanol is preferable because it is miscible with water and an organic solvent and is volatile and hardly remains in the coating film. These basic compounds can be used alone or in combination of two or more.

  The aqueous medium in which the resin neutralized with the basic compound of the fluorine copolymer (A ′) is dispersed is preferably one containing water as a main component and at least 50% by mass of water. Examples of the water medium that can be used together with water include alkyl alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, and 3-methoxy-1-butanol; methyl cellosolve , Ethyl cellosolve, n-propyl cellosolve, butyl cellosolve, hexyl cellosolve, glycol ethers such as methylcarbyl, ethyl carbitol, propylene glycol-n-butyl ether; glycol ether esters such as methyl cellosolve acetate, ethyl cellosolve acetate; or dioxane, dimethyl Examples include formamide, diacetone alcohol, and tetrahydrofuran. Moreover, these aqueous media can be used alone or in combination of two or more.

  Next, the compound (B) having the epoxy group and hydrolyzable silyl group will be described. In this compound (B), the epoxy group reacts with the carboxyl group of the aqueous fluororesin dispersion (A), and the hydrolyzable silyl groups hydrolyze and condense, whereby the curing agent for the aqueous fluorine paint of the present invention. Function as.

  Examples of the compound (B) having an epoxy group and a hydrolyzable silyl group include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 3- Compounds having an epoxy group and an alkoxysilyl group, such as glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane Among them, 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane are preferable because a coating film having excellent surface hardness, solvent resistance, and stain resistance can be obtained. . These compounds may be used alone or in combination of two or more.

  The amount of the compound (B) having the epoxy group and hydrolyzable silyl group is such that a coating film excellent in surface hardness, solvent resistance and stain resistance can be obtained. Equivalent ratio (EP / COOH) of the epoxy group (EP) of the compound (B) having a group and the carboxyl group (COOH) of the fluorine copolymer (A ′) in the fluororesin aqueous dispersion (A) Is preferably in the range of 0.5 to 2.0, more preferably in the range of 0.7 to 1.5, and more preferably in the range of 1.0 to 1.3.

  The water dispersible polyisocyanate composition (C) will be described. This water-dispersible polyisocyanate composition (C) functions as a curing agent for the aqueous fluorine paint of the present invention by reacting with the hydroxyl group of the aqueous fluororesin dispersion (A).

  The water-dispersible polyisocyanate composition (C) only needs to have water-dispersibility. For example, (1) a mixture of a hydrophobic polyisocyanate (c1) and a water-dispersible polyisocyanate (c2), (2) A mixture of a hydrophobic polyisocyanate (c1) and a dispersant (c3) having no isocyanate group and having a hydrophilic group, (3) polyisocyanate (c2) having water dispersibility, and the like.

  Examples of the hydrophobic polyisocyanate (c1) include those having no hydrophilic group such as an anionic group, a cationic group, and a nonionic group in the molecule. For example, 1,4-tetramethylene diisocyanate, ethyl (2,6-diisocyanate) hexanoate, 1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc. Aliphatic diisocyanates; aliphatic triisocyanates such as 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanate-4-isocyanate methyloctane, 2-isocyanatoethyl (2,6-diisocyanate) hexanoate Isocyanate; 1,3-bis (iso Anatomethylcyclohexane), 1,4-bis (isocyanatomethylcyclohexane), 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, 3,5,5-trimethyl (3-isocyanatomethyl) Cycloaliphatic diisocyanates such as cyclohexyl isocyanate, dicyclohexylmethane-4,4′-diisocyanate, 2,5-diisocyanatomethylnorbornane, 2,6-diisocyanatomethylnorbornane; 2,5-diisocyanatomethyl-2 -Alicyclic triisocyanates such as isocyanatopropyl norbornane and 2,6-diisocyanatomethyl-2-isocyanate propyl norbornane; m-xylylene diisocyanate, α, α, α ', α'-tetramethyl- m-xylylene diisocyanate Aralkylene diisocyanates such as anate; m-phenylene diisocyanate, p-phenylene diisocyanate, tolylene-2,4-diisocyanate, 2,6-diisocyanate, diphenylmethane-4,4′-diisocyanate, naphthalene-1,5-diisocyanate, diphenyl- Aromatic diisocyanates such as 4,4'-diisocyanate, 4,4'-diisocyanate-3,3'-dimethyldiphenyl, 3-methyl-diphenylmethane-4,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate Aromatic triisocyanates such as triphenylmethane triisocyanate and tris (isocyanatophenyl) thiophosphate; various diisocyanates as described above or isocyanates of triisocyanates A polyisocyanate having a uretdione structure obtained by cyclizing and dimerizing groups; a polyisocyanate having an isocyanurate structure obtained by cyclizing and trimerizing the isocyanate groups of the various diisocyanates or triisocyanates described above; Polyisocyanate having a burette structure obtained by reacting diisocyanate or triisocyanate with water with water; polyisocyanate having an oxadiazine trione structure obtained by reacting various diisocyanates or triisocyanates with carbon dioxide; allophanate structure The polyisocyanate etc. which have are mentioned.

  Examples of the water-dispersible polyisocyanate (c2) include polyisocyanates having hydrophilic groups such as anionic groups, cationic groups, and nonionic groups.

  Examples of the water-dispersible polyisocyanate (c2) include polyethers, polyesters, polyurethanes, vinyl polymers, alkyd resins, fluororesins, and silicone resins having an isocyanate group and a hydrophilic group. Can be used alone or in combination of two or more.

  Examples of the dispersant (c3) having no isocyanate group but having a hydrophilic group include, for example, an acrylic polymer, a fluoroolefin polymer, a vinyl ester polymer having no isocyanate group but having a hydrophilic group, An aromatic vinyl polymer, a polyolefin polymer, etc. are mentioned.

  The water-dispersible polyisocyanate composition (C) can be used alone or in combination of two or more.

  The water-dispersible polyisocyanate composition (C) is used in an amount of an isocyanate group (NCO) contained in the polyisocyanate composition and a fluororesin aqueous solution because a coating film having excellent surface hardness and stain resistance can be obtained. The range in which the equivalent ratio (NCO / OH) to the hydroxyl group (OH) of the fluorocopolymer (A ′) in the dispersion is 0.5 to 2.0 is preferable, and 0.7 to 1.5. A range is more preferable, and a range of 1.0 to 1.3 is more preferable.

  The aqueous fluorine paint of the present invention includes inorganic pigments, organic pigments, extender pigments, dyes, waxes, surfactants, stabilizers, flow regulators, antifoaming agents, leveling agents, rheology control agents, ultraviolet rays as necessary. Various additives such as an absorbent, a light stabilizer, an antioxidant, and a plasticizer can be blended.

  In addition, the water-based fluorine paint of the present invention includes, for example, metals such as iron, nickel, aluminum, copper, and lead; alloys containing these metals; Various surface-treated metals that have been plated or chemically treated; thermoplastic resins such as polystyrene, polymethyl methacrylate, ABS resin, polyphenylene oxide, polyurethane, polyethylene, polyvinyl chloride, polypropylene, polybutylene terephthalate, and polyethylene terephthalate; unsaturated Examples thereof include thermosetting resins such as polyester resins, phenol resins, and crosslinked polyurethanes; molded articles such as the above metals and resins; and construction members such as concrete, slate, tile, tile, glass, and wooden building materials.

  Furthermore, the coating film of the aqueous fluorine paint of the present invention is particularly excellent in chemical stability and has a long coating film life, so that it can be used in harsh environments such as roof substrates and chemical factory buildings, It can be suitably used as a material for protecting building articles such as high-rise building outer walls and large bridges that are difficult to repaint.

  In addition, the water-based fluorine paint of the present invention can be coated with a thick film in applications requiring a long-term protection function such as heavy anticorrosion coating, and a coating film thickness of 40 μm or more after drying is formed. You can also

  Next, the present invention will be specifically described with reference to examples and comparative examples. In addition, the acid value of a polymer is measured based on JIS test method K0070-1992. The number average molecular weight (Mn) and the weight average molecular weight (Mw) are measured under the following GPC measurement conditions.

[GPC measurement conditions]
Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series.
"TSKgel G5000" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 “TSKgel G2000” (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 4 mg / mL)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

(Synthesis Example 1: Production of aqueous fluororesin dispersion (A-1))
[First step]
91.9 parts by mass of diethylene glycol dimethyl ether (hereinafter abbreviated as “MDM”), 127.1 parts by mass of methanol, and ethyl vinyl ether (hereinafter abbreviated as “EVE”) in a stainless steel autoclave substituted with nitrogen inside. ) 28.9 parts by mass, 4-hydroxybutyl vinyl ether (hereinafter abbreviated as “HBVE”) 20.6 parts by mass, cyclohexyl vinyl ether (hereinafter abbreviated as “CHVE”) 2.1 parts by mass, 10 − 26.8 parts by mass of undecenoic acid (hereinafter abbreviated as “UDA”), light stabilizer (“Tinuvin 292” manufactured by BASF Japan Ltd., bis (1,2,2,6,6-pentamethyl-4-piperidinyl) ) A mixture of sebacate and methyl (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; Below. Abbreviated as "HALS") 16.5 parts by mass, and was charged with t- butyl peroxypivalate 4.0 part by weight as a polymerization initiator. Next, 86.6 parts by mass of liquefied chlorotrifluoroethylene (hereinafter abbreviated as “CTFE”) was injected into the autoclave, and then the autoclave was heated to 63 ° C. Subsequently, while maintaining the temperature at 63 ° C., 144.4 parts by mass of liquefied CTFE was injected over 1.5 hours. Simultaneously with the start of the injection of CTFE, EVE 48.1 parts by mass, HBVE 34.4 parts by mass, CHVE 3.4 parts by mass, UDA 44.7 parts by mass, MDM 33 parts by mass, methanol 33 parts by mass, and t-butyl peroxypivalate. A mixture of 6 parts by mass was injected over 1.5 hours.

[Second step]
After the completion of the monomer injection in the first step, 379.5 parts by mass of liquefied CTFE was continuously injected into the autoclave over 2.5 hours. Also, a mixture comprising 160.6 parts by mass of EVE, 108.9 parts by mass of HBVE, 11 parts by mass of CHVE, 79.2 parts by mass of MDM, 79.2 parts by mass of methanol, and 15.8 parts by mass of t-butyl peroxypivalate as a polymerization initiator. Was pressed in over 3.5 hours. After the press-fitting, 35.2 parts by mass of MDM was press-fitted for washing the press-fitting line. The autoclave was kept at 63 ° C. and reacted for 12 hours from the start of CTFE injection in the first step. Then, the internal pressure of the autoclave was returned to normal pressure, and 1418 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 72 parts by mass of an inorganic synthetic adsorbent (“Kyoward 500 (G7)” manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred at 60 ° C. for 4 hours. Subsequently, filtration was performed, and the filtrate was distilled off under reduced pressure to obtain an 81.5 mass% solution of the fluorine copolymer (A′-1). The acid value of this fluorocopolymer (A′-1) was 17.5 mgKOH / g, the number average molecular weight (Mn) was 7,200, and the weight average molecular weight (Mw) was 21,100.

[Third step]
500 parts by mass of the fluorocopolymer solution obtained in the second step and 43.3 parts by mass of 3-methoxybutanol were put into a 2 liter four-necked flask, heated to 40 ° C., and then dimethylethanolamine 11.1. After adding 1 part by mass, stirring for 1 hour to make uniform, the temperature was raised to 60 ° C. and 464.3 parts by mass of ion-exchanged water was gradually added while stirring to obtain a fluororesin having a nonvolatile content of 39.3% by mass. An aqueous dispersion (A-1) was obtained.

(Synthesis Example 2: Production of fluororesin aqueous dispersion (A-2))
[First step]
In an autoclave made of stainless steel whose inside is replaced with nitrogen, 91.9 parts by mass of MDM, 127.1 parts by mass of methanol, 37.1 parts by mass of EVE, 20.6 parts by mass of HBVE, 2.1 parts by mass of CHVE, 13.6 parts by mass of UDA, HALS16 .5 parts by mass, and 4.0 parts by mass of t-butyl peroxypivalate as a polymerization initiator were charged. Next, 91.6 parts by mass of liquefied CTFE was pressed into the autoclave, and then the autoclave was heated to 63 ° C. Subsequently, while maintaining the temperature at 63 ° C., 152.6 parts by mass of liquefied CTFE was injected over 1.5 hours. Simultaneously with the start of CTFE injection, it consists of 61.9 parts by weight of EVE, 34.4 parts by weight of HBVE, 3.4 parts by weight of CHVE, 22.7 parts by weight of UDA, 33 parts by weight of MDM, and 6.6 parts by weight of t-butyl peroxypivalate. The mixture was pressed in over 1.5 hours.

[Second step]
After completion of the injection of the monomer in the first step, 380.6 parts by mass of liquefied CTFE was continuously injected into the autoclave over 2.5 hours. In addition, a mixture of 159.5 parts by mass of EVE, 108.9 parts by mass of HBVE, 11 parts by mass of CHVE, 79.2 parts by mass of MDM, 79.2 parts by mass of methanol, and 15.8 parts by mass of t-butyl peroxypivalate was added to 3.5 parts. Press fit over time. After the press-fitting, 35.2 parts by mass of MDM was press-fitted for washing the press-fitting line. The autoclave was kept at 63 ° C. and reacted for 12 hours after the start of CTFE injection in the first step. Then, the internal pressure of the autoclave was returned to normal pressure, and 1470.5 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 72 parts by mass of an inorganic synthetic adsorbent (“Kyoward 500 (G7)” manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred at 60 ° C. for 4 hours. Subsequently, filtration was performed, and the filtrate was distilled off under reduced pressure to obtain an 83.5 mass% solution of the fluorine copolymer (A′-2). The acid value of this fluorocopolymer (A′-2) was 8.5 mgKOH / g, the number average molecular weight (Mn) was 8,500, and the weight average molecular weight (Mw) was 27,400.

[Third step]
500 parts by mass of the fluorocopolymer solution obtained in the second step and 56.7 parts by mass of 3-methoxybutanol are put into a 2 liter four-necked flask, heated to 40 ° C., and then dimethylethanolamine 5.4. After adding part by mass and stirring for 1 hour to make uniform, the temperature was raised to 60 ° C., and 481.6 parts by mass of ion-exchanged water was gradually added while stirring to obtain a fluororesin having a nonvolatile content of 39.1% by mass. An aqueous dispersion (A-2) was obtained.

(Synthesis example 3: Production of fluororesin aqueous dispersion (A-3))
[First step]
In an autoclave made of stainless steel whose inside is replaced with nitrogen, 91.9 parts by mass of MDM, 127.1 parts by mass of methanol, 20.2 parts by mass of EVE, 20.6 parts by mass of HBVE, 2.1 parts by mass of CHVE, 41.3 parts by mass of UDA, HALS16 .5 parts by mass, and 4.0 parts by mass of t-butyl peroxypivalate as a polymerization initiator were charged. Next, 80.9 parts by mass of liquefied CTFE was injected into the autoclave, and then the autoclave was heated to 63 ° C. Subsequently, 134.7 parts by mass of liquefied CTFE was injected over 1.5 hours while maintaining the temperature at 63 ° C. Simultaneously with the start of CTFE injection, 33.7 parts by mass of EVE, 34.4 parts by mass of HBVE, 3.4 parts by mass of CHVE, 68.7 parts by mass of MDA, 33.0 parts by mass of MDM, 33.0 parts by mass of methanol, and t-butylperoxypi A mixture consisting of 6.6 parts by mass of barate was injected over 1.5 hours.
[Second step]
After completion of the injection of the monomer in the first step, 380.6 parts by mass of liquefied CTFE was continuously injected into the autoclave over 2.5 hours. Further, a mixture of 159.5 parts by mass of EVE, 108.9 parts by mass of HBVE, 11.0 parts by mass of CHVE, 79.2 parts by mass of MDM, 79.2 parts by mass of methanol, and 15.8 parts by mass of t-butyl peroxypivalate was obtained. Press-fit over 5 hours. After the press-fitting, 35.2 parts by mass of MDM was press-fitted for washing the press-fitting line. The autoclave was kept at 63 ° C. and reacted for 12 hours after the start of CTFE injection in the first step. Then, the internal pressure of the autoclave was returned to normal pressure, and 1402 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 72.0 parts by mass of an inorganic synthetic adsorbent (“Kyoward 500 (G7)” manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred at 60 ° C. for 4 hours. did. Subsequently, filtration was performed, and the filtrate was distilled off under reduced pressure to obtain an 81.9% by mass solution of a fluorine copolymer (A′-3). The acid value of this fluorocopolymer (A′-3) was 25.1 mgKOH / g, the number average molecular weight (Mn) was 6,200, and the weight average molecular weight (Mw) was 22,200.
[Third step]
500 parts by mass of the fluorocopolymer solution obtained in the second step and 46.0 parts by mass of 3-methoxybutanol are placed in a 2 liter four-necked flask and heated to 40 ° C., and then 15.9 dimethylethanolamine. After adding 1 part by mass, stirring for 1 hour to make uniform, the temperature was raised to 60 ° C., and 461.8 parts by mass of ion-exchanged water was gradually added while stirring to obtain a fluororesin having a nonvolatile content of 39.6% by mass. An aqueous dispersion (A-3) was obtained.

(Synthesis Example 4: Production of fluororesin aqueous dispersion (A-4))
[First step]
In an autoclave made of stainless steel, the inside of which was replaced with nitrogen, 91.9 parts by mass of MDM, 127.1 parts by mass of methanol, 28.9 parts by mass of EVE, 20.6 parts by mass of HBVE, 2.1 parts by mass of CHVE, 16.5 parts by mass of HALS, and As a polymerization initiator, 4.0 parts by mass of t-butyl peroxypivalate was charged. Next, 86.6 parts by mass of liquefied CTFE was injected into the autoclave, and then the autoclave was heated to 63 ° C. Subsequently, while maintaining the temperature at 63 ° C., 294.0 parts by mass of liquefied CTFE was injected over the course of 2.5 hours. Simultaneously with the start of CTFE injection, EVE 130.6 parts by mass, HBVE 88.3 parts by mass, CHVE 8.9 parts by mass, MDM 59.4 parts by mass, methanol 59.4 parts by mass, and t-butyl peroxypivalate 11.8 parts by mass The mixture consisting of was pressed over 2.5 hours.
[Second step]
After the completion of the monomer injection in the first step, 215.6 parts by mass of liquefied CTFE was continuously injected into the autoclave over 1.5 hours. Also, EVE 53.9 parts by mass, HBVE 55.0 parts by mass, CHVE 5.5 parts by mass, UDA 110.0 parts by mass, MDM 52.8 parts by mass, methanol 52.8 parts by mass, and t-butyl peroxypivalate 10.6 parts by mass. The mixture consisting of parts was pressed over 2.5 hours. After the press-fitting, 35.2 parts by mass of MDM was press-fitted for washing the press-fitting line. The autoclave was kept at 63 ° C. and reacted for 12 hours from the start of CTFE injection in the first step. Then, the internal pressure of the autoclave was returned to normal pressure, and 1431 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 72.0 parts by mass of an inorganic synthetic adsorbent (“Kyoward 500 (G7)” manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred at 60 ° C. for 4 hours. did. Subsequently, filtration was performed, and the filtrate was distilled off under reduced pressure to obtain an 82.4% by mass solution of a fluorine copolymer (A′-4). The acid value of this fluorocopolymer (A′-4) was 25.0 mgKOH / g, the number average molecular weight (Mn) was 4,700, and the weight average molecular weight (Mw) was 18,100.
[Third step]
500 parts by mass of the fluorocopolymer solution obtained in the second step and 49.3 parts by mass of 3-methoxybutanol were put into a 2 liter four-necked flask, heated to 40 ° C., and then dimethylethanolamine 15.9. After adding 1 part by mass and stirring for 1 hour to make uniform, the temperature was raised to 60 ° C. and 464.8 parts by mass of ion-exchanged water was gradually added while stirring to obtain a fluororesin having a nonvolatile content of 39.5% by mass. An aqueous dispersion (A-4) was obtained.

  Table 1 shows the compositions and properties of the fluororesin aqueous dispersions (A-1) to (A-4) obtained above.

(Formulation Example 1: Preparation of water-based fluorine paint main agent (T-1))
Aqueous fluororesin dispersion (A-1) 152.7 parts by mass (60 parts by mass as fluororesin), 140 parts by mass of titanium oxide (“Typure R-706” manufactured by DuPont), and 40.6 parts by mass of ion-exchanged water Parts were mixed to obtain a pigment mixture. The pigment mixture had a PWC (percentage of the pigment mass with respect to the solid mass) of 70% by mass and a non-volatile content of 60% by mass. This pigment mixture was dispersed using a batch mill to obtain a pigment dispersion. 343.5 parts by mass of the fluororesin aqueous dispersion (A-1), 2 parts by mass of a surfactant (“BYK-348” manufactured by Big Chemie Japan Co., Ltd.), an antifoaming agent, with respect to 300 parts by mass of the pigment dispersion (San Nopco "SN deformer 777") 0.7 parts by weight and 11 parts by weight of ion-exchanged water were added and then mixed uniformly to form a water-based fluorine paint main component having a PWC of 40% by weight and a nonvolatile content of 48% by weight. (T-1) was prepared.

(Formulation Examples 2 to 5: Preparation of water-based fluorine paint main ingredients (T-2) to (T-4))
By operating in the same manner as in Formulation Example 1 except that the fluororesin aqueous dispersion (A-1) is changed to (A-2) to (A-4), water-based fluorocoating paints (T-2) to (T -4) was prepared.

(Example 1: Preparation and evaluation of water-based fluorine paint (1))
With respect to 50 parts by mass of the water-based fluorine paint main component (T-1), as a curing agent, a water-dispersible polyisocyanate (“Bernock DNW-5500” manufactured by DIC Corporation, non-volatile content: 80% by mass; hereinafter, “DNW-5500 ) 6.2 parts by mass and 3-glycidoxypropyltrimethoxysilane (hereinafter abbreviated as “GPTMS”) 1.3 parts by mass, and then mixed uniformly to obtain aqueous fluorine. A paint (1) was prepared. In addition, the equivalent ratio [(NCO) / (OH)] of the isocyanate group (NCO) and the hydroxyl group (OH) in the fluororesin aqueous dispersion (A-1) is 1.2, and the epoxy group (EP) The equivalent ratio [(EP) / (COOH)] to the carboxyl group (COOH) in the fluororesin aqueous dispersion (A-1) was 1.2. DNW-5500 and GPTMS were mixed immediately before coating.

<Creation of coating film for evaluation>
The aqueous fluorine paint (1) obtained above was applied to a zinc phosphate-treated steel sheet (JIS G3141 (SPCC-SD) PB-44 manufactured by Nippon Test Panel Co., Ltd.) using a spray gun, and then 23 ° C. The film was dried in a constant temperature room for 7 days to produce a coating film having a thickness of 40 μm.

<Appearance evaluation>
About the coating film obtained above, using a gloss meter (“Gloss meter GM-26D” manufactured by Murakami Color Research Laboratory), 60 ° glossiness and 20 ° glossiness were each measured at 5 points. The average value was taken as the measured value.

<Evaluation of surface hardness>
About the coating film obtained above, based on JIS test method K5600-5-4: 1999, pencil hardness was measured using "Uni" by Mitsubishi Pencil Co., Ltd. for the pencil.

<Evaluation of solvent resistance>
The coating film obtained above was set in “RUBBING TESTER” manufactured by Ohira Rikagaku Kogyo, and the number of reciprocations until the substrate was seen with a load of 1 kg was measured using a felt in which xylene was sufficiently immersed.

<Evaluation of weather resistance>
The coating film obtained above was subjected to an accelerated weather resistance test using a sunshine weatherometer (manufactured by Suga Test Instruments Co., Ltd.) (hereinafter abbreviated as “SWOM”).
Glass filter type: A
Irradiance: 255 ± 10 W / m ² (wavelength range 300 to 700 nm)
Black panel temperature: 63 ± 3 ℃
Irradiation and spraying method: 120 minute cycle (102 minutes of irradiation followed by 18 minutes of irradiation and spraying)
A value obtained by dividing the 60-degree specular reflectance (%) of the cured coating film after 3,000 hours test using SWOM by 100 times by dividing by the 60-degree specular reflectance (%) of the untested cured coating film. Displayed as gloss retention (%).

<Evaluation of contamination resistance>
On the coating film obtained above, a black, blue and red magic ink large size (product of Teranishi Chemical Industry Co., Ltd.) was used to draw a straight line having a length of 4 to 5 cm and stored in a thermostatic chamber at 23 ° C. for 24 hours. Next, a solvent in which equal parts by mass of petroleum benzine and ethanol were mixed was sufficiently soaked in absorbent cotton, and the drawn straight line was wiped once while pressing. At this time, the state of the ink remaining on the coating film was evaluated as contamination.
A: No trace O: There is a trace, but the shape of the original line cannot be determined.
Δ: There is a thin trace, and the shape of the original line can be identified.
X: A trace remains clearly.

(Examples 2 to 6: Preparation and evaluation of water-based fluorine paints (2) to (6))
Aqueous fluorine paints (2) to (6) were prepared by operating in the same manner as in Example 1 except that the composition was changed to the composition shown in Table 2 below. Subsequently, the coating film evaluation was performed in the same manner as in Example 1.

  Table 2 shows the composition of the aqueous fluorine paints (1) to (6) prepared in Examples 1 to 6 and the evaluation results of the coating films.

(Comparative Examples 1 and 2: Preparation and evaluation of comparative water-based fluorine paints (R-1) and (R-2))
Aqueous fluorine paints (R-1) and (R-2) were prepared in the same manner as in Example 1 except that the composition was changed to the composition shown in Table 3 below. Subsequently, the coating film evaluation was performed in the same manner as in Example 1.

  Table 3 shows the composition of the comparative aqueous fluorine paints (R-1) and (R-2) prepared in Comparative Examples 1 and 2 and the evaluation results of the coating film.

  From the evaluation results of Examples 1 to 6 shown in Table 2, it was found that the aqueous fluorine paint of the present invention can form a coating film excellent in surface hardness, solvent resistance, stain resistance and weather resistance. .

  From the evaluation results of Comparative Examples 1 and 2 shown in Table 3, the following was found.

  Comparative Example 1 is an example in which the water-based fluorine paint does not contain a compound having an epoxy group and a hydrolyzable silyl group, but it is found that the obtained coating film is inferior in surface hardness, solvent resistance, and stain resistance. It was.

  Although the comparative example 2 is an example which does not contain a water-dispersible polyisocyanate composition in a water-based fluorine paint, it turned out that it is inferior to the solvent resistance of a coating film obtained, and stain resistance.

Claims (6)

  An aqueous fluorocoating composition comprising an aqueous fluororesin dispersion (A), a compound (B) having an epoxy group and a hydrolyzable silyl group, and a water-dispersible polyisocyanate composition (C), the fluororesin aqueous Dispersion (A) is a copolymer of monomer mixture (I) essentially comprising a fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group and a vinyl monomer (a3) having a carboxyl group. In the first step to be reacted, a monomer mixture (II) essentially comprising a fluoroolefin compound (a1) and a vinyl monomer having a hydroxyl group (a2) is added to the reaction product obtained in the first step, and Second step of obtaining a fluorine copolymer (A ′) by copolymerization reaction, a step of neutralizing the carboxyl group of the fluorine copolymer (A ′) with a basic compound and dispersing it in an aqueous medium. 3 steps The aqueous fluorine coating, characterized in that is obtained through.   An aqueous fluorocoating composition comprising an aqueous fluororesin dispersion (A), a compound (B) having an epoxy group and a hydrolyzable silyl group, and a water-dispersible polyisocyanate composition (C), the fluororesin aqueous The dispersion (A) is obtained in the first step and the first step in which a monomer mixture (II) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group is copolymerized. The monomer mixture (I) essentially comprising the fluoroolefin compound (a1), the vinyl monomer (a2) having a hydroxyl group, and the vinyl monomer (a3) having a carboxyl group was added to the reaction product, Second step of obtaining a fluorine copolymer (A ′) by copolymerization reaction, a step of neutralizing the carboxyl group of the fluorine copolymer (A ′) with a basic compound and dispersing it in an aqueous medium. 3 steps After, the aqueous and characterized in that the resulting fluorine coating.   The monomer mixture (I) or (II) includes the vinyl monomer (a4) other than the fluoroolefin compound (a1), the vinyl monomer (a2), and the vinyl monomer (a3). The water-based fluorine paint according to claim 1 or 2.   The amount of each monomer used in the monomer mixture (I) is the sum of the vinyl monomers (a2), (a3) and (a4) with respect to 1 mol of the fluoroolefin compound (a1). The molar ratio of the vinyl monomer (a2) in the total of the vinyl monomers (a2), (a3) and (a4) is 10 to 1.5 mol. The molar ratio of the vinyl monomer (a3) in the total of the vinyl monomers (a2), (a3) and (a4) is in the range of 3 to 60 mol%. The amount of each monomer used in the monomer mixture (II) is 0 in total of the vinyl monomers (a2) and (a4) with respect to 1 mol of the fluoroolefin compound (a1). The vinyl in the total of the vinyl monomers (a2) and (a4) Mer (a2) according to claim 3, wherein the aqueous fluorine paint molar ratio is in the range of 10 to 100 mole percent. The water-based fluorine paint according to claim 1, wherein the vinyl monomer (a3) is represented by the following general formula (1).

(In general formula (1), R represents a hydrogen atom or an alkyl group, and n is an integer of 6-9.)   An article coated with the water-based fluorine paint according to any one of claims 1 to 5.