JP5678808B2 - Fluorine-containing copolymer composition for water-based paint - Google Patents

Description

  The present invention relates to a fluorine-containing copolymer composition for water-based paints, and more specifically, for water-based paints capable of forming a coating film without coloring by a combination of a fluorine-containing copolymer and a predetermined block polyisocyanate. The present invention relates to a fluorine-containing copolymer composition.

  Isocyanate-based crosslinking agents are widely used mainly for urethane-based paint applications. When it is required to be one-component, such as a paint for lines, it is used as a blocked isocyanate in which an isocyanate group is blocked. However, coloring during storage of paints and coloring during baking and curing are problematic, and various blocked isocyanates have been proposed to solve this problem (for example, Patent Documents 1 and 2).

  Even when a fluorine-containing polyol is used as the main agent, the above coloration is a problem. As a method for solving this, it has been proposed that at least two of hindered phenol compounds, phosphorus-containing compounds, and semicarbazide compounds are blended in a paint (Patent Document 3). However, such an additive may adversely affect the properties of the coating film, and the trouble of compounding is troublesome. The baking temperature is set to 100 to 300 ° C, but the baking temperature is as high as 180 ° C.

JP 2008-101220 A Japanese National Patent Publication No. 11-512772 Japanese Patent Laid-Open No. 9-40905

  Then, an object of this invention is to provide the fluorine-containing copolymer composition for water-based paints which can form a coating film without coloring, without mix | blending a special additive.

［式（１）において、Ｒ^１はアルキル基、アルケニル基、アラルキル基、Ｎ−置換カルバミル基、フェニル基、ニトロ基、ハロゲン原子又は式−Ｃ（Ｏ）−Ｏ−Ｒ^２（Ｒ^２は水素またはアルキル基である。）で表される基であり、ｎは０〜３の整数であり、ｎが２以上の場合には、Ｒ^１は同一であっても異なっていてもよい。］ The present invention is a copolymer of the monomer (a), the monomer (b), and the monomer (c), the fluorine-containing copolymer (A) having a functional group that reacts with an isocyanate group, At least one of a group represented by the following formula (1) and a polyoxyethylene group represented by — (CH ₂ CH ₂ O) _p — (wherein p is an integer of 3 or more) and a polyhydroxycarboxylic acid residue block polyisocyanate having a base, a (B), and contains water, the monomer (a) is a chlorotrifluoroethylene or tetrafluoroethylene, the monomer (b) is a hydroxyl group or An unsaturated compound having a carboxy group, wherein the monomer (c) is a vinyl ether or a vinyl ester and has neither a fluorine atom nor a functional group that reacts with an isocyanate group; ), The content ratio of the monomer (b) and the monomer (c) is such that the monomer (a) is 40 to 60 with respect to all repeating units in the fluorine-containing copolymer (A). The monomer group (b) is 4 to 30 mol%, the monomer (c) is 3 to 50 mol%, and the isocyanate group in the fluorine-containing copolymer (A). , for functional group reactive with the molar ratio of the group represented by the following formula in the block polyisocyanate (B) (1) the aqueous coating fluorocopolymer heavy characterized 0.2-2 der Rukoto This is a combined composition.

[In the formula (1), R ¹ represents an alkyl group, an alkenyl group, an aralkyl group, an N-substituted carbamyl group, a phenyl group, a nitro group, a halogen atom, or a formula —C (O) —O—R ² (R ² represents hydrogen Or an alkyl group.), N is an integer of 0 to 3, and when n is 2 or more, R ¹ may be the same or different. ]

  According to the fluorine-containing copolymer composition for water-based paints of the present invention, it is possible to form a coating film with no coloration and a good color without blending special additives.

式（１）において、Ｒ^１はアルキル基、アルケニル基、アラルキル基、Ｎ−置換カルバミル基、フェニル基、ニトロ基、ハロゲン原子又は式−Ｃ（Ｏ）−Ｏ−Ｒ^２（Ｒ^２は水素またはアルキル基である。）で表される基であり、ｎは０〜３の整数であり、ｎが２以上の場合には、Ｒ^１は同一であっても異なっていてもよい。 <Block polyisocyanate (B)>
In the present invention, the blocked polyisocyanate (B) has an isocyanate group blocked with a pyrazole derivative represented by the following formula (1). As such a block polyisocyanate (B), those described in JP-A-11-512772 can be used.

In the formula (1), R ¹ represents an alkyl group, an alkenyl group, an aralkyl group, an N-substituted carbamyl group, a phenyl group, a nitro group, a halogen atom, or a formula —C (O) —O—R ² (R ² represents hydrogen or And n is an integer of 0 to 3, and when n is 2 or more, R ¹ may be the same or different.

The alkyl group is preferably a C ₁ -C ₆ alkyl group, C ₁ -C ₄ alkyl group is more preferable. As the alkenyl group, a C _{2 to} C ₆ alkenyl group is preferred. The aralkyl group, C ₁ -C ₆ alkyl group having a phenyl group is preferable. N-substituted carbamyl groups include those of the formula —C (O) NR ³ R ^{4 where} R ³ and R ⁴ are hydrogen or an alkyl or alkenyl group, where both R ³ and R ⁴ are hydrogen. Is not preferred). As halogen, chlorine or bromine is preferable. Of these, R ¹ is most preferably a methyl group. n is preferably 2 or 3, more preferably 2.

Furthermore, the block polyisocyanate (B) has a group represented by the formula (1), but is further represented by the formula — (CH ₂ CH ₂ O) p— (wherein p is an integer of 3 or more). It preferably has a polyoxyethylene group and / or a polyhydroxyalkylcarboxylic acid residue.

  The block polyisocyanate (B) having a polyoxyethylene group and / or a polyhydroxycarboxylic acid residue is, for example, a polyisocyanate compound, a polyoxyethylene compound having a group reactive with an isocyanate group and / or a polyhydroxyalkylcarboxylic acid. To form a polyisocyanate having a polyoxyethylene group and / or a polyhydroxyalkylcarboxylic acid residue, and then reacting with a pyrazole compound to obtain a blocked isocyanate. A polyisocyanate compound, a polyoxyethylene compound and / or a polyhydroxyalkyl when a polyisocyanate compound is reacted with a polyoxyethylene compound and / or a polyhydroxyalkylcarboxylic acid having a functional group that reacts with an isocyanate group. The amount ratio of the carboxylic acid is preferably 0.01 to 25 parts by mass and more preferably 0.5 to 25 parts by mass with respect to 100 parts by mass of the polyisocyanate compound to be reacted. Examples of the polyoxyethylene compound include polyoxyethylene diamine and polyoxyethylene diol. Examples of the polyhydroxyalkyl carboxylic acid include dimethylolpropionic acid.

<Fluorine-containing copolymer (A)>
The fluorine-containing copolymer (A) in the present invention is not particularly limited as long as it has a functional group that reacts with an isocyanate group. Specifically, the fluorine-containing monomer (a) (hereinafter sometimes simply referred to as “monomer (a)”) and the monomer (b) having a functional group that reacts with an isocyanate group ( Hereinafter, the copolymer may be simply referred to as “monomer (b)”.
As the monomer (a), fluorine-containing unsaturated compounds such as chlorotrifluoroethylene (CTFE), tetrafluoroethylene (TFE), hexafluoropropylene (HFP), vinylidene fluoride (VdF), vinyl fluoride ( VF) and perfluoroalkyl vinyl ether (PAVE). Among these, as a monomer (a), since the weather resistance of a coating film is excellent, CTEF and TFE are preferable.

The functional group that reacts with the isocyanate group is preferably a hydroxyl group, a carboxy group, or an amino group, and the monomer (b) includes an unsaturated compound having a hydroxyl group, a carboxy group, or an amino group. Among these, the functional group that reacts with an isocyanate group is preferably a hydroxyl group, and the monomer (b) is preferably an unsaturated compound having a hydroxyl group.
Examples of the monomer having a hydroxyl group include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methyl. Hydroxyalkyl vinyl ethers such as butyl vinyl ether, 5-hydroxypentyl vinyl ether and 6-hydroxyhexyl vinyl ether; ethylene glycol monovinyl ethers such as diethylene glycol monovinyl ether, triethylene glycol monovinyl ether and tetraethylene glycol monovinyl ether; 1-hydroxyethyl allyl ether , 3-hydroxybutyl allyl ether, 2-hydroxyethyl allyl ether, 4 -Hydroxyalkyl allyl ethers such as hydroxybutyl allyl ether and glycerol monoallyl ether; hydroxyalkyl vinyl esters such as 2-hydroxyethyl vinyl ester and 4-hydroxybutyl vinyl ester; 2-hydroxyethyl allyl ester, 4-hydroxybutyl Examples include hydroxyalkyl allyl esters such as allyl ester; (meth) acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth) acrylate, and the like.

  As the monomer having a carboxyl group, 3-butenoic acid, 4-pentenoic acid, 2-hexenoic acid, 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 or 10-undecenoic acid, acrylic acid, methacrylic acid, vinylacetic acid, crotonic acid, cinnamic acid, Unsaturated carboxylic acids such as vinyloxyvaleric acid, 3-vinyloxypropionic acid, 3- (2-vinyloxybutoxycarbonyl) propionic acid, and 3- (2-vinyloxyethoxycarbonyl) propionic acid. Allyloxyvaleric acid, 3-allyloxypropionic acid, 3- (2-allyloxybutoxycarbonyl) propionic acid, 3- Saturated carboxylic acid allyl ethers such as 2-allyloxyethoxycarbonyl) propionic acid; carboxylic acid vinyl ethers such as 3- (2-vinyloxyethoxycarbonyl) propionic acid and 3- (2-vinyloxybutoxycarbonyl) propionic acid; Saturated polycarboxylic acid monovinyl esters such as monovinyl adipate, monovinyl succinate, vinyl phthalate, and vinyl pyromellitic acid; unsaturated dicarboxylic acids such as itaconic acid, maleic acid, fumaric acid, maleic anhydride, and itaconic anhydride Examples thereof include acids or intramolecular acid anhydrides thereof; unsaturated carboxylic acid monoesters such as itaconic acid monoester, maleic acid monoester, and fumaric acid monoester.

As the monomer having an amino group, aminoalkyl vinyl ethers represented by CH ₂ ═C H —O— (CH ₂ ) _x —NH ₂ (x = 1 to 10); CH ₂ ═CH—O—CO ( _{CH 2) x -NH 2 (x} = 1~10 aminoalkyl vinyl carboxylate represented by); other aminomethylstyrene, vinylamine, acrylamide, vinylacetamide, vinylformamide or the like.

If functional group which reacts with isocyanate group is a hydroxyl group, a fluorine-containing copolymer the hydroxyl value of the (A) is, 2 0~150mgKOH / g are preferred, 40~125mgKOH / g is more preferable.

In addition to the above monomer, a monomer (c) that has neither a fluorine atom nor a functional group that reacts with an isocyanate group (hereinafter may be simply referred to as “monomer (c)”) is used. May be. Examples of the monomer (c) include vinyl ethers, vinyl esters, propenyl ethers, propenyl esters and acrylic acid esters, and methacrylic acid esters. Specifically, ethyl vinyl ether, cyclohexyl vinyl ether, Examples thereof include butyl vinyl ether, vinyl pivalate, Veova 9 and Veova 10 (trade names of vinyl esters of branched fatty acids having 9 or 10 carbon atoms, manufactured by Shell Chemical Co., Ltd.).
Among these, ethyl vinyl ether and cyclohexyl vinyl ether are preferred because they have good alternating copolymerization with the monomer (a) and can easily adjust the glass transition temperature of the copolymer.

As a content ratio of the monomer (a), the monomer (b), and the monomer (c), the monomer (a) is 40% with respect to all repeating units in the fluorine-containing copolymer. -60 mol%, monomer (b) is preferably 4-30 mol%, and monomer (c) is preferably 3-50 mol%, more preferably monomer (a) is 45-45 mol%. 55 mol%, monomer (b) is 8-25 mol%, and monomer (c) is 20-45 mol%.
A copolymer having a monomer (a) content in the above range does not have an excessively high glass transition temperature and constitutes a good film that is amorphous. Moreover, when there is too little content rate of a monomer (b), the crosslinking density after hardening will become low, and when there is too much content rate of a monomer (b), the water resistance of the coating film obtained will fall. Concerned.

  More preferable fluorine-containing copolymer (A) includes a fluorine-containing copolymer described in International Publication WO 2007/125970 (hereinafter referred to as “fluorinated copolymer (a)”). The fluorinated copolymer (a) preferably has a repeating unit represented by the formula (a1) described below and a repeating unit represented by the formula (a2). Hereinafter, the repeating unit represented by the formula (a1) is referred to as “repeating unit (a1)”.

式（ａ１）において、Ｘ^１およびＸ^２は、それぞれ独立に水素原子、塩素原子またはフッ素原子であり、Ｘ^３は塩素原子、フッ素原子または−ＣＹ^１Ｙ^２Ｙ^３（Ｙ^１、Ｙ^２、Ｙ^３はそれぞれ独立に水素原子、塩素原子またはフッ素原子である。）である。 The repeating unit (a1) is represented by the following formula (a1).

In the formula (a1), X ¹ and X ² are each independently a hydrogen atom, a chlorine atom or a fluorine atom, and X ³ is a chlorine atom, a fluorine atom or —CY ¹ Y ² Y ³ (Y ¹ , Y ² , Y ³ is each independently a hydrogen atom, a chlorine atom or a fluorine atom.

  As the repeating unit (a1), among those exemplified with respect to the monomer (a), a monomer giving the repeating unit represented by the formula (a1) or a repeating unit derived from a mixture thereof is preferable. . A preferable aspect and preferable content are also the same as those of the monomer (a).

式（ａ２）中のＲ^ｂは水素原子またはメチル基、Ｒ^２は炭素数１〜１０のアルキレン基または炭素数４〜１０の２価のシクロアルキル基であり、ｍは０〜８の整数、ｎは０または１である。 The repeating unit (a2) is represented by the following formula (a2).

R ^b in formula (a2) is a hydrogen atom or a methyl group, R ² is an alkylene group having 1 to 10 carbon atoms or a divalent cycloalkyl group having 4 to 10 carbon atoms, m is an integer of 0 to 8, n is 0 or 1.

  As the repeating unit (a2), among those exemplified as the monomer having a hydroxyl group in the monomer (b), a monomer that gives the repeating unit represented by the above formula (a2), or a mixture thereof Derived repeating units are preferred. Among these, as the monomer derived from the repeating unit (a2), hydroxyalkyl vinyl ethers are preferable and 4-hydroxybutyl vinyl ether is preferable in view of polymerizability and crosslinkability.

The content of the repeating unit (a2) in the fluorine-containing copolymer (A) is the same as the content of the monomer (b) used in the copolymerization of the fluorinated copolymer (A).

In addition to the above repeating unit, the fluorinated copolymer (A) may have a repeating unit having an acid group which may be partially or wholly neutralized. The content ratio of the repeating unit having an acid group is preferably 0.4 to 7 mol%, more preferably 1.5 to 7 mol%, based on all repeating units in the fluorine-containing copolymer (A). .

式（ａ３）中のＲ^ｂ、Ｒ^２は、式（ａ２）における各々と同じ意味であり、Ｒ^３は炭素数２〜１０のアルキレン基または炭素数４〜１０の２価のシクロアルキル基であり、Ｒ^４は水素原子または−ＮＨＺ^１Ｚ^２Ｚ^３（Ｚ^１、Ｚ^２、Ｚ^３はそれぞれ独立に水素原子、炭素原子数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。）であって、少なくともＲ^４の一部は−ＮＨＺ^１Ｚ^２Ｚ^３であり、ｐは０〜８の整数、ｑは０または１である。
含フッ素共重合体（Ａ）が有する全繰り返し単位（ａ３）のうち、Ｒ^４が−ＮＨＺ^１Ｚ^２Ｚ^３である割合は３０〜１００モル％であることが好ましく、５０〜１００モル％であることがより好ましい。 The repeating unit (a3) represented by the following formula (a3) is preferred as the repeating unit having an acid group which may be partially or wholly neutralized.

R ^b and R ² in formula (a3) have the same meanings as in formula (a2), and R ³ represents an alkylene group having 2 to 10 carbon atoms or a divalent cycloalkyl group having 4 to 10 carbon atoms. R ⁴ 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 a hydroxyalkyl group having 1 to 6 carbon atoms. Wherein at least part of R ⁴ is —NHZ ¹ Z ² Z ³ , p is an integer of 0 to 8, and q is 0 or 1.
Of all the repeating units (a3) of the fluorinated copolymer (A), the proportion of R ⁴ being —NHZ ¹ Z ² Z ³ is preferably 30 to 100 mol%, and preferably 50 to 100 mol%. More preferably.

The content ratio of the repeating unit (a3) in the fluorinated copolymer (A) is preferably 0.4 to 7 mol%, more preferably 1.5 to 7 mol%, based on the entire repeating unit of the fluorinated copolymer. %. When the ratio of the repeating unit (a3) is within the above range, the solubility or dispersibility in water is excellent, and the stability in water is excellent.
The repeating unit (a3) can be derived, for example, by reacting an acid anhydride of a divalent carboxylic acid with the repeating unit (a2) for esterification and neutralization.

式（ａ４）中のＲ^ａは水素原子またはメチル基、Ｒ^５は炭素数１〜１２のアルキル基または炭素数４〜１０の１価のシクロアルキル基であり、ｊは０〜８の整数、ｋは０または１である。好ましくは、式（ａ２）において、ｊ＝０であり、ｋ＝０または１である。 The fluorine-containing copolymer (A) may further have a repeating unit (a4) represented by the following formula (a4).

R ^a in formula (a4) is a hydrogen atom or a methyl group, R ⁵ is an alkyl group having 1 to 12 carbon atoms or ^a monovalent cycloalkyl group having 4 to 10 carbon atoms, j is an integer of 0 to 8, k is 0 or 1. Preferably, in formula (a2), j = 0 and k = 0 or 1.

  As the repeating unit (a4), among those exemplified with respect to the monomer (c), a monomer giving the repeating unit represented by the above formula (a4) or a repeating unit derived from a mixture thereof is preferable. . A preferable aspect and preferable content are also the same as those of the monomer (c).

  The content ratio of the repeating unit (a4) in the fluorinated copolymer (A) is preferably from 3 to 50 mol%, more preferably from 20 to 45 mol, based on the entire repeating unit of the fluorinated copolymer (A). %.

  The fluorine-containing copolymer (A) is a repeating unit other than the repeating unit (a1), the repeating unit (a2), the repeating unit (a3), and the repeating unit (a4) (hereinafter sometimes referred to as “other repeating unit”). .) May be included at a content ratio of 20 mol% or less based on the entire repeating unit. Other repeating units include those other than the monomers that form the repeating units (a1), (a2), (a3), and (a4) and based on monomers having an ethylenically unsaturated bond. Can be mentioned.

Particularly preferred constitutions of the fluorinated copolymer ( A ) are 45 to 55 mol% of the repeating unit (a1), 14 to 46 mol% of the repeating unit (a4), 8 to 25 mol% of the repeating unit (a2), The repeating unit (a3) is 1.4 to 6 mol% and does not contain other repeating units.

  The fluorine-containing copolymer (A) can be prepared according to a conventional method as an emulsion by emulsion polymerization, or as a dispersion by converting the solvent of the copolymer solution obtained by solution polymerization into an aqueous medium.

<Preparation of fluorine-containing copolymer composition for water-based paint>
The fluorine-containing copolymer composition for water-based paints of the present invention (hereinafter sometimes simply referred to as “water-based paint composition”) is blocked in an emulsion or dispersion containing the fluorine-containing copolymer (A). It can be prepared by mixing the polyisocyanate (B) and various additives, which will be described later if desired, by a known means such as a mixer.

The blending ratio of the fluorinated copolymer (A) and the block polyisocyanate (B) is the above formula that the block polyisocyanate (B) has relative to the functional group that reacts with the isocyanate group of the fluorinated copolymer (A). The molar ratio of the group represented by (1) is preferably 0.2 to 2, and more preferably 0.5 to 1.5.
However, when the blocked isocyanate (B) has an isocyanate group that is not blocked other than the group represented by the formula (1), a functional group that reacts with the isocyanate group of the fluorinated copolymer (A). The total molar ratio of the group represented by the formula (1) of the blocked polyisocyanate (B) to the unblocked isocyanate group is preferably the above ratio.

  As a mass ratio of the fluorine-containing copolymer (A) and the block polyisocyanate (B) in the aqueous coating composition, the above-described molar ratio conditions are secured, and the fluorine-containing copolymer (A) and The total amount of the block polyisocyanate (B) is 100% by mass, and the proportion of the fluorine-containing copolymer (A) is preferably 50 to 95% by mass, particularly preferably 65 to 90% by mass.

  The amount of water in the aqueous coating composition is preferably 20 to 80% by mass and more preferably 30 to 70% by mass in the aqueous coating composition.

  The aqueous coating composition may appropriately contain additives such as a film-forming aid, a surface conditioner, a thickener, an ultraviolet absorber, a light stabilizer, and an antifoaming agent. 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. The film forming aid is one type of organic solvent. Therefore, when a film-forming auxiliary is contained, the total content of the film-forming auxiliary and the other organic solvent is set to 10% by mass or less in the aqueous composition. The content of the film-forming auxiliary is preferably 3 parts by mass or less, more preferably 1 part by mass or less with respect to 100 parts by mass of the resin solid content.

  Preferred examples of the surface conditioner include polyether-modified polydimethylsiloxane and polyether-modified siloxane. Preferred examples of the thickener include polyurethane-based associative thickeners.

  Various known ultraviolet absorbers can be used. For example, salicylic acid esters such as methyl salicylate, phenyl salicylate, cresyl salicylate, benzyl salicylate; 2-hydroxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-5- Benzophenones such as chlorobenzophenone, 2-aminobenzophenone, and high molecular weight modified products such as T-57 manufactured by Adeka Argus; 2- (2′-hydroxy-5′-t-butylphenyl) benzo Triazole, 2- (2′-hydroxy-5′-t-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-methoxyphenyl) benzotriazole, 2- (2′-hydroxy- 3 ', 5'-di-neopentyl Benzyl) benzotriazole, benzotriazoles such as high molecular weight modified products such as TINUVIN 900, 1130 manufactured by Ciba-Geigy Corporation; ethyl 2-cyano-3,3-diphenylacrylate, 2-cyano-3 Substituted acrylonitriles such as 2-ethylhexyl, 3-diphenylacrylate, methyl α-cyano-β-methyl-4-methoxycinnamate; 2,2′-thiobis (4-octylphenolate) nickel complex salt, {2,2 Nickel complex salts such as' -thiobis (4-t-octylphenolate)}-n-butylamine / nickel complex salt; dimethyl p-methoxybenzylidenemalonate, resorcinol monobenzoate, hexamethylphosphate triamide, 2,5-diphenyl UV absorbers such as p-benzoquinone; and bis (2,2, , 6-tetramethyl-4-piperidine) sebacate, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, 2- (3,5 -Di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl) and the like, and these are one or more It can also be used in combination as a mixture. The ultraviolet absorber is preferably used in an amount of 0.1 to 15 parts by mass, particularly 0.1 to 5 parts by mass, based on 100 parts by mass of the copolymer solid content in the aqueous composition.

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

  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. Among these antifoaming agents, the antifoaming effect depends on the balance (HLB value) between the hydrophilic group and the hydrophobic group, and those having an HLB of 6 or less, particularly 4 or less are preferably employed.

  Furthermore, you may contain resin other than a fluorine-containing copolymer (A) of the quantity which does not inhibit the effect of this invention. Examples of other resins include fluorine-based, phenol-based, alkyd-based, melamine-based, urea-based, vinyl-based, epoxy-based, polyester-based, polyurethane-based, and acrylic resins. Among these, a fluorine resin and an acrylic resin are more preferable from the viewpoint of compatibility.

  Examples of the fluorine-based resin include a fluorine-containing copolymer having 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 as essential constituent components. Here, the hydrophilic part means a part having a hydrophilic group, a part having a hydrophilic bond, or a part composed of a combination thereof. The macromonomer is a low molecular weight polymer or oligomer having a radical polymerizable unsaturated group at one end. When this fluorine-containing copolymer is contained, it is preferable in that the stability of the aqueous coating composition is improved.

<Coating method>
The coating is applied by coating the aqueous coating composition of the present invention on a substrate by a known method such as air knife coating, curtain coating, roller coating, wire bar coating, or gravure coating, and heated. Can be formed. Although the heating temperature and time vary depending on the thickness of the coating film, etc., heating is performed at 80 to 150 ° C., preferably 100 to 140 ° C., for about 30 seconds to 24 hours, preferably 1 minute to 1 hour. To do.

[Example]
<Synthesis Example 1: Fluorine-containing copolymer aqueous solution 1>
Stainless steel pressure-resistant reactor with an internal volume of 2500 ml equipped with a stirrer, 590 g of xylene, 170 g of ethanol, 76 g of ethyl vinyl ether (EVE), 168 g of 4-hydroxybutyl vinyl ether (HBVE), 136 g of cyclohexyl vinyl ether (CHVE), carbonic acid 11 g of potassium and 3.5 g of perbutyl peroxypivalate (PBPV) were charged, and dissolved oxygen in the liquid was removed by degassing with nitrogen.
Next, 432 g of chlorotrifluoroethylene (CTFE) was introduced, the temperature was gradually raised, and the reaction was continued while maintaining the temperature at 65 ° C. After 10 hours, the reaction was stopped by cooling the reactor with water. After the reaction solution was cooled to room temperature, the reactor was opened to purge unreacted monomers, and then xylene and ethanol were distilled off under reduced pressure to obtain a solid fluoropolymer. The obtained fluoropolymer had a CTFE / EVE / CHVE / HBVE molar ratio of 50/15/15/20.
The obtained fluoropolymer was dissolved in methyl ethyl ketone (MEK) to obtain a varnish having a solid content of 60% by mass. To 300 g of this varnish, 4.8 g of succinic anhydride and 0.072 g of triethylamine as a catalyst were added and reacted at 70 ° C. for 6 hours for esterification. 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 carboxyl group (1710 cm ⁻¹ ) and ester Absorption of the group (1735 cm ⁻¹ ) was observed. The hydroxyl value of the fluorinated copolymer after esterification was 85 mg / KOH, and the acid value was 15 mgKOH / g.
Next, 4.9 g of triethylamine was added to the fluorinated copolymer after esterification, and the mixture was stirred at room temperature for 20 minutes to neutralize the carboxyl group in the fluorinated copolymer, and then 160 g of ion-exchanged water was gradually added. Added to.
Finally, acetone and methyl ethyl ketone were distilled off under reduced pressure. Furthermore, 20 g part of ion-exchanged water was added to obtain a fluorine-containing copolymer aqueous solution 1 having a solid content concentration of 50% by mass.

<Synthesis Example 2: Fluorine-containing copolymer aqueous solution 2>
In a stainless steel pressure resistant reactor with a stirrer having an internal volume of 2500 ml, 1280 g of water, 185 g of ethyl vinyl ether (EVE), 244 g of cyclohexyl vinyl ether (CHVE), 47 g of hydrophilic macromonomer (CM-EOVE), a hydroxyl group-containing single unit 194 g of monomer (CHMVE), 1280 g of ion-exchanged water, 2.0 g of potassium carbonate (K ₂ CO ₃ ), 1.3 g of ammonium persulfate (APS), nonionic emulsifier (Newcol-2320: manufactured by Nippon Emulsifier Co., Ltd.) And 1.4 g of anionic emulsifier (sodium lauryl sulfate) were charged, cooled with ice, and pressurized with nitrogen gas to 3.5 kg / cm ² and degassed. After repeating this pressure degassing twice and degassing to 10 mmHg to remove dissolved air, 664 g of chlorotrifluoroethylene (CTFE) was charged and reacted at 50 ° C. for 24 hours. The reaction was stopped by cooling with water. After the reaction solution was cooled to room temperature, unreacted monomers were purged to obtain a fluoropolymer copolymer aqueous solution 2. The hydroxyl value of the fluorine-containing copolymer was 55 mgKOH / g, and the solid content concentration of the fluorine-containing copolymer aqueous solution was 50%.
The structures of the hydrophilic macromonomer (CM-EOVE) and the hydroxyl group-containing monomer (CHMVE) are as follows.
_{CM-EOVE: CH 2 = CHOCH} 2 -cycloC 6 H 10 -CH 2 O (CH 2 CH 2 O) n H ( average molecular weight 830)
_{CHMVE: CH 2 = CHOCH 2 -cycloC} 6 H 10 -CH 2 OH

<Preparation of pigment composition>
210 parts of titanium oxide (Tipure R-706, manufactured by DuPont), 21 parts of pigment dispersant Disperbyk 190 (manufactured by Big Chemie, copolymer having affinity for pigment, acid value of 10 mg KOH / g), defoamer dehydrane 1620 4.5 parts (manufactured by Cognis), 64.5 parts of ion-exchanged water, and 300 parts of glass beads were mixed, dispersed using a disperser, and the glass beads were removed by filtration to prepare a pigment composition. .

<Examples 1-4 and Comparative Examples 1-4>
A fluorine-containing copolymer solution, a block polyisocyanate solution, and a pigment were mixed using a disperser with the formulation (mass%) shown in Table 1 to prepare an aqueous coating composition. In Table 1, each component is as follows.
Fluorine-containing copolymer aqueous solution 1: Synthesis example 1
Fluorine-containing copolymer aqueous solution 2: Synthesis example 2
Block polyisocyanate solution: manufactured by Baxenden, water-dispersible blocked isocyanate, TrixenDP9C / 214 (40% by mass solution (solvent is a mixture of water and Coasol. Coasol is a mixture of dicarboxylic acid and diisobutyl ether). )
Comparative block polyisocyanate solution: manufactured by Bayer, water dispersible blocked isocyanate, bihijoule TPLS2310 (38% by mass solution (solvent is a mixture of water, n-methylpyrrolidone and amine).)

<Preparation of coating film>
Each composition was applied on a chromate-treated aluminum plate to a thickness of 30 microns using an applicator and baked at each temperature shown in Table 1 for 1 hour. For comparison, a coating film dried at room temperature for 48 hours was also prepared.

The obtained coating film was evaluated by the following method.
<Whitening>
Clear coat containing no pigment (Examples 1 and 3, Comparative Examples 1 and 3) of whitening, i.e., to measure turbidity, the presence or absence of the Japanese electric food made haze meter, the haze value ○ 10 or less, 10 Ultra to 20 or less was Δ, and over 20 was x.
<Coloring>
The YI values of coating films containing white pigment (Examples 2 and 4, Comparative Examples 2 and 4) were measured with a color difference meter made by Nippon Denshoku, and each of the coating films obtained by drying at 23 ° C. for 48 hours from the same paint. The difference from the YI value, ΔYI, was determined, and those having ΔYI of 2 or less were evaluated as “◯”, and those having 2 or more as “X”.

  As can be seen from Table 1, when polyisocyanates blocked with dimethylpyrazole were used (Examples 1 to 4), a beautiful coating film without whitening and coloring could be formed at 120 ° C. In particular, the composition containing the dispersion-type fluorine-containing copolymer aqueous solution 1 of Examples 1 and 2 is practically used like the composition containing the emulsion-type fluorine-containing copolymer 2 (Example 3). Although there was no hindrance, an excellent coating film was formed without causing turbidity of the coating film. On the other hand, the composition of the comparative example was not cured unless the temperature was 160 ° C. or higher, and coloring was particularly remarkable when a pigment was included.

  The fluorine-containing copolymer composition for water-based paints of the present invention is very useful for forming a beautiful coating film at a low temperature.

Claims (8)

A monomer (a), a monomer (b), and a copolymer of the monomer (c), a fluorine-containing copolymer (A) having a functional group that reacts with an isocyanate group,
At least one of a group represented by the following formula (1) and a polyoxyethylene group represented by — (CH ₂ CH ₂ O) _p — (wherein p is an integer of 3 or more) and a polyhydroxycarboxylic acid residue And a block polyisocyanate (B) having , and water ,
The monomer (a) is chlorotrifluoroethylene or tetrafluoroethylene,
The monomer (b) is an unsaturated compound having a hydroxyl group or a carboxy group,
The monomer (c) is a vinyl ether or vinyl ester, and does not have any functional group that reacts with a fluorine atom or an isocyanate group,
The content ratio of the monomer (a), the monomer (b), and the monomer (c) is the same as the total amount of the repeating units in the fluorine-containing copolymer (A). The body (a) is 40 to 60 mol%, the monomer (b) is 4 to 30 mol%, the monomer (c) is 3 to 50 mol%,
The molar ratio of the group represented by the following formula (1) in the block polyisocyanate (B) to the functional group that reacts with the isocyanate group in the fluorine-containing copolymer (A) is 0.2 to 2. A fluorine-containing copolymer composition for water-based paints.

[In the formula (1), R ¹ represents an alkyl group, an alkenyl group, an aralkyl group, an N-substituted carbamyl group, a phenyl group, a nitro group, a halogen atom, or a formula —C (O) —O—R ² (R ² represents hydrogen Or an alkyl group.), N is an integer of 0 to 3, and when n is 2 or more, R ¹ may be the same or different. ]   The fluorine-containing copolymer composition for water-based paint according to claim 1, wherein the monomer (c) is at least one of ethyl vinyl ether and cyclohexyl vinyl ether. The fluorine-containing copolymer for water-based paint according to claim 1 or 2 , wherein at least a part of the functional group is a hydroxyl group, and the fluorine-containing copolymer (A) has a hydroxyl value of 20 to 150 mgKOH / g. Combined composition. The fluorine-containing copolymer (A) further has a repeating unit having an acid group, which may be partially or wholly neutralized, and the content ratio of the repeating unit having an acid group is The fluorine-containing copolymer composition for water-based paints as described in any one of Claims 1-3 which is 1.5-7 mol% with respect to all the repeating units in a fluorine copolymer (A). The fluorine-containing copolymer composition for water-based paints as described in any one of Claims 1-4 whose said block polyisocyanate (B) is water-dispersible. The content of the fluorine-containing copolymer (A) is 50 to 95% by weight relative to the total weight of the fluorine-containing copolymer (A) and the blocked polyisocyanate (B), according to claim 1 to 5 The fluorine-containing copolymer composition for water-based paints as described in any one. The fluorine-containing copolymer composition for water-based paints as described in any one of Claims 1-6 containing resin other than a fluorine-containing copolymer (A). The content of the fluorine-containing copolymer (A) other than resin, fluorine-containing copolymer (A) for an aqueous coating material fluorocopolymer according to claim 7, which is 10 to 50 parts by weight per 100 parts by weight of Polymer composition.