JP2000044634A - Fluorine-based copolymer and composition for fluororesin coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluorine-based copolymer capable of manifesting a high solubility in solvents and readily forming a coating film excellent in impact and fouling resistances, etc., and useful as a solvent-soluble type coating material by including a fluoroolefin unit and limiting the molecular weight and the distribution of the molecular weight within specific ranges. SOLUTION: This fluorine-based copolymer is obtained by polymerizing (A) a fluoroolefin with (B) a monomer having a cross-linking site (e.g. the monomer having OH, carboxy, an organosilicon group having a hydrolyzable group, a β-keto ester group or epoxy group) and (C) other monomers (e.g. the monomer having >=2 polymerizable unsaturated bonds in the molecule). The copolymer is regulated so as to respecitively provide 1,000-40,000 number-average molecular weight (Mn), 100,000-500,000 weight-average molecular weight (Mw) and >=4 ratio of the molecular weights Mw/Mn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorine-based copolymer suitable for a solvent-soluble paint and a composition for a fluororesin paint using the same.

[0002]

2. Description of the Related Art Conventionally, fluororesin coatings utilizing the excellent weather resistance of a fluorocopolymer have been industrialized. Particularly recently, a solvent-soluble fluorine-based copolymer having a cured site has been synthesized (for example, JP-A-57-34107, JP-A-61-57609, etc.), and is used for construction, automobile, and chemical. It is widely used as a weather-resistant paint in fields such as industry. These paint resins are mainly made of fluorine-based monomers such as chlorotrifluoroethylene, tetrafluoroethylene or vinylidene fluoride, and are made by using hydrocarbon-based monomers such as vinyl esters and vinyl ethers as copolymerization components. Is increased in solubility.

However, the molecular weight of these fluororesins for coatings is in the range of about 3,000 to 20,000 in terms of number average molecular weight and about 10,000 to 60,000 in terms of weight average molecular weight because of the necessity of increasing the solvent solubility. Used within. In the form of radical polymerization by solution polymerization, which is widely used as a production method, the reaction conditions are such that the polymerization reaction proceeds mildly and the effects of chain transfer reaction, disproportionation reaction and termination reaction of growing radicals are reduced. Can increase the molecular weight, but both the number-average molecular weight and the weight-average molecular weight increase. For example, a copolymer having a weight-average molecular weight of 100,000 or more not only reduces the polymerization yield but also reduces the number-average molecular weight. A phenomenon was observed in which the solvent solubility was extremely reduced due to the increase in molecular weight.

[0004] For this reason, for example, as a resin for a fluorine coating for coil coating requiring impact resistance and bending workability, it is difficult to satisfy required performance of a coating film while maintaining solubility. Or a resin having a high flexibility, or a resin having a low glass transition point, which has been used as a paint for factory line coating. However, on the other hand, these restrictions on the molecular weight have also been the main causes of the drawbacks that lower the hardness, adhesion and stain resistance of the coating film. Further, fluororesin paints have come to be widely used, and even higher levels of weather resistance, which is the most important performance thereof, are required. By increasing the weather resistance, it is possible to greatly extend the number of years of coating, and it is possible to reduce the total cost and the total amount of solvent.

[0005]

DISCLOSURE OF THE INVENTION The present invention is to increase the molecular weight of the fluorine-based copolymer (the molecular weight referred to in the present specification is a value in terms of polystyrene measured by gel permeation chromatography (GPC)). Fluororesin that has high solvent solubility while improving the impact resistance, stain resistance, bending workability, weather resistance, etc. of the coating film, and has excellent coating film forming ability by using its fluorine-based copolymer A coating composition is prepared.

[0006]

Means for Solving the Problems The present inventors have studied the molecular weight distribution and solvent solubility of a fluororesin,
A fluorine-based copolymer with a sufficiently wide molecular weight distribution has a uniform film despite containing high-molecular-weight copolymers that are favorable for coating properties such as impact resistance, stain resistance, bending workability, and weather resistance. Have been found to exhibit the excellent solvent solubility necessary for efficiently forming the compound, and have reached the present invention.

That is, the present invention has a number average molecular weight of 1,000 to 40,000 and a weight average molecular weight of 100,000 obtained by polymerizing a monomer having a crosslinking site with a fluoroolefin and another monomer. It is a fluorine-based copolymer having a weight-average molecular weight / number-average molecular weight ratio of 4 to 500,000 or more, and a composition for a fluororesin coating comprising the necessary amount of a solvent and a solvent.

Hereinafter, the present invention will be described in detail. The fluorine-based copolymer of the present invention may be a random copolymer or a graft polymer, but in the present specification, these may be collectively referred to as a fluorine-based copolymer. The fluoroolefin used for the fluorine-based copolymer of the present invention,
A compound in which at least one hydrogen atom of ethylene has at least one fluorine atom substituted with a halogen atom (fluorine, chlorine, bromine), a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, etc., for example, chlorotrifluoroethylene , Tetrafluoroethylene, vinylidene fluoride, vinyl fluoride, hexafluoropropene, hexafluoroisobutene and the like. Although the copolymerization ratio of these monomers is not necessarily limited, it is preferably not less than 15 mol% of all the monomers since the decrease in weather resistance is not preferable. In order to maintain solvent solubility and flexibility, the copolymerization ratio is preferably 70% or more. It is preferably at most mol%.

The monomer having two or more polymerizable unsaturated bonds in the molecule used in the present invention contains at least two unsaturated bonds copolymerizable with a fluoroolefin in the monomer. If so, the structure is not particularly limited. Substantially all of the two or more polymerizable unsaturated bonds in the molecule participate in the polymerization reaction to form a bond, but some of the unsaturated bonds may remain in the fluorine-based copolymer. Since the vinyl group copolymerized with the fluoroolefin is preferably contained as a structure of vinyl carboxylate, vinyl ether, allyl ether, etc., divinyl esters of dicarboxylic acid having two or more vinyl groups of these structures, divinyl ether Or diallyl ethers are particularly preferably used. When the amount is small, a dihydric or tri (meth) acrylate of a polyhydric alcohol can be used. In the present invention, while maintaining the number average molecular weight of the fluorocopolymer low by adding these monomers, the reason why the weight average molecular weight can be increased is not clear, but it is formed during the polymerization process. It is presumed to be based on a loosely crosslinked structure. Therefore, it is not desirable to increase the amount of the monomer having two or more polymerizable unsaturated bonds in the molecule too much.
About 5 mol%, preferably about 0.01 to 3 mol%. If it is less than 0.001 mol%, the effect of increasing the weight average molecular weight is low, which is not preferable. On the other hand, if it exceeds 5 mol%, not only gelation occurs during polymerization, but also the weight average molecular weight is increased, but the number average molecular weight is also increased, so that the molecular weight distribution is not broadened, and the solvent solubility is also decreased. Absent.

The divinyl ester or diallyl ester used in the present invention is a saturated or unsaturated aliphatic, alicyclic or aromatic dicarboxylic acid having 3 to 15, preferably 3 to 10 carbon atoms. Divinyl or diallyl esters of acids. To be more specific, examples thereof include unsaturated hydrocarbon dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, which are dicarboxylic acids of saturated hydrocarbons. Examples thereof include divinyl or diallyl esters such as phthalic acid, isophthalic acid, and terephthalic acid, which are dicarboxylic acids of aromatic hydrocarbons such as maleic acid and fumaric acid.

The divinyl ethers are represented by the general formula: CH ₂ ＣＨCH— (CH ₂ ) _n —O— (CH ₂ ) _n —CHＣＨCH ₂ (1) (where n represents 0 or an integer of 1 or more) ), And examples thereof include divinyl ether and diallyl ether. Also, ethers obtained from polyhydric alcohols and allyl alcohols, for example, trimethylolpropane triallyl ether or the like, or pentaerythritol tetraallyl ether or trimethylolpropane diallyl ether and polybasic acid or polyisocyanate described in the same manner And oligomers obtained from the above.

The (meth) acrylates include (meth) acrylates.
Examples include allyl acrylate and vinyl (meth) acrylate. Further, oligomers such as trimethylolpropane triacrylate, pentaerythrit tetraacrylate, and dipentaerythrit hexaacrylate, which are (meth) acrylates of polyhydric alcohols, may be mentioned. Further, epoxy acrylates, urethane acrylates, polyester acrylates and the like having two or more polymerizable unsaturated bonds are exemplified.

The method for introducing a crosslinked site in the present invention is not particularly limited. For example, a method for introducing by crosslinking a monomer having a functional group can be used. That is, a functional group that can be a cross-linking site selected from a double bond as a polymerizable site and a hydroxy group, a carboxyl group, an organosilicon group having a hydrolyzable group, a β-ketoester group or an epoxy group as a reactive cross-linking site Can be copolymerized. Specifically, allyl ethers, vinyl ethers, crotonic acid-modified compounds, (meth) acrylates having these cross-linking sites in the molecule,
Examples include unsaturated carboxylic acids, vinyl esters, and monoesters of unsaturated dicarboxylic acids.

The monomer having a hydroxy group is represented by the general formula

[0015]

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(Wherein R ³ is the same or different and represents hydrogen or an alkyl group having 1 to 3 carbon atoms; l, p, q,
s and t are 0 or 1, r, m, and n represent an integer of 0-12. A) alkylene glycol monoallyl ethers such as ethylene glycol monoallyl ether, propylene glycol monoallyl ether, diethylene glycol monoallyl ether, polyethylene glycol monoallyl ether, hydroxybutyl allyl ether, or allyl alcohol; General formula,

[0017]

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(Wherein R ³ is the same or different and represents hydrogen or an alkyl group having 1 to 3 carbon atoms; l, p, q,
s and t are 0 or 1, r, m, and n represent an integer of 0-12. And the like, for example, hydroxymethyl vinyl ether, 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 1,4-cyclohexanediene Table methanol vinyl ether, and the like diethylene glycol ether of the general formula, in _{CH (-CH 3) = CHCOO- (} CH 2) p -OH (4) ( wherein, p is an integer of 2 to 10.) Compounds, for example, crotonic acid-modified compounds such as hydroxyethyl crotonate and hydroxybutyl crotonate;

[0019]

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(Wherein R ⁵ is hydrogen or a methyl group, R ³ is the same or different and represents hydrogen or an alkyl group having 1 to 3 carbon atoms, and l, p, q, s, and t are 0 or 1, r, m, n
Represents an integer of 0 to 12. ), For example, hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, polycaprolactone (meth) acrylate, and the like.

The carboxyl group-containing polymerizable compound used in the present invention is not particularly limited, but may be an unsaturated carboxylic acid or unsaturated dicarboxylic acid monoester,
For example, acrylic acid, methacrylic acid, crotonic acid, vinyl acetic acid, undecylenic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, monoalkyl maleate, monoalkyl itaconate, monoallyl succinate, adipic acid Monoallyl, monoallyl sebacate, monoallyl cyclohexanedicarboxylate, monovinyl succinate, monovinyl adipate, monovinyl sebacate, monovinyl cyclohexanedicarboxylate and the like.

Examples of the organic silicon group-containing polymerizable compound having a hydrolyzable group, the general _{formula, CH 2 = CH-Si (} R 4) 3 (6) ( wherein, R ⁴ is 1 to 22 carbon atoms Which may have a branched alkyl group, an alkoxy group, a cycloalkyl group which may have a substituent or a monovalent aromatic group, at least one of which is an alkoxy group.) Examples include a vinyl compound having a group, or a compound having another polymerizable group and another hydrolyzable group. Such a compound is preferably a terminal olefinically unsaturated bond from the viewpoint of copolymerization. Specific examples of the hydrolyzable group include methoxy, ethoxy, propoxy, isopropoxy, butoxy and methoxyethoxy. Such as an alkoxy group or an alkoxyalkoxy group,
Acyloxy group such as formyloxy, acetoxy, propionoxy, halogen (fluorine, chlorine, bromine or iodine)
And the like. Such organosilicon compounds include:
For example, methacryloxymethyltrimethoxysilane, 3-
Acryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinylmethyldiethoxysilane, vinyltrimethoxysilane, vinylmethyltris (2 -Methoxyethoxy) silane, vinyltriacetoxysilane, vinyltrimethylsilane, vinylmethyldichlorosilane, vinyltrichlorosilane and the like. Furthermore, it has an alkoxysilyl group (meth)
Acrylic ester compounds can also be used.

The polymerizable compound having an epoxy group used in the present invention includes allyl glycidyl ether, vinyl glycidyl ether, 3,4-epoxycyclohexylmethyl vinyl ether, 3,4-epoxycyclohexyl (meta- ) Acrylate and the like.

In addition, the general formula CH ₂ ＣＨCH— (CH ₂ ) _q —OCH ₂ CH ₂ OC (＝ O) — (CH ₂ ) ₅ —OH (7) (where q represents 0 or 1) ) Caprolactone-modified vinyl ether or allyl ether represented by
Specifically, ε-caprolactone-modified vinyl ether or allyl ether, Daicel Chemical's Praxel (trade name), or the like can be used. Also, allyl acetoacetate having a β-ketoester group can be used.

Further, the fluorine-based copolymer of the present invention further comprises a monomer having no crosslinking site as described above, for example, fatty acid vinyl esters, alkyl vinyl ethers, alkyl allyl ethers, (meth) acrylic acid esters The solubility, flexibility, fluidity, and the like can be further improved by copolymerization of a class or other general-purpose monomer. The composition ratio of these monomers is 10 to 10
It is in the range of 70 mol%, preferably in the range of 10 to 60 mol%. If the amount is less than 10 mol%, the solubility and flexibility of the obtained copolymer may not be sufficient, and if it exceeds 70 mol%, the weather resistance of the coating film is undesirably reduced.

The fatty acid vinyl ester which can be used in the present invention has a general formula CH ₂ ＣＨCH—OC (＝ O) —R ¹ (8) (wherein R ¹ may have a branch having 1 to 22 carbon atoms). alkyl or ^{_{- (CH 2) m -R 2}} - (CH 2) n -
H (R ² represents a cycloalkylene group which may have a substituent or a divalent aromatic group, and m and n each represent an integer of 0 to 12). ), Such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl isocaproate, vinyl pivalate, vinyl caprylate, vinyl caproylate, and vinyl stearate. , Versatic 9
Vinyl acetate (Veova 9 (manufactured by Shell Chemical Co., Ltd.)), Versatic 10 vinyl acetate (Veoba 10 (manufactured by Shell Chemical Co., Ltd.)), vinyl cyclohexanoate, vinyl benzoate, vinyl p-toluate, p-tert- And vinyl butyl benzoate. Alkyl vinyl ethers are represented by the general formula: CH ₂ ＣＨCH—O—R ¹ (9) (wherein, R ¹ is an alkyl group having 1 to 22 carbon atoms or an alkyl group or — (CH ₂ ) _m —R _² - (CH ²⁾ _n -
H (R ² represents a cycloalkylene group which may have a substituent or a divalent aromatic group, and m and n each represent an integer of 0 to 12). ), For example, ethyl vinyl ether, propyl vinyl ether, isopropyl vinyl ether, butyl vinyl ether, te
rt-butyl vinyl ether, pentyl vinyl ether,
Chain alkyl vinyl ethers such as hexyl vinyl ether, isohexyl vinyl ether, octyl vinyl ether, and 4-methyl-1-pentyl vinyl ether. Examples thereof include cycloalkyl vinyl ethers such as cyclopentyl vinyl ether and cyclohexyl vinyl ether, and aryl vinyl ethers such as phenyl vinyl ether and toluyl vinyl ether.

Alkyl allyl ethers or aryl allyl ethers are represented by the general formula: CH ₂ ＣＨCHCH ₂ —O—R ¹ (10) (where R ¹ is an alkyl having 1 to 22 carbon atoms which may have a branch) Group or — (CH ₂ ) _m —R ² — (CH ₂ ) _n —
H (R ² represents a cycloalkylene group which may have a substituent or a divalent aromatic group, and m and n each represent an integer of 0 to 12). ), For example, ethyl allyl ether, butyl allyl ether, cyclohexyl allyl ether and the like.

The (meth) acrylates are represented by the general formula: CH ₂ ＣC (—R ⁵ ) —COO—R ¹ (11) (in the formula, R ¹ may have a branch having 1 to 22 carbon atoms. there alkyl or ^{_{- (CH 2) m -R 2}} - (CH 2) n -
H (R ² represents a cycloalkylene group which may have a substituent or a divalent aromatic group, and m and n each represent an integer of 0 to 12). ), And R ⁵ represents hydrogen or a methyl group. ), For example, methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, (meth) acrylic acid-n
-Butyl, isobutyl (meth) acrylate, -tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, (meth) Examples include isooctyl acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, and benzyl (meth) acrylate.

Examples of general-purpose monomers include aromatic vinyl such as styrene, ethylene, propylene and butene.
1, α-olefins such as isobutene can be used. The fluorine-based copolymer of the present invention is produced by adding a polymerization initiator to a predetermined ratio of a monomer composition in the presence of a polymerization medium and performing a copolymerization reaction. As the polymerization form, solution polymerization, suspension polymerization, and emulsion polymerization are possible. The polymerization initiator can be appropriately selected according to the type of polymerization, polymerization temperature, medium and the like. Specifically, for example, dicarbonates such as diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, n-heptafluorobutylic peroxide, lauroylperoxypiperoxide Baleto,
Diacyl peroxides such as t-butyloxy neodecanoate; alkyl peroxides such as di-t-butyl peroxide and t-butyl cumyl peroxide; t-butyl peroxy pivalate; t-butyl peroxy neodecaate Conventional radical initiators such as peroxyesters such as noate can be used. Further, water-soluble peroxides, persulfates, water-soluble azo compounds and the like can also be used. The temperature of the polymerization step depends on the radical polymerization initiator used,
Usually, it is 0 to 130 ° C.

The polymerization medium in the present invention is not particularly limited as long as it does not significantly inhibit polymerization. Examples of the medium include water, alcohols such as t-butanol, n-butanol, isopropanol, ethanol, methanol, ethyl cellosolve and butyl cellosolve; n-hexane, n
-Saturated hydrocarbons such as heptane, aromatic hydrocarbons such as toluene and xylene, fluorines such as trichlorotrifluoroethane, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and esters such as ethyl acetate and butyl acetate. And petroleum naphthas such as mineral terpenes and isopentane can be used alone or in combination.

In the present invention, a graft polymer having a branched structure with respect to a resin skeleton containing a structure based on fluoroolefin is also preferably employed. The graft polymerization method is
Although not particularly limited, a reactive group such as a hydroxy group or a carboxyl group in a fluorine-based copolymer containing a structure based on a fluoroolefin produced by the above method has a polymerizable double bond having an isocyanate group or an epoxy group. A method of polymerizing a monomer again in the presence of a compound, for example, an unsaturated bond-containing fluororesin obtained by reacting isocyanate alkyl (meth) acrylate or glycidyl (meth) acrylate, A method in which a monomer is polymerized again starting from a peroxy group of a resin containing a base structure. As the monomer that can be used for these graft polymerizations, any polymerizable compound that has already been presented in the present specification can be used without limitation, and glycidyl propyl (meth) acrylate, scissocyanate propyl (meth) acrylate, fluoroalkyl ( (Meth) acrylates and (meth) acrylates represented by formula (5) or (11) are preferred. Further, those exemplified therein are more preferable. These graft monomers can be appropriately used in combination. As the amount of these graft monomers, the amount of the fluorocopolymer 10
0 to 100 parts by weight, 1 to 200 parts by weight, 10 to 15 parts by weight
0 parts by weight is preferred. When the amount is less than 1 part by weight, there is no effect of graft polymerization, and when the amount is more than 200 parts by weight, a paint having poor weather resistance may be obtained, which is not preferable.

Examples of the monomer having a peroxy group used for introducing a peroxy group as a starting point of the graft polymerization include various unsaturated peroxy esters or peroxy carbonates.
-Butyl peroxy methacrylate, di (t-butyl peroxy) fumarate, t-butyl peroxycrotonate, t-butyl peroxy allyl carbonate, t-
Hexyl peroxyallyl carbonate, 1,1,3
3-tetramethylbutyl peroxyallyl carbonate, t-butyl peroxymethallyl carbonate, 1,
Examples thereof include 1,3,3-tetramethylbutyl peroxymethallyl carbonate, p-menthane peroxyallyl carbonate, p-menthane peroxymethallyl carbonate and the like. The copolymerization ratio of these peroxy group-containing monomers is not particularly limited.
It is preferable to use it in the range of mol%. If the amount is less than 0.01 mol%, the amount of the graft starting point is insufficient, and the ratio of the graft resin is undesirably reduced. On the other hand, if it exceeds 15 mol%, the amount of the graft starting point is too large and the molecular weight does not become large, which is not preferable. Further, the peroxy group tends to remain, which may adversely affect the weather resistance.

The fluorine-based copolymer of the present invention may be a fluorine-based copolymer modified by treating the fluorine-based copolymer produced by the above polymerization method with a bifunctional compound.
The fluorine-based copolymer or the fluorine-based graft copolymer is reacted with a compound having a functional group and an alkoxysilyl group having reactivity to a cross-linking site contained in these copolymers, thereby obtaining a fluorine-based copolymer. A hydrolyzable organic silicon group can be introduced into the union. For example, when the fluorine-based copolymer has a hydroxy group or a carboxyl group, an alkoxysilyl compound having an isocyanate group, for example, isocyanate propyl trimethoxy silane, isocyanate propyl triethoxy silane,
Alkoxysilyl compounds having an epoxy group, for example,
Glycidyltrimethoxysilane, glycidyltriethoxysilane and the like, an alkoxysilyl compound having an amino group, for example, aminopropyltrimethoxysilane and aminopropyltriethoxysilane, etc. it can.

The molecular weight of the fluorinated copolymer according to the present invention is an essential part in the present invention. By setting the molecular weight to a specific molecular weight, sufficient film-forming ability, that is, strong adhesion at a sufficient film thickness is exhibited. This is a fluorine-based copolymer for a paint, which has a capability of forming a coating film having excellent smoothness and gloss, and has a coating film excellent in impact resistance and bending workability.

The molecular weight of the fluorocopolymer according to the present invention is such that the number average molecular weight is 1,000 to 40,000,
The weight average molecular weight is from 100,000 to 500,000. That is, 4 without increasing the number average molecular weight so much.
The weight average molecular weight, which is obtained by averaging the total number of squares of the molecular weight by the total weight, is set to 100,000 or more. As a result, the molecular weight distribution is widened while the number average molecular weight is increased, so that the solvent is dissolved in the solvent. Thus, it is possible to obtain a fluorine-based copolymer which can maintain good properties, is excellent in impact resistance, adhesion, bending workability, and further has improved weather resistance. If the number average molecular weight is less than 1,000, a coating film with sufficient strength cannot be obtained, and if the number average molecular weight exceeds 40,000, the solubility in a solvent decreases, and it is difficult to form a smooth coating film. Is not preferred. On the other hand, if the weight average molecular weight is less than 100,000, sufficient impact resistance, adhesion, and bending workability of the coating film cannot be obtained. It is not preferable because it becomes difficult to form a film. On the other hand, when the ratio of weight average molecular weight / number average molecular weight is less than 4.0, the solubility of the fluorine-based copolymer in a solvent is reduced, and the ability to form a coating film is extremely poor.

The composition for a fluororesin coating is obtained from the fluorocopolymer of the present invention and a solvent in an amount necessary for dissolving the copolymer. The solvent is not particularly limited as long as it is used in the field of paint, but hydrocarbons, alcohols,
Examples thereof include organic compounds belonging to ethers, chlorinated hydrocarbons, esters, glycols, fluorinated chlorinated hydrocarbons, fluorinated hydrocarbons, and perfluoro compounds. Examples of such solvents include heptane, isooctane, cyclohexane, toluene, xylene, decalin, ethylbenzene, methanol, ethanol, isopropanol, n-butyl alcohol, isobutyl alcohol, secondary butyl alcohol, tertiary butyl alcohol,
Isoamyl alcohol, 2-ethylhexanol, cyclohexanol, n-butyl ether, dioxane, acetone, methyl ethyl ketone, isobutyl ketone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, isophorone, methylene chloride, chloroform,
1,2-dichloroethane, trichloroethylene, tetrachloroethylene, dichloropropane, methyl formate, ethyl formate, butyl formate, amyl formate, methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, amyl acetate, isoamyl acetate, acetic acid 2 -Ethyl cyclohexyl, ethyl propionate, butyl propionate, butyl butyrate, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,
Ethylene glycol monoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol dimethyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, triethylene glycol, glycerin, 1-dodecyl-2-pyrrolidone, Non-limiting examples include 2-pyrrolidone, perfluorohexane, perfluoropentane, perfluorooctane, perfluoroheptane and the like. Further, a mixed solvent which is commercially available for diluting paint under the name of a thinner, a paint thinner or the like may be used. In addition, aromatic petroleum naphtha and mineral spirits (mineral terpenes), which are mixtures of aromatic hydrocarbons, cleaning solvents, light solvent naphthas,
Heavy solvent naphtha, creosote oil, turpentine oil, aliphatic hydrocarbons, naphthenic hydrocarbons and the like can also be used.

The fluorocopolymer prepared as described above can be formed into a coating in the same manner as ordinary coatings, and pigments and dyes can be added as appropriate. Light stabilizers, rust preventives, dispersants, anti-dripping agents, thickeners, film-forming auxiliaries, fungicides, antifreezing agents and the like can also be added.

Further, other resins, for example, a fluororesin, a fluoropolyol, another fluororesin having an alkoxysilyl group, an acrylic resin, an acrylic polyol, a polyvinyl ester, a silicone compound, a polyalkylene glycol, and an alkyd resin are appropriately added. It is possible.

The form of the paint using the fluorine-based copolymer of the present invention is not particularly limited, and examples thereof include a solvent-type room temperature crosslinking system, a solvent-type baking crosslinking system, an aqueous emulsion-type room temperature crosslinking system, an aqueous emulsion-type baking crosslinking system, Solvent-free room temperature crosslinking systems, solvent-free baking crosslinking systems, and non-crosslinking systems can be used, and they can be used as enamels or clear coatings.

The cross-linking structure of the paint using the fluorocopolymer of the present invention is not particularly limited, and a curing agent having a functional group capable of forming a bond by reacting with a functional group at a cross-linking site may be used. The curing agent may be a monomer type, a prepolymer type or a resin. For example, when the cross-linking site is a hydroxy group, a carboxyl group, or an epoxy group, a melamine curing agent, a urea resin curing agent, a polybasic acid curing agent, an isocyanate curing agent, an epoxy curing agent, or the like is used as a crosslinking agent (curing agent). An appropriate amount can be used depending on the amount of the functional group of the polymer. When an alkoxysilyl group is used as a crosslinking site or a functional group of a curing agent, the reaction can be promoted by adding an organotin compound. At this time, it is also preferable to add silicate as a curing agent.

More specifically, isocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate and diphenylmethane diisocyanate, and isocyanurates, blocked isocyanates and buret forms thereof, or melamines such as alkylated melamine, methylol melamine and imino melamine. Resins, amino compounds such as urea resins, and epoxy curing agents having two or more epoxy groups obtained by the reaction of a polyphenol such as bisphenol A with epichlorohydrin can be appropriately selected and used. Further, a fluorine resin or a non-fluorine resin having a functional group such as a carboxyl group, an amino group, an epoxy group, and an isocyanate group can also be used as a curing agent. Hereinafter, the present invention will be described specifically with reference to examples, but embodiments of the present invention are not limited thereto. In the examples, “parts” means “parts by weight” unless otherwise noted.

[0042]

EXAMPLES [Examples 1 to 5] 102 g of vinyl acetate (19.8 mol% of all monomers, the same applies hereinafter) was placed in a 2.0-liter SUS autoclave equipped with a magnetic stirrer.
211 g (19.1 mol%) of versatic vinyl 9 acidate,
61 g (10 mol%) of ethylene glycol monoallyl ether, 11 g (1 mol%) of undecylenic acid, 1.2 g (0.1 mol%) of divinyl adipate, 2 g of t-butyl peroxypivalate, 5 g of celite, 73 g of butyl acetate
After charging 6 g and repeating degassing and replacement with nitrogen gas three times, 349 g (50 mol%) of chlorotrifluoroethylene was charged and polymerization was carried out at 55 ° C. for 18 hours. After the completion of the polymerization, the content was taken out and found to be a transparent liquid. This was filtered, and the concentration was adjusted to 60% (solid content, the same applies hereinafter) with butyl acetate to obtain a fluororesin paint varnish. Table 1 shows the monomer composition, solvent, and physical properties of the obtained fluoropolymer used in the polymerization (Example 1).

Polymerization was carried out in the same manner with the composition shown in Table 1 (Examples 2 to 5). In all cases, after the polymerization was completed, the content was taken out and found to be a transparent liquid. This was filtered, and the concentration was adjusted to 60% (solid content, the same applies hereinafter) with butyl acetate to obtain a fluororesin paint varnish. Table 1 shows the monomer composition, solvent, and physical properties of the obtained fluoropolymer used in the polymerization.

[0044]

[Table 1]

CTFE: chlorotrifluoroethylene AAA: allyl acetoacetate tBPAC: t-butyl peroxyoxyallyl carbonate εCAE: ε-caprolactone modified monoallyl ether VAc: vinyl acetate GMAE: glycerin monoallyl ether VPv: vinyl pivalate HBVE: hydroxybutyl Vinyl ether V9: Verzatic vinyl 9-acid EGMAE: Ethylene glycol monoallyl ether EVE: Ethyl vinyl ether UA: Undecylenic acid CHVE: Cyclohexyl vinyl ether DVAd: Divinyl adipate BuAC: Butyl acetate MMA: Methyl methacrylate EHMA: Acrylic acrylate Ethyl acid [Comparative Example 1] In the same manner as in Example 1, It was polymerized fluoropolymer without the use of carbon acid divinyl ester. After the polymerization, the content was taken out and found to be a transparent liquid. This is filtered and butyl acetate 60%
(Solid content, the same applies hereinafter) to obtain a varnish of a fluororesin paint with the concentration adjusted. The copolymer contained in this varnish has a small weight average molecular weight (Mw), and Mw and a number average molecular weight (Mn).
Was 3.0. Table 1 shows the monomer composition, solvent, and physical properties of the obtained fluoropolymer used in the polymerization.

Examples 6 to 9 11 g (2.0 mol%) of t-butyl peroxyallyl carbonate and 52 g (19.8 mol%) of vinyl acetate were placed in a 2.0-liter SUS autoclave equipped with a magnetic stirrer. ), 38 g (7.0 mol%) of versatic vinyl 9 acid, 31 g (10 mol%) of ethylene glycol monoallyl ether, 6 g (1 mol%) of undecylenic acid, ethyl vinyl ether 1
1 g (5 mol%), cyclohexyl vinyl ether 16
g (4 mol%), ε-caprolactone-modified monoallyl ether 10 g (1 mol%) divinyl adipate 1.2 g
(0.2 mol%), t-butyl peroxypivalate 2
g, 5 g of celite, and 600 g of butyl acetate, and the mixture was degassed by repeating degassing and replacement with nitrogen gas three times, and then 175 g (50 mol%) of chlorotrifluoroethylene was charged.
Polymerization was carried out at 5 ° C. for 18 hours.

Next, unreacted monomers were degassed, and 133 g of methyl methacrylate, 158 g of ethylhexyl methacrylate and 9 g of ethyl acrylate were added under reduced pressure.
Graft polymerization was performed at 0 ° C. for 6 hours. After the polymerization, the content was taken out and found to be a transparent liquid. After filtration, the concentration was adjusted to obtain a transparent fluororesin paint varnish having a solid content of 55%. Table 2 shows the monomer composition, solvent, and physical properties of the obtained fluoropolymer used in the polymerization (Example 6).

Similarly, polymerization was carried out with the composition shown in Table 2 (Examples 7 to 9). In all cases, after the polymerization was completed, the content was taken out and found to be a transparent liquid. This was adjusted to a concentration of 55% (solid content, hereinafter the same) with butyl acetate to obtain a varnish of a fluororesin paint. Table 2 shows the monomer composition, solvent, and physical properties of the obtained fluoropolymer used in the polymerization.

[0049]

[Table 2]

Comparative Example 2 In the same manner as in Example 6, Table 2
In the composition shown in the following, a fluorine copolymer was polymerized without using dicarboxylic acid divinyl ester. After the polymerization, the content was taken out and found to be a transparent liquid. This is 55
% (Solid content, the same applies hereinafter) to obtain a varnish of a fluororesin paint. The copolymer contained in this varnish has a small weight average molecular weight (Mw), and Mw and a number average molecular weight (Mw).
The ratio of n) was 3.7. Table 1 shows the monomer composition, solvent, and physical properties of the obtained fluoropolymer used in the polymerization.

[Application Example 1] 100 parts of titanium oxide CR-90 was dispersed in 100 parts of the fluororesin paint varnish obtained in Example 1 in terms of solid content in 100 parts by mill, and TPA100 (hexamethylene diisocyanate trimer manufactured by Asahi Chemical Industry Co., Ltd.) was used. Body) 1
5 parts were spray-coated on an aluminum plate (1 mm thick) and a polyvinylidene fluoride-based baked coating film (Kyner). After curing at room temperature (about 25 ° C) for 5 days,
The film thickness was about 43 microns. Accelerated weather resistance, pencil hardness, stain resistance test (color difference) due to outdoor exposure, DuPont impact test, flex resistance test, and boiling of paint film on polyvinylidene fluoride-based baked paint film (kynar) on aluminum plate An adhesion test was performed. Table 3 shows the results.

[0052]

[Table 3]

[Application Examples 2 to 9 and Comparative Application Examples 1 to 2] The fluororesin paint varnishes obtained in Examples 2 to 9 and Comparative Examples 1 and 2 were coated in the same manner as in Application Example 1 with a coating film of 40 to 50 microns. And each test was performed. Table 3 shows the results.

The method for evaluating the coating film is shown below. -Weather resistance: accelerated test (60-degree gloss retention before and after the test) by 5000 hours (A) or 10000 hours (B) of sunshine weatherometer. -Pencil hardness: Tested according to JIS K5400. -Color difference: Stain resistance test based on JIS-8730. After 6 months of outdoor exposure, color difference (ΔE) before and after exposure was measured. Exposure location: Kawagoe City, Saitama Prefecture. -PVDF adhesion: Boiling adhesion test. A PVDF coating is prepared as an undercoat to prepare a coating, which is boiled in boiling water for 5 hours. After that, adhesion was judged by a coin scratch test.

○ Peeling off at the interface of top coat / undercoat at all, △ peeling off at the interface with coin scratch, × blistering or peeling off at boiling. -Impact resistance: DuPont type impact resistance test. JISK5400
Tested in accordance with.

○ No peeling △ Fair peeling × Peeling. -Flex resistance: 2 diameter in accordance with JIS K5400 test method
Using a mandrel of mm, observe the bent surface for cracks.

○ No change △ Some cracks × cracks or cracks

[0058]

The fluorocopolymer according to the present invention exhibits a high solvent solubility even if it contains a large amount of a high molecular weight compound by increasing the weight average molecular weight and broadening the molecular weight distribution. The resulting coating film has the effect of simultaneously satisfying impact resistance, adhesion, stain resistance, bending workability, and the like.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08F 259/08 C08F 259/08 C09D 127/12 C09D 127/12 151/00 151/00 (72) Inventor Kentaro Tsutsumi Saitama 2805 Imafukunakadai, Kawagoe Prefecture, Japan F-term in Chemical Research Laboratories, Central Glass Co., Ltd. (Reference) BB01 BB02 CA02 DA02 DA03 DA04 DA07 DA08 DA10 DA12 DA14 DA15 EA08 GA08 GA09 4J038 CD091 CD101 CD111 CD121 CD131 CE051 CF041 CF091 CF101 CG031 CG061 CG071 CG081 CG141 CG151 CH021 CH031 CH041 GA141 GA03 GA03 DM03 AC23P AC24P AC26P AC27P AC31P AE01S AE09Q AE10Q AE18Q AE19Q AE64R AE71R AG01S AG08Q AG15Q AJ01Q AJ02Q AJ08Q AJ09Q AK32Q AL08Q AL16Q AL36Q AL44Q AL63R AL75R BA16Q BA02Q BA03Q BA02Q BA03Q BA02Q BA16Q BA02Q BA16Q BA02Q 1

Claims (12)

[Claims] (1) a number average molecular weight obtained by polymerizing a monomer having a crosslinkable site with a fluoroolefin and another monomer is 1,000 to 40,000, and a weight average molecular weight is 100,
A fluorine-based copolymer having a weight-average molecular weight / number-average molecular weight ratio of 4 or more; 2. The monomer according to claim 1, wherein the monomer having a crosslinking site is a monomer having a hydroxy group, a carboxyl group, an organic silicon group having a hydrolyzable group, a β-ketoester group or an epoxy group. Fluorine copolymer. 3. The monomer having a crosslinking site is an allyl ether, a vinyl ether, a crotonic acid-modified compound, a (meth) acrylate, an unsaturated carboxylic acid, a vinyl ester or a monoester of an unsaturated carboxylic acid. The fluorinated copolymer according to claim 1. 4. The other monomer includes a monomer having two or more polymerizable unsaturated bonds in a molecule, and substantially all of the polymerizable unsaturated bonds of the monomer are subjected to a polymerization reaction. The fluorinated copolymer according to any one of claims 1 to 3, obtained by a given copolymerization reaction. 5. A monomer having two or more polymerizable unsaturated bonds in a molecule is present in an amount of 0.001 to 5 mol% based on the total amount of the starting monomer.
The fluorine-based copolymer according to claim 4, which is: 6. The method according to claim 4, wherein the monomer having two or more polymerizable unsaturated bonds in the molecule is a dicarboxylic acid divinyl ester, divinyl ether or diallyl ether. Fluorine copolymer. 7. The fluorinated copolymer according to claim 4, wherein the monomer having two or more polymerizable unsaturated bonds in the molecule is divinyl adipate. 8. A polymer obtained by polymerizing a monomer having a crosslinkable site with a fluoroolefin and another monomer, and further graft-polymerizing a graft monomer with a number average molecular weight of 1 000-40,000, weight average molecular weight of 1
A fluorine-based graft copolymer having a weight-average molecular weight / number-average molecular weight ratio of at least 4,000 to 500,000. 9. The polymer according to claim 1, wherein the other monomer contains a monomer having two or more polymerizable unsaturated bonds in the molecule, and substantially all of the polymerizable unsaturated bonds of the monomer. 9. The fluorine-based graft copolymer according to claim 8, wherein is a polymer obtained by a copolymerization reaction exerting on the polymerization reaction. 10. The method according to claim 8, wherein the graft polymerization is carried out by using 1 to 200 parts by weight of a (meth) acrylate with respect to 100 parts by weight of the polymer as a graft monomer. A fluorine-based graft copolymer of 11. The fluorine-based copolymer according to claim 1 or 2 or the fluorine-based graft copolymer according to claim 3 is included in these copolymers. A modified fluorine-based copolymer obtained by reacting a compound having a reactive functional group and a trialkoxysilyl group with a crosslinking site. 12. The fluorine-based copolymer according to any one of claims 1 to 7, the fluorine-based graft copolymer according to any one of claims 8 to 11, or the modified fluorine-based copolymer according to claim 11. A fluororesin coating composition comprising a copolymer and a solvent in an amount necessary to dissolve the copolymer.