Fluorine-containing copolymer composition, crosslinked rubber article

Abstract

A fluorinated copolymer composition and a crosslinked rubber article with suppressed weight loss are provided. The fluorinated copolymer composition is capable of forming a crosslinked rubber article in which weight loss, which begins after a predetermined time under prolonged use in a plasma irradiation environment, is suppressed. A fluorinated copolymer composition comprises a fluorinated copolymer (A), a fluorinated copolymer (B), and a crosslinking agent. The fluorinated copolymer (A) has tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units. The fluorinated copolymer (B) is a different fluorinated copolymer from the fluorinated copolymer (A) and contains units based on monomers having at least one functional group selected from the group represented by carboxyl groups and formula (X), tetrafluoroethylene-based units, and perfluoro(alkyl vinyl ether)-based units, and has a particle size D90 of 4.0 μm or less.

Description

Technical Field

[0001] This invention relates to fluorinated copolymer compositions and crosslinked rubber articles. Background Technology

[0002] Crosslinked rubber articles, made by crosslinking fluorinated copolymers, are widely used in vehicles, ships, aircraft, conventional machinery and construction, due to their excellent heat resistance, chemical resistance, oil resistance and weather resistance, as sealing materials (such as O-rings, gaskets, oil seals and liners) and cushioning materials.

[0003] Patent Document 1 discloses a composition comprising a specific fluorinated copolymer as a method for manufacturing a composition used in cross-linked rubber articles.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2021 / 210502 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In recent years, there has been a demand for improved performance of cross-linked rubber articles in various fields. Specifically, there is a need for fluorinated copolymer compositions that can suppress weight loss that begins after a specified time when used for a long period of time under plasma irradiation.

[0009] In response to such requirements, the inventors evaluated a cross-linked rubber article formed using the fluorinated copolymer composition described in Patent Document 1 and found that it was difficult to suppress the weight loss that began after the specified time.

[0010] The objective of this invention is to provide a fluorinated copolymer composition and a cross-linked rubber article, wherein the aforementioned fluorinated copolymer composition is capable of forming a cross-linked rubber article in which weight loss, which begins after a predetermined time when used for an extended period under plasma irradiation, is suppressed.

[0011] Solution for solving the problem

[0012] The inventors conducted in-depth research and found that the above-mentioned problems can be solved by the following configuration. [1]

[0014] A fluorinated copolymer composition comprising a fluorinated copolymer (A), a fluorinated copolymer (B), and a crosslinking agent.

[0015] The aforementioned fluorinated copolymer (A) has tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units.

[0016] The aforementioned fluorinated copolymer (B) is a fluorinated copolymer different from the aforementioned fluorinated copolymer (A), and contains units based on monomers having at least one functional group selected from the group represented by carboxyl groups and formula (X), units based on tetrafluoroethylene, and units based on perfluorinated (alkyl vinyl ethers), and has a particle size D90 of 4.0 μm or less, formula (X) *-CO-O-CO-*

[0017] In equation (X), * represents the bonding position. [2]

[0019] According to the fluorinated copolymer composition described in [1], wherein the fluorinated copolymer (A) further contains units having nitrile groups,

[0020] The content of the nitrile-containing units is 0.05 to 5.0 mol% relative to all units of the fluorinated copolymer (A).

[0021] The content of the tetrafluoroethylene-based units is 59.0 to 79.95 mol% relative to all units of the fluorinated copolymer (A).

[0022] The content of the above-mentioned perfluorinated (alkyl vinyl ether) based units is 20.0 to 40.95 mol relative to all units of the above-mentioned fluorinated copolymer (A). [3]

[0024] According to the fluorinated copolymer composition described in [1] or [2], the content of the monomer unit having at least one functional group selected from the group consisting of a carboxyl group and a group represented by the above formula (X) is 0.01 to 3.0 mol% relative to all units of the fluorinated copolymer (B).

[0025] The content of the tetrafluoroethylene-based units mentioned above is 90-99.89 mol% relative to all units of the fluorinated copolymer (B).

[0026] The content of the above-mentioned perfluorinated (alkyl vinyl ether) based units is 0.1 to 9.99 mol relative to all units of the above-mentioned fluorinated copolymer (B). [4]

[0028] The fluorinated copolymer composition according to any one of [1] to [3], wherein the content of the fluorinated copolymer (B) is 50 parts by mass or less relative to 100 parts by mass of the fluorinated copolymer (A). [5]

[0030] The fluorinated copolymer composition according to any one of [1] to [4], wherein the crosslinking agent is a compound having two or more amino groups,

[0031] The content of the crosslinking agent is 0.3 to 10 parts by mass relative to 100 parts by mass of the fluorinated copolymer (A). [6]

[0033] The fluorinated copolymer composition according to any one of [1] to [5], wherein the bulk density of the fluorinated copolymer (B) is 0.25 g / mL or less. [7]

[0035] A fluorinated copolymer composition comprising a fluorinated copolymer (A), a fluorinated copolymer (B), and a crosslinking agent.

[0036] The aforementioned fluorinated copolymer (A) has tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units.

[0037] The aforementioned fluorinated copolymer (B) is a fluorinated copolymer different from the aforementioned fluorinated copolymer (A), and contains units based on monomers having at least one functional group selected from the group represented by carboxyl groups and groups of formula (X), units based on tetrafluoroethylene, and units based on perfluorinated (alkyl vinyl ethers).

[0038] The above-mentioned fluorinated copolymer composition underwent a vulcanization test at 180°C according to JIS K6296. 90 Less than 10 minutes.

[0039] Formula (X) *-CO-O-CO-*

[0040] In equation (X), * represents the bonding position. [8]

[0042] According to the fluorinated copolymer composition of [7], wherein the fluorinated copolymer (A) contains units having nitrile groups,

[0043] The content of the nitrile-containing units is 0.05 to 5.0 mol% relative to all units of the fluorinated copolymer (A).

[0044] The content of the tetrafluoroethylene-based units is 59.0 to 79.95 mol% relative to all units of the fluorinated copolymer (A).

[0045] The content of the above-mentioned perfluorinated (alkyl vinyl ether) based units is 20.0 to 40.95 mol relative to all units of the above-mentioned fluorinated copolymer (A). [9]

[0047] According to the fluorinated copolymer composition of [7] or [8], the content of the monomer unit based on at least one functional group selected from the group consisting of a carboxyl group and a group represented by the above formula (X) is 0.01 to 3.0 mol% relative to all units of the fluorinated copolymer (B).

[0048] The content of the tetrafluoroethylene-based units mentioned above is 90-99.89 mol% relative to all units of the fluorinated copolymer (B).

[0049] The content of the above-mentioned perfluorinated (alkyl vinyl ether) based units is 0.1 to 9.99 mol relative to all units of the above-mentioned fluorinated copolymer (B).

[10]

[0051] The fluorinated copolymer composition according to any one of [7] to [9], wherein the content of the fluorinated copolymer (B) is 50 parts by mass or less relative to 100 parts by mass of the fluorinated copolymer (A).

[11]

[0053] The fluorinated copolymer composition according to any one of [7] to

[10] , wherein the crosslinking agent is a compound having two or more amino groups,

[0054] The content of the crosslinking agent is 0.3 to 10 parts by mass relative to 100 parts by mass of the fluorinated copolymer (A).

[12]

[0056] The fluorinated copolymer composition according to any one of [7] to

[11] , wherein the bulk density of the fluorinated copolymer (B) is 0.25 g / mL or less.

[13]

[0058] A crosslinked rubber article obtained from any one of the fluorinated copolymer compositions described in [1] to

[12] .

[0059] The effects of the invention

[0060] According to the present invention, a fluorinated copolymer composition and a cross-linked rubber article can be provided, wherein the aforementioned fluorinated copolymer composition is capable of forming a cross-linked rubber article in which weight loss that begins after a predetermined time when used for a long period of time under plasma irradiation is suppressed. Detailed Implementation

[0061] The meanings of the terms used in this invention are as follows.

[0062] The range of values ​​represented by "~" refers to the range of values ​​recorded before and after "~" as the lower and upper limits.

[0063] "Unit" refers to the atomic group directly formed by the polymerization of monomers, originating from one molecule of the aforementioned monomer, and the atomic group obtained by chemically transforming a portion of the aforementioned atomic group. "Monomer-based unit" is also referred to as "unit" below.

[0064] "Rubber" refers to rubber that exhibits the properties defined by JIS K 6200:2008, and is distinguished from "resin".

[0065] [Fluoropolymer Composition (First Embodiment)]

[0066] The fluorinated copolymer composition of the first embodiment of the present invention (hereinafter also referred to as "the Composition 1") comprises a fluorinated copolymer (A), a fluorinated copolymer (B), and a crosslinking agent.

[0067] The aforementioned fluorinated copolymer (A) has tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units.

[0068] The aforementioned fluorinated copolymer (B) is a fluorinated copolymer different from the fluorinated copolymer (A), and contains units based on monomers having at least one functional group selected from the group consisting of carboxyl groups and groups represented by formula (X), units based on tetrafluoroethylene, and units based on perfluorinated (alkyl vinyl ether), and has a particle size D90 of less than 4.0 μm.

[0069] When cross-linked rubber articles obtained using this composition 1 are used for extended periods under plasma irradiation, weight loss after a specified time is suppressed (hereinafter also referred to as "effects of the present invention"). The details of the reason are not yet clear, but it is speculated to be based on the following reasons.

[0070] As a characteristic feature of this composition 1, for example, the particle size D90 of the fluorinated copolymer (B) is 4.0 μm or less. It is speculated that when the fluorinated copolymer (B) contains such a controlled particle size D90, the fluorinated copolymer (B) can be uniformly dispersed in the resulting crosslinked rubber article, thus achieving the desired effect of the present invention. In addition, other particle sizes include particle size D10 and particle size D50 (median particle size), among which it is determined that particle size D90 has a strong influence on the effect of the present invention.

[0071] The effects of the present invention can be evaluated, for example, by using the weight reduction ratio (mass% / time (h)) as an indicator.

[0072] The weight reduction ratio (mass% / time (h)) can be determined, for example, by the method described in the examples. The weight reduction ratio (mass% / hour (h), zone A) from the start of plasma treatment to 1.5 hours is preferably 2.150 or less, more preferably 2.125 or less. The weight reduction ratio (mass% / hour (h), zone B) from 1.5 hours to 3.0 hours from the start of plasma treatment is preferably 2.150 or less, more preferably 2.120 or less. The weight reduction ratio (mass% / hour (h), zone C) from 3.0 hours to 6.0 hours from the start of plasma treatment is preferably 2.040 or less, more preferably 2.038 or less. When the weight reduction ratio (mass% / time (h)) is within the above range, the occurrence of device malfunctions can be suppressed when using the apparatus employing the cross-linked rubber article of the present invention. Furthermore, when manufacturing semiconductor products, etc., using the apparatus employing the cross-linked rubber article of the present invention, the generation of particle-based defects can be suppressed. Zone C is particularly preferred to be within the above range.

[0073] Fluorinated copolymer (A)

[0074] This composition 1 comprises a fluorinated copolymer (A).

[0075] The fluorinated copolymer (A) has units based on tetrafluoroethylene (hereinafter also referred to as "TFE") and units based on perfluoro(alkyl vinyl ether) (hereinafter also referred to as "PAVE").

[0076] Fluorinated copolymer (A) cannot fully recover its original shape when stretched, but it exhibits properties that are enhanced by cross-linking, i.e., it exhibits the properties of rubber.

[0077] The content of TFE units relative to all units of the fluorinated copolymer (A) is preferably 60.0 to 80.0 mol%, more preferably 59.0 to 79.95 mol%, and even more preferably 64.0 to 72.0 mol%.

[0078] The PAVE unit is based on perfluorinated (alkyl vinyl ether) units.

[0079] From the perspective of excellent polymerization reactivity and rubber properties, the monomer represented by formula (1) is preferred by PAVE.

[0080] CF2 = CF - OR f2 (1)

[0081] In equation (1), R f2 It refers to perfluoroalkyl groups with 1 to 10 carbon atoms.

[0082] From the perspective of superior polymerization reactivity, R f2The number of carbon atoms is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 3.

[0083] Perfluoroalkyl groups can be linear or branched.

[0084] Specific examples of PAVE include perfluoro(methyl vinyl ether) (hereinafter also referred to as "PMVE"), perfluoro(ethyl vinyl ether) (hereinafter also referred to as "PEVE"), and perfluoro(propyl vinyl ether) (hereinafter also referred to as "PPVE"), with PMVE or PPVE being preferred.

[0085] From the perspective of superior elasticity of cross-linked rubber articles, the content of PAVE units relative to all units of the fluorinated copolymer (A) is preferably 20.0 to 40.95 mol%, more preferably 20.0 to 37.0 mol%, and even more preferably 27.0 to 33.0 mol%. The preferred content is the same when PMVE or PPVE is used as PAVE.

[0086] The fluorinated copolymer (A) preferably has: in addition to units based on TFE monomers and units based on PAVE monomers, it is based on monomers having nitrile groups (hereinafter also referred to as "R"). CN The unit of ”).

[0087] Considering the superior effects of the present invention, R CN Preferably, it further has fluorine atoms, and more preferably the monomer represented by formula (2).

[0088] CR 11 R 12 =CR 13 -R 14 -CN (2)

[0089] In equation (2), R 11 R 12 and R 13 Each can independently represent a hydrogen atom, a fluorine atom, or a methyl group. R 14 It refers to a perfluorocarbon group with 1 to 10 carbon atoms in a divalent state, or a group having an ether-like oxygen atom at the end of the perfluorocarbon group or between carbon-carbon bonds.

[0090] From R CN Based on its excellent polymerization reactivity, R 11 R 12 and R 13 Preferred fluorine or hydrogen atoms, R 11 R 12 and R 13 More preferably, fluorine or hydrogen atoms are used, from the viewpoint that cross-linked rubber articles have superior release properties and heat resistance. 11 R12 and R 13 All fluorine atoms were further optimized.

[0091] R 14 It can be any of the following: linear, branched, and cyclic, preferably linear or branched. R 14 The number of carbon atoms is preferably 2 to 8, more preferably 3 to 7, even more preferably 4 to 7, and particularly preferably 4 to 6.

[0092] R 14 From the viewpoint that cross-linked rubber articles have superior rubber properties, it is preferable to have ether-containing oxygen atoms.

[0093] R 14 The number of ether oxygen atoms in the sample is preferably 1 to 3, more preferably 1 or 2.

[0094] As a specific example of the monomer represented by equation (2), the following can be cited:

[0095] From the viewpoint that cross-linked rubber articles have better release properties and heat resistance, 8CNVE or MV5CN is preferred.

[0096] From the viewpoint that the present invention offers superior performance, R CN The content of the unit relative to all units of the fluorinated copolymer (A) is preferably 0.05 to 5.0 mol%, more preferably 0.1 to 3.0 mol%, and even more preferably 0.2 to 1.5 mol%.

[0097] Fluorinated copolymers (A) may have units based on monomers other than those described above (hereinafter also referred to as "other monomers").

[0098] Specific examples of other monomers include vinylidene fluoride (hereinafter also referred to as "VdF"), hexafluoropropylene (hereinafter also referred to as "HFP"), chlorotrifluoroethylene, monomers having two or more polymerizable unsaturated bonds (hereinafter also referred to as "BO"), monomers represented by formula (6), ethylene, propylene and monomers having halogen atoms (hereinafter also referred to as "other monomers having halogen atoms").

[0099] Other specific examples of monomers containing halogen atoms include bromotrifluoroethylene and iodotrifluoroethylene.

[0100] The BO unit is a unit based on monomers having two or more polymerizable unsaturated bonds.

[0101] Specific examples of polymerizable unsaturated bonds include carbon-carbon double bonds (C=C) and carbon-carbon triple bonds (C≡C).

[0102] From the perspective of superior polymerization reactivity, the number of polymerizable unsaturated bonds in BO is preferably 2 to 6, more preferably 2 or 3, and even more preferably 2.

[0103] From the perspective that cross-linked rubber articles have less compression set at high temperatures, BO preferably has fluorine atoms.

[0104] For BO, the monomer represented by equation (3) is preferred.

[0105] (CR 31 R 32 =CR 33 ) a3 R 34 (3)

[0106] In equation (3), R 31 R 32 and R 33 Each atom independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. a3 represents an integer from 2 to 6. R 34 This refers to a perfluoroalkyl group with 1 to 10 carbon atoms and an a3 valence, or a group having an ether-like oxygen atom at the end of the perfluoroalkyl group or between carbon-carbon bonds. Multiple R 31 Multiple R 32 and multiple R 33 They can be the same or different from each other, but it is preferred that they are the same.

[0107] a3 is preferably 2 or 3, more preferably 2.

[0108] Starting from the superior polymerization reactivity of BO, R 31 R 32 and R 33 Preferred fluorine or hydrogen atoms, R 31 R 32 and R 33 More preferably, fluorine or hydrogen atoms are used, considering the heat resistance and chemical resistance of cross-linked rubber articles. 31 R 32 and R 33 All fluorine atoms were further optimized.

[0109] R 34 It can be any of the following: linear, branched, and cyclic, preferably linear or branched, and more preferably linear. R 34The number of carbon atoms is preferably 2 to 10, more preferably 3 to 8, even more preferably 3 to 6, and particularly preferably 3 to 5.

[0110] R 34 From the viewpoint that cross-linked rubber articles have superior rubber properties, it is preferable to have ether-containing oxygen atoms.

[0111] R 34 The number of ether-containing oxygen atoms is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1 or 2. R 34 The ether oxygen atom in R is preferably present in R 34 The end of.

[0112] Among the monomers represented by equation (3), the monomers represented by equation (4) and equation (5) can be cited as specific examples of suitable monomers.

[0113] (CF2=CF)2R 41 (4)

[0114] In equation (4), R 41 It refers to a perfluorocarbon group with 2 to 10 carbon atoms in a divalent state, or a group having an ether-like oxygen atom at the end of the perfluorocarbon group or between carbon-carbon bonds.

[0115] As specific examples of the monomers represented by equation (4), we can give examples of CF2=CFO(CF2)2OCF=CF2, CF2=CFO(CF2)3OCF=CF2, CF2=CFO(CF2)4OCF=CF2, and CF2=CFO(CF2)6OCF=CF2. 2、 CF2=CFO(CF2)8OCF=CF2, CF2=CFO(CF2)2OCF(CF3)CF2OCF=CF2, CF2=CFO(CF2)2O(CF(CF3)CF2O)2CF=CF2, CF2=CFOCF2O(CF2CF2O)2CF=CF2, CF2=CFO(CF2O)3O(CF(CF 3)CF2O)2CF=CF2, CF2=CFOCF2CF(CF3)O(CF2)2OCF(CF3)CF2OCF=CF2 and CF2=CFOCF2CF2O(CF2O)2CF2CF2OCF=CF2, preferably CF2=CFO(CF2)3OCF=CF2 or CF2=CFO(CF2)4OCF=CF2.

[0116] (CH2=CH)2R 51 (5)

[0117] In equation (5), R 51It refers to a perfluorocarbon group with 2 to 10 carbon atoms in a divalent state, or a group having an ether-like oxygen atom at the end of the perfluorocarbon group or between carbon-carbon bonds.

[0118] Specific examples of the monomers represented by equation (5) include CH2=CH(CF2)2CH=CH2, CH2=CH(CF2)4CH=CH2 and CH2=CH(CF2)6CH=CH2, with CH2=CH(CF2)6CH=CH2 being preferred.

[0119] During BO copolymerization, the polymerizable double bonds at the ends of BO react during polymerization to obtain a branched fluorinated copolymer (A).

[0120] CF2 = CF - OR f6 (6)

[0121] In equation (6), R f6 R represents a perfluoroalkyl group having 1 to 8 carbon atoms and containing 1 to 5 ether-containing oxygen atoms. f6 The number of carbon atoms is preferably 1 to 6, and more preferably 1 to 5.

[0122] Specific examples of the monomers represented by formula (6) include perfluorinated (3,6-dioxa-1-heptene), perfluorinated (3,6-dioxa-1-octene), and perfluorinated (5-methyl-3,6-dioxa-1-nonene).

[0123] When the fluorinated copolymer (A) contains other monomer units, from the perspective of excellent rubber properties of the crosslinked rubber article, the content of the other monomer units relative to all units of the fluorinated copolymer (A) is preferably 0.01 to 20 mol%, more preferably 0.5 to 10 mol%, and even more preferably 1 to 5 mol%.

[0124] From the perspective of further improving the effects of the present invention, the fluorinated copolymer (A) is preferably a fully fluorinated fluorinated copolymer.

[0125] "Fully fluorinated fluorinated copolymers" refer to fluorinated copolymers that substantially do not contain hydrogen atoms bonded to carbon atoms, have fluorine atoms that replace the hydrogen atoms, and whose main chain is formed by a chain of carbon atoms. The side chains of fully fluorinated fluorinated copolymers may optionally have multivalent atoms other than carbon atoms, with oxygen atoms being preferred.

[0126] "Substantially contains no hydrogen atoms" means that the hydrogen atom content in the fully fluorinated fluorinated copolymer is 0.5% by mass or less, preferably 0.1% by mass or less, more preferably 0.07% by mass or less, and even more preferably 0.05% by mass or less. When the hydrogen atom content is within the above range, good heat resistance or chemical resistance is easily obtained.

[0127] The fluorinated copolymer (A) may contain iodine atoms. In this case, it is preferable that the iodine atoms are located at the ends of the polymer chains of the fluorinated copolymer (A).

[0128] Examples of iodine atoms include iodine atoms derived from iodine compounds that function as chain transfer agents (described later), and iodine atoms in units of monomers containing iodine atoms, such as iodotrifluoroethylene, which are other monomers containing halogen atoms. Iodine atoms derived from iodine compounds that function as chain transfer agents are preferred.

[0129] When the fluorinated copolymer (A) contains iodine atoms, the content of iodine atoms relative to the total mass of the fluorinated copolymer (A) is preferably 0.01 to 5.0% by mass, more preferably 0.05 to 2.0% by mass, and even more preferably 0.05 to 1.0% by mass. When the content of iodine atoms is within the above range, the crosslinking reactivity of the fluorinated copolymer (A) is improved, and the mechanical properties of the crosslinked rubber article are excellent.

[0130] The content of the fluorinated copolymer (A) relative to the total mass of the composition 1 is preferably 55 to 95% by mass, more preferably 65 to 90% by mass, and even more preferably 75 to 85% by mass.

[0131] As an example of a method for manufacturing fluorinated copolymer (A), a method of copolymerizing the above monomers in the presence of a free radical polymerization initiator can be cited.

[0132] Water-soluble polymerization initiators or redox polymerization initiators are preferred as free radical polymerization initiators.

[0133] Specific examples of water-soluble polymerization initiators include persulfate-based initiators such as ammonium persulfate, sodium persulfate, and potassium persulfate, and organic polymerization initiators such as disuccinic acid peroxide and azobisisobutylamidine dihydrochloride. Persulfate-based initiators are preferred, and ammonium persulfate is more preferred.

[0134] As redox polymerization initiators, examples include polymerization initiators composed of persulfates and reducing agents, preferably polymerization initiators capable of polymerizing each monomer within a polymerization temperature range of 0 to 85°C. Specific examples of persulfates constituting redox polymerization initiators include alkali metal salts of persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, with ammonium persulfate being preferred. Specific examples of reducing agents combined with persulfates include thiosulfates, sulfites, bisulfites, metabisulfites, and hydroxymethanesulfinates, with hydroxymethanesulfinates being preferred, and sodium hydroxymethanesulfinate more preferred.

[0135] In the method for manufacturing fluorinated copolymer (A), the monomer can be copolymerized together with a free radical polymerization initiator in the presence of a chain transfer agent.

[0136] The chain transfer agent is preferably an iodine compound, more preferably an iodine compound represented by the formula RI2. In the above formula, R represents an alkylene group or a perfluoroalkylene group having 3 or more carbon atoms (preferably 3 to 8 carbon atoms).

[0137] Specific examples of iodine compounds represented by formula RI2 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.

[0138] As an iodine compound, an iodine compound having a perfluoroalkylene group is preferred, and 1,4-diiodoperfluorobutane is more preferred.

[0139] If the above monomers are copolymerized in the presence of these iodine compounds, iodine atoms can be introduced into the fluorinated copolymer (A).

[0140] For details regarding the other components and manufacturing methods used in the manufacture of the fluorinated copolymer (A), please refer to the methods described in paragraphs 0019 to 0034 of International Publication No. 2010 / 082633.

[0141] Fluorinated copolymer (B)

[0142] This composition 1 comprises a fluorinated copolymer (B).

[0143] Fluorinated copolymer (B) is a fluorinated copolymer different from fluorinated copolymer (A), which contains: a unit having at least one functional group (hereinafter also referred to as "specific functional group") selected from the group consisting of carboxyl group and group represented by formula (X), a TFE unit, and a PAVE-based unit.

[0144] In other words, the fluorinated copolymer (B) has: units with specific functional groups, TFE units, and PAVE units.

[0145] The specific functional group can be any one or both of the carboxyl group and the group represented by formula (X).

[0146] Formula (X) *-CO-O-CO-*

[0147] In equation (X), * represents the bonding position.

[0148] The unit having a specific functional group is preferably based on a monomer having a specific functional group (hereinafter also referred to as "R"). X The unit of ”).

[0149] R X It can have multiple specific functional groups. In R XWhen a device has multiple specific functional groups, the types of these specific functional groups can be the same or different from each other.

[0150] R X As a monomer, it therefore possesses polymerizable unsaturated bonds. Specific examples of polymerizable unsaturated bonds are described above.

[0151] R X Preferably, it is a compound having one specific functional group and one polymerizable unsaturated bond.

[0152] Examples of monomers containing a carboxyl group include itaconic anhydride (hereinafter also referred to as "IAH"), citraconic anhydride (hereinafter also referred to as "CAH"), 5-norbornene-2,3-dicarboxylic anhydride (also known as Nadic anhydride, hereinafter also referred to as "NAH"), and maleic anhydride, which are anhydrides of unsaturated dicarboxylic acids.

[0153] The group that includes the group represented by formula (X) is preferably a group formed by removing one hydrogen atom from an acid anhydride.

[0154] Examples of monomers having the group represented by formula (X) include itaconic anhydride (hereinafter also called "IAH"), citraconic anhydride (hereinafter also called "CAH"), 5-norbornene-2,3-dicarboxylic anhydride (also called nadic anhydride, hereinafter also called "NAH"), maleic anhydride, and other anhydrides of unsaturated dicarboxylic acids.

[0155] From the perspective of reactivity with the nitrile groups that may be present in the fluorinated copolymer (A), R X Preferably, the monomer contains a group having the group represented by formula (X). From the point of view, it makes the manufacture of the fluorinated copolymer (B) easier. More preferably, it contains at least one selected from the group consisting of IAH, CAH and NAH. More preferably, it contains NAH. Particularly preferred is NAH.

[0156] R X One type can be used alone, or two or more types can be used in combination.

[0157] The TFE and PAVE units of the fluorinated copolymer (B) are the same as those of the fluorinated copolymer (A).

[0158] The fluorinated copolymer (B) may have units based on monomers other than those described above (hereinafter also referred to as "other monomers"). Specific examples and preferred embodiments of the other monomers are the same as those of the other monomers in the fluorinated copolymer (A).

[0159] Fluorinated copolymers (B) can further have specific functional groups as end groups of the main chain.

[0160] Specific functional groups that are terminal groups of the main chain can be introduced by free radical polymerization initiators and chain transfer agents used in the manufacture of fluorinated copolymers (B).

[0161] Fluorinated copolymer (B) is in particulate form. That is, fluorinated copolymer (B) is in the form of fluorinated copolymer (B) particles.

[0162] The particle size D90 of the fluorinated copolymer (B) is 4.0 μm or less, preferably 3.5 μm or less, and more preferably 3.0 μm or less. The lower limit is preferably 1.0 μm or more, and more preferably 2.0 μm or more.

[0163] The particle size D90 of the fluorinated copolymer (B) is the volume-based cumulative 90% diameter (D90) determined by laser diffraction / scattering. That is, the particle size distribution is determined by laser diffraction / scattering, and the total volume of the particle cluster is taken as 100% to obtain a cumulative curve. The particle size at the point where the cumulative volume is 90% on the cumulative curve is the particle size.

[0164] Methods for controlling the particle size D90 of fluorinated copolymers (B) include, for example, pulverization and grading.

[0165] The bulk density of the fluorinated copolymer (B) is preferably 0.50 g / mL or less, more preferably 0.30 g / mL or less, and even more preferably 0.25 g / mL or less. The lower limit is preferably 0.01 g / mL or more, more preferably 0.10 g / mL or more.

[0166] Methods for determining bulk density include, for example, those shown in the Examples section.

[0167] From the viewpoint of achieving better results with the present invention, the content of the unit having a specific functional group relative to all units of the fluorinated copolymer (B) is preferably 0.01 to 3 mol%, more preferably 0.03 to 2 mol%, and even more preferably 0.05 to 1 mol%. When NAH is used as the unit having a specific functional group, the preferred range is also the same.

[0168] From the viewpoint of achieving better results from the present invention, the content of TFE units relative to all units of the fluorinated copolymer (B) is preferably 90 to 99.89 mol%, more preferably 95 to 99.47 mol%, and even more preferably 96 to 98.95 mol%.

[0169] From the viewpoint of achieving better results with the present invention, the content of PAVE units relative to all units of the fluorinated copolymer (B) is preferably 0.1 to 9.99 mol%, more preferably 0.5 to 4.97 mol%, and even more preferably 1 to 3.95 mol%. The preferred range is the same when PPVE units are used as PAVE units.

[0170] From the viewpoint of achieving better results in this invention, the content of the fluorinated copolymer (B) relative to 100 parts by mass of the fluorinated copolymer (A) is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less.

[0171] The content of fluorinated copolymer (B) relative to 100 parts by mass of fluorinated copolymer (A) is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more.

[0172] The content of the fluorinated copolymer (B) relative to the total mass of the composition 1 is preferably 1 to 40% by mass, more preferably 1 to 30% by mass, and even more preferably 1 to 20% by mass.

[0173] As an example of a method for manufacturing fluorinated copolymer (B), a method for copolymerizing the above monomers in the presence of a free radical polymerization initiator can be cited, the details of which are described in International Publication No. 2016 / 017801.

[0174] Crosslinking agent

[0175] This composition 1 contains a crosslinking agent.

[0176] Specific examples of crosslinking agents include organic peroxides and compounds having two or more amino groups (hereinafter also referred to as "polyamine compounds"). From the perspective of obtaining crosslinked rubber articles with excellent crosslinking properties of fluorinated copolymers (A) and less compression set under high temperature and high compression, polyamine compounds are preferred.

[0177] The polyamine compound can be a compound formed by replacing the hydrogen atoms of an aliphatic hydrocarbon with an amino group, or a compound formed by replacing the hydrogen atoms of an aromatic hydrocarbon with an amino group. From the viewpoint of better performance of the present invention, it is preferred to form a compound formed by replacing the hydrogen atoms of an aromatic hydrocarbon with an amino group.

[0178] The polyamine compound preferably contains fluorine atoms. As a result, the compatibility with the fluorinated copolymer (A) becomes good, and thus cross-linked rubber articles with lower compression set under high temperature and high compression can be obtained.

[0179] Specific examples of polyamine compounds 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 also called "BOAP," alternative name: 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'-methylenediphenylamine, m-phenylenediamine, adipic acid dihydrazide, and compounds represented by formula (XII) of Japanese Patent No. 5833657. From the viewpoint of superior effects of the present invention, BOAP is preferred.

[0180] The content of crosslinking agent is preferably 0.3 to 10 parts by mass relative to 100 parts by mass of fluorinated copolymer (A), more preferably 0.3 to 5 parts by mass, and even more preferably 0.5 to 3 parts by mass.

[0181] <Other Ingredients>

[0182] This composition 1 may also contain other ingredients besides those described above.

[0183] Specific examples of other components include acid absorbents (e.g., fatty acid esters, fatty acid metal salts, and oxides of divalent metals (magnesium oxide, calcium oxide, zinc oxide, and lead oxide, etc.)), fillers and reinforcing materials (e.g., carbon black, barium sulfate, calcium metasilicate, calcium carbonate, titanium dioxide, silicon dioxide, fluorinated copolymers other than fluorinated copolymers (A) and fluorinated copolymers (B) (e.g., tetrafluoroethylene-fluoroalkyl vinyl ether copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, and ethylene-tetrafluoroethylene copolymers, etc.), polytetrafluoroethylene (PTFE), aromatic polyesters, polyamide-imides and thermoplastic polyimides, clay, talc), scorch inhibitors (e.g., compounds containing phenolic hydroxyl groups such as bisphenol A, quinones such as hydroquinone, α-methylstyrene dimers such as 2,4-di(3-isopropylphenyl)-4-methyl-1-pentene), crown ethers (e.g., 18-crown-6), and release agents (e.g., sodium stearate).

[0184] When the composition 1 contains other components, the total content of the other components relative to 100 parts by weight of the fluorinated copolymer (A) is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight, and even more preferably 3 to 5 parts by weight.

[0185] The T value of this composition 1 in the vulcanization test at 180°C according to JIS K6296 90 Preferably, it should be less than 10 minutes. The lower limit is preferably more than 1 minute.

[0186] T90 The determination method can be exemplified by the determination method shown in the Examples section.

[0187] As a method for manufacturing this composition 1, one example is a method of mixing the above-mentioned components. The mixing of the components can be carried out using rubber mixing equipment such as rollers, kneaders, Banbury mixers, and extruders.

[0188] Alternatively, the mixture can be shaped after obtaining the mixture of the above-mentioned components. Specific examples of the shaping method of the mixture include compression molding, injection molding, extrusion molding, calendering, or shaping by dissolving in a solvent and impregnating or coating onto a substrate.

[0189] [Fluoropolymer Composition (Second Embodiment)]

[0190] The fluorinated copolymer composition of the second embodiment of the present invention (hereinafter also referred to as "composition 2") comprises a fluorinated copolymer (A), a fluorinated copolymer (B), and a crosslinking agent.

[0191] The aforementioned fluorinated copolymer (A) has tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units.

[0192] The aforementioned fluorinated copolymer (B) is a fluorinated copolymer different from fluorinated copolymer (A), and contains units based on monomers having at least one functional group selected from the group represented by carboxyl groups and groups of formula (X), units based on tetrafluoroethylene, and units based on perfluorinated (alkyl vinyl ethers).

[0193] The T value of the fluorinated copolymer composition in the vulcanization test at 180°C according to JIS K6296 90 Less than 10 minutes.

[0194] It should be noted that the types and contents of various components, the physical properties of the composition, and other elements in the second embodiment described above are the same as those in the first embodiment, and the preferred methods are also the same. It should also be noted that the particle size D90 of the fluorinated copolymer (B) in the second embodiment is not limited to 4.0 μm or less, but is preferably 4.0 μm or less.

[0195] The details of the reasons for achieving the desired effect through the composition of this composition 2 are not yet clear, but it is believed that by shortening the crosslinking time of this composition 2, the time of exposure to heat of this composition 2 is shortened, making it less prone to thermal degradation, thereby increasing the heat resistance of the crosslinked product and achieving the desired effect.

[0196] Cross-linked rubber products

[0197] The crosslinked rubber article of the present invention is a rubber article obtained by crosslinking the fluorine-containing copolymer (A) in the above-described present composition (hereinafter, "present composition 1" and "present composition 2" are collectively referred to as "present composition").

[0198] As a method for crosslinking the fluorine-containing copolymer (A) in the present composition, a method of crosslinking by heating the present composition is preferred.

[0199] As specific examples of the crosslinking method using heating, there can be mentioned heat and pressure crosslinking, steam crosslinking, injection molding crosslinking, hot air crosslinking, molten salt crosslinking, fluidized bed crosslinking, and rotary crosslinking (corresponding to Japanese: ロート架橋).

[0200] The heating conditions are preferably 1 second to 24 hours at 100 to 400°C.

[0201] The crosslinked rubber obtained by heating the present composition (primary crosslinking) can also be further heated for secondary crosslinking. By performing secondary crosslinking, the mechanical properties, compression set, and other properties of the crosslinked rubber can be stabilized or improved.

[0202] The heating conditions during secondary crosslinking are preferably 30 minutes to 48 hours at 80 to 350°C.

[0203] As a crosslinking method other than crosslinking the fluorine-containing copolymer (A) by heating, there can be mentioned a method of crosslinking the fluorine-containing copolymer (A) by irradiating the present composition with radiation. As specific examples of the radiation to be irradiated, there can be mentioned electron beams and ultraviolet rays.

[0204] <Use>

[0205] The crosslinked rubber article is suitable for materials such as O-rings, sheets, gaskets, oil seals, diaphragms, and V-rings. In addition, it can also be applied to heat-resistant and chemical-resistant sealing materials, heat-resistant and oil-resistant sealing materials, wire covering materials, sealing materials for semiconductor manufacturing devices, sealing materials for liquid crystal display panel manufacturing devices, sealing materials for light-emitting diode manufacturing devices, corrosion-resistant rubber coatings, sealing materials for urea-based greases, etc., rubber coatings, adhesive rubbers, hoses, tubes, calendered sheets (rollers), sponges, rubber rollers, components for oil drilling, heat sinks, solution crosslinked bodies, rubber sponges, bearing seals (for urea greases, etc.), linings (chemical-resistant), insulating sheets for automobiles, insulating sheets for electronic devices, rubber bands for watches, gaskets for endoscopes (amine-resistant), corrugated hoses (processed from calendered sheets), gaskets / valves for water heaters, fender materials (marine civil engineering, ships), fibers / non-woven fabrics (protective clothing, etc.), substrate sealing materials, rubber gloves, stators of single-axis eccentric screw pumps, components for urea SCR systems, anti-vibration agents, shock absorbers, sealants, additives to other materials, and toys.

[0206] Example

[0207] The present invention will be described in detail below with examples. Example 1 is an embodiment, and Examples 2 to 4 are comparative examples. However, the present invention is not limited to these examples.

[0208] [Determination of the composition of fluorinated copolymers]

[0209] The content (molar percentage) of each unit in the fluorinated copolymer (A-1) described later is determined by... 19 Calculated by F-nuclear magnetic resonance (NMR) analysis.

[0210] The content (molar percentage) of each unit in the fluorinated copolymers (B-1), (C-1) to (C-3) described later was calculated by melt NMR analysis and fluorine content analysis. The content of the NAH unit was calculated by the following infrared absorption spectroscopy analysis.

[0211] [Infrared Absorption Spectroscopy Analysis]

[0212] 200 μm films were obtained by stamping the fluorinated copolymers (B-1), (C-1) to (C-3) described later. In the infrared absorption spectrum, the absorption peak of the NAH-based units in the fluorinated copolymers (B-1), (C-1) to (C-3) all appeared at 1778 cm⁻¹. -1 The absorbance of this absorption peak was measured using the molar absorptivity of NAH, which is 20810 mol / L. -1 ·l·cm -1 Calculate the proportion of NAH-based units in each of the fluorinated copolymers (B-1), (C-1) to (C-3).

[0213] [Particle size D90]

[0214] The fluorinated copolymers (B-1), (C-1) to (C-3) described later were dispersed in isopropanol to prepare a dispersion (solid component concentration 0.5% by mass). The particle size D90 of the fluorinated copolymers (B-1) and the like in the dispersion was measured using a laser diffraction / scattering particle size distribution measuring device (LMS-2000e, manufactured by Seishin Corporation).

[0215] [Bulk Density]

[0216] The bulk density of fluorinated copolymers (B-1) and the like was determined using an ABD powder property tester (ABD-100 type) manufactured by Ritsukai Chemical Equipment Co., Ltd., and a 100 mL sample container.

[0217] Specifically, the fluorinated copolymer (B-1) is supplied to the sample container in a manner that fills the container in 30-60 seconds. The portion of the fluorinated copolymer (B-1) extending beyond the top of the sample container and forming a hill-like shape is leveled with a scraper. Any fluorinated copolymer (B-1) adhering to the periphery of the sample container is dusted off. The mass of sample container 1 filled with fluorinated copolymer (B-1) is measured using an electronic balance. The mass of the empty sample container 2 is also measured. Next, the density (g / mL) is calculated by subtracting the mass of sample container 2 from the mass of sample container 1, and this value is taken as the bulk density (g / mL).

[0218] [T 90 ]

[0219] Each of the fluorinated copolymer compositions described later was processed into a sheet with a thickness of 3 mm, and then cut into 10 g pieces to obtain cut samples. The cut samples were sandwiched between two polyester films (ALFA Technologies, PART#F0311-S, 130 mm × 130 mm × 24 μm) from both sides of the main surface to obtain test samples. The test samples were placed on a mold. Then, the torque (dNm) was measured under the following conditions: measuring apparatus: PREMER RPA (Alpha Technologies), mold shape: D0380, 180°C, 20 minutes, 100 cpm, Angle: 3.00 deg. The minimum torque value was set to 0%, and the maximum torque value was set to 100%. The processing time for obtaining 90% of the torque value was set to T. 90 .

[0220] [Plasma Experiment]

[0221] The O-rings fabricated in the examples described below were cut at three points along the thickness direction, dividing the outer circumference into three equal parts, to prepare samples for measurement. Plasma etching was performed using a CPE-200AHM (Kei Semiconductor) machine under the following conditions: gas type: N2 / NF3 (NF3 mixing ratio: 20%), power: 300W, pressure: 26Pa. Samples were taken after 1.5 hours, 3 hours, and 6 hours of plasma treatment, and their mass (to one decimal place) was measured using an Azpro electronic balance (BCA64I-1SJP Sartorius).

[0222] Next, the plasma treatment time was divided into three zones: A (0-1.5 hours), B (1.5-3.0 hours), and C (3.0-6.0 hours). The percentage reduction in sample weight (mass% / time (h)) was calculated for each zone relative to the mass of the sample before plasma treatment per unit time.

[0223] For example, if the mass of the sample before plasma treatment is 10.0 g, the mass of the sample after 1.5 hours of plasma treatment is 8.0 g, and the mass of the sample after 3.0 hours of plasma treatment is 5.0 g, then the weight reduction ratio of the sample during plasma treatment per unit time in zone A, relative to the mass of the sample before plasma treatment, is [100×(10.0-8.0) / 10.0] / (1.5)=13.33 (mass% / h). Furthermore, relative to the mass of the sample before plasma treatment per unit time in zone A+B, the weight reduction ratio of the sample during plasma treatment is [100×(10.0-5.0) / 10.0] / (3.0)=16.67 (mass% / h), and the weight reduction ratio of the sample in zone B is 16.67-13.33=3.34 (mass% / h).

[0224] [Manufacturing of Fluorinated Copolymer (A-1)]

[0225] After degassing a 20L stainless steel pressure reactor equipped with an anchor-type agitator, 7.2L of ultrapure water, 880g of a 30% (w / w) solution of C2F5OCF2CF2OCF2COONH4 (as an emulsifier), 7.3g of 8CNVE, and 15.9g of a 5% (w / w) aqueous solution of disodium hydrogen phosphate·12-hydrate were added to purge the gas phase with nitrogen. While stirring with the anchor-type agitator at 375 rpm, 137g of TFE and 635g of PMVE were added into the reactor, and the internal temperature was raised to 80°C. The reactor internal pressure was 0.90 MPa (gauge). 28mL of a 3% (w / w) aqueous solution of ammonium persulfate (APS) was added to initiate polymerization. The molar ratio of the monomers added before polymerization (hereinafter referred to as "initial added monomers") is TFE:PMVE:8CNVE = 26.3:73.3:0.4.

[0226] After polymerization begins, monomers are introduced as polymerization proceeds, as described below. Hereinafter, the introduction of monomers after polymerization begins will be referred to as "post-addition," and the monomers introduced after polymerization begins will be referred to as "post-added monomers."

[0227] When the pressure inside the reactor drops to 0.89 MPa, TFE is injected to raise the pressure inside the reactor to 0.90 MPa. This operation is repeated, with 3.7 g of 8CNVE, 74 g of PMVE, and 3.7 g of 8CNVE injected sequentially each time 119.3 g of TFE is injected.

[0228] When the polymerization rate decreases, add an appropriate amount of 3% (w / w) aqueous solution of APS. The total amount of 3% (w / w) aqueous solution of APS added after the start of polymerization is 35 mL.

[0229] At the end of the cycle when the total added TFE mass was 1073.7 g, 119.3 g of TFE was added. When the total added TFE mass reached 1193 g, the addition of subsequent monomers was stopped, the reactor temperature was cooled to 10°C, and the polymerization reaction was stopped, yielding a latex containing a fluorinated copolymer. The polymerization time was 375 minutes. Furthermore, the total added masses of each subsequent monomer were: TFE 1193 g, PMVE 666 g, and 8CNVE 66.6 g, which, when converted to a molar ratio, were TFE:PMVE:8CNVE = 74.0:25.0:1.0.

[0230] Latex was added to a 5% (w / w) aqueous solution of potassium aluminum sulfate to cause the fluorinated copolymer to coagulate and separate. The fluorinated copolymer was filtered, washed with ultrapure water, and vacuum dried at 50°C to obtain a white fluorinated copolymer (A-1). The molar ratio of each unit in the obtained fluorinated copolymer (A-1) was TFE unit: PMVE unit: 8CNVE unit = 70.9: 28.6: 0.5.

[0231] [Fluoropolymer (B-1)]

[0232] The "fluorinated copolymer (X1-1)" from the Examples section of International Publication No. 2016 / 017801 was pulverized once using a rotary mill (Fritsch, Rotor speed mill P-14) and twice using a jet mill (SEISHIN, Single track jet mill FS-4) at a pulverizing pressure of 0.6 MPa to obtain resin powder. Furthermore, the obtained resin powder was classified using a high-efficiency precision air classifier (Seishin, Classiel N-10) at a processing speed of 0.4 kg / hr to obtain the fluorinated copolymer (B-1). The obtained fluorinated copolymer (B-1) had a particle size D90 of 3.0 μm.

[0233] The molar ratio of each unit in the fluorinated copolymer (B-1) is NAH unit: TFE unit: PPVE unit = 0.1: 97.9: 2.0.

[0234] [Fluoropolymer (C-1)]

[0235] The "fluorinated copolymer (X1-1)" in the Example section of International Publication No. 2016 / 017801 was pulverized using a jet mill at a pulverizing pressure of 0.5 MPa and used as fluorinated copolymer (C-1). The resulting fluorinated copolymer (C-1) had a particle size D90 of 5.0 μm and a particle size D50 of 2-3 μm.

[0236] The molar ratio of each unit in the fluorinated copolymer (C-1) is NAH unit: TFE unit: PPVE unit = 0.1: 97.9: 2.0.

[0237] [Fluoropolymer (C-2)]

[0238] Fluorinated copolymer (C-2) was obtained by pulverizing “Fluorinated copolymer (X1-1)” in the Example section of International Publication No. 2016 / 017801 using a rotary mill. The particle size D90 of the obtained fluorinated copolymer (C-2) was 100 μm.

[0239] The molar ratio of each unit in the fluorinated copolymer (C-2) is NAH unit: TFE unit: PPVE unit = 0.1: 97.9: 2.0.

[0240] [Fluoropolymer (C-3)]

[0241] The fluorinated copolymer (X1-1) described in the Example section of International Publication No. 2016 / 017801 was pulverized using a jet mill at a pulverizing pressure of 0.55 MPa to obtain the fluorinated copolymer (C-3). The obtained fluorinated copolymer (C-3) had a particle size D90 of 4.5 μm and a particle size D50 of 1.7 μm.

[0242] In addition, the molar ratio of each unit in the fluorinated copolymer (C-3) is NAH unit: TFE unit: PPVE unit = 0.1: 97.9: 2.0.

[0243] [Example 1]

[0244] The components and mixing amounts shown in Table 1 were prepared, and the fluorinated copolymer composition was obtained by mixing with two rollers at room temperature for 10 minutes.

[0245] The obtained fluorinated copolymer composition was hot-pressed at 180°C for 20 minutes using a hydraulic press (model: SA-301 50T, manufactured by TESTER SANGYO CO., LTD., press head diameter: 180mm) to obtain O-rings (size: P-26) (one-time crosslinking).

[0246] Then, under a nitrogen atmosphere, the O-ring was heated at 90°C for 2 hours, followed by a 2-hour increase to 200°C and held for 4 hours. The temperature was then further increased to 305°C over 2 hours and heated at 305°C for 13 hours (secondary crosslinking). Finally, it was cooled to room temperature to obtain the O-ring of Example 1.

[0247] [Example 2~Example 4]

[0248] The O-rings in Examples 2 to 4 were changed to the fluorinated copolymers shown in the table. Otherwise, they were obtained by the same steps as in Example 1.

[0249] ·BOAP: 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, polyamine compound (crosslinking agent)

[0250] [Table 1]

[0251]

[0252] [Table 2]

[0253]

[0254] As shown in the table, it is confirmed that the effects of the present invention can be obtained if this composition is used.

[0255] Specifically, comparing Examples 1 and 2, in sections A and B, the weight reduction ratios of Examples 1 and 2 were the same. However, in section C, the weight reduction ratio of Example 1 was less than that of Example 2. That is, it was confirmed that when this cross-linked rubber article is used for a long time under plasma irradiation, the weight reduction ratio in section C after a specified time is suppressed compared to Example 2 of the prior art, i.e., it has a beneficial effect compared to the prior art. The effects of this invention are effects that are difficult for those skilled in the art to anticipate.

[0256] Furthermore, comparing Example 1 and Example 3, it can be seen that in any partition A to C, the weight reduction ratio is suppressed in Example 1 compared to Example 3.

[0257] Specifically, comparing Example 1 and Example 4, in partitions A and B, the weight reduction ratio of Example 1 is the same as that of Example 2. On the other hand, in partition C, the weight reduction ratio of Example 1 is less than that of Example 4.

[0258] It should be noted that the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2023-221261, filed on December 27, 2023, are incorporated herein as a disclosure of the specification of this invention.

Claims

1. A fluorinated copolymer composition comprising a fluorinated copolymer (A), a fluorinated copolymer (B), and a crosslinking agent, The fluorinated copolymer (A) has tetrafluoroethylene-based units and perfluoro(alkyl vinyl ether)-based units. The fluorinated copolymer (B) is a fluorinated copolymer different from the fluorinated copolymer (A), and contains units based on monomers having at least one functional group selected from the group represented by carboxyl groups and groups of formula (X), units based on tetrafluoroethylene, and units based on perfluorinated (alkyl vinyl ethers), and has a particle size D90 of less than 4.0 μm. Formula (X) *-CO-O-CO-* In equation (X), * represents the bonding position.

2. The fluorinated copolymer composition according to claim 1, wherein, The fluorinated copolymer (A) also contains units having nitrile groups. The content of the nitrile-containing unit is 0.05 to 5.0 mol% relative to all units of the fluorinated copolymer (A). The content of the tetrafluoroethylene-based unit relative to all units of the fluorinated copolymer (A) is 59.0~79.95 mol%. The content of the perfluorinated (alkyl vinyl ether)-based unit is 20.0 to 40.95 mol relative to all units of the fluorinated copolymer (A).

3. The fluorinated copolymer composition according to claim 1 or 2, wherein, The content of the monomer unit based on at least one functional group selected from the group consisting of a carboxyl group and a group represented by formula (X) is 0.01 to 3.0 mol% relative to all units of the fluorinated copolymer (B). The content of the tetrafluoroethylene-based unit relative to all units of the fluorinated copolymer (B) is 90-99.89 mol%. The content of the perfluorinated (alkyl vinyl ether)-based unit is 0.1 to 9.99 mol relative to all units of the fluorinated copolymer (B).

4. The fluorinated copolymer composition according to claim 1 or 2, wherein, The content of the fluorinated copolymer (B) is less than 50 parts by mass relative to 100 parts by mass of the fluorinated copolymer (A).

5. The fluorinated copolymer composition according to claim 1 or 2, wherein, The crosslinking agent is a compound having two or more amino groups. The content of the crosslinking agent is 0.3 to 10 parts by mass relative to 100 parts by mass of the fluorinated copolymer (A).

6. The fluorinated copolymer composition according to claim 1 or 2, wherein, The bulk density of the fluorinated copolymer (B) is less than 0.25 g / mL.

7. A fluorinated copolymer composition comprising a fluorinated copolymer (A), a fluorinated copolymer (B), and a crosslinking agent. The fluorinated copolymer (A) has tetrafluoroethylene-based units and perfluoro (alkyl vinyl ether)-based units; The fluorinated copolymer (B) is a fluorinated copolymer different from the fluorinated copolymer (A), and contains units based on monomers having at least one functional group selected from the group represented by carboxyl groups and groups of formula (X), units based on tetrafluoroethylene, and units based on perfluorinated (alkyl vinyl ethers). The fluorinated copolymer composition was tested in a vulcanization test at 180°C according to JIS K6296. 90 Less than 10 minutes Formula (X) *-CO-O-CO-* In equation (X), * represents the bonding position.

8. The fluorinated copolymer composition according to claim 7, wherein, The fluorinated copolymer (A) contains units having nitrile groups. The content of the nitrile-containing unit is 0.05 to 5.0 mol% relative to all units of the fluorinated copolymer (A). The content of the tetrafluoroethylene-based unit relative to all units of the fluorinated copolymer (A) is 59.0~79.95 mol%. The content of the perfluorinated (alkyl vinyl ether)-based unit is 20.0 to 40.95 mol relative to all units of the fluorinated copolymer (A).

9. The fluorinated copolymer composition according to claim 7 or 8, wherein, The content of the monomer unit based on at least one functional group selected from the group consisting of a carboxyl group and a group represented by formula (X) is 0.01 to 3.0 mol% relative to all units of the fluorinated copolymer (B). The content of the tetrafluoroethylene-based unit relative to all units of the fluorinated copolymer (B) is 90-99.89 mol%. The content of the perfluorinated (alkyl vinyl ether)-based unit is 0.1 to 9.99 mol relative to all units of the fluorinated copolymer (B).

10. The fluorinated copolymer composition according to claim 7 or 8, wherein, The content of the fluorinated copolymer (B) is less than 50 parts by mass relative to 100 parts by mass of the fluorinated copolymer (A).

11. The fluorinated copolymer composition according to claim 7 or 8, wherein, The crosslinking agent is a compound having two or more amino groups. The content of the crosslinking agent is 0.3 to 10 parts by mass relative to 100 parts by mass of the fluorinated copolymer (A).

12. The fluorinated copolymer composition according to claim 7 or 8, wherein, The bulk density of the fluorinated copolymer (B) is less than 0.25 g / mL.

13. A crosslinked rubber article obtained from the fluorinated copolymer composition of claim 1 or 7.

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