JP2013170220A - Fluororesin aqueous dispersion, aqueous fluorine coating material and article coated with the coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluororesin aqueous dispersion, which can be produced in an easy process, and with which a coating film with high weather resistance can be formed, and which shows excellent long-term storage stability.SOLUTION: A fluororesin aqueous dispersion is obtained, for example, through the following steps: a first step of copolymerizing a monomer mixture (I) essentially comprising a fluoroolefin compound (a1) and a vinyl monomer (a2) having a hydroxyl group; a second step of adding a monomer mixture (II) essentially comprising a fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group and a vinyl monomer (a3) having a carboxyl group to the reaction product obtained in the first step to further copolymerize it to obtain a fluororesin (A); and a third step of neutralizing the carboxyl group possessed by the fluororesin (A) with a basic compound, and dispersing it in an aqueous medium.

Description

  The present invention relates to an aqueous fluororesin dispersion in which a fluorocopolymer is dispersed in an aqueous medium, an aqueous fluorine paint using this dispersion, 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, the two-component curable coating resin composition described in Patent Document 1 includes aromatic solvents such as toluene and xylene, ester solvents such as ethyl acetate and butyl acetate, and ketones such as methyl ethyl ketone and methyl isobutyl ketone. Since it contains an organic solvent (strong solvent) with relatively high solubility, such as a solvent, it erodes the painted surface and is difficult to use for repairing the coating. In addition, 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 low erosion on the painted surface and 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. . This self-dispersing water-based fluororesin can be applied on-site, has excellent film-forming properties at room temperature, and has excellent mechanical stability. Therefore, there has been a problem that the weather resistance decreases as the water resistance of the coating film decreases.

  Proposal to improve the dispersibility of fluororesin aqueous dispersion by mixing and dispersing components with many acid groups and components with few acid groups as a method to improve water dispersion stability of fluororesins with few acid groups (For example, refer to Patent Document 3). However, in this method, a compound having an acid group such as methacrylic acid and an unsaturated group is esterified with the hydroxyl group of the fluororesin to introduce an unsaturated group into the resin, and acrylic acid is further added to the unsaturated group. It is necessary to introduce a graft chain by copolymerizing a monomer having an acid group such as acid or methacrylic acid with a (meth) acrylic acid ester, and there is a problem that the operation for producing the fluororesin becomes complicated. There is also a problem that the storage stability of the fluororesin aqueous dispersion is low.

Japanese Examined Patent Publication No. 6-062910 JP-A-8-337620 Japanese Patent Laid-Open No. 2-233749

  The problem to be solved by the present invention is to provide a fluororesin aqueous dispersion that can be produced by a simple method, can form a highly weather-resistant coating film, and has excellent long-term storage stability. It is to be. Another object of the present invention is to provide an aqueous fluorine paint containing the dispersion 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. It was found that the aqueous dispersion of fluororesin dispersed in an aqueous medium after neutralizing with the above can form a highly weather-resistant coating film and has excellent long-term storage stability. Completed.

That is, the present invention comprises a first step of copolymerizing a monomer mixture (I) essentially comprising a fluoroolefin compound (a1) and a vinyl monomer (a2) having a hydroxyl group,
Monomer mixture (II) in which the reaction product obtained in the first step essentially comprises a fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group and a vinyl monomer (a3) having a carboxyl group. ) And further copolymerization reaction to obtain a fluorine copolymer (A),
The present invention relates to an aqueous fluorocopolymer dispersion, which is obtained through a third step of neutralizing a carboxyl group of the fluorocopolymer (A) with a basic compound and dispersing it in an aqueous medium.

Also, a first step of copolymerizing a monomer mixture (II) essentially comprising a fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group and a vinyl monomer (a3) having a carboxyl group ,
To the reactant obtained in the first step, the monomer mixture (I) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group is added, and further copolymerized, A second step of obtaining a fluorine copolymer (A),
The present invention relates to a fluororesin aqueous dispersion, which is obtained through a third step of neutralizing a carboxyl group of the fluorocopolymer (A) with a basic compound and dispersing it in an aqueous medium.

  Furthermore, the present invention relates to an aqueous fluorine paint using the aqueous fluororesin dispersion and an article coated with the paint.

  The aqueous fluororesin dispersion of the present invention does not use an emulsifier, is dispersed in an aqueous medium with a low environmental load, can form a highly weather-resistant coating film by drying at room temperature, and has excellent mechanical stability. In addition, it has excellent long-term storage stability. Therefore, it can be used for an aqueous fluorine paint. In addition, the water-based fluorine paint using the aqueous fluororesin dispersion of the present invention has high weather resistance, light resistance, and chemical resistance like the solvent-based fluorine paint, so that it is exposed to direct sunlight, for example, and has particularly high weather resistance. It is useful as a paint to form a protective coating on the roof of general buildings that require high properties and the exterior of factory buildings in complex areas where high chemical durability is required.

  The aqueous fluororesin dispersion of the present invention can be obtained by the following two aspects.

The first aspect is a first step of copolymerizing the monomer mixture (I) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group,
Monomer mixture (II) in which the reaction product obtained in the first step essentially comprises a fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group and a vinyl monomer (a3) having a carboxyl group. ) And further copolymerization reaction to obtain a fluorine copolymer (A),
This is a method of obtaining a fluororesin aqueous dispersion through a third step in which the carboxyl group of the fluorocopolymer (A) is neutralized with a basic compound and dispersed in an aqueous medium.

In the second embodiment, the monomer mixture (II) comprising the fluoroolefin compound (a1), the vinyl monomer (a2) having a hydroxyl group, and the vinyl monomer (a3) having a carboxyl group as essential components is used. A first step of polymerization reaction;
To the reactant obtained in the first step, the monomer mixture (I) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group is added, and further copolymerized, A second step of obtaining a fluorine copolymer (A),
This is a method of obtaining a fluororesin aqueous dispersion through a third step in which the carboxyl group of the fluorocopolymer (A) is neutralized with a basic compound and dispersed in an aqueous medium.

  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, 3-allyloxypropionic acid and allyloxyvaleric acid; monomers having two carboxyl groups such as itaconic acid, maleic acid and fumaric acid; fumaric acid Monomethyl, monoethyl fumarate, monobutyl fumarate, monoisobutyl fumarate, mono-t-butyl fumarate, monohexyl fumarate, monoo fumarate Chill, mono-2-ethylhexyl fumarate, monomethyl maleate, monoethyl maleate, monobutyl maleate, monoisobutyl maleate, mono-t-butyl maleate, monohexyl maleate, monooctyl maleate, mono-2-maleate Monoalkyl ester of monomer having two carboxyl groups such as ethylhexyl, monomethyl itaconate, monoethyl itaconate, monobutyl itaconate, monoisobutyl itaconate, monohexyl itaconate, monooctyl itaconate, mono-2-ethylhexyl itaconate Compounds: monovinyl compounds of dicarboxylic acids such as monovinyl adipate, monovinyl succinate and monovinyl maleate. These vinyl monomers (a3) can be used alone or in combination of two or more.

  Among the above vinyl monomers (a3), the storage stability of the aqueous fluorocopolymer dispersion of the present invention is further improved, so the number of atoms between the carboxyl group and the vinyl group (carboxyl group and vinyl group) Is not added.) Is preferably a monomer of 4 or more, more preferably in the range of 6-20, and even more preferably in the range of 8-15. As such a vinyl monomer (a3), 3-allyloxypropionic acid (number of atoms between carboxyl group and vinyl group: 4), 10-undecenoic acid (number of atoms between carboxyl group and vinyl group) 8), ω-carboxy-polycaprolactone monoacrylate (having two repeating units of caprolactone; 14 atoms between the carboxyl group and the vinyl group).

  Moreover, you may use the vinyl monomer (a4) which does not have a carboxyl group and a hydroxyl group other than the said vinyl monomers (a2) and (a3) as a raw material of the said 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. By copolymerizing these vinyl monomers (a4) with the vinyl monomers (a2) and (a3), compatibility with other paint components is improved when an aqueous fluorine paint is used. preferable. 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 of the present invention, first, the fluorocopolymer (A) is produced. As a manufacturing method of this fluorine copolymer (A), the following two methods are mentioned, for example.

(Manufacturing method 1)
[First step]
The monomer mixture (I) 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 ( II) is added and a further copolymerization reaction is carried out.

(Manufacturing method 2)
[First step]
A monomer mixture (II) essentially comprising the fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group, and a vinyl monomer (a3) having a carboxyl group is subjected to a copolymerization reaction.
[Second step]
To the reaction product obtained in the first step, the monomer mixture (I) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group is added, and a copolymerization reaction is further performed.

  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.

  In the monomer mixture (I), the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group are essential. In addition, the vinyl monomer (a4) is a monomer. It may be contained in the mixture.

  The amount of each monomer used in the monomer mixture (I) is good in compatibility with other paint components when used as an aqueous fluorine paint, and the weather resistance and chemical resistance of the paint film are good. Therefore, the total amount of the vinyl monomers (a2) and (a4) is preferably in the range of 0.6 to 1.5 mol with respect to 1 mol of the fluoroolefin compound (a1), 0.8 The range of -1.2 mol is more preferable, and the range of 0.9-1.1 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 (I) may contain a vinyl monomer (a3) having a carboxyl group, but the molar ratio in the monomer mixture (I) is 2 mol. % Or less, more preferably 1.5 mol% or less, still more preferably 1 mol% or less.

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

  The amount of each monomer used in the monomer mixture (II) is good in weather resistance and chemical resistance, and when used as an aqueous fluorine paint, compatibility with other paint components is good. Therefore, the total of the vinyl monomers (a2), (a3) and (a4) is preferably in the range of 0.6 to 1.5 mol with respect to 1 mol of the fluoroolefin compound (a1). The range of 8-1.2 mol is more preferable, and the range of 0.9-1.1 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.

  In the monomer mixture (I), when the molar ratio of the vinyl monomer (a2) in the total of the vinyl monomers (a2) and (a4) is less than 100 mol%, In the monomer mixture (II), the total molar ratio of the vinyl monomers (a2) and (a3) in the total of the vinyl monomers (a2), (a3) 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 has good water dispersibility, high storage stability, and a coating film when used as an aqueous fluorine paint. Since the water resistance is also good, the range of 5 to 35 is preferable, the range of 8 to 33 is more preferable, and the range of 10 to 32 is more preferable.

  When the fluororesin aqueous dispersion of the present invention is used in an aqueous fluorocoating compounded with the curing agent (B) described later, the coating film of the coating has excellent mechanical strength, and thus the above production method The range of 20 to 200 is preferable, the range of 30 to 150 is more preferable, and the range of 30 to 120 is more preferable. In addition, the hydroxyl group which a fluorine copolymer (A) has becomes a crosslinking point by reaction of the hardening | curing agent (B) mentioned later.

  Moreover, the weight average molecular weight (Mw) of the fluorine copolymer (A) obtained in the second step of the production methods 1 and 2 has good water dispersibility, high storage stability, and water-based fluorine paint. Since the mechanical strength of the coating film is good, the range is preferably 5,000 to 100,000, more preferably 10,000 to 60,000, and 12,000 to 40,000. A range is further 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.

  The water-based fluorine paint of the present invention contains the above-mentioned fluororesin aqueous dispersion and a curing agent (B) having a functional group that reacts with a hydroxyl group or a carboxy group. The curing agent (B) can be used as a water-based paint together with the fluororesin aqueous dispersion of the present invention, and any compound having a functional group that reacts with a hydroxyl group or a carboxyl group of the fluororesin aqueous dispersion can be used. . Among the curing agents (B), examples of the compound having a functional group that reacts with a hydroxyl group include polyisocyanate compounds, block polyisocyanate compounds, polyepoxy compounds, polycyclocarbonate compounds, amino resins, polycarboxy compounds, and polyhydroxy compounds. A compound, a polyoxazoline compound, a polycarbodiimide compound, etc. are mentioned. Among these, when drying at room temperature such as on-site construction, a water-dispersible polyisocyanate compound is preferable because of its simplicity of use and excellent coating film properties.

  Moreover, since the said hardening | curing agent (B) is mix | blended with a water-based fluorine paint in this invention, what has water dispersibility is preferable. For example, polyisocyanates having water dispersibility include polyisocyanates having hydrophilic groups such as anionic groups, cationic groups, and nonionic groups. Among them, a coating film having excellent water resistance can be obtained. Therefore, a polyisocyanate having a nonionic group as a hydrophilic group is preferred, and specifically, a polyisocyanate having a polyoxyethylene group is preferred. Examples of such water-dispersible polyisocyanates include “Bernock DNW-5500” manufactured by DIC Corporation.

  The curing agent (B) can be used alone or in combination of two or more types, and those having a functional group that reacts with a hydroxyl group and those having a functional group that reacts with a carboxyl group can be used in combination. It is.

  When a polyisocyanate compound is used as the curing agent (B), a coating film having good mechanical strength can be obtained. As the amount used, the isocyanate group (NCO) of the polyisocyanate compound and the fluororesin aqueous A 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 a range in which 0.7 to 1.5 is achieved. 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

Example 1
[First step]
In a stainless steel autoclave substituted with nitrogen inside, 75 parts by mass of diethylene glycol dimethyl ether (hereinafter abbreviated as “MDM”), 144.2 parts by mass of methanol, and ethyl vinyl ether (hereinafter abbreviated as “EVE”) 25 9.9 parts by mass, 4-hydroxybutyl vinyl ether (hereinafter abbreviated as “HBVE”) 26.7 parts by mass, cyclohexyl vinyl ether (hereinafter abbreviated as “CHVE”) 21 parts by mass, light stabilizer (BASF Japan) “Tinuvin 292” manufactured by Co., Ltd., a mixture of bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and methyl (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; Hereinafter, abbreviated as “HALS”.) 16.2 parts by mass and t- They were charged 3.9 parts by chill peroxypivalate. Next, 88.1 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., 264.1 parts by mass of liquefied CTFE was injected over 2.5 hours. Simultaneously with the start of CTFE injection, a mixture consisting of 77.5 parts by weight of EVE, 79.9 parts by weight of HBVE, 63 parts by weight of CHVE, 116.1 parts by weight of MDM, and 11.6 parts by weight of t-butyl peroxypivalate was added for 2.5 hours. Press-fit.

[Second step]
After completion of the monomer injection in the first step, 213.2 parts by mass of liquefied CTFE was continuously injected into the autoclave over 1.5 hours. Also, EVE 54.9 parts by mass, HBVE 53.9 parts by mass, CHVE 1.1 parts by mass, 10-undecenoic acid (hereinafter abbreviated as “UDA”) 107.7 parts by mass, MDM 103.2 parts by mass, and polymerization initiation A mixture consisting of 10.3 parts by mass of t-butyl peroxypivalate as an agent was injected over 2.5 hours. After the press-fitting, 42.2 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 1531.4 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 73.4 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 a 75 mass% solution of the fluorine copolymer (A-1). The acid value of this fluorocopolymer (A-1) was 31.7 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 is put into a 2 liter four-necked flask, heated to 40 ° C., 15.1 parts by mass of dimethylethanolamine is added, and the mixture is stirred for 1 hour to be uniform. After that, the temperature was raised to 60 ° C., and 422.4 parts by mass of ion-exchanged water was gradually added while stirring to obtain an aqueous fluororesin dispersion (1) having a nonvolatile content of 39.3% by mass.

  Regarding the fluororesin aqueous dispersion (1) obtained above, the following storage stability, gel fraction of the coating film, and coating film properties (gloss and pencil hardness) when used in the aqueous fluororesin coating were evaluated.

<Evaluation of storage stability>
The fluororesin aqueous dispersion (1) was stored in a constant temperature bath at 40 ° C., the appearance was visually observed after 1 week, 2 weeks and 4 weeks, and the storage stability was evaluated according to the following criteria.
(Double-circle): There was no generation | occurrence | production of precipitation, gelatinization, and cloudiness.
○: Precipitation did not occur and gelation occurred, but it became slightly cloudy.
(Triangle | delta): It did not reach gelation, but increased viscosity.
X: Generation | occurrence | production of precipitation or gelation occurred.

<Gel fraction of fluororesin aqueous dispersion coating film>
The aqueous fluororesin aqueous dispersion (1) obtained above was applied onto a polypropylene plate and dried at 108 ° C. for 2 hours. The dried coating film was peeled off from the polypropylene plate and weighed, and then immersed in acetone for 24 hours. After the coating film remaining without being dissolved in acetone was dried at 108 ° C. for 2 hours, the percentage obtained by dividing the mass by the mass before being immersed in acetone was defined as the gel fraction.

<Preparation of water-based fluororesin paint and production of coating film>
Aqueous fluororesin dispersion (1) 76.3 parts by mass (30 parts by mass as a fluororesin), 70 parts by mass of titanium oxide (“Taipeku CR-97” manufactured by Ishihara Sangyo Co., Ltd.), and 20.4 parts by mass of ion-exchanged water 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. With respect to 100 parts by mass of this pigment dispersion, 114.5 parts by mass of the fluororesin aqueous dispersion (1), 0.6 parts by mass of a surfactant (“BYK-348” manufactured by Big Chemie Japan Co., Ltd.), an antifoaming agent (San Nopco Co., Ltd. “SN deformer 777”) 0.2 parts by mass and 4 parts by mass of ion-exchanged water were added and mixed uniformly to obtain a paint main agent having a PWC of 40% by mass and a nonvolatile content of 48% by mass. It was. Next, after adding 14.3 parts by mass of a curing agent (“Bernock DNW-5500” manufactured by DIC Corporation, water-dispersible polyisocyanate, non-volatile content 80% by mass) to 100 parts by mass of the paint base, the mixture is uniformly mixed. Thus, an aqueous fluororesin coating material (1) was obtained.

  The aqueous fluororesin paint (1) obtained above is applied to a zinc phosphate-treated steel sheet (JIS G3141 (SPCC-SD) PB-44 manufactured by Nippon Test Panel Co., Ltd.) using an 8 mil (203 μm) applicator. After painting, the film was dried in a thermostatic chamber at 23 ° C. for 7 days to prepare a coating film having a thickness of 50 μm.

<Measurement of glossiness of coating film>
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.

<Measurement of pencil hardness of coating film>
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.

(Example 2)
[First step]
In an autoclave made of stainless steel whose inside is replaced with nitrogen, MDM 75 parts by mass, methanol 144.2 parts by mass, EVE 20.6 parts by mass, HBVE 20.2 parts by mass, CHVE 0.4 parts by mass, UDA 40.4 parts by mass, HALS 16.2 As a polymerization initiator, 3.9 parts by mass of t-butyl peroxypivalate was charged. Next, 80 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., 133.2 parts by mass of liquefied CTFE was injected over 1.5 hours. Simultaneously with the start of CTFE injection, EVE 34.3 parts by mass, HBVE 33.7 parts by mass, CHVE 0.7 parts by mass, UDA 67.3 parts by mass, MDM 64.5 parts by mass, and t-butyl peroxypivalate 6.4 parts by mass The mixture consisting of was pressed over 1.5 hours.

[Second step]
After the completion of the monomer injection in the first step, 352.2 parts by mass of liquefied CTFE was continuously injected into the autoclave over 2.5 hours. Moreover, the mixture which consists of 103.4 mass parts of EVE, 106.6 mass parts of HBVE, 84 mass parts of CHVE, 154.8 mass parts of MDM, and 15.5 mass parts of t-butyl peroxypivalate was press-fitted over 3.5 hours. After the press-fitting, 42.2 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, 74.1 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 a 76.1% by mass solution of the fluorine copolymer (A-2). The acid value of this fluorocopolymer (A-2) was 30.1 mgKOH / g, the number average molecular weight (Mn) was 5,800, and the weight average molecular weight (Mw) was 18,000.

[Third step]
500 parts by mass of the fluorocopolymer solution obtained in the second step is placed in a 2 liter four-necked flask, heated to 40 ° C., 14.6 parts by mass of dimethylethanolamine is added, and the mixture is stirred for 1 hour to be uniform. Then, the temperature was raised to 60 ° C., and 436.7 parts by mass of ion-exchanged water was gradually added while stirring to obtain an aqueous fluororesin dispersion (2) having a nonvolatile content of 39.0% by mass.

  About the fluororesin aqueous dispersion (2) obtained above, it operated similarly to Example 1 and evaluated and measured the storage stability and the gel fraction of the coating film. Further, using the fluororesin aqueous dispersion (2) in an amount of 30 parts by mass as the fluororesin, the same operation as in Example 1 was carried out to prepare an aqueous fluororesin paint (2) to produce a coating film. The film properties (gloss and pencil hardness) were evaluated.

(Example 3)
[First step]
In an autoclave made of stainless steel whose inside is replaced with nitrogen, MDM 75 parts by mass, methanol 144.2 parts by mass, EVE 8.1 parts by mass, HBVE 20.2 parts by mass, CHVE 24.2 parts by mass, UDA 32.3 parts by mass, HALS 16.2 As a polymerization initiator, 3.9 parts by mass of t-butyl peroxypivalate was charged. Next, 76.7 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., 127.9 parts by mass of liquefied CTFE was injected over 1.5 hours. Simultaneously with the start of CTFE injection, EVE 13.4 parts by mass, HBVE 33.7 parts by mass, CHVE 40.4 parts by mass, UDA 53.9 parts by mass, MDM 64.5 parts by mass, and t-butyl peroxypivalate 6.4 parts by mass The mixture consisting of was pressed over 1.5 hours.

[Second step]
After completion of the monomer injection in the first step, 333.9 parts by mass of liquefied CTFE was continuously injected into the autoclave over 2.5 hours. Further, a mixture consisting of 52.8 parts by mass of EVE, 106.6 parts by mass of HBVE, 152.9 parts by mass of CHVE, 154.8 parts by mass of MDM, and 15.5 parts by mass of t-butyl peroxypivalate was injected over 3.5 hours. . After the press-fitting, 42.2 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 1518.8 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 76.8 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 a 75.9 mass% solution of the fluorine copolymer (A-3). The acid value of this fluorocopolymer (A-3) was 25.4 mgKOH / g, the number average molecular weight (Mn) was 5,300, and the weight average molecular weight (Mw) was 19,700.

[Third step]
500 parts by mass of the fluorocopolymer solution obtained in the second step is put into a 2 liter four-necked flask, heated to 40 ° C., 12.2 parts by mass of dimethylethanolamine is added, and the mixture is stirred for 1 hour to be uniform. Then, the temperature was raised to 60 ° C., and 436.6 parts by mass of ion-exchanged water was gradually added with stirring to obtain a fluororesin aqueous dispersion (4) having a nonvolatile content of 39.3% by mass.

  About the fluororesin aqueous dispersion (3) obtained above, it operated similarly to Example 1 and evaluated and measured the storage stability and the gel fraction of the coating film. Also, using the fluororesin aqueous dispersion (3) in an amount of 30 parts by mass as the fluororesin, the same operation as in Example 1 was carried out to prepare an aqueous fluororesin paint (3) to produce a coating film. The film properties (gloss and pencil hardness) were evaluated.

Example 4
[First step]
In an autoclave made of stainless steel whose inside is replaced with nitrogen, MDM 75 parts by mass, methanol 144.2 parts by mass, EVE 28.3 parts by mass, HBVE 20.2 parts by mass, CHVE 2 parts by mass, UDA 26.3 parts by mass, HALS 16.2 parts by mass , And 3.9 parts by mass of t-butyl peroxypivalate as a polymerization initiator was charged. Next, 84.8 parts by mass of liquefied CTFE was injected into the autoclave, and then the autoclave was heated to 63 ° C. Subsequently, 141.4 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, EVE 47.1 parts by mass, HBVE 33.7 parts by mass, CHVE 3.4 parts by mass, UDA 43.7 parts by mass, MDM 64.5 parts by mass, and t-butyl peroxypivalate 6.4 parts by mass The mixture consisting of was pressed over 1.5 hours.

[Second step]
After completion of the monomer injection in the first step, 371.6 parts by mass of liquefied CTFE was continuously injected into the autoclave over 2.5 hours. Further, a mixture comprising 157.2 parts by mass of EVE, 106.6 parts by mass of HBVE, 10.8 parts by mass of CHVE, 154.8 parts by mass of MDM, and 15.5 parts by mass of t-butyl peroxypivalate was press-fitted over 3.5 hours. . After the press-fitting, 42.2 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 1451.8 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 73.0 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 a 77.0% by mass solution of the fluorine copolymer (A-4). It was 19.9 mgKOH / g of this fluorine copolymer (A-4), the number average molecular weight (Mn) was 6,800, and the weight average molecular weight (Mw) was 18,900.

[Third step]
Put 500 parts by mass of the fluorocopolymer solution obtained in the second step into a 2 liter four-necked flask, heat to 40 ° C., add 9.7 parts by mass of dimethylethanolamine, and stir for 1 hour to homogenize. After that, the temperature was raised to 60 ° C., and 452.4 parts by mass of ion-exchanged water was gradually added while stirring to obtain an aqueous fluororesin dispersion (5) having a nonvolatile content of 40.2% by mass.

  About the fluororesin aqueous dispersion (4) obtained above, it operated similarly to Example 1 and evaluated and measured the storage stability and the gel fraction of the coating film. Further, using the fluororesin aqueous dispersion (4) in an amount of 30 parts by mass as the fluororesin, the same operation as in Example 1 was carried out to prepare an aqueous fluororesin paint (4) to produce a coating film. The film properties (gloss and pencil hardness) were evaluated.

(Example 5)
[First step]
In an autoclave made of stainless steel whose inside is replaced with nitrogen, MDM 75 parts by mass, methanol 144.2 parts by mass, EVE 32.3 parts by mass, HBVE 20.2 parts by mass, CHVE 2 parts by mass, UDA 20.2 parts by mass, HALS 16.2 parts by mass , And 3.9 parts by mass of t-butyl peroxypivalate as a polymerization initiator was charged. Next, 86.8 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., 144.7 parts by mass of liquefied CTFE was injected over 1.5 hours. Simultaneously with the start of CTFE injection, EVE 53.9 parts by mass, HBVE 33.7 parts by mass, CHVE 3.4 parts by mass, UDA 33.7 parts by mass, MDM 64.5 parts by mass, and t-butyl peroxypivalate 6.4 parts by mass The mixture consisting of was pressed over 1.5 hours.

[Second step]
After the completion of the press-fitting of the monomer in the first step, 371.5 parts by mass of liquefied CTFE was press-fitted into the autoclave over 2.5 hours. Further, a mixture comprising 157.2 parts by mass of EVE, 106.6 parts by mass of HBVE, 10.8 parts by mass of CHVE, 154.8 parts by mass of MDM, and 15.5 parts by mass of t-butyl peroxypivalate was press-fitted over 3.5 hours. . After the press-fitting, 42.2 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 1463.5 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 74.0 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 a 77.8% by mass solution of the fluorocopolymer (A-5). The acid value of this fluorocopolymer (A-5) was 15.4 mgKOH / g, the number average molecular weight (Mn) was 6,500, 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 is put into a 2 liter four-necked flask, heated to 40 ° C., 7.6 parts by mass of dimethylethanolamine is added, and the mixture is stirred for 1 hour to be uniform. Then, the temperature was raised to 60 ° C., and 464.9 parts by mass of ion-exchanged water was gradually added while stirring to obtain a fluororesin aqueous dispersion (5) having a nonvolatile content of 39.5% by mass.

  About the fluororesin aqueous dispersion (5) obtained above, it operated similarly to Example 1 and evaluated and measured the storage stability and the gel fraction of the coating film. Further, using the fluororesin aqueous dispersion (5) in an amount of 30 parts by mass as the fluororesin, the same operation as in Example 1 was carried out to prepare an aqueous fluororesin paint (5) to produce a coating film. The film properties (gloss and pencil hardness) were evaluated.

(Example 6)
[First step]
In an autoclave made of stainless steel whose inside is replaced with nitrogen, MB 75 parts by mass, methanol 144.2 parts by mass, EVE 36.3 parts by mass, HBVE 20.2 parts by mass, CHVE 2 parts by mass, UDA 13.3 parts by mass, HALS 16.2 parts by mass , And 3.9 parts by mass of t-butyl peroxypivalate as a polymerization initiator was charged. Next, 89.7 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., 149.4 parts by mass of liquefied CTFE was injected over 1.5 hours. Simultaneously with the start of CTFE injection, EVE 60.6 parts by mass, HBVE 33.7 parts by mass, CHVE 3.4 parts by mass, UDA 22.2 parts by mass, MB 64.5 parts by mass, and t-butyl peroxypivalate 6.4 parts by mass The mixture consisting of was pressed over 1.5 hours.

[Second step]
After completion of the monomer injection in the first step, 372.6 parts by mass of liquefied CTFE was continuously injected into the autoclave over 2.5 hours. Further, a mixture comprising 156.2 parts by mass of EVE, 106.6 parts by mass of HBVE, 10.8 parts by mass of CHVE, 154.8 parts by mass of MB, and 15.5 parts by mass of t-butyl peroxypivalate was press-fitted over 3.5 hours. . After completion of this press-fitting, 42.2 parts by mass of MB 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 1484.9 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 75 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 a 75.9 mass% solution of the fluorine copolymer (A-6). The acid value of this fluorocopolymer (A-6) was 10.3 mg KOH / g, the number average molecular weight (Mn) was 6,900, and the weight average molecular weight (Mw) was 19,700.

[Third step]
500 parts by mass of the fluorocopolymer solution obtained in the second step is put into a 2 liter four-necked flask, heated to 40 ° C., 4.9 parts by mass of dimethylethanolamine is added, and the mixture is stirred for 1 hour to be uniform. Then, the temperature was raised to 60 ° C., and 443.8 parts by mass of ion-exchanged water was gradually added while stirring to obtain an aqueous fluororesin dispersion (7) having a nonvolatile content of 40.2% by mass.

  About the fluororesin aqueous dispersion (6) obtained above, it operated similarly to Example 1 and evaluated and measured the storage stability and the gel fraction of the coating film. Moreover, using the fluororesin aqueous dispersion (6) in an amount of 30 parts by mass as the fluororesin, the same operation as in Example 1 was carried out to prepare an aqueous fluororesin paint (6) to produce a coating film. The film properties (gloss and pencil hardness) were evaluated.

(Comparative Example 1)
Fluorine resin having a hydroxyl group (“Fluonate K-700” manufactured by DIC Corporation, nonvolatile content 50% by mass, hydroxyl value of fluororesin 48 mgKOH / g) 280 parts by mass, and methacrylic anhydride 3 The fluororesin which introduce | transduced the methacryloyl group was obtained by charging a mass part and 0.5 mass part of triethylamine, heating up to 80 degreeC, stirring the contents, and stirring for 2 hours, maintaining the same temperature. To 283.5 parts by mass of this fluororesin-introduced fluororesin, uniformly add 6 parts by mass of methacrylic acid, 51 parts by mass of isobutyl methacrylate, and 2.8 parts by mass of t-butylperoxy-2-ethylhexanate. Mix to obtain a mixture. Next, 100 parts by mass of the obtained mixture was put into a four-necked flask purged with nitrogen gas, and the temperature was raised to 80 ° C. While maintaining 80 ° C., the remaining mixture was added dropwise over 4 hours. After completion of the addition, the mixture was further stirred at 80 ° C. for 4 hours to obtain an acrylic-modified fluororesin solution. This acrylic modified fluororesin solution had a nonvolatile content of 57.4% by mass and an acid value of 25.6 mgKOH / g.

  52.3 parts by mass of the acrylic-modified fluororesin solution obtained above (30 parts by mass as an acrylic-modified fluororesin), and a fluororesin having a hydroxyl group (“Fluorate K-700” manufactured by DIC Corporation, nonvolatile content 50% by mass, After charging 140 parts by mass of a fluororesin with a hydroxyl value of 48 mgKOH / g) into a four-necked flask substituted with nitrogen gas, heating to 40 ° C., adding 1 part by mass of dimethylethanolamine, and stirring for 1 hour to make it uniform. The temperature was raised to 60 ° C., and 150 parts by mass of ion-exchanged water was gradually added while stirring to obtain an aqueous dispersion. The obtained aqueous dispersion was concentrated under reduced pressure to obtain a fluororesin aqueous dispersion (R1) having a nonvolatile content of 40.8% by mass.

  About the fluororesin aqueous dispersion (R1) obtained above, the same operation as in Example 1 was carried out, the storage stability, the gel fraction of the coating film, and the coating film characteristics (glossy) when used in the aqueous fluororesin coating material. And pencil hardness).

(Comparative Example 2)
43.6 parts by mass of the acrylic-modified fluororesin solution obtained in Comparative Example 1 (25 parts by mass as the acrylic-modified fluororesin), and a fluororesin having a hydroxyl group (“Fluonate K-700” manufactured by DIC Corporation, non-volatile content 50 masses) %, The hydroxyl value of fluororesin of 48 mg KOH / g) was charged into a four-necked flask in which 150 parts by mass of nitrogen gas was replaced, heated to 40 ° C., 0.7 parts by mass of dimethylethanolamine was added, and the mixture was stirred for 1 hour to be uniform. Then, the temperature was raised to 60 ° C., and 150 parts by mass of ion-exchanged water was gradually added while stirring to obtain an aqueous dispersion. The obtained aqueous dispersion was concentrated under reduced pressure to obtain a fluororesin aqueous dispersion (R2) having a nonvolatile content of 40.2% by mass.

  The fluororesin aqueous dispersion (R2) obtained above was operated in the same manner as in Example 1, and the storage stability and the gel fraction of the coating film were evaluated and measured. Further, using the fluororesin aqueous dispersion (R2) in an amount of 30 parts by mass as the fluororesin, the same operation as in Example 1 was carried out to prepare an aqueous fluororesin paint (R2) to produce a coating film. The film properties (gloss and pencil hardness) were evaluated.

(Comparative Example 3)
In an autoclave made of stainless steel whose inside is replaced with nitrogen, MDM 75 parts by mass, methanol 144.2 parts by mass, EVE 23.7 parts by mass, HBVE 24.1 parts by mass, CHVE 12.8 parts by mass, UDA 16.2 parts by mass, HALS 16.2 As a polymerization initiator, 3.9 parts by mass of t-butyl peroxypivalate was charged. Next, 84.8 parts by mass of liquefied CTFE was injected into the autoclave, and then the autoclave was heated to 63 ° C. Subsequently, 480.6 parts by mass of liquefied CTFE was injected over 4 hours while maintaining the temperature at 63 ° C. Simultaneously with the start of CTFE injection, EVE 134.6 parts by mass, HBVE 136.3 parts by mass, CHVE 72.3 parts by mass, UDA 91.5 parts by mass, MDM 236.2 parts by mass, and t-butyl peroxypivalate 21.9 parts by mass The mixture consisting of was pressed over 5 hours.

  After reacting for 12 hours from the start of CTFE injection, the internal pressure of the autoclave was returned to normal pressure, and 1375 parts by mass of the reaction product was recovered. The obtained solution was put into a 3 liter four-necked flask, 75 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 concentrated under reduced pressure to obtain a 74.1% by mass solution of a fluorocopolymer (RA-1). The acid value of this fluorocopolymer (RA-1) was 30.0 mgKOH / g, the number average molecular weight (Mn) was 5,400, and the weight average molecular weight (Mw) was 14,300.

  500 parts by mass of the fluorocopolymer solution (RA-1) was placed in a 2 liter four-necked flask, heated to 40 ° C., 13.7 parts by mass of dimethylethanolamine was added, and the mixture was stirred for 1 hour to make it uniform. Thereafter, the temperature was raised to 60 ° C., and 448.6 parts by mass of ion-exchanged water was gradually added while stirring to obtain a fluororesin aqueous dispersion (R3) having a nonvolatile content of 38.2% by mass.

  About the fluororesin aqueous dispersion (R3) obtained above, it operated similarly to Example 1 and evaluated and measured the storage stability and the gel fraction of the coating film. Further, using the fluororesin aqueous dispersion (R3) in an amount of 30 parts by mass as the fluororesin, the same operation as in Example 1 was carried out to prepare an aqueous fluororesin paint (R3) to produce a coating film. The film properties (gloss and pencil hardness) were evaluated.

  Table 1 shows the composition, acid value, number average molecular weight, and weight average molecular weight of the fluorine copolymer monomers produced in Examples 1 to 6 and Comparative Example 3 described above. Table 2 shows the results of evaluating the storage stability of the fluororesin aqueous dispersion, the gel fraction of the coating film, and the coating film properties (gloss and pencil hardness) when the fluororesin aqueous dispersion was used in the aqueous fluororesin coating. Shown in

  From the evaluation results of Examples 1 to 6 shown in Table 2, the aqueous fluororesin dispersion of the present invention has very excellent storage stability, and the aqueous fluorocoating material using the aqueous fluororesin dispersion The coating film characteristics were also good.

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

  Comparative Example 1 is an example using a fluororesin aqueous dispersion described in Patent Document 3, but the coating properties of the aqueous fluorocoating using the fluororesin aqueous dispersion were relatively good. However, it turned out that it is inferior to storage stability.

  Comparative Example 2 is an example using an equivalent of the fluororesin aqueous dispersion described in Patent Document 3, but the coating properties of the aqueous fluorocoating using the fluororesin aqueous dispersion were relatively good. However, it turned out that it is inferior to storage stability.

  Comparative Example 3 is an example in which the monomer composition corresponding to Example 2 was used, and the copolymerization reaction was performed in one step without performing the copolymerization reaction in two steps of the first step and the second step. The coating properties of the aqueous fluorine paint using the aqueous fluororesin dispersion were relatively good, but the storage stability was poor.

Claims (8)

A first step of copolymerizing a monomer mixture (I) essentially comprising a fluoroolefin compound (a1) and a vinyl monomer (a2) having a hydroxyl group;
Monomer mixture (II) in which the reaction product obtained in the first step essentially comprises a fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group and a vinyl monomer (a3) having a carboxyl group. ) And further copolymerization reaction to obtain a fluorine copolymer (A),
A fluorocopolymer aqueous dispersion obtained by a third step of neutralizing a carboxyl group of the fluorocopolymer (A) with a basic compound and dispersing in a water medium. A first step of copolymerizing a monomer mixture (II) essentially comprising a fluoroolefin compound (a1), a vinyl monomer (a2) having a hydroxyl group and a vinyl monomer (a3) having a carboxyl group;
To the reactant obtained in the first step, the monomer mixture (I) essentially comprising the fluoroolefin compound (a1) and the vinyl monomer (a2) having a hydroxyl group is added, and further copolymerized, A second step of obtaining a fluorine copolymer (A),
A fluororesin aqueous dispersion obtained by a third step of neutralizing a carboxyl group of the fluorocopolymer (A) with a basic compound and dispersing in a water medium.   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 fluororesin aqueous dispersion according to claim 1 or 2.   The amount of each monomer used in the monomer mixture (I) is 0.000 in total of the vinyl monomers (a2) and (a4) with respect to 1 mol of the fluoroolefin compound (a1). 6-1.5 mol, the molar ratio of the vinyl monomer (a2) in the total of the vinyl monomers (a2) and (a4) is in the range of 10-100 mol%, The amount of each monomer used in the monomer mixture (II) 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 from 10 to 97 mol. The vinyl resin in the total of the vinyl monomers (a2), (a3) and (a4) The molar ratio of the monomer (a3), and a fluorine resin aqueous dispersion according to claim 3, wherein in the range of 3 to 60 mol%.   The fluororesin aqueous dispersion according to claim 1, wherein the vinyl monomer (a3) is a monomer having 4 or more atoms between a carboxyl group and a vinyl group.   6. A water-based fluoro paint comprising the fluororesin aqueous dispersion according to claim 1 and a curing agent (B) having a functional group that reacts with a hydroxyl group or a carboxy group.   The water-based fluorine paint according to claim 6, wherein the curing agent (B) is a polyisocyanate compound.   An article coated with the water-based fluorine paint according to claim 6 or 7.