FLUOROCOPOLYMER COMPOSITION, CROSSLINKED PRODUCT THEREOF, AND COMPOUND

Abstract

Provided are: a fluorine-containing copolymer composition containing a fluorine-containing copolymer and a fluorine-containing compound having two maleimide groups; a cross-linked product of said composition; and a compound.

Description

[Technical field]

[0001] The present disclosure relates to a fluorine-containing copolymer composition and a crosslinked product thereof, and a compound. [Background technology]

[0002] Known fluorine-containing copolymers include vinylidene fluoride / hexafluoropropylene copolymers, tetrafluoroethylene / propylene copolymers, tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymers, etc. Crosslinked products obtained by crosslinking such fluorine-containing copolymers are used as rubbers.

[0003] For example, JP-A-2009-529070 describes crosslinking a composition containing a fluorocarbon polymer containing a unit derived from a monomer selected from vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, vinyl ether, and chlorotrifluoroethylene, a radical reaction initiator, a first curing aid selected from the group consisting of allyl cyanurate, allyl isocyanurate, methallyl cyanurate, and methallyl isocyanurate, and a second curing aid containing an organic compound containing at least one terminal alkene, the second curing aid being not a component of the group of the first curing aid. JP-A-2009-529070 describes the use of triallyl isocyanurate as the first curing aid in crosslinking the fluorocarbon polymer. JP-A-2009-529070 also describes N,N'-m-phenylene bismaleimide as the second curing aid.

[0004] Furthermore, JP 2012-180484 A describes that a compound having two maleimide groups is used as a monomer for producing a polymer. Summary of the Invention [Problem to be solved by the invention]

[0005] When triallyl isocyanurate described in JP-A-2009-529070 is used as a crosslinking aid, the compression set of the crosslinked product obtained is insufficient, and further improvement is required. Also, when N,N'-m-phenylene bismaleimide described in JP-A-2009-529070 is used as a crosslinking aid, the crosslinking speed tends to be slow. Furthermore, JP-A-2012-180484 describes a compound having two maleimide groups, but does not describe a crosslinking technique.

[0006] The present disclosure has been made in view of these circumstances, and the problem to be solved by one embodiment of the present invention is to provide a fluorocopolymer composition which is crosslinked at a high crosslinking rate and capable of giving a crosslinked product excellent in compression set. Another embodiment of the present invention is to provide a crosslinked product excellent in compression set. Another embodiment of the present invention is to provide a novel compound. [Means for solving the problem]

[0007] Specific means for solving the above problems include the following aspects. <1> A fluorine-containing copolymer composition comprising a fluorine-containing copolymer and a fluorine-containing compound having two maleimide groups. <2> The fluorine-containing compound having two maleimide groups is a compound represented by the following formula (1): <1> The fluorine-containing copolymer composition according to claim 1. [ka] In formula (1), R 1 is a divalent linking group having 1 to 30 carbon atoms and containing a fluorine atom. <3> R 1 is represented by the following formula (X): <2> The fluorine-containing copolymer composition according to claim 1. [ka] In formula (X), m is an integer of 0 to 8, when m is 0, L is a fluorinated alkylene group having 1 to 30 carbon atoms, a fluorinated cycloalkylene group having 3 to 20 carbon atoms, or a fluorinated arylene group having 5 to 20 carbon atoms; When m is 1 or more, L's are each independently an alkylene group having 1 to 30 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, an arylene group having 5 to 20 carbon atoms, a fluorinated alkylene group having 1 to 30 carbon atoms, a fluorinated cycloalkylene group having 3 to 20 carbon atoms, or a fluorinated arylene group having 5 to 20 carbon atoms, at least one of the multiple L's is a fluorinated alkylene group having 1 to 30 carbon atoms, a fluorinated cycloalkylene group having 3 to 20 carbon atoms, or a fluorinated arylene group having 5 to 20 carbon atoms, and each A's are independently a single bond or -O-. <4> The fluorine-containing compound having two maleimide groups has a main chain connecting the nitrogen atoms of the two maleimide groups, and the number of atoms constituting the main chain is 3 to 9. <1> ~ <3> Fluorine-containing copolymer composition according to any one of the above items. <5> The fluorine-containing compound having two maleimide groups has a fluorine atom content of 3 at % to 32 at %. <1> ~ <4> Fluorine-containing copolymer composition according to any one of the above items. <6> The fluorine-containing compound having two maleimide groups is represented by the following formula (1A) or formula (1B): <1> ~ <5> Fluorine-containing copolymer composition according to any one of the above items. [ka] In formula (1A), m1 is an integer of 0 to 6; 1 each independently represents a single bond or -O-. In formula (1B), m2 is an integer of 0 to 4, L 1 are each independently a perfluoro-o-phenylene group, a perfluoro-m-phenylene group, or a perfluoro-p-phenylene group; A 2 each independently represents a single bond or -O-. <7> The fluorine-containing compound having two maleimide groups is represented by the following formula (1C) or formula (1D): <1> ~ <6> Fluorine-containing copolymer composition according to any one of the above items. [ka] In formula (1C), p is an integer of 1 to 7. In formula (1D), q is an integer of 1 to 5. <8> the ratio of the content of the fluorine-containing compound having two maleimide groups to the content of the fluorine-containing copolymer is 0.01 to 0.1 on a mass basis; <1> ~ <7> Fluorine-containing copolymer composition according to any one of the above items. <9> The fluorine-containing copolymer has an iodine atom and contains a structural unit derived from tetrafluoroethylene and a structural unit derived from a perfluoroalkyl vinyl ether. <1> ~ <8> Fluorine-containing copolymer composition according to any one of the above items. <10> <1> ~ <9> 2. A crosslinked body obtained by crosslinking the fluorine-containing copolymer composition according to any one of 1 to 11. <11> A compound represented by the following formula (1A): [ka] In formula (1A), m1 is an integer of 0 to 6; 1 each independently represents a single bond or -O-. <12> The compound represented by formula (1A) is represented by the following formula (1C): <11> The compound according to claim 1, [ka] In formula (1C), p is an integer of 1 to 7. <13> p is 2, 4 or 6; <12> The compound according to claim 1, Effect of the Invention

[0008] According to the present disclosure, there is provided a fluorocopolymer composition which is crosslinked at a high crosslinking rate and which can give a crosslinked product having excellent compression set. Furthermore, according to the present disclosure, a crosslinked body having excellent compression set is provided. The present disclosure also provides novel compounds. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The fluorocopolymer composition and crosslinked product, as well as the compound, of the present disclosure will be described in detail below. In this specification, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively.

[0010] In this specification, the amount of each component in a composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified. As used herein, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0011] [Fluorine-containing copolymer composition] The fluorine-containing copolymer composition of the present disclosure contains a fluorine-containing copolymer and a fluorine-containing compound having two maleimide groups.

[0012] In the fluorine-containing copolymer composition of the present disclosure, the compatibility between the fluorine-containing copolymer and the fluorine-containing compound having two maleimide groups is high, so it is considered that the crosslinking reaction proceeds at a faster crosslinking rate than in the past. In addition, the fluorine-containing compound having two maleimide groups is difficult to self-polymerize, so it is considered that the crosslinking reaction proceeds at a faster crosslinking rate than in the past. Furthermore, the crosslinked body obtained by the crosslinking reaction between the fluorine-containing copolymer and the fluorine-containing compound having two maleimide groups has a stronger crosslinked structure than the crosslinked body obtained using the conventional crosslinking assistant, so it is considered to be excellent in compression set.

[0013] Each component contained in the fluorocopolymer composition of the present disclosure will be described below.

[0014] (Fluorine-containing compound having two maleimide groups) The fluorine-containing copolymer composition of the present disclosure contains a fluorine-containing compound having two maleimide groups. The term "fluorine-containing compound" refers to a compound having at least one fluorine atom therein.

[0015] The fluorine-containing compound having two maleimide groups is preferably a compound represented by the following formula (1), from the viewpoints of improving the crosslinking rate and obtaining a crosslinked product excellent in compression set.

[0016] [ka]

[0017] In formula (1), R 1 is a divalent linking group having 1 to 30 carbon atoms and containing a fluorine atom.

[0018] R 1 is preferably a divalent linking group composed of at least one fluorine atom, 1 to 30 carbon atoms, 0 to 100 hydrogen atoms, 0 to 10 nitrogen atoms, 0 to 20 oxygen atoms, and 0 to 20 sulfur atoms.

[0019] R 1 Examples of R include one group P selected from the group consisting of a divalent aliphatic group, a divalent aromatic group, and a divalent heterocyclic group, and a group in which at least two groups P are single-bonded together, in which at least one hydrogen atom is substituted with a fluorine atom. 1 represents at least two groups P selected from the group consisting of a divalent aliphatic group, a divalent aromatic group, and a divalent heterocyclic group, and is selected from the group consisting of -O-, -S-, -SO2-, -NR L -, -CO-, -COO-, -CONR L -, -SO3- and -SO2NR LIn the groups bonded to each other by at least one group Q selected from the group consisting of -, at least one hydrogen atom may be substituted with a fluorine atom. L represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. In particular, from the viewpoint of improving the crosslinking rate and obtaining a crosslinked product excellent in compression set, the group P is preferably at least one group selected from the group consisting of divalent aliphatic groups and divalent aromatic groups, and the group Q is preferably -O-.

[0020] Examples of the divalent aliphatic group include an alkylene group, an alkenylene group, and an alkynylene group. The divalent aliphatic group may be linear, branched, or cyclic. Of these, the divalent aliphatic group is preferably a linear alkylene group.

[0021] Examples of the divalent aromatic group include a phenylene group and a naphthylene group. Of these, the divalent aromatic group is preferably a phenylene group.

[0022] The heterocycle constituting the divalent heterocyclic group is preferably a 5-membered or 6-membered ring. The heterocycle may be a single ring or a condensed ring. Examples of the heterocycle include a pyridine ring, a piperidine ring, a furan ring, a thiophene ring, a pyrrole ring, a quinoline ring, a morpholine ring, an indole ring, an imidazole ring, a pyrazole ring, a carbazole ring, a phenothiazine ring, a phenoxazine ring, an indoline ring, a thiazole ring, a pyrazine ring, a thiadiazine ring, a benzoquinoline ring, and a thiadiazole ring.

[0023] The divalent aliphatic group and the divalent aromatic group may have a substituent. Examples of the substituent include halogen atoms other than fluorine atoms, cyano groups, nitro groups, hydroxy groups, aliphatic groups, aromatic groups, and heterocyclic groups. Examples of the aliphatic group, aromatic group, and heterocyclic group include the groups described above.

[0024] R 1 is preferably represented by the following formula (X).

[0025] [ka]

[0026] In formula (X), m is an integer of 0 to 8. When m is 0, L is a fluorinated alkylene group having 1 to 30 carbon atoms, a fluorinated cycloalkylene group having 3 to 20 carbon atoms, or a fluorinated arylene group having 5 to 20 carbon atoms. When m is 1 or more, L is each independently an alkylene group having 1 to 30 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, an arylene group having 5 to 20 carbon atoms, a fluorinated alkylene group having 1 to 30 carbon atoms, a fluorinated cycloalkylene group having 3 to 20 carbon atoms, or a fluorinated arylene group having 5 to 20 carbon atoms, at least one of the multiple Ls is a fluorinated alkylene group having 1 to 30 carbon atoms, a fluorinated cycloalkylene group having 3 to 20 carbon atoms, or a fluorinated arylene group having 5 to 20 carbon atoms, and each A is independently a single bond or -O-.

[0027] The term "fluorinated alkylene group" refers to an alkylene group in which at least one hydrogen atom bonded to a carbon atom is replaced with a fluorine atom. The term "fluorinated cycloalkylene group" refers to a cycloalkylene group in which at least one hydrogen atom bonded to a carbon atom is replaced with a fluorine atom. The term "fluorinated arylene group" refers to an arylene group in which at least one hydrogen atom bonded to a carbon atom is replaced with a fluorine atom.

[0028] In formula (X), m is preferably an integer of 0 to 6. When m is 0, L is a fluorinated alkylene group having 1 to 10 carbon atoms, or a fluorinated arylene group having 5 to 15 carbon atoms. When m is 1 or more, L is each independently an alkylene group having 1 to 10 carbon atoms, or an arylene group having 5 to 15 carbon atoms, a fluorinated alkylene group having 1 to 10 carbon atoms, or a fluorinated arylene group having 5 to 15 carbon atoms, and it is preferable that at least one of the multiple L's is a fluorinated alkylene group having 1 to 10 carbon atoms, or a fluorinated arylene group having 5 to 15 carbon atoms.

[0029] In formula (X), m is preferably an integer of 0 to 6. When m is 0, L is a perfluoroalkylene group having 1 to 10 carbon atoms, or a perfluoroarylene group having 5 to 15 carbon atoms. When m is 1 or more, L is each independently an alkylene group having 1 to 10 carbon atoms, an arylene group having 5 to 15 carbon atoms, a perfluoroalkylene group having 1 to 10 carbon atoms, or a perfluoroarylene group having 5 to 15 carbon atoms. It is more preferable that at least one of the multiple L's is a perfluoroalkylene group having 1 to 10 carbon atoms, or a perfluoroarylene group having 5 to 15 carbon atoms.

[0030] The term "perfluoroalkylene group" refers to an alkylene group in which all hydrogen atoms bonded to carbon atoms are replaced with fluorine atoms. The term "perfluoroarylene group" refers to an arylene group in which all hydrogen atoms bonded to carbon atoms are replaced with fluorine atoms.

[0031] The fluorine-containing compound having two maleimide groups is preferably represented by the following formula (1A) or formula (1B), from the viewpoints of further increasing the crosslinking rate and obtaining a crosslinked product with better compression set.

[0032] [ka]

[0033] In formula (1A), m1 is an integer of 0 to 6; 1 In formula (1B), m2 is an integer of 0 to 4, L 1 are each independently a perfluoro-o-phenylene group, a perfluoro-m-phenylene group, or a perfluoro-p-phenylene group; A 2 each independently represents a single bond or -O-.

[0034] In addition, the fluorine-containing compound having two maleimide groups is preferably represented by the following formula (1C) or (1D), from the viewpoint of further improving the crosslinking rate and obtaining a crosslinked product with better compression set.

[0035] [ka]

[0036] In formula (1C), p is an integer of 1 to 7. In formula (1D), q is an integer of 1 to 5.

[0037] Specific examples of the fluorine-containing compound having two maleimide groups include the following compounds. However, the fluorine-containing compound having two maleimide groups in the present disclosure is not limited thereto.

[0038] [ka]

[0039] [ka]

[0040] In the fluorine-containing compound having two maleimide groups, the number of atoms constituting the main chain linking the nitrogen atoms of the two maleimide groups is preferably 3 to 9. The number of atoms constituting the main chain linking the nitrogen atoms of the two maleimide groups is more preferably 4 or more. The number of atoms constituting the main chain linking the nitrogen atoms of the two maleimide groups is more preferably 8 or less. "The number of atoms constituting the main chain linking the nitrogen atoms of the two maleimide groups" means the number of atoms when tracing the shortest path between the two nitrogen atoms. For example, in the case of the above compound A1, the number of atoms constituting the main chain linking the nitrogen atoms of the two maleimide groups is 6, and in the case of the above compound A2, it is 4.

[0041] The fluorine-containing compound having two maleimide groups preferably has a fluorine atom content of 3 at% to 32 at%. The fluorine atom content is more preferably 7 at% or more, and even more preferably 12 at%. The fluorine atom content is more preferably 29 at% or less, and even more preferably 25 at% or less. The fluorine atom content is 19 F-NMR (fluorine-19 nuclear magnetic resonance), 1 H-NMR (proton nuclear magnetic resonance), 13 The number of fluorine atoms in the fluorine-containing compound can be calculated by analyzing the structure of the fluorine-containing compound using C-NMR (carbon-13 nuclear magnetic resonance) or the like and dividing the number of fluorine atoms in the fluorine-containing compound by the number of all atoms that constitute the fluorine-containing compound.

[0042] The fluorine atom contents of the compounds given as specific examples of the fluorine-containing compound having two maleimide groups are as follows: A1: 22 at%, A2: 14 at%, A3: 14 at%, A4: 21 at%, A5: 4 at%, A6: 20 at%, A7: 21 at%, A8: 27 at%, A9: 13 at%, and A10: 29 at%.

[0043] When the fluorine atom content of the fluorine-containing compound having two maleimide groups is within the above range, the compatibility with the fluorine-containing copolymer is high. As a result, the fluorine-containing compound having two maleimide groups and the fluorine-containing copolymer are crosslinked at a faster crosslinking rate. In addition, self-polymerization between the fluorine-containing compounds having two maleimide groups is unlikely to occur, and the crosslinking efficiency is excellent.

[0044] From the viewpoint of improving the crosslinking rate and obtaining a crosslinked product excellent in compression set, the content of the fluorine-containing compound having two maleimide groups is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, based on the total mass of the fluorine-containing copolymer composition. Also, the content of the fluorine-containing compound having two maleimide groups is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 7% by mass or less, based on the total mass of the fluorine-containing copolymer composition.

[0045] (Fluorine-containing copolymer) The fluorine-containing copolymer in the present disclosure is not particularly limited as long as it is a copolymer having at least one fluorine atom. Examples of monomers constituting the fluorine-containing copolymer include fluorine-containing monomers and hydrocarbon monomers. At least one of the monomers constituting the fluorine-containing copolymer is a fluorine-containing monomer. The fluorine-containing copolymer may contain only one type of structural unit derived from a fluorine-containing monomer, or may contain two or more types in combination. In addition, the fluorine-containing copolymer may contain only one type of structural unit derived from a hydrocarbon monomer, or may contain two or more types in combination.

[0046] Examples of fluorine-containing monomers include tetrafluoroethylene (hereinafter also referred to as "TFE"), vinylidene fluoride (hereinafter also referred to as "VDF"), chlorotrifluoroethylene (hereinafter also referred to as "CTFE"), hexafluoropropylene (hereinafter also referred to as "HFP"), perfluoroalkyl vinyl ether (hereinafter also referred to as "PAVE"), a monomer having at least one fluorine atom and two polymerizable unsaturated groups (hereinafter also referred to as "DVE"), and 2,3,3,3-tetrafluoro-1-propene.

[0047] Examples of the hydrocarbon monomer include olefins such as ethylene, propylene, isobutene, and 1-butene.

[0048] From the viewpoint of improving the crosslinking rate and obtaining a crosslinked product excellent in compression set, the PAVE is preferably a compound represented by formula (A). CF2=CF-OR f1 (A) In formula (A), R f1 R represents a perfluoroalkyl group having 1 to 10 carbon atoms. f1 From the viewpoint of superior polymerization reactivity, the carbon number of R is preferably 8 or less, more preferably 6 or less, further preferably 5 or less, and particularly preferably 3 or less. f1The number of carbon atoms in the perfluoroalkyl group is preferably at least 1. The perfluoroalkyl group may be linear or branched.

[0049] Examples of PAVE include perfluoro(methyl vinyl ether) (hereinafter referred to as "PMVE"), perfluoro(ethyl vinyl ether) (hereinafter also referred to as "PEVE"), perfluoro(propyl vinyl ether) (hereinafter also referred to as "PPVE"), and perfluoro(methoxyethyl vinyl ether). Among them, PAVE is preferably PMVE or PPVE in view of its superior polymerization reactivity.

[0050] From the viewpoints of improving the crosslinking rate and obtaining a crosslinked product excellent in compression set, the DVE is preferably a compound represented by formula (B). (CR 21 R 22 =CR 23 )2R 24 (B) In formula (B), R 21 , R 22 and R 23 R each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 24 represents a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the end or between the carbon-carbon bonds of a perfluoroalkylene group having 1 to 10 carbon atoms. 21 , multiple R 22 and multiple R 23 may be the same or different, but are preferably the same.

[0051] R 21 , R 22 and R 23 From the viewpoint of improving the crosslinking rate, it is preferable that each of them independently be a fluorine atom or a hydrogen atom, it is more preferable that all of them are fluorine atoms or all of them are hydrogen atoms, and it is even more preferable that all of them are fluorine atoms.

[0052] R 24R may be linear, branched or cyclic, preferably linear or branched, more preferably linear. 24 The number of carbon atoms in R is preferably 2 or more, and more preferably 3 or more. 24 The number of carbon atoms is preferably 8 or less, more preferably 7 or less, even more preferably 6 or less, and particularly preferably 5 or less.

[0053] R 24 From the viewpoint of improving the crosslinking rate, R is preferably a group having an ether oxygen atom at the end of a perfluoroalkylene group having 1 to 10 carbon atoms or between carbon-carbon bonds. 24 The number of ether oxygen atoms in R is preferably 6 or less, more preferably 3 or less. 24 The number of ether oxygen atoms in R is preferably 1 or more. 24 The number of ether oxygen atoms in R is more preferably 1 or 2. 24 The etheric oxygen atom in R 24 It is preferred that the nucleotide sequence is located at the end of the nucleotide sequence.

[0054] From the viewpoint of further improving the crosslinking rate and obtaining a crosslinked product with better compression set, the DVE is more preferably a compound represented by formula (C) or a compound represented by formula (D). (CF2=CF)2R 31 (C) (CH2=CH)2R 41 (D)

[0055] In formula (C), R 31 represents a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between the carbon-carbon bonds of a perfluoroalkylene group having 1 to 10 carbon atoms.

[0056] In formula (D), R 41 represents a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between the carbon-carbon bonds of a perfluoroalkylene group having 1 to 10 carbon atoms.

[0057] Specific examples of the compound represented by formula (C) include CF2=CFO(CF2)2OCF=CF2, CF2=CFO(CF2)3OCF=CF2, CF2=CFO(CF2)4OCF=CF2, and CF2=CFO(CF2)6OCF=CF 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, CF 2=CFO(CF2O)3(CF(CF3)CF2O)2CF=CF2, CF2=CFOCF2CF(CF3)O(CF2)2OCF(CF3)CF2OCF=CF2 and CF2=CFOCF2CF2O(CF2O)2CF2CF2OCF=CF2.

[0058] Of the compounds represented by formula (C), CF2=CFO(CF2)3OCF=CF2 (hereinafter also referred to as "C3DVE") or CF2=CFO(CF2)4OCF=CF2 (hereinafter also referred to as "C4DVE") is preferred, and C3DVE is more preferred.

[0059] Specific examples of the compound represented by formula (D) include CH2=CH(CF2)2CH=CH2, CH2=CH(CF2)4CH=CH2 and CH2=CH(CF2)6CH=CH2.

[0060] Of the compounds represented by formula (D), CH2=CH(CF2)6CH=CH2 (hereinafter also referred to as "C6DV") is preferred.

[0061] When DVE is copolymerized with other monomers, some of the polymerizable double bonds at the ends of DVE react during polymerization to produce a branched fluorocopolymer. Branched fluorocopolymers have lower compression set and better sealing properties than linear fluorocopolymers.

[0062] The fluorine-containing copolymer of the present disclosure may contain other structural units than the structural units derived from the above monomers. Examples of the other structural units include structural units derived from a compound having a fluorine atom and a nitrile group, structural units derived from a perfluorooxyalkylvinyl ether, and structural units derived from a compound having a fluorine atom and a halogen atom other than a fluorine atom.

[0063] The compound having a fluorine atom and a nitrile group is preferably a compound represented by formula (E). CR 51 R 52 =CR 53 -R 54 -CN(E) In formula (E), R 51 , R 52 and R 53 R each independently represents a hydrogen atom, a fluorine atom or a methyl group. 54 represents a perfluoroalkylene group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between the carbon-carbon bonds of a perfluoroalkylene group having 1 to 10 carbon atoms.

[0064] R 51 , R 52 and R 53 are each independently preferably a fluorine atom or a hydrogen atom, more preferably all are fluorine atoms or all are hydrogen atoms, and further preferably all are fluorine atoms.

[0065] R 54 R may be linear, branched or cyclic, preferably linear or branched, more preferably linear. 54 The number of carbon atoms in R is preferably 2 or more, and more preferably 3 or more. 54 The number of carbon atoms is preferably 8 or less, more preferably 7 or less, even more preferably 6 or less, and particularly preferably 5 or less.

[0066] R 54R is preferably a group having an ether oxygen atom at the end of a perfluoroalkylene group having 1 to 10 carbon atoms or between carbon-carbon bonds. 54 The number of ether oxygen atoms in R is preferably 1 to 3, and more preferably 1 or 2. 54 The etheric oxygen atom in R 54 It is preferred that the nucleotide sequence is located at the end of the nucleotide sequence.

[0067] Specific examples of the compound represented by formula (E) include CF2=CFOCF2CF(CF3)OCF2CF2CN, CF2=CFO(CF2)5CN, CF2=CFOCF2CF2CF2OCF(CF3)CN and CF2=CFO(CF2)3CN.

[0068] The perfluorooxyalkyl vinyl ether is preferably a compound represented by formula (F). CF2=CF-OR f2 (F) In formula (F), R f2 R represents a perfluoroalkyl group having 1 to 8 carbon atoms and containing 1 to 5 etheric oxygen atoms. f2 The carbon number of the group is preferably 1 to 6, and particularly preferably 1 to 5.

[0069] Specific examples of the compound represented by formula (F) include perfluoro(3,6-dioxa-1-heptene), perfluoro(3,6-dioxa-1-octene), and perfluoro(5-methyl-3,6-dioxa-1-nonene).

[0070] The compound having a fluorine atom and a halogen atom other than a fluorine atom is preferably a compound containing either an iodine atom or a bromine atom, or both an iodine atom and a bromine atom.

[0071] Specific examples of the compound having a fluorine atom and a halogen atom other than a fluorine atom include CF2=CFBr, CH2=CHCF2CF2Br, CF2=CFOCF2CF2I, CF2=CFOCF2CF2Br, CF2=CFOCF2CF2CH2I, CF2=CFOCF2CF2CH2Br, CF2=CFOCF2CF(CF3)OCF2CF2CH2I and CF2=CFOCF2CF(CF3)OCF2CF2CF2Br.

[0072] Examples of fluorine-containing copolymers that do not contain structural units derived from hydrocarbon monomers include TFE / PAVE copolymers, VDF / HFP copolymers, TFE / VDF / HFP copolymers, VDF / HFP / PAVE copolymers, VDF / CTFE copolymers, and TFE / PAVE / DVE copolymers. Examples of fluorine-containing copolymers that contain structural units derived from hydrocarbon monomers include TFE / propylene copolymers, TFE / propylene / VDF copolymers, TFE / propylene / CTFE copolymers, and ethylene / HFP copolymers.

[0073] From the viewpoint of improving the crosslinking rate and obtaining a crosslinked body excellent in compression set, the fluorine-containing copolymer in the present disclosure is preferably at least one selected from the group consisting of TFE / PAVE copolymer, VDF / HFP copolymer, TFE / VDF / HFP copolymer, VDF / HFP / PAVE copolymer, TFE / PAVE / DVE copolymer, TFE / propylene copolymer and TFE / propylene / VDF copolymer, more preferably TFE / PAVE copolymer, TFE / PAVE / DVE copolymer, TFE / propylene copolymer or TFE / propylene / VDF copolymer, further preferably TFE / PAVE copolymer or TFE / PAVE / DVE copolymer, and most preferably TFE / PAVE / DVE copolymer. That is, the fluorine-containing copolymer in the present disclosure preferably contains a structural unit derived from TFE and a structural unit derived from PAVE, more preferably contains a structural unit derived from TFE, a structural unit derived from PAVE and a structural unit derived from DVE.

[0074] From the viewpoint of improving the crosslinking rate and obtaining a crosslinked product excellent in compression set, the content of the constitutional unit derived from TFE is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 63 mol% or more, based on the total mass of the fluorocopolymer. Also, the content of the constitutional unit derived from TFE is preferably 81 mol% or less, more preferably 79 mol% or less, and even more preferably 77 mol% or less.

[0075] From the viewpoint of improving the crosslinking rate and obtaining a crosslinked product excellent in compression set, the content of the PAVE-derived structural unit is preferably 19 mol% or more, more preferably 21 mol% or more, and even more preferably 23 mol% or more, based on the total mass of the fluorocopolymer. Also, the content of the PAVE-derived structural unit is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 37 mol% or less.

[0076] From the viewpoint of improving the crosslinking rate and obtaining a crosslinked product excellent in compression set, the content of the structural unit derived from DVE is preferably 0.01 mol% or more, more preferably 0.03 mol% or more, and even more preferably 0.05 mol% or more, based on the total mass of the fluorocopolymer. Also, the content of the structural unit derived from DVE is preferably 1.0 mol% or less, more preferably 0.6 mol% or less, and even more preferably 0.03 mol% or less.

[0077] The content of structural units derived from DVE is calculated based on the amount of DVE used in the production of the fluorocopolymer (amount of DVE used). Here, "amount of DVE used" is the amount of DVE added to the polymerization vessel (amount of DVE charged) minus the amount of DVE that was not polymerized. It is believed that the unpolymerized DVE is contained in the filtrate obtained after coagulating the latex after polymerization and extracting the fluorocopolymer, and in the filtrate remaining after washing the latex. For example, the amount can be measured by measuring the fluoride ions in the filtrate with an ion chromatograph measuring device.

[0078] In addition, the content of the structural unit derived from TFE and the content of the structural unit derived from PAVE are 19 It is calculated using F-NMR (fluorine-19 nuclear magnetic resonance). Specifically, 19 The molar ratio of the TFE-derived structural units and the PAVE-derived structural units in the fluorocopolymer is calculated by F-NMR (fluorine-19 nuclear magnetic resonance).Then, the content of the TFE-derived structural units and the content of the PAVE-derived structural units are calculated based on the value obtained by subtracting the content (mol%) of the DVE-derived structural units from 100 mol% and the above molar ratio.

[0079] The fluorine-containing copolymer preferably contains an iodine atom or a bromine atom, more preferably an iodine atom, which functions as a crosslinking point that reacts with the fluorine-containing compound having two maleimide groups.

[0080] The iodine atom or bromine atom can be introduced into the fluorine-containing copolymer by using an iodine compound or a bromo compound as a chain transfer agent described later when producing the fluorine-containing copolymer. The iodine atom or bromine atom can also be introduced into the fluorine-containing copolymer by copolymerizing a compound having an iodine atom or a bromine atom with another monomer.

[0081] The content of iodine or bromine atoms is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, based on the total mass of the fluorine-containing copolymer. The content of iodine or bromine atoms is preferably 5.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less. When the content of iodine or bromine atoms is within the above range, the crosslinking speed is faster and a crosslinked body with better compression set can be obtained.

[0082] The fluorine-containing copolymer preferably has an iodine atom and contains a structural unit derived from TFE and a structural unit derived from PAVE.

[0083] The storage modulus G' of the fluorocopolymer is preferably 450 kPa or more, more preferably 470 kPa or more. When the storage modulus G' is 450 kPa or more, a crosslinked product having a more excellent compression set can be obtained.

[0084] The storage modulus G' of the fluorocopolymer is preferably at most 650 kPa, more preferably at most 630 kPa, and even more preferably at most 600 kPa, from the viewpoint of processability.

[0085] The storage modulus G' is an index of the average molecular weight, and a high value indicates a high molecular weight, and a low value indicates a low molecular weight. The storage modulus G' is a value measured in accordance with ASTM D5289 and ASTM D6204. The storage modulus G' is measured, for example, using a dynamic viscoelasticity device (product name "RPA2000", manufactured by Alpha Technologies) under conditions of a temperature of 100°C, an amplitude of 0.5 degrees, and a frequency of 50 times / min.

[0086] For details of the components other than those mentioned above used in the production of the fluorine-containing copolymer and the production method of the fluorine-containing copolymer, the method described in paragraphs 0019 to 0034 of WO 2010 / 082633 can be referred to.

[0087] The ratio of the content of the fluorine-containing compound having two maleimide groups to the content of the fluorine-containing copolymer is preferably 0.01 to 0.1 by mass. The ratio is more preferably 0.02 or more by mass, and even more preferably 0.03 or more by mass. The ratio is more preferably 0.08 or less by mass, and even more preferably 0.07 or less by mass.

[0088] (Other ingredients) The fluorine-containing copolymer composition of the present disclosure may contain, in addition to the fluorine-containing copolymer and the fluorine-containing compound having two maleimide groups, at least one selected from the group consisting of a crosslinking agent and a catalyst.

[0089] Examples of the crosslinking agent include organic peroxides, polyols, and polyamines. From the viewpoint of obtaining a crosslinked body having excellent compression set, the fluorocopolymer composition of the present disclosure preferably contains a crosslinking agent. From the viewpoint of improving the crosslinking rate, the crosslinking agent is preferably an organic peroxide.

[0090] Examples of organic peroxides include dialkyl peroxides, α,α'-bis(tert-butylperoxy)-p-diisopropylbenzene, α,α'-bis(tert-butylperoxy)-m-diisopropylbenzene, benzoyl peroxide, tert-butylperoxybenzene, and 2,5-dimethyl-2,5-di(benzoylperoxy)hexane.

[0091] Examples of dialkyl peroxides include 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxyperoxide, tert-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne, tert-butylperoxymaleic acid, and diisopropyl peroxydicarbonate.

[0092] When the fluorocopolymer composition contains a crosslinking agent, the content of the crosslinking agent is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, based on 100 parts by mass of the fluorocopolymer. The content of the crosslinking agent is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less. When the content of the crosslinking agent is within the above range, the obtained crosslinked body has an excellent balance between strength and elongation.

[0093] The catalyst may include organotin compounds, such as tetramethyltin, tetra(n-butyl)tin, and tetraphenyltin.

[0094] When the fluorine-containing copolymer composition contains a catalyst, the content of the catalyst is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, based on 100 parts by mass of the fluorine-containing copolymer. The content of the catalyst is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less. When the content of the catalyst is within the above range, the obtained crosslinked body has an excellent balance between strength and elongation.

[0095] The fluorine-containing copolymer composition may further contain other components other than those described above, within the scope of not impairing the effects of the present disclosure. Examples of other components include crosslinking aids (e.g., triallyl cyanurate, triallyl isocyanurate, and trimethallyl isocyanurate), acid acceptors (e.g., fatty acid esters, fatty acid metal salts, and oxides of divalent metals (magnesium oxide, calcium oxide, zinc oxide, lead oxide, etc.)), fillers and reinforcing materials (e.g., carbon black, barium sulfate, calcium metasilicate, calcium carbonate, titanium oxide, silicon dioxide, clay, and talc), scorch retarders (e.g., phenolic hydroxyl group-containing compounds such as bisphenol A; quinones such as hydroquinone; and 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).

[0096] When the fluorocopolymer composition contains other components, the total content of the other components is preferably more than 0 part by mass, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the fluorocopolymer. The total content of the other components is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 15 parts by mass or less.

[0097] The method for preparing the fluorine-containing copolymer composition includes a method of mixing the above-mentioned components. The components can be mixed using a rubber mixer such as a roll, a kneader, a Banbury mixer or an extruder.

[0098] Alternatively, the mixture may be molded after the components are mixed together to obtain a mixture. Methods for molding the mixture include compression molding, injection molding, extrusion molding, calendar molding, and a method in which the mixture is dissolved in a solvent and then dipped or coated on a substrate or the like to form the mixture.

[0099] [Crosslinked body] The crosslinked product of the present disclosure is a crosslinked product obtained by crosslinking the fluorocopolymer in the above-mentioned fluorocopolymer composition.

[0100] Methods for crosslinking the fluorocopolymer in the fluorocopolymer composition include a method involving heating and a method involving irradiation with radiation, and a method in which the fluorocopolymer composition is crosslinked by heating is preferred.

[0101] Examples of the crosslinking method by heating include heat press crosslinking, steam crosslinking and hot air crosslinking. The crosslinking method may be appropriately selected in consideration of the shape of the fluorocopolymer composition, the use of the crosslinked product, etc.

[0102] The heating conditions are preferably 100° C. to 400° C. for 1 second to 24 hours.

[0103] After the fluorocopolymer composition is heated (after the primary crosslinking), it may be further heated to cause secondary crosslinking. By carrying out the secondary crosslinking, the mechanical properties, compression set and other properties of the obtained crosslinked product can be improved.

[0104] The heating conditions for the secondary crosslinking are preferably 80° C. to 350° C. for 30 minutes to 48 hours.

[0105] Examples of the method for crosslinking the fluorocopolymer by a method other than heating include a method in which the fluorocopolymer composition is irradiated with radiation to crosslink the fluorocopolymer. Examples of the radiation to be irradiated include electron beams and ultraviolet rays.

[0106] From the viewpoint of excellent rubber properties, the hardness (Shore-A) of the crosslinked body is preferably 65 or more, more preferably 68 or more, and even more preferably 70 or more. Moreover, the hardness (Shore-A) of the crosslinked body is preferably 100 or less, more preferably 90 or less, and even more preferably 85 or less.

[0107] The hardness (Shore-A) of the crosslinked body is a value measured using a type A durometer in accordance with JIS K6253-3:2012, using a plate-shaped molded product (thickness 1 mm) of the crosslinked body.

[0108] The tensile strength (tensile strength at break) of the crosslinked product is preferably 1 MPa or more, more preferably 5 MPa or more, in terms of excellent rubber properties, and is preferably 50 MPa or less, more preferably 35 MPa or less.

[0109] The tensile elongation (elongation at break) of the crosslinked product is preferably 100% or more, more preferably 120% or more, from the viewpoint of excellent rubber properties, and is preferably 1000% or less, more preferably 600% or less.

[0110] The tensile strength and tensile elongation of the crosslinked body are values ​​measured by a method conforming to JIS K 6251:2010 (corresponding international standard ISO 37:2005).

[0111] The compression set of the crosslinked body after being held at 250°C for 70 hours is preferably 70% or less, and more preferably 65% ​​or less, because the fluorocopolymer is well crosslinked and the crosslinked body has excellent shape recovery after pressure application.

[0112] The compression set of the crosslinked body after being held at 250°C for 168 hours is preferably 85% or less, and more preferably 82% or less, because the fluorocopolymer is well crosslinked and the crosslinked body has excellent shape recovery after pressure application.

[0113] The compression set of the crosslinked body after being held at 250°C for 336 hours is preferably 97% or less, and more preferably 93% or less, because the fluorocopolymer is well crosslinked and the crosslinked body has excellent shape recovery after pressure is applied.

[0114] The lower limit of the compression set of the crosslinked body after being held at 250°C for 70 hours is preferably 0%, and it is most preferable that the compression set of the crosslinked body after being held at 250°C for 70 hours is 0%.

[0115] The compression set of the crosslinked body is a value measured in accordance with JIS K 6262: 2013. However, the test piece used to measure the compression set is an O-ring test piece according to P26 of JIS B 2401-1: 2012.

[0116] The above-mentioned physical properties of the crosslinked body can be adjusted, for example, by the production conditions of the above-mentioned fluorocopolymer (e.g., the order of addition, number of times and amount of each monomer), the type and content of each component contained in the above-mentioned fluorocopolymer composition, and the production conditions of the crosslinked rubber body (e.g., crosslinking conditions).

[0117] The crosslinked body of the present disclosure is suitable for materials such as O-rings, sheets, gaskets, oil seals, diaphragms, V-rings, etc. The crosslinked body of the present disclosure can also be used in applications such as heat-resistant and chemical-resistant sealing materials, heat-resistant and oil-resistant sealing materials, electric wire coating materials, sealing materials for semiconductor devices, corrosion-resistant rubber paints, sealing materials for urea-based grease, rubber paints, adhesive rubbers, hoses, tubes, calendar sheets (rolls), sponges, rubber rolls, oil drilling components, heat dissipation sheets, solution crosslinked bodies, rubber sponges, bearing seals, linings, insulating sheets for automobiles, insulating sheets for electronic devices, rubber bands for watches, packings for endoscopes, bellows hoses, packings / valves for water heaters, fenders, fibers / nonwoven fabrics (protective clothing, etc.), board sealants, rubber gloves, stators for uniaxial eccentric screw pumps, parts for urea SCR systems, vibration isolators, vibration dampers, sealing agents, additives for other materials, and toys.

[0118] [Compound] The compounds of the present disclosure are represented by formula (1A).

[0119] [ka]

[0120] In formula (1A), m1 is an integer of 0 to 6; 1 each independently represents a single bond or -O-.

[0121] The compound represented by formula (1A) is preferably represented by the following formula (1C).

[0122] [ka]

[0123] In formula (1C), p is an integer of 1 to 7. p is preferably 2, 4 or 6, and more preferably 4.

[0124] The compounds of the present disclosure can be prepared, for example, by the following method.

[0125] [ka]

[0126] First, dicarboxylic acid (11), which is a raw material for producing the compound represented by formula (1A), is amidated to obtain diamide (12). The method for amidation is not particularly limited, and a known method can be used. For example, dicarboxylic acid (11) can be converted to an ester or acid halide, and then reacted with ammonia to obtain diamide (12).

[0127] Next, diamide (12) is reduced to obtain diamine (13). The reduction method is not particularly limited, and a known method can be used. For example, diamide (12) is reduced using sodium borohydride as a reducing agent in the presence of aluminum chloride, and then hydrochloric acid is added to obtain the hydrochloride of diamine (13). Diamine (13) can be obtained by neutralizing the hydrochloride of diamine (13) with a base. An example of the base is sodium hydroxide. Diamide (12) may be obtained from a commercial product.

[0128] Next, the diamine (13) and maleic anhydride are subjected to an imidization reaction to obtain a compound represented by formula (1A). The method of imidization is not particularly limited, and a known method can be used. For example, the imidization reaction is performed using a silylating agent and a Lewis acid catalyst. Examples of the silylating agent include 1,1,1,3,3,3-hexamethyldisilazane, chlorotrimethylsilane, methanesulfonic acid trimethylsilyl ester, and N,N'-bis(trimethylsilyl)urea. Examples of the Lewis acid catalyst include zinc chloride, zinc bromide, aluminum halide, tin halide, titanium halide, magnesium halide, and trifluoroborane etherate complex.

[0129] The compound of the present disclosure is useful as a crosslinking aid, particularly as a crosslinking aid in crosslinking a fluorine-containing copolymer. EXAMPLES

[0130] Hereinafter, the present disclosure will be described more specifically with reference to examples. However, the present disclosure is not limited to the following examples as long as it does not depart from the gist of the disclosure.

[0131] [Example 1] <Production of Fluorine-Containing Copolymer> After degassing a 20L stainless steel pressure reactor equipped with an anchor blade, 8.2L of ultrapure water, 733g of a 30% solution of C2F5OCF2CF2OCF2COONH4 as an emulsifier, 10g of CF2=CFO(CF2)3OCF=CF2(C3DVE), and 15.9g of a 5% aqueous solution of disodium hydrogen phosphate 12-hydrate were charged and the gas phase was replaced with nitrogen. While stirring at a speed of 375 rpm using an anchor blade, 198g of tetrafluoroethylene (TFE) and 454g of perfluoro(methyl vinyl ether) (PMVE) were pressed into the vessel, and the internal temperature was raised to 80°C. The pressure inside the reactor was 0.90MPa [gauge]. 40mL of a 1% aqueous solution of ammonium persulfate (APS) was added to start polymerization. The addition ratio of the monomers injected before the start of polymerization (hereinafter also referred to as "initial added monomers"), expressed in molar ratio, was TFE:PMVE:C3DVE=41.74:57.64:0.62.

[0132] As the polymerization progressed, when the pressure inside the reactor dropped to 0.89 MPa [gauge], TFE was injected and the pressure inside the reactor was increased to 0.90 MPa [gauge]. This was repeated, and every time 80 g of TFE was injected, 62 g of PMVE was also injected. In addition, 7.0 g of 1,4-diiodoperfluorobutane was injected into the reactor from the ampoule together with 50 mL of ultrapure water when 60 g of TFE was injected. When the polymerization rate began to slow down, a 3% by mass aqueous solution of APS was appropriately added.

[0133] When the total mass of the post-added TFE reached 1200g, the addition of the post-added monomer was stopped, and the temperature in the reactor was cooled to 10°C to terminate the polymerization reaction. This resulted in a latex containing a fluorine-containing copolymer. The polymerization time was 360 minutes. The total mass of each post-added monomer was 1200g for TFE and 868g for PMVE, which was converted to a molar ratio of TFE:PMVE=68:32.

[0134] Nitric acid (special grade, manufactured by Kanto Chemical Co., Ltd.) was dissolved in ultrapure water to prepare a 3% by mass aqueous solution of nitric acid. The latex was added to the 3% by mass aqueous solution of nitric acid to coagulate the fluorine-containing copolymer. The solution containing the fluorine-containing copolymer was filtered, washed with ultrapure water, and vacuum-dried at 50°C and 10 kPa to obtain a white fluorine-containing copolymer. The content (molar ratio) of each structural unit in the obtained fluorine-containing copolymer was structural unit derived from TFE / structural unit derived from PMVE / structural unit derived from C3DVE=71.40 / 28.43 / 0.17. The content of iodine atoms in the fluorine-containing copolymer was 0.10% by mass. The content of iodine atoms was calculated using an apparatus combining an automatic sample combustion apparatus, a pretreatment device for ion chromatography (product name "AQF-100", manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and an ion chromatograph.

[0135] In addition, when the filtrate obtained by the filtration carried out when obtaining the fluorocopolymer from the latex was filtered through a disk filter and the obtained liquid was analyzed by an ion chromatograph, fluoride ions of 3% by mass or more relative to the amount of C3DVE charged were not detected. Therefore, it was assumed that all the C3DVE used in the charging was polymerized, and the content of C3DVE units relative to the total units in the polymer was calculated based on the amount of C3DVE charged.

[0136] <Production of fluorine-containing compound A1 (C4-BMI) having two maleimide groups>

[0137] [ka]

[0138] In a 1L four-neck flask equipped with a Dimroth, diethylene glycol dimethyl ether (332 mL) and aluminum (III) chloride (15.4 g, 115 mmol) were charged under a nitrogen atmosphere and stirred for 15 minutes. The reaction solution was ice-cooled, sodium borohydride (13.1 g, 346 mmol) was charged, and stirred for 40 minutes. A diethylene glycol dimethyl ether suspension (53 mL) of 2,2,3,3,4,4,5,5-octafluorohexanediamide (25.0 g, 86.8 mmol) was dropped into the reaction solution, and the mixture was stirred for 40 minutes. The external temperature was set to 110°C, and the mixture was stirred for 3 hours. The reaction solution was cooled at room temperature, and water (175 mL) was dropped into the reaction solution. Next, a 4.5% by mass aqueous solution of sodium hydroxide (142 mL) was dropped into the reaction solution. The reaction solution was transferred to a separatory funnel, diisopropyl ether (623 mL) was added, and the mixture was stirred to separate the organic layer 1. Diisopropyl ether (623 mL) was added to the aqueous phase, and the organic layer 2 was separated by re-extraction. Diisopropyl ether (623 mL) was added to the aqueous phase again, and the organic layer 3 was separated by re-extraction. Organic layers 1, 2, and 3 were combined, dried over anhydrous sodium sulfate, and insoluble matter was removed by filtration under reduced pressure. The filtrate was ice-cooled, and a 1 mol / L diethyl ether solution of hydrogen chloride (175 mL) was added dropwise. After 1000 mL of the supernatant was removed by decantation, acetonitrile (541 mL) was added and stirred at room temperature for 40 minutes. The precipitated solid was collected by filtration under reduced pressure and dried under reduced pressure at an external temperature of 50°C to obtain 2,2,3,3,4,4,5,5-octafluoro-1,6-hexamethylenediamine hydrochloride (OHDA·2HCl, 22.5 g, 65.5 mmol). The structure of OHDA·2HCl was confirmed from the following data. 1 H-NMR (DMSO-d6): δ(ppm)9.12(s,6H), 3.85(t,4H,J=17.1Hz)

[0139] [ka]

[0140] Next, OHDA·2HCl (48.8 g, 142 mmol), chloroform (488 mL), and 10% aqueous sodium hydroxide solution (488 mL) were charged into a 2 L separatory funnel, stirred, and the organic layer was separated. The obtained organic layer was washed with saturated saline (166 mL), and the organic layer was separated. Anhydrous sodium sulfate was added to the organic layer, stirred, and then insoluble matter was removed by filtration under reduced pressure. The obtained filtrate was concentrated under reduced pressure using an evaporator to obtain 2,2,3,3,4,4,5,5-octafluoro-1,6-hexamethylenediamine (OHDA). The yield was 33.7 g, and the yield was 90%. The structure of OHDA was confirmed from the following data. 1 H-NMR (CDCl3): δ(ppm)3.26(dt,4H,J=7.68,15.4Hz), 1.29(s,4H) 19 F-NMR(CDCl3):δ(ppm)-122(m,4F), -124(m,4F)

[0141] [ka]

[0142] Next, maleic anhydride (33.9 g, 346 mmol) and toluene (648 mL) were added to a 2 L glass flask equipped with a Dimroth filter under a nitrogen atmosphere and stirred at room temperature. Next, a solution consisting of OHDA (30.0 g, 115 mmol) and toluene (408 mL) was added, and the mixture was stirred at an external temperature of 30 ° C. for 2 hours. A toluene solution (168 mL) of zinc bromide (78.2 g, 347 mmol) and 1,1,1,3,3,3-hexamethyldisilazane (76.1 g, 472 mmol) was added to the reaction solution, and the mixture was stirred at an external temperature of 100 ° C. for 2 hours. After cooling the reaction solution, 2 mol / L hydrochloric acid (500 mL) was added and insoluble matter 1 was removed by filtration under reduced pressure. The filtrate was separated and the organic layer was separated. The obtained organic layer was washed with a saturated aqueous sodium bicarbonate solution (500 mL). After dehydration with anhydrous sodium sulfate, the insoluble matter was removed by filtration under reduced pressure to obtain an organic layer 1. The insoluble matter 1 and ethyl acetate (1000 mL) obtained above were charged into a 2 L flask and heated until the internal temperature reached 60°C. After cooling at room temperature, saturated aqueous sodium bicarbonate solution (500 mL) was added. After stirring, the organic layer was separated. The obtained organic layer was dehydrated with anhydrous sodium sulfate, and the insoluble matter was removed by filtration under reduced pressure to obtain organic layer 2. Organic layer 1 and organic layer 2 were combined and concentrated under reduced pressure using an evaporator. The obtained concentrate was purified by silica gel column chromatography (mobile phase: ethyl acetate) to obtain a crude product of C4-BMI (39.4 g). Diethyl ether (80 mL) and chloroform (80 mL) were added to the crude product of C4-BMI, and the mixture was heated to reflux, then cooled on ice, and the insoluble C4-BMI was collected by filtration under reduced pressure. The yield was 33.5 g, and the yield was 69%. The structure of C4-BMI was confirmed from the following data. 1 H-NMR (CDCl3): δ (ppm) 6.82 (s, 4H), 4.19 (t, 4H, J=15.4Hz). 19 F-NMR (CDCl3): δ(ppm) -117(s,4F), -124(t,4F,J=15.3Hz). The fluorine content of compound A1 (C4-BMI) is 22 at %.

[0143] <Production of Fluorine-Containing Copolymer Composition> 100 parts by mass of the above fluorocopolymer, 1 part by mass of 2,5-di(tert-butylperoxy)hexane (product name "Perhexa 25B", manufactured by NOF Corporation) as a crosslinking agent, and 5 parts by mass of the above C4-BMI as a crosslinking aid were mixed and kneaded with a two-roll mill to obtain fluorocopolymer composition 1.

[0144] <Production of Crosslinked Body> The fluorocopolymer composition was heat-molded at 170°C for 20 minutes to obtain a plate-shaped primary crosslinked product having dimensions of 100 mm length x 60 mm width x 1 mm thickness. The sheet was then heated at 250°C for 24 hours in a nitrogen atmosphere to obtain a plate-shaped secondary crosslinked product.

[0145] [Example 2] A fluorocopolymer composition 2 was obtained in the same manner as in Example 1, except that the compound A1 (C4-BMI) in Example 1 was changed to the following compound A4 (FB-BMI). In addition, the fluorocopolymer composition 2 was used to obtain A crosslinked body was obtained in the same manner as in Example 1. The fluorine content of compound A4 (FB-BMI) was 21 at %.

[0146] [ka]

[0147] [Example 3] 100 parts by mass of the above fluorocopolymer, 0.5 parts by mass of 2,5-di(tert-butylperoxy)hexane (product name "Perhexa 25B", manufactured by NOF Corp.) as a crosslinking agent, and 0.5 parts by mass of triallyl isocyanurate (TAIC) as a crosslinking aid were mixed and kneaded with a two-roll mill to obtain a fluorocopolymer composition 3. Moreover, a crosslinked product was obtained using the fluorocopolymer composition 3 in the same manner as in Example 1.

[0148] [Example 4] 100 parts by mass of the above fluorocopolymer, 1 part by mass of 2,5-di(tert-butylperoxy)hexane (product name "Perhexa 25B", manufactured by NOF Corp.) as a crosslinking agent, and 6 parts by mass of N,N'-1,3-phenylenedimaleimide (BMI) as a crosslinking aid were mixed and kneaded with a two-roll mill to obtain a fluorocopolymer composition 4. Moreover, a crosslinked product was obtained using the fluorocopolymer composition 4 in the same manner as in Example 1.

[0149] The hardness, tensile strength, tensile elongation and compression set of the crosslinked product were measured. The vulcanization time for obtaining the crosslinked product was also measured. The measurement methods are as follows. The measurement results are shown in Table 1. Examples 1 and 2 correspond to working examples, and Examples 3 and 4 correspond to comparative examples.

[0150] (hardness) The plate-shaped crosslinked body (thickness 1 mm) was punched out with a No. 4 dumbbell to prepare three test pieces. The test pieces were used to measure hardness (Shore-A) using a type A durometer in accordance with JIS K6253-3:2012. The test was performed using three test pieces, and the arithmetic average of the measured values ​​of the three test pieces was recorded. The measurement device used was an automatic rubber hardness tester (product name: Digitest, manufactured by H. Burleith Co.).

[0151] (tensile strength, tensile elongation) The plate-shaped crosslinked body (thickness 1 mm) was punched out with a No. 4 dumbbell to prepare three test pieces. The prepared test pieces were used to measure the tensile strength and tensile elongation in accordance with JIS K6251:2010 (corresponding international standard ISO 37:2005). Each test was performed using three test pieces, and the arithmetic average of the measured values ​​of the three test pieces was recorded. The measurement was performed using a tensile tester with data processing (product name "Quick Reader TS-2530", manufactured by Ueshima Seisakusho Co., Ltd.).

[0152] (Compression set) Three P26 O-ring test pieces were prepared in accordance with JIS B 2401-1:2012. The test pieces were used to calculate the compression set (%) when held at 250°C for 70 hours, 168 hours, and 336 hours in accordance with JIS K 6262:2013. The compression set was calculated based on the following formula. The test was performed using three test pieces, and the arithmetic average of the values ​​calculated for the three test pieces was recorded. The closer the compression set is to 0%, the better the recovery of the crosslinked body, that is, the better the crosslinking. Compression set (%) = (original thickness of test specimen - thickness of test specimen 30 minutes after removal from compression device) ÷ (original thickness of test specimen - thickness of spacer) x 100

[0153] (Vulcanization time) The fluorine-containing copolymer composition was heated at 170°C for 20 minutes. The 2% vulcanization time (t2) and the 90% vulcanization time (t90) were measured. The smaller t2 and t90 indicate a faster crosslinking rate. The measuring device used was a dynamic viscoelasticity device (product name "RPA2000", manufactured by Alpha Technologies).

[0154] [Table 1]

[0155] As shown in Table 1, in Examples 1 and 2, the compression set when held at 250° C. for 70 hours was small, and the vulcanization time was also short.

[0156] On the other hand, in Example 3 in which TAIC was used as a crosslinking aid, the compression set was large when held at 250° C. for 70 hours, and in Example 4 in which BMI was used as a crosslinking aid, the vulcanization time was long.

[0157] The disclosure of Japanese Patent Application No. 2020-028034, filed on February 21, 2020, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A fluorine-containing copolymer and a fluorine-containing compound having two maleimide groups, The fluorine-containing compound having two maleimide groups is a compound represented by the following formula (1): The content of the fluorine-containing compound having two maleimide groups is 0.1% by mass to 15% by mass based on the total mass of the fluorine-containing copolymer composition. Fluorine-containing copolymer composition. 【change】 In formula (1), R １ is a divalent linking group represented by the following formula (X). 【Chemistry 2】 In formula (X), m is an integer of 0 to 8; when m is 0, L is a fluorinated alkylene group having 1 to 30 carbon atoms, a fluorinated cycloalkylene group having 3 to 20 carbon atoms, or a fluorinated arylene group having 5 to 20 carbon atoms; When m is 1 or more, L's are each independently an alkylene group having 1 to 30 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, an arylene group having 5 to 20 carbon atoms, a fluorinated alkylene group having 1 to 30 carbon atoms, a fluorinated cycloalkylene group having 3 to 20 carbon atoms, or a fluorinated arylene group having 5 to 20 carbon atoms, at least one of the multiple L's is a fluorinated alkylene group having 1 to 30 carbon atoms, a fluorinated cycloalkylene group having 3 to 20 carbon atoms, or a fluorinated arylene group having 5 to 20 carbon atoms, and each A's are independently a single bond or -O-.

2. The fluorine-containing copolymer composition according to claim 1, wherein the fluorine-containing compound having two maleimide groups has a main chain connecting the nitrogen atoms of the two maleimide groups of 3 to 9 atoms.

3. 3. The fluorine-containing copolymer composition according to claim 1, wherein the fluorine-containing compound having two maleimide groups has a fluorine atom content of 3 at % to 32 at %.

4. The fluorine-containing copolymer composition according to any one of claims 1 to 3, wherein the fluorine-containing compound having two maleimide groups is represented by the following formula (1A) or formula (1B): 【Chemistry 3】 In formula (1A), m1 is an integer of 0 to 6; １ each independently represents a single bond or --O--. In formula (1B), m2 is an integer of 0 to 4; L １ each independently represents a perfluoro-o-phenylene group, a perfluoro-m-phenylene group, or a perfluoro-p-phenylene group; A ２ each independently represents a single bond or --O--.

5. The fluorine-containing copolymer composition according to any one of claims 1 to 4, wherein the fluorine-containing compound having two maleimide groups is represented by the following formula (1C) or formula (1D): 【Chemistry 4】 In formula (1C), p is an integer from 1 to 7; In formula (1D), q is an integer of 1 to 5.

6. The fluorine-containing copolymer composition according to any one of claims 1 to 5, wherein a ratio of a content of the fluorine-containing compound having two maleimide groups to a content of the fluorine-containing copolymer is from 0.01 to 0.1 on a mass basis.

7. The fluorine-containing copolymer composition according to any one of claims 1 to 6, wherein the fluorine-containing copolymer has an iodine atom and comprises a structural unit derived from tetrafluoroethylene and a structural unit derived from a perfluoroalkyl vinyl ether.

8. A crosslinked product obtained by crosslinking the fluorocopolymer composition according to any one of claims 1 to 7.

9. A compound represented by the following formula (1A): 【Chemistry 5】 In formula (1A), m1 is an integer of 0 to 6; １ each independently represents a single bond or --O--.

10. The compound represented by formula (1A) is the compound according to claim 9, which is represented by the following formula (1C): 【Chemistry 6】 In formula (1C), p is an integer from 1 to 7.

11. The compound of claim 10, wherein p is 2, 4 or 6.

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