Crosslinked rubber article and production method therefor

Abstract

A crosslinked rubber article comprising: a crosslinked rubber that is a crosslinked product of a fluorine-containing-copolymer-containing composition containing a fluorine-containing copolymer; and solid content that is derived from a mold release agent adhered to the surface of the crosslinked rubber, wherein the crosslinked rubber exhibits a contact angle with the mold release agent of 30° or more.

Description

Crosslinked rubber articles and methods for manufacturing the same

[0001] This invention relates to crosslinked rubber articles and methods for manufacturing the same, and more particularly to crosslinked rubber articles with reduced bleeding and methods for manufacturing the same.

[0002] Crosslinked rubber articles, formed by crosslinking fluorine-containing copolymers, are widely used in fields such as vehicles, ships, aircraft, general machinery, and construction as sealing materials (e.g., O-rings, packings, oil seals, gaskets) and cushioning materials due to their excellent heat resistance, chemical resistance, oil resistance, and weather resistance. In particular, their excellent heat resistance makes them suitable for drilling components, such as those used in oil drilling, furnace components, and components for semiconductor integrated circuit manufacturing equipment.

[0003] As a fluorine-containing copolymer-containing composition used to obtain such crosslinked rubber articles, Patent Document 1 discloses a fluorine rubber composition (fluorine-containing copolymer-containing composition) comprising a fluorine rubber (fluorine-containing copolymer) obtained by copolymerizing vinylidene fluoride and at least one other ethylenically unsaturated monomer copolymerizable therewith, an organic peroxide, at least one selected from divalent metal hydroxides and divalent metal oxides, and an organophosphorus compound.

[0004] Japanese Patent Application Publication No. 06-306236

[0005] Although the fluororubber composition (fluorine copolymer-containing composition) described in Patent Document 1 can be vulcanized inexpensively and easily with organic peroxides, the suppression of bleeding in the crosslinked rubber article, which is the crosslinked product of the composition, was not always sufficient. The present invention has been made in view of this situation, and aims to provide a crosslinked rubber article with reduced bleeding and a method for manufacturing the same.

[0006] As a result of diligent research, the inventors have found that a crosslinked rubber article comprising a crosslinked rubber, which is a crosslinked product of a fluorine-containing copolymer-containing composition containing a fluorine-containing copolymer, and solid components derived from a mold release agent having predetermined properties attached to the surface of the crosslinked rubber, exhibits reduced bleeding. The present invention was completed based on these findings.

[0007] The present invention is as follows: [1] A crosslinked rubber article comprising a crosslinked rubber which is a crosslinked product of a fluorine-containing copolymer-containing composition containing a fluorine-containing copolymer, and solid components derived from a mold release agent attached to the surface of the crosslinked rubber, wherein the crosslinked rubber has a contact angle of 30° or more with the mold release agent. [2] The crosslinked rubber article according to [1], wherein the fluorine-containing copolymer has units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), and the molar ratio (tetrafluoroethylene / perfluoro(alkyl vinyl ether)) of the units based on tetrafluoroethylene to the units based on perfluoro(alkyl vinyl ether) is 60 to 80 / 20 to 40. [3] The crosslinked rubber article according to [1] or [2], wherein the mold release agent is a silicone-based mold release agent. [4] The crosslinked rubber article according to [1] or [2], wherein the mold release agent is a fluorine-based mold release agent. [5] The crosslinked rubber article according to [3], wherein the silicone-based release agent comprises at least one selected from the group consisting of silicone oil and polysilsesquioxane. [6] The crosslinked rubber article according to [4], wherein the fluorine-based release agent comprises at least one selected from the group consisting of fluorine-based polymers, fluorine-based surfactants, fluorine-containing organophosphorus compounds, and fluorine compounds including polytetrafluoroethylene. [7] The crosslinked rubber article according to [6], wherein the content of the fluorine-based polymer in 100% by mass of the fluorine-based release agent is 5% by mass or less. [8] A method for producing a crosslinked rubber article according to any one of [1] to [7], comprising applying the release agent to the surface of a fluorine-containing copolymer-containing composition containing the fluorine-containing copolymer, and crosslinking the fluorine-containing copolymer-containing composition on which the release agent is applied. [9] The method for producing a crosslinked rubber article according to [8] above, wherein the fluorine-containing copolymer has units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), and the molar ratio of the units based on tetrafluoroethylene to the units based on perfluoro(alkyl vinyl ether) (tetrafluoroethylene / perfluoro(alkyl vinyl ether)) is 60 to 80 / 20 to 40.

[10] The method for producing a crosslinked rubber article according to [8] or [9] above, wherein the mold release agent is a silicone mold release agent.

[11] The method for producing a crosslinked rubber article according to [8] or [9] above, wherein the mold release agent is a fluorine mold release agent.

[12] The method for producing a crosslinked rubber article according to

[10] above, wherein the silicone mold release agent comprises at least one selected from the group consisting of silicone oil and polysilsesquioxane.

[13] The method for producing a crosslinked rubber article according to

[11] above, wherein the fluorine mold release agent comprises at least one selected from the group consisting of fluorine polymers, fluorine surfactants, fluorine-containing organophosphorus compounds, and fluorine compounds including polytetrafluoroethylene.

[14] The method for producing a crosslinked rubber article according to

[13] above, wherein the content of the fluorine polymer in 100% by mass of the fluorine mold release agent is 5% by mass or less.

[15] A method for manufacturing a crosslinked rubber article according to any one of [8] to

[14] above, wherein the crosslinked rubber article obtained by the crosslinking is subjected to secondary crosslinking under conditions of 50 to 400°C and 1 minute to 48 hours.

[0008] According to the present invention, it is possible to provide a crosslinked rubber article in which the occurrence of bleeding is reduced, and a method for manufacturing the same.

[0009] The definitions and meanings of terms and notations used herein are given below. In this specification, preferred provisions can be adopted at will, and combinations of preferred provisions are considered more preferred. In this specification, the notation "XX to YY" means "XX or more and YY or less". In this specification, the lower and upper limits of preferred numerical ranges (e.g., ranges of content, etc.) described in steps can be combined independently. For example, from the notation "preferably 10 to 90, more preferably 30 to 60", the "preferred lower limit (10)" and the "more preferred upper limit (60)" can be combined to get "10 to 60". Also, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. In this specification, "unit" is a general term for atomic groups derived from one monomer molecule directly formed by the polymerization of monomers, and atomic groups obtained by chemically transforming a part of the above atomic group. "Monomer-based units" may also be referred to as "units" below. In this specification, "rubber" means rubber exhibiting the properties defined in JIS K 6200 (2008) and is distinguished from "resin." In this specification, "melting point" means the temperature corresponding to the maximum value of the melting peak measured by differential scanning calorimetry (DSC). In this specification, "solids" means non-volatile components excluding volatile components such as organic solvents. In other words, 100 parts by mass of solids means 100 parts by mass of non-volatile components. In this specification, "(meth)acrylate" is a general term for acrylate and methacrylate, and "(meth)acryloyl" is a general term for acryloyl and methacryloyl. In this specification, "bleed" means a state in which low molecular weight components remaining in the fluorine-containing copolymer seep out onto the surface of the crosslinked rubber article.

[0010] [Crosslinked Rubber Article] The crosslinked rubber article according to an embodiment of the present invention (hereinafter sometimes referred to as "this embodiment") comprises a crosslinked rubber which is a crosslinked product of a fluorine-containing copolymer-containing composition (hereinafter sometimes referred to as "fluorine-containing copolymer-containing composition") containing a fluorine-containing copolymer, and solid matter derived from a mold release agent adhering to the surface of the crosslinked rubber. Furthermore, the crosslinked rubber has a contact angle of 30° or more with the mold release agent. The crosslinked rubber article of this embodiment has such a configuration that the occurrence of bleeding is reduced. The detailed mechanism for this is unknown, but it is presumed to be as follows: Low molecular weight components derived from the fluorine-containing copolymer remaining in the crosslinked rubber have good compatibility with solid matter derived from the mold release agent present on the surface of the crosslinked rubber. It is thought that under processes that apply a certain amount of heat, such as secondary crosslinking, the low molecular weight components are induced by the solid matter derived from the mold release agent and come out onto the surface of the crosslinked rubber. Furthermore, release agents containing fluorine copolymers with a contact angle of less than 30° between the crosslinked rubber and the release agent are thought to have good compatibility between the crosslinked rubber and the solid components derived from the release agent, making them prone to induced bleeding on the crosslinked rubber surface under thermal processes.

[0011] There are no particular limitations on the applications of the crosslinked rubber articles according to this embodiment, and examples include materials such as O-rings, sheets, gaskets, oil seals, diaphragms, and V-rings; sealing materials such as heat-resistant and chemical-resistant sealing materials, heat-resistant and oil-resistant sealing materials, sealing materials for semiconductor manufacturing equipment, sealing materials for liquid crystal display panel manufacturing equipment, sealing materials for light-emitting diode manufacturing equipment, sealing materials for urea-resistant grease, and substrate sealing materials; coatings such as corrosion-resistant rubber coatings and rubber coatings; and sheets such as calender sheets (rolls), heat dissipation sheets, automotive insulating sheets, and insulating sheets for electronic equipment. Examples of applications include wire insulation materials; adhesive rubber; hoses; tubes; sponges; rubber rolls; components for oil drilling; solution crosslinked materials; rubber sponges; bearing seals (resistant to urea grease, etc.); linings (chemical resistant); rubber bands for watches; endoscope packings (amine resistant), packings / valves for water heaters, etc.; corrugated hoses (processed from calender sheets); fenders (marine civil engineering, ships); fibers / nonwoven fabrics (protective clothing, etc.); rubber gloves; stators for single-screw eccentric pumps; components for urea SCR systems; vibration dampers; vibration suppressors; sealing materials; additives to other materials; toys; and more. Among these, sealing materials for semiconductor manufacturing equipment, components for oil drilling, and heat-resistant and chemical-resistant sealing materials are preferred from the viewpoint of reducing the occurrence of bleeding.

[0012] <Crosslinked Rubber> The crosslinked rubber in the crosslinked rubber article according to this embodiment is a crosslinked product of a fluorine-containing copolymer-containing composition described later. There are no particular restrictions on the content of crosslinked rubber in 100% by mass of the crosslinked rubber article, but it is preferably 60.00 to 99.99% by mass, more preferably 70.00 to 99.97% by mass, and particularly preferably 80.00 to 99.95% by mass. If it is above the lower limit, it becomes easier to maintain the mechanical properties of the crosslinked rubber article, and if it is below the upper limit, it becomes easier to reduce the occurrence of bleeding.

[0013] (Fluorine-containing copolymer-containing composition) The components contained in the fluorine-containing copolymer-containing composition are not particularly limited as long as they contain the fluorine-containing copolymer described later, and may or may not contain other fluorine-containing copolymers, crosslinking agents, specific polymerizable compounds, other components, etc. One type of fluorine-containing copolymer may be used, or two or more types may be used in combination.

[0014] -Fluorine-containing copolymer- The fluorine-containing copolymer included as an essential component in the fluorine-containing copolymer-containing composition is a polymer that contains fluorine atoms; exhibits rubber properties through crosslinking; and is not particularly limited as long as it does not have monomer units having carbonyl groups, hydroxyl groups, epoxy groups, and isocyanate groups. However, it is preferably a monomer unit containing fluorine atoms (hereinafter sometimes referred to as "fluorine-containing monomer"), and is more preferably a perfluoropolymer from the viewpoint of reducing the compression set when a crosslinked rubber article is left at a high temperature for a long period of time (for example, the compression set rate when a compression set test is performed after storing a crosslinked rubber article at 250°C for 336 hours). Here, "perfluoropolymer" means a polymer that substantially does not contain hydrogen atoms bonded to carbon atoms, has fluorine atoms instead of hydrogen atoms, and whose main chain consists of a chain of carbon atoms. The side chains of the perfluoropolymer may or may not have polyvalent atoms other than carbon atoms. There are no particular limitations on the polyvalent atoms, but oxygen atoms are preferred. Here, "substantially free of hydrogen atoms" means that the hydrogen atom content in the perfluoropolymer is 0.5% by mass or less. While there are no particular restrictions, it is preferably 0.10% by mass or less, more preferably 0.07% by mass or less, and particularly preferably 0.05% by mass or less. Good heat resistance or chemical resistance is easily obtained when the hydrogen atom content is within the above range. Note that the hydrogen atom content is... １ This can be done using well-known methods such as H-nuclear magnetic resonance (NMR) analysis.

[0015] There are no particular restrictions on fluorine-containing monomers, as long as they contain a fluorine atom and do not have monomer units having a carbonyl group, a hydroxyl group, an epoxy group, or an isocyanate group. Examples include tetrafluoroethylene (hereinafter sometimes referred to as "TFE"), perfluoro(alkyl vinyl ether) (hereinafter sometimes referred to as "PAVE"), vinylidene fluoride (hereinafter sometimes referred to as "VdF"), hexafluoropropylene (hereinafter sometimes referred to as "HFP"), and chlorotrifluoroethylene (hereinafter sometimes referred to as "CTFE"). These may be used individually or in combination of two or more.

[0016] The PAVE unit is a unit based on perfluoro(alkyl vinyl ether). While there are no particular restrictions on the PAVE, it is preferably a monomer represented by formula (1) from the viewpoint of excellent polymerization reactivity and rubber properties (such as compression set heat aging resistance). CF ２ =CF-O-R ｆ１ (1) In formula (1), R ｆ１ This represents a perfluoroalkyl group having 1 to 10 carbon atoms. While there are no particular restrictions on the number of carbon atoms in the perfluoroalkyl group, as long as it is between 1 and 10, it is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 3, from the viewpoint of excellent polymerization reactivity. If the number of carbon atoms is above the lower limit, polymerization reactions become easier, and if it is below the upper limit, the variation in the polymerization reaction over time tends to be smaller. The perfluoroalkyl group may be linear or branched.

[0017] There are no particular restrictions on PAVE, and examples include perfluoro(methyl vinyl ether) (hereinafter sometimes referred to as "PMVE"), perfluoro(ethyl vinyl ether) (hereinafter sometimes referred to as "PEVE"), and perfluoro(propyl vinyl ether) (hereinafter sometimes referred to as "PPVE"). These may be used individually or in combination of two or more. Among these, PMVE and PPVE are preferred from the viewpoint of heat resistance and adhesion, with PMVE being more preferred.

[0018] The fluorine-containing copolymer may or may not have units based on a monomer other than those described above (hereinafter sometimes referred to as "other monomer"). The other monomer is not particularly limited as long as it does not have a monomer unit having a group with a carbonyl group, a hydroxy group, an epoxy group, and an isocyanate group, and examples thereof include a monomer having two or more polymerizable unsaturated bonds (hereinafter sometimes referred to as "DV"), a monomer represented by the following formula (5), ethylene, propylene, and a monomer having a nitrile group (hereinafter referred to as "R ＣＮ ").), and the like. Further, examples also include monomers having a halogen atom other than the monomers represented by the above-mentioned fluorine-containing monomer and other monomers (hereinafter sometimes referred to as "other monomer having a halogen atom") (for example, bromotrifluoroethylene, iodotrifluoroethylene). These may be used alone or in combination of two or more thereof.

[0019] The DV unit is a unit based on a monomer having two or more polymerizable unsaturated bonds. The polymerizable unsaturated bond is not particularly limited, and examples thereof include a carbon atom-carbon atom double bond (C=C), a carbon atom-carbon atom triple bond (C≡C), and the like. The number of polymerizable unsaturated bonds in DV is not particularly limited, but is preferably 2 to 6, more preferably 2 or 3, and particularly preferably 2. When the number is not less than the above lower limit, the amount of DV added in the fluorine-containing copolymer can be easily controlled, and when the number is not more than the above upper limit, the viscosity of the fluorine-containing copolymer can be easily controlled. The DV is not particularly limited, but from the viewpoint that the compression set of the crosslinked rubber article at a high temperature is further reduced, the DV preferably further has a fluorine atom, and more preferably is a monomer represented by the following formula (2). (CR ２１ R ２２ =CR ２３ ) ａ２ R ２４ (2) In formula (2), R ２１ , R ２２ , and R ２３ each independently represent a hydrogen atom, a fluorine atom, a methyl group, or a perfluoromethyl group, a2 represents an integer of 2 to 6, and R ２４This represents a divalent perfluorohydrocarbon group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of the perfluorohydrocarbon group. Multiple R ２１ , multiple R ２２ , and multiple R ２３ Each of them may be the same or different from each other. It is preferable that they are the same. There are no particular restrictions on the integer a2, but it is preferably 2 or 3, more preferably 2.

[0020] R ２１ , R ２２ , and R ２３ While there are no particular restrictions, from the viewpoint of excellent polymerization reactivity of DV, it is preferable that each atom be independently a fluorine atom or a hydrogen atom, more preferably all being fluorine atoms or hydrogen atoms, and from the viewpoint of excellent heat resistance and chemical resistance of the crosslinked rubber article, it is particularly preferable that all be fluorine atoms. ２４ The chain may be linear, branched, or cyclic. Of these, linear or branched is preferred, and linear is more preferred. ２４ The number of carbon atoms is not particularly limited as long as it is between 1 and 10, but is preferably 2 to 8, more preferably 3 to 7, even more preferably 3 to 6, and most preferably 3 to 5. ２４ It may or may not have etheric oxygen atoms. Among these, it is preferable that it has etheric oxygen atoms from the viewpoint of superior crosslinking reactivity and rubber properties (compression set, low-temperature durability, etc.). ２４ If the compound has etheric oxygen atoms, there are no particular restrictions on the number of etheric oxygen atoms, but it is preferably 1 to 6, more preferably 1 to 3, and most preferably 1 or 2. ２４ There are no particular restrictions on the etheric oxygen atom in, but R is preferred. ２４ It is located at the very end of the structure.

[0021] There are no particular restrictions on the monomer represented by formula (2), but it is preferably the monomer represented by the following formula (3) or the monomer represented by the following formula (4).

[0022] (CF ２ =CF) ２ R ３１ (3) In formula (3), R ３１ This represents a divalent perfluorohydrocarbon group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of the perfluorohydrocarbon group.

[0023] There are no particular restrictions on the monomer represented by formula (3), for example, CF ２ = CFO (CF ２ ) ２ OCF = CF ２ CF ２ = CFO (CF ２ ) ３ OCF = CF ２ (Hereafter, this may also be referred to as "C3DVE"), CF ２ = CFO (CF ２ ) ４ OCF = CF ２ (Hereafter, this may also be referred to as "C4DVE"), 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 O(CF(CF３ )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 and the like. These may be used alone, or two or more thereof may be used in combination. Among these, C3DVE and C4DVE are preferred.

[0024] (CH ２ =CH) ２ R ４１ (4) In formula (4), R ４１ represents a divalent perfluorohydrocarbon group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal of the perfluorohydrocarbon group or between carbon-carbon bonds.

[0025] The monomer represented by formula (4) is not particularly limited, and examples thereof include 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 (hereinafter sometimes referred to as "C6DV") and the like. These may be used alone, or two or more thereof may be used in combination. Among these, C6DV is preferred.

[0026] When the aforementioned DV is copolymerized, the polymerizable double bond at the terminal of DV reacts during polymerization, and a fluorine-containing copolymer having branched chains is obtained.

[0027] Equation (5) is as follows: CF ２ =CF-O-R ｆ２ (5) In formula (5), R ｆ２ This represents a perfluoroalkyl group containing 1 to 5 etheric oxygen atoms with 1 to 8 carbon atoms. ｆ２ There are no particular restrictions on the number of carbon atoms, but it is preferably 1 to 6, more preferably 1 to 5.

[0028] There are no particular restrictions on the monomer represented by formula (5), and examples include perfluoro(3,6-dioxa-1-heptene), perfluoro(3,6-dioxa-1-octene), and perfluoro(5-methyl-3,6-dioxa-1-nonene). These may be used individually or in combination of two or more.

[0029] R ＣＮ The nitrile group in the unit has the function of being a site for forming a crosslinked structure, R ＣＮ Fluorine-containing copolymers having units can efficiently form crosslinks, and as a result, crosslinked materials of fluorine-containing copolymer-containing compositions containing such copolymers tend to have good heat resistance. ＣＮ While there are no particular restrictions, from the viewpoint of obtaining a crosslinked rubber article with a smaller compression set at high temperatures, it is preferable that it has a fluorine atom, and more preferably that it is a monomer represented by formula (6). CR ６１ R ６２ =CR ６３ -R ６４ -CN (6) In formula (6), R ６１ , R ６２ , and R ６３ Each of these independently represents a hydrogen atom, a fluorine atom, or a methyl group, R ６４ This represents a divalent perfluorohydrocarbon group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of the perfluorohydrocarbon group.

[0030] R ６１ , R ６２ , R ６３ There are no particular restrictions, however R ＣＮFrom the viewpoint of having excellent polymerization reactivity, preferably each is independently a fluorine atom or a hydrogen atom, more preferably R ６１ , R ６２ , and R ６３ All of them are fluorine atoms or hydrogen atoms, and from the viewpoint of having superior release properties and heat resistance of the crosslinked rubber article, R is particularly preferred. ６１ , R ６２ , and R ６３ All of them are fluorine atoms. ６４ It may or may not have an etheric oxygen atom. Among these, it is preferable that it has an etheric oxygen atom from the viewpoint of having superior rubber properties. ６４ There are no particular restrictions on the number of etheric oxygen atoms in the mixture, but it is preferably 1 to 3, more preferably 1 or 2.

[0031] There are no particular restrictions on the monomer represented by formula (6), for example, CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CN (hereinafter sometimes referred to as "8CNVE"), CF ２ = CFO (CF ２ ) ５ CN (hereinafter sometimes referred to as "MV5CN"), CF ２ = CFOCF ２ CF ２ CF ２ OCF (CF ３ ) CN, CF ２ = CFO (CF ２ ) ３ Examples include CN. These may be used individually or in combination of two or more. Among these, 8CNVE and MV5CN are preferred from the viewpoint of providing superior release properties and heat resistance for crosslinked rubber articles.

[0032] There are no particular restrictions on the units contained in the fluorine-containing copolymer, but the following combinations are preferred: Combination 1: A combination of TFE units and PAVE units Combination 2: A combination of TFE units, PAVE units, and DV units Combination 3: A combination of VdF units and HFP units Combination 4: A combination of VdF units, HFP units, and TFE units Combination 5: A combination of TFE units, PAVE units, and R ＣＮ Of these combinations with units, combinations 1, 2, and 5 are more preferred from the viewpoint of providing excellent heat resistance and chemical resistance for crosslinked rubber articles, with combinations 2 and 5 being particularly preferred.

[0033] There are no particular restrictions on the monomers used in combinations 1 to 5, but the following molar ratios are preferred. These molar ratios tend to result in superior heat resistance and chemical resistance of the crosslinked rubber article. Combination 1 (molar ratio): TFE units / PAVE units = preferably 60-80 / 20-40, more preferably 65-80 / 20-35, particularly preferably 70-80 / 20-30 Combination 2 (molar ratio): TFE units / PAVE units / DV units = 60-80 / 20-40 / 0.01-1, more preferably 65-80 / 20-35 / 0.05-1, particularly preferably 70-80 / 20-30 / 0.1-1 Combination 3 (molar ratio): VdF units / HFP units = 60-95 / 5-40 Combination 4 (molar ratio): VdF units / HFP units / TFE units = 30-50 / 5-45 / 5-65 Combination 5 (molar ratio): TFE units / PAVE units / R ＣＮ Units = 60-80 / 20-40 / 0.1-1, more preferably 65-80 / 20-35 / 0.2-1, particularly preferably 70-80 / 20-30 / 0.4-1

[0034] Fluorine-containing copolymers may or may not contain iodine atoms. If iodine atoms are present, there are no particular restrictions, but it is preferable that the iodine atoms be at the ends of the fluorine-containing copolymer (polymer chain). There are no particular restrictions on the iodine atoms, but examples include iodine atoms derived from iodine compounds that function as chain transfer agents as described later; iodine atoms in units based on monomers containing iodine atoms among other halogen atoms such as iodotrifluoroethylene mentioned above; and so on. These may be used individually or in combination of two or more. Among these, iodine atoms derived from iodine compounds that function as chain transfer agents are preferred. When a fluorine-containing copolymer contains iodine atoms, there are no particular restrictions on the iodine atom content in 100% by mass of the fluorine-containing copolymer, but it is preferably 0.01 to 5.0% by mass, more preferably 0.05 to 2.0% by mass, and particularly preferably 0.05 to 1.0% by mass. If it is above the lower limit, the crosslinking reactivity of the fluorine-containing copolymer improves, and the mechanical properties of the crosslinked rubber article tend to be superior.

[0035] There are no particular restrictions on the content of the fluorine-containing copolymer in 100% by mass of the fluorine-containing copolymer-containing composition, but it is preferably 60.0 to 99.5% by mass, more preferably 70.0 to 99.5% by mass, and particularly preferably 80.0 to 99.5% by mass.

[0036] - Method for producing fluorine-containing copolymers - There are no particular limitations on the method for producing fluorine-containing copolymers, and examples include copolymerizing the above monomers in the presence of a radical polymerization initiator.

[0037] There are no particular restrictions on the radical polymerization initiator, but water-soluble polymerization initiators and redox polymerization initiators are preferred. There are no particular restrictions on the water-soluble polymerization initiators, and examples include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, and organic polymerization initiators such as disuccinic acid peroxide and azobisisobutylamidine dihydrochloride. These may be used individually or in combination of two or more. Among these, persulfates are preferred, and ammonium persulfate is more preferred. There are no particular restrictions on the redox polymerization initiators, and examples include polymerization initiators combining persulfates and reducing agents. Of these, polymerization initiators capable of polymerizing each monomer in the polymerization temperature range of 0 to 85°C are preferred. There are no particular restrictions on the persulfates constituting the redox polymerization initiator, and examples include alkali metal salts of persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. These may be used individually or in combination of two or more. Among these, ammonium persulfate is preferred. There are no particular restrictions on the reducing agent to be combined with persulfates, and examples include thiosulfates, sulfites, bisulfites, pyrosulfites, and hydroxymethanesulfinates. These may be used individually or in combination of two or more. Among these, hydroxymethanesulfinates are preferred, and sodium hydroxymethanesulfinate is more preferred.

[0038] In the method for producing a fluorine-containing copolymer, the monomer may be copolymerized together with a radical polymerization initiator in the presence of a chain transfer agent. There are no particular restrictions on the chain transfer agent, but from the viewpoint of availability, an iodine compound is preferred, more preferably a compound of formula RI ２ This is an iodine compound represented by the formula RI. In the above formula, R represents an alkylene group or perfluoroalkylene group having 3 or more carbon atoms (preferably 3 to 8 carbon atoms). ２There are no particular restrictions on the iodine compound represented by , and examples include 1,3-diiodopropane, 1,4-diiodobutane, 1,6-diiodohexane, 1,8-diiodooctane, 1,3-diiodoperfluoropropane, 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 1,8-diiodoperfluorooctane. These may be used individually or in combination of two or more. There are no particular restrictions on the iodine compound, but from the viewpoint of reaction stability, an iodine compound having a perfluoroalkylene group is preferred, and more preferably 1,4-diiodoperfluorobutane. By copolymerizing the above monomers in the presence of an iodine compound, iodine atoms can be introduced into the fluorine-containing copolymer.

[0039] For details on components other than those mentioned above used in the production of fluorine-containing copolymers and the production method, refer to the method described in paragraphs 0019 to 0034 of International Publication No. 2010 / 082633.

[0040] -Other Fluorine-containing Copolymers- Other fluorine-containing copolymers are monomers having at least one functional group selected from the group consisting of a carbonyl group, a hydroxyl group, an epoxy group and an isocyanate group (hereinafter sometimes referred to as a "specific functional group") (hereinafter referred to as "R Ｘ It is sometimes referred to as ". It has units and TFE units. The fluorine-containing copolymer-containing composition may or may not contain other fluorine-containing copolymers. Among these, the fluorine-containing copolymer-containing composition is R ＣＮ When it contains a fluorine-containing copolymer having units, R ＣＮ Nitrile group and R Ｘ From the viewpoint of improving the crosslinking efficiency of crosslinked rubber articles and enhancing the mechanical properties of crosslinked rubber articles by utilizing the reaction and bonding with specific functional groups in the material, it is preferable to include other fluorine-containing copolymers.

[0041] Other fluorine-containing copolymers are not particularly limited, but from the viewpoint of reducing compression set at high temperatures, R Ｘ It is preferable that the unit has TFE units and PAVE units.

[0042] The group having a carbonyl group in the specific functional group is not particularly limited as long as it has a carbonyl group in its molecule. Examples include groups having a carbonyl group between the carbon atoms of a hydrocarbon group, carbonate groups, carboxyl groups, haloformyl groups, alkoxycarbonyl groups, acid anhydride residues, polyfluoroalkoxycarbonyl groups, and ester groups. These may be used individually or in combination of two or more. Among these, from the viewpoint of excellent reactivity with nitrile groups, groups having a carbonyl group between the carbon atoms of a hydrocarbon group, carbonate groups, carboxyl groups, haloformyl groups, alkoxycarbonyl groups, and acid anhydride residues are preferred, with carboxyl groups and acid anhydride residues being more preferred.

[0043] There are no particular restrictions on the hydrocarbon group in a group having carbonyl groups between carbon atoms of the hydrocarbon group, but preferably it is a linear or branched alkylene group having 2 to 8 carbon atoms. Note that the number of carbon atoms in the alkylene group does not include the number of carbon atoms in the carbonyl group. The haloformyl group is represented as -C(=O)-X (where X is a halogen atom). There are no particular restrictions on the halogen atom in the haloformyl group, but examples include fluorine atoms and chlorine atoms. Among these, fluorine atoms are preferred. That is, a fluoroformyl group (sometimes called a carbonyl fluoride group) is preferred as the haloformyl group. The alkoxy group in the alkoxycarbonyl group may be linear or branched. There are no particular restrictions on the number of carbon atoms in the alkoxycarbonyl group, but preferably it is 1 to 8, more preferably 1 (methoxy group) or 2 (ethoxy group).

[0044] R Ｘ It may have multiple specific functional groups, or it may have just one. Ｘ If a substance has multiple specific functional groups, the types of these specific functional groups may be the same or different from each other. Ｘ Since it is used as a monomer, it has polymerizable unsaturated bonds. Specific examples of polymerizable unsaturated bonds are as described above. R ＸThere are no particular restrictions, but preferably, the compound has one specific functional group and one polymerizable unsaturated bond.

[0045] R Ｘ There are no particular restrictions on monomers having a carbonyl group as such, for example, monomers having an acid anhydride residue (hereinafter referred to as "R Ｘ１ It is sometimes referred to as "R"), a monomer having a carboxyl group (hereinafter referred to as "R") Ｘ２ It is sometimes referred to as "vinyl ester, (meth)acrylate, CF ２ = CFOR ｆｘ CO ２ X １ (However, R ｆｘ X is a perfluoroalkylene group having 1 to 10 carbon atoms, which may have an etheric oxygen atom. １ These are alkyl groups having 1 to 3 carbon atoms. Examples include [examples omitted]. These may be used individually or in combination of two or more. R Ｘ１ There are no particular restrictions on the types of anhydrides used, but examples include itaconic anhydride (hereinafter sometimes referred to as "IAH"); citraconic anhydride (hereinafter sometimes referred to as "CAH"); 5-norbornene-2,3-dicarboxylic acid anhydride (also known as hymic anhydride; hereinafter sometimes referred to as "NAH"); acid anhydrides of unsaturated dicarboxylic acids such as maleic anhydride; etc. These may be used individually or in combination of two or more. Ｘ２ There are no particular restrictions on this, for example, unsaturated dicarboxylic acids such as itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, and maleic acid; unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; CF ２ = CFOR ｆｘ CO ２ H (however, R ｆｘThis is a perfluoroalkylene group having 1 to 10 carbon atoms, which may have an etheric oxygen atom.) These may be used individually or in combination of two or more. There are no particular restrictions on vinyl esters, and examples include vinyl acetate, vinyl chloroacetate, vinyl butanoate, vinyl pivalate, vinyl benzoate, vinyl crotonate, etc. These may be used individually or in combination of two or more. There are no particular restrictions on (meth)acrylates, and examples include (polyfluoroalkyl)acrylate, (polyfluoroalkyl) methacrylate, etc. These may be used individually or in combination of two or more.

[0046] R Ｘ There are no particular restrictions on monomers having a hydroxyl group as such, and examples include vinyl esters; vinyl ethers; allyl ethers; (meth)acrylate compounds or crotonic acid-modified compounds such as hydroxyethyl crotate, which have one or more hydroxyl groups at the terminal or side chain; allyl alcohols; and the like. Ｘ There are no particular restrictions on the monomer having an epoxy group as the monomer. Examples include unsaturated glycidyl ethers such as allyl glycidyl ether, 2-methylallyl glycidyl ether, and vinyl glycidyl ether; and unsaturated glycidyl esters such as glycidyl acrylate and glycidyl methacrylate. These may be used individually or in combination of two or more. Ｘ There are no particular restrictions on the monomer having an isocyanate group, and examples include unsaturated monomers having an isocyanate group such as 2-(meth)acryloyloxyethyl isocyanate, 2-(2-(meth)acryloyloxyethoxy)ethyl isocyanate, and 1,1-bis((meth)acryloyloxymethyl)ethyl isocyanate. These may be used individually or in combination of two or more.

[0047] R Ｘ There are no particular restrictions, but from the viewpoint of excellent reactivity with nitrile groups, it is preferably a monomer having a carbonyl group, and more preferably RＸ１ That is. R Ｘ１ There are no particular restrictions, but from the viewpoint of ease of manufacture of other fluorine-containing copolymers, IAH, CAH, NAH, and more preferably NAH are preferred. Ｘ You may use only one type, or you may use two or more types in combination.

[0048] When other fluorine-containing copolymers have PAVE units, the examples and preferred embodiments of PAVE are the same as those for PAVE in fluorine-containing copolymers.

[0049] Other fluorine-containing copolymers may or may not have units based on the other monomers described above. Examples and preferred embodiments of the other monomers are the same as those for the other monomers in the fluorine-containing copolymers.

[0050] Other fluorine-containing copolymers may have specific functional groups as end groups in the main chain. While there are no particular restrictions on the specific functional groups used as end groups in the main chain, they are preferably alkoxycarbonyl groups, carbonate groups, carboxyl groups, fluoroformyl groups, acid anhydride residues, or hydroxyl groups. These functional groups can be introduced by appropriately selecting radical polymerization initiators, chain transfer agents, etc., which are used in the production of other fluorine-containing copolymers.

[0051] Other fluorine-containing copolymers R Ｘ When it has units, TFE units and PAVE units, R in 100 mol% of the total units of the other fluorine-containing copolymer ＸThere are no particular restrictions on the content of the units, but from the viewpoint of reducing compression set at high temperatures, it is preferably 0.01 to 3.00 mol%, more preferably 0.03 to 2.00 mol%, and particularly preferably 0.05 to 1.00 mol%. In the above case, there are no particular restrictions on the content of TFE units in 100 mol% of the total units of the other fluorine-containing copolymer, but from the viewpoint of reducing compression set at high temperatures, it is preferably 90.00 to 99.89 mol%, more preferably 95.00 to 99.47 mol%, and particularly preferably 96.00 to 98.95 mol%. In the above case, there are no particular restrictions on the content of PAVE units in 100 mol% of the total units of the other fluorine-containing copolymer, but from the viewpoint of reducing compression set at high temperatures, it is preferably 0.10 to 9.99 mol%, more preferably 0.50 to 4.97 mol%, and particularly preferably 1.00 to 3.95 mol%.

[0052] Other fluorine-containing copolymers R Ｘ When it has units, TFE units and HFP units, R in 100 mol% of the total units of the other fluorine-containing copolymer Ｘ There are no particular restrictions on the content of the units, but from the viewpoint of reducing compression set at high temperatures, it is preferably 0.01 to 3.00 mol%, more preferably 0.03 to 2.00 mol%, and particularly preferably 0.05 to 1.00 mol%. In the above case, there are no particular restrictions on the content of TFE units in 100 mol% of the total units of the other fluorine-containing copolymer, but from the viewpoint of reducing compression set at high temperatures, it is preferably 90.00 to 99.89 mol%, more preferably 91.00 to 98.00 mol%, and particularly preferably 92.00 to 97.00 mol%. In the above case, there are no particular restrictions on the content of HFP units in 100 mol% of the total units of the other fluorine-containing copolymer, but from the viewpoint of reducing compression set at high temperatures, it is preferably 0.10 to 9.99 mol%, more preferably 1.00 to 9.00 mol%, and particularly preferably 2.00 to 8.00 mol%.

[0053] When a fluorine-containing copolymer-containing composition contains other fluorine-containing copolymers, there are no particular restrictions on the content of the other fluorine-containing copolymers, but it is preferably 2 to 50 parts by mass, more preferably 3 to 30 parts by mass, even more preferably 3 to 20 parts by mass or less, and particularly preferably 4 to 15 parts by mass or less, per 100 parts by mass of the fluorine-containing copolymer. If the content is above the lower limit, it becomes easier to suppress the occurrence of cracks in the crosslinked rubber article after compression, and if it is below the upper limit, it becomes easier to obtain a crosslinked rubber article with less compression set at high temperatures.

[0054] There are no particular restrictions on the melting point of the other fluorine-containing copolymer, but it is preferably 260 to 320°C, more preferably 280 to 315°C, and particularly preferably 295 to 310°C. If it is above the lower limit, the crosslinked rubber article made from this composition containing the other fluorine-containing copolymer tends to have excellent heat resistance, and if it is below the upper limit, it tends to have excellent processability and the crosslinked rubber article made from this composition containing the other fluorine-containing copolymer tends to have excellent surface smoothness. The melting point of the other fluorine-containing copolymer can be adjusted by the type and content ratio of the units constituting the other fluorine-containing copolymer, molecular weight, etc. For example, the melting point of the other fluorine-containing copolymer tends to rise as the proportion of TFE units increases.

[0055] The melt flow rate (MFR) of the other fluorine-containing copolymer is not particularly limited, but is preferably 1 to 1000 g / 10 min, more preferably 5 to 20 g / 10 min. However, the above MFR is the value measured at a temperature 20°C or more higher than the melting point of the other fluorine-containing copolymer (usually 372°C). If it is above the lower limit, the other fluorine-containing copolymer will have good processability, and the crosslinked rubber article made from this composition containing the other fluorine-containing copolymer will have good surface smoothness. If it is below the upper limit, the other fluorine-containing copolymer will have good mechanical strength, and the crosslinked rubber article made from this composition containing the other fluorine-containing copolymer will have good mechanical strength. MFR is an indicator of the molecular weight of the other fluorine-containing copolymer; a large MFR indicates a small molecular weight, and a small MFR indicates a large molecular weight. The molecular weight of the other fluorine-containing copolymer, and thus the MFR, can be adjusted by the manufacturing conditions of the other fluorine-containing copolymer. For example, shortening the polymerization time during monomer polymerization tends to increase the MFR. The MFR can be measured by the method described in the examples.

[0056] - Other methods for producing fluorine-containing copolymers - An example of a method for producing other fluorine-containing copolymers is a method of copolymerizing the above monomers in the presence of a radical polymerization initiator, the details of which are described in International Publication No. 2016 / 017801.

[0057] There are no particular restrictions on the form of the other fluorine-containing copolymer, but it is preferably in particulate form. That is, it is preferable that the other fluorine-containing copolymer is included in the fluorine-containing copolymer-containing composition in the form of resin particles containing the other fluorine-containing copolymer. The resin particles may or may not contain resins other than the above-mentioned fluorine-containing copolymer and other fluorine-containing copolymers (hereinafter sometimes referred to as "other resins"). There are no particular restrictions on the other resins, and examples include fluorine-containing copolymers other than those described later, such as tetrafluoroethylene-fluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and ethylene-tetrafluoroethylene copolymer; polytetrafluoroethylene; aromatic polyester; polyamide-imide; thermoplastic polyimide; etc. These may be used individually or in combination of two or more. There are no particular restrictions on the content of other fluorine-containing copolymers in 100% by mass of resin particles, but it is preferably 80 to 100% by mass, more preferably 85 to 100% by mass, even more preferably 90 to 100% by mass, and particularly preferably 100% by mass.

[0058] There are no particular restrictions on the average particle size of the resin particles, but it is preferably 0.02 to 50 μm, more preferably 0.02 to 35 μm, and most preferably 0.02 to 10 μm. In this specification, "average particle size of resin particles" means the volume-based cumulative 50% diameter (D50) determined by the laser diffraction-scattering method. That is, the particle size distribution is measured by the laser diffraction-scattering method, the total volume of the particle collection is set to 100% to obtain a cumulative curve, and the average particle size is the particle size at the point on the cumulative curve where the cumulative volume is 50%.

[0059] Resin particles can be produced, for example, by the method for producing resin particles and resin powders described in International Publication No. 2016 / 017801.

[0060] -Crosslinking Agent- The fluorine-containing copolymer-containing composition may or may not contain a crosslinking agent. Among these, it is preferable to include one from the viewpoint of improving the crosslinking efficiency of the fluorine-containing copolymer-containing composition. There are no particular restrictions on the crosslinking agent, and examples include organic peroxides and compounds having two or more amino groups (hereinafter sometimes referred to as "polyamine compounds"). These may be used individually or in combination of two or more.

[0061] The polyamine compound may be a compound in which a hydrogen atom of an aliphatic hydrocarbon is substituted with an amino group, or a compound in which a hydrogen atom of an aromatic hydrocarbon is substituted with an amino group. Among these, a compound in which a hydrogen atom of an aromatic hydrocarbon is substituted with an amino group is preferred from the viewpoint of obtaining a crosslinked rubber article with a smaller compression set at high temperatures. There are no particular restrictions on the polyamine compound, but it is preferable that it contains a fluorine atom from the viewpoint of improving compatibility with fluorine-containing copolymers and obtaining a crosslinked rubber article with a smaller compression set at high temperatures.

[0062] There are no particular restrictions on the polyamine compounds, and examples include hexamethylenediamine, hexamethylenediamine carbamate, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (hereinafter sometimes referred to as "BOAP," also known as bisaminophenol AF), 2,2-bis(3,4-diaminophenyl)propane, 2,2-bis(3,4-diaminophenyl)hexafluoropropane, 2,2-bis(3-amino-4-(N-phenylamino)phenyl)hexafluoropropane, 4,4'-methylenedianiline, m-phenylenediamine, adipic acid dihydrazide, and the compound represented by formula (XII) of Japanese Patent No. 5833657. These may be used individually or in combination of two or more. Among these, BOAP is preferred from the viewpoint of obtaining a cross-linked rubber article with lower compression set at high temperatures.

[0063] There are no particular restrictions on the organic peroxide, and examples include dialkyl peroxides, α,α'-bis(tert-butylperoxy)-p-diisopropylbenzene, α,α'-bis(tert-butylperoxy)-m-diisopropylbenzene, benzoyl peroxide, tert-butylperoxybenzene, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butylcumyl peroxide, and dicumyl peroxide. These may be used individually or in combination of two or more. Among these, dialkyl peroxides are preferred from the viewpoint of reactivity with fluorine-containing copolymers. There are no particular restrictions on the dialkyl peroxides, and examples include 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxyperoxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexine, tert-butylperoxymaleic acid, and tert-butylperoxysopropyl carbonate. These may be used individually or in combination of two or more. Among these, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane is preferred from the viewpoint of reactivity with fluorine-containing copolymers.

[0064] When a fluorine-containing copolymer-containing composition contains a crosslinking agent, there are no particular restrictions on the amount of crosslinking agent, but it is preferably 0.3 to 10.0 parts by mass, more preferably 0.3 to 5.0 parts by mass, and most preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of the fluorine-containing copolymer. If the amount is above the lower limit, it becomes easier to shorten the reaction time with the fluorine-containing copolymer, and if it is below the upper limit, it becomes easier to ensure sufficient flow time during molding.

[0065] -Specific Polymerizable Compounds- Specific polymerizable compounds are compounds having two or more polymerizable unsaturated bonds in one molecule and are used as crosslinking aids to improve the crosslinking reactivity of fluorine-containing copolymers. Fluorine-containing copolymer-containing compositions may or may not contain specific polymerizable compounds. Among these, it is preferable to include them from the viewpoint of improving the crosslinking efficiency of the fluorine-containing copolymer-containing composition. There are no particular restrictions on the polymerizable unsaturated bonds, and examples include carbon-carbon double bonds (C=C), carbon-carbon triple bonds (C≡C), etc. These may be used individually or in combination of two or more. Among these, carbon-carbon double bonds (C=C) are preferred from the viewpoint of superior crosslinking reactivity. There are no particular restrictions on the number of polymerizable unsaturated bonds in the specific polymerizable compound as long as there are two or more, but preferably 2 to 6, more preferably 2 or 3, and particularly preferably 2. If the number is above the lower limit, it becomes easier to react with fluorine-containing copolymers, and if it is below the upper limit, it becomes easier to control the reaction with fluorine-containing copolymers. While there are no particular restrictions on the specific polymerizable compound, it is preferable that the compound has two or more vinyl or allyl groups, from the viewpoint of superior crosslinking reactivity and lower compression set at high temperatures. Furthermore, while there are no particular restrictions on the specific polymerizable compound, it is preferable that it has a fluorine atom, from the viewpoint of superior weather resistance and chemical resistance of the crosslinked rubber article.

[0066] There are no particular restrictions on the specific polymerizable compound, and examples include the compound represented by the following formula (7), triallyl cyanurate, triallyl isocyanurate, trimethyl isocyanurate, etc. These may be used individually or in combination of two or more. Among these, the compound represented by the following formula (7) and triallyl isocyanurate are preferred from the viewpoint of excellent crosslinking reactivity.

[0067] Equation (7) is as follows: (CR ６１ R ６２ =CR ６３ ) ２ R ６４ Formula (7) In formula (7), R６１ , R ６２ , and R ６３ Each independently represents a hydrogen atom, a fluorine atom, a C1-C5 alkyl group, or a C1-C5 fluoroalkyl group, and R ６４ This represents a divalent fluorohydrocarbon group having 1 to 18 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of the fluorohydrocarbon group. Multiple R ６１ , multiple R ６２ , and multiple R ６３ These elements may be identical to each other, or they may be different.

[0068] R ６１ , R ６２ , and R ６３ The alkyl or fluoroalkyl group in R may be linear or branched. Of these, linear is preferred. ６１ , R ６２ , and R ６３ The number of carbon atoms in the alkyl or fluoroalkyl group is not particularly limited as long as it is between 1 and 5, but is preferably between 1 and 3, more preferably 1 or 2. ６１ , R ６２ , and R ６３ There are no particular restrictions, but from the viewpoint of superior crosslinking reactivity, it is preferable that all atoms be hydrogen atoms.

[0069] R ６４ There are no particular restrictions on the fluorohydrocarbon group in this, but from the viewpoint of having superior heat resistance of the crosslinked rubber article, a perfluorohydrocarbon group is preferred. ６４ The chain may be linear, branched, or cyclic. Among these, linear and branched chains are preferred, with linear being more preferred. ６４ The number of carbon atoms is not particularly limited as long as it is between 1 and 18, but is preferably 2 to 8, more preferably 3 to 7. ６４ If it has an etheric oxygen atom, R ６４ There are no particular restrictions on the number of etheric oxygen atoms in R, but it is preferably 1 to 6, more preferably 1 to 3, and most preferably 1 or 2.６４ If it has an etheric oxygen atom, there are no particular restrictions on the etheric oxygen atom, but preferably R ６４ It is present at the terminal end. There are no particular restrictions on the compound represented by formula (7), but it is preferably the compound represented by formula (2) above, and more preferably the compounds represented by formulas (3) and (4). There are no particular restrictions on the compounds represented by formulas (3) and (4), but they are preferably C3DVE, C4DVE, CH ２ =CH(CF ２ ) ２ CH=CH ２ ,CH ２ =CH(CF ２ ) ４ CH=CH ２ Furthermore, C6DV is preferred from the viewpoint that the compression set after long-term heating of the cross-linked rubber article is smaller.

[0070] When a fluorine-containing copolymer-containing composition contains a specific polymerizable compound, there are no particular restrictions on the amount of the specific polymerizable compound, but it is preferably 0.03 to 5.0 parts by mass, more preferably 0.1 to 4.0 parts by mass, and particularly preferably 0.3 to 3.0 parts by mass, per 100 parts by mass of the fluorine-containing copolymer. If the amount is above the lower limit, the compression set of the crosslinked rubber article tends to be smaller, and if it is below the upper limit, the crosslinking reactivity tends to be superior.

[0071] -Other Components- The fluorine-containing copolymer-containing composition may or may not contain other components as long as the effects of the present invention are not impaired. There are no particular limitations on the other components, and examples include acid acceptors such as fatty acid esters, fatty acid metal salts (sodium stearate, calcium stearate, etc.), and divalent metal oxides (magnesium oxide, calcium oxide, zinc oxide, lead oxide, etc.); fillers and reinforcing materials such as carbon black, barium sulfate, calcium metasilicate, calcium carbonate, titanium dioxide, silicon dioxide, aromatic polyesters, polyamide-imides and thermoplastic polyimides, clay, talc, etc.; scorch retarders such as phenolic hydroxyl group-containing compounds (bisphenol A, etc.), quinones (hydroquinone, etc.), and α-methylstyrene dimers (2,4-di(3-isopropylphenyl)-4-methyl-1-pentene, etc.); and crown ethers such as 18-crown-6. These may be used individually or in combination of two or more.

[0072] When a fluorine-containing copolymer-containing composition contains other components, there are no particular restrictions on the total content of the other components, but preferably it is more than 0.01 parts by mass and 30 parts by mass or less, more preferably 0.05 to 25 parts by mass, and particularly preferably 0.1 to 15 parts by mass, per 100 parts by mass of the fluorine-containing copolymer. If it is above the lower limit, the mechanical strength of the crosslinked rubber article tends to improve, and if it is below the upper limit, it becomes easier to control the flow during molding.

[0073] (Method for producing a fluorine-containing copolymer composition) There are no particular restrictions on the method for producing a fluorine-containing copolymer composition, and examples include mixing the above components. There are no particular restrictions on the mixing method, and it can be carried out using rubber mixing equipment such as a two-roll mixer, kneader, Banbury mixer, or extruder. These may be used individually or in combination of two or more. After obtaining a fluorine-containing copolymer composition by mixing the above components, the fluorine-containing copolymer composition may or may not be molded. There are no particular restrictions on the molding method of the fluorine-containing copolymer composition, and examples include compression molding, injection molding, extrusion molding, calendering, and molding by dissolving in a solvent and dipping or coating onto a substrate, etc. These may be used individually or in combination of two or more.

[0074] <Solids Derived from Release Agent> The solids derived from the release agent adhering to the surface of the crosslinked rubber article in this embodiment refer to the release agent after some of the solvent and compounds have been removed during the crosslinked rubber article manufacturing process (crosslinking reaction, etc.). The contact angle of the solids derived from the release agent adhering to the surface of the crosslinked rubber article is determined by dissolving 1 g of the solids in 99 g of solvent (ethanol) to make a test release agent solution, wiping the surface of the crosslinked rubber article with a cloth (Kimtex, manufactured by Nippon Paper Crecia Co., Ltd.) impregnated with ethanol, drying at room temperature to make a test crosslinked rubber sheet, and then determining the contact angle by the method described in the examples. In this specification, "release agent" means a liquid mixture unless otherwise specified.

[0075] There are no particular restrictions on the content of solids derived from the mold release agent adhering to the surface of a crosslinked rubber article relative to 100% by mass of the crosslinked rubber article, but it is preferably 10 to 1000 ppm by mass, more preferably 100 to 1000 ppm by mass, and particularly preferably 500 to 1000 ppm by mass. If it is above the lower limit, the mold release properties tend to be better, and if it is below the upper limit, the occurrence of bleeding tends to be suppressed.

[0076] (Release Agent) The release agent has a contact angle of 30° or more with the crosslinked rubber described above. As long as the contact angle between the crosslinked rubber and the release agent is 30° or more, there are no particular restrictions, and it is preferably 31 to 120°, more preferably 35 to 100°, and most preferably 36 to 98°. If it is above the lower limit, it becomes easier to suppress the transfer of the release agent, and if it is below the upper limit, it becomes easier to achieve both bleeding and release properties. The contact angle between the crosslinked rubber and the release agent is determined by the method described in the examples using a test crosslinked rubber sheet made without the release agent and a test release agent solution from which the volatile components of the release agent have been evaporated.

[0077] There are no particular restrictions on the release agent; for example, silicone-based release agents and fluorine-based release agents can be used. These may be used individually or in combination of two or more. Among these, fluorine-based release agents are preferred from the viewpoint of heat resistance and prevention of contamination of semiconductor manufacturing equipment. The release agent can be identified by dissolving the solid component in hexafluorobenzene at 2.0% by mass, forming a film on an ETFE film by drop casting, and performing XPS (X-ray Photoelectron Spectroscopy) measurement to detect the XPS spectra of fluorine and silicon. The solid component used in the above identification method can be prepared by wiping the surface of a crosslinked rubber article with a cloth impregnated with ethanol (Kimtex, manufactured by Nippon Paper Crecia Co., Ltd.), immersing the cloth in ethanol for 24 hours, and then evaporating the ethanol from the solution after immersion.

[0078] -Silicone-based mold release agent- There are no particular restrictions on the silicone-based mold release agent that contains solid components derived from the mold release agent that adhere to the surface of the cross-linked rubber. Examples include silicone oil and polysilsesquioxane. These may be used individually or in combination of two or more. Among these, silicone oil is preferred from the viewpoint of having high affinity with solvents and being able to reduce the amount used.

[0079] --Silicone Oil-- There are no particular restrictions on the silicone oil used; examples include dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, and modified silicone oil. These may be used individually or in combination of two or more. Among these, dimethyl silicone oil is preferred from the viewpoint of achieving both release properties and heat resistance.

[0080] There are no particular restrictions on the modified silicone oil. For example, a silicone oil in which at least a portion of the methyl groups of dimethyl silicone oil are substituted with one or more groups selected from the group consisting of polyoxyalkylene groups, long-chain alkyl groups, fluoroalkyl groups, chlorophenyl groups, amino groups, amino group-containing alkyl groups, epoxy groups, epoxy group-containing alkyl groups, mercapto groups, mercapto-containing alkyl groups, carboxyl groups, carboxyl group-containing groups, higher fatty acid residues, hydroxyl groups, and vinyl groups. These may be used individually or in combination of two or more. Among these, dimethyl silicone oil in which at least a portion of the methyl groups are substituted with hydroxyl groups is preferred from the viewpoint of affinity with molds.

[0081] There are no particular restrictions on the kinematic viscosity of the silicone oil at 25°C, but from the viewpoint of release effect and emulsion stability, it is preferably 50 to 100,000 mm. ２ / s, more preferably 100 to 10,000 mm ２ / s, particularly preferably 100 to 7,500 mm ２ The value is / s. If it is above the lower limit, the release properties tend to be good, and if it is below the upper limit, a stable silicone oil tends to be obtained. The kinematic viscosity of the silicone oil at 25°C is determined by the measurement method described in the examples.

[0082] There are no particular restrictions on the solvent included in the silicone-based mold release agent, but it is preferable that its boiling point at atmospheric pressure is above room temperature, specifically 25°C or higher. Examples of solvents included in the silicone-based mold release agent include volatile silicones, water, petroleum-based solvents, waxes, and hydrocarbon-based solvents. These may be used individually or in combination of two or more.

[0083] There are no particular restrictions on the volatile silicone, and examples include hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, and dodecamethylpentasiloxane. These may be used individually or in combination of two or more. Among these, dodecamethylpentasiloxane is preferred from the viewpoint of mold release properties and volatility in secondary crosslinking.

[0084] There are no particular restrictions on the petroleum-based solvents, and examples include petroleum ether, petroleum benzine, petroleum naphtha, ligroin, industrial gasoline, kerosene, and solvent naphtha, which have a boiling point in the range of 30 to 300°C. These may be used individually or in combination of two or more. Among these, petroleum ether, petroleum benzine, petroleum naphtha, ligroin, and solvent naphtha are preferred from the viewpoint of their excellent dissolution of silicone oil.

[0085] There are no particular restrictions on the types of waxes used; examples include plant-based waxes, animal-based waxes, mineral-based waxes, synthetic waxes, and wax-like substances. These may be used individually or in combination of two or more types. There are no particular restrictions on plant-based waxes; examples include carnauba wax, candelilla wax, rice wax, and wood wax. These may be used individually or in combination of two or more types. There are no particular restrictions on animal-based waxes; examples include beeswax, whale wax, lanolin, lanolin derivatives, beef tallow, and lard. These may be used individually or in combination of two or more types. There are no particular restrictions on mineral-based waxes; examples include paraffin, petrolatum, ozokerite, ceresin, and microcrystalline wax. These may be used individually or in combination of two or more types. There are no particular restrictions on the synthetic wax, and examples include polyethylene wax, polypropylene wax, α-olefin wax, esters of synthetic fatty acids and higher alcohols, synthetic fatty acid glycerides, oxidized paraffin, oxidized microcrystalline wax, and copolymers of olefins with one or more selected from the group consisting of maleic anhydride, acrylic acid, and vinyl acetate. These may be used individually or in combination of two or more.

[0086] There are no particular restrictions on the hydrocarbon solvents, and examples include aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents. These may be used individually or in combination of two or more. There are no particular restrictions on the aliphatic hydrocarbon solvents, and examples include linear aliphatic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, undecane, and dodecane; branched aliphatic hydrocarbons such as 2-methylbutane, 2-methylpentane (isohexane), 2,3-dimethylbutane, 2,2-dimethylbutane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane (isooctane), and 2,2,5-trimethylhexane; and alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, methylcyclopentane, ethylcyclohexane, p-menthane, and decalin. These may be used individually or in combination of two or more. There are no particular restrictions on the aromatic hydrocarbon solvents, and examples include benzene, toluene, p-xylene, o-xylene, m-xylene, ethylbenzene, cumene, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, p-cymene, mesitylene, tetralin, cyclohexylbenzene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, pentylbenzene, dipentylbenzene, dodecylbenzene, etc. These may be used individually or in combination of two or more.

[0087] -Fluorine-based release agents- There are no particular restrictions on the solid components derived from the release agent that are contained in the fluorine-based release agent and adhere to the surface of the cross-linked rubber. Examples include fluorine-based polymers, fluorine-based surfactants, fluorine-containing organophosphorus compounds, and fluorine compounds containing polytetrafluoroethylene. These may be used individually or in combination of two or more. Among these, fluorine-based polymers, fluorine-based surfactants, and fluorine-containing organophosphorus compounds are preferred from the viewpoint of ensuring release properties with a small amount of solid content, and fluorine-based polymers are more preferred from the viewpoint of obtaining good release properties at low concentrations.

[0088] --Fluorine-based polymers-- As long as the fluorine-based polymer contains fluorine atoms and has a resin adhesion prevention effect, there are no particular limitations. Examples include polyvinylidene fluoride, polytetrafluoroethylene, tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymers, tetrafluoroethylene / ethylene copolymers, tetrafluoroethylene / propylene copolymers, tetrafluoroethylene / hexafluoropropylene copolymers, vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymers, fluorine-containing acrylate polymers, polymers having a fluorine-containing aliphatic ring structure in the main chain, polyvinyl fluoride, polychlorotrifluoroethylene, chlorotrifluoroethylene / ethylene copolymers, chlorotrifluoroethylene / hydrocarbon alkenyl ether copolymers, vinylidene fluoride / hexafluoropropylene copolymers, fluorine-containing cyclic polymers, etc. These may be used individually or in combination of two or more. Among these, fluorine-containing acrylate polymers are preferred from the viewpoint of reducing bleeding after secondary crosslinking at low concentrations. Commercially available fluorine-based polymers include: products from Sumitomo 3M Co., Ltd. such as Florard FC-430 and FC-431; products from AGC Inc. such as Surflon S-382; products from Tochem Products Co., Ltd. such as EFTOP EF-122A, 122B, 122C, EF-121, EF-126, EF-127, and MF-100; products from OMNOVA such as PF-636, PF-6320, PF-656, and PF-6520; products from Neos Co., Ltd. such as Futergent 250, Futergent 251, DFX-18, and Freelys 6112; and Unidyne. Examples include products from Daikin Industries, Ltd. such as "DS-401, DS-403, DS-451, R-2020, M-2020, R-3833, M-3833, and Daiel Latex DPA-382"; products from DIC Corporation such as Megafac "171, 172, 173, 178K, 178A, 780F, F-171, F-172, F-179A" and Defensor MCF-300; products from Fine Chemical Japan Co., Ltd. such as FC-109; and products from Harves Co., Ltd. such as Durasurf HD-1100 series and Durasurf HD-2100 series.These may be used individually or in combination of two or more types.

[0089] There are no particular restrictions on the fluorine-containing acrylate polymer, and examples include the fluorine-containing acrylate polymer described in International Publication No. 2020 / 040249. There are no particular restrictions on the specific compounds of the fluorine-containing acrylate polymer, and examples include AsahiGuard E-SERIES™ (manufactured by AGC Inc.), such as AG-E061, AG-E081, AG-E400, AG-E100, AG-E090, and AG-E550D; and Freely 6112 (manufactured by Neos Co., Ltd.). These may be used individually or in combination of two or more. Among these, AG-E400 and Freely 6112 are preferred from the viewpoint of heat resistance.

[0090] The fluorine-based polymer was extracted from the mold release agent with methanol and separated by gas chromatography. １ H and １９ It can be identified by F-nuclear magnetic resonance (NMR) analysis.

[0091] --Fluorine-based surfactants-- There are no particular restrictions on fluorine-based surfactants, and examples include anionic fluorine-based surfactants, cationic fluorine-based surfactants, and nonionic fluorine-based surfactants. These may be used individually or in combination of two or more.

[0092] There are no particular restrictions on the nonionic fluorinated surfactant; examples include polyoxyethylene alkyl ethers and sorbitan alkyl esters. These may be used individually or in combination of two or more. There are no particular restrictions on the polyoxyethylene alkyl ether; examples include polyoxyethylene lauryl ether. These may be used individually or in combination of two or more.

[0093] There are no particular restrictions on the anionic fluorinated surfactant, and examples include alkyl sulfates, alkyl sulfonates, and alkyl phosphate esters. These may be used individually or in combination of two or more. There are no particular restrictions on the alkyl sulfate ester, and examples include sodium alkyl sulfate.

[0094] There are no particular restrictions on the cationic fluorine-based surfactant, and examples include quaternary ammonium salts and alkylamine salts. These may be used individually or in combination of two or more. There are no particular restrictions on the quaternary ammonium salt, and examples include lauryltrimethylammonium chloride. These may be used individually or in combination of two or more.

[0095] --Fluorine-containing organophosphorus compounds-- There are no particular restrictions on the fluorine-containing organophosphorus compounds, and examples include perfluoroalkyl phosphorous acid, perfluoroalkyl phosphate salts, and perfluoroalkyl phosphate esters. These may be used individually or in combination of two or more. Among these, perfluoroalkyl phosphorous acid is preferred from the viewpoint of compatibility with the solvent.

[0096] --Fluorine compounds containing polytetrafluoroethylene-- There are no particular restrictions on the fluorine compounds containing polytetrafluoroethylene. Examples include polymers (PTFE) obtained by polymerizing tetrafluoroethylene according to conventionally known methods, and polymers obtained by polymerizing monomer compositions mainly composed of tetrafluoroethylene according to conventionally known methods. These may be used individually or in combination of two or more. Among these, PTFE is preferred from the viewpoint of availability.

[0097] There are no particular restrictions on the solvents included in the fluorine-based release agent. Examples include trifluorotrichloroethane, tetrachlorodifluoroethane, acetone, chloroform, isopropyl alcohol, pentane, hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, petroleum ether, tetrahydrofuran, 1,4-dioxane, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, and water. These may be used individually or in combination of two or more. Among these, trifluorotrichloroethane, tetrachlorodifluoroethane, and water are preferred from the viewpoint of heat resistance and dispersibility of fluorine compounds.

[0098] There are no particular restrictions on the content of solids derived from the mold release agent that adhere to the surface of the crosslinked rubber in 100% by mass of the mold release agent, but it is preferably 0.1 to 50% by mass, more preferably 0.1 to 20% by mass, and most preferably 0.1 to 10% by mass. If it is above the lower limit, mold release performance tends to be good, and if it is below the upper limit, both transferability (gloss difference) and mold release performance tend to be good. When the mold release agent is a fluorine-based mold release agent containing a fluorine-based polymer, there are no particular restrictions on the content of the fluorine-based polymer in 100% by mass of the fluorine-based mold release agent, but it is preferably 5% by mass or less, more preferably 0.1 to 5.0% by mass, and most preferably 0.1 to 3.0% by mass. If it is above the lower limit, mold release becomes easier, and if it is below the upper limit, bleeding tends to be reduced. In this specification, "transferability (gloss difference)" means the value obtained by the calculation method and measurement method described in the examples. There are no particular restrictions on the transferability (gloss difference), but it is preferably 0.1 to 9.9, more preferably 0.1 to 8.0, and especially preferably 0.1 to 5.0. If it is above the lower limit, it becomes easier to release from the mold, and if it is below the upper limit, it becomes easier to reduce bleeding.

[0099] There are no particular restrictions on the solvent content in 100% by mass of the release agent, but it is preferably 50.0 to 99.9% by mass, more preferably 80.0 to 99.9% by mass, and particularly preferably 90.0 to 99.9% by mass. If the solvent content in the release agent is above the lower limit, the release agent can be applied uniformly to the mold, while if it is below the upper limit, the amount of solids contained in the release agent can be reduced, thereby reducing bleeding of the crosslinked rubber article.

[0100] [Method for Manufacturing Crosslinked Rubber Articles] The method for manufacturing crosslinked rubber articles of this embodiment is a method for manufacturing crosslinked rubber articles of this embodiment, comprising applying the above-mentioned release agent to the surface of a fluorine-containing copolymer-containing composition containing the above-mentioned fluorine-containing copolymer, and crosslinking the fluorine-containing copolymer-containing composition to which the release agent has been applied. The crosslinked rubber article of this embodiment comprises a crosslinked rubber which is a crosslinked product of a fluorine-containing copolymer-containing composition containing the above-mentioned fluorine-containing copolymer, and solid components derived from the release agent attached to the surface of the crosslinked rubber, wherein the crosslinked rubber has a contact angle of 30° or more with the release agent.

[0101] There are no particular limitations on the method of applying a release agent to the surface of a fluorine-containing copolymer-containing composition. For example, one method is to directly apply the release agent to the fluorine-containing copolymer-containing composition (Method 1); another method is to apply the release agent to equipment used to crosslink the fluorine-containing copolymer-containing composition, and then apply the release agent when installing the fluorine-containing copolymer-containing composition on the equipment (i.e., when installing the fluorine-containing copolymer-containing composition on the surface of the equipment to which the release agent has been applied) (Method 2). These methods may be used individually or in combination of two or more. Among these, Method 2 is preferred.

[0102] Methods for crosslinking a fluorine-containing copolymer-containing composition include crosslinking by heating; crosslinking by irradiation with radiation such as electron beams or ultraviolet rays; and the like. Among these, crosslinking by heating is preferred from the viewpoint of moldability. There are no particular restrictions on the above-mentioned crosslinking by heating, and examples include hot press crosslinking, steam crosslinking, and hot air crosslinking. These may be used individually or in combination of two or more. These methods should be appropriately selected considering the shape and application of the fluorine-containing copolymer-containing composition. There are no particular restrictions on the heating conditions, but from the viewpoint of surface smoothness of the crosslinked rubber article, heating at 100 to 400°C for 1 second to 24 hours is preferred.

[0103] A crosslinked rubber article obtained by heating a fluorine-containing copolymer-containing composition (primary crosslinking) may be further heated (secondary crosslinking). By performing secondary crosslinking, the mechanical properties, compression set, and other properties of the crosslinked rubber article can be stabilized or improved. When performing primary and secondary crosslinking, there are no particular restrictions on the heating temperature for primary crosslinking, but from the viewpoint of dispersibility of the mold release agent, it is preferably 100 to 400°C, more preferably 120 to 300°C, and particularly preferably 140 to 200°C. When performing primary and secondary crosslinking, there are no particular restrictions on the heating temperature for secondary crosslinking, but from the viewpoint of heat resistance of the crosslinked rubber article, it is preferably 50 to 400°C, more preferably 70 to 380°C, and particularly preferably 90 to 350°C. When performing primary and secondary crosslinking, there are no particular restrictions on the heating time for primary crosslinking, but from the viewpoint of dimensional stability of the crosslinked rubber article, it is preferably 1 second to 10 hours, more preferably 1 minute to 6 hours, and particularly preferably 10 minutes to 5 hours. When performing primary and secondary crosslinking, there are no particular restrictions on the heating time for secondary crosslinking, but from the viewpoint of stabilizing the physical properties of the crosslinked rubber article, it is preferably 1 minute to 48 hours, more preferably 10 minutes to 32 hours, and particularly preferably 1 hour to 30 hours. There are no particular restrictions on the heating conditions when performing secondary crosslinking, but it is preferably heated at 50 to 400°C for 1 minute to 24 hours.

[0104] The present invention will be described in detail below with reference to examples. Examples 1, 3-4, 8-11, 13, and 15 are examples, and examples 2, 5-7, 12, 14, and 16 are comparative examples. However, the present invention is not limited to these examples.

[0105] [Measurement of the composition of fluorine-containing copolymers] １９ The content (mol%) of each unit in the fluorine-containing copolymer was calculated by F-nuclear magnetic resonance (NMR) analysis. However, the content of propylene units was calculated as follows: １ H and １３ The iodine content in the fluorine-containing copolymer was calculated from 13C nuclear magnetic resonance (NMR) analysis. Furthermore, the iodine atom content in the fluorine-containing copolymer was calculated using a combination of an automated sample combustion system for ion chromatography fluffs (Mitsubishi Chemical Analytec Co., Ltd., AQF-100 model) and an ion chromatograph. The content (mol%) of each unit in other fluorine-containing copolymers was determined by melt NMR analysis and... １９ The content was calculated by F-nuclear magnetic resonance (NMR) analysis. However, the NAH unit content was calculated by the following infrared absorption spectrum analysis. -Infrared Absorption Spectrum Analysis- A 200 μm film was obtained by press molding another fluorine-containing copolymer. In the infrared absorption spectrum, the absorption peak for NAH-based units in the other fluorine-containing copolymer was 1778 cm⁻¹. －１ It appears there. The absorbance of the absorption peak was measured, and the molar extinction coefficient of NAH was 20810 mol. －１ ・l・cm －１ The proportion of NAH units in other fluorine-containing copolymers was determined using this method.

[0106] [Production of fluorine-containing copolymers] Fluorine-containing copolymers 1 and 2 were produced as follows.

[0107] (Fluorine-containing copolymer 1) After degassing a 20 L stainless steel pressure reactor equipped with anchor blades, 7.2 L of ultrapure water and C emulsifier are added. ２ F ５ OCF ２ CF ２ OCF ２ COONH ４880 g of a 30% by mass solution of [substance name], 7.3 g of 8CNVE, and 15.9 g of a 5% by mass aqueous solution of disodium hydrogen phosphate dodecahydrate were charged, and the gas phase was purged with nitrogen. While stirring at a speed of 375 rpm using an anchor blade, 137 g of TFE and 635 g of PMVE were injected into the container under pressure, and the internal temperature was raised to 80°C. The reactor internal pressure was 0.90 MPa [gauge]. 28 mL of a 3% by mass aqueous solution of ammonium persulfate (APS) was added, and polymerization was started. The initial addition ratio of monomers, expressed as a molar ratio, was TFE:PMVE:8CNVE = 26.30:73.30:0.40. After polymerization started, monomers were injected under pressure as polymerization progressed, as follows. When the reactor pressure dropped to 0.89 MPa [gauge], TFE was injected, and the reactor pressure was increased to 0.90 MPa [gauge]. This was repeated, and each time 119.3 g of TFE was injected, 3.7 g of 8CNVE, 74 g of PMVE, and 3.7 g of 8CNVE were injected in that order. When the polymerization rate began to decrease, a 3% by mass aqueous solution of APS was added as needed. The total amount of 3% by mass aqueous solution of APS added after the start of polymerization was 35 mL. When the cycle in which the total amount of added TFE reached 1073.7 g was completed, 119.3 g of TFE was injected. When the total amount of subsequently added TFE reached 1193 g, the addition of the subsequently added monomers was stopped, the reactor temperature was cooled to 10°C, the polymerization reaction was stopped, and a latex containing a fluorine-containing copolymer was obtained. Furthermore, the total added mass of each monomer was 1193 g for TFE, 666 g for PMVE, and 66.6 g for 8CNVE. Converting this to a molar ratio, the ratio was TFE:PMVE:8CNVE = 74.00:25.00:1.00. Nitric acid (manufactured by Kanto Chemical Co., Ltd., special grade) was dissolved in ultrapure water to prepare a 3% by mass aqueous solution of nitric acid. Latex was added to the nitric acid aqueous solution in a TFE / perfluoro(alkyl vinyl ether) copolymer (PFA) container to agglomerate the fluorine-containing copolymer. The amount of nitric acid aqueous solution was 150 parts by mass for every 100 parts by mass of fluorine-containing copolymer in the latex. The agglomerated fluorine-containing copolymer was recovered by filtration and added to ultrapure water in a PFA container, and washed by stirring at 200 rpm for 30 minutes. The amount of ultrapure water was 100 parts by mass for every 100 parts by mass of fluorine-containing copolymer.The above washing process was repeated 10 times. The washed fluorine-containing copolymer was recovered by filtration and dried under reduced pressure at 50°C and 10 kPa to obtain fluorine-containing copolymer 1. The molar ratio of each unit in fluorine-containing copolymer 1 was TFE units:PMVE units:8CNVE units = 70.90:28.60:0.50.

[0108] (Fluorine-containing copolymer 2) After degassing a 20 L stainless steel pressure reactor equipped with anchor blades, 8.2 L of ultrapure water, C ２ F ５ OCF ２ CF ２ OCF ２ COONH ４733 g of a 30% by mass solution of [substance name], 10.0 g of C3DVE, and 15.9 g of a 5% by mass aqueous solution of disodium hydrogen phosphate dodecahydrate were charged, and the gas phase was purged with nitrogen. While stirring at a speed of 375 rpm using an anchor blade, 198 g of TFE and 454 g of PMVE were injected into the container under pressure once the internal temperature reached 80°C. The reactor internal pressure was 0.90 MPa [gauge]. 40 mL of a 1% by mass aqueous solution of ammonium persulfate (APS) was added to start polymerization. The molar ratio of the monomers injected under pressure before the start of polymerization (hereinafter also referred to as "initial monomers") was TFE:PMVE:C3DVE = 41.74:57.64:0.61. As polymerization progressed, when the reactor pressure decreased to 0.89 MPa [gauge], TFE was injected to raise the reactor pressure to 0.90 MPa [gauge]. This was repeated, and 62 g of PMVE was injected each time 80 g of TFE was injected. In addition, 7.0 g of 1,4-diiodoperfluorobutane was injected into the reactor from an ampoule tube along with 50 mL of ultrapure water when 60 g of TFE had been injected. When the total mass of TFE added reached 1200 g, the addition of monomers injected after the start of polymerization (hereinafter also referred to as "post-added monomers") was stopped, the reactor temperature was cooled to 10°C, the polymerization reaction was stopped, and a latex containing a fluorine-containing copolymer was obtained. Furthermore, the total added monomers were 1200 g of TFE and 868 g of PMVE, which, when converted to a molar ratio, was TFE:PMVE = 68:32. Nitric acid (manufactured by Kanto Chemical Co., Ltd., special grade) was dissolved in ultrapure water to prepare a 3% by mass aqueous solution of nitric acid. Latex was added to the nitric acid aqueous solution in a TFE / perfluoro(alkyl vinyl ether) copolymer (PFA) container to agglomerate the fluorine-containing copolymer. The amount of nitric acid aqueous solution was 150 parts by mass for every 100 parts by mass of fluorine-containing copolymer in the latex. The agglomerated fluorine-containing copolymer was recovered by filtration and added to ultrapure water in a PFA container, and washed by stirring at 200 rpm for 30 minutes. The amount of ultrapure water was 100 parts by mass for every 100 parts by mass of fluorine-containing copolymer. The above washing was repeated 10 times. The washed fluorine-containing copolymer was recovered by filtration and dried under reduced pressure at 50°C and 10 kPa to obtain fluorine-containing copolymer 2.The molar ratio of each unit in fluorine-containing copolymer 2 was TFE units:PMVE units:C3DVE units = 71.40:28.43:0.17. The iodine atom content was 0.10% by mass.

[0109] [Production of Fluorine-Containing Copolymer-Containing Compositions] Fluorine-containing copolymer-containing compositions 1 to 3 were produced as follows.

[0110] (Fluorine-containing copolymer-containing composition 1) 100 parts by mass of fluorine-containing copolymer 1 and 0.8 parts by mass of a crosslinking agent (BOAP: 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed and kneaded at 25°C for 10 minutes using two rolls to obtain fluorine-containing copolymer-containing composition 1.

[0111] (Fluorine-containing copolymer-containing composition 2) In the production of fluorine-containing copolymer-containing composition 1, fluorine-containing copolymer-containing composition 2 was obtained in the same manner as fluorine-containing copolymer-containing composition 1, except that 5 parts by mass of another fluorine-containing copolymer ("Fluorine-containing copolymer (X1-1)" in the Examples section of International Publication No. 2016 / 017801 (units based on NAH / TFE / PPVE = 0.10 / 97.90 / 2.00 (mol%), melting point 300°C, MFR 17.6 g / 10 min) was further prepared by grinding it with a jet mill (average particle size (volume-based cumulative 50% diameter (D50)) 2.5 μm)). The average particle size was determined by dispersing it in isopropyl alcohol using a laser diffraction / scattering particle size distribution analyzer (LMS-2000e, manufactured by Seishin Corporation) to prepare a dispersion (solid content concentration 0.5% by mass), and measuring the volume-based cumulative 50% diameter (D50).

[0112] (Fluorine-containing copolymer-containing composition 3) 100 parts by mass of fluorine-containing copolymer 2, 2.0 parts by mass of a specific polymerizable compound (TAIC, manufactured by Mitsubishi Chemical Corporation, triallyl isocyanurate), 1.0 part by mass of an organic peroxide (Perhexa 25B, manufactured by Nippon Oil & Fats Co., Ltd., 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.1 parts by mass of calcium stearate were mixed and kneaded at 25°C for 10 minutes using a two-roller to obtain fluorine copolymer composition 3.

[0113] [Examples 1-16] The cross-linked rubber articles of Examples 1-16 were obtained as follows.

[0114] (Example 1) Using a hydraulic press (model: SA-301 50T type, manufactured by Tester Sangyo Co., Ltd., ram diameter: 180 mm), a 9-cavity P-26 O-ring mold (standard specified in JIS B 2401:2012) was heated to 180°C. After confirming that the mold temperature reached 180°C using a contact thermometer (DT-510, manufactured by Hozan Co., Ltd.), the upper and lower molds were immediately opened, and release agent 1 (JIP122, silicone-based release agent, silicone oil: high viscosity dimethyl silicone, manufactured by Ichinen Chemicals Co., Ltd.) was evenly applied to the upper and lower molds. Then, fluorine-containing copolymer-containing composition 1 was placed in the lower mold, the upper mold was closed, and the O-ring was obtained by heating and pressing at 180°C for 20 minutes (primary crosslinking). The O-ring was then heated under the conditions shown below (secondary crosslinking). -Conditions for secondary crosslinking- The material was heated in an inert oven (DN411I, manufactured by Yamato Scientific Co., Ltd.) under a nitrogen atmosphere at 90°C for 2 hours, then the temperature was raised to 200°C over 2 hours and held at 200°C for 4 hours. Furthermore, the temperature was raised to 305°C over 2 hours and heated at 305°C for 13 hours to obtain the crosslinked rubber article of Example 1.

[0115] (Examples 2-10) Cross-linked rubber articles for Examples 2-10 were obtained in the same manner as in Example 1, except that the mold release agent was replaced with one of the mold release agents shown in Table 1.

[0116] (Example 11) In the same manner as in Example 1, except that composition 1 containing fluorine copolymer was replaced with composition 2 containing fluorine copolymer, and the secondary crosslinking conditions were changed to the conditions shown below, a crosslinked rubber article of Example 11 was obtained. - Secondary crosslinking conditions - In an inert oven (DN411I, manufactured by Yamato Scientific Co., Ltd.), the temperature was raised from 25°C to 200°C over 4 hours in an air atmosphere, held at 200°C for 16 hours, then raised to 310°C over 2 hours, and heated at 310°C for 12 hours to obtain the crosslinked rubber article of Example 11.

[0117] (Examples 12-14) The cross-linked rubber articles of Examples 12-14 were obtained in the same manner as in Example 11, except that the release agent was replaced with one of the release agents shown in Table 1.

[0118] (Example 15) In Example 8, the fluorine-containing copolymer-containing composition 1 was replaced with the fluorine-containing copolymer-containing composition 3, and the secondary crosslinking conditions were changed to the conditions shown below. The crosslinked rubber article of Example 15 was obtained in the same manner as in Example 8. -Secondary crosslinking conditions- The crosslinked rubber article of Example 15 was obtained by heating in an inert oven (DN411I, manufactured by Yamato Scientific Co., Ltd.) in an air atmosphere at 250°C for 4 hours.

[0119] (Example 16) The crosslinked rubber article of Example 16 was obtained in the same manner as in Example 15, except that the release agent was replaced with one of the release agents shown in Table 1.

[0120] The following is an overview of each component listed in Table 1, excluding the fluorine-containing copolymer composition: • Release agent 1: JIP122, silicone-based release agent, silicone oil: high viscosity (kinematic viscosity at 25°C: 5000 mm) ２ / s) Dimethyl silicone oil, manufactured by Ichinen Chemicals Co., Ltd. - Release agent 2; Free Release 50, fluorine-based release agent, fluorine-containing acrylate polymer, manufactured by Neos Co., Ltd. - Release agent 3; Sumimold F1 (PFOA-free), fluorine-based release agent, fluorine-containing organophosphorus compound, manufactured by Sumiko Lubricants Co., Ltd. - Release agent 4; Chemlease AF-7EZ, a mixture of fluorine-based release agent and silicone-based release agent, silicone oil, and fluorine-containing acrylate polymer (fluorine-based polymer), manufactured by ChemTrend Japan Co., Ltd. - Release Agent 5; GA-3000, fluorine-based release agent, fluorine-containing acrylate polymer, manufactured by Daikin Industries, Ltd. - Release Agent 6; GA-9750M, fluorine-based release agent, fluorine-containing acrylate polymer, manufactured by Daikin Industries, Ltd. - Release Agent 7; SumiMold FA (PFOA-free), fluorine-based release agent, fluorine-containing organophosphorus compound, manufactured by Sumiko Lubricants Co., Ltd. - Release Agent 8; FreeRelease 6112 diluted 500 times with water, fluorine-based release agent, fluorine-containing acrylate polymer, manufactured by Neos Co., Ltd. - Release Agent 9; JIP121, silicone-based release agent, silicone oil: low viscosity (kinematic viscosity at 25°C: 100 mm) ２ / s) Dimethyl silicone oil, manufactured by Ichinen Chemicals Co., Ltd. - Release agent 10; KING TSM6822, silicone-based release agent, modified silicone oil, manufactured by Momentive - Release agent 11; JIP637, fluorine-based release agent, fluorine compound containing polytetrafluoroethylene: polytetrafluoroethylene, manufactured by Ichinen Chemicals Co., Ltd. The kinematic viscosity of the silicone oil at 25°C was determined using a Cannon-Fenske viscometer in accordance with JIS Z 8803:2011 "Method for measuring the viscosity of liquids". Furthermore, in this specification, "high viscosity" means 1000 mm ２ It means that it is 500 mm² or higher, and "low viscosity" means 500 mm². ２ This means it is less than or equal to / s.

[0121] [Evaluation of Crosslinked Rubber Articles] The following various measurements were performed to evaluate the crosslinked rubber articles of Examples 1 to 16. The evaluation results are shown in Table 1.

[0122] (Contact Angle Measurement) The fluorine-containing copolymer composition prepared above was filled into a mold (material: S55C, with Cr plating), and without applying a release agent, it was heated and pressed at 180°C for 20 minutes to obtain a test crosslinked rubber sheet measuring 100 mm in length, 60 mm in width, and 1 mm in thickness. Next, the contents of the release agent were transferred to a vial, left at 23°C for 24 hours to allow volatile components to evaporate, and a test release agent solution was obtained. The contact angle (°) was measured using the test release agent solution and the test crosslinked rubber sheet. The contact angle (°) was measured by placing droplets of the test release agent solution at five locations on the surface of the test crosslinked rubber sheet, referring to JIS R 3257:1999 "Test Method for Wettability of Substrate Glass Surfaces," and measuring the contact angle (°) for each droplet using the drop method. The droplet size was approximately 2 μL / droplet. The solution was placed in a polyethylene syringe (all-plastic disposable syringe, 2 mL, manufactured by HENKE) fitted with a Teflon® coated (22G) syringe needle at the tip. After degassing to remove air bubbles from the measurement solution, the contact angle (°) was measured. The measurement was performed at 23°C under the following conditions. The contact angle (°) was the average of the five measured values. -Measurement Conditions- • Measurement device: Portable contact angle meter (PCA-1, manufactured by Kyowa Interface Science Co., Ltd.) • Contact angle analysis: Required • Change over time: None • Measurement interval: 1000 (ms) • Analysis method: Sessil drop • Analysis method: Standard • Three-state system: None • Fit interval specification: None • Endpoint spacing (dot): 30 • Waiting time until measurement: 100 (ms) • Algorithm: Automatic • Image mode: Frame • Automatic threshold level: 128 • Automatic droplet recognition: Yes • Droplet line (dot): 50, 50, 50, 50, 50, 50 • Curvature correction: None • Radius of curvature (μm): 1,000,000 • Control mode: Standard • Automatic droplet creation: Yes • Liquid volume control: Yes • Droplet creation volume: 2 μL • Tolerance mode: None • Stage control mode: 1 The contact angle of solid components derived from the mold release agent adhering to the surface of the cross-linked rubber article is determined by dissolving 1 g of the solid components in 99 g of solvent (ethanol) to create a test mold release agent solution, wiping the surface of the cross-linked rubber article with a cloth (Kimtex, manufactured by Nippon Paper Crecia Co., Ltd.) impregnated with ethanol, drying it at room temperature to obtain a test cross-linked rubber sheet, and then determining the contact angle using the measurement method described above.

[0123] (Transferability (Gloss Difference)) The fluorine copolymer-containing composition prepared above was filled into a mold (material: S55C, with Cr plating), a release agent was applied, and the mold was heated and pressed at 180°C for 20 minutes to obtain a test cross-linked rubber sheet measuring 100 mm in length, 60 mm in width, and 1 mm in thickness. The test cross-linked rubber sheet was measured at 60° specular gloss at 10 different locations using a gloss checker (IG-410, manufactured by Horiba, Ltd.) with the range set to 1 to 100, and the average value was taken as Gloss (release agent). Next, a test cross-linked rubber sheet measuring 100 mm in length, 60 mm in width, and 1 mm in thickness was obtained using the above fluorine copolymer-containing composition under the same conditions except that a release agent was not applied. Using the obtained test cross-linked rubber sheet, the 60° specular gloss at 10 locations was measured in the same manner as above, and the average value was taken as Gloss (none). The absolute value of the difference between Gloss (with release agent) and Gloss (without) was defined as the transferability (gloss difference).

[0124] (Bleeding) The condition of the cross-linked rubber articles (O-rings) after secondary cross-linking (presence or absence of bleeding) was visually inspected. The bleeding properties were evaluated according to the following criteria: If the number of cross-linked rubber articles in which bleeding was confirmed was 0 out of 9 (0 / 9), the bleeding properties can be said to be particularly excellent (bleeding is particularly reduced). If the number of cross-linked rubber articles in which bleeding was confirmed was 1 (1 / 9) to 2 (2 / 9) out of 9 (0 / 9)

[0125]

[0126] As can be seen from the results shown in Table 1, the cross-linked rubber articles of the present invention (Examples 1, 3-4, 8-11, 13, and 15) showed reduced bleeding compared to cross-linked rubber articles that are not part of the present invention (Examples 2, 5-7, 12, 14, and 16).

Claims

1. A crosslinked rubber article comprising a crosslinked rubber which is a crosslinked product of a fluorine-containing copolymer-containing composition containing a fluorine-containing copolymer, and solid components derived from a mold release agent adhering to the surface of the crosslinked rubber, wherein the crosslinked rubber has a contact angle of 30° or more with the mold release agent.

2. The crosslinked rubber article according to claim 1, wherein the fluorine-containing copolymer has units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), and the molar ratio of the units based on tetrafluoroethylene to the units based on perfluoro(alkyl vinyl ether) (tetrafluoroethylene / perfluoro(alkyl vinyl ether)) is 60 to 80 / 20 to 40.

3. The crosslinked rubber article according to claim 1, wherein the mold release agent is a silicone-based mold release agent.

4. The crosslinked rubber article according to claim 1, wherein the mold release agent is a fluorine-based mold release agent.

5. The crosslinked rubber article according to claim 3, wherein the silicone-based release agent comprises at least one selected from the group consisting of silicone oil and polysilsesquioxane.

6. The crosslinked rubber article according to claim 4, wherein the fluorine-based release agent comprises at least one selected from the group consisting of fluorine-based polymers, fluorine-based surfactants, fluorine-containing organophosphorus compounds, and fluorine compounds including polytetrafluoroethylene.

7. The crosslinked rubber article according to claim 6, wherein the content of the fluorine-based polymer in 100% by mass of the fluorine-based release agent is 5% by mass or less.

8. A method for producing a crosslinked rubber article according to any one of claims 1 to 7, comprising: applying the release agent to the surface of a fluorine copolymer-containing composition containing the fluorine copolymer; and crosslinking the fluorine copolymer-containing composition on which the release agent has been applied.

9. The method for producing a crosslinked rubber article according to claim 8, wherein the fluorine-containing copolymer has units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether), and the molar ratio of the units based on tetrafluoroethylene to the units based on perfluoro(alkyl vinyl ether) (tetrafluoroethylene / perfluoro(alkyl vinyl ether)) is 60 to 80 / 20 to 40.

10. The method for producing a crosslinked rubber article according to claim 8, wherein the mold release agent is a silicone-based mold release agent.

11. The method for producing a crosslinked rubber article according to claim 8, wherein the mold release agent is a fluorine-based mold release agent.

12. The method for producing a crosslinked rubber article according to claim 10, wherein the silicone-based mold release agent comprises at least one selected from the group consisting of silicone oil and polysilsesquioxane.

13. The method for producing a crosslinked rubber article according to claim 11, wherein the fluorine-based release agent comprises at least one selected from the group consisting of fluorine-based polymers, fluorine-based surfactants, fluorine-containing organophosphorus compounds, and fluorine compounds including polytetrafluoroethylene.

14. The method for producing a crosslinked rubber article according to claim 13, wherein the content of the fluorine-based polymer in 100% by mass of the fluorine-based release agent is 5% by mass or less.

15. The method for manufacturing a crosslinked rubber article according to claim 8, wherein the crosslinked rubber article obtained by the above crosslinking is subjected to secondary crosslinking under conditions of 50 to 400°C and 1 minute to 48 hours.

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