JPH07188604A - Fluororesin coating composition - Google Patents

Abstract

PURPOSE:To obtain a stain-resistant fluororesin coating compsn. which can keep an excellent appearance even in long-term outdoor use while maintaining a weatherability. CONSTITUTION:A fluororesin compsn. has an OH value of 90 to 150mg-KOH/g, and comprises 100 pts. wt. compd. CAL, 0.1-40 pts.wt. compd. [B] and 0.1-20 pts.wt. compd. [C]. The compd. [A] is a fluorine-contg. copolymer having a no.-average mol.wt. (calculated in terms of polystyrene) of 1,000 to 20,000 and an OH value of 70 to 140mg-KOH/g, and comprising 3 kinds of indispensable constituent units which are those of chlorotrifluoroethylene, a copolymerizable double-bond compd. and a copolymerizable ally or vinyl compd. contg. a hydroxyl group. The compd. [B] is a polyoxyethylene monoalkyl ether. The compd. [C] is at least one compd. selected from among glycerol, monofatty acid esters of glycerol, and glycerol monoalkyl ethers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororesin coating composition, and more particularly to a fluororesin coating composition excellent in stain resistance and weather resistance.

[0002]

2. Description of the Related Art Conventionally, fluororesin paints utilizing the excellent weather resistance of fluorocopolymers have been industrialized. Particularly recently, a solvent-soluble type fluorine-containing copolymer having a curing site has been synthesized (for example, JP-A-57-34107, JP-A-61-57609, etc.), and construction, automobile, chemistry It is widely applied as a weather resistant paint in the industrial field. In addition, water-based and powder-type paints, which place importance on the environment and suppress the emission of organic solvents, have been put into practical use. The main component of these paint resins is a fluorinated monomer such as chlorotrifluoroethylene, tetrafluoroethylene or vinylidene fluoride, and the use of a hydrocarbon-based monomer such as vinyl ester or vinyl ether as a copolymerization component makes the resin It has an increased solubility in a solvent.

However, recently, these solvent-soluble fluororesin coatings have been regarded as a serious problem because they are excellent in weather resistance but are easily soiled. As means for solving the problems, attempts have been made to increase the surface hardness of the coating film, addition of inorganic material powder, and the like. This fluororesin coating with increased surface hardness shows stain resistance in the carbon black adhesion test and the magic ink stain test, but it is still easy to stain in the actual exposure test, and it does not show gloss in the inorganic powder addition system. However, there is a drawback that it is difficult to remove, and the stain resistance has not been clearly improved.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a solvent which is excellent in stain resistance and maintains gloss even when used outdoors for a long time while maintaining the physical properties such as weather resistance and chemical resistance of the fluororesin coating material. To provide a fusible fluororesin paint.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies as to the above-mentioned problems, and as a result, have imparted hydrophilicity to a fluororesin coating composed of a chlorotrifluoroethylene-based solvent-soluble fluororesin and charged the same. In order to prevent the above, an attempt was made to blend a nonionic surfactant and also to add a glycerin-based compound, and it was found that excellent contamination resistance was obtained in an exposure test, and the present invention was achieved. Is.

That is, in the present invention, three kinds of constitutional units of chlorotrifluoroethylene as a compound [A], a copolymerizable double bond compound, and a copolymerizable allyl or vinyl compound containing a hydroxy group are essential. Number average molecular weight (polystyrene conversion) 1000 to 20000
Further, with respect to 100 parts by weight of the fluorine-containing copolymer having an OH value of 70 to 140 mgKOH / g (hereinafter, "parts by weight" is referred to as "parts"), 0.1 parts of polyoxyethylene monoalkyl ether as the compound [B] is used. 1 part selected from glycerin, glycerin monofatty acid ester and glycerin monoalkyl ether as compound [C]
A fluororesin composition containing 0.1 part or more and 20 parts or less of one or more compounds, wherein the OH value of the fluororesin composition is 90 to 150 mgKOH. .

The present invention will be described in detail below. The fluorine-containing monomer used for the compound [A] of the present invention is chlorotrifluoroethylene, and the existing composition ratio in the copolymer is not particularly limited, but 30 mol% to 65 mol% is preferable.
If it is 30 mol% or less, the weather resistance is not sufficient, and if it is 65 mol% or more, the solubility decreases, which is not preferable.

As the component copolymerizable with chlorotrifluoroethylene, vinyl ester (general formula CH ₂ = CHOC (= O)
R ₁ ), vinyl ether (general formula CH ₂ = CHOR ₂ ), allyl ether (general formula CH ₂ = CHCH ₂ OR ₃ ), vinylsilane [general formula
CH ₂ = CHOSi (OR ₄ ) ₃ ], a crotonic acid-modified compound and the like are preferable. In these compounds, R ₁ , R ₂ and R ₃ have 1 to 1 carbon atoms.
22 linear, branched or alicyclic alkyl groups, aromatic groups, groups containing an ester bond or an ether bond, or a combination thereof. On the other hand, R ₄ is hydrogen or an alkyl group. However, the three R ₄ bonded to Si do not necessarily have to be the same.

Specific examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate,
Vinyl isobutyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl myristate, vinyl laurate, vinyl palmitate, vinyl isocaproate, vinyl pivalate, vinyl stearate, Beover 9 (Showa Shell Sekiyu), Beover 10 (manufactured by Showa Shell Sekiyu KK), fatty acid vinyl esters such as isopropenyl acetate, isopropenyl propionate and isopropenyl caproate, fatty acid isopropenyl esters and vinyl benzoate, aromatic carboxylic acids such as pt-butyl vinyl benzoate. Examples thereof include acid vinyl esters. It is also possible to use two or more of these vinyl esters in combination. Examples of vinyl ethers include alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, and octadecyl vinyl ether; alicyclic vinyl ethers such as isobutyl vinyl ether, chloroethyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether; and isooctyl. Examples thereof include vinyl ether. In addition, the hydroxy group-containing vinyl ether described below can also be used instead of or together with these.

Examples of the allyl ether include alkyl allyl ethers such as ethyl allyl ether and butyl allyl ether, aromatic allyl ethers such as benzyl allyl ether, and allyl glycidyl ether and cyclohexyl allyl ether. Further, the hydroxy group-containing allyl ether described below may be used instead of or together with these.

As the vinyl silane, for example, linear or branched vinyl trialkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane and vinyltriisopropoxysilane, and substituents such as vinyltri (methoxyethoxy) silane are different. Vinyl silane etc. are mentioned.

The hydroxy group-containing allyl or vinyl compound used in the present invention is preferably the above-mentioned vinyl ester, vinyl ether or allyl ether having one or many hydroxy groups at the terminal or side chain. . For example, as allyl ether, ethylene glycol monoallyl ether, diethylene glycol monoallyl ether, triethylene glycol monoallyl ether, polyethylene glycol monoallyl ether, propylene glycol monoallyl ether,
Alkylene glycol monoallyl ethers such as ethylene glycol propylene glycol monoallyl ether and polyethylene glycol polypropylene glycol monoallyl ether, hydroxyalkyl allyl ethers and allyl alcohol such as hydroxybutyl allyl ether, and hydroxyethyl vinyl ether and hydroxypropyl vinyl ether as vinyl ether. Examples thereof include hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether. It is also possible to add monomers obtained by modifying the OH groups of these monomers with ε-caprolactone.

Further, in the fluorine-containing copolymer of the present invention, it is possible to introduce a carboxylic acid-containing unsaturated double bond compound as a copolymerization component in order to improve properties such as pigment dispersibility. The carboxylic acid-containing unsaturated double bond compound is not particularly limited, and examples thereof include a vinyl compound having a carboxyl group such as vinyl acetic acid, allyl acetic acid, crotonic acid, undecylenic acid, (meth) acrylic acid, maleic anhydride, and allyl. It is also possible to introduce a carboxyl group into the copolymer by reacting a compound or an acrylic compound, or a hydroxy group-containing allyl ether or vinyl ether after polymerization with succinic anhydride or the like.

As a method for polymerizing the above-mentioned multi-component fluorine-containing copolymer [A], an ordinary radical polymerization method can be adopted in its production, and its polymerization form is solution polymerization,
Suspension polymerization and emulsion polymerization are possible. The temperature of the polymerization step depends on the radical polymerization initiator used, but is usually 0 to 1
It is 30 ° C. The solvent is not particularly limited, and examples thereof include water, alcohols such as t-butanol and ethyl alcohol, saturated hydrocarbons such as n-hexane and n-heptane, aromatic hydrocarbons such as toluene and xylene,
Fluorine-based compounds such as trichlorotrifluoroethane and dichlorotetrafluoroethane, ketone-based compounds such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and ester-based compounds such as ethyl acetate and butyl acetate can be used. Examples of the radical initiator include dicarbonates such as diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate and di-2-ethylhexyl peroxydicarbonate, or n-heptafluorobutyric peroxide, lauroyl. Diacyl peroxides such as peroxypivalate and t-butyloxy neodecanoate, alkyl peroxides such as di-t-butyl peroxide and t-butylcumyl peroxide, and water-soluble peroxides such as succinic acid peroxide. Ordinary radical initiators such as azo compounds such as azoisobutyronitrile can be used.

As the molecular weight of the fluorine-containing copolymer thus polymerized, that is, the compound [A], it can be used in the range of 1,000 to 20,000 depending on the strength and flexibility of the coating film required, but it is 3,000. ~ 12000 is more preferable. When it is 1000 or less, the weather resistance and flexibility of the coating film are deteriorated, and when it is 20000 or more, the viscosity becomes high when it is made into a coating material, and it is difficult to handle.

The OH value of the compound [A] is 7
It is preferably in the range of 0 to 140 mgKOH / g. When it is 70 or less, crosslinking with the compounds [B] and [C] tends to be insufficient, and when it is 140 or more, the weather resistance is deteriorated.

The compound [B] polyoxyethylene monoalkyl ether which can be used in the present invention is mixed for the purpose of imparting hydrophilicity to the coating film surface. The polyoxyethylene monoalkyl ethers have the general formula R ₅ - is (CH ₂ CH ₂ O) a compound represented by n-H, R ₅ is an alkyl or alkenyl group of 9-22 carbon atoms, It is preferable that n is 3 to 12. The hydrophilicity imparted to the coating film depends on the HLB value of polyoxyethylene monoalkyl ether (a scale representing hydrophilicity and hydrophobicity), and effective stain resistance is obtained when the HLB value is in the range of 5 to 15. . When the HLB value is low, the coating film becomes lipophilic and it becomes easy to adsorb oily stains. Further, when the HLB is high, it becomes hygroscopic and easily adsorbs hydrophilic dirt. On the other hand, when the carbon number of R ₅ is 9 or less, the solubility in the paint is poor, and when it is 22 or more, the oil stains adsorbed are difficult to be released. Further, when n is 3 or less, the polyoxyethylene monoalkyl ether has a low molecular weight so that the coating film cannot have sufficient weather resistance, and when n is 13 or more, the water resistance of the coating film is poor and the weather resistance is deteriorated. As a result, it becomes difficult to remove the adsorbed hydrophilic dirt. The terminal hydroxy group is a site that can be cured by a curing agent added to the coating composition of the present invention, for example, a curing agent such as an isocyanate compound or a melamine compound.

The amount of polyoxyethylene monoalkyl ether added is 0.1 based on 100 parts of compound [A].
The range is from 40 parts to 40 parts. If less than 0.1 parts,
Sufficient hydrophilicity is not achieved, and if it is 40 parts or more, the coating film becomes hygroscopic and the weather resistance deteriorates, which is not preferable.

The glycerin compound [C] used in the present invention is mixed for the purpose of improving the weather resistance of the coating film.
That is, since the aforementioned polyoxyethylene monoalkyl ether has only one hydroxy group in the molecule, uncrosslinked molecules in which the crosslinking reaction with the curing agent does not proceed completely are likely to be present in the coating film. The present invention is a mixture of a glycerin-based compound as the compound [C] for the purpose of reducing the uncrosslinked molecules as much as possible, increasing the film strength, and improving the weather resistance. Therefore, for this purpose, it is preferable that two or more hydroxy groups are present in one molecule of the glycerin-based compound. For example, the general formula

[0020]

[Chemical 1]

(2 of R ₆ , R ₇ and R ₈ are hydrogen, and one is a linear or branched saturated or unsaturated alkyl group having 1 to 22 carbon atoms or an acyl group. )
Is a compound represented by. When any of R ₆ , R ₇ and R ₈ has 23 or more carbon atoms, the coating film becomes lipophilic, which causes a drawback of easily adsorbing oily stains, which is not preferable.
Specifically, for example, glycerol monofatty acid esters such as glycerol monoacetate, glycerol monobutyrate, glycerol monolaurate, glycerol monooleate, glycerol monopalmitate, glycerol monostearate, glycerol monomethyl ether, glycerol monoethyl ester. Glycerol monoalkyl ethers such as ether, glycerol monobutyl ether and glycerol monostearyl ether are preferably used. Further, when the resin OH value of the fluorine-containing copolymer is relatively high, glycerol difatty acid ester such as glycerol diacetate having one hydroxy group or glycerol dialkyl ether may be used in some cases.

The mixing ratio of these glycerin compounds may be 0.1 part or more and 20 parts or less with respect to 100 parts of the fluorocopolymer of the fluororesin coating material. If it is less than 0.1 part, the addition concentration is low and it does not react sufficiently with the curing agent, so that the effect of addition is hardly exhibited and the stain resistance does not last long. If it is 20 parts or more, weather resistance, water resistance, hardness, etc. are deteriorated, which is not preferable.

In the present invention, the compound [A] is used as described above.
[B] and [C] are blended, but all of these compounds contain a hydroxy group in the molecule and bridge to one component by the reaction with the curing agent. Therefore, in the present invention, the total OH value used for this crosslinking reaction is important. That is, the total OH value of the fluororesin coating composition prepared by mixing [A], [B] and [C] is 90 to 150 mgK.
The range of OH / g is preferably adopted, and excellent stain resistance and weather resistance can be obtained. The reason for this is that the composition of the present invention mixes a fluorine-containing copolymer as a main component with a hydrophilic compound having a relatively low molecular weight, so that when the OH value is low, that is, when it is 90 or less, the crosslinking density is insufficient and the contamination component is It is presumed that is easily penetrated into the film and the dirt is hard to be removed. On the other hand, when it is 150 or more, the impact strength and weather resistance of the film are deteriorated.

The fluororesin coating composition of the present invention is used as a coating material in various embodiments, and as the type of coating material, the resin is dissolved in an aromatic type, ester type, ether type, ketone type, etc. single or mixed solvent. It is used as a solvent-based, water-based paint that mainly uses water, or as a powder-based paint.

Further, other additives such as an ultraviolet absorber, a light stabilizer, a rust preventive, a fungicide and a dispersant can be added depending on the use. Hereinafter, the present invention will be specifically described with reference to Examples and the like.

[0026]

【Example】

Reference Example 1 [Production Example of Fluorine-Containing Copolymer] Xylene 320 g, vinyl acetate 100 g, vinyl pivalate 5 were placed in a SUS 2L autoclave equipped with a magnetic stirrer.
6 g, ethylene glycol monoallyl ether 120
g, 5.5 g of vinyl acetic acid and 6 g of perloyl NPP (manufactured by NOF Corporation) were charged, and after degassing with nitrogen gas, 390 g of chlorotrifluoroethylene was charged and polymerization was carried out at 45 ° C. for 20 hours. The obtained resin solution was filtered to obtain a coating varnish of the fluorine-containing copolymer. The molecular weight of this fluorinated copolymer (measured by gel permeation method and expressed in terms of polystyrene, the same applies hereinafter) is 6100, resin OH
The value was 110 mg KOH / g.

Reference Example 2 [Production Example of Fluorine-Containing Copolymer] Xylene 3 was added to an SUS autoclave equipped with a magnetic stirrer.
Charge 20 g, cyclohexyl vinyl ether 140 g, ethyl vinyl ether 190 g, hydroxybutyl vinyl ether 110 g, undecylenic acid 8.8 g, perloyl NPP (manufactured by NOF CORPORATION), and after degassing with nitrogen gas, charge 380 g of chlorotrifluoroethylene.
Polymerization was carried out at 45 ° C. for 22 hours. The obtained mixture was filtered to obtain a fluorinated copolymer coating varnish. Fluorine-containing copolymer has a molecular weight of 9700, resin OH value is 70 mgK
It was OH / g.

Reference Example 3 [Production Example of Fluorine-Containing Copolymer] Xylene 3 was added to an SUS autoclave equipped with a magnetic stirrer.
20 g, vinyl acetate 25 g, Beoper 9 (manufactured by Showa Sekiyu Shell) 250 g, hydroxybutyl vinyl ether 20
6 g, undecylenic acid 8.8 g, perbutyl PV (manufactured by NOF CORPORATION) were charged, and after degassing with nitrogen gas, 380 g of chlorotrifluoroethylene was charged, and at 24 ° C at 55 ° C.
Polymerization was carried out for a time. The obtained mixture was filtered to obtain a fluorinated copolymer coating varnish. The fluorine-containing copolymer had a molecular weight of 5,400 and a resin OH value of 138 mgKOH / g.

Reference Example 4 [Production Example of Fluorine-Containing Copolymer] Xylene 3 was added to an SUS autoclave equipped with a magnetic stirrer.
20 g, vinyl acetate 120 g, vinyl pivalate 86
g, 65 g of ethylene glycol monoallyl ether, 5 g of vinyl acetic acid and 6 g of perloyl NPP (manufactured by NOF CORPORATION) were charged, and after degassing with nitrogen gas, 380 g of chlorotrifluoroethylene was charged and polymerization was carried out at 45 ° C. for 20 hours. The obtained resin solution was filtered to obtain a coating varnish of the fluorine-containing copolymer. The molecular weight of this fluorocopolymer is 7
Although it was 800, the resin OH value was as low as 60 mgKOH / g.

Reference Example 5 [Production Example of Fluorine-Containing Copolymer] Xylene 3 was added to an SUS autoclave equipped with a magnetic stirrer.
20 g, 140 g of vinyl acetate, 100 g of vinyl butyrate, 230 g of ethylene glycol monoallyl ether, 6 g of vinyl acetic acid, 9 g of perbutyl PV (manufactured by NOF Corporation) were charged, and after degassing with nitrogen gas, 380 g of chlorotrifluoroethylene was charged, and 45 ° C. Polymerization was carried out for 20 hours.
The obtained resin solution was filtered to obtain a coating varnish of the fluorine-containing copolymer. The molecular weight of this fluorine-containing copolymer is 390.
Although it was 0, the resin OH value was as high as 170 mgKOH / g.

Example 1 In a fluororesin coating material using the fluorocopolymer (compound [A]) prepared in Reference Example 1, polyoxyethylene monooleyl ether (compound [B] was added to 100 parts of the copolymer). ]) (Nippon Emulsifier: Newcol-12
10, HLB = 12.4), 10 parts of glycerol monooleate (compound [C]) (manufactured by Kao: Reodol MO)
-60) was added in an amount of 5 parts to prepare a base material for a fluororesin coating which was a xylene solution.

Next, 100 parts of titanium oxide (white pigment) was added to 100 parts of the solid content of the main agent, and the resulting mixture was sufficiently mill-dispersed to obtain a white enamel. 37 parts of Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a curing agent was added to the white enamel of the fluororesin paint, and about 0.0% was added to the aluminum plate.
It was spray coated to a thickness of 4 mm. The coated plate was allowed to undergo a curing reaction at 23 ° C. for 1 week, then subjected to a stain resistance test by outdoor exposure for 6 months and an accelerated weather resistance test with a sunshine weatherometer for 4000 hours. The results are shown in Table 1.

The stain resistance was determined by the color difference (ΔE) before and after outdoor exposure according to JIS-Z8730 (color difference display method), and the weather resistance was determined by the 60% gloss retention before and after the accelerated test.

Examples 2 to 7 Fluorine-containing copolymer (compound [A]) as in Example 1
Fluororesin paint using Newcol-1210
(Compound [B]) and glycerol monooleate (Compound [C]) (Reodol MO-60) were added at the ratios shown in Table 1 to prepare the main component of the fluororesin coating.

Next, after making a paint into a white enamel in the same manner as in Example 1, a curing agent was added so that the amount of isocyanate corresponding to the OH value was adjusted (the ratio of the number of moles of OH groups and isocyanate groups was about 1). The same shall apply hereinafter), and an aluminum plate was coated to carry out a stain resistance test and an accelerated weather resistance test.
The results are shown in Table 1.

Example 8 Fluorine-containing copolymer (compound [A]) as in Example 1
Polyoxyethylene monooleyl ether (Compound [B]) (Nippon Emulsifier: Ne
wcol-1105, HLB = 10.8), and glycerol monooleate (compound [C]) (Reodol MO-60) were added at the ratios shown in Table 1 to prepare the main component of the fluororesin coating material.

Next, after making a paint into a white enamel in the same manner as in Example 1, a curing agent is added so that the amount of isocyanate corresponding to the OH value is reached, and an aluminum plate is coated, followed by a stain resistance test and accelerated weathering resistance. The test was conducted. The results are shown in Table 1.

Examples 9 to 12 Fluorine-containing copolymer (compound [A]) as in Example 1
Polyoxyethylene monooleyl ether (Compound [B]) (Nippon Emulsifier: Ne
wcol-1610 or -1105) and glycerol monostearate (compound [C]) (manufactured by Tokyo Kasei) were added at the ratios shown in Table 1 to prepare the main component of the fluororesin coating material.

[0039] Next, after making a paint into a white enamel in the same manner as in Example 1, a curing agent is added so that the amount of isocyanate corresponding to the OH value is reached, and an aluminum plate is coated, and a stain resistance test and accelerated weather resistance are performed. The test was conducted. The results are shown in Table 1.

[0040]

[Table 1]

Compounds used Compound [A]: Fluorine-containing copolymer Compound [B]: Polyoxyethylene monoalkyl ether Newcol-1105, 1210, 1610 manufactured by Nippon Emulsifier was used Compound [C]: Glycerin compound GMO = Glycerol monooleate (Kao: Leodol MO-60) GMS = Glycerol monostearate (Tokyo Kasei) GDAc = Glycerol diacetate (Tokyo Kasei) GTrO = Glycerol trioleate (Tokyo Kasei) Evaluation method Contamination resistance: Color difference around 6 months of outdoor exposure (JIS-Z87
30) Exposure location, Kawagoe City, Saitama Prefecture Weather resistance: Acceleration test by sunshine weatherometer 4000 hours 60 degree gloss retention before and after the test Comparative Examples 1 to 3 The fluorine-containing copolymers prepared in Reference Example or compound [A ], And white enamel was prepared according to Example 1 without adding the compounds [B] and [C].

Next, according to the method of Example 1, the curing agent was OH.
In addition to the amount of isocyanate corresponding to the valence, it was coated on an aluminum plate and subjected to a stain resistance test and an accelerated weather resistance test. The results are shown in Table 1.

Comparative Examples 4 to 9 Compound [A] was used as a fluorine-containing copolymer, or
Compounds [B] and [C] were mixed in the proportions shown in Table 1, and white enamel was produced according to Example 1. Comparative Example 4
Is not added with the compound [C], Comparative Example 5 is not added with the compound [B], Comparative Example 6 is with a large amount of the compound [B], Comparative Example 7 is with the compound [B] being polyoxyethylene. In the case of nonyl phenyl ether, Comparative Example 8 has a relatively low OH value of the compound [A], and when glycerol diacetate is used in the compound [C], Comparative Example 9 has a hydroxy group in the molecule of the compound [C]. This is the case of using a glycerin compound that does not have it.

Then, according to the method of Example 1, OH was added to the curing agent.
The amount of isocyanate corresponding to the valence was added, and an aluminum plate was coated to carry out a stain resistance test for 6 months and an accelerated weather resistance test. The results are shown in Table 1.

Comparative Examples 10 and 11 Compounds [B] and [C] were added to the fluorine-containing copolymers prepared in Reference Examples 4 and 5 as compounds [A], and white enamel was prepared according to Example 1. Comparative Example 10 is a case where the resin OH value of the compound [A] is low, and Comparative Example 11 is a case where the resin OH value of the compound [A] is high and the total OH value after mixing is high.

Then, according to the method of Example 1, the curing agent was OH.
In addition to the amount of isocyanate corresponding to the valence, it was coated on an aluminum plate and subjected to a stain resistance test and an accelerated weather resistance test. The results are shown in Table 1.

[0047]

[Table 2]

See Table 1 for the symbols and evaluation methods in the table.

[0049]

INDUSTRIAL APPLICABILITY In each of the coated aluminum sheets of Examples 1 to 12 using the composition for fluororesin coating prepared by adding polyoxyethylene monoalkyl ether and glycerin, glycerin fatty acid ester or glycerin monoalkyl ether, As compared with the coated aluminum plate of Comparative Example, the weather resistance and the stain resistance represented by the gloss retention rate were remarkably improved.

Claims (4)

[Claims] 1. A number average which essentially comprises three kinds of constitutional units of chlorotrifluoroethylene as a compound [A], a copolymerizable double bond compound, and a copolymerizable allyl or vinyl compound containing a hydroxy group. Molecular weight (polystyrene conversion) 1000 to 20000 and OH number 70 to 1
With respect to 100 parts by weight of 40 mg KOH / g fluorine-containing copolymer, 0.1 part or more and 40 parts or less of polyoxyethylene monoalkyl ether as the compound [B], glycerin, glycerin monofatty acid ester, glycerin mono as the compound [C] A fluororesin composition containing 0.1 part or more and 20 parts or less of one or more compounds selected from alkyl ethers, wherein the OH value of the fluororesin composition is 90 to 150 mgKOH.
A composition for a fluororesin coating, which is 2. The fluororesin coating composition according to claim 1, wherein the compound [B] has a repeating number n of oxyethylene units of a polyoxyethylene chain of 3 to 12. 3. The compound [C] is a mono-fatty acid ester of glycerin, wherein the acyl group is a linear or branched saturated or unsaturated acyl group having 1 to 22 carbon atoms. The fluororesin coating composition according to claim 1. 4. The compound [C] is a monoalkyl ether of glycerin, wherein the alkyl group is a linear or branched saturated or unsaturated alkyl group having 1 to 22 carbon atoms. The fluororesin coating composition according to claim 1.