WO2021085531A1 - Fluorine-containing polymer and curable composition - Google Patents

Abstract

Provided is a fluorine-containing polymer that exhibits an excellent heat resistance. The fluorine-containing polymer is characterized by comprising a polymerization unit based on a fluorine-containing vinyl monomer (1) and a polymerization unit based on a monomer (2) represented by the following general formula (2) (in the formula, X^B is H or CH₃), and having a glass transition temperature of at least 40°C.

Description

Fluororesin-containing polymer and curable composition

The present disclosure relates to fluoropolymers and curable compositions.

Fluororesin-containing polymers utilize various excellent properties such as water repellency, oil repellency, heat resistance, and chemical resistance, and are heat resistant to powder paints, various molded products such as electronic devices, vehicles, and other electric wires. It is used in various products that require. In particular, coating films, molded products, etc. obtained from powder paints may be exposed to high temperatures not only during manufacturing but also during use, so the fluoropolymer used as a raw material is required to have excellent heat resistance. And various studies have been conducted.

By the way, in Patent Document 1, the ratios based on the essential constituent monomers and their total amount are (a) fluoroolefin: 5 to 70 mol%, and (b) (meth) acrylic acid alkyl ester: 20 to. For room temperature curable paints consisting of 80 mol%, (c) a specific organic silicon compound having an olefinically unsaturated bond and a hydrolyzable group: 1 to 20 mol% of a fluorine-containing copolymer and a curing accelerator. The composition is described. However, Patent Document 1 does not describe a composition for powder coating materials, and only describes a fluorine-containing copolymer having a low glass transition temperature.

Japanese Unexamined Patent Publication No. 9-302301

The present disclosure provides a fluoropolymer having excellent heat resistance.

In the present disclosure, the polymerization unit based on the fluorine-containing vinyl monomer (1) and the following general formula (2):

A fluoropolymer containing a polymerization unit based on the monomer (2) represented by ( ^{X B} is H or CH _{3 in the formula) and having a glass transition temperature of 40 ° C. or higher.} provide.

The polymerization unit based on the monomer (2) is preferably 10 mol% or more based on the total polymerization units.

The polymerization unit based on the fluorine-containing vinyl monomer (1) is preferably 10 mol% or more based on the total polymerization units.

The fluorine-containing vinyl monomer (1) is at least one selected from the group consisting of vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, hexafluoropropylene and perfluoro (alkyl vinyl ether). Is preferable.

The fluoropolymer of the present disclosure preferably further contains a polymerization unit based on the monomer (3), which is at least one selected from the group consisting of vinyl ester monomers and vinyl ether monomers.

The above-mentioned monomer (3) has the following formula (A):
_{CH 2 = CH-O-C} (= O) -R A (A)
(In the formula, ^RA is an alkyl group having 1 to 4 carbon atoms or a phenyl group which may have a substituent.) Is preferably a monomer represented by.

The fluoropolymer of the present disclosure preferably further contains a polymerization unit based on the curable functional group-containing monomer (4).

The curable functional group-containing monomer (4) is preferably a monomer containing a carboxyl group or a hydroxyl group.

The curable functional group-containing monomer (4) is preferably at least one monomer selected from the group consisting of acrylic acid, crotonic acid, itaconic acid, citraconic acid, methacrylic acid, and hydroxybutyl vinyl ether.

The polymerization unit based on the curable functional group-containing monomer (4) is preferably 1 mol% or more based on the total polymerization units.

The fluoropolymer preferably has a number average molecular weight of 1000 to 500,000.

The present disclosure also provides a curable composition comprising the above fluoropolymer.

The curable composition of the present disclosure preferably further contains a curing agent.

The curing agent is preferably a primid-curing type or a triglycidyl isocyanurate-curing type curing agent.

The curable composition of the present disclosure preferably further contains a resin (B) different from the above-mentioned fluoropolymer.

The curable composition of the present disclosure preferably contains 1 to 1000 parts by mass of the resin (B) with respect to 100 parts by mass of the fluoropolymer.

The resin (B) is preferably at least one selected from the group consisting of acrylic resin, polyester resin and epoxy resin.

The curable composition of the present disclosure preferably further contains a curing accelerator.

The curable composition of the present disclosure is preferably a powder coating material.

The fluoropolymer of the present disclosure has excellent heat resistance.

The fluoropolymer of the present disclosure includes a polymerization unit based on the fluorovinyl monomer (1) (hereinafter, also referred to as “fluorine-containing vinyl monomer (1) unit”) and the following general formula (2):

By including ^{a polymerization unit based on the monomer (2) represented by (where X B} is H or CH ₃ in the formula) (hereinafter, also referred to as “monomer (2) unit”), the heat resistance is increased. Excellent. It also has excellent weather resistance.

Examples of the fluorine-containing vinyl monomer (1) include tetrafluoroethylene [TFE], vinylidene fluoride (vinylidene fluoride), chlorotrifluoroethylene [CTFE], vinyl fluoride, hexafluoropropylene [HFP], and perfluoro (). It is preferably at least one selected from the group consisting of (alkyl vinyl ether), and is more excellent in heat resistance, dispersibility, moisture resistance, flame retardancy, adhesiveness, chemical resistance, weather resistance, moisture resistance, etc. It is more preferably at least one selected from the group consisting of TFE, CTFE and HFP in that it is excellent, and it is at least one selected from the group consisting of TFE and HFP in that it does not contain chlorine. Is more preferable, and TFE is particularly preferable in that it is excellent in copolymerizability.
Examples of the perfluoro (alkyl vinyl ether) include perfluoro (methyl vinyl ether) [PMVE], perfluoro (ethyl vinyl ether) [PEVE], perfluoro (propyl vinyl ether) [PPVE], perfluoro (butyl vinyl ether) and the like. Is not limited to these.

Since the fluorine-containing vinyl monomer (1) unit is excellent in heat resistance, it is preferably 10 mol% or more, more preferably 20 mol% or more, and 30 mol% or more, based on the total polymerization units constituting the fluorine-containing polymer. More preferably mol% or more, even more preferably 40 mol% or more, particularly preferably 50 mol% or more, still preferably 90 mol% or less, more preferably 80 mol% or less, still more preferably 70 mol% or less, 60 More preferably mol% or less.

The fluoropolymer of the present disclosure contains the above-mentioned monomer (2) unit. By containing the above-mentioned monomer (2) unit, the fluoropolymer of the present disclosure has excellent heat resistance.

In the above general formula (2), X ^B is H or CH ₃ , and is preferably H.

Since the fluoropolymer of the present disclosure is more excellent in heat resistance, the monomer (2) unit is preferably 10 mol% or more based on the total polymerization unit. More preferably, it is 15 mol% or more, further preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 40 mol% or more. Moreover, since the weather resistance is excellent, the monomer (2) unit is preferably 90 mol% or less with respect to the total polymerization unit. It is more preferably 80 mol% or less, still more preferably 70 mol% or less, even more preferably 60 mol% or less, and particularly preferably 50 mol% or less.

In the fluoropolymer of the present disclosure, the molar ratio of the fluorovinyl monomer (1) unit / monomer (2) unit is preferably (10 to 90) / (10 to 90), and (20 to 80) / (. It is more preferably 20 to 80), and even more preferably (30 to 70) / (30 to 70).
In the fluorine-containing polymer of the present disclosure, the total content of the fluorine-containing vinyl monomer (1) unit and the monomer (2) unit is preferably 40 mol% or more, more preferably 45 mol% or more, based on the total polymerization units. Preferably, 50 mol% or more is further preferable, and 55 mol% or more is even more preferable. It may be 60 mol% or more, 70 mol% or more, or 80 mol% or more with respect to the total polymerization unit.

The fluoropolymer of the present disclosure is further described as a polymerization unit (hereinafter referred to as "other monomer unit") based on a monomer other than the fluorovinyl monomer (1) and the monomer (2) (hereinafter referred to as "other monomer"). ) May be included.
In the fluoropolymer of the present disclosure, the content of the other monomer units is preferably 60 mol% or less, more preferably 55 mol% or less, based on the total polymerization units of the fluoropolymer. It is more preferably 50 mol% or less, further preferably 45 mol% or less, and particularly preferably 40 mol% or less. Further, with respect to the total polymerization units of the fluoropolymer, 0 mol% or more is preferable, 0.1 mol% or more is more preferable, 0.5 mol% or more is further preferable, 1 mol% or more is preferable, and 5 mol% is preferable. The above is more preferable, 10 mol% or more is further preferable, 15 mol% or more is further preferable, and 20 mol% or more is particularly preferable.

Examples of the other monomer include a monomer (3) which is at least one selected from the group consisting of a vinyl ester monomer and a vinyl ether monomer, a curable functional group-containing monomer (4), and the like.

The fluoropolymer of the present disclosure further comprises a polymerization unit (hereinafter, also referred to as "monomer (3) unit") based on a monomer (3) which is at least one selected from the group consisting of a vinyl ester monomer and a vinyl ether monomer. It is one of the preferable forms to include. By containing the monomer (3) unit, the reactivity at the time of the polymerization reaction is high, so that it can be suitably used for powder coating materials.
The monomer (3) may be a non-fluorine monomer containing no fluorine atom.

Examples of the vinyl ester monomer of the monomer (3) include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatic acid, vinyl laurate, vinyl stearate, and vinyl cyclohexylcarboxylate. , Vinyl benzoate, para-t-butyl vinyl benzoate and the like.

As the vinyl ether monomer of the monomer (3), an alkyl vinyl ether containing no hydroxyl group and a carboxyl group is preferable, and methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, octadecyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, etc. Examples thereof include isopropyl vinyl ether and isobutyl vinyl ether, and among them, at least one selected from the group consisting of ethyl vinyl ether and cyclohexyl vinyl ether is preferable.

Since the monomer (3) has a high copolymerization reactivity, the following formula (A):
_{CH 2 = CH-O-C} (= O) -R A (A)
(In the formula, ^RA is a phenyl group which may have an alkyl group or a substituent having 1 to 4 carbon atoms.) It is preferable that it is a monomer represented by.

The ^{alkyl group of RA is} an alkyl group having 1 to 4 carbon atoms, and the alkyl group has preferably 1 to 2 carbon atoms, more preferably 1 carbon atom.

Examples of the ^{substituent that the phenyl group of RA} may have include an alkyl group having 1 to 4 carbon atoms, an alkoxyl group, a dialkylamino group and the like, and a t-butyl group is more preferable.

Since the glass transition temperature of the copolymer can be raised, the monomer (3) may be at least one selected from the group consisting of vinyl benzoate, parat-butyl vinyl benzoate, vinyl acetate and vinyl pivalate. It is preferable that there is at least one selected from the group consisting of vinyl benzoate, parat-butyl vinyl benzoate and vinyl acetate.

Since the reactivity with other resins is excellent, the monomer (3) unit may be 0 mol% or more, and 10 mol% or more, based on the total polymerization units of the fluoropolymer of the present disclosure. preferable. The monomer (3) unit is more preferably 20 mol% or more, more preferably 30 mol% or more, and more preferably 80 mol% or less, preferably 70 mol% or less, based on excellent heat resistance, based on the total polymerization unit. Is more preferable, and 60 mol% or less is further preferable.

In the fluoropolymer of the present disclosure, the polymerization unit based on the monomer represented by the above formula (A) is preferably 10 to 100 mol% with respect to the total of 100 mol% of the above-mentioned monomer (3) unit, and the above-mentioned formula. One of the preferred embodiments is that the polymerization unit based on the vinyl ester monomer other than the monomer represented by (A) and the vinyl ether monomer is 0 to 90 mol%. The polymerization unit based on the monomer represented by the above formula (A) is more preferably 20 to 90 mol%, more preferably 30 to 80 mol%, based on 100 mol% of the total of the above monomer (3) units. Is even more preferable, and 35 to 75 mol% is even more preferable, and 40 to 70 mol% is particularly preferable. The vinyl ester monomer other than the monomer represented by the above formula (A) and the polymerization unit based on the vinyl ether monomer are 10 to 80 mol% based on the total of 100 mol% of the monomer (3) unit. It is more preferably 20 to 70 mol%, even more preferably 25 to 65 mol%, and particularly preferably 30 to 60 mol%.

The monomer (3) preferably does not contain a hydroxyl group and a carboxyl group.

One of the preferred forms of the fluoropolymer of the present disclosure is that it further contains a polymerization unit based on the curable functional group-containing monomer (4) (hereinafter, also referred to as “monomer (4) unit”). By containing the monomer (4) unit, it can be suitably used as a material for powder coating materials.

The curable functional group-containing monomer (4) contains a curable functional group. The curable functional group is appropriately selected according to the ease of polymer production and the curing system. For example, a hydroxyl group (excluding the hydroxyl group contained in the carboxyl group; the same applies hereinafter), a carboxyl group, and -COOCO. Examples thereof include a group represented by −, a cyano group, an amino group, a glycidyl group, a silyl group, a silanate group and the like. Among them, at least one group selected from the group consisting of a hydroxyl group, a carboxyl group, a group represented by -COOCO-, an amino group, a cyano group, and a silyl group is preferable from the viewpoint of good curing reactivity. , At least one group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and a silyl group is more preferable, and at least one group selected from the group consisting of a hydroxyl group and a carboxyl group is further preferable. .. These curable functional groups are usually introduced into the fluoropolymer by copolymerizing a monomer having a curable functional group.

Examples of the curable functional group-containing monomer (4) include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, a hydrolyzable silyl group-containing monomer, an epoxy group-containing monomer, and an oxetane group-containing monomer. , One or more of these can be used. As the curable functional group-containing monomer (4), a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an epoxy group-containing monomer or an oxetane group-containing monomer is preferable, a hydroxyl group-containing monomer or a carboxyl group-containing monomer is more preferable, and a carboxyl group-containing monomer is more preferable. Is more preferable.

Examples of the hydroxyl group (-OH group) -containing monomer include hydroxyalkyl vinyl ether, hydroxyalkyl allyl ether, hydroxycarboxylic acid vinyl ester, hydroxycarboxylic acid allyl ester, and hydroxyalkyl (meth) acrylate.

Examples of the hydroxyalkyl vinyl ether include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, and 4-hydroxy-2-methylbutyl vinyl ether. , 5-Hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether and the like.

Examples of the hydroxyalkylallyl ether include 2-hydroxyethylallyl ether, 4-hydroxybutylallyl ether, glycerol monoallyl ether and the like.

Examples of the hydroxycarboxylic acid vinyl ester include vinyl hydroxyacetate, vinyl hydroxypropanoate, vinyl hydroxybutanoate, vinyl hydroxyhexanoate, vinyl 4-hydroxycyclohexylacetate and the like.

Examples of the allyl hydroxycarboxylic acid ester include allyl hydroxycarboxylate, allyl hydroxypropanate, allyl hydroxybutate, allyl hydroxyhexanoate, allyl 4-hydroxycyclohexylacetate and the like.

Examples of the hydroxyalkyl (meth) acrylate include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.

The carboxyl group (-COOH group) -containing monomer has the formula (B):
R ^1a R ^2a C = CR ^3a- (CH ₂ ) _n- COOH (B)
(In the formula, R ^1a , R ^2a and R ^3a are the same or different, and are all represented by a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms; n is an integer of 0 or more). Monomers can be mentioned. For example, acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid, pentenoic acid, hexenoic acid, heptonic acid, octene acid, nonene acid, decenoic acid, undecylene acid, dodecene acid, tridecenoic acid, tetradecene acid, pentadecene acid, hexadecenoic acid, Examples thereof include heptadecenoic acid, octadecene acid, nonadecenoic acid, acrylic acid, and 22-tricosenoic acid.
Examples of the monomer containing a carboxyl group include cinnamic acid, 3-allyloxypropionic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, maleic acid anhydride, fumaric acid, and fumaric acid monoester. Examples thereof include vinyl phthalate, vinyl pyromellitic acid, citraconic acid, mesaconic acid, and aconitic acid.

Examples of the amino group-containing monomer include aminovinyl _{ethers represented by CH 2} = CH-O- (CH ₂ ) _{x- NH 2} (x = 0 to 10); CH ₂ = CH-O-CO (CH ₂ ). amines represented by _{x -NH 2 (x = 1 ~} 10); other aminomethylstyrene, vinylamine, acrylamide, vinylacetamide, vinylformamide or the like.

Examples of the hydrolyzable silyl group-containing monomer include CH ₂ = CHCO ₂ (CH ₂ ) ₃ Si (OCH ₃ ) ₃ , CH ₂ = CHCO ₂ (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ , CH _2. = C (CH ₃ ) CO ₂ (CH ₂ ) ₃ Si (OCH ₃ ) ₃ , CH ₂ = C (CH ₃ ) CO ₂ (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ , CH ₂ = CHCO ₂ ( _{CH 2) 3 SiCH 3 (OC} 2 H 5) 2, CH 2 = C (CH 3) CO 2 (CH 2) 3 SiC 2 H 5 (OCH 3) 2, CH 2 = C (CH 3) CO 2 ( CH ₂ ) ₃ Si (CH ₃ ) ₂ (OC ₂ H ₅ ), CH ₂ = C (CH ₃ ) CO ₂ (CH ₂ ) ₃ Si (CH ₃ ) ₂ OH, CH ₂ = CH (CH ₂ ) ₃ Si (OCOCH ₃ ) ₃ , CH ₂ = C (CH ₃ ) CO ₂ (CH ₂ ) ₃ SiC ₂ H ₅ (OCOCH ₃ ) ₂ , CH ₂ = C (CH ₃ ) CO ₂ (CH ₂ ) ₃ SCH ₃ (N) (CH ₃ ) COCH ₃ ) ₂ , CH ₂ = CHCO ₂ (CH ₂ ) ₃ SiC H ₃ [ON (CH ₃ ) C ₂ H ₅ ] ₂ , CH ₂ = C (CH ₃ ) CO ₂ (CH ₂ ) ₃ SiC ₆ H ₅ [ON (CH ₃ ) C ₂ H ₅ ] _2nd grade (meth) acrylic acid esters; CH ₂ = CHSi [ON = C (CH ₃ ) (C ₂ H ₅ )] ₃ , CH ₂ = CHSi (OCH ₃ ) ₃ , CH ₂ = CHSi (OC ₂ H ₅ ) ₃ , CH ₂ = CHSiCH ₃ (OCH ₃ ) ₂ , CH ₂ = CHSi (OCOCH ₃ ) ₃ , CH ₂ = CHSi (CH ₃ ) ₂ (OC) ₂ H ₅ ), CH ₂ = CHSi (CH ₃ ) ₂ SCH ₃ (OCH ₃ ) ₂ , CH ₂ = CHSiC ₂ H ₅ (OCOCH ₃ ) ₂ , CH ₂ = CHSiCH ₃ [ON (CH ₃ ) C ₂ H ₅ ] _2. Vinyl silanes such as vinyl trichlorosilane or partial hydrolyzates thereof; trimethoxysilylethyl vinyl ether, triethoxysilylethi Examples thereof include vinyl ethers such as ruvinyl ether, trimethoxysilylbutyl vinyl ether, methyldimethoxysilylethyl vinyl ether, trimethoxysilylpropyl vinyl ether, and triethoxysilylpropyl vinyl ether.

Examples of the epoxy group-containing monomer include allyl glycidyl ether, 4-hydroxybutyl acrylate glycidyl ether, 3,4-epoxycyclohexylmethyl methacrylate and the like. Examples of the oxetane group-containing monomer include (3-ethyloxetane-3-yl) methyl acrylate. When the fluorine-containing monomer of the present disclosure contains an epoxy group / oxetane group-containing monomer, the total amount of the epoxy group-containing monomer and the oxetane group-containing monomer may be 0.1 to 10 mol% with respect to the total polymerization unit. It is preferably 0.5 to 5 mol%, more preferably 0.5 to 5 mol%. By using such an epoxy group-containing monomer or an oxetane group-containing monomer, a self-crosslinkable fluoropolymer can be obtained.

The curable functional group-containing monomer (4) includes acrylic acid, crotonic acid, itaconic acid, citraconic acid, methacrylic acid, hydroxybutyl vinyl ether, hydroxyethyl vinyl ether, and 2-hydroxyethyl acrylate, in particular from the viewpoint of reactivity. , 2-Hydroxyethyl methacrylate and 2-hydroxyethyl allyl ether are preferably at least one monomer selected from the group. More preferably, it is at least one monomer selected from the group consisting of acrylic acid, crotonic acid, itaconic acid, citraconic acid, methacrylic acid, and hydroxybutyl vinyl ether, and even more preferably acrylic acid, crotonic acid, and itaconic acid. It is at least one monomer selected from the group consisting of acid, citraconic acid, hydroxybutyl vinyl ether, and hydroxyethyl vinyl ether, and even more preferably acrylic acid, crotonic acid, itaconic acid, hydroxybutyl vinyl ether, and hydroxy. It is at least one monomer selected from the group consisting of ethyl vinyl ether.

The monomer (4) unit may be 0 mol% or more, preferably 1 mol% or more, based on the total polymerization unit. More preferably, it is 3 mol% or more, and further preferably 5 mol% or more. Further, since it is excellent in curability, the monomer (4) unit is preferably 20 mol% or less with respect to the total polymerization unit. More preferably, it is 15 mol% or less, and even more preferably 10 mol% or less.

Examples of the other monomer include non-fluorinated olefins that do not contain halogen atoms and hydroxyl groups.

Examples of the non-fluorinated olefin containing no halogen atom and hydroxyl group include ethylene, propylene, n-butene and inbutene.

The fluorine content of the fluoropolymer of the present disclosure is preferably 5% by mass or more from the viewpoint of weather resistance. It is more preferably 10% by mass or more, further preferably 15% by mass or more, and particularly preferably 20% by mass or more.
The fluorine content of the fluoropolymer can be determined by elemental analysis using an automatic sample combustion device.

The number average molecular weight of the fluoropolymer of the present disclosure is preferably 1000 to 500,000. When the number average molecular weight of the fluoropolymer is in such a range, it can be suitably used for powder coating materials from the viewpoint of weather resistance. The number average molecular weight of the fluoropolymer is more preferably 1,000 to 100,000, more preferably 3,000 to 50,000, and more preferably 5,000 to 20,000.
From the viewpoint of meltability, the number average molecular weight is preferably 50,000 or less, more preferably 30,000 or less, further preferably 20,000 or less, and even more preferably 10,000 or less.
The number average molecular weight of the fluoropolymer can be measured by gel permeation chromatography (GPC).

The glass transition temperature of the fluoropolymer of the present disclosure is 40 ° C. or higher. The glass transition temperature is more preferably 50 ° C. or higher, further preferably 55 ° C. or higher, even more preferably 60 ° C. or higher, particularly preferably 70 ° C. or higher, and particularly preferably 75 ° C. or higher. The glass transition temperature is preferably high, but from the viewpoint of processability, it is preferably 100 ° C. or lower.
The glass transition temperature is a value determined by the midpoint method from heat absorption in the second run using a DSC measuring device under the following conditions according to ASTM E1356-98.
Measurement conditions Temperature rise rate; 20 ° C / min
Sample amount; 10 mg
Heat cycle; -50 ° C to 150 ° C, temperature rise, cooling, temperature rise

One of the particularly preferred embodiments of the fluoropolymers of the present disclosure is 10-90 mol% fluorovinyl monomer (1) units, 10-80 mol% monomer (2) units, 0-80 mol% formula ( It includes the monomer unit represented by A). A more preferred embodiment comprises 20 to 80 mol% of fluorovinyl monomer (1) units, 10 to 70 mol% of monomer (2) units, and 10 to 60 mol% of monomer units represented by the formula (A). A more preferred embodiment is 30 to 70 mol% of fluorovinyl monomer (1) unit, 20 to 60 mol% of monomer (2) unit, and 10 to 60 mol% of monomer unit represented by the formula (A). A particularly preferable embodiment is represented by a fluorovinyl monomer (1) unit of 35 to 65 mol%, a monomer (2) unit of 25 to 55 mol%, and a formula (A) of 20 to 35 mol%. Is to include the monomer unit.
As the fluorine-containing vinyl monomer (1), TFE or HFP is preferable, and TFE is more preferable. As the monomer (2), ^{isobolonyl acrylate in which X B} of the general formula (2) is H is preferable. As the monomer (3), vinyl benzoate is preferable.

As one of the particularly preferable embodiments of the fluorine-containing polymer of the present disclosure, 10 to 90 mol% of fluorine-containing vinyl monomer (1) unit, 10 to 80 mol% of monomer (2) unit, 0 to 70 mol%. Monomer (3) units, including 0-80 mol% of monomer (4) units. More preferred embodiments are 20-80 mol% fluorovinyl monomer (1) units, 5-70 mol% monomer (2) units, 1-60 mol% monomer (3) units, 0.1-30 mol. % Is contained, and a more preferred embodiment is 30 to 70 mol% of fluorovinyl monomer (1) units, 10 to 60 mol% of monomer (2) units, 5 to 50 mol%. (3) units, 10 to 60 mol% of monomer (4) units, and a particularly preferred embodiment is 35 to 65 mol% of fluorovinyl monomer (1) units, 15 to 40 mol%. It comprises 10 to 40 mol% of monomer (3) units and 1 to 10 mol% of monomer (4) units.
Since the fluoropolymer of the present disclosure has such an embodiment, it is particularly suitable as a material for powder coating materials.
As the fluorine-containing vinyl monomer (1), TFE or HFP is preferable, and TFE is more preferable. As the monomer (2), ^{isobolonyl acrylate in which X B} of the general formula (2) is H is preferable. As the monomer (3), vinyl benzoate is preferable.

The fluoropolymer of the present disclosure can be produced by setting the composition of the fluoropolymer as described above.

The fluoropolymer of the present disclosure can be produced by a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, or a mass polymerization method, and among them, those obtained by the solution polymerization method are preferable.

The fluoropolymer of the present disclosure is preferably produced by polymerizing a monomer giving the above units by a solution polymerization method using an organic solvent, a polymerization initiator, a chain transfer agent, or the like. The polymerization temperature is usually 0 to 150 ° C, preferably 5 to 95 ° C. The polymerization pressure is usually 0.1 to 10 MPaG (1 to 100 kgf / cm ² G).

Examples of the organic solvent include esters such as methyl acetate, ethyl acetate, propyl acetate, n-butyl acetate and tert-butyl acetate; ketones such as acetone, methyl ethyl ketone and cyclohexanone; hexane, cyclohexane, octane, nonane, decane and undecane. , Dodecane, aliphatic hydrocarbons such as mineral spirit; aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene, solvent naphtha; methanol, ethanol, tert-butanol, iso-propanol, ethylene glycol monoalkyl ether, etc. Alcohols; cyclic ethers such as tetrahydrofuran, tetrahydropyran, dioxane; dimethylsulfoxide and the like, or mixtures thereof and the like.

Examples of the polymerization initiator include persulfates such as ammonium persulfate and potassium persulfate (and, if necessary, reducing agents such as sodium hydrogen sulfite, sodium pyrosulfate, cobalt naphthenate, and dimethylaniline); oxidizing agents. Redox initiators consisting of (eg ammonium peroxide, potassium peroxide, etc.), reducing agents (eg sodium sulfite, etc.) and transition metal salts (eg iron sulfate, etc.); diacyl peroxides such as acetyl peroxide, benzoyl peroxide, etc. Dialkoxycarbonyl peroxides such as isopropoxycarbonyl peroxide and tert-butoxycarbonyl peroxide; ketone peroxides such as methylethylketone peroxide and cyclohexanone peroxide; hydrogen peroxide, tert-butylhydroperoxide, cumenehydroper Hydroperoxides such as oxides; Dialkyl peroxides such as di-tert-butyl peroxide and dicumyl peroxide; Alkyl peroxyesters such as tert-butylperoxyacetate and tert-butylperoxypivalate; 2 , 2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylvaleronitrile), 2,2'-azobis (2-) Cyclopropylpropionitrile), dimethyl 2,2'-azobisisobutyrate, 2,2'-azobis [2- (hydroxymethyl) propionitrile], azo such as 4,4'-azobis (4-cyanopentenoic acid) System compounds can be used.
The chain transfer agent is, for example, alcohols, preferably alcohols having 1 to 10 carbon atoms, and more preferably monohydric alcohols having 1 to 10 carbon atoms. Specifically, methanol, ethanol, propanol, isopropanol, n-butanol, t-butanol, 2-methylpropanol, cyclohexanol, methylcyclohexanol, cyclopentanol, methylcyclopentanol, and dimethylcyclopentanol can be used. Of these, methanol, isopropanol, t-butanol, cyclohexanol, methylcyclohexanol, cyclopentanol, methylcyclopentanol and the like are preferable, and methanol and isopropanol are particularly preferable.

Since the fluoropolymer of the present disclosure has excellent heat resistance, it can be used for a resin layer of a metal-clad laminate, a powder coating material, or the like.

The present disclosure also relates to curable compositions comprising the fluoropolymers of the present disclosure. That is, the curable composition of the present disclosure contains the above-mentioned fluoropolymer, and the above-mentioned fluoropolymer has a TFE (1) unit and the following general formula (2):

(In the formula, X ^B is H or CH ₃ ), and includes a monomer (2) unit based on the monomer (2).
Although the powder coating material is required to have heat resistance, the fluoropolymer proposed for the conventional powder coating material cannot be said to have sufficient heat resistance.
The curable composition of the present disclosure can obtain a cured product having excellent heat resistance by containing the above-mentioned fluoropolymer. It also has excellent dispersibility, moisture resistance, flame retardancy, and adhesiveness.

The fluoropolymer in the curable composition of the present disclosure is the same as the fluoropolymer of the present disclosure. Therefore, all the preferred embodiments described in the fluoropolymers of the present disclosure can be adopted.

The curable composition of the present disclosure preferably further contains a resin (B) different from the fluoropolymer of the present disclosure. The resin (B) may be different from the fluoropolymer of the present disclosure, and examples thereof include non-fluororesins such as acrylic resins, polyester resins, polyurethane resins, epoxy resins, and silicone resins. From the viewpoint of compatibility with the fluoropolymer, at least one selected from the group consisting of acrylic resin, polyester resin and epoxy resin is more preferable, and at least one selected from the group consisting of polyester resin and epoxy resin is particularly preferable. Preferably, an epoxy resin is particularly preferred.
The number average molecular weight of the resin (B) is preferably 100,000 or less from the viewpoint of low melt viscosity.
The mass average molecular weight of the resin (B) is preferably 1,000 to 200,000 from the viewpoint of low melt viscosity.
The number average molecular weight and the mass average molecular weight of the resin (B) are values measured in accordance with JIS K 7252.

<Acrylic resin>
Acrylic resin is a polymer having (meth) acrylate units. The acrylic resin may have a reactive group such as a carboxy group, a hydroxyl group, or a sulfo group. The acrylic resin having a reactive group is excellent in dispersibility when the curable composition of the present disclosure contains a pigment such as a titanium oxide pigment.
The glass transition temperature of the acrylic resin is preferably 30 to 60 ° C. When the glass transition temperature is 30 ° C. or higher, the coating film is less likely to block. When the glass transition temperature of the acrylic resin is 60 ° C. or lower, the appearance and surface smoothness of the coating film are further excellent. The number average molecular weight of the acrylic resin is preferably 5,000 to 100,000, particularly preferably 10,000 to 100,000. When the number average molecular weight of the acrylic resin is at least the lower limit of the above range, the coating film is unlikely to block. When the number average molecular weight of the acrylic resin is not more than the upper limit of the above range, the surface smoothness of the coating film is further excellent.
The mass average molecular weight of the acrylic resin is preferably 6000 to 150,000, more preferably 40,000 to 150,000, and particularly preferably 60,000 to 150,000. When the mass average molecular weight of the acrylic resin is at least the lower limit of the above range, the coating film is less likely to block, and when the mass average molecular weight of the acrylic resin is at least the upper limit of the above range, the surface smoothness of the coating film is further excellent. ..
When the acrylic resin has a carboxy group, the acid value of the acrylic resin is preferably 150 to 400 mgKOH / g. When the acid value of the acrylic resin is at least the lower limit of the above range, when the curable composition of the present disclosure contains a pigment such as a titanium oxide pigment, there is an effect of improving the dispersibility thereof. When the acid value of the acrylic resin is not more than the upper limit of the above range, the coating film has excellent moisture resistance. When the acrylic resin has a hydroxyl group, the hydroxyl value of the acrylic resin is preferably 1 to 250 mgKOH / g from the viewpoint of adhesion to the substrate.

<Polyester resin>
Examples of the polyester resin include those having a polyvalent carboxylic acid unit and a polyhydric alcohol unit, and optionally having a unit other than these two units (for example, a hydroxycarboxylic acid unit).
As the polyester resin, a linear polymer or a branched polymer having a small number of branches is preferable, and a linear polymer is particularly preferable. Since a branched polymer having many branches tends to have a high softening point and a melting temperature, when the polyester resin is a branched polymer, the softening point is preferably 200 ° C. or lower. As the polyester resin, a polyester resin which is solid at room temperature and has a softening point of 100 to 150 ° C. is preferable.
The number average molecular weight of the polyester resin is preferably 5000 or less. The mass average molecular weight of the polyester resin is preferably 2000 to 20000, and particularly preferably 2000 to 10000. The polyester resin preferably has a number average molecular weight of 5000 or less and a mass average molecular weight of 2000 to 20000, and a polyester resin having a number average molecular weight of 5000 or less and a mass average molecular weight of 2000 to 10000. Especially preferable.
The polyester resin may have a reactive group capable of reacting with a curing agent described later. At least a part of the terminal unit of the polymer chain of the polyester resin is preferably a monovalent polyvalent carboxylic acid unit or a monovalent polyhydric alcohol unit, and in the former case, the free carboxy contained in the unit. When the group is the latter, the free hydroxyl group of the unit functions as a reactive group. The unit having a reactive group may be a unit other than the terminal unit. For example, since a divalent polyhydric alcohol unit derived from a polyhydric alcohol having 3 or more hydroxyl groups is a unit having a free hydroxyl group, the polyester resin has a divalent or higher unit having the reactive group. You may be doing it.
As the reactive group in the polyester resin, a hydroxyl group is preferable from the viewpoint of excellent water resistance, alkali resistance and acid resistance of the coating film. The polyester resin usually has a hydroxyl group and a carboxy group, and the polyester resin is preferably a polyester resin having a hydroxyl group.
The hydroxyl value of the polyester resin is preferably 20 to 100 mgKOH / g, particularly preferably 20 to 80 mgKOH / g. The acid value of the polyester resin is preferably 1 to 80 mgKOH / g, particularly preferably 3 to 50 mgKOH / g. The hydroxyl value and acid value of the polyester resin are values measured in accordance with JIS K 0070: 1992.
As the polyester resin, a polyester resin having an aromatic polyvalent carboxylic acid unit having 8 to 15 carbon atoms and a polyhydric alcohol unit having 2 to 10 carbon atoms is preferable from the viewpoint that the melt viscosity of the molten film can be lowered.
Further, the polyester resin may be, for example, the polyester resin described in International Publication No. 2014/002964.

<Epoxy resin>
Examples of the epoxy resin include phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthol novolac type epoxy resin, bisphenol novolac type epoxy resin, biphenol novolac type epoxy resin, bisphenol type epoxy resin, biphenyl type epoxy resin, and triphenol methane. Examples thereof include a type epoxy resin, a tetraphenol ethane type epoxy resin, a dicyclopentadiene-phenol addition reaction type epoxy resin, a phenol aralkyl type epoxy resin, and a naphthol aralkyl type epoxy resin.
More specifically, Epicoat 828 (manufactured by Shell Chemical Co., Ltd.), an epibis-type compound based on bisphenol A, etc., alkyl-modified EPICLON800, EPICLON4050, EPICLON1121N (manufactured by DIC), Shodyne (manufactured by Showa Denko), Araldite CY. Glycidyl ester compounds such as -183 (manufactured by Ciba Geigy), Novolac type Epicoat 154 (manufactured by Shell Chemical Co., Ltd.), DEN431, DEN438 (manufactured by Dow Chemical Co., Ltd.), Cresol Novolac type ECN1280, ECN1235 (manufactured by Ciba Geigy), urethane Modified EPU-6, EPU-10 (manufactured by Jiryuuka Kogyo Co., Ltd.) and the like can be mentioned.

The weight average molecular weight of the epoxy resin is preferably 100 to 1000000. When the weight average molecular weight of the epoxy resin is in such a range, the resin layer and the metal foil can be firmly adhered to each other. The weight average molecular weight of the epoxy resin is more preferably 1000 to 100,000.
The weight average molecular weight of the epoxy resin can be measured, for example, by gel permeation chromatography (GPC).

The epoxy resin preferably has an epoxy equivalent of 50 to 5000 g / eg. It is more preferably 50 to 1000 g / eg, and even more preferably 50 to 500 g / eg.
The epoxy equivalent is determined in accordance with JIS7236.

From the viewpoint of weather resistance, the curable composition of the present disclosure preferably contains 1 part by mass or more of the resin (B) with respect to 100 parts by mass of the fluoropolymer, and more preferably 50 parts by mass or more. It is preferably contained in an amount of 80 parts by mass or more, more preferably 80 parts by mass or more. Further, the resin (B) is preferably contained in an amount of 1000 parts by mass or less, more preferably 500 parts by mass or less, and further preferably 300 parts by mass or less with respect to 100 parts by mass of the fluoropolymer. It is particularly preferable to contain 200 parts by mass or less.

The curable composition of the present disclosure preferably further contains a curing agent. When at least one of the fluoropolymer and the resin (B) of the present disclosure has a reactive group (hydroxyl group, carboxy group, etc.), the curing agent reacts with the reactive group to form the fluoropolymer of the present disclosure. It is a compound that cures the resin (B) by cross-linking or increasing the molecular weight. The curing agent preferably has two or more reactive groups capable of reacting with the reactive groups of the fluoropolymer and the resin (B) of the present disclosure. Since it is not preferable that the reactive group of the curing agent easily reacts with the reactive group of the fluoropolymer and the resin (B) of the present disclosure at room temperature, the powder coating material made of the above-mentioned curable composition is heated and melted. It is preferably a reactive group that can react at the time.

As the curing agent, a known compound can be used, for example, a blocked isocyanate-based curing agent, an amine-based curing agent (a melamine resin, a guanamine resin, or a sulfoamide resin having an amino group to which a hydroxymethyl group or an alkoxymethyl group is bonded). , Urea resin, aniline resin, etc.), β-hydroxyalkylamide-based curing agent, epoxy-based curing agent (triglycidyl isocyanurate, etc.).

It is also preferable to use a blocked isocyanate-based curing agent from the viewpoints of excellent adhesion to the base material, processability of the product after coating, water resistance of the coating film, and the like. The blocked isocyanate-based curing agent is preferably solid at room temperature. To give an example of the isocyanate, a polyisocyanate obtained by reacting an aliphatic, aromatic, and aromatic aliphatic diisocyanate with a low molecular weight compound having active hydrogen is reacted with a blocking agent and masked. It may be manufactured. Further, examples of the diisocyanate used here include tolylene diisocyanate, 4,4'-diphenylmethane isocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), methylcyclohexanediisocyanate, and bis (isocyanate). Methyl) cyclohexane, isophorone diisocyanate, dimerate diisocyanate, lysine diisocyanate and the like.
Examples of low-molecular-weight compounds having active hydrogen include water, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, ethanolamine, diethanolamine, hexamethylenediamine, and the like, as well as isocyanurate. , Uretidine, low molecular weight polyester containing hydroxyl group, polycaprolactone and the like. Specific examples of the blocking agent include alcohols such as methanol, ethanol and benzyl alcohol, phenols such as phenol and crezone, lactams such as caprolactam and butyrolactam, and oximes such as cyclohexanone, oxime and methylethylketooxime. ..
The softening temperature of these blocked isocyanate-based curing agents is preferably 10 ° C to 120 ° C, and particularly preferably 40 to 100 ° C. If the softening temperature is less than 10 ° C., the curable composition is cured in an environment of about room temperature, or granular lumps are formed, which is not preferable. Further, if the temperature exceeds 120 ° C., when the curable composition is melt-kneaded and produced, it becomes difficult to uniformly disperse the blocked isocyanate-based curing agent in the composition, and the smoothness and coating film of the obtained coating film are obtained. Performance such as strength and moisture resistance may be impaired. These blocked isocyanate-based curing agents preferably have an isocyanate group of 0.05 to 1.5 equivalents, more preferably 0.8 to 1.2 equivalents, with respect to the hydroxyl groups in the resin component. If the isocyanate group is less than 0.05 equivalent, the degree of curing of the coating film is insufficient, and the coating film performance such as adhesion, coating film hardness, and chemical resistance may be lowered. If it exceeds 1.5 equivalent, the coating film is applied. The film may become brittle, or the heat resistance, chemical resistance, moisture resistance, etc. may be deteriorated due to the influence of the excess isocyanate compound. Moreover, since the blocked isocyanate itself is expensive, it is disadvantageous in terms of cost.

As the curing agent, a primid curing type curing agent or a triglycidyl isocyanurate (TGIC) curing type curing agent is preferable because the by-product is only water or no by-product is generated.

Examples of the primid-curing type curing agent include β-hydroxyalkylamide.

Examples of the TGIC curing type curing agent include TGIC and the like.

The content of the curing agent is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, and 3 parts by mass or more with respect to 100 parts by mass of the fluoropolymer of the present disclosure. It is more preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and further preferably 5 parts by mass or less.

The curable composition of the present disclosure further preferably contains a curing catalyst. The curing catalyst accelerates the curing reaction and imparts good chemical and physical performance to the coating film. When a blocked isocyanate-based curing agent is used, a tin catalyst (tin octylate, tributyltin laurate, dibutyltin dilaurate, etc.) is preferable as the curing catalyst. When a primid curing type curing agent is used, the curing catalyst is preferably an amine compound, an imidazole compound, a cationic polymerization catalyst or the like. When a triglycidyl isocyanurate (TGIC) curing agent is used, the curing catalyst is preferably an amine compound, an imidazole compound, a cationic polymerization catalyst or the like.
As the curing catalyst, one type may be used alone, or two or more types may be used in combination.

The curable composition of the present disclosure also preferably contains a curing accelerator. Examples of the curing accelerator include phosphorus compounds, tertiary amines, imidazole compounds, pyridine compounds, organic acid metal salts, Lewis acids, amine complex salts and the like. It is preferably a basic catalyst, and more specifically, at least one selected from the group consisting of alkali metal hydroxides, pyridines and imidazole compounds is more preferable. More preferably, it is at least one selected from the group consisting of a tertiary amine, an imidazole compound, a pyridine compound, and an amine complex salt, and even more preferably, at least one selected from the group consisting of an imidazole compound and a pyridine compound. It is one kind, and particularly preferably 4-dimethylaminopyridine and 2-ethyl-4-methylimidazole.
Each of these may be used alone, or two or more types may be used in combination.

When the curable composition of the present disclosure contains the above-mentioned curing accelerator, the total amount of the above-mentioned fluoropolymer and the resin (B) is 5% by mass with respect to 100% by mass of the solid content of the presently disclosed curable composition. The above is preferable, 50% by mass or more is more preferable, 70% by mass or more is further preferable, and 80% by mass or more is further more preferable.

The curable compositions of the present disclosure include UV absorbers, pigments, light stabilizers, matting agents, surfactants, leveling agents, surface conditioners, degassing agents, fillers, heat stabilizers, and more, as required. One or more of various additives such as a thickener, a dispersant, an antistatic agent, a rust preventive, a silane coupling agent, an antifouling agent, and a decontamination treatment agent may be contained as other components.
As the ultraviolet absorber, either an organic ultraviolet absorber or an inorganic ultraviolet absorber can be used.
As the ultraviolet absorber, one type may be used alone, or two or more types may be used in combination.
As the pigment, a pigment selected from the group consisting of bright pigments, rust preventive pigments, coloring pigments and extender pigments is preferable.
As the pigment, one type may be used alone, or two or more types may be used in combination.
The bright pigment is a highly light-reflecting pigment composed of flake-like particles, and examples thereof include flake-like metal particles, mica particles, and pearl particles. The surface of the flake-like particles may be coated with a coating material. Examples of the flake-shaped metal particles include flake-shaped aluminum particles, flake-shaped nickel particles, flake-shaped stainless particles, flake-shaped copper particles, flake-shaped bronze particles, flake-shaped gold particles, and flake-shaped silver particles.
As the bright pigment, flake-shaped aluminum particles, mica particles or pearl particles are preferable, and flake-shaped aluminum particles are particularly preferable.
The specific weight of the flake-like particles ^{is preferably 0.1 to 4.0 g / cm 3} , more preferably 0.3 to 2.0 g / cm ³ .
Further, the ultraviolet absorber and pigment may be, for example, the ultraviolet absorber and pigment described in International Publication No. 2014/002964.

One of the preferred embodiments of the curable composition of the present disclosure is a powder coating. Since the fluoropolymer of the present disclosure is excellent in chemical resistance in addition to heat resistance and weather resistance, the curable composition of the present disclosure can be suitably used for powder coating materials. The present disclosure also provides the use of the fluoropolymers in powder coatings.

When the curable composition of the present disclosure is a powder coating material, the curable composition of the present disclosure preferably contains the fluoropolymer, the resin (B), and the curing agent of the present disclosure.
The resin (B) is preferably contained in an amount of 1 part by mass or more, more preferably 50 parts by mass or more, and further preferably 80 parts by mass or more with respect to 100 parts by mass of the fluoropolymer of the present disclosure. Further, the resin (B) is preferably contained in an amount of 1000 parts by mass or less, more preferably 500 parts by mass or less, and further preferably 300 parts by mass or less with respect to 100 parts by mass of the fluoropolymer. It is particularly preferable to contain 200 parts by mass or less.
Further, the curing agent is preferably contained in an amount of 0.1 part by mass or more, more preferably 1 part by mass or more, and further preferably 3 parts by mass or more with respect to 100 parts by mass of the fluoropolymer of the present disclosure. It is preferable, and it is preferably contained in an amount of 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 10 parts by mass or less.
As the curing agent, a blocked isocyanate-based curing agent, a primid curing type curing agent, or a triglycidyl isocyanurate (TGIC) curing type curing agent is preferable.
When the curable composition of the present disclosure is a powder coating material, it is preferable that the curable composition of the present disclosure is substantially free of an organic solvent. Here, "substantially free" means that the amount of the organic solvent is 0.1% by mass or less with respect to the curable composition.

The present disclosure also provides a substrate and a coated article having a cured product layer formed from the curable composition which is the powder coating material on the substrate.
The base material is not particularly limited, and examples thereof include inorganic substances, organic substances, and organic-inorganic composite materials. Examples of the inorganic substance include concrete, natural stone, glass, metal (iron, stainless steel, aluminum, copper, brass, titanium, etc.). Examples of organic substances include plastics, rubbers, adhesives, and wood. Examples of the organic-inorganic composite material include fiber reinforced plastic, resin reinforced concrete, and fiber reinforced concrete.
The cured product layer can be obtained by coating a curable composition, which is a powder coating material, on a substrate and curing the coating material. The above-mentioned coating method and curing method are not particularly limited as conventionally known methods can be adopted.
The coated article of the present disclosure may consist only of a base material and the cured product layer, or may further include one or more layers.

Next, the present invention will be described with reference to examples, but the present invention is not limited to such examples. Hereinafter, the present invention will be described in more detail with reference to Examples.

The physical properties described in the present specification are measured by the following measuring methods.

(1) NMR analysis:
Measuring device: NMR measuring device: 1H-NMR measuring device manufactured by VARIAN Co., Ltd .: 400 MHz (tetramethylsilane = 0 ppm)

(2) Elemental analysis (measurement of fluorine content (mass%))
Measuring device: Automatic sample combustion device (AQF-100 manufactured by Mitsubishi Chemical Corporation) Ion chromatograph (ICS-1500 Ion Chromatography System manufactured by DIONEX) Built-in sample 3 mg

(3) Molecular weight measuring device: Showax GPC-104 manufactured by Showa Denko KK
Measurement conditions: Tetrahydrofuran is used as the eluent, and polystyrene with a known molecular weight is used as the standard sample of molecular weight.

(4) Glass transition temperature According to ASTM E1356-98, the glass transition temperature and the crystal melting point were determined by the midpoint method from heat absorption in the second run using a DSC measuring device manufactured by METTLER TORDO.
Measurement conditions Temperature rise rate; 20 ° C / min
Sample amount; 10 mg
Heat cycle; -50 ° C to 150 ° C, temperature rise, cooling, temperature rise

(5) Infrared spectrum measuring device: Perkin-Elmer FTIR spectrometer 1760X (manufactured by PerkinElmer)
For the measurement, a powdery or film-like sample was scanned 40 times and measured to obtain an infrared spectrum.

Example 1
Acetone (1050 g), isobonyl acrylate (IBAC) (60 g), vinyl benzoate (VBz) (87 g), and acrylic acid (AA) (13 g) were added to a stainless steel autoclave having a capacity of 3000 ml. 130g was charged. The temperature was raised to 70.0 ° C. with stirring, and 8 g of a peroxide-based polymerization initiator was charged to initiate polymerization. When the internal pressure of the reactor decreased from 1.0 MPaG to 0.4 MPaG, the reaction was stopped to obtain a solution containing the polymer. The obtained solution was concentrated and dried to obtain a fluoropolymer. The polymer was a powdery solid at room temperature.

As a result of NMR analysis, the obtained fluoropolymer had a composition of 34 mol% of tetrafluoroethylene, 22 mol% of isobonyl acrylate, 36 mol% of vinyl benzoate, and 8 mol% of acrylic acid. From the molecular weight analysis, the number average molecular weight (Mn) was 8000. The glass transition temperature (Tg) was 74 ° C. The result of elemental analysis was a fluorine content of 18.7% by mass. The acid value was 30 mgKOH / g.

Comparative Example 1
Butyl acetate 2500 g, neononanoic acid vinyl ester (NNVE) 584 g, vinyl benzoate (VBz) 77 g, 4-hydroxybutyl vinyl ether (HBVE) 527 g, and crotonic acid (CA) 7 g were put into a stainless steel autoclave having a capacity of 6000 ml, and nitrogen pressure was reduced. The substitution operation was carried out, and 658 g of tetrafluoroethylene (TFE) was charged. The temperature was raised to 60.0 ° C. with stirring, and 30 g of a peroxide-based polymerization initiator was charged to initiate polymerization. When the internal pressure of the reactor decreased from 1.0 MPaG to 0.4 MPaG, the reaction was stopped to obtain a solution containing the polymer. The obtained solution was concentrated and dried to obtain a fluoropolymer. The polymer was a viscous solid at room temperature and did not retain its powdery form.

As a result of NMR analysis, the obtained fluoropolymers were tetrafluoroethylene 45.0 mol%, neononanoic acid vinyl ester 33.3 mol%, vinyl benzoate 5.5 mol%, 4-hydroxybutyl vinyl ether 15. The composition was 3 mol% and 0.9 mol% crotonic acid. From the molecular weight analysis, the number average molecular weight (Mn) was 16000. The glass transition temperature (Tg) was 30 ° C. As a result of elemental analysis, the fluorine content was 27.0% by mass. The acid value was 3 mgKOH / g.

Stability evaluation 1 g of the resin obtained in the example was put into a blower dryer at 60 ° C. and heated for 12 hours. The case where the powdery form was maintained was evaluated as 〇. The case where the shape changes without maintaining the original shape is marked with x.

Evaluation of reactivity with curing agent Primid curing agent (Primid XL552: β-hydroxyalkylamide, crosslinkable hydroxyl value: 660 mgKOH / g) and the polymers obtained in Examples and Comparative Examples are mixed and mixed while grinding in a mortar. A curable composition was obtained. 2 g of this curable composition was taken, reacted in a blower dryer at 180 ° C. for 30 minutes, and then cooled to obtain a cured product. The mixing amount was calculated from the hydroxyl value of the primid curing agent and the acid value of the polymers obtained in Examples and Comparative Examples, and the mixture was mixed so that the reaction points were equivalent.
Next, the gel fraction was measured as an index of the reactivity of the cured product.
The cured product was removed and wrapped in a pre-weighted 400 mesh metal wire mesh. A cured product wrapped in 25 ml of acetone and a wire net was placed in a 50 ml sample tube, and the cured product was immersed in acetone for 12 hours. Then, the wire mesh was taken out and dried. The weight after drying was measured to calculate the weight of the dried and cured product after immersion in acetone. The gel fraction was calculated as the weight of the dry cured product after immersion in acetone / the weight of the cured product before immersion in acetone × 100.

Claims (19)

1. The polymerization unit based on the fluorine-containing vinyl monomer (1) and the following general formula (2):
   

   

   A fluoropolymer comprising a polymerization unit based on the monomer (2) represented by (where ^{X B} is H or CH _{3 in the formula) and having a glass transition temperature of 40 ° C. or higher.}
2. The fluoropolymer according to claim 1, wherein the polymerization unit based on the monomer (2) is 10 mol% or more based on the total polymerization units.
3. The fluoropolymer according to claim 1 or 2, wherein the polymerization unit based on the fluorovinyl monomer (1) is 10 mol% or more based on the total polymerization units.
4. The fluorovinyl monomer (1) is at least one selected from the group consisting of vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, hexafluoropropylene and perfluoro (alkyl vinyl ether). The fluoropolymer according to any one of claims 1 to 3.
5. The fluoropolymer according to any one of claims 1 to 4, further comprising a polymerization unit based on a monomer (3) which is at least one selected from the group consisting of a vinyl ester monomer and a vinyl ether monomer.
6. The monomer (3) has the following formula (A):
   _{CH 2 = CH-O-C} (= O) -R A (A)
   The fluorine-containing polymer according to claim 5, which is a monomer represented by (in the formula, ^RA is an alkyl group having 1 to 4 carbon atoms or a phenyl group which may have a substituent).
7. The fluoropolymer according to any one of claims 1 to 6, further comprising a polymerization unit based on the curable functional group-containing monomer (4).
8. The fluoropolymer according to claim 7, wherein the curable functional group-containing monomer (4) is a monomer containing a carboxyl group or a hydroxyl group.
9. The curable functional group-containing monomer (4) is at least one monomer selected from the group consisting of acrylic acid, crotonic acid, itaconic acid, citraconic acid, methacrylic acid, and hydroxybutyl vinyl ether. 8. The fluorine-containing polymer according to 8.
10. The fluoropolymer according to any one of claims 7 to 9, wherein the polymerization unit based on the curable functional group-containing monomer (4) is 1 mol% or more based on the total polymerization units.
11. The fluoropolymer according to any one of claims 1 to 10, wherein the fluoropolymer has a number average molecular weight of 1000 to 500,000.
12. A curable composition comprising the fluoropolymer according to any one of claims 1 to 11.
13. The curable composition according to claim 12, further comprising a curing agent.
14. The curable composition according to claim 13, wherein the curing agent is a primid-curing type or triglycidyl isocyanurate-curing type curing agent.
15. The curable composition according to any one of claims 12 to 14, further comprising a resin (B) different from the fluoropolymer.
16. The curable composition according to claim 15, which contains 1 to 1000 parts by mass of the resin (B) with respect to 100 parts by mass of the fluoropolymer.
17. The curable composition according to claim 15 or 16, wherein the resin (B) is at least one selected from the group consisting of an acrylic resin, a polyester resin, and an epoxy resin.
18. The curable composition according to any one of claims 12 to 17, further comprising a curing accelerator.
19. The curable composition according to any one of claims 12 to 18, which is a powder coating material.