Composition and crosslinked product

Abstract

Provided are a composition containing a fluorine-containing copolymer with which it is possible to obtain a crosslinked product excellent in heat resistance and low-temperature resistance, and a crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition. The composition contains a fluorine-containing copolymer, a peroxide, a compound C1 having two or more polymerizable unsaturated bonds in one molecule, and a compound C2 having two maleimide groups in one molecule.

Description

Compositions and crosslinked products

[0001] This invention relates to compositions and crosslinked products.

[0002] Crosslinked fluorine-containing copolymers exhibit excellent heat resistance, chemical resistance, oil resistance, and weather resistance, making them suitable for applications in harsh environments where crosslinked hydrocarbon copolymers cannot be used. For example, crosslinked fluorine-containing copolymers are used as components such as O-rings, gaskets, seals, and valves in automobiles, ships, aircraft, general machinery, chemical plants, industrial equipment, robot parts, and electronic component manufacturing equipment. In particular, due to their high heat resistance, crosslinked fluorine-containing copolymers are suitable for drilling components, furnace components, and semiconductor integrated circuit manufacturing equipment.

[0003] Methods for improving the heat resistance of crosslinked fluorine-containing copolymers include crosslinking using fluorine-containing aromatic compounds (for example, Patent Document 1).

[0004] International Publication No. 2015 / 020004

[0005] However, improvements are being made to obtain crosslinked fluorine-containing copolymers with higher heat resistance so that they can be used at even higher temperatures. In addition, depending on the application, crosslinked fluorine-containing copolymers may also require low-temperature resistance.

[0006] The object of the present invention is to provide a composition containing a fluorine-containing copolymer capable of producing a crosslinked product with excellent heat resistance and low-temperature resistance, and a crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition.

[0007] The present invention has the following aspects. [1] A composition containing a fluorine-containing copolymer, a peroxide, a compound C1 having two or more polymerizable unsaturated bonds in one molecule, and a compound C2 having two maleimide groups in one molecule. [2] The composition according to [1], wherein the content of the compound C1 with respect to 100 parts by mass of the fluorine-containing copolymer is 0.01 to 5 parts by mass. [3] The composition according to [1] or [2], wherein the content of the compound C2 with respect to 100 parts by mass of the fluorine-containing copolymer is 0.01 to 5 parts by mass. [4] The composition according to any one of [1] to [3], wherein the content of the compound C2 with respect to 100 parts by mass in total of the compound C1 and the compound C2 is 1 to 99 parts by mass. [5] The composition according to any one of [1] to [4], wherein the fluorine-containing copolymer is a fluorine-containing copolymer having units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether). [6] The composition according to any one of [1] to [5], wherein the compound C1 is a compound represented by the following formula C1. (CR ２１ R ２２ =CR ２３ ) ２ R ２４ Formula C1 In the formula C1, R ２１ , R ２２ , and R ２３ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ２４ is a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal of a perfluoroalkylene group having 1 to 10 carbon atoms or between carbon-carbon bonds. A plurality of R ２１ , a plurality of R ２２ , and a plurality of R ２３ may be the same as or different from each other. [7] The composition according to any one of [1] to [5], wherein the compound C1 is a compound having three allyl groups in one molecule. [8] The composition according to any one of [1] to [7], wherein the compound C2 is a compound represented by the following formula C2.

[0008] In formula C2, R is a divalent aromatic group, and at least one hydrogen atom in the divalent aromatic group may be substituted with a fluorine atom. [9] The composition according to [8], wherein compound C2 is N,N'-m-phenylenedimaleimide.

[10] A crosslinked product obtained by crosslinking the fluorine-containing copolymer in any of the compositions according to [1] to [9].

[0009] According to the present invention, it is possible to provide a composition containing a fluorine-containing copolymer that can be used to obtain a crosslinked product with excellent heat resistance and low-temperature resistance, and a crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition.

[0010] The following terms used in this specification are defined as follows: "Monomer" refers to a compound having polymerizable unsaturated bonds. Examples of polymerizable unsaturated bonds include double bonds and triple bonds between carbon atoms. "Monomer-based unit" refers to an atomic group directly formed by the polymerization of monomers, and an atomic group obtained by chemically transforming a part of said atomic group. A monomer-based unit is also referred to as a "monomer unit."

[0011] ≪Composition≫ The composition of this embodiment contains a fluorine-containing copolymer, a peroxide, compound C1 having two or more polymerizable unsaturated bonds in one molecule, and compound C2 having two maleimide groups in one molecule.

[0012] <Fluorine-containing copolymers> Fluorine-containing copolymers are copolymers that contain units based on monomers containing fluorine atoms, and copolymers having rubber elasticity are preferred. The fluorine atoms may be bonded to carbon atoms constituting the main chain, or they may be bonded to carbon atoms constituting the side chains.

[0013] The fluorine atom content relative to the total mass of the fluorine-containing copolymer is preferably 40 to 75% by mass, more preferably 45 to 75% by mass, and even more preferably 50 to 75% by mass. When the fluorine atom content relative to the total mass of the fluorine-containing copolymer is within the above range, it is easy to obtain a crosslinked product with excellent mechanical properties, chemical resistance, and heat resistance.

[0014] Fluorine-containing copolymers include, specifically, copolymers having units based on tetrafluoroethylene (hereinafter referred to as TFE) and units based on perfluoro(alkyl vinyl ether) (hereinafter referred to as PAVE) (hereinafter referred to as Copolymer 1), copolymers having units based on TFE and units based on propylene (hereinafter referred to as P) (hereinafter referred to as Copolymer 2), and copolymers having units based on hexafluoropropylene (hereinafter referred to as HFP) and units based on vinylidene fluoride (hereinafter referred to as VdF) (hereinafter referred to as Copolymer 3). Copolymer 1 is particularly preferred in that it has even better chemical resistance and heat resistance. Hereinafter, units based on compounds (monomers) will also be referred to as "compound units."

[0015] (Copolymer 1) Copolymer 1 is a copolymer having TFE units and PAVE units. The PAVE units in copolymer 1 are preferably units based on a compound represented by formula 1 (hereinafter referred to as compound 1; the same applies to other compounds). CF ２ =CF-O-R ｆ１ Equation 1 In the above Equation 1, R ｆ１ These are perfluoroalkyl groups having 1 to 10 carbon atoms.

[0016] R ｆ１ In this, the perfluoroalkyl group may be linear or branched. ｆ１ The number of carbon atoms is preferably 1 to 5, and more preferably 1 to 3, from the viewpoint of improving the productivity of copolymer 1.

[0017] Preferred specific examples of compound 1 include perfluoro(methyl vinyl ether) (hereinafter referred to as PMVE), perfluoro(ethyl vinyl ether) (hereinafter referred to as PEVE), perfluoro(propyl vinyl ether) (hereinafter referred to as PPVE), and perfluoro(butyl vinyl ether). Among the above, PMVE, PEVE, and PPVE are preferred as compound 1 from the viewpoint of improving the productivity of copolymer 1.

[0018] Copolymer 1 may contain units other than TFE units and PAVE units. Examples of units other than TFE units and PAVE units contained in copolymer 1 include perfluorooxaalkyl vinyl ether (hereinafter referred to as POAVE) units, compounds having two or more polymerizable unsaturated bonds (hereinafter referred to as DVE) units, and compound units having a fluorine atom and a nitrile group. It is preferable that copolymer 1 contains one or more selected from the group consisting of POAVE units, DVE units, and compound units having a fluorine atom and a nitrile group.

[0019] As the POAVE unit, a unit based on compound 2 represented by the following formula 2 is preferred. When compound 2 units are present, the rubber properties at low temperatures (hereinafter referred to as low-temperature properties) of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition are excellent. CF ２ =CF - (OCF ２ CF ２ CF ２ ) ｐ２ - (OCF ２ CF ２ ) ｎ２ - (OCF ２ ) ｍ２ -OR ｆ２ Equation 2 In Equation 2 above, R ｆ２ A is a perfluoroalkyl group having 1 to 4 carbon atoms, where p2 is an integer from 0 to 3, n2 is an integer from 0 to 3, m2 is an integer from 0 to 4, and p2 + n2 + m2 is an integer from 1 to 7.

[0020] R ｆ２ In this, the perfluoroalkyl group may be linear or branched. ｆ２ When the number of carbon atoms, p2, n2, and m2 are within the above range, the productivity of copolymer 1 is improved, and the low-temperature properties of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition are excellent.

[0021] Examples of compound 2 include the following compound: CF ２ = CF - OCF ２ CF ２ -OCF ２ -OCF ２ -OCF ２ -OCF ２ -OCF３ (Hereafter referred to as C9PEVE), CF ２ = CF - OCF ２ CF ２ -OCF ２ -OCF ２ -OCF ３ (Hereafter referred to as C7PEVE.) CF ２ = CF - OCF ２ CF ２ -OCF ２ CF ２ -OCF ２ CF ３ (Hereinafter referred to as EEAVE), CF ２ = CF - OCF ２ CF ２ -OCF ２ CF ２ -OCF ２ CF ２ -OCF ２ CF ３ (Hereafter referred to as EEEAVE), CF ２ = CF - OCF ２ -OCF ３ CF ２ = CF - OCF ２ -OCF ２ CF ３ CF ２ =CF - O(CF ２ CF (CF ３ )O) ２ CF ２ CF ２ CF ３ CF ２ = CF - OCF ２ -OCF ２ -OCF ３ etc.

[0022] As compound 2, C9PEVE, C7PEVE, EEAVE, and EEEAVE are even more preferred because they improve the productivity of copolymer 1 and the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition exhibits excellent low-temperature properties. These compounds can be produced using the corresponding alcohol as a raw material by the method described in International Publication No. 00 / 56694.

[0023] As the polymerizable unsaturated bond of DVE, examples include double bonds and triple bonds between carbon atoms, and a double bond is preferred. The number of polymerizable unsaturated bonds is preferably 2 to 6, more preferably 2 or 3, and particularly preferably 2. As DVE, those containing a fluorine atom are preferred. When the copolymer 1 has a DVE unit containing a fluorine atom, the rubber physical properties of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition are likely to be maintained, and the low-temperature characteristics are excellent. The DVE having a fluorine atom is more preferably a perfluorinated compound.

[0024] As the DVE which is a perfluorinated compound, from the viewpoint of further excellent low-temperature characteristics while maintaining the rubber physical properties of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition, the compound 3 represented by the following formula 3 is preferred. CF ２ =CF−OR ｆ３ OCF=CF ２ Formula 3 In the above formula 3, R ｆ３ is a perfluoroalkylene group having 1 to 25 carbon atoms, or a group having one or more etheric oxygen atoms between carbon atoms of a perfluoroalkylene group having 2 to 25 carbon atoms.

[0025] For R ｆ３ , the perfluoroalkylene group may be linear or a branched chain having a side chain. From the viewpoint of further excellent low-temperature characteristics while maintaining the rubber physical properties of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition, the carbon number of R ｆ３ is preferably 3 or 4.

[0026] Examples of the compound 3 include the following compounds. CF ２ =CFO(CF ２ ) ２ OCF=CF ２ , CF ２ =CFO(CF ２ ) ３ OCF=CF ２ (hereinafter referred to as C3DVE), CF ２ =CFO(CF ２ ) ４ OCF=CF ２ (hereinafter referred to as C4DVE), CF ２ =CFO(CF２ ) ６ OCF = CF ２ CF ２ = CFO (CF ２ ) ８ OCF = CF ２ CF ２ = CFO (CF ２ ) ２ OCF (CF ３ ) CF ２ OCF = CF ２ CF ２ = CFO (CF ２ ) ２ O(CF(CF ３ ) CF ２ O) ２ CF = CF ２ CF ２ = CFOCF ２ O(CF) ２ CF ２ O) ２ CF = CF ２ CF ２ = CFO (CF ２ O) ３ (CF(CF ３ ) CF ２ O) ２ CF = CF ２ CF ２ = CFOCF ２ CF (CF ３ ) O (CF ２ ) ２ OCF (CF ３ ) CF ２ OCF = CF ２ CF ２ = CFOCF ２ CF ２ O(CF) ２ O) ２ CF ２ CF ２ OCF = CF ２ etc.

[0027] As compound 3, C3DVE and C4DVE are preferred because they maintain the rubber properties of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition while exhibiting even better low-temperature properties.

[0028] As a compound unit having a fluorine atom and a nitrile group, a unit based on compound 4 represented by the following formula 4 is preferred. CR ４１ R ４２ =CR ４３ -R ４４ -CN Formula 4 In formula 4, R ４１ , R ４２ and R ４３ Each of these independently represents a hydrogen atom, a fluorine atom, or a methyl group. ４４ This represents a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of a perfluoroalkylene group having 1 to 10 carbon atoms.

[0029] R ４１ , R ４２ and R ４３ Each of these atoms is preferably independently a fluorine atom or a hydrogen atom, more preferably all are fluorine atoms or all are hydrogen atoms, and even more preferably all are fluorine atoms.

[0030] R ４４ The chain may be linear, branched, or cyclic, with linear or branched being preferred. ４４ The number of carbon atoms is preferably 2 or more, and more preferably 3 or more. Also, R ４４ The number of carbon atoms is preferably 8 or less, more preferably 7 or less, even more preferably 6 or less, and particularly preferably 5 or less.

[0031] R ４４ It is preferable that the group has an etheric oxygen atom at the terminal end of a perfluoroalkylene group having 1 to 10 carbon atoms or between carbon-carbon bonds. ４４ The number of etheric oxygen atoms in is preferably 1 to 3, and more preferably 1 or 2. ４４ The etheric oxygen atom in R ４４ It is preferable that it be located at the end of CR. ４１ R ４２ =CR ４３ - is connected to R ４４ The atom inside is an etheric oxygen atom, and -CN is bonded to R ４４ It is preferable that the atoms inside are carbon atoms.

[0032] Compound 4 is CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CN (hereinafter also referred to as "8CNVE"), CF ２ = CFO (CF ２ ) ５ CN (hereinafter also referred to as "MV5CN"), CF ２ = CFOCF ２ CF ２ CF ２ OCF (CF ３ ) CN and CF ２ = CFO (CF ２ ) ３ CN is one example, and 8CNVE or MV5CN is preferred because they offer superior release properties and heat resistance for crosslinked rubber articles.

[0033] Copolymer 1 is preferably further enriched with iodine atoms for superior crosslinking reactivity. The iodine atoms are preferably bonded to the ends of the polymer chains of copolymer 1. The term "ends of the polymer chains" includes both the ends of the main chain and the ends of the side chains.

[0034] The iodine atom content of copolymer 1 relative to the total mass is preferably 0.01 to 1.5% by mass, and more preferably 0.01 to 1.0% by mass. When the iodine atom content is within the above range, the crosslinking reactivity of copolymer 1 is further improved.

[0035] Methods for introducing iodine atoms into copolymer 1 include copolymerizing monomers containing iodine atoms and using a chain transfer agent containing iodine atoms. The chain transfer agent containing iodine atoms will be described later.

[0036] Copolymer 1 may further have units based on other monomers, to the extent that it does not lose its effect. Examples of other monomers include monomers having fluorine atoms and halogen atoms other than fluorine atoms (bromotrifluoroethylene, iodotrifluoroethylene, etc.).

[0037] The content of TFE units relative to the total amount of all units constituting copolymer 1 is preferably 35 to 75 mol%, more preferably 40 to 75 mol%, and even more preferably 50 to 75 mol%.

[0038] The PAVE unit content relative to the total amount of all units constituting copolymer 1 is preferably 3 to 57 mol%, more preferably 5 to 50 mol%, and even more preferably 10 to 40 mol%.

[0039] The combined content of TFE units and PAVE units relative to the total amount of all units constituting copolymer 1 is preferably 99 mol% or more.

[0040] When copolymer 1 contains two units of compound, the content of two units of compound relative to the total number of units constituting copolymer 1 is preferably 3 to 57 mol%, more preferably 5 to 40 mol%, and even more preferably 8 to 30 mol%.

[0041] When copolymer 1 contains DVE-based units containing fluorine atoms, the content of DVE-based units containing fluorine atoms relative to the total amount of all units constituting copolymer 1 is preferably 0.01 to 1 mol%, more preferably 0.05 to 0.5 mol%, and even more preferably 0.05 to 0.3 mol%.

[0042] When copolymer 1 contains compound units having a fluorine atom and a nitrile group, the content of compound units having a fluorine atom and a nitrile group relative to the total amount of all units constituting copolymer 1 is preferably 0.01 to 1 mol%, more preferably 0.05 to 0.5 mol%, and even more preferably 0.05 to 0.4 mol%.

[0043] The content of units based on other monomers relative to the total amount of all units constituting copolymer 1 is preferably 0 to 5 mol%, more preferably 0 to 3 mol%, and even more preferably 0 to 2 mol%.

[0044] When the content of TFE units, PAVE units, compound 2 units, DVE units containing fluorine atoms, compound units having fluorine atoms and nitrile groups, and units based on other monomers in copolymer 1 is within the above range, the low-temperature properties and alkali resistance of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition are further improved while maintaining the rubber properties.

[0045] Copolymer 1 can be produced by polymerizing monomer component 1. Monomer component 1 refers to the monomer composition that constitutes copolymer 1. Radical polymerization is preferred as the method for polymerizing monomer component 1. Examples of radical polymerization initiators include radical polymerization initiators, heat, and ionizing radiation. Among these, radical polymerization initiators are preferred because they offer excellent productivity in producing monomer component 1.

[0046] The radical polymerization initiator used in the production of copolymer 1 is not particularly limited. As the radical polymerization initiator used in emulsion polymerization described later, a water-soluble initiator is preferred. Examples of water-soluble initiators include ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide, disuccinate peroxide, diglutarate peroxide, tert-butyl hydroxyperoxide, and azobisisobutylamidine dihydrochloride. Furthermore, examples include redox initiators consisting of a combination of at least one compound selected from the group consisting of ammonium persulfate, sodium persulfate, potassium persulfate, and hydrogen peroxide and a reducing agent (sodium bisulfite, sodium thiosulfate, etc.), and initiators in which a small amount of iron, ferrous salt, silver sulfate, etc. are further present in the redox initiator.

[0047] The amount of radical polymerization initiator is preferably 0.0001 to 5 parts by mass, and more preferably 0.001 to 2 parts by mass, per 100 parts by mass of monomer component 1. When using a radical polymerization initiator, it is preferable to polymerize monomer component 1 in the presence of a chain transfer agent.

[0048] Examples of chain transfer agents used in polymerization include alcohols (methanol, ethanol, etc.), chlorofluorohydrocarbons (1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1-fluoroethane, etc.), hydrocarbons (pentane, hexane, cyclohexane, etc.), compound 5 represented by formula 5 below, compound 6 represented by formula 6 below, mercaptans (tert-dodecylmercaptan, n-octadecylmercaptan, etc.), etc. ｆ５ I ２ Formula 5 R ｆ６IBr Formula 6 In the above formulas 5 and 6, R ｆ５ and R ｆ６ This is a polyfluoroalkylene group having 1 to 16 carbon atoms.

[0049] R ｆ５ and R ｆ６ In this, the polyfluoroalkylene group may be linear or branched. ｆ５ and R ｆ６ A perfluoroalkylene group is preferred as the material.

[0050] Examples of compound 5 include 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 1,8-diiodoperfluoroctan. Examples of compound 6 include 1-iodo-4-bromoperfluorobutane, 1-iodo-6-bromoperfluorohexane, and 1-iodo-8-bromoperfluoroctan.

[0051] The amount of the chain transfer agent is appropriately set based on the chain transfer constant of the chain transfer agent. When compound 4 is used as the chain transfer agent, the amount of the chain transfer agent is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 2 parts by mass, per 100 parts by mass of monomer component 1.

[0052] Examples of polymerization methods for monomer component 1 include emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization. Among these, emulsion polymerization is preferred due to its superiority in adjusting molecular weight and copolymer composition, as well as productivity.

[0053] In emulsion polymerization, monomer component 1 is polymerized in an aqueous medium containing an emulsifier as needed. Examples of aqueous mediums include water and mixtures of water and water-soluble organic solvents. Examples of water-soluble organic solvents include tert-butanol, propylene glycol, dipropylene glycol, dipropylene glycol monomethyl ether, and tripropylene glycol. Tert-butanol and dipropylene glycol monomethyl ether are preferred because they do not reduce the polymerization rate of the monomer.

[0054] When the aqueous medium contains a water-soluble organic solvent, the dispersibility of the monomer and the dispersibility of monomer component 1 are further improved, and the productivity of monomer component 1 is also improved. The content of the water-soluble organic solvent is preferably 1 to 40 parts by mass, and more preferably 3 to 30 parts by mass, per 100 parts by mass of water.

[0055] Examples of emulsifiers include anionic emulsifiers, nonionic emulsifiers, and cationic emulsifiers, with anionic emulsifiers being preferred because they offer superior mechanical properties and chemical stability for latex.

[0056] Examples of anionic emulsifiers include hydrocarbon emulsifiers (such as sodium lauryl sulfate and sodium dodecylbenzenesulfonate) and fluorine-containing emulsifiers (such as ammonium perfluorooctanoate, sodium perfluorooctanoate, ammonium perfluorohexanoate, and compound 7 represented by formula 7 below). F(CF ２ ) ｐ７ O(CF(X)CF ２ O) ｑ７ CF(Y)COOA Formula 7 In Formula 7 above, X and Y are each independently a fluorine atom or a linear or branched perfluoroalkyl group having 1 to 3 carbon atoms, and A is a hydrogen atom, an alkali metal or NH ４ Therefore, p7 is an integer between 2 and 10, and q7 is an integer between 0 and 3.

[0057] The following compound is an example of compound 7: F(CF) ２ ) ３ O(CF(CF ３ ) CF ２ O) ２ CF (CF ３ ) COONH ４ F(CF) ２ ) ３ OCF ２ CF ２ OCF ２ COONH ４ F(CF) ２ ) ３ O(CF) ２ CF ２ O) ２ CF ２ COONH ４ F(CF)２ ) ４ OCF ２ CF ２ OCF ２ COONH ４ , F(CF ２ ) ４ O(CF ２ CF ２ O) ２ CF ２ COONH ４ , F(CF ２ ) ３ OCF ２ CF ２ OCF ２ COONa, F(CF ２ ) ３ O(CF ２ CF ２ O) ２ CF ２ COONa, F(CF ２ ) ４ OCF ２ CF ２ OCF ２ COONa, F(CF ２ ) ４ O(CF ２ CF ２ O) ２ CF ２ COONa, F(CF ２ ) ２ OCF ２ CF ２ OCF ２ COONH ４ , F(CF ２ ) ２ O(CF ２ CF ２ O) ２ CF ２ COONH ４ , F(CF ２ ) ２ OCF ２ CF ２ OCF ２ COONa, F(CF ２ ) ２ O(CF ２ CF ２ O) ２ CF ２ COONa, etc.

[0058] Examples of anionic emulsifiers include ammonium perfluorooctanoate, F(CF) ２ ) ２ OCF ２ CF ２ OCF ２ COONH ４ F(CF) ２ ) ４ OCF ２ CF ２ OCF ２ COONH ４ F(CF) ２ ) ３ OCF ２ CF ２ OCF ２ COONH ４ It is preferable.

[0059] The amount of emulsifier is preferably 0.01 to 15 parts by mass, and more preferably 0.1 to 10 parts by mass, per 100 parts by mass of aqueous medium.

[0060] Latex containing copolymer 1 is obtained by emulsion polymerization. Copolymer 1 can be separated from the latex by agglomeration. Examples of agglomeration methods include the addition of metal salts, the addition of inorganic acids (such as hydrochloric acid), mechanical shearing, and freeze-thawing.

[0061] The polymerization conditions for radical polymerization are appropriately selected depending on the monomer composition and the decomposition temperature of the radical polymerization initiator. The polymerization pressure is preferably 0.1 to 20 MPaG, more preferably 0.3 to 10 MPaG, and even more preferably 0.3 to 5 MPaG. The "G" attached to MPa indicates gauge pressure. The polymerization temperature is preferably 0 to 100°C, more preferably 10 to 90°C, and even more preferably 20 to 80°C. The polymerization time is preferably 1 to 72 hours, more preferably 1 to 24 hours, and even more preferably 1 to 12 hours.

[0062] The storage shear modulus G' of copolymer 1 is preferably 100 to 600 kPa, more preferably 200 to 500 kPa, and even more preferably 200 to 400 kPa. The storage shear modulus G' is a value measured according to ASTM D5289 and D6204 at a temperature of 100°C, an amplitude of 0.5 degrees, and a frequency of 50 vibrations / min. A larger storage shear modulus G' indicates a larger molecular weight of the polymer and a higher density of molecular chain entanglement. When the storage shear modulus G' of copolymer 1 is within the above range, the tensile strength and other mechanical properties of the crosslinked material are further improved.

[0063] (Copolymer 2) Copolymer 2 is a copolymer having TFE units and P units. Copolymer 2 may also contain other monomer units other than TFE and P. A copolymer having TFE units, P units and PAVE units is designated as Copolymer 2, not Copolymer 1. Examples of other monomer units include PAVE units, POAVE units, and DVE units.

[0064] Examples of PAVE units contained in copolymer 2 include units based on compound 8 represented by the following formula 8. CF ２ =CF-O-R ｆ８ Equation 8 In the above Equation 8, R ｆ８ R is a perfluoroalkyl group having 1 to 10 carbon atoms. ｆ８ The perfluoroalkyl group may be linear or branched. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 3. Examples of PAVE include PMVE, PEVE, PPVE, etc. PAVE may be used alone or in combination of two or more. Among these, PMVE is preferred.

[0065] Examples of POAVE units included in copolymer 2 include units based on compound 9 represented by the following formula 9. CF ２ =CF - (OCF ２ CF ２ CF ２ ) ｐ９ - (OCF ２ CF ２ ) ｎ９ - (OCF ２ )ｍ９ -OR ｆ９ Equation 9 In the above Equation 9, R ｆ９ A is a perfluoroalkyl group having 1 to 4 carbon atoms, p9 is an integer from 0 to 3, n9 is an integer from 0 to 3, m9 is an integer from 0 to 4, and p9 + n9 + m9 is an integer from 1 to 7.

[0066] R ｆ９ The perfluoroalkyl group may be linear or branched. Examples of compound 9 include perfluoro(3,6-dioxa-1-heptene), perfluoro(3,6-dioxa-1-octene), and perfluoro(5-methyl-3,6-dioxa-1-nonene). POAVE may be used alone or in combination of two or more types.

[0067] When DVE is copolymerized with TFE and P, a copolymer 2 having side chains is obtained. When copolymer 2 has DVE units, its mechanical properties such as crosslinking reactivity, tensile strength of the crosslinked material, and compression set characteristics at high temperatures are further improved.

[0068] The DVE units contained in copolymer 2 are preferably units based on at least one selected from the group consisting of compound 10 represented by formula 10, compound 11 represented by formula 11, and compound 12 represented by formula 12. １ R ２ =CR ３ -R ４ -CR ５ =CR ６ R ７ Formula 10 CR ８ R ９ =CR １０ -OCO-R １１ -COO-CR １２ =CR １３ R １４ Formula 11 CR １５ R １６ =CR １７ COOCH = CH ２ Equation 12 In the above equations 10 to 12, R １ , R ２ , R ３ , R ５ , R ６ , R ７ , R ８, R ９ , R １０ , R １２ , R １３ , R １４ , and R １７ Each of these is independently a hydrogen atom, a fluorine atom, or a methyl group, and R ４ and R １１ Each of these is independently an alkylene group having 1 to 10 carbon atoms, a group having an etheric oxygen atom between the carbon atoms of an alkylene group having 1 to 10 carbon atoms, a fluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom between the carbon atoms of a fluoroalkylene group having 1 to 10 carbon atoms, R １５ and R １６ Each of these is independently a hydrogen atom, a C1-C10 alkyl group, or a group having an etheric oxygen atom between the carbon atoms of a C1-C10 alkyl group.

[0069] Examples of compound 10 include compounds in which a group independently selected from a vinyl group, an allyl group, and a butenyl group is bonded to each of the ends of an alkylene group or fluoroalkylene group having 1 to 10 carbon atoms, with or without an etheric oxygen atom interposed therebetween. Examples of cases where an etheric oxygen atom is interposed include divinyl ethers, allyl vinyl ethers, butenyl vinyl ethers, fluoro(divinyl ethers), fluoro(allyl vinyl ethers), and fluoro(butenyl vinyl ethers).

[0070] Compound 10 is R because it enhances crosslinking reactivity and heat resistance. １ , R ２ , R ３ , R ５ , R ６ and R ７ Preferably, each of them is independently a fluorine atom or a hydrogen atom, R １ , R ２ , R ３ , R ５ , R ６ and R ７ It is more preferable that all of them are fluorine atoms.

[0071] R ４The alkylene group or fluoroalkylene group may be linear or branched. However, R ４ The alkylene group or fluoroalkylene group is preferably linear. ４ The number of carbon atoms is preferably 2 to 8, more preferably 3 to 7, even more preferably 3 to 6, and particularly preferably 3 to 5. ４ The number of etheric oxygen atoms in is preferably 0 to 3, and more preferably 1 to 2. ４ In these preferred embodiments, the mechanical properties of the bridged material, such as tensile strength and compression set characteristics at high temperatures, are further improved.

[0072] R ４ From the viewpoint of heat resistance and suppression of polymer discoloration, fluoroalkylene groups are preferred, and perfluoroalkylene groups are more preferred. Preferred specific examples of compound 10 include 1,4-butanediol divinyl ether, C3DVE, C4DVE, and CH ２ =CH(CF ２ ) ６ CH=CH ２ These are some examples.

[0073] Examples of compound 11 include divinyl esters, allyl vinyl esters, butenyl vinyl esters, etc. Compound 11 is R ８ , R ９ , R １０ , R １２ , R １３ and R １４ Preferably, it is a hydrogen atom.

[0074] R １１ For example, R ４ Similar groups are exemplified. The preferred range of carbon numbers is also similar. R １１ The number of etheric oxygen atoms in is preferably 0 to 1, and more preferably 0. A preferred specific example of compound 11 is divinyl adipate.

[0075] Compound 12 is R １６ and R １７It is preferable that the atom is a hydrogen atom. Preferred specific examples of compound 12 include vinyl crotate and vinyl methacrylate. Among these, vinyl crotate is more preferred as compound 12.

[0076] DVE may be used alone or in combination of two or more types. When copolymer 2 has DVE units, the content of DVE units relative to the total amount of all units constituting copolymer 2 is preferably 0.01 to 2 mol%, more preferably 0.01 to 1 mol%, and even more preferably 0.01 to 0.5 mol%. If the content of DVE units is above the lower limit of the above range, the crosslinking reactivity is excellent, and the mechanical properties of the crosslinked material, such as tensile strength and compression set at high temperatures, are further improved. If the content of DVE units is below the upper limit of the above range, the excellent physical properties of the crosslinked material can be maintained while reliably preventing or further reducing cracking when stress such as bending is applied at high temperatures.

[0077] Copolymer 2 preferably contains iodine atoms for even better crosslinking reactivity. The iodine atoms are preferably bonded to the ends of the polymer chains of copolymer 2. The term "ends of the polymer chains" includes both the ends of the main chain and the ends of the side chains.

[0078] The iodine atom content of copolymer 2 relative to the total mass is preferably 0.01 to 5.0% by mass, more preferably 0.05 to 2.0% by mass, and even more preferably 0.05 to 1.0% by mass. When the iodine atom content is within the above range, the mechanical properties of copolymer 2 are further improved.

[0079] Methods for introducing iodine atoms into copolymer 2 include copolymerizing monomers containing iodine atoms and introducing them using a chain transfer agent containing iodine atoms.

[0080] Examples of monomers containing an iodine atom include iodoethylene, 4-iodo-3,3,4,4-tetrafluoro-1-butene, 2-iodo-1,1,2,2-tetrafluoro-1-vinyloxyethane, 2-iodoethyl vinyl ether, allyl iodide, 1,1,2,3,3,3-hexafluoro-2-iodo-1-(perfluorovinyloxy)propane, 3,3,4,5,5,5-hexafluoro-4-iodopentene, iodotrifluoroethylene, and 2-iodoperfluoro(ethyl vinyl ether). Chain transfer agents containing an iodine atom will be discussed later.

[0081] Copolymer 2 may further have units based on other monomers, to the extent that it does not lose its effect. The other monomers are not particularly limited as long as they are compounds copolymerizable with TFE and P. Specifically, HFP, VdF, chlorotrifluoroethylene, vinyl fluoride, pentafluoropropylene, perfluorocyclobutene, (perfluoroalkyl)ethylene (e.g., CH4). ２ =CHCF ３ ,CH ２ =CHCF ２ CF ３ ,CH ２ =CHCF ２ CF ２ CF ３ ,CH ２ =CHCF ２ CF ２ CF ２ CF ３ ,CH ２ =CHCF ２ CF ２ CF ２ CF ２ CF ３ Examples include monomers having a fluorine atom, such as ethylene, isobutylene, and pentene (α-olefins), vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, and butyl vinyl ether, and monomers without a fluorine atom, such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, and vinyl caprylate.

[0082] If copolymer 2 has other monomer units, the content of other monomer units relative to the total amount of all units constituting the copolymer is preferably 0.001 to 2.0 mol%, more preferably 0.01 to 1.0 mol%, and even more preferably 0.01 to 0.5 mol%.

[0083] As copolymer 2, copolymers consisting of any combination of units from X1 to X8 described below are preferred. These copolymers may be used individually or in combination of two or more. Because copolymer 2 has excellent crosslinking reactivity, and the crosslinked product also has excellent mechanical properties, heat resistance, chemical resistance (alkali resistance, etc.), oil resistance, and weather resistance, X1, X2, X4, X5, X6, and X8 are more preferred, X1, X5, and X8 are even more preferred, and X8 is particularly preferred.

[0084] X1: A combination of TFE units and P units. X2: A combination of TFE units, P units, and VdF units. X3: A combination of TFE units, P units, and PPVE units. X4: A combination of TFE units, P units, and PMVE units. X5: A combination of TFE units, P units, and 9 compound units. X6: A combination of TFE units, P units, 9 compound units, and VdF units. X7: A combination of TFE units, P units, 9 compound units, and PPVE units. X8: A combination of TFE units, P units, 9 compound units, and PMVE units.

[0085] The molar ratio or content of each unit constituting each copolymer of X1 to X8 is preferably within the following numerical range. When the molar ratio or content of each unit constituting each copolymer of X1 to X8 is within the following numerical range, the crosslinking reactivity of the copolymer is further improved, and the mechanical properties, heat resistance, chemical resistance (alkali resistance, etc.), oil resistance, and weather resistance of the crosslinked product are further improved.

[0086] X1: TFE units / P units = 40 / 60 to 60 / 40 (mol ratio). X2: Of the total units constituting X2, the content of TFE units is 40-59 mol%, the content of P units is 40-59 mol%, and the content of VdF units is 1-10 mol%. X3: Of the total units constituting X3, the content of TFE units is 30-60 mol%, the content of P units is 10-40 mol%, and the content of PPVE units is 10-40 mol%. X4: Of the total units constituting X4, the content of TFE units is 30-60 mol%, the content of P units is 10-40 mol%, and the content of PMVE units is 10-40 mol%. X5: Of the total units constituting X5, the content of TFE units is 40-59.99 mol%, the content of P units is 40-59.99 mol%, and the content of compound 9 units is 0.01-3 mol%. X6: Of the total units constituting X6, the content of TFE units is 40-58.99 mol%, the content of P units is 40-58.99 mol%, the content of compound 9 units is 0.01-3 mol%, and the content of VdF units is 1-10 mol%. X7: Of the total units constituting X7, the content of TFE units is 30-60 mol%, the content of P units is 10-40 mol%, the content of compound 9 units is 0.01-3 mol%, and the content of PPVE units is 10-40 mol%. X8: The total content of all units constituting X8 is 30-60 mol% of TFE units, 10-40 mol% of P units, 0.01-3 mol% of compound 9 units, and 10-40 mol% of PMVE units.

[0087] When copolymer 2 is a binary copolymer consisting of TFE units and P units, the molar ratio of TFE units to P units [TFE units / P units] is preferably 30 / 70 to 99 / 1, more preferably 30 / 70 to 70 / 30, and even more preferably 40 / 60 to 60 / 40. When the molar ratio of TFE units to P units is within the above range, the mechanical properties, heat resistance, chemical resistance (alkali resistance, etc.), oil resistance, and weather resistance of the crosslinked material are further improved.

[0088] The sum of the content of TFE units and P units relative to the total amount of all units constituting copolymer 2 is preferably 99 mol% or more.

[0089] Copolymer 2 can be produced by polymerizing monomer component 2. Here, monomer component 2 refers to the monomer composition that constitutes copolymer 2. Radical polymerization is preferred as the method for polymerizing monomer component 2. As the radical polymerization initiator, a compound having a half-life of 10 hours at a temperature of 0 to 100°C is preferred, and a compound having a half-life of 20 to 90°C is particularly preferred.

[0090] Examples of radical polymerization initiators include azo compounds (such as azobisisobutyronitrile), non-fluorinated diacyl peroxides (such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, and lauroyl peroxide), peroxydicarbonates (such as diisopropyl peroxydicarbonate), peroxyesters (such as tert-butylperoxypivalate, tert-butylperoxyisobutyrate, and tert-butylperoxyacetate), fluorinated diacyl peroxides (such as compound 13 represented by formula 13 below), and inorganic peroxides (such as potassium persulfate, sodium persulfate, and ammonium persulfate). (Z(CF) ２ ) ｒ COO) ２ Formula 13 In Formula 13 above, Z is a hydrogen atom, a fluorine atom, or a chlorine atom, and r is an integer from 1 to 10.

[0091] When using a radical polymerization initiator, it is preferable to polymerize monomer component 2 in the presence of a chain transfer agent. Examples of chain transfer agents include compound 14 represented by the following formula 14, alcohols (methanol, ethanol, etc.), chlorofluorohydrocarbons (1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1-fluoroethane, etc.), and hydrocarbons (pentane, hexane, cyclohexane, etc.). １８ I ２ Equation 14 In the above Equation 14, R １８ This is an alkylene group or perfluoroalkylene group having two or more carbon atoms.

[0092] Examples of compound 14 include 1,4-diiodoperfluorobutane, 1,2-diiodoperfluoroethane, 1,3-diiodoperfluoropropane, 1,5-diiodoperfluoropentane, and 1,6-diiodoperfluorohexane. Among these, 1,4-diiodoperfluorobutane is preferred.

[0093] The storage shear modulus G' of copolymer 2 is preferably 100 to 600 kPa, more preferably 200 to 500 kPa, and even more preferably 200 to 400 kPa. A larger storage shear modulus G' indicates a larger molecular weight of the polymer and a higher density of molecular chain entanglement. When the storage shear modulus G' of copolymer 2 is within the above range, the tensile strength and other mechanical properties of the crosslinked material are further improved.

[0094] Copolymer 2 can be produced by the methods disclosed in International Publication No. 2009 / 119202, International Publication No. 2010 / 053056, etc.

[0095] (Copolymer 3) Copolymer 3 is a copolymer having HFP units and VdF units. Copolymer 3 may also contain units other than HFP units and VdF units.

[0096] The total amount of HFP units and VdF units is preferably 50 to 100 mol% of the total amount of all units constituting copolymer 3. The molar ratio of VdF units to HFP units is preferably 60 / 40 to 95 / 5, more preferably 70 / 30 to 90 / 10, and even more preferably 75 / 25 to 85 / 15. Iodine atoms may be contained in 0.01 to 5.0% by mass relative to the total mass of copolymer 3. Examples of other units besides HFP units and VdF units include chlorotrifluoroethylene, TFE, vinyl fluoride, ethylene, ethylidene norbornene, and vinyl crotonate. The other units are preferably 50 mol% or less, more preferably 30 mol% or less, and even more preferably 10 mol% or less relative to the total amount of units.

[0097] When copolymer 3 further contains TFE units, it is preferable that the total amount of HFP units, VdF units, and TFE units is 50 to 100 moles relative to the total amount of all units constituting copolymer 3. Furthermore, it is preferable that the molar ratio of VdF units to TFE units and HFP units is 50 to 65. Moreover, the molar ratio of TFE units to HFP units is preferably 5 / 45 to 30 / 5, more preferably 15 / 35 to 25 / 10, and even more preferably 20 / 30 to 20 / 15. Additionally, iodine atoms may be included in 0.01 to 5.0% by mass relative to the total mass of copolymer 3.

[0098] <Peroxide> The composition contains a peroxide. As described later, the peroxide functions as a crosslinking agent when molding the composition of this embodiment. By using a peroxide, a crosslinked fluorine-containing copolymer with excellent productivity, heat resistance, and chemical resistance can be obtained.

[0099] Examples of peroxides include dialkyl peroxides, dibenzoyl peroxides, tert-butylperoxyacetate, tert-butylperoxyisopropyl carbonate, tert-butylperoxybenzoate, tert-butylperoxybenzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyn-3, α,α'-bis(tert-butylperoxy)-p-diisopropylbenzene, α,α'-bis(tert-butylperoxy)-m-diisopropylbenzene, and 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane. These may be used individually or in combination of two or more.

[0100] Examples of dialkylperoxides include 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxyperoxide, tert-butylcumylperoxide, dicumylperoxide, di(tert-butyl)peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexine, tert-butylperoxymaleic acid, and diisopropylperoxydicarbonate.

[0101] The peroxide content per 100 parts by mass of the fluorine-containing copolymer is preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 5 parts by mass. When the peroxide content is within the above range, productivity, heat resistance, and chemical resistance are further improved.

[0102] (Other Crosslinking Agents) Examples of other crosslinking agents besides peroxides include polyols and polyamines. Examples of polyamines include 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,2-bis(3-amino-4-anilinophenyl)hexafluoropropane, 3,3'-diaminobenzidine, the compound obtained in Synthesis Example 1, the compound obtained in Synthesis Example 2, and the compound obtained in Synthesis Example 3 of International Publication No. 2022 / 230706, 4,4'-methylenedianiline, m-phenylenediamine, adipic acid dihydrazide, (CF ２ ) ６ [C(NH ２ )=NC(=NH)(CF ２ ) ５ CF ３ ] ２ These are some examples. When the composition contains other co-crosslinking agents, the content of the other crosslinking agents per 100 parts by mass of peroxide is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less.

[0103] <Compound C1> Compound C1 is a compound having two or more polymerizable unsaturated bonds in one molecule. However, a compound having two maleimide groups in one molecule shall be treated as compound C2, not compound C1. Compound C1 functions as a cocrosslinking agent. The number of polymerizable unsaturated bonds in one molecule of compound C1 is preferably 2 to 10, more preferably 2 to 5, and even more preferably 2 to 3.

[0104] When compound C1 has two polymerizable unsaturated bonds in one molecule, compound C1 is preferably the compound represented by the following formula C1. (CR ２１ R ２２ =CR ２３ ) ２ R ２４ Formula C1 In the above formula C1, R ２１ , R ２２ , and R ２３ Each of these is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２４ This is a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between the carbon-carbon bonds of a perfluoroalkylene group having 1 to 10 carbon atoms. ２１ , multiple R ２２ , and multiple R ２３ Each of them may be the same or different from the others, but it is preferable that they be the same.

[0105] R ２１ , R ２２ , and R ２３ Each of these atoms is preferably a fluorine atom or a hydrogen atom, more preferably all are fluorine atoms or all are hydrogen atoms, and even more preferably all are fluorine atoms.

[0106] R ２４ The chain may be linear, branched, or cyclic, with linear or branched being preferred, and linear being more preferred. ２４ The number of carbon atoms is preferably 2 or more, and more preferably 3 or more. Also, R ２４ The number of carbon atoms is preferably 8 or less, more preferably 7 or less, even more preferably 6 or less, and particularly preferably 5 or less. ２４The number of carbon atoms may be 2 to 8, 2 to 7, 3 to 6, or 3 to 5.

[0107] R ２４ This may be a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds. ２４ The number of etheric oxygen atoms in is preferably 6 or less, and more preferably 3 or less. ２４ The number of etheric oxygen atoms in R is preferably one or more. ２４ The number of etheric oxygen atoms in R is more preferably 1 or 2. ２４ The etheric oxygen atom in R ２４ It is preferable that it be located at the terminal end.

[0108] From the viewpoint of further improving the crosslinking rate and obtaining a crosslinked product with superior compression set, compound C1 is more preferably the compound represented by formula C1-1 or the compound represented by formula C1-2. (CF ２ =CF) ２ R ３１ Formula C1-1 (CH ２ =CH) ２ R ３２ Formula C1-2

[0109] In the above formula C1-1, R ３１ This refers to a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of a perfluoroalkylene group having 1 to 10 carbon atoms.

[0110] In the above formula C1-2, R ３２ This refers to a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of a perfluoroalkylene group having 1 to 10 carbon atoms.

[0111] A specific example of the compound represented by the above formula C1-1 is CF ２ = CFO (CF ２ ) ２ OCF = CF ２ CF ２ = CFO (CF ２ ) ３ OCF = CF ２ CF２ =CFO(CF ２ ) ４ OCF = CF ２ 、CF ２ =CFO(CF ２ ) ６ OCF = CF ２、 CF ２ =CFO(CF ２ ) ８ OCF = CF ２ 、CF ２ =CFO(CF ２ ) ２ OCF(CF ３ )CF ２ OCF = CF ２ 、CF ２ =CFO(CF ２ ) ２ O(CF(CF ３ )CF ２ O) ２ CF = CF ２ 、CF ２ =CFOCF ２ O(CF ２ CF ２ O) ２ CF = CF ２ 、CF ２ =CFO(CF ２ O) ３ (CF(CF ３ )CF ２ O) ２ CF = CF ２ 、CF ２ =CFOCF ２ CF(CF ３ )O(CF ２ ) ２ OCF(CF ３ )CF ２ OCF = CF ２ and CF ２ =CFOCF ２ CF ２ O(CF ２ O) ２ [[ID=IO1]]CF ２ CF ２ OCF = CF ２ are exemplified.

[0112] Among the compounds represented by the above formula C1-1, CF ２ =CFO(CF ２) ３ OCF = CF ２ or CF ２ = CFO (CF ２ ) ４ OCF = CF ２ Preferably, CF ２ = CFO (CF ２ ) ３ OCF = CF ２ This is preferable.

[0113] A specific example of the compound represented by the above formula C1-2 is CH ２ =CH(CF ２ ) ２ CH=CH ２ ,CH ２ =CH(CF ２ ) ４ CH=CH ２ and CH ２ =CH(CF ２ ) ６ CH=CH ２ These are some examples.

[0114] Among the compounds represented by the above formula C1-2, CH ２ =CH(CF ２ ) ６ CH=CH ２ It is preferable.

[0115] When compound C1 has three polymerizable unsaturated bonds in one molecule, the group having the polymerizable unsaturated bonds is preferably an allyl group. Examples of compounds having three allyl groups in one molecule include triallyl isocyanurate, triallyl cyanurate, and trimethylallyl isocyanurate. Among these, triallyl isocyanurate is preferred.

[0116] As compound C1, a compound represented by the above formula C1-2 or a compound having three polymerizable unsaturated bonds in one molecule is preferred, CH ２ =CH(CF ２ ) ２ CH=CH ２ ,CH ２ =CH(CF ２ ) ４ CH=CH ２ ,CH ２ =CH(CF ２ )６ CH=CH ２ Triallyl isocyanurate, triallyl cyanurate, and trimethylallyl isocyanurate are more preferred, CH ２ =CH(CF ２ ) ６ CH=CH ２ Triallyl isocyanurate is even more preferred.

[0117] The content of compound C1 per 100 parts by mass of the fluorine-containing copolymer is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and even more preferably 0.5 to 2 parts by mass. When the content of compound C1 is within the above range, the heat resistance and low-temperature resistance of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition tend to improve.

[0118] <Compound C2> Compound C2 is a compound having two maleimide groups in one molecule. Compound C2 functions as a co-crosslinking agent. In the present invention, by using Compound C1 and Compound C2 in combination as co-crosslinking agents, the heat resistance and low-temperature resistance of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition are easily improved.

[0119] As compound C2, a compound represented by the following formula C2 is preferred from the viewpoint of improving the crosslinking rate and obtaining a crosslinked product with excellent compression set.

[0120] In the above formula C2, R is a divalent organic group.

[0121] The number of carbon atoms in R is preferably 1 to 30. R is preferably a divalent organic group composed of 1 to 30 carbon atoms, 0 to 100 hydrogen atoms, 0 to 100 fluorine atoms, 0 to 10 nitrogen atoms, 0 to 20 oxygen atoms, and 0 to 20 sulfur atoms.

[0122] For R, for example, one group P selected from the group consisting of divalent aliphatic groups, divalent aromatic groups, and divalent heterocyclic groups. １ , and at least two base P １In a group formed by a single bond between two atoms, at least one hydrogen atom is substituted with a fluorine atom. R is at least two groups selected from the group consisting of divalent aliphatic groups, divalent aromatic groups, and divalent heterocyclic groups. １ -O-, -S-, -SO ２ -, -NR Ｌ -, -CO-, -COO-, -CONR Ｌ -, -SO ３ - and -SO ２ NR Ｌ It may also be a group bonded together by at least one group Q selected from the group consisting of -. In that case, at least one hydrogen atom in the above group may be substituted with a fluorine atom. R Ｌ This represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. In particular, from the viewpoint of improving the crosslinking rate and obtaining a crosslinked product with excellent compression set, the group P １ It is preferable that the group is at least one group selected from the group consisting of divalent aliphatic groups and divalent aromatic groups, and it is preferable that the group Q is -O-.

[0123] Examples of divalent aliphatic groups include alkylene groups, alkenylene groups, and alkynylene groups. Divalent aliphatic groups may be linear, branched, or cyclic. Among these, linear alkylene groups are preferred.

[0124] Examples of divalent aromatic groups include phenylene groups and naphthylene groups. Among these, phenylene groups are preferred as the divalent aromatic group. The phenylene group may be any of o-phenylene, m-phenylene, or p-phenylene groups.

[0125] The heterocycle constituting the divalent heterocyclic group is preferably a five-membered or six-membered ring. The heterocycle may be a monocycle or a fused ring. Examples of heterocycles include pyridine rings, piperidine rings, furan rings, thiophene rings, pyrrole rings, quinoline rings, morpholine rings, indole rings, imidazole rings, pyrazole rings, carbazole rings, phenothiazine rings, phenoxazine rings, indoline rings, thiazole rings, pyrazine rings, thiadiazine rings, benzoquinoline rings, and thiadiazole rings.

[0126] Divalent aliphatic groups and divalent aromatic groups may have substituents. Examples of substituents include halogen atoms, cyano groups, nitro groups, hydroxyl groups, aliphatic groups, aromatic groups, and heterocyclic groups.

[0127] R is preferably a divalent organic group represented by the following formula C2-1.

[0128]

[0129] In formula C2-1, m Ｃ m is an integer between 0 and 8. Ｃ If is 0, L is an alkylene group having 1 to 30 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, or an arylene group having 5 to 20 carbon atoms. At least one hydrogen atom in the alkylene group, cycloalkylene group, or arylene group may be substituted with a fluorine atom, or all hydrogen atoms may be substituted with fluorine atoms. Ｃ If the ratio is 1 or greater, L is independently an alkylene group having 1 to 30 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, or an arylene group having 5 to 20 carbon atoms. At least one hydrogen atom in the arylene group may be substituted with a fluorine atom, or all hydrogen atoms may be substituted with fluorine atoms. A is independently a single bond or -O-.

[0130] In formula C2-1, m Ｃ m is preferably an integer between 0 and 6. Ｃ If is 0, L is preferably an alkylene group having 1 to 10 carbon atoms, or an arylene group having 5 to 15 carbon atoms. At least one hydrogen atom in the alkylene group or arylene group may be substituted with a fluorine atom, or all hydrogen atoms may be substituted with fluorine atoms.

[0131] I understand Ｃ If the ratio is 1 or greater, L is preferably an alkylene group having 1 to 10 carbon atoms or an arylene group having 5 to 15 carbon atoms, independently of each other. At least one hydrogen atom in the alkylene group or arylene group may be substituted with a fluorine atom, or all hydrogen atoms may be substituted with fluorine atoms.

[0132] From the viewpoint of further improving the crosslinking rate and obtaining a crosslinked product with superior compression set, compound C2 is preferably a compound represented by the following formula C2A or C2B.

[0133]

[0134] In the above formula C2A, m Ｃ１ L is an integer from 0 to 6, １ Each of these is independently an alkylene group having 1 to 4 carbon atoms, and at least one hydrogen atom or all of the hydrogen atoms in the alkylene group may be substituted with a fluorine atom, A １ Each of these is independently a single bond or -O-. In the above formula C2B, m Ｃ２ L is an integer between 0 and 4. ２ Each of these is independently an o-phenylene group, an m-phenylene group, a p-phenylene group, a perfluoro-o-phenylene group, a perfluoro-m-phenylene group, and a perfluoro-p-phenylene group, and A ２ Each of these is independently either a single bond or an -O- bond.

[0135] From the viewpoint of further improving the crosslinking rate and obtaining a crosslinked product with superior compression set, compound C2 is preferably a compound represented by the following formula C2C or formula C2D.

[0136]

[0137] In the above formula C2C, p is an integer from 1 to 7. Note that in the above formula C2C, (CH ２ At least one or all of the hydrogen atoms in (CH) may be substituted with fluorine atoms, and if p is 2 or more, p (CH) ２ The q values ​​of Ph (including those substituted with fluorine atoms) may be the same or different. In the above formula C2D, Ph is a phenylene group, and q is an integer from 1 to 5. The phenylene group may be in the ortho, meta, or para position. At least one hydrogen atom or all of the hydrogen atoms of the phenylene group may be substituted with fluorine atoms, and if q is 2 or more, the q Ph values ​​(including those substituted with fluorine atoms) may be the same or different.

[0138] Specific examples of compound C2 that do not contain a fluorine atom include the following compounds A1 to A9. However, compound C2 is not limited to these.

[0139]

[0140]

[0141] Specific examples of compounds C2 containing a fluorine atom include the following compounds A10 to A19. However, compounds C2 are not limited to these.

[0142]

[0143]

[0144] Compound C2 preferably has 2 to 9 atoms forming the main chain that connects the nitrogen atoms of the two maleimide groups. More preferably, the number of atoms forming the main chain that connects the nitrogen atoms of the two maleimide groups is 3 or more. Furthermore, it is more preferable that the number of atoms forming the main chain that connects the nitrogen atoms of the two maleimide groups is 8 or less. "The number of atoms forming the main chain that connects the nitrogen atoms of the two maleimide groups" means the number of atoms when tracing the shortest path between the two nitrogen atoms. For example, in the case of compound A1, the number of atoms forming the main chain that connects the nitrogen atoms of the two maleimide groups is 6, and in the case of compound A2, it is 4.

[0145] When compound C2 contains fluorine atoms, the fluorine atom content is preferably 3 to 32 at%. A fluorine atom content of 7 at% or more is more preferable, and 12 at% or more is even more preferable. Furthermore, a fluorine atom content of 29 at% or less is more preferable, and 25 at% or less is even more preferable. The fluorine atom content may be 7 to 29 at% or 12 to 25 at%. Note that the fluorine atom content is... １９ F-NMR (Fluorine-19 Nuclear Magnetic Resonance), １ H-NMR (Proton Nuclear Magnetic Resonance), １３The structure of compound C2 can be analyzed using 13C NMR (carbon-13 nuclear magnetic resonance), and the number of fluorine atoms in compound C2 can be calculated by dividing the number of fluorine atoms in compound C2 by the total number of atoms that make up the fluorine-containing compound.

[0146] When the fluorine atom content of compound C2 is within the above range, its compatibility with fluorine-containing copolymers tends to increase. As a result, compound C2 and the fluorine-containing copolymer are crosslinked at a faster crosslinking rate. Furthermore, self-polymerization of compound C2 molecules is less likely to occur, resulting in excellent crosslinking efficiency.

[0147] In one embodiment, compound C2 is preferably a compound in which R in formula C2 is a divalent aromatic group. Examples of divalent aromatic groups include the groups mentioned above. At least one hydrogen atom in the divalent aromatic group may be substituted with a fluorine atom. In one embodiment, compound C2 is preferably free of fluorine atoms. Examples of compound C2 that is free of fluorine atoms include N,N'-m-phenylenedimaleimide, 4,4-diphenylmethanebismaleimide, phenylmethanemaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, 4-methyl-1,3-phenylenebismaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, and the like. Among these, N,N'-m-phenylenedimaleimide is preferred.

[0148] The content of compound C2 per 100 parts by mass of the fluorine-containing copolymer is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and even more preferably 0.5 to 2 parts by mass. When the content of compound C2 is within the above range, the heat resistance and low-temperature resistance of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition tend to improve.

[0149] (Other co-crosslinking agents) Examples of other co-crosslinking agents other than compound C1 and compound C2 include 1,3,5-triacryloylhexahydro-1,3,5-triazine, triallyl trimellitate, p-quinone dioxime, p,p'-dibenzoylquinone dioxime, dipropargyl terephthalate, diallyl phthalate, N,N',N'',N'''-tetraallyl terephthalamide, vinyl group-containing siloxane oligomers (polymethylvinylsiloxane, polymethylphenylvinylsiloxane, etc.), ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, trimethylolpropane trimethacrylate, divinylbenzene, etc. The content of other co-crosslinking agents relative to 100 parts by mass of compound C1 and compound C2 is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, and may be 0 parts by mass.

[0150] (Other Components) Examples of other components include the following compounds. Examples of fillers include carbon black, fumed silica, wet silica, quartz powder, diatomaceous earth, zinc oxide, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, mica powder, aluminum sulfate, calcium sulfate, barium sulfate, asbestos, graphite, wollastonite, molybdenum disulfide, carbon fiber, aramid fiber, various whiskers, glass fiber, etc. Examples of processing aids include fatty acid derivatives such as sodium stearate and stearamide, natural waxes, synthetic waxes, etc. Examples of dispersing aids include higher fatty acids and their metal amine salts, etc. Examples of plasticizers include phthalic acid derivatives, adipic acid derivatives, and sebaciic acid derivatives. Examples of softeners include lubricating oil, process oil, coal tar, castor oil, and calcium stearate. Examples of anti-aging agents include phenylenediamine, hindered amines, phosphates, quinoline, cresol, phenol, and dithiocarbamate metal salts. Examples of adhesion aids include silane coupling agents and titanate coupling agents. Examples of acid acceptors include metal oxides with an average particle size of 75 nm or more, monovalent or divalent metal hydroxides, and hydrotalcite. Specifically, examples include magnesium hydroxide, aluminum hydroxide, calcium hydroxide, and hydrotalcite. Examples of release agents, neutralizing agents, and catalysts include tri-n-octylphosphine. In addition, colorants, UV absorbers, flame retardants, oil resistance improvers, foaming agents, scorch inhibitors, tackifiers, lubricants, etc., can be added as needed.

[0151] If the composition further contains a metal oxide, the crosslinking reaction is more likely to proceed rapidly and reliably. Examples of metal oxides include divalent metal oxides such as magnesium oxide, calcium oxide, zinc oxide, and lead oxide. The content of the metal oxide is preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the fluorine-containing copolymer. When the content of the metal oxide is within the above range, the hardness of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition is excellent.

[0152] (Composition of the Composition) The content of the fluorine-containing copolymer with respect to the total mass of the composition is preferably 80.0 to 99.9% by mass, more preferably 90.0 to 99.0% by mass, and even more preferably 94.5 to 98.5% by mass. When the content of the fluorine-containing copolymer is within the above range, the heat resistance and low-temperature resistance of the cross-linked product obtained by cross-linking the fluorine-containing copolymer in the composition are likely to be improved.

[0153] The content of the peroxide with respect to the total mass of the composition is preferably 0.10 to 5.00% by mass, more preferably 0.20 to 2.00% by mass, and even more preferably 0.50 to 1.00% by mass. When the content of the peroxide is within the above range, the heat resistance and low-temperature resistance of the cross-linked product obtained by cross-linking the fluorine-containing copolymer in the composition are likely to be improved.

[0154] The content of Compound C1 with respect to the total mass of the composition is preferably 0.10 to 10.00% by mass, more preferably 0.20 to 5.00% by mass, and even more preferably 0.50 to 2.00% by mass. When the content of Compound C1 is within the above range, the heat resistance and low-temperature resistance of the cross-linked product obtained by cross-linking the fluorine-containing copolymer in the composition are likely to be improved.

[0155] The content of Compound C2 with respect to the total mass of the composition is preferably 0.10 to 10.00% by mass, more preferably 0.20 to 5.00% by mass, and even more preferably 0.50 to 3.00% by mass. When the content of Compound C2 is within the above range, the heat resistance and low-temperature resistance of the cross-linked product obtained by cross-linking the fluorine-containing copolymer in the composition are likely to be improved.

[0156] The total content of Compound C1 and Compound C2 with respect to the total mass of the composition is preferably 0.10 to 25.00% by mass, more preferably 0.50 to 10.00% by mass, and even more preferably 1.00 to 5.00% by mass. When the total content of Compound C1 and Compound C2 is within the above range, the heat resistance and low-temperature resistance of the cross-linked product obtained by cross-linking the fluorine-containing copolymer in the composition are likely to be improved.

[0157] The content of compound C2 relative to 100 parts by mass of the total of compound C1 and compound C2 is preferably 1 to 99 parts by mass, more preferably 5 to 90 parts by mass, and even more preferably 20 to 70 parts by mass. When the content of compound C2 is within the above range, the heat resistance and low-temperature resistance of the crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition tend to improve.

[0158] The total content of components other than the fluorine-containing copolymer, peroxide, compound C1, and compound C2 relative to the total mass of the composition is preferably 1.00% by mass or less, and if included, more preferably 0.01 to 0.50% by mass, and even more preferably 0.05 to 0.20% by mass.

[0159] (Method for producing the composition) The composition can be prepared by mixing a fluorine-containing copolymer, a crosslinking agent (peroxide), a co-crosslinking agent (compound C1 and compound C2), and other components as needed, using a kneading method with a kneading device such as a roll, kneader, Banbury mixer, or extruder.

[0160] The Mooney viscosity of the composition is preferably 10 to 130, more preferably 15 to 120, and even more preferably 20 to 100. When the Mooney viscosity is within the above range, the processability and mechanical properties of the crosslinked material are good. The Mooney viscosity of the composition is measured using a Shimadzu SMV-201 in accordance with JIS K6300-1:2013, with an L-shaped rotor having a diameter of 38.1 mm and a thickness of 5.54 mm, at 121°C with a preheating time of 1 minute and a rotor rotation time of 4 minutes.

[0161] The fluorine-containing copolymer in the composition is crosslinked by heating. The composition may be formed into the desired crosslinked shape and then subjected to primary crosslinking to form the crosslinked product, or it may be subjected to primary crosslinking and simultaneously formed into the desired crosslinked shape to form the crosslinked product. Known molding methods such as extrusion molding, injection molding, transfer molding, and press molding can be used to mold the composition.

[0162] The crosslinked product obtained by primary crosslinking may be treated as a molded article as is, or secondary crosslinking may be performed by further heating the crosslinked product obtained by primary crosslinking in an oven using electricity, hot air, steam, etc. as a heat source. It is preferable to perform secondary crosslinking after primary crosslinking in order to sufficiently advance the crosslinking of the fluorine-containing copolymer in the composition, and to decompose and volatilize the residues of other components such as crosslinking agents contained in the crosslinked product, thereby reducing the amount of these components contained in the molded article.

[0163] The crosslinking temperature in primary crosslinking is preferably set according to the type of fluorine-containing copolymer and peroxide used. The crosslinking temperature in primary crosslinking is preferably 200°C or lower, more preferably 190°C or lower, and even more preferably 170°C or lower. If the crosslinking temperature in primary crosslinking is below the above upper limit, the crosslinking of the fluorine-containing copolymer in the composition will not proceed rapidly at the point where the heating device and the composition come into contact, making molding easier. The crosslinking temperature in primary crosslinking is preferably 130°C or higher. If the crosslinking temperature in primary crosslinking is above the above lower limit, the crosslinking of the fluorine-containing copolymer in the composition will proceed sufficiently, and crosslinking will not require a long time. The heating time in primary crosslinking is preferably 5 to 40 minutes, more preferably 10 to 30 minutes.

[0164] In secondary crosslinking, it is preferable to further crosslink the molded product obtained in primary crosslinking at a temperature higher than the temperature of primary crosslinking but 360°C or lower to obtain a crosslinked product.

[0165] The heating temperature for secondary crosslinking is preferably higher than the crosslinking temperature for primary crosslinking and 360°C or lower, in order to sufficiently advance the crosslinking of the fluorine-containing copolymer in the composition and to decompose and volatilize the residue contained in the crosslinked product. The heating temperature for secondary crosslinking is preferably 150 to 360°C, more preferably 200 to 340°C, even more preferably 250 to 340°C, and particularly preferably 260 to 340°C. The heating time for secondary crosslinking is preferably 1 to 48 hours, and more preferably 2 to 24 hours.

[0166] When the crosslinked material is thick, if the crosslinked material obtained from the primary crosslinking is immediately placed in a heating device adjusted to the secondary crosslinking temperature during secondary crosslinking, a temperature difference will occur between the surface and the interior of the crosslinked material. This can cause defects such as cracks or fractures due to differences in thermal shrinkage rates. In such cases, a method of gradually raising the temperature from a low temperature of room temperature (e.g., 25°C) to 50°C to the secondary crosslinking temperature (also called the "step heating method") is used. The heating time in the above-mentioned secondary crosslinking does not include the time required to raise the temperature to the secondary crosslinking temperature.

[0167] Secondary crosslinking can be carried out under air or under an inert gas that does not react with the fluorine-containing copolymer. In particular, if the crosslinked material is thick, or if the crosslinking temperature of the secondary crosslinking is higher than 250°C, it is preferable to carry out the secondary crosslinking under an inert gas. By carrying out secondary crosslinking under an inert gas, the resulting crosslinked material exhibits remarkably excellent heat resistance. The inert gas is not particularly limited as long as it does not react with the fluorine-containing copolymer, but specific examples include nitrogen and argon, with nitrogen being preferred.

[0168] The heating device used for secondary crosslinking is preferably an inert gas oven. In particular, when performing secondary crosslinking on thick crosslinked materials, it is preferable to crosslink them at a temperature of 260 to 340°C under an inert gas atmosphere. A thick crosslinked material refers to a crosslinked material in which the thickness of the thinnest part is 5 mm or more. The crosslinked material obtained from the composition of this embodiment is a molded article formed into a shape according to the purpose.

[0169] The crosslinked material is suitable for materials such as O-rings, sheets, gaskets, oil seals, diaphragms, and V-rings. Furthermore, the crosslinked material of this disclosure can be applied to heat-resistant and chemical-resistant sealing materials, heat-resistant and oil-resistant sealing materials, wire insulation materials, sealing materials for semiconductor equipment, corrosion-resistant rubber paints, sealing materials for urea-based greases, rubber paints, adhesive rubber, hoses, tubes, calender sheets (rolls), sponges, rubber rolls, components for oil drilling, heat dissipation sheets, solution crosslinked materials, rubber sponges, bearing seals, linings, insulating sheets for automobiles, insulating sheets for electronic equipment, rubber bands for watches, packings for endoscopes, bellows hoses, packings / valves for water heaters, fenders, fibers / nonwoven fabrics (protective clothing, etc.), substrate sealing materials, rubber gloves, stators for single-screw eccentric pumps, components for urea SCR systems, vibration dampers, vibration suppressors, sealing agents, additives to other materials, and toys.

[0170] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0171] Fluorine-containing copolymers Fluorine-containing copolymer 1: A fluorine-containing copolymer having TFE units, PMVE units, and C3DVE units. The molar ratio of each unit is TFE units:PMVE units:C3DVE units = 65.00:35.00:0.10. It contains 0.1% by mass of iodine atoms relative to the total mass of the fluorine-containing copolymer. Fluorine-containing copolymer 2: A fluorine-containing copolymer having TFE units, PMVE units, and C3DVE units. The molar ratio of each unit is TFE units:PMVE units:C3DVE units = 71.00:29.00:0.10. It contains 0.1% by mass of iodine atoms relative to the total mass of the fluorine-containing copolymer. It can be manufactured by the method disclosed in Japanese Patent Publication No. 5644504. • Crosslinking agent (peroxide): 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (manufactured by NOF Corporation, product name: Perhexa 25B). In Table 1, this is represented as "P25B". • Co-crosslinking agent (compound C1): TAIC: triallyl isocyanurate (manufactured by Mitsubishi Chemical Corporation, product name: TAIC). In Table 1, this is represented as "TAIC". C6DV: CH ２ =CH(CF ２ ) ６ CH=CH ２In Table 1, this is represented as "C6-DV". • Co-crosslinking agent (compound C2) N,N'-m-phenylenedimaleimide (manufactured by Yamato Chemical Industries, Ltd., product name: BMI-3000). In Table 1, this is represented as "BMI". • Other components TOCP: Tri-n-octylphosphine. In Table 1, this is represented as "TOCP".

[0172] <Characterization of Crosslinked Materials> (Compression Set) The heat resistance and low-temperature resistance of the crosslinked materials were evaluated by the following methods. Three P26 O-ring test specimens were prepared in accordance with JIS B 2401-1:2012. In accordance with JIS K 6262:2013, the compression set (%) when the prepared test specimens were held at 200°C for 70 hours was calculated for each specimen to obtain the "heat-resistant compression set". In addition, in accordance with JIS K 6262:2013, the compression set (%) when the prepared test specimens were held at 200°C for 70 hours and then held at 25°C for 30 minutes or 24 hours was calculated for each specimen to obtain the low-temperature compression set. In Table 1, the compression set (%) after holding at 25°C for 30 minutes is shown as "Low-temperature compression set (30 minutes)", and the compression set (%) after holding at 25°C for 24 hours is shown as "Low-temperature compression set (24 hours)". The compression set was calculated based on the following formula. The test was conducted using three test specimens, and the arithmetic mean of the values ​​calculated for the three test specimens was recorded. The closer the compression set is to 0%, the better the recovery of the crosslinked material, that is, the better the crosslinking. In the table, "-" indicates that measurement was not taken. Compression set (%) = (Original thickness of test specimen - Thickness 30 minutes after removing the test specimen from the compression device) ÷ (Original thickness of test specimen - Thickness of spacer) × 100 For "Heat-resistant compression set", a value of 20% or less is considered acceptable. That is, if the "Heat-resistant compression set" is 20% or less, it is judged to have excellent heat resistance. For the "low-temperature compression set (30 minutes)," a value of 20% or less is considered acceptable. In other words, if the "low-temperature compression set (30 minutes)" is 20% or less, it is judged to have excellent low-temperature resistance. For the "low-temperature compression set (24 hours)," a value of 80% or less is considered acceptable. In other words, if the "low-temperature compression set (24 hours)" is 80% or less, it is judged to have excellent low-temperature resistance.

[0173] (Hardness) Three test specimens were prepared by punching out a plate-shaped crosslinked material (1 mm thick) with a No. 4 dumbbell. The hardness (Shore-A) of the prepared test specimens was measured using a Type A durometer in accordance with JIS K6253-3:2012. The test was performed using three test specimens, and the arithmetic mean of the measured values ​​of the three test specimens was recorded. An automatic rubber hardness tester (product name "DigiTest", manufactured by H. Barleys) was used as the measuring device.

[0174] (Examples 1-9) Examples 1, 5-8 are examples, and Examples 2-4 and 9 are comparative examples. Compositions were prepared by kneading the ingredients in an open roll for 10 minutes according to Table 1. In Table 1, the unit for each ingredient is parts by mass, and a blank space means that the ingredient was not added. Next, the obtained composition was subjected to one of the following crosslinking conditions 1-3 to crosslink the fluorine-containing copolymer in the composition. The crosslinking conditions are shown in Table 1. The compression set and hardness of the obtained crosslinked product were evaluated. The evaluation results are shown in Table 1.

[0175] (Crosslinking conditions 1) Primary crosslinking: The material was placed in a mold heated to 150°C and held at 150°C for 20 minutes using a hot press. Secondary crosslinking: The material was held at 250°C (oven temperature) for 4 hours in an air atmosphere using an oven.

[0176] (Crosslinking conditions 2) Primary crosslinking: The material was placed in a mold heated to 160°C and held at 160°C for 20 minutes using a hot press. Secondary crosslinking: The material was held at 250°C (oven temperature) for 4 hours in an air atmosphere using an oven.

[0177] (Crosslinking conditions 3) Primary crosslinking: The material was placed in a mold heated to 170°C and held at 170°C for 10 minutes using a hot press. Secondary crosslinking: In an air atmosphere, the material was heated in an oven from 90°C (oven temperature) to 200°C (oven temperature) over 2 hours, held at 250°C (oven temperature) for 4 hours, then heated to 305°C (oven temperature) over 2 hours, and held at 305°C (oven temperature) for 12 hours.

[0178]

[0179] As shown in Table 1, in Examples 1, 5-8, which used compositions containing a fluorine-containing copolymer, a peroxide, compound C1, and compound C2, the resulting crosslinked products exhibited excellent heat resistance and low-temperature resistance. In Examples 2 and 3, which did not contain compound C2, and in Example 4, which did not contain compound C1, the resulting crosslinked products exhibited poor heat resistance and low-temperature resistance. Furthermore, in Example 9, which did not contain compound C2, the resulting crosslinked product exhibited poor low-temperature resistance.

[0180] The crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition of the present invention is suitable for use in harsh environments where crosslinked hydrocarbon copolymers cannot be applied. Specifically, examples include O-rings, gaskets, sealing parts, valves, etc., in automobiles, ships, aircraft, general machinery, chemical plants, industrial equipment, robot parts, etc. The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2024-188295, filed on October 25, 2024, are incorporated herein by reference as disclosure of the specification of the present invention.

Claims

A composition containing a fluorine-containing copolymer, a peroxide, compound C1 having two or more polymerizable unsaturated bonds in one molecule, and compound C2 having two maleimide groups in one molecule. 　 The composition according to claim 1, wherein the content of compound C1 per 100 parts by mass of the fluorine-containing copolymer is 0.01 to 5 parts by mass. 　 The composition according to claim 1, wherein the content of compound C2 per 100 parts by mass of the fluorine-containing copolymer is 0.01 to 5 parts by mass. 　 The composition according to claim 1, wherein the content of compound C2 is 1 to 99 parts by mass relative to 100 parts by mass of the total of compound C1 and compound C2. 　 The composition according to claim 1, wherein the fluorine-containing copolymer is a fluorine-containing copolymer having units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether). 　 The composition according to claim 1, wherein the compound C1 is a compound represented by the following formula C1. (CR ２１ R ２２ = CR ２３ ) ２ R ２４ Formula C1 In the formula C1, R ２１ , R ２２ , and R ２３ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ２４ is a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the end of a perfluoroalkylene group having 1 to 10 carbon atoms or between carbon-carbon bonds. A plurality of R ２１ , a plurality of R ２２ , and a plurality of R ２３ may be the same as or different from each other. 　 The composition according to claim 1, wherein compound C1 is a compound having three allyl groups in one molecule. 　 The composition according to claim 1, wherein the compound C2 is a compound represented by the following formula C2. In the above formula C2, R is a divalent aromatic group, and at least one hydrogen atom in the divalent aromatic group may be substituted with a fluorine atom. 　 The composition according to claim 8, wherein the compound C2 is N,N'-m-phenylenedimaleimide. 　 A crosslinked product obtained by crosslinking the fluorine-containing copolymer in the composition according to any one of claims 1 to 9.

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