JP2013001756A - Aqueous coating material composition and two-pack curable aqueous coating material kit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous coating material composition which excels in the external appearance of a coating film and further has a long pot life and a two-pack curable aqueous coating material kit.SOLUTION: The aqueous coating material composition includes a fluorine-containing copolymer (A) which is a fluorine-containing copolymer having a hydroxyl group, a compound (B) which is a compound having a sulfo group or a partially or entirely neutralized sulfo group and more than one isocyanate group, and an aqueous medium (C).

Description

  The present invention relates to an aqueous coating composition containing a fluorine-containing copolymer and a two-component curable aqueous coating kit.

In recent years, in order to protect the natural environment, pollution such as global warming and photochemical smog due to organic solvent emissions has become a problem, and emission regulations are being implemented. In Europe, regulations are ahead, and in Japan, the Air Pollution Control Law was revised in 2006, and legal emission regulations were started.
In order to comply with legal regulations, in the paint field, the development of a coating method that increases the coating efficiency and effectively uses the paint, and the introduction of high-solid paint that increases the solid content concentration of the paint and reduces the solvent discharged Has been implemented. However, there is a limit to solvent reduction in high solid paints.

  Aqueous paint compositions in which various synthetic resins such as alkyd, acrylic, polyester, polyvinyl acetate, and epoxy are dispersed or dissolved in water are known. An aqueous coating composition using a crosslinkable fluorine-containing copolymer having a hydroxyl group as a synthetic resin or as part of a synthetic resin is widely used because of its excellent weather resistance.

  As the fluorine-containing copolymer, there is a fluorine-containing copolymer in which a carboxyl group is introduced in an organic solvent and neutralized with a basic compound in part or all of the carboxyl group in order to increase the affinity for water. Are known. Polyether-modified isocyanate is employed as a curing agent for the copolymer (Patent Documents 1 and 2). A fluorine-containing copolymer obtained by emulsion polymerization is also known, and in this case as well, polyether-modified isocyanate is employed as a curing agent (Patent Document 3).

  However, when the aqueous dispersion or aqueous solution of the fluorine-containing copolymer described in Patent Documents 1 to 3 is cured using polyether-modified isocyanate, the water of the fluorine-containing copolymer of polyether-modified isocyanate that is a curing agent is used. Dispersibility in a dispersion or aqueous solution was poor, and there was a problem that fish eyes were generated in the coating film. In addition, the aqueous dispersion or aqueous solution of the fluorinated copolymer has a problem that the time for maintaining a paintable state (that is, pot life) is short after mixing the curing agent.

International Publication No. 2004/072197 Pamphlet International Publication No. 2007/125970 Pamphlet JP 7-324180 A

  The present invention relates to an aqueous coating composition that solves the above-mentioned problems. That is, an object of the present invention is to provide an aqueous coating composition and a two-part curable aqueous coating kit that have excellent coating film appearance and a long pot life.

The present invention has the following configuration.
[1] An aqueous coating composition containing the following fluorinated copolymer (A), the following compound (B), and an aqueous medium (C).
Fluorine-containing copolymer (A): a fluorine-containing copolymer having a hydroxyl group.
Compound (B): A compound having a sulfo group or a sulfo group partially or wholly neutralized and more than one isocyanate group.

[2] The fluorine-containing copolymer (A) includes a polymer unit based on a fluoroolefin and a polymer unit having a hydroxyl group, and the hydroxyl value is 20 to 150 mgKOH / g [1] ] The composition for water-based coatings of description.
[3] The fluorine-containing copolymer (A) further contains a polymer unit having an acid group or an acid group partially or wholly neutralized, and the acid value exceeds 0 mgKOH / g and 40 mgKOH / The composition for water-based paint according to [2], wherein the composition is g or less.

（ただし、式（２）中、Ｒ^２ｂは水素原子またはメチル基、Ｒ^２ｃは炭素数１〜１０のアルキレン基または炭素数４〜１０の２価の脂環式基である。ｍは０〜８の整数、ｎは０または１である。）

（ただし、式（３）中、Ｒ^３ｂは水素原子またはメチル基、Ｒ^３ｃは、炭素数１〜１０のアルキレン基または炭素数４〜１０の２価の脂環式基、Ｒ^３ｄは炭素数２〜１０のアルキレン基、またはエチレン性二重結合を１以上有する炭素数２〜１０の２価の炭化水素基、炭素数４〜１０の２価の脂環式基、または炭素数４〜１０の２価の芳香族基、Ｒ^３ｅは水素原子または−ＮＨＺ^１Ｚ^２Ｚ^３（Ｚ^１、Ｚ^２、およびＺ^３はそれぞれ独立に、水素原子、炭素数１〜４のアルキル基、または炭素数１〜６のヒドロキシアルキル基である。）である。ｐは０〜８の整数、ｑは０または１である。）

（ただし、式（４）において、Ｒ^４ｂは水素原子またはメチル基、Ｒ^４ｅは炭素数１〜１２のアルキル基または炭素数４〜１０の１価の脂環式基である。ｊは０〜８の整数、ｋは０または１である。） [4] The fluorine-containing copolymer (A) is a polymer unit based on a fluoroolefin, a polymer unit represented by the following formula (2), a polymer unit represented by the following formula (3), and the following formula (4) The ratio of the polymerized units based on fluoroolefin to the total polymerized units in the fluorine-containing copolymer (A) is 40 to 60 mol%, and is represented by the following formula (4). The composition for water-based paints as described in [3] whose ratio of the polymerized unit is 3-50 mol%.

(In the formula (2), R ^2b is a hydrogen atom or a methyl group, R ^2c is an alkylene group having 1 to 10 carbon atoms or a divalent alicyclic group having 4 to 10 carbon atoms. An integer of 8 and n is 0 or 1.)

(In the formula (3), R ^3b is a hydrogen atom or a methyl group, R ^3c is an alkylene group having 1 to 10 carbon atoms or a divalent alicyclic group having 4 to 10 carbon atoms, and R ^3d is a carbon number. An alkylene group having 2 to 10 carbon atoms, a divalent hydrocarbon group having 2 to 10 carbon atoms having one or more ethylenic double bonds, a divalent alicyclic group having 4 to 10 carbon atoms, or 4 to 10 carbon atoms Divalent aromatic group, R ^3e is a hydrogen atom or —NHZ ¹ Z ² Z ³ (Z ¹ , Z ² and Z ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or carbon (It is a hydroxyalkyl group of the number 1-6.) P is an integer of 0-8, q is 0 or 1.)

(In the formula (4), R ^4b is a hydrogen atom or a methyl group, R ^4e is an alkyl group having 1 to 12 carbon atoms or a monovalent alicyclic group having 4 to 10 carbon atoms. (An integer of 8 and k is 0 or 1.)

[5] The compound (B) is a compound obtained by reacting a polyisocyanate having two or more isocyanate groups with aminosulfonic acid so that the isocyanate groups remain in a ratio exceeding 1. [1] to [1] [4] The composition for water-based paints according to any one of [4].
[6] The aqueous coating composition according to [5], wherein the aminosulfonic acid is at least one selected from 2- (cyclohexylamino) ethanesulfonic acid and 3- (cyclohexylamino) propanesulfonic acid.
[7] The aqueous coating composition according to any one of [1] to [6], wherein the number of isocyanate groups of the compound (B) is 1.8 or more.
[8] The number of isocyanate groups contained in the compound (B) is 2.0 to 4.8, and the proportion of isocyanate groups in the molecular weight in the compound (B) is 4.0 to 26.0% by mass. There, a sulfonate group ratio of (where mass calcd SO ₃ group) is 0.1 to 7.7 mass% [1] ~ aqueous coating composition according to any one of [7].

Moreover, one embodiment of the two-component curable aqueous paint kit of the present invention has the following configuration.
[9] A main agent (D) containing the fluorine-containing copolymer (A) and the aqueous medium (C), and a curing agent (E) containing the compound (B), or the fluorine-containing copolymer ( A) Main agent (D) containing an aqueous medium (C1) and a curing agent (E) containing the compound (B) and a medium (C2) not containing water (however, the aqueous medium (C1) and the medium ( C2) is combined to form the aqueous medium (C).) The aqueous coating material according to any one of [1] to [8] by combining the main agent (D) and the curing agent (E). A two-part curable water-based paint kit characterized by forming a composition.

  The aqueous paint composition and the two-component curable aqueous paint kit of the present invention have a long pot life. Moreover, the coating film formed from the composition for water-based paints of this invention is excellent in an external appearance.

In the present specification, the polymerization unit refers to the minimum repeating unit formed by a polymerization reaction of a compound having a polymerizable reactive group (the compound is also referred to as a monomer or a monomer).
In this specification, the primary amino group refers to a group represented by —NH _{2 in} which one hydrogen atom of a primary amine (NH ₃ ) serves as a bond, and the secondary amino group refers to —NH ₂ . A monovalent group in which one hydrogen atom becomes a monovalent hydrocarbon group (for example, an alkyl group or the like).

[Composition for water-based paint]
The aqueous coating composition of the present invention contains the following fluorinated copolymer (A), the following compound (B), and an aqueous medium (C).

Fluorine-containing copolymer (A): a fluorine-containing copolymer having a hydroxyl group.
Compound (B): A compound having a sulfo group or a sulfo group partially or wholly neutralized and more than one isocyanate group.

<Fluorine-containing copolymer (A)>
The fluorine-containing copolymer (A) is a fluorine-containing copolymer having a hydroxyl group. The fluorine-containing copolymer (A) is preferably a polymer essentially comprising a polymer unit of a monomer essentially comprising a fluorine atom and a polymer unit of a monomer essentially comprising a hydroxyl group, and further a polymer other than the above polymerized unit. A polymer containing a unit (hereinafter referred to as other polymerized unit) is particularly preferred.

The fluorine-containing copolymer (A) is preferably a polymer containing a polymerization unit based on a fluoroolefin as a polymerization unit of a monomer essentially containing a fluorine atom. Furthermore, the fluorine-containing copolymer (A) contains a polymer unit having a hydroxyl group, and the hydroxyl value is particularly preferably 20 to 150 mgKOH / g.
As the polymer unit based on the fluoroolefin, a polymer unit represented by the following formula (1) (hereinafter, the polymer unit is referred to as polymer unit (1). The polymer units represented by other formulas are also represented similarly). Is preferred.

^{-CX 1 X 2 -CX 3 X 4} - (1)
(However, in Formula (1), X < ¹ >, X < ² >, X < ³ > and X < ⁴ > are respectively independently a C1-C3 alkyl group which has a hydrogen atom, a chlorine atom, a fluorine atom, an alkyl group, or a halogen atom. And at least one of X ^{1 to} X ⁴ is a fluorine atom or an alkyl group having 1 to 3 carbon atoms having a fluorine atom.)

As monomers for forming the polymerized unit (1), CF ₂ = CF ₂ , CClF = CF ₂ , CHCl = CF ₂ , CCl ₂ = CF ₂ , CClF = CClF, CHF = CCl ₂ , CH ₂ = CClF, CCl ₂ = fluoroethylene such as _{CClF; CF 3 CH = CF 2} , CF 2 ClCF = CF 2, CF 3 CCl = CF 2, CF 3 CF = CFCl, CF 2 ClCCl = CF 2, CF 2 ClCF = CFCl, CFCl 2 CF = CF ₂ , CF ₃ CCl = CClF, CF ₃ CCl = CCl ₂ , CClF ₂ CF = CCl ₂ , CCl ₃ CF = CF ₂ , CF ₂ ClCCl = CCl ₂ , CFCl ₂ CCl = CCl ₂ , CF ₃ CF = _{CHCl, CClF 2 CF = CHCl,} CHF 2 CCl = CCl 2, CF 2 ClCH = _{Cl 2, CF 2 ClCCl = CHCl} , CCl 3 CF = CHCl, CH 2 BrCF = fluoropropenes such as _{CCl 2; CF 3 CCl = CFCF} 3, CF 2 = CFCF 2 CClF 2, CF 3 CF 2 CF = CCl 2 Examples thereof include a fluoroolefin compound having 4 or more carbon atoms, and the like.

  As the monomer for forming the polymerization unit (1), fluoroethylenes, fluoropropenes and the like are preferable. As the fluoroethylenes, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and the like are preferable, and as the fluoropropenes, hexafluoropropylene and the like are preferable. When the fluorine-containing copolymer (A) has these polymerized units (1), there is an advantage that the coating film has excellent weather resistance.

  The fluorine-containing copolymer (A) is preferably a polymer essentially comprising a polymer unit of a monomer essential for the fluorine atom and a polymer unit of a monomer essential for a hydroxyl group. The preferable aspect of the polymerization unit of the monomer which has this hydroxyl group as essential is mentioned later. Furthermore, the fluorinated copolymer (A) is preferably a polymer containing a hydroxyl group in such an amount that the hydroxyl value is 20 to 150 mgKOH / g. Here, the hydroxyl value is an index indicating the hydroxyl group content. In the fluorine-containing copolymer (A) used in the present invention, the hydroxyl value is 40 to 40 from the viewpoint of adjusting the crosslinking density to an appropriate range. 125 mgKOH / g is preferable, and 40 to 60 mgKOH / g is particularly preferable. The hydroxyl value can be quantified by the method shown in the Examples.

The fluorine-containing copolymer (A) includes, as other polymerized units, polymer units having acid groups or partially or wholly neutralized acid groups, and the acid value thereof exceeds 0 mgKOH / g and 40 mgKOH / g. More preferably, it is g or less.
The polymer unit having an acid group or a partially or wholly neutralized acid group is a polymer unit having a carboxyl group as an acid group or a group in which a part or all of the carboxyl group is neutralized. preferable. A preferred embodiment of the polymerized unit will be described later.
Here, the acid value indicates the content of acid groups and (in the present invention, neutralized acid groups) in the copolymer. The acid value of the fluorinated copolymer (A) is a value determined from the total amount of acid groups and neutralized acid groups. The acid value can be quantified by the method shown in the Examples.

  As the fluorine-containing copolymer (A), a polymer containing neither an acid group nor a neutralized acid group may be used. In this case, the acid value of the polymer is 0 mgKOH / g. In the present invention, the fluorine-containing copolymer (A) is preferably a polymer having the above acid value from the viewpoint of solubility or dispersibility in water and stability in water, and the acid value is preferably 7 to 25 mgKOH. / G is more preferable, and 10 to 20 mg KOH / g is particularly preferable.

As the fluorine-containing copolymer (A), the polymer unit (1) as a polymer unit based on a fluoroolefin, a polymer unit represented by the following formula (2), a polymer unit represented by the following formula (3), and And a fluorine-containing copolymer containing a polymer unit represented by the following formula (4).
The proportion of each polymer unit in the copolymer is preferably 40 to 60 mol% of the polymer unit (1) and 3 to 50 mol% of the polymer unit (4). As a ratio of the above-mentioned polymerization unit (2) and polymerization unit (3) in the copolymer, a ratio in which the hydroxyl value and the acid value are the above values is preferable.

  40-60 mol% is preferable and, as for the content rate of the polymerization unit (1) with respect to all the polymerization units in a fluorine-containing copolymer (A), 45-55 mol% is more preferable. When the content ratio of the polymer units (1) in the fluorinated copolymer (A) is within this range, sufficient weather resistance is obtained, and the glass transition temperature of the fluorinated copolymer (A) does not become too high, An amorphous film having a good appearance can be obtained.

  The polymer unit having a hydroxyl group is preferably a polymer unit represented by the following formula (2).

（ただし、式（２）中、Ｒ^２ｂは水素原子またはメチル基、Ｒ^２ｃは炭素数１〜１０のアルキレン基または炭素数４〜１０の２価の脂環式基である。ｍは０〜８の整数、ｎは０または１である。）

(In the formula (2), R ^2b is a hydrogen atom or a methyl group, R ^2c is an alkylene group having 1 to 10 carbon atoms or a divalent alicyclic group having 4 to 10 carbon atoms. An integer of 8 and n is 0 or 1.)

  The polymerization unit (2) is preferably a polymerization unit based on a hydroxyl group-containing vinyl ether, a hydroxyl group-containing vinyl ester, a hydroxyl group-containing allyl ether, or a hydroxyl group-containing allyl ester, and is based on a hydroxyalkyl vinyl ether or the like from the viewpoint of polymerizability and crosslinkability. Polymerized units are more preferred. Moreover, as a monomer which forms a polymerization unit (2), 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, 1-hydroxymethyl-4-vinyloxymethylcyclohexane, 4-hydroxyptyl vinyl ester, etc. are preferable. .

  4-30 mol% is preferable, as for the content rate of the polymerization unit (2) with respect to all the polymerization units in a fluorine-containing copolymer (A), 8-25 mol% is more preferable, and 8-12 mol% is especially preferable.

  As the polymer unit having an acid group or an acid group partially or wholly neutralized, a polymer unit represented by the following formula (3) is preferable.

（ただし、式（３）中、Ｒ^３ｂは水素原子またはメチル基、Ｒ^３ｃは、炭素数１〜１０のアルキレン基または炭素数４〜１０の２価の脂環式基、Ｒ^３ｄは炭素数２〜１０のアルキレン基、またはエチレン性二重結合を１以上有する炭素数２〜１０の２価の炭化水素基、炭素数４〜１０の２価の脂環式基、または炭素数４〜１０の２価の芳香族基、Ｒ^３ｅは水素原子または−ＮＨＺ^１Ｚ^２Ｚ^３（Ｚ^１、Ｚ^２、およびＺ^３はそれぞれ独立に、水素原子、炭素数１〜４のアルキル基、または炭素数１〜６のヒドロキシアルキル基である。）である。ｐは０〜８の整数、ｑは０または１である。）

(In the formula (3), R ^3b is a hydrogen atom or a methyl group, R ^3c is an alkylene group having 1 to 10 carbon atoms or a divalent alicyclic group having 4 to 10 carbon atoms, and R ^3d is a carbon number. An alkylene group having 2 to 10 carbon atoms, a divalent hydrocarbon group having 2 to 10 carbon atoms having one or more ethylenic double bonds, a divalent alicyclic group having 4 to 10 carbon atoms, or 4 to 10 carbon atoms Divalent aromatic group, R ^3e is a hydrogen atom or —NHZ ¹ Z ² Z ³ (Z ¹ , Z ² and Z ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or carbon (It is a hydroxyalkyl group of the number 1-6.) P is an integer of 0-8, q is 0 or 1.)

As the polymerized unit (3), when R ^3e in the case of a polymer unit having an acid group is a hydrogen atom (that is, the polymer unit (3) is a polymer unit having a carboxyl group), a neutralized acid In the case where R ^3e in the case of a group is —NHZ ¹ Z ² Z ³ (that is, the polymerized unit (3) is a polymerized unit having a carboxylic acid group) is preferred.

Polymerization unit (3) is a polymerization in which p is 0, q is 0, R ^3c is an alkylene group having 2 to 8 carbon atoms, R ^3d is an alkylene group having 2 to 8 carbon atoms, and R ^3e is a trialkylamino group A unit is preferable, and from the viewpoints of polymerizability, crosslinkability and the like, a polymer unit in which p is 0, q is 0, R ^3c is a butylene group, R ^3d is an ethylene group, and R ^3e is a triethylamino group is more preferable.
The proportion of the carboxylate group in the total amount of the carboxyl group and the carboxylate group is preferably 30 to 100 mol%, more preferably 70 to 100 mol%, and 100 mol% (that is, the polymerization unit (3) is only the carboxylate group). Is more preferable.

  By adjusting the proportion of the carboxylate group in the polymerization unit (3), the fluorinated copolymer (A) can keep the dispersed particle size in water small even if the acid value is small. The storage stability (especially storage stability when various dispersion / dissolving components are blended) is improved.

When the polymer unit (3) has a carboxylate group, the group represented by the formula —COONHZ ¹ Z ² Z ³ in the polymer unit is a cationic component (that is, N ⁺ HZ in the aqueous coating composition). ¹ Z ² Z cation represented by ³⁾ and anionic groups (i.e., formula -COO ^- may be dissociated into groups) represented by..

The following method is mentioned as a manufacturing method of a polymerization unit (3).
(Method i) A method of copolymerizing a monomer having a carboxylate group.
(Method ii) A method of neutralizing a carboxyl group with a basic compound such as amines after copolymerizing a monomer having a carboxyl group.
(Method iii) Polymerization of a monomer containing a hydroxyl group, followed by esterification with a dicarboxylic acid represented by the formula HOOC-R ^3d -COOH or an anhydride thereof, and then the terminal carboxyl group with a base such as an amine Neutralizing with a functional compound.

When the method iii is employed, the monomer containing a hydroxyl group can be the same monomer as the monomer for forming the polymerized unit (2), and is similar from the viewpoint of ease of production. Monomers are preferred.
Further, as dicarboxylic anhydrides, succinic anhydride, glutaric anhydride, itaconic anhydride, adipic anhydride, 1,2-cyclohexanedicarboxylic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, phthalic anhydride 1,8-naphthalic anhydride, maleic anhydride and the like. Examples of the dicarboxylic acid include a reaction product of dicarboxylic anhydride and water.

The content ratio of the polymer units (3) is preferably more than 0 mol% and not more than 8 mol%, more preferably 1.4 to 5 mol%, based on all the polymerized units of the fluorinated copolymer (A). More preferably, it is 4 mol%.
When the content ratio of the polymerization unit (3) is the above ratio, the fluorine-containing copolymer (A) can improve the dispersibility in water and the stability in water. Therefore, the storage stability of the composition for water-based paints can be secured, and the water resistance when a coating film is formed can be secured.

  Furthermore, the fluoropolymer (A) of the present invention is preferably a polymer having a polymer unit represented by the following polymer unit (4) as another polymer unit.

（ただし、式（４）において、Ｒ^４ｂは水素原子またはメチル基、Ｒ^４ｅは炭素数１〜１２のアルキル基または炭素数４〜１０の１価の脂環式基である。ｊは０〜８の整数、ｋは０または１である。）

(In the formula (4), R ^4b is a hydrogen atom or a methyl group, R ^4e is an alkyl group having 1 to 12 carbon atoms or a monovalent alicyclic group having 4 to 10 carbon atoms. (An integer of 8 and k is 0 or 1.)

  The polymer units (4) represented by the above formula (4) include alkyl vinyl ether polymer units (j and k are 0), alkyl vinyl ester polymer units (j is 0, k is 1), and alkyl allyl ether polymers. It is preferably a polymer unit selected from a unit (j is 1, k is 0) and an alkylallyl ester polymer unit (j is 1, k is 1).

  As the monomer for forming the polymerization unit (4), ethyl vinyl ether, n-butyl vinyl ether, cyclohexyl vinyl ether, vinyl acetate, vinyl valerate, vinyl pivalate, etc. are preferable, and film properties (hardness, gloss, pigment dispersion) It is preferable to select and adopt as appropriate according to the property.

  As the monomer for forming the polymer unit (4), ethyl vinyl ether, cyclohexyl vinyl ether, and the like are preferable because they have good alternating copolymerization with a fluoroolefin and can easily adjust the glass transition temperature.

  3-50 mol% is preferable with respect to all the polymerization units of a fluorine-containing copolymer (A), and, as for the content rate of a polymerization unit (4), 20-45 mol% is more preferable.

  Each of the polymer units (1) to (4) in the fluorinated copolymer (A) may be one kind or two or more kinds. The total amount of the polymerized units (1) to (4) in the fluorinated copolymer (A) is preferably 80 to 100 mol%, more preferably 95 to 100 mol%, more preferably 100 mol% based on all polymerized units. Is more preferable.

  When the fluorinated copolymer (A) contains polymerized units other than the polymerized units (1) to (4) (hereinafter referred to as polymerized units (5)), all polymerized units of the fluorinated copolymer (A). The ratio of the polymerized unit (5) to is preferably less than 20 mol%, and more preferably less than 5 mol%.

  The polymerized unit (5) is preferably a polymerized unit having no crosslinkable functional group, particularly preferably a polymerized unit based on a non-fluorinated ethylenic monomer, such as ethylene, propylene, n-butene and isobutene. Examples thereof include polymerized units obtained by polymerizing fluorine-based olefins.

  The particularly preferred constitution of the fluorinated copolymer (A) used in the present invention is 45 to 55 mol% of the polymer unit (1), 8 to 25 mol% of the polymer unit (2), and 1. The composition is 4 to 5 mol%, the polymerization unit (4) is 20 to 45 mol%, and does not contain the polymerization unit (5).

  The mass average molecular weight of the fluorinated copolymer (A) is preferably from 3,000 to 200,000. The molecular weight (mass average molecular weight and number average molecular weight) in the present specification is a value measured by gel permeation chromatography using polystyrene as a standard. By making the mass average molecular weight within this range, the paintability of the coating composition is improved, and the weather resistance of the coating film and the coating film appearance are also improved.

<Production of fluorinated copolymer (A)>
The fluorine-containing copolymer (A) in the present invention can be produced by a method in which a monomer that forms a desired polymerization unit is polymerized by a known polymerization method. In the polymerization reaction, a polymerization catalyst, a polymerization initiator, or a polymerization initiation source such as ionizing radiation may be used as necessary. In particular, the copolymerization reaction in the present invention is preferably performed in the presence of a basic compound in order to keep the reaction system on the alkali side.

  As the polymerization initiator, peroxy ester type peroxides such as t-butyl peroxyacetate; dialkyl peroxydicarbonates such as diisopropyl peroxydicarbonate can be used. Besides, benzoyl peroxide, azobisiso Examples include butyronitrile.

  The basic compound can be selected from an organic basic compound and an inorganic basic compound. As the organic basic compound, alkylamines such as triethylamine and alkylphosphines such as triethylphosphine are preferable. Among the inorganic basic compounds, carbonates, hydroxides or oxides of alkali metals or alkaline earth metals such as potassium carbonate, potassium hydroxide, sodium hydroxide and magnesium oxide are preferable.

  The usage-amount of a polymerization initiator can be suitably changed according to a kind and copolymerization reaction conditions, Usually, about 0.05-0.5 mass part is preferable with respect to the monomer whole quantity. 0.01-20 mass parts is preferable with respect to the monomer whole quantity, and, as for the usage-amount of a basic compound, 0.1-10 mass parts is especially preferable.

As the copolymerization reaction, solution polymerization, emulsion polymerization, suspension polymerization and the like can be adopted, and the use of solution polymerization is particularly preferable. As the solvent used for the solution polymerization, alcohols, esters, ketones, saturated halogenated hydrocarbons containing one or more fluorine atoms, aromatic hydrocarbons such as xylene are preferably used.
The reaction temperature of the copolymerization reaction is preferably 10 ° C to 90 ° C. The reaction pressure is preferably ^{0~100kg / cm 2 · G, 1~50kg} / cm 2 · G is more preferable.

  As a method for producing the fluorinated copolymer (A) containing the polymerized unit (1), polymerized unit (2), polymerized unit (3), and polymerized unit (4), monomers forming the respective polymerized units are used. The method of copolymerizing is mentioned. Furthermore, for the polymerized unit (3), the above method i to method iii can be adopted, and the method iii is preferable.

As a preferred example of the method for producing the fluorinated copolymer (A), first, a fluorinated copolymer obtained by copolymerizing monomers respectively forming the polymerized unit (1), the polymerized unit (2) and the polymerized unit (4). Copolymer (X) is obtained. Here, the fluorine-containing copolymer (X) is a fluorine-containing copolymer that can be used as the fluorine-containing copolymer (A) in the present invention, and other than the polymerization units (1) to (4) and the polymerization units. In the production of a fluorine-containing copolymer (A) containing the above polymerized units, it is used as an intermediate. The blending amount of each monomer is preferably the same amount as the mol% of the desired polymerized unit for the monomer forming the polymerized unit (1) and the polymerized unit (4). The polymerization unit (2) is preferably the same amount as the total mol% of the polymerization unit (2) and the polymerization unit (3).
For the copolymerization, a polymerization initiator, a basic compound, a solvent, and the like can be used. The type, amount used, reaction conditions for the copolymerization, and the like are the same as described above.

  Commercially available products can be used as the fluorinated copolymer (X). Examples of commercially available products include Lumiflon (trade name, manufactured by Asahi Glass Co., Ltd.), Zeffle (trade name, manufactured by Daikin Corp.), and the like.

  Next, the hydroxyl group of the fluorine-containing copolymer (X) is esterified to form a polymer unit (3). The ratio of esterification is adjusted according to the ratio of polymerized units (2) and (3).

  The esterification is preferably performed by reacting the fluorinated copolymer (X) with a dicarboxylic anhydride in an organic solvent. By the esterification, the polymer unit (2) can be converted into a polymer unit (3) in which the hydroxyl group contains a carboxyl group.

  Dicarboxylic acid anhydrides include succinic anhydride, glutaric anhydride, itaconic anhydride, adipic anhydride, 1,2-cyclohexanedicarboxylic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, phthalic anhydride, 1,8-naphthalic anhydride, maleic anhydride and the like are preferable.

  As the organic solvent, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, methyl cellosolve, ethyl cellosolve, isopropyl cellosolve, butyl cellosolve, Cellosolves such as secondary butyl cellosolve, propylene glycol derivatives such as propylene glycol methyl ether, dipropylene glycol methyl ether and propylene glycol methyl ether acetate, ketones such as ethylene glycol ethyl ether acetate, acetone, methyl ethyl ketone and methyl isobutyl ketone, toluene And aromatic compounds such as xylene. The organic solvent can be appropriately selected from the viewpoint of solubility of the fluorinated copolymer (X) and the dicarboxylic acid anhydride.

The esterification may be carried out in the presence of a catalyst. As the catalyst, carboxylic acid metal salts, alkali hydroxides, alkali metal carbonates, quaternary ammonium salts, tertiary amines and the like are preferable, and tertiary amines such as triethylamine are particularly preferable.
The esterification reaction temperature is preferably room temperature (25 ° C.) to 150 ° C., more preferably 50 to 100 ° C. The reaction time is preferably about several tens of minutes to several hours.

  The amount of the dicarboxylic acid anhydride can be appropriately changed according to the content ratio of the polymer units (3) of the fluorine-containing copolymer (A).

  The acid value of the fluoropolymer (A) is preferably measured after the esterification reaction. When the acid value after the esterification reaction is more than 0 mgKOH / g and 40 mgKOH / g or less, the polymerized units to be polymerized units (3) are more than about 0 mol% and 8 mol% or less.

  The amount of the polymerization unit (2) in the fluorinated copolymer (A) can be confirmed by measuring the hydroxyl value of the fluorinated copolymer (X) before the esterification step. When the hydroxyl value is 25 to 175 mgKOH / g and the acid value after esterification is more than 0 mgKOH / g and not more than 40 mgKOH / g, the polymerization unit (2) in the fluorinated copolymer (A) Content becomes 4-30 mol%.

  When neutralizing the fluorocopolymer (A), a basic compound is added to the fluorocopolymer (A) to neutralize part or all of the carboxyl groups introduced in the esterification step. Among the carboxyl groups of the polymerization unit (3), the proportion of neutralized groups is preferably 30 to 100 mol%, more preferably 70 to 100 mol%, and 100 mol%. Further preferred.

  Neutralization is a method in which a basic compound or a basic compound and water are added to an organic solvent in which a fluorine-containing copolymer (A) having a carboxyl group obtained by esterification is dissolved at room temperature for several tens of minutes. It is preferable to carry out. According to this method, a fluorine-containing copolymer (A) in which 30 to 100 mol% of carboxyl groups are neutralized is produced.

  The addition of water in the neutralization may be simultaneous with or different from the basic compound. A part may be added simultaneously with the basic compound and the rest may be added separately. When adding simultaneously, the method of adding a basic compound as aqueous solution is preferable. When water is added separately, it may be before or after the addition of the basic compound.

The amount of water is preferably such that the solid content of the fluorine-containing copolymer (A) after neutralization is 3 to 50% by mass, and particularly preferably 15 to 40% by mass.
The basic compound that can be used for neutralization is preferably selected from compounds having a boiling point of 200 ° C. or less in order to make it difficult to remain in the coating film.

  As basic compounds, primary, secondary or tertiary such as ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, monobutylamine, dibutylamine, etc. Alkylamines; Alkanolamines such as monoethanolamine, monoisopropanolamine, dimethylaminoethanol and diethylaminoethanol; Diamines such as ethylenediamine, propylenediamine, tetramethylenediamine and hexamethylenediamine; Alkyleneimines such as ethyleneimine and propyleneimine Class; piperazine, morpholine, pyrazine, pyridine and the like.

  The amount of the basic compound is preferably such that the basic compound is 0.7 to 1.0 mol with respect to 1 mol of the carboxyl group.

  In the present invention, it is preferable to remove the organic solvent in the reaction solution containing the fluorine-containing copolymer (A) after neutralization. The removal of the organic solvent can be performed, for example, by distillation under reduced pressure.

<Compound (B)>
The composition for water-based paints of this invention contains a fluorine-containing polymer (A) and a compound (B) as an essential component. The compound part (B) is a compound having a sulfo group or a partially or wholly neutralized sulfo group and more than one isocyanate group. The present invention makes it possible to realize an aqueous coating composition having a long pot life by combining the fluorine-containing copolymer (A) and the compound (B). Moreover, the coating film formed from the composition for water-based coatings of this invention can become a coating film excellent in the external appearance.

The compound (B) is a compound having a sulfo group (—SO ₃ H) or a partially or wholly neutralized sulfo group and more than one isocyanate group. The neutralized sulfo group refers to a group obtained by reacting a sulfo group with a basic compound that can react with the group.
When the ratio of the sulfo group or neutralized sulfo group in the compound (B) is calculated as an SO ₃ group, the ratio of the sulfo group to the molecular weight of the compound (B) is 0 from the viewpoint of stability. 0.1 to 7.7 mass% is preferable, 0.2 to 6.3 mass% is more preferable, and 0.6 to 4.8 mass% is particularly preferable.

When the compound (B) has a sulfo group, the water dispersibility of the compound (B) is improved, but the water dispersibility can be further improved by neutralizing part or all of the sulfo group.
The number of isocyanate groups in the compound (B) in the present invention refers to the number of isocyanate groups in one or more compounds (B) or two or more compositions of the compound (B), and is composed of two or more compounds. Means the average number of isocyanate groups. The number of isocyanate groups in the compound (B) is more than 1, and when the compound (B) is one kind, it means that two or more isocyanate groups are present in the molecule, and the compound (B) Means that the average number of isocyanate groups of a compound having one or more isocyanate groups in the molecule exceeds one.

When the compound (B) is composed of two or more kinds, the average number of isocyanate groups is preferably 1.8 or more, more preferably 2.0 to 4.8, and particularly preferably 2.4 to 3. 8. When the compound (B) is one kind, the number of isocyanate groups in the molecule is 2 or more, preferably 2 to 5, and particularly preferably 2 to 4.
In the present invention, when the number of isocyanate groups in the compound (B) exceeds 1, the crosslinking reaction with the fluorinated copolymer (A) proceeds sufficiently.

  The average number of isocyanate groups when the compound (B) is two or more is theoretically determined by the following formula (F).

（上記式（Ｆ）中、数平均分子量はポリイソシアネート化合物の数平均分子量である。）

(In the above formula (F), the number average molecular weight is the number average molecular weight of the polyisocyanate compound.)

  The average number (y) of isocyanate groups exceeds 1, is preferably 1.8 or more, more preferably 2.0 to 4.8, and particularly preferably 2.4 to 3.8. When the isocyanate group average number (y) exceeds 1, the reaction with the fluorine-containing copolymer (A) can sufficiently proceed.

The compound (B) reacts a polyisocyanate (b1) having two or more isocyanate groups, a group capable of reacting with the isocyanate group, and a compound (b2) having a sulfo group or a neutralized sulfo group. It is preferable that it is a compound obtained by making it.
The polyisocyanate (b1) is preferably at least one selected from aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates and aromatic polyisocyanates.

  The polyisocyanate (b1) is preferably a compound prepared by modifying an isocyanate group in at least one diisocyanate selected from aliphatic diisocyanate, alicyclic diisocyanate, araliphatic diisocyanate and aromatic diisocyanate. The compound is preferably a compound having a uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure, and having two or more isocyanate groups in the molecule.

  Polyisocyanate (b1) has an isocyanate group average number (y) determined by the above formula (F) of 2.0 to 5.0, and an isocyanate group content based on the total amount of polyisocyanate (b1) is 8.0. It is preferable that it is 27.0 mass%.

As the diisocyanate preferably used for the preparation of the polyisocyanate (b1), aliphatic diisocyanate, alicyclic diisocyanate, araliphatic diisocyanate, aromatic diisocyanate and the like are preferable, and the diisocyanate having a molecular weight of 140 to 400 is particularly preferable.
Aliphatic diisocyanates include 1,4-diisocyanatobutane, 1,6-diisocyanatohexane (HDI), 2-methyl-1,5-diisocyanatopentane, 1,5-diisocyanato-2,2-dimethyl. Examples include pentane, 2,2,4- and 2,4,4-trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane and the like.

Alicyclic diisocyanates include 1,3- or 1,4-diisocyanatocyclohexane, 1,3- or 1,4-bis- (isocyanatomethyl) -cyclohexane, 1-isocyanato-3,3,5- Trimethyl-5-isocyanatomethylcyclohexane (ie, isophorone-diisocyanate), 4,4′-diisocyanatodicyclohexylmethane, 1-isocyanato-1-methyl-4 (3) isocyanato-methylcyclohexane, bis- (isocyanatomethyl) ) Norbornene and the like.
Examples of the araliphatic diisocyanate include 1,3- and 1,4-bis- (2-isocyanato-prop-2-yl) -benzene (TMXDI). Aromatic diisocyanates include 2,4- and 2,6-diisocyanatotoluene (TDI), 2,4′- and 4,4′-diisocyanatodiphenylmethane (MDI), 1,5-diisocyanatonaphthalene Etc.

When preparing polyisocyanate (b1) from diisocyanate, one kind of diisocyanate may be used or two or more kinds may be used in combination.
As the polyisocyanate (b1), a modified product obtained from an aliphatic diisocyanate and / or an alicyclic diisocyanate is preferable, and a diisocyanate trimer selected from HDI, IPDI, 4,4′-diisocyanatodicyclohexylmethane, and the like. The resulting triisocyanurate is particularly preferred.
The reaction between the polyisocyanate (b1) and the compound (b2) is carried out by reacting the isocyanate group in a ratio that exceeds 1 and remains.

The compound (b2) to be reacted with the polyisocyanate is a compound having a sulfo group or a sulfo group partially or wholly neutralized and more than one isocyanate group. Examples of the functional group having reactivity with an isocyanate group include a hydroxyl group, a primary amino group, and a secondary amino group. In the present invention, a primary amino group or a secondary amino group is preferable.
As the compound (b2), a cage compound in which one of a primary amino group or a secondary amino group and one of a sulfo group or a partially or wholly neutralized sulfo group are linked by a divalent group And a compound represented by the following formula (5) or a compound in which part or all of —SO ₃ H of the compound is neutralized is preferable.

（ただし、Ｒ^５は、水素原子、炭素数１〜２０のアルキル基、または炭素数４〜２０の１価の脂環式基を表し、Ｘは炭素数１〜６のアルキレン基、または炭素数４〜２０の２価の脂環式基を表す。）

(Wherein, ^{R 5} represents a hydrogen atom, a monovalent alicyclic group of alkyl or 4 to 20 carbon atoms, having 1 to 20 carbon atoms, X is an alkylene group having 1 to 6 carbon atoms or carbon atoms, Represents a divalent alicyclic group of 4 to 20.)

  The compound represented by the above formula (5) can be selected from compounds known as aminosulfonic acids. As the compound (b2), 2- (cyclohexylamino) ethanesulfonic acid, 3- (cyclohexylamino) propanesulfonic acid and the like are preferable from the viewpoint of reactivity with an isocyanate group. Aminosulfonic acid is a compound known as a zwitterionic substance, usually in the form of crystals, and has a melting point exceeding 300 ° C. As the compound (b2), one type may be used alone, or two or more types may be used in combination.

  When the compound (b2) is a compound having a sulfo group, part or all of the reaction may be neutralized after the reaction. The neutralization of the sulfo group may be performed before, during, or after the reaction, and the neutralization is preferably performed during the reaction between the polyisocyanate (b1) and the compound (b2).

The method for neutralizing part or all of the sulfo groups of the compound (b2) is preferably a neutralization reaction between the compound (b2) and a basic compound. As the basic compound, a tertiary amine is preferable.
Examples of the tertiary amine include tertiary monoamines such as trimethylamine, triethylamine, tripropylamine, tributylamine, dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine, N-methylpiperidine, N-ethylpiperidine; And tertiary diamines such as -bis- (dimethylamino) -propane, 1,4-bis- (dimethylamino) -butane, and N, N'-dimethylpiperazine.

As the tertiary amine, a tertiary amine used for neutralizing the sulfo group of the compound (b2) can also be used for neutralizing the sulfo group. However, since alkanolamines such as dimethylethanolamine, methyldiethanolamine, and triethanolamine have groups that react with isocyanates, it is preferable to avoid using them for neutralization reactions.
The amount of the basic compound used for neutralization is preferably 0.2 to 2.0 mol, particularly preferably 0.5 to 1.5 mol, per 1 mol of the sulfo group of the compound (b2).

  The reaction temperature for obtaining the compound (B) by reacting the polyisocyanate (b1) with the compound (b2) is preferably 40 to 150 ° C, particularly preferably 50 to 130 ° C. The reaction is preferably carried out in the presence of a catalyst. The catalyst is preferably a basic compound (preferably a tertiary amine) or a metal salt. When a basic compound and a tertiary amine are used, the same compounds as those used for neutralization of the sulfo group described later can be used. Moreover, when the same basic compound and tertiary amine used for neutralization are used, the reaction between the polyisocyanate (b1) and the compound (b2) and the neutralization reaction can be carried out simultaneously.

As the tertiary amine used as the catalyst, the same ones as described above can be used. Triethylamine, pyridine, methylpyridine, benzyldimethylamine, N, N-endoethylenepiperazine, N-methylpiperidine, pentamethyldiethylenetriamine, N, N-dimethyl-aminocyclohexane, N, N′-dimethylpiperazine and the like are preferable.
Examples of metal salts include iron (III) chloride, tri (ethyl-acetoacetate) aluminum, zinc chloride, zinc (II) n-octanoate, zinc (II) 2-ethyl-1-hexanoate, 2-ethylcaproic acid Zinc (II), zinc stearate (II), zinc naphthenate (II), zinc acetylacetonate (II), tin (II) n-octanoate, tin (II) 2-ethyl-1-hexanoate, ethyl capron Tin (II) oxide, tin (II) laurate, tin (II) palmitate, dibutyltin (IV) oxide, dibutyltin (IV) dichloride, dibutyltin (IV) diacetate, dibutyltin (IV) dimaleate, dibutyl Examples thereof include tin (IV) dilaurate, dioctyl tin (IV) diacetate, and molybdenum glycolate. One type of catalyst may be used, or a mixture of two or more types may be used.

  The amount of the catalyst is preferably 0.001 to 2% by mass, particularly preferably 0.005 to 0.5% by mass with respect to the total mass of the reaction substrate.

  Since the reaction between the polyisocyanate (b1) and the compound (b2) needs to be performed at a ratio in which the isocyanate group exceeds 1, the amount ratio of the polyisocyanate (b1) to the compound (b2) is [ Molar amount of isocyanate group of polyisocyanate (b1)]: [Mole amount of isocyanate group of compound (b2) and functional group having reactivity] = 2: 1 to 400: 1, particularly 4: 1 to 250: 1 is preferred. By increasing the amount ratio of isocyanate groups, a compound (B) having a number of isocyanate groups exceeding 1 can be obtained.

  The ratio of the isocyanate group (NCO group) to the molecular weight of the compound (B) is preferably 4.0 to 26.0% by mass, more preferably 7.0 to 23.0% by mass, and 10.0 to 22.0% by mass. % Is particularly preferred.

  The reaction between the polyisocyanate (b1) and the compound (b2) is preferably carried out in a solvent inert to the isocyanate group. The solvent is preferably selected from the solvents used in the coating composition. Ethyl acetate, butyl acetate, ethylene glycol monomethyl or ethyl ether acetate, 1-methoxyprop-2-yl acetate, 3-methoxy-n-butyl acetate , Acetone, 2-butanone, 4-methyl-2-pentanone, cyclohexanone, toluene, xylene, chlorobenzene, volatile oil, polysubstituted aromatic compounds, etc .; trade names: Solvesso (registered trademark), Isopar (registered trademark) ), Nappa (registered trademark) (all manufactured by Exxon) and shell sol (trade name, manufactured by Shell), etc .; dimethyl carbonate, diethyl carbonate, 1,2-ethylene carbonate and 1,2-propylene carbonate, Carbonates such as lactones; β-propiolactone, γ- Lactone solvents such as tyrolactone, ε-caprolactone and ε-methylcaprolactone; propylene glycol diacetate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl and butyl ether-acetate, N-methylpyrrolidone and N-methylcaprolactam . A solvent may be used individually by 1 type, or may use 2 or more types together.

  The compound (B) is preferably a compound having a polyoxyalkylene structure in the structure in order to further improve the dispersion stability in water, and is a compound having a polyoxyethylene structure and / or a polyoxypropylene structure. Preferably there is. The proportion of the polyoxyalkylene structure in the compound (B) is preferably 0 to 19.5% by mass, particularly preferably 0 to 17% by mass, and preferably 0 to 15% by mass with respect to the molecular weight of the compound (B). . The number of repeating oxyalkylene structural units in the polyoxyalkylene structure is preferably 5 to 55. As the polyoxyalkylene structure, a polyoxyethylene structure is preferable, and a polyoxyethylene structure in which the number of repeating oxyethylene structures is 5 to 55 is particularly preferable.

  As a method for introducing a polyoxyalkylene structure into the compound (B), (Method 1) a compound (b3) having a reactive group with an isocyanate group and a polyoxyethylene structure, a polyisocyanate (b1) and a compound ( a method of coexisting with the reaction of b2), (method 2) a method of reacting polyisocyanate (b1) with compound (b3) and then reacting with compound (b2), or (method 3) polyisocyanate (b1) and It is preferable to use a method in which the compound (b3) is reacted after reacting with the compound (b2).

The compound (b3) is preferably a compound having a structure in which the terminal of the polyoxyalkylene group is a hydroxyl group, preferably a polyoxyalkylene monool having one hydroxyl group or a polyoxyalkylene polyol having two or more hydroxyl groups. Xylene monool or polyoxyethylene polyol is particularly preferred.
0-25 mass% is preferable with respect to the total mass of a compound (b1), a compound (b2), and a compound (b3), and, as for the quantity of a compound (b3), 0-20 mass% is more preferable.

The compound (b3) is preferably a polyoxyalkylene monool, and a polyoxyalkylene unit having 5 to 35, preferably 7 to 30, and particularly preferably 7 to 25 polyoxyalkylene units. The polyoxyalkylene monool having is preferable.
The polyoxyalkylene monool is obtained by alkoxylating a terminal hydroxyl group of a commercially available polyoxyalkylene polyol by a known method, by adding an alkylene oxide to a compound having one or more hydroxyl groups, or an amino group. It can be obtained by subjecting a compound having one or more to an addition reaction of alkylene oxide.

  Compounds having one or more hydroxyl groups that can be used in the production of compound (b3) include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, isomer pentanol, hexanol, octanol and nonanol. N-decanol, n-dodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol, cyclohexanol, isomeric methylcyclohexanol or hydroxymethylcyclohexane, 3-ethyl-3-hydroxymethyloxetane Or monoalcohol having a saturated hydrocarbon group such as tetrahydrofurfuryl alcohol; alcohol having an unsaturated hydrocarbon group such as allyl alcohol, 1,1-dimethyl-allyl alcohol or oleyl alcohol An aromatic alcohol such as phenol, isomer cresol or methoxyphenol; an araliphatic alcohol such as benzyl alcohol, anisyl alcohol or cinnamyl alcohol;

  Examples of the compound having one or more amino groups that can be used for the production of the compound (b3) include dimethylamine, diethylamine, dipropylamine, diisopropylamine, di-n-butylamine, diisobutylamine, bis- (2-ethylhexyl) -amine. Secondary amines such as N-methyl- and N-ethylcyclohexylamine or dicyclohexylamine, and heterocyclic secondary amines such as morpholine, pyrrolidine, piperidine or 1H-pyrazole.

  The compound (b3) is a monoalcohol having an alkyl group having 1 to 4 carbon atoms, and methanol is preferable. As the alkylene oxide, ethylene oxide and / or propylene oxide are preferred.

  The oxyalkylene group in the compound (b3) may be one type or two or more types. Furthermore, the proportion of oxyethylene base in the polyoxyalkylene group is preferably 30 mol% or more, and more preferably 40 mol% or more.

  Compound (B) can be dissolved or dispersed well in water, and a composition having high sedimentation stability can be easily prepared. As the compound (B), it may be appropriately prepared by the above-mentioned method, and commercially available products such as Bihydur XP2655 (trade name, manufactured by Bayer) and Bihydur XP2547 (trade name, manufactured by Bayer) may be used.

<Aqueous medium (C)>
The aqueous coating composition of the present invention contains the fluorine-containing copolymer (A), the compound (B) and the aqueous medium (C) as essential components. As the aqueous medium (C), water or a mixture of water and a water-soluble organic solvent is preferable, and water is particularly preferable. Specific examples of the water-soluble organic solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, secondary butanol, tertiary butanol, Alcohols such as pentanol, cellosolves such as methyl cellosolve, ethyl cellosolve, isopropyl cellosolve, butyl cellosolve, secondary butyl cellosolve, propylene glycol derivatives such as propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol methyl ether acetate, ethylene Examples include glycol ethyl ether acetate, and among these, methyl ethyl ketone, acetone and the like are preferable. When the aqueous medium (C) is a mixture of water and a water-soluble organic solvent, the proportion of the water-soluble organic solvent in the mixture is more than 0 parts by weight and not more than 20 parts by weight with respect to 100 parts by weight of water. Preferably, 0.5-20 mass parts is preferable.

<Water-based paint composition>
The blending ratio of the fluorine-containing copolymer (A) and the compound (B) in the aqueous coating composition of the present invention is such that the compound (B) is added to 1 mol of the hydroxyl group of the fluorine-containing copolymer (A). It is preferable that the molar amount of the isocyanate group possessed by) is blended in an amount ratio of 0.5 to 1.5 times. The blending amount of the aqueous medium (C) is appropriately changed depending on the types of the fluorine-containing copolymer (A) and the compound (B). In general, the total mass of the fluorine-containing copolymer (A) and the compound (B) 50-300 mass parts is preferable with respect to 100 mass parts, and 80-200 mass parts is more preferable.

  Furthermore, the quantitative ratio of the fluorinated copolymer (A) and the compound (B) is such that the total amount of the fluorinated copolymer (A) and the compound (B) is 100% by mass. It is preferable to blend 5 to 50% by mass of the compound (B) with respect to 50 to 95% by mass of the (A), and particularly with respect to 65 to 90% by mass of the fluorine-containing copolymer (A). It is preferable to blend 5 to 35% by mass of (B).

  In the aqueous coating composition of the present invention, the hydroxyl group in the fluorine-containing copolymer (A) and the isocyanate group in the compound (B) react to form a urethane bond to form a cured coating film.

  In the composition for water-based paints of the present invention, a cured coating film excellent in appearance can be obtained because it is sufficiently dispersed or dissolved in the aqueous medium (C) of the fluorinated copolymer (A) and the compound (B). Furthermore, the pot life after mixing is long, and even if it is applied after several hours have elapsed from mixing, a coating film having a sufficiently excellent appearance is formed.

  The curing conditions for the aqueous coating composition of the present invention are appropriately changed depending on the type, concentration, thickness of the coating film, etc. of the fluorine-containing copolymer (A) and the compound (B). The curing time is preferably 0.1 to 48 hours. In addition, when heating is required for crosslinking and curing, a coating film can be formed by heat baking.

[Two-component curable water-based paint kit]
As a storage form of the composition for water-based paints of this invention, the form which stores each 2 agents of a main ingredient (D) and a hardening | curing agent (E) is preferable. For example, the main component (D) containing the fluorine-containing copolymer (A) and the aqueous medium (C) and the curing agent (E) containing the compound (B) are stored separately, or the fluorine-containing copolymer Main agent (D) containing coalesce (A) and aqueous medium (C1), and curing agent (E) containing compound (B) and medium not containing water (C2) (however, aqueous medium (C1) and medium) A combination of (C2) and the above aqueous medium (C)) is preferred. The main agent (D) and the curing agent (E) stored separately are mixed in use and used for forming a coating film.

  The mixing of the main agent (D) and the curing agent (E) and the application of the obtained mixture to the article to be coated can be performed by ordinary methods. Examples of the application method include roll coating, curtain flow coating, spray coating, electrostatic coating, and bell coating.

  The aqueous coating composition of the present invention may contain other optional components as long as the effects of the present invention are not impaired. The optional component is a component that can be blended in the main agent (D) and the curing agent (E) of the two-component curable water-based paint kit. Other optional components include optional components that can be included in the following two-component curable water-based paint kit.

  When the aqueous coating composition of the present invention is prepared using a two-part curable aqueous coating kit, the aqueous medium (C) includes an aqueous medium (C1) and a medium (C2) optionally containing a curing agent (E). The aqueous medium (C1) and the aqueous medium (C) are the same when the curing agent (E) does not contain the medium (C2). The total amount of the aqueous medium (C1) and the medium (C2) is the amount of the aqueous medium (C).

<Main agent (D)>
The main agent (D) is preferably one in which the fluorine-containing copolymer (A) is dispersed in the aqueous medium (C1). As the aqueous medium (C1), the same aqueous medium (C) as that described above can be used, and the preferred embodiment is also the same. The amount of the fluorinated copolymer (A) in the main agent (D) is 3 to 60 mass with respect to the total mass of the main agent (D) from the viewpoint of coating performance such as pigment dispersibility, paintability and water resistance. % Is preferable, and 15 to 50% by mass is more preferable. The content of the aqueous medium (C1) is preferably 20 to 70% by mass and more preferably 20 to 50% by mass with respect to the total mass of the main agent (D) from the viewpoints of paintability and storage stability.
Furthermore, the main agent (D) may be blended with other optional components as long as the effect of the present invention is not impaired.

  Other optional components that can be included in the main agent (D) include synthetic resins that are dispersed or dissolved in the aqueous medium (C1). Examples of the synthetic resin include fluorine-based, phenol-based, alkyd-based, melamine-based, urea-based, vinyl-based, epoxy-based, polyester-based, polyurethane-based, and acrylic-based synthetic resins. As a synthetic resin, the synthetic resin which has a functional group which reacts with compounds (B), such as a hydroxyl group and a carboxyl group, is preferable. The functional group in the synthetic resin is preferably a hydroxyl group or a carboxyl group, the hydroxyl value is preferably 20 to 150 mgKOH / g, and the acid value is preferably 10 to 100 mgKOH / g.

  The fluorine-based synthetic resin is a synthetic resin other than the fluoropolymer (A), for example, a polymer unit based on a fluoroolefin and a polymer unit based on a macromonomer having a hydrophilic portion described in Japanese Patent No. 2955336. Examples thereof include a fluorine-containing copolymer having (but not having a hydroxyl group) as an essential component. Here, the hydrophilic part means a part having a hydrophilic group other than a hydroxyl group, a part having a hydrophilic bond, and a part composed of a combination thereof. The macromonomer means a low molecular weight polymer or oligomer having a radically polymerizable unsaturated group at one end. When a fluorine-based synthetic resin is contained, the mechanical stability and chemical stability of the main agent (D) are improved, which is preferable.

As the non-fluorine-based synthetic resin, the non-fluorine-based synthetic resin may be used as it is or by seed polymerization (two-stage polymerization) of a non-fluorine monomer in the presence of the fluorine-containing copolymer (A). preferable. Moreover, you may use what seed-polymerized the non-fluorine monomer in presence of fluorine-type polymers other than a fluorine-containing copolymer (A).
When seed polymerization is carried out in the presence of the fluorinated copolymer (A), the non-fluorine monomer is preferably an acrylic ester and / or a methacrylic ester from the viewpoint of compatibility.
Seed polymerization can be carried out under the same conditions as those usually used for emulsion polymerization.

  Specifically, at least one non-fluorine monomer, a surfactant, a polymerization initiator, a chain transfer agent, a pH adjuster, and the like are mixed in the aqueous medium dispersion of the fluorine copolymer (A), and polymerization is performed. The method of performing is mentioned. When the aqueous medium dispersion of the fluorine copolymer (A) serves as a polymer emulsifier, or when the surfactant is contained in the aqueous medium dispersion of the fluorine copolymer (A), the surfactant is May not be used.

When the other synthetic resin is a fluorine-based resin, the content of the other synthetic resin in the main agent (D) is based on the total amount of the fluorine-containing copolymer (A) and the other synthetic resin. 0-90 mass% is preferable and 0-50 mass% is more preferable.
When the other synthetic resin is a non-fluorine type synthetic resin, from the viewpoint of sufficiently exerting the weather resistance of the fluorinated copolymer (A), the fluorinated copolymer (A) and other synthetic resins 0-50 mass% is preferable with respect to the total amount.

  It is preferable that the main agent (D) further contains additives such as a film-forming auxiliary, a surface conditioner, a thickener, an ultraviolet absorber, a light stabilizer, and an antifoaming agent. Moreover, you may contain a delustering agent and a coloring material according to a use.

Examples of the film-forming aid include diethylene glycol monoethyl ether acetate, 2,2,4-trimethyl-1,3-pentanediol mono (2-methylpropionate), diethylene glycol diethyl ether, and the like. Since the film-forming aid is also a kind of main organic solvent, when the film-forming aid is contained, the total amount of the organic solvent is adjusted to 10% by mass or less with respect to the total amount of the main agent (D). It is preferably 3% by mass or less. Further, the amount of the film-forming auxiliary is preferably 3% by mass or less, particularly preferably mass% or less, with respect to the total mass of the fluorine-containing copolymer (A) and other synthetic resins.
Preferred examples of the surface conditioner include polyether-modified polydimethylsiloxane and polyether-modified siloxane.
Preferred examples of the thickener include polyurethane-based associative thickeners.

  As the UV absorber, it is a UV absorber suitable for use in top coating as a transparent paint, and therefore salicylates such as methyl salicylate, phenyl salicylate, cresyl salicylate, and benzyl salicylate; 2-hydroxybenzophenone, 2-hydroxy High molecular weight modified products such as -4-benzyloxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-5-chlorobenzophenone, 2-aminobenzophenone, T-57 (trade name) manufactured by Adeka Argus Benzophenones such as 2- (2′-hydroxy-5′-t-butylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-butylphenyl) -5-chlorobenzotriazole, 2- ( 2'-hydroxy-5'-methoxyphenyl Benzotriazoles such as benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-neopentylphenyl) benzotriazole, and high molecular weight modified products such as Tinuvin 900 and 1130 (trade name) manufactured by Ciba Geigy Substituted acrylonitriles such as ethyl 2-cyano-3,3-diphenylacrylate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate, methyl α-cyano-β-methyl-4-methoxycinnamate; 2,2′-thiobis (4-octylphenolate) nickel complex, nickel complex such as {2,2′-thiobis (4-t-octylphenolate)}-n-butylamine / nickel complex; p-methoxybenzylidenemalon Dimethyl acid, resorcinol monobenzoate, hexamethylphosphoric triamide, 2,5-di UV absorbers such as enyl-p-benzoquinone; and bis (2,2,6,6-tetramethyl-4-piperidine) sebacate, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2, succinate 2,6,6-tetramethylpiperidine polycondensate, bis (1,2,2,6,6) 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate -Pentamethyl-4-piperidyl) and the like. An ultraviolet absorber may be used alone or in combination of two or more.

  0.1-15 mass% is preferable with respect to the total mass of a fluorine-containing copolymer (A) and another synthetic resin, and, as for an ultraviolet absorber, 0.1-5 mass% is more preferable.

  Examples of the light stabilizer include hindered amine light stabilizers such as MARK LA 57, 62, 63, 67, 68 (trade name) manufactured by Adeka Argus, and Tinuvin 622LD (trade name) manufactured by Ciba-Geigy. . The light stabilizer can be used as one or a mixture of two or more or in combination with an ultraviolet absorber.

Antifoaming agents include fatty acid salts, higher alcohol sulfates, liquid fatty oil sulfates, sulfates of aliphatic amines and aliphatic amides, aliphatic alcohol phosphates, sulfonates of dibasic fatty acid esters, Fatty acid amide sulfonates, alkyl allyl sulfonates, formalin condensed naphthalene sulfonates, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan Examples include alkyl esters, acrylic polymers, silcorn mixed acrylic polymers, vinyl polymers, polysiloxane compounds, and the like.
The balance (HLB value) between the hydrophilic group and the hydrophobic group showing the effect of the antifoaming agent is preferably 6 or less, particularly preferably 4 or less.

When it is necessary to adjust the gloss of the coating film, a conventional inorganic or organic delustering agent may be added.
When coloring is necessary, a coloring material such as a commercially available organic pigment, inorganic pigment, organic dye, or a pigment or dye obtained by combining these may be dispersed or mixed.
The amount of the coloring material is preferably 10 to 120% by mass, particularly preferably 20 to 100% by mass, based on the total mass of the fluorine-containing copolymer (A) and other synthetic resins.

<Curing agent (E)>
The curing agent (E) of the two-component curable aqueous paint kit contains only the compound (B) or the compound (B) and the medium (C2). As the medium (C2), a medium other than water exemplified in the aqueous medium (C), that is, the same one as the water-soluble organic solvent can be used, and a preferable embodiment is also water-soluble of the aqueous medium (C). It is the same as the organic solvent. The medium (C2) is preferably blended with the curing agent (E) immediately before mixing the curing agent (E) with the main agent (D).

  The content of the compound (B) in the curing agent (E) is 60 to 100% by mass with respect to the total amount of the curing agent (E) from the viewpoint of easy adjustment of the solid content concentration when used as a paint. Preferably, 80-100 mass% is more preferable. In addition, the content of the medium (C2) in the curing agent (E) is also 0 to 40% by mass with respect to the total amount of the curing agent (E) from the viewpoint of easy adjustment of the solid content concentration when used as a paint. Preferably, it is 0-20 mass%.

  Examples of components other than the compound (B) and the medium (C2) that can be included in the curing agent (E) include an antifoaming agent. In the medium (C2), specifically, methoxypropyl acetate, diethylene glycol diethyl ether or the like can be contained as a solvent. As for the compounding quantity of a solvent, 0-30 mass% is preferable with respect to the total mass of a hardening | curing agent (E). As the antifoaming agent, the antifoaming agents exemplified in the main agent (D) can be used, and the blending amount is preferably 0 to 2% by mass with respect to the total mass of the curing agent (E).

  The curing agent (E) may contain unreacted raw materials used for production. Examples of the unreacted raw material include diisocyanate or aminosulfonic acid. The amount of the unreacted raw material is preferably less than 1% by mass, particularly preferably less than 0.5% by mass, based on the total mass of the compound (B).

Examples of the present invention will be described below, but the present invention is not construed as being limited thereto. The hydroxyl value and acid value of the compounds used in the examples were measured by the following methods.
The acid value was determined by dissolving the polymer in tetrahydrofuran and titrating with a 0.1N potassium hydroxide-ethyl alcohol solution.
(Hydroxyl value) The polymer was dissolved in tetrahydrofuran, the hydroxyl group was acetylated using acetic anhydride, then water was added to make excess acetic anhydride acetic acid, and the acid value was measured. By quantifying the amount of acetic anhydride that was in excess, the amount of acetic anhydride consumed for the acetylation of the hydroxyl group was determined, and the hydroxyl group was calculated. If the original polymer had an acid value, it was subtracted.

[Synthesis Example 1] Preparation Example of Fluorocopolymer (A1) Fluoropolymer Lumiflon Flakes (trade name) (chlorotrifluoroethylene / ethyl vinyl ether / cyclohexyl) for paints manufactured by Asahi Glass Co., Ltd. Vinyl ether / 4-hydroxybutyl vinyl ether (molar ratio is 50/15/15/20), hydroxyl value 100 mgKOH / g, mass average molecular weight (Mw) 7,000), this was dissolved in methyl ethyl ketone (MEK), A varnish containing 60% by mass of the fluorinated copolymer (X1) as a solid content was obtained.

Add 19.3 parts of 20% by weight acetone solution of succinic anhydride and 0.072 parts of triethylamine as a catalyst to 300 parts of varnish, and react at 70 ° C. for 6 hours to esterify the fluorinated copolymer (X1). Turned into. When the infrared absorption spectrum of the reaction solution was measured, the characteristic absorption (1850 cm ⁻¹ , 1780 cm ⁻¹ ) of the acid anhydride observed before the reaction disappeared after the reaction, and the carboxylic acid (1710 cm ⁻¹ ) and ester were lost. Absorption of (1735 cm ⁻¹ ) was observed.

  The acid value of the fluorinated copolymer after esterification was 12 mgKOH / g, and the hydroxyl value was 86 mgKOH / g. From the values of the acid value and the hydroxyl value, it was found that about 2.4 mol% was esterified out of 20 mol% of 4-hydroxybutyl vinyl ether (polymerized unit (2)).

  Next, 3.9 parts of triethylamine is added to the esterified fluorine-containing copolymer (X1), and the mixture is stirred at room temperature for 20 minutes to neutralize a part of the carboxylic acid, and then 180 parts of ion-exchanged water is gradually added. Added to. As a result, a fluorine-containing copolymer (A1) in which about 2.4 mol% of all the polymerized units introduced with esterification and carboxyl groups were neutralized to form a salt was obtained.

  Acetone and methyl ethyl ketone were distilled off under reduced pressure from the aqueous dispersion of the fluorinated copolymer (A1). Further, about 90 parts of ion-exchanged water was added to obtain an aqueous dispersion in which the fluorine-containing copolymer (A1) was dispersed at a solid content concentration of 40% by mass.

[Example 1]
70 parts of TiPURER 706 (trade name, manufactured by DuPont) as the titanium oxide pigment, 7 parts of Disperbyk 190 (trade name, manufactured by BYK Chemie) as the pigment dispersant, BYK-028 (trade name, manufactured by BYK Chemie) as the antifoaming agent ), 22 parts of ion-exchanged water, and 100 parts of glass beads were dispersed using a Glen Mill disperser, and then the glass beads were filtered to prepare a pigment dispersion.

  With respect to 50 parts by mass of the aqueous dispersion of the fluorinated copolymer (A1) obtained in Synthesis Example 1, 20 parts by mass of the pigment dispersion and BYK-348 (trade name, manufactured by BYK Chemie) as a surface conditioner ), 0.1 part by mass of polyurethane associative thickener BERMODOL PUR 2150 (trade name, manufactured by Akzo Nobel) as a thickener, and Bihijoule XP2655 (trade name: manufactured by Bayer, Sulfonic acid-modified polyisocyanate (HDI trimer) (however, the sulfo group is partially neutralized with a tertiary amine, the average number of isocyanate groups: 3 to 3.5, isocyanate group content: 20.7) 5% by mass of a compound corresponding to the compound (B), which is 100% by mass in terms of solid content), and a PTFE spatula is used. 30 seconds followed by stirring and mixing Te, to obtain an aqueous coating composition 1.

  About the composition 1 for water-based paints, when the state after mixing was observed visually, the whole was mixed uniformly and the dispersion liquid was formed. After the composition for water-based paint 1 obtained was visually observed after 4 hours and 6 hours, the applicator was applied to each chromate-treated aluminum plate so that the dry film thickness was 40 μm. The gloss value of a coating film obtained by applying and drying and curing at 23 ° C. for 24 hours was measured by the following method. The results are shown in Table 1.

<Measuring method of gloss value>
Using a handy gloss meter PG-1M manufactured by Nippon Denshoku Industries Co., Ltd., 60 ° gloss was measured according to the method described in ISO2813.

[Comparative Example 1]
The type of curing agent is Bihijoule 3100 (trade name: manufactured by Bayer, polyoxyalkylene-modified polyisocyanate (HDI trimer) (average number of isocyanate groups: 3-3.5, isocyanate group content: 17.4% by mass, Except for changing the sulfonate group content: 0% by mass) to a curing agent containing 100% by mass in terms of solid content), the pigment dispersion and the aqueous solution of the fluorine-containing copolymer (A1) were the same as in Example 1. A dispersion, a curing agent, and other additive components were blended and mixed by stirring to obtain an aqueous coating composition 2.

  About the composition 2 for water-based paints, when the state after mixing was observed visually, the residue of the hardening | curing agent was seen. The obtained aqueous coating composition 2 was visually observed after 4 hours and 6 hours immediately after mixing, and after that, each of the chromate-treated aluminum plates had a dry film thickness in the same manner as in Example 1 above. The gloss value of the coating film was measured by the same method as described above when the coating film was formed to be 40 μm. The results are shown in Table 1.

  As can be seen from Table 1, in the aqueous coating composition 1 obtained in Example 1 using a compound corresponding to the above compound (B) as the polyisocyanate compound, even after 6 hours had elapsed after preparation of the composition. In addition, the film is uniformly dissolved without deterioration in fluidity and has a good appearance, and the obtained coating film has a gloss value that is not so lowered as compared to the coating film obtained immediately after the preparation, and has a good appearance.

  The aqueous paint composition and the two-component curable aqueous paint kit of the present invention have a long pot life. The coating film obtained from the aqueous coating composition of the present invention is excellent in appearance. Examples of the substrate to which the aqueous coating composition of the present invention is applied include materials such as steel, surface-treated steel, and other metals, plastics, inorganic materials, and the like, and these substrates can be used as a primer or an overcoat. Furthermore, it is also useful as a paint for imparting cosmetic properties, weather resistance, acid resistance, rust resistance, chipping resistance, electrical insulation, and the like to pre-coated metals including rust-proof steel plates, automobile coating, and plastic coating.

Claims (9)

An aqueous coating composition containing the following fluorinated copolymer (A), the following compound (B), and an aqueous medium (C).
Fluorine-containing copolymer (A): a fluorine-containing copolymer having a hydroxyl group.
Compound (B): A compound having a sulfo group or a sulfo group partially or wholly neutralized and more than one isocyanate group.   The said fluorine-containing copolymer (A) contains the polymer unit based on a fluoro olefin, and the polymer unit which has a hydroxyl group, and the hydroxyl value is 20-150 mgKOH / g, It is characterized by the above-mentioned. A composition for water-based paints.   The fluorine-containing copolymer (A) further contains a polymer unit having an acid group or a partially or completely neutralized acid group, and the acid value is more than 0 mgKOH / g and not more than 40 mgKOH / g. The composition for water-based paint according to claim 2, wherein The fluorine-containing copolymer (A) is represented by a polymer unit based on a fluoroolefin, a polymer unit represented by the following formula (2), a polymer unit represented by the following formula (3), and the following formula (4). The ratio of the polymerization unit based on the fluoroolefin to the total polymerization unit in the fluorine-containing copolymer (A) is 40 to 60 mol%, and the polymerization unit represented by the following formula (4) The composition for water-based paints according to claim 3, wherein the ratio of is 3 to 50 mol%.

(In the formula (2), R ^2b is a hydrogen atom or a methyl group, R ^2c is an alkylene group having 1 to 10 carbon atoms or a divalent alicyclic group having 4 to 10 carbon atoms. An integer of 8 and n is 0 or 1.)

(In the formula (3), R ^3b is a hydrogen atom or a methyl group, R ^3c is an alkylene group having 1 to 10 carbon atoms or a divalent alicyclic group having 4 to 10 carbon atoms, and R ^3d is a carbon number. An alkylene group having 2 to 10 carbon atoms, a divalent hydrocarbon group having 2 to 10 carbon atoms having one or more ethylenic double bonds, a divalent alicyclic group having 4 to 10 carbon atoms, or 4 to 10 carbon atoms Divalent aromatic group, R ^3e is a hydrogen atom or —NHZ ¹ Z ² Z ³ (Z ¹ , Z ² and Z ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or carbon (It is a hydroxyalkyl group of the number 1-6.) P is an integer of 0-8, q is 0 or 1.)

(In the formula (4), R ^4b is a hydrogen atom or a methyl group, R ^4e is an alkyl group having 1 to 12 carbon atoms or a monovalent alicyclic group having 4 to 10 carbon atoms. (An integer of 8 and k is 0 or 1.)   The compound (B) is a compound obtained by reacting a polyisocyanate having two or more isocyanate groups with aminosulfonic acid so that the isocyanate groups remain in a ratio exceeding 1. 5. The composition for water-based coatings of any one of Claims 1-3.   The composition for water-based paint according to claim 5, wherein the aminosulfonic acid is at least one selected from 2- (cyclohexylamino) ethanesulfonic acid and 3- (cyclohexylamino) propanesulfonic acid.   The number of isocyanate group which the said compound (B) has is 1.8 or more, The composition for water-based coating materials of any one of Claims 1-6. The number of isocyanate groups contained in the compound (B) is 2.0 to 4.8, the proportion of isocyanate groups in the molecular weight in the compound (B) is 4.0 to 26.0% by mass, and the sulfonate. The composition for water-based paints according to any one of claims 1 to 7, wherein a ratio of groups (however, calculated as SO ₃ groups) is 0.1 to 7.7% by mass.   A main agent (D) containing the fluorine-containing copolymer (A) and the aqueous medium (C), and a curing agent (E) containing the compound (B), or the fluorine-containing copolymer (A) and A main agent (D) containing an aqueous medium (C1), and a curing agent (E) containing the compound (B) and a medium (C2) containing no water (however, the aqueous medium (C1) and the medium (C2) The aqueous coating composition according to any one of claims 1 to 8 is formed by combining the main agent (D) and the curing agent (E). A two-part curable water-based paint kit characterized by forming.