JP2017193682A - Elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastomer composition which has high crosslinking reactivity and is capable of providing a crosslinked product excellent in heat resistance, compression set characteristics, and alkali resistance.SOLUTION: The elastomer composition contains: a fluorine-containing elastic copolymer (a) having iodine atoms and having a constituent unit based on tetrafluoroethylene and a constituent unit based on propylene; and a perfluoroelastomer (b) having a hydrogen atom content of 0.1 mass% or less. The mass ratio [(a)/(b)] of the fluorine-containing elastic copolymer (a) to the perfluoroelastomer (b) is 1/99-99/1.SELECTED DRAWING: None

Description

  The present invention relates to an elastomer composition.

Fluorine-containing elastic copolymers have excellent heat resistance, chemical resistance, oil resistance, weather resistance, and other characteristics, making them suitable for use in harsh environments where hydrocarbon polymers cannot withstand. .
Examples of the fluorinated elastic copolymer include vinylidene fluoride / hexafluoropropylene copolymer (FKM), tetrafluoroethylene / propylene copolymer (FEPM), and tetrafluoroethylene / perfluoro (alkyl vinyl ether). A copolymer (FFKM) and the like are known.
In order to improve the mechanical properties (strength, elongation, compression set characteristics, etc.) of the fluorinated elastic copolymer, the fluorinated elastic copolymer is crosslinked to form a crosslinked product.

  However, in general, the fluorinated elastic copolymer has poor crosslinking reactivity, and particularly, the crosslinking reactivity of a perfluoroelastomer such as a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer is low. Moreover, the cross-linked product of vinylidene fluoride / hexafluoropropylene copolymer does not have sufficient alkali resistance. Tetrafluoroethylene / propylene copolymers do not have sufficient heat resistance and low temperature characteristics.

Patent Document 1 proposes a fluorine-containing elastomer composition containing a tetrafluoroethylene / propylene copolymer and a perfluoroelastomer such as a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer. The fluorine-containing elastomer composition is said to be excellent in cross-linking reactivity and excellent in heat resistance and compression set characteristics of the cross-linked product.
Patent Documents 2 to 3 propose tetrafluoroethylene / propylene copolymers in which polymerization is performed in the presence of a specific chain transfer agent having an iodine atom, and an iodine atom is contained at the molecular chain terminal. The tetrafluoroethylene / propylene copolymer is excellent in cross-linking reactivity and is excellent in heat resistance, chemical resistance, compression set characteristics, and the like of the cross-linked product.

International Publication No. 2007/119834 International Publication No. 2009/119202 International Publication No. 2010/053056

In the technique of Patent Document 1, alkali resistance, particularly alkali resistance under high temperature conditions is not sufficient.
In the technique of Patent Document 2, the low temperature characteristics are still not sufficient.

Accordingly, a first object of the present invention is to provide an elastomer composition that has a high crosslinking reactivity and is capable of obtaining a crosslinked product having excellent heat resistance, compression set characteristics, and alkali resistance.
The second object of the present invention is to provide an elastomer composition from which a crosslinked product excellent in low temperature characteristics and alkali resistance can be obtained.

In order to achieve the above object, the present invention employs the following configuration.
[1] A fluorine-containing elastic copolymer (a) having an iodine atom and having a structural unit based on tetrafluoroethylene and a structural unit based on propylene, and perfluoro having a hydrogen atom content of 0.1% by mass or less Containing an elastomer (b),
An elastomer composition having a mass ratio [(a) / (b)] of 1/99 to 99/1 between the fluorinated elastic copolymer (a) and the perfluoroelastomer (b).
[2] The perfluoroelastomer (b) is a structural unit based on tetrafluoroethylene and CF ₂ ═CF—O—R ^f (wherein R ^f has 1 carbon atom which may have an etheric oxygen atom). The elastomer composition according to [1], which has a structural unit based on ˜20 perfluoroalkyl groups.
[3] A fluorine-containing elastic copolymer (a) having an iodine atom and having a structural unit based on tetrafluoroethylene and a structural unit based on propylene, a structural unit based on hexafluoropropylene, and a structural unit based on vinylidene fluoride Containing a fluorinated elastic copolymer (c) (excluding the fluorinated elastic copolymer (a)),
The elastomer composition whose mass ratio [(a) / (c)] of the said fluorine-containing elastic copolymer (a) and the said fluorine-containing elastic copolymer (c) is 1/99-99/1.
[4] The fluorinated elastic copolymer (a) is based on at least one monomer selected from the group consisting of monomers represented by the following formula (I), (II) or (III): The elastomer composition according to any one of [1] to [3], further comprising a structural unit.
^{CR 1 R 2 = CR 3 -R} 4 -CR 5 = CR 6 R 7 ··· (I)
^{CR 8 R 9 = CR 10 -OCO} -R 11 -COO-CR 12 = CR 13 R 14 ··· (II)
CR ¹⁵ R ¹⁶ = CR ¹⁷ COOCH = CH ₂ (III)
(Wherein R ¹ , R ² , R ³ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁷ are each independently a hydrogen atom, A fluorine atom or a methyl group, wherein R ⁴ and R ¹¹ are each independently an alkylene group having 1 to 10 carbon atoms which may contain an etheric oxygen atom, or 1 to 1 carbon atom which may contain an etheric oxygen atom; 10 represents a fluoroalkylene group, and R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may contain an etheric oxygen atom.)

According to the elastomer composition [1], it is possible to provide an elastomer composition that has a high crosslinking reactivity and is capable of obtaining a crosslinked product having excellent heat resistance, compression set characteristics, and alkali resistance.
According to the elastomer composition [3], it is possible to provide an elastomer composition from which a crosslinked product having excellent low-temperature characteristics and alkali resistance can be obtained.

The meanings of the following terms in this specification are as follows.
“Monomer” means a compound having a polymerizable unsaturated bond. Examples of the polymerizable unsaturated bond include a double bond between carbon atoms (C═C), a triple bond (C≡C), and the like, and a double bond is preferable.
“Structural unit” means a unit derived from a monomer formed by polymerization of the monomer. The structural unit may be a unit directly formed by a monomer polymerization reaction, or may be a unit in which a part of the unit is converted into another structure by treating the polymer.
The “polymer” is a concept including a homopolymer and a copolymer, and may be a homopolymer or a copolymer.
The “fluorinated elastic copolymer” is a fluorinated copolymer having no melting point, also referred to as a fluororubber or a fluorinated elastomer.

In the following, tetrafluoroethylene is TFE, hexafluoropropylene is HFP, vinylidene fluoride is VdF, chlorotrifluoroethylene is CTFE, perfluoro (alkyl vinyl ether) is PAVE, perfluoro (methyl vinyl ether) is PMVE, perfluoro ( (Propyl vinyl ether) is described as PPVE, ethylene as E, and propylene as P.
A copolymer having a structural unit based on TFE and a structural unit based on P as an essential structural unit, and may further have another structural unit as necessary is referred to as “TFE / P copolymer”. Also described. The same applies to other copolymers having different essential structural units.
A copolymer comprising a structural unit based on TFE and a structural unit based on P is also referred to as a “TFE / P copolymer”. The same applies to other copolymers having different essential structural units.

<< Elastomer Composition of First Aspect >>
The elastomer composition of the first aspect of the present invention (hereinafter also referred to as “elastomer composition (1)”) contains the following fluorinated elastic copolymer (a) and perfluoroelastomer (b).

<Fluorine-containing elastic copolymer (a)>
The fluorinated elastic copolymer (a) is a fluorinated elastic copolymer having an iodine atom and having a structural unit based on TFE and a structural unit based on P.

The iodine atom in the fluorinated elastic copolymer (a) may be at the terminal of the copolymer (polymer chain), at a side group, or at both of them. From the viewpoint of crosslinking reactivity, it is preferably at least at the end of the polymer chain. Here, the terminal of the polymer chain is a concept including both the terminal of the main chain and the terminal of the branched chain.
The content of iodine atoms in the fluorinated elastic copolymer (a) is preferably from 0.01 to 5.0% by mass, preferably from 0.05 to 2%, based on the total mass of the fluorinated elastic copolymer (a). 0.0 mass% is more preferable, and 0.05 to 1.0 mass% is most preferable. When the content of iodine atoms is in the above range, the crosslinking reactivity is further improved, and the mechanical properties of the crosslinked product are further improved.

In the fluorinated elastic copolymer (a), the molar ratio of the structural unit based on TFE and the structural unit based on P [the structural unit based on TFE / the structural unit based on P] is preferably 30/70 to 99/1. 30/70 to 70/30 are more preferable, and 40/60 to 60/40 are more preferable. Within this range, the mechanical properties, heat resistance, chemical resistance (alkali resistance, etc.), oil resistance, and weather resistance of the crosslinked product are more excellent.
The total amount of the structural unit based on TFE and the structural unit based on P is preferably 99 mol% or more with respect to the total of all the structural units constituting the fluorinated elastic copolymer (a).

  The fluorinated elastic copolymer (a) may further have structural units based on monomers other than TFE and P, if necessary. Examples of other monomers include the following monomer (m1) and monomer (m2).

The monomer (m1) is at least one monomer selected from the group consisting of monomers represented by the following formula (I), (II) or (III).
When the monomer (m1) is copolymerized with TFE and P, the polymerizable double bonds at both ends of the monomer (m1) react during the polymerization, and a fluorinated elastic copolymer having a branched chain is obtained. can get.
If the fluorinated elastic copolymer (a) further has a constitutional unit based on the monomer (m1), a machine such as crosslinking reactivity, tensile strength of the crosslinked product and compression set at high temperature Excellent physical properties.

^{CR 1 R 2 = CR 3 -R} 4 -CR 5 = CR 6 R 7 ··· (I)
^{CR 8 R 9 = CR 10 -OCO} -R 11 -COO-CR 12 = CR 13 R 14 ··· (II)
CR ¹⁵ R ¹⁶ = CR ¹⁷ COOCH = CH ₂ (III)
(Wherein R ¹ , R ² , R ³ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁷ are each independently a hydrogen atom, A fluorine atom or a methyl group, wherein R ⁴ and R ¹¹ are each independently an alkylene group having 1 to 10 carbon atoms which may contain an etheric oxygen atom, or 1 to 1 carbon atom which may contain an etheric oxygen atom; 10 represents a fluoroalkylene group, and R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may contain an etheric oxygen atom.)

  Examples of the monomer represented by the formula (I) include vinyl groups having or without etheric oxygen at both ends of an alkylene group or fluoroalkylene group having 1 to 10 carbon atoms. , A compound to which a group independently selected from an allyl group and a butenyl group is bonded. Examples of the case where etheric oxygen is present include divinyl ether, allyl vinyl ether, butenyl vinyl ether, fluoro (divinyl ether), fluoro (allyl vinyl ether), fluoro (butenyl vinyl ether) and the like.

In the formula (I), it is preferable that R ¹ , R ² , R ³ , R ⁵ , R ⁶ and R ⁷ are each independently a fluorine atom or a hydrogen atom from the viewpoint of enhancing crosslinking reactivity and heat resistance. R ¹ , R ² , R ³ , R ⁵ , R ⁶ and R ⁷ are more preferably all fluorine atoms.
The alkylene group or fluoroalkylene group for R ⁴ may be linear or branched, and is preferably linear. The number of carbon atoms of R ⁴ is preferably 2-8, more preferably 3-7, more preferably 3-6, particularly preferably 3-5. The number of etheric oxygen atoms in R ⁴ is preferably 0-3, 1-2 is more preferable. When these are suitable R ⁴ , mechanical properties such as tensile strength of the cross-linked product and compression set characteristics at high temperatures are more excellent.
R ⁴ is preferably a fluoroalkylene group and particularly preferably a perfluoroalkylene group from the viewpoint of heat resistance and suppression of polymer coloring.
Preferable specific examples of the monomer represented by the formula (I) include 1,4-butanediol divinyl ether, CF ₂ ═CFO (CF ₂ ) ₃ OCF═CF ₂ , CF ₂ ═CFO (CF ₂ ) ₄ OCF═CF ₂ , CH ₂ ═CH (CF ₂ ) ₆ CH═CH _{2 and the} like.

Examples of the monomer represented by the formula (II) include divinyl ester, allyl vinyl ester, and butenyl vinyl ester.
In the formula (II), R ⁸ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ and R ¹⁴ are preferably hydrogen atoms.
Examples of R ¹¹ include the same as R ⁴ . The same applies to the preferred range of the number of carbon atoms. The number of etheric oxygen atoms in R ¹¹ is preferably 0 to 1, and more preferably 0.
Preferable specific examples of the monomer represented by the formula (II) include divinyl adipate.

In the formula (III), R ¹⁶ and R ¹⁷ are preferably hydrogen atoms.
Preferable specific examples of the formula (III) include vinyl crotonate and vinyl methacrylate, and vinyl crotonate is particularly preferable.

A monomer (m1) may be used individually by 1 type, and may use 2 or more types together.
When the fluorinated elastic copolymer (a) has a structural unit based on the monomer (m1), the content of the structural unit based on the monomer (m1) constitutes the fluorinated elastic copolymer (a). 0.01-2 mol% is preferable, 0.01-1 mol% is more preferable, and 0.01-0.5 mol% is more preferable with respect to the total (100 mol%) of all the structural units to perform. When it is at least the lower limit of the above range, the cross-linking reactivity is excellent, and the mechanical properties such as tensile strength of the cross-linked product and compression set at high temperature are even more excellent. When it is not more than the upper limit of the above range, it is possible to reliably prevent or further reduce cracking when a stress such as bending is applied at a high temperature while maintaining the excellent physical properties of the crosslinked product.

The monomer (m2) is a monomer other than TFE, P and the monomer (m1).
The monomer (m2) is not particularly limited as long as it is copolymerizable with TFE and P. For example, HFP, VdF, CTFE, PAVE, vinyl fluoride, pentafluoropropylene, perfluorocyclobutene, (perfluoroalkyl) ethylenes (e.g. _{CH 2 = CHCF 3, CH 2} = CHCF 2 CF 3, CH 2 = CHCF 2 CF 2 CF 3, CH 2 = CHCF 2 CF 2 CF 2 CF 3, CH 2 = CHCF 2 CF 2 CF 2 CF ₂ CF ₃ etc.) fluorine-containing monomers; E, α-olefins such as isobutylene and pentene, vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, vinyl acetate, vinyl propionate, butyric acid Vinyl, vinyl caproate, vinyl caprylate Non-fluorine-containing monomers such as vinyl esters; and the like. These monomers may be used individually by 1 type, and may use 2 or more types together. Among the above, PAVE is preferable.

Examples of PAVE include CF ₂ ═CF—O—R ^f (wherein R ^f is a C 1-20 perfluoroalkyl group which may have an etheric oxygen atom).
The perfluoroalkyl group for R ^f may be linear or branched. 1-8 are preferable, as for the carbon atom number of a perfluoroalkyl group, 1-6 are more preferable, 1-5 are more preferable, and 1-3 are especially preferable.
When the perfluoroalkyl group has an etheric oxygen atom, the perfluoroalkyl group may have one etheric oxygen atom or two or more. The etheric oxygen atom is an oxygen atom (—O—) existing between a carbon atom and a carbon atom. Therefore, when the perfluoroalkyl group of R ^f has an etheric oxygen atom, the lower limit of each range of the number of carbon atoms of R ^f is 2.
Specific examples of PAVE include PMVE, perfluoro (ethyl vinyl ether), PPVE, perfluoro (3,6-dioxa-1-heptene), perfluoro (3,6-dioxa-1-octene), perfluoro (5 -Methyl-3,6-dioxa-1-nonene) and the like. These monomers may be used individually by 1 type, and may use 2 or more types together. Among these, PMVE is preferable.

A monomer having an iodine atom may be used as the monomer (m2). When a monomer having an iodine atom is copolymerized, an iodine atom is introduced into a side group of the fluorinated elastic copolymer (a).
Examples of the monomer having an iodine atom include iodoethylene, 4-iodo-3,3,4,4-tetrafluoro-1-butene, 2-iodo-1,1,2,2-tetrafluoro-1- Vinyloxyethane, 2-iodoethyl vinyl ether, allyl iodide, 1,1,2,3,3,3-hexafluoro-2-iodo-1- (perfluorovinyloxy) propane, 3,3,4,5,5,5 -Hexafluoro-4-iodopentene, iodotrifluoroethylene, 2-iodoperfluoro (ethyl vinyl ether), etc. are mentioned.

A monomer (m2) may be used individually by 1 type, and may use 2 or more types together.
When the fluorinated elastic copolymer (a) has a structural unit based on the monomer (m2), the content of the structural unit based on the monomer (m2) constitutes the fluorinated elastic copolymer (a). 0.001 to 2.0 mol% is preferable, 0.01 to 1.0 mol% is more preferable, and 0.01 to 0.5 mol% is particularly preferable with respect to the total (100 mol%) of all the structural units. preferable.

As the fluorinated elastic copolymer (a), a copolymer composed of structural units of any combination of the following (X1) to (X8) is preferable. Any one of these copolymers may be used alone, or two or more thereof may be used in combination.
Since the cross-linking reactivity of the fluorinated elastic copolymer (a) is excellent, and the mechanical properties, heat resistance, chemical resistance (alkali resistance, etc.), oil resistance and weather resistance of the cross-linked product are further improved, (X1) , (X2), (X4), (X5), (X6), (X8) are more preferred, (X1), (X5) are more preferred, and (X8) is particularly preferred.

(X1): A combination of a structural unit based on TFE and a structural unit based on P.
(X2): A combination of a structural unit based on TFE, a structural unit based on P, and a structural unit based on VdF.
(X3): A combination of a structural unit based on TFE, a structural unit based on P, and a structural unit based on PPVE.
(X4): A combination of a structural unit based on TFE, a structural unit based on P, and a structural unit based on PMVE.
(X5): A combination of a structural unit based on TFE, a structural unit based on P, and a structural unit based on CR ¹ R ² = CR ³ -R ⁴ -CR ⁵ = CR ⁶ R ⁷ .
(X6): The combination of the structural units based on TFE, and structural units based on ^P, a structural unit based on the ^{CR 1 R 2 = CR 3 -R} 4 -CR 5 = CR 6 R 7, and structural units based on VdF .
(X7): A combination of a structural unit based on TFE, a structural unit based on P, a structural unit based on CR ¹ R ² = CR ³ -R ⁴ -CR ⁵ = CR ⁶ R ^7, and a structural unit based on PPVE .
(X8): The combination of the structural units based on TFE, and structural units based on ^P, a structural unit based on the ^{CR 1 R 2 = CR 3 -R} 4 -CR 5 = CR 6 R 7, and structural units based on PMVE .

The copolymer composition in (X1) to (X8) is preferably the following molar ratio. When the molar ratio is as follows, the cross-linking reactivity of the copolymer is further improved, and the mechanical properties, heat resistance, chemical resistance (alkali resistance, etc.), oil resistance, and weather resistance of the cross-linked product are further improved.
(X1): Structural unit based on TFE / Structural unit based on P = 40/60 to 60/40 (molar ratio).
(X2): Structural unit based on TFE / Structural unit based on P / Structural unit based on VdF = 40 to 59/59 to 40/1 to 10 (molar ratio).
(X3): Structural unit based on TFE / Structural unit based on P / Structural unit based on PPVE = 30 to 60/10 to 40/10 to 40 (molar ratio).
(X4): Structural unit based on TFE / Structural unit based on P / Structural unit based on PMVE = 30 to 60/10 to 40/10 to 40 (molar ratio).
(X5): Structural unit based on TFE / Structural unit based on P / CR ¹ R ² = CR ³ -R ⁴ -CR ⁵ = Structural unit based on CR ⁶ R ⁷ = 30 to 60/10 to 40 / 0.01 ~ 3 (molar ratio).
(X6): Structural unit based on TFE / Structural unit based on P / CR ¹ R ² = CR ³ -R ⁴ -CR ⁵ = Structural unit based on CR ⁶ R ⁷ / Structural unit based on VdF = 30-60 / 10 -40 / 0.01-3 / 1-10 (molar ratio).
(X7): Structural unit based on TFE / Structural unit based on P / CR ¹ R ² = CR ³ -R ⁴ -CR ⁵ = Structural unit based on CR ⁶ R ⁷ / Structural unit based on PPVE = 30-60 / 10 -40 / 0.01-3 / 10-40 (molar ratio).
(X8): Structural unit based on TFE / Structural unit based on P / CR ¹ R ² = CR ³ −R ⁴ −CR ⁵ = Structural unit based on CR ⁶ R ⁷ / Structural unit based on PMVE = 30 to 60/10 -40 / 0.01-3 / 10-40 (molar ratio).

The Mooney viscosity of the fluorinated elastic copolymer (a) is preferably from 10 to 200, more preferably from 20 to 180, and even more preferably from 30 to 170. Mooney viscosity is a measure of molecular weight, and a large molecular weight indicates a large molecular weight, and a small molecular weight indicates a small molecular weight. When the Mooney viscosity is within the above range, the processability of the fluorinated elastic copolymer and the mechanical properties of the crosslinked product are improved.
Mooney viscosity is a value measured according to JIS K6300-1: 2013.

The storage shear modulus G ′ of the fluorinated elastic copolymer (a) is preferably from 100 kPa to 600 kPa, more preferably from 200 kPa to 500 kPa, and even more preferably from 200 kPa to 400 kPa. A larger storage shear modulus G ′ indicates a higher molecular weight of the polymer and a higher density of molecular chain entanglement.
The storage shear modulus G ′ is a value measured at a temperature of 100 ° C., an amplitude of 0.5 degrees, and a frequency of 50 times / minute according to ASTM D5289 and D6204.

The glass transition temperature (hereinafter referred to as Tg) of the fluorinated elastic copolymer (a) is preferably 5 ° C. or less, more preferably −10 to 5 ° C., and further preferably −10 to 0 ° C. If Tg is not more than the above upper limit value, the low temperature characteristics are more excellent.
Tg is a value measured by the method described in Examples described later.

The fluorinated elastic copolymer (a) includes, for example, a radical polymerization initiator and an iodo compound represented by the formula RI ₂ (wherein R is an alkylene group or a perfluoroalkylene group having 3 or more carbon atoms). Can be produced by a production method in which TFE, P, and at least one selected from the group consisting of the monomer (m1) and the monomer (m2) are copolymerized if necessary.
Since the iodo compound functions as a chain transfer agent, when each monomer is copolymerized in the presence of the iodo compound, an iodine atom can be bonded to the main chain terminal of the fluorinated elastic copolymer. When the monomer (m1) is copolymerized, a fluorinated elastic copolymer having a branched chain is obtained, and iodine atoms can be similarly bonded to the ends of the branched chain. Therefore, the polymer chain end having an iodine atom may be a main chain end or a branched chain end.
Production of the fluorinated elastic copolymer (a) by the above production method can be carried out by utilizing the methods disclosed in International Publication No. 2009/119202, International Publication No. 2010/053056, and the like.

<Perfluoroelastomer (b)>
The perfluoroelastomer (b) is a perfluoroelastomer having a hydrogen atom content of 0.1% by mass or less.
Examples of the perfluoroelastomer (b) include an elastic copolymer having a structural unit based on TFE and a structural unit based on PAVE (hereinafter also referred to as “perfluoroelastomer (b1)”).

As PAVE, in terms of mechanical properties and heat resistance of the crosslinked product, CF ₂ = CF—O—R ^f (wherein R ^f has 1 to 20 carbon atoms which may have an etheric oxygen atom). A perfluoroalkyl group). That is, the perfluoroelastomer (b1) is preferably an elastic copolymer having a structural unit based on TFE and a structural unit based on CF ₂ ═CF—O—R ^f .
Examples of CF ₂ ═CF—O—R ^f include the same as those mentioned for the monomer (m2), and preferred embodiments are also the same.

In the perfluoroelastomer (b1), the molar ratio of the structural unit based on TFE and the structural unit based on PAVE [the structural unit based on TFE / the structural unit based on PAVE] is preferably 40/60 to 90/10, 50-80 / 20 is more preferable. When the molar ratio is within this range, the perfluoroelastomer (b1) has sufficient elasticity.
The total amount of the structural unit based on TFE and the structural unit based on PAVE is preferably 99 mol% or more with respect to the total of all the structural units constituting the perfluoroelastomer (b1).

  The perfluoroelastomer (b1) may further have a structural unit based on a monomer other than TFE and PAVE, if necessary. Examples of other monomers include the following monomers (m3) and monomers (m4).

The monomer (m3) is a polyfunctional perfluoromonomer having two or more polymerizable unsaturated bonds. When the monomer (m3) is radically copolymerized with TFE and PAVE, two or more polymerizable unsaturated bonds of the monomer (m3) react with each other, so that a plurality of branch points are formed in the polymer chain. It is formed.
In the monomer (m3), the number of polymerizable unsaturated bonds is preferably 2 to 6, more preferably 2 or 3, and most preferably 2.

It is preferable that any two or more polymerizable unsaturated bonds contained in the monomer (m3) have the same reactivity in radical copolymerization. Thus, when radically copolymerizing the monomer (m3) together with TFE and PAVE, each polymerizable unsaturated bond contained in the monomer (m3) reacts satisfactorily, and in the finally obtained perfluoroelastomer The residual amount of polymerizable unsaturated bonds in is reduced. The smaller the residual amount, the better the effect of the present invention.
It can be judged from the structure whether the reactivity in radical copolymerization is equivalent, for example, from the structure (another atom or group bonded to the carbon atom constituting the unsaturated bond, from the molecular end to the unsaturated bond). If the distance is the same, it can be said that they have the same reactivity.

The monomer (m3) preferably has two or more groups containing the polymerizable unsaturated bond at the end. Examples of the group containing a polymerizable unsaturated bond at the _{terminal, CF 2 = CF-O-,} CF 2 = CF- are preferred, in terms of reactivity in radical _{copolymerization,} CF 2 = CF-O- Is preferred.

As a preferable example of the monomer (m3), the formula R ^f1 ((O) _a CF═CF ₂ ) _b (wherein a represents 0 or 1, b represents an integer of 2 to 6, and R ^f1 represents , A b-valent perfluoro saturated hydrocarbon group having 1 to 25 carbon atoms which may have an etheric oxygen atom.).
In the formula, a is preferably 1.
b is preferably 2 or 3, and most preferably 2.
Examples of the perfluoro saturated hydrocarbon group for R ^f1 include groups in which b fluorine atoms have been removed from a perfluoroalkane having 1 to 25 carbon atoms, which may be linear, branched, or cyclic. A straight chain or branched chain is preferable. The number of carbon atoms is preferably 2-20, and more preferably 2-10.
The perfluoro saturated hydrocarbon group may have an etheric oxygen atom. In this case, the number of etheric oxygen atoms contained in the perfluoro saturated hydrocarbon group may be 1 or 2 or more.

As the monomer (m3), a compound in which a is 1 and b is 2 is preferable. That is, CF ₂ = CFOR ^f1 OCF = CF ₂ is preferable.
CF ₂ = CFOR ^f1 OCF = CF ₂ is CF ₂ = CFO (CF ₂ ) _c OCF = CF ₂ (where c represents an integer of 1 to 10), CF ₂ = CFO [(CF ₂ ) _d O] _f (CFX ¹ CF ₂ O) _e CF = CF ₂ (wherein, d is an integer of 1 to 10, f is an integer of 0 to 5, e is an integer of 1 to 5, X ¹ is F Or CF _3. ), And CF ₂ ═CFO (CF ₂ CFX ² O) _g [(CF ₂ ) _h O] _k (CFX ³ CF ₂ O) _i CF═CF ₂ (wherein g is 0 to 0) An integer of 5, h is an integer of 0 to 10, k is 0 or 1 (k is also 0 when h is 0), i is an integer of 1 to 5, and X ² and X ³ are each independently F or CF ₃ is shown.) At least one selected from the group consisting of:

_{CF 2} = _CFO (CF ₂₎ Examples of c OCF = CF _{2 is, CF 2 = CFO (CF 2} ) 2 OCF = CF 2, CF 2 = CFO (CF 2) 3 OCF = CF 2, CF 2 = _{CFO (CF 2) 4 OCF =} CF 2, CF 2 = CFO (CF 2) 6 OCF = CF 2, CF 2 = CFO (CF 2) 8 OCF = CF 2 , and the like.
CF ₂ = CFO [(CF ₂ ) _d O] _f (CFX ¹ CF ₂ O) _{e As} a specific example of CF = CF ₂ , CF ₂ = CFO (CF ₂ ) ₂ OCF (CF ₃ ) CF ₂ OCF = CF _{2, CF 2 = CFO (CF} 2) 2 O (CF (CF 3) CF 2 O) 2 CF = CF 2, CF 2 = CFOCF 2 O (CF 2 CF 2 O) 2 CF = CF 2, CF 2 = _{CFO (CF 2 O) 3 O} (CF (CF 3) CF 2 O) 2 CF = CF 2 , and the like.
CF ₂ = CFO (CF ₂ CFX ² O) _g [(CF ₂ ) _h O] _k (CFX ³ CF ₂ O) _{i As} a specific example of CF = CF ₂ , CF ₂ = CFOCF ₂ CF (CF ₃ ) O _{(CF 2) 2 OCF (CF} 3) CF 2 OCF = CF 2, CF 2 = CFOCF 2 CF 2 O (CF 2 O) 2 CF 2 CF 2 OCF = CF 2 and the like.
Among _{them, CF 2 = CFO (CF 2} ) c OCF = CF 2 is _{preferred, CF 2 = CFO (CF 2} ) 3 OCF = CF 2, CF 2 = CFO (CF 2) 4 OCF = CF 2 is particularly preferred .

A monomer (m3) may be used individually by 1 type, and may use 2 or more types together.
When the perfluoroelastomer (b1) has a structural unit based on the monomer (m3), the content of the monomer (m3) is the sum of the structural unit based on TFE and the structural unit based on PAVE (100 mol%) On the other hand, 0.01-1 mol% is preferable, 0.05-0.5 mol% is preferable, and 0.05-0.3 mol% is more preferable. When this content is within the above range, crosslinking reactivity is further increased. Moreover, the mechanical properties, heat resistance, chemical resistance, etc. of the resulting crosslinked product are also good.

The monomer (m4) is a monomer other than TFE, PAVE, and the monomer (m3).
As the monomer (m4), for example, a monofunctional perfluoromonomer having one polymerizable unsaturated bond (excluding TFE and PAVE), a monomer having an iodine atom and / or a bromine atom, Examples thereof include monomers having a hydrogen atom (except for monomers having an iodine atom and / or a bromine atom).

As the monofunctional perfluoromonomer, those having a group containing the polymerizable unsaturated bond at the terminal are preferable. The polymerizable unsaturated bond group containing the _{terminal, CF 2 = CF-O-,} CF 2 = CF- are preferred, in terms of reactivity in radical _{copolymerization,} CF 2 = CF-O- Is preferred.
As a preferable specific example of the monofunctional perfluoromonomer, CF ₂ = CF—R ^f2 (wherein R ^f2 represents a perfluoroalkyl group optionally having an etheric oxygen atom). The perfluoroalkene represented by these is mentioned.
Number of carbon atoms of the perfluoroalkyl group in R ^f2 is preferably 1 to 20, more preferably 1 to 10, 1 to 3 is most preferred. When the perfluoroalkyl group has an etheric oxygen atom, the number of etheric oxygen atoms contained in the perfluoroalkyl group may be 1 or 2 or more.
As the perfluoroalkyl group having an etheric oxygen atom, for example, — (CF ₂ CFXO) _y R ^f3 (wherein X represents F or CF ₃ , y represents an integer of 1 to 5, and R ^f3 represents A perfluoroalkyl group having 1 to 3 carbon atoms).

Examples of the monomer having an iodine atom and / or bromine atom include CF ₂ ═CFBr, CH ₂ ═CHCF ₂ CF ₂ Br, CF ₂ ═CF—O—CF ₂ CF ₂ —I, and CF ₂ ═CF. _{-O-CF 2 CF 2 -Br,} CF 2 = CF-O-CF 2 CF 2 CH 2 -I, CF 2 = CF-O-CF 2 CF 2 CH 2 -Br, CF 2 = CF-O-CF _{2 CF 2 (CF 3) -O} -CF 2 CF 2 CH 2 -I, CF 2 = CF-O-CF 2 CF 2 (CF 3) -O-CF 2 CF 2 CH 2 -Br and the like.

Examples of the monomer having a hydrogen atom include CF ₂ ═CF—O—CH ₂ CF ₃ , CF ₂ ═CF—O—CH ₂ CF ₂ CF ₂ CF ₃ , and CF ₂ ═CF—O—CH _2. Examples thereof include partially fluorinated monomers such as (CF ₂ CF ₂ ) ₂ H.
However, the content of the structural unit based on the monomer having a hydrogen atom is within a range where the hydrogen atom in the perfluoroelastomer (b) is 0.1% by mass or less.

  The content of hydrogen atoms in the perfluoroelastomer (b) is 0.1% by mass or less, preferably 0.07% by mass or less, and 0.05% by mass with respect to the total mass of the perfluoroelastomer (b). The following is more preferable. When the content of hydrogen atoms exceeds the upper limit, the performance of the perfluoroelastomer such as heat resistance and chemical resistance is lowered.

When the perfluoroelastomer (b) has a hydrogen atom, the hydrogen atom in the perfluoroelastomer (b) may be at the end of the polymer chain, at the side group, or in both of them. Also good.
A perfluoroelastomer having a hydrogen atom at the end of the polymer chain can be obtained, for example, by using a chain transfer agent containing a hydrogen atom when copolymerizing monomers such as TFE and PAVE. A perfluoroelastomer having a hydrogen atom in a side group of the polymer chain can be obtained, for example, by copolymerizing the aforementioned monomer having a hydrogen atom.
Examples of the chain transfer agent containing a hydrogen atom include chain or cyclic saturated hydrocarbons such as methane, ethane, propane, butane, pentane, hexane, and cyclohexane, alcohols such as methanol, ethanol, and propanol, and tert-dodecyl mercaptan. And mercaptans such as n-dodecyl mercaptan and n-octadecyl mercaptan.

The perfluoroelastomer (b) preferably has an iodine atom and / or a bromine atom, and particularly preferably has an iodine atom.
The content of iodine atoms and / or bromine atoms in the perfluoroelastomer (b) is not particularly limited, but is preferably 0.1 to 1.5% by mass with respect to the total mass of the perfluoroelastomer (b). 0.1 to 1.0% by mass is more preferable, and 0.2 to 1.0% by mass is particularly preferable. Within this range, an elastomer composition that provides a crosslinked product having excellent rubber properties and compression set properties can be obtained.

When the perfluoroelastomer (b) has an iodine atom and / or a bromine atom, the iodine atom and / or bromine atom in the perfluoroelastomer (b) may be at the terminal of the polymer chain and may be present in the side group. Or both of them. From the viewpoint of crosslinking reactivity, it is preferably at least at the end of the polymer chain.
A perfluoroelastomer having an iodine atom and / or a bromine atom at the end of a polymer chain may be used, for example, when a chain transfer agent containing an iodine atom and / or a bromine atom is copolymerized with a monomer such as TFE or PAVE. It is obtained by using. The perfluoroelastomer having a hydrogen atom in the side group of the polymer chain can be obtained, for example, by copolymerizing the aforementioned monomer having an iodine atom and / or a bromine atom.
Examples of the chain transfer agent containing an iodine atom and / or a bromine atom include, for example, an iodo compound represented by the formula RI ₂ (wherein R is an alkylene group or a perfluoroalkylene group having 3 or more carbon atoms). Is mentioned.

The perfluoroelastomer (b) is preferably an elastic copolymer having a structural unit based on TFE and a structural unit based on CF ₂ ═CF—O—R ^f , and any combination of the following (Y1) to (Y2) A copolymer consisting of the following structural units is more preferred.
(Y1): A combination of a structural unit based on TFE and a structural unit based on CF ₂ = CF—O—R ^f .
(Y2): The combination of the structural units based on _TFE, and structural units based on ^{CF 2 = CF-O-R} f, and structural units based on ^{CF 2 = CFOR f1 OCF = CF} 2.

The copolymer composition in (Y1) to (Y2) is preferably the following molar ratio.
(Y1): Structural unit based on TFE / CF ₂ = Structural unit based on CF—O—R ^f = 40/60 to 80/20 (molar ratio).
(Y2): Structural unit based on TFE / CF ₂ = Structural unit based on CF—O—R ^f / CF ₂ = CFOR ^f1 Structural unit based on OCF = CF ₂ = 40-80 / 20-60 / 20-60 ( Molar ratio).

  The Mooney viscosity of the perfluoroelastomer (b) is preferably 1 to 100, more preferably 5 to 90, still more preferably 5 to 80, and particularly preferably 5 or more and less than 70. When the Mooney viscosity is within this range, the processability, the mechanical properties of the crosslinked product, and the like are good.

  The storage shear modulus G ′ of the perfluoroelastomer (b) is preferably 50 to 700 kPa, and more preferably 100 to 650 kPa. When the storage shear modulus G ′ is within this range, the processability, the mechanical properties of the crosslinked product, and the like are good.

  The Tg of the perfluoroelastomer (b) is preferably 15 ° C. or less, more preferably −50 to 10 ° C., further preferably −50 to 0 ° C., and particularly preferably −50 to −3 ° C. If Tg is not more than the above upper limit value, the low temperature characteristics are more excellent.

The perfluoroelastomer (b) is, for example, at least one selected from the group consisting of TFE, PAVE, and, if necessary, the monomer (m3) and the monomer (m4) in the presence of a radical polymerization initiator. Can be produced by a production method in which
The copolymerization may be performed in the presence of a chain transfer agent. As the chain transfer agent, those having an iodine atom and / or a bromine atom are preferable.
The production of perfluoroelastomer (b) by the above production method can be carried out by utilizing the methods disclosed in International Publication No. 2007/119434, International Publication No. 2010/082633 and the like.

<Other ingredients>
The elastomer composition (1) further contains other components other than the fluorinated elastic copolymer (a) and the perfluoroelastomer (b) as necessary, as long as the effects of the present invention are not impaired. May be.
Examples of the other components include other elastomers and additives other than the fluorinated elastic copolymer (a) and the perfluoroelastomer (b).

Other elastomers include, for example, a fluorine-containing elastic copolymer having a structural unit based on TFE and a structural unit based on P and having no iodine atom, a structural unit based on HFP, and a structural unit based on VdF. Copolymers (for example, a fluorinated elastic copolymer (c) described later).
As the additive, known additives can be used, and examples thereof include organic peroxides, crosslinking aids, metal oxides, color pigments, fillers, reinforcing agents and the like.

The organic peroxide is used to make the elastomer composition (1) into a crosslinked product.
Examples of the organic peroxide include dialkyl peroxides, 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxyperoxide. Benzoyl peroxide, tert-butylperoxybenzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxymaleic acid, tert-butylperoxysopropyl carbonate, and the like. . Of these, dialkyl peroxides are preferred.
Examples of the dialkyl peroxides include ditert-butyl peroxide, tert-butylcumyl peroxide, dicumyl peroxide, α, α-bis (tert-butylperoxy) -p-diisopropylbenzene, 2,5- Examples include dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) -3-hexyne and the like.

The crosslinking aid is used to further increase the crosslinking reactivity when the elastomer composition (1) is crosslinked with an organic peroxide to form a crosslinked product.
Examples of the crosslinking aid include triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, 1,3,5-triacryloylhexahydro-1,3,5-triazine, triallyl trimellitate, m- Phenylenediamine bismaleimide, p-quinone dioxime, p, p'-dibenzoylquinone dioxime, dipropargyl terephthalate, diallyl phthalate, N, N ', N ", N'''-tetraallyl terephthalamide, vinyl And group-containing siloxane oligomers (polymethylvinylsiloxane, polymethylphenylvinylsiloxane, etc.). Of these, triallyl cyanurate, triallyl isocyanurate, and trimethallyl isocyanurate are preferable, and triallyl isocyanurate is more preferable.

The metal oxide is used for promoting the crosslinking reaction.
The metal oxide is preferably a divalent metal oxide. Examples of the divalent metal oxide include magnesium oxide, calcium oxide, zinc oxide, lead oxide and the like.

  Examples of fillers or reinforcing agents include carbon black, titanium oxide, silicon dioxide, clay, talc, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, ethylene tetrafluoride / ethylene copolymer Examples thereof include a copolymer and a tetrafluoroethylene / vinylidene fluoride copolymer.

<Combination ratio>
In the elastomer composition (1), the mass ratio [(a) / (b)] between the fluorinated elastic copolymer (a) and the perfluoroelastomer (b) is 1/99 to 99/1. 10/90 to 90/10 are preferable, and 70/30 to 30/70 are more preferable. When the blending ratio of the fluorinated elastic copolymer (a) is at least the lower limit of the above range, the crosslinking reactivity, the compression set characteristics of the crosslinked product and the alkali resistance are excellent. If the compounding ratio of the perfluoroelastomer (b) is at least the lower limit of the above range, the heat resistance of the crosslinked product is excellent.

  The content of the other elastomer is preferably 0 to 50 parts by mass with respect to 100 parts by mass in total of the fluorinated elastic copolymer (a) and the perfluoroelastomer (b).

  When the elastomer composition (1) contains an organic peroxide, the content of the organic peroxide is 100 parts by mass in total of the fluorinated elastic copolymer (a) and the perfluoroelastomer (b). On the other hand, 0.3-10 mass parts is preferable, 0.3-5 mass parts is more preferable, and 0.5-3 mass parts is further more preferable. When the content of the organic peroxide is in the above range, the crosslinking rate is appropriate, and the obtained crosslinked product has more excellent tensile strength and compression set at high temperatures.

  When the elastomer composition (1) contains a crosslinking aid, the content of the crosslinking aid is based on a total of 100 parts by mass of the fluorinated elastic copolymer (a) and the perfluoroelastomer (b). 0.1-20 mass parts is preferable, and 1-10 mass parts is more preferable. When the content of the crosslinking aid is in the above range, the crosslinking rate is appropriate, and the obtained crosslinked product has more excellent tensile strength and compression set at high temperatures.

  When the elastomer composition (1) contains a metal oxide, the content of the metal oxide is 100 parts by mass in total of the fluorinated elastic copolymer (a) and the perfluoroelastomer (b). 0.1-10 mass parts is preferable, and 0.5-5 mass parts is more preferable.

<Manufacturing method>
The elastomer composition (1) can be produced by mixing the fluorinated elastic copolymer (a), the perfluoroelastomer (b), and other components as necessary.
Mixing of each component can be performed using well-known kneading apparatuses, such as a roll, a kneader, a Banbury mixer, and an extruder.

<Application>
The elastomer composition (1) can be crosslinked to form a crosslinked product.
Examples of the crosslinking method of the elastomer composition (1) include a method of heating the elastomer composition (1) and a method of irradiating the elastomer composition (1) with radiation. Specific examples of the method of crosslinking by heating include hot press crosslinking, steam crosslinking, hot air crosslinking and the like. Examples of radiation to be irradiated include electron beams and ultraviolet rays. 0.1-30 Mrad is preferable and, as for the irradiation amount in electron beam irradiation, 1-20 Mrad is more preferable. The cross-linking method may be appropriately selected in consideration of the shape and use of the cross-linked product.
When the elastomer composition (1) is crosslinked by heating, the elastomer composition (1) preferably contains an organic peroxide. In the case of crosslinking by radiation irradiation, the elastomer composition (1) may be a composition not containing an organic peroxide.

As an example of a method for producing a crosslinked product, there may be mentioned a method in which a molded product is obtained by molding and primary crosslinking of the elastomer composition (1), and then a crosslinked product is obtained by performing secondary crosslinking. Secondary crosslinking is not essential, but by performing secondary crosslinking, the mechanical properties, compression set, and other properties of the crosslinked product can be stabilized or improved.
Examples of the molding method of the elastomer composition (1) include a compression molding method, an injection molding method, an extrusion molding method, a calender molding method, or a method in which it is dissolved in a solvent, dipped, coated and molded.
Examples of the primary crosslinking method for the elastomer composition (1) include the crosslinking methods mentioned above. When primary crosslinking is performed by heating, the heating condition is preferably in the range of several seconds to 24 hours at 100 to 400 ° C.
The elastomer composition (1) may be molded and then primary crosslinked, or the elastomer composition (1) may be crosslinked and molded. The elastomer composition (1) can be crosslinked at the same time as it is molded by the method of hot pressing the elastomer composition (1).
Examples of the secondary crosslinking method include the crosslinking methods mentioned above. When secondary crosslinking is performed by heating, the heating condition is preferably about 100 to 300 ° C. for about 30 minutes to 48 hours.

<Effect>
The elastomer composition (1) has an iodine atom, a fluorinated elastic copolymer (a) having a structural unit based on TFE and a structural unit based on P, and a hydrogen atom content of 0.1% by mass or less. Perfluoroelastomer (b), and the mass ratio [(a) / (b)] of the fluorinated elastic copolymer (a) to the perfluoroelastomer (b) is 1/99 to 99 / Since it is 1, it is excellent in crosslinking reactivity. Further, the cross-linked product is excellent in heat resistance, compression set characteristics and alkali resistance.
Further, the perfluoroelastomer (b) is relatively expensive although it is excellent in performance. By using the fluorinated elastic copolymer (a) in combination, the cost can be reduced while maintaining the excellent properties of the perfluoroelastomer (b).

<< Elastomer Composition of Second Aspect >>
The elastomer composition of the second aspect of the present invention (hereinafter also referred to as “elastomer composition (2)”) comprises the following fluorinated elastic copolymer (a) and fluorinated elastic copolymer (c). contains.

<Fluorine-containing elastic copolymer (a)>
The fluorinated elastic copolymer (a) is the same as the fluorinated elastic copolymer (a) in the elastomer composition (1), and the preferred embodiment is also the same.

<Fluorine-containing elastic copolymer (c)>
The fluorinated elastic copolymer (c) is a fluorinated elastic copolymer (excluding the fluorinated elastic copolymer (a)) having a structural unit based on HFP and a structural unit based on VdF.
The fluorinated elastic copolymer (c) typically does not have a structural unit based on P, and is distinguished from the fluorinated elastic copolymer (a) in this respect.

In the fluorinated elastic copolymer (c), the molar ratio of the structural unit based on HFP and the structural unit based on VdF [the structural unit based on HFP / the structural unit based on VdF] is preferably 15/85 to 50/50. 20/80 to 60/40 are more preferable, and 25/75 to 65/35 are more preferable. When it is in this range, the mechanical properties of the crosslinked product are more excellent.
The total amount of the structural unit based on HFP and the structural unit based on VdF is preferably 99 mol% or more with respect to the total of all the structural units constituting the fluorinated elastic copolymer (c).

The fluorinated elastic copolymer (c) may further have a structural unit based on a monomer (m5) other than HFP and VdF, if necessary.
As the monomer (m5), any monomer that can be copolymerized with HFP and VdF may be used. For example, TFE, CTFE, PAVE, vinyl fluoride, pentafluoropropylene, perfluorocyclobutene, and (perfluoroalkyl) ethylenes. (e.g. _{CH 2 = CHCF 3, CH 2} = CHCF 2 CF 3, CH 2 = CHCF 2 CF 2 CF 3, CH 2 = CHCF 2 CF 2 CF 2 CF 3, CH 2 = CHCF 2 CF 2 CF 2 CF 2 CF ₃ ), etc .; α-olefins such as E, isobutylene and pentene; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether and butyl vinyl ether; vinyl acetate, vinyl propionate, vinyl butyrate, Such as vinyl caproate, vinyl caprylate Non-fluorine-containing monomers Niruesuteru and the like; and the like. These monomers may be used individually by 1 type, and may use 2 or more types together. As PAVE, the thing similar to what was mentioned by the said monomer (m2) is mentioned, A preferable aspect is also the same.
As the monomer (m5), TFE is preferable among the above.

A monomer (m5) may be used individually by 1 type, and may use 2 or more types together.
When the fluorinated elastic copolymer (c) has a structural unit based on the monomer (m5), the content of the structural unit based on the monomer (m5) constitutes the fluorinated elastic copolymer (c). 0.01-10 mol% is preferable with respect to the total (100 mol%) of all the structural units to perform, 0.01-5 mol% is more preferable, 0.01-1 mol% is especially preferable.

As the fluorinated elastic copolymer (c), a copolymer composed of structural units of any combination of the following (Z1) to (Z2) is preferable.
(Z1): A combination of a structural unit based on HFP and a structural unit based on VdF.
(Z2): A combination of a structural unit based on HFP, a structural unit based on VdF, and a structural unit based on TFE.

The copolymer composition in (Z1) to (Z2) is preferably the following molar ratio.
(Z1): Structural unit based on HFP / Structural unit based on VdF = 15 / 85-50 / 50 (molar ratio).
(Z2): Structural unit based on HFP / Structural unit based on VdF / Structural unit based on TFE = 20-30 / 50-70 / 5-15 (molar ratio).

  The Mooney viscosity of the fluorinated elastic copolymer (c) is preferably from 10 to 200, more preferably from 20 to 180, and even more preferably from 30 to 170. When the Mooney viscosity is within this range, the processability, the mechanical properties of the crosslinked product, and the like are good.

  The storage shear modulus G ′ of the fluorinated elastic copolymer (c) is preferably from 100 to 600 kPa, more preferably from 100 to 500 kPa, and even more preferably from 100 to 400 kPa. When the storage shear modulus G ′ is within this range, the processability, the mechanical properties of the crosslinked product, and the like are good.

  Tg of the fluorinated elastic copolymer (c) is preferably 15 ° C. or less, more preferably −50 to 10 ° C., further preferably −50 to 0 ° C., and particularly preferably −50 to −3 ° C. If Tg is not more than the above upper limit value, the low temperature characteristics are more excellent.

As the fluorinated elastic copolymer (c), a commercially available product may be used, or a product produced by a known production method may be used.
The fluorinated elastic copolymer (c) can be produced, for example, by a production method in which HFP, VdF, and, if necessary, a monomer (m5) are copolymerized in the presence of a radical polymerization initiator. The copolymerization may be performed in the presence of a chain transfer agent.

<Other ingredients>
If necessary, the elastomer composition (2) may contain other components other than the fluorinated elastic copolymer (a) and the fluorinated elastic copolymer (c) as long as the effects of the present invention are not impaired. Furthermore, you may contain.
Examples of other components include other elastomers and additives other than the fluorinated elastic copolymer (a) and the fluorinated elastic copolymer (c).

Examples of the other elastomer include a fluorinated elastic copolymer having a structural unit based on TFE and a structural unit based on P, and having no iodine atom, and the perfluoroelastomer (b) described above.
As the additive, known additives can be used, and examples thereof include organic peroxides, crosslinking aids, metal oxides, color pigments, fillers, reinforcing agents and the like. Specific examples of these additives are the same as those mentioned for the elastomer composition (1), and preferred embodiments are also the same.

<Combination ratio>
In the elastomer composition (2), the mass ratio [(a) / (c)] of the fluorinated elastic copolymer (a) to the fluorinated elastic copolymer (c) is 1/99 to 99 / 1, 10/90 to 90/10 are preferable, and 70/30 to 30/70 are more preferable. When the blending ratio of the fluorinated elastic copolymer (a) is at least the lower limit of the above range, the alkali resistance of the crosslinked product is excellent. When the blending ratio of the fluorinated elastic copolymer (c) is at least the lower limit of the above range, the low-temperature properties of the crosslinked product are excellent.

  The content of the other elastomer is preferably 0 to 50 parts by mass with respect to 100 parts by mass in total of the fluorinated elastic copolymer (a) and the fluorinated elastic copolymer (c).

  When the elastomer composition (2) contains an organic peroxide, the content of the organic peroxide is a total of 100 of the fluorinated elastic copolymer (a) and the fluorinated elastic copolymer (c). 0.3-10 mass parts is preferable with respect to mass parts, 0.3-5 mass parts is more preferable, and 0.5-3 mass parts is still more preferable. When the content of the organic peroxide is in the above range, the crosslinking rate is appropriate, and the obtained crosslinked product has more excellent tensile strength and compression set at high temperatures.

  When the elastomer composition (2) contains a crosslinking aid, the content of the crosslinking aid is 100 parts by mass in total of the fluorinated elastic copolymer (a) and the fluorinated elastic copolymer (c). Is preferably 0.1 to 20 parts by mass, and more preferably 1 to 10 parts by mass. When the content of the crosslinking aid is in the above range, the crosslinking rate is appropriate, and the obtained crosslinked product has more excellent tensile strength and compression set at high temperatures.

  When the elastomer composition (2) contains a metal oxide, the content of the metal oxide is 100 parts by mass in total of the fluorinated elastic copolymer (a) and the fluorinated elastic copolymer (c). Is preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass.

<Manufacturing method>
The elastomer composition (2) can be produced by mixing the fluorinated elastic copolymer (a), the fluorinated elastic copolymer (c), and other components as necessary.
Mixing of each component can be performed using well-known kneading apparatuses, such as a roll, a kneader, a Banbury mixer, and an extruder.

<Application>
The elastomer composition (2) can be crosslinked to form a crosslinked product.
Examples of the crosslinking method of the elastomer composition (2) include the same methods as the crosslinking method of the elastomer composition (1), and preferred embodiments are also the same.

<Effect>
The elastomer composition (2) has an iodine atom, a fluorinated elastic copolymer (a) having a structural unit based on TFE and a structural unit based on P, a structural unit based on HFP, and a structural unit based on VdF. A fluorinated elastic copolymer (c) having a mass ratio [(a) / (c)] of the fluorinated elastic copolymer (a) and the fluorinated elastic copolymer (c). Since it is 1 / 99-99 / 1, the low-temperature characteristic and alkali resistance of the crosslinked product are excellent.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not construed as being limited thereto. Each physical property of the fluorinated elastic copolymer was measured by the following method.

-Copolymer composition of fluorinated elastic copolymer:
The copolymer composition (molar ratio of each structural unit) of the fluorinated elastic copolymer was determined by ¹⁹ F-nuclear magnetic resonance (NMR) analysis, fluorine content analysis, and infrared absorption spectrum analysis.

・ Iodine content of fluorinated elastic copolymer:
The iodine content in the fluorinated elastic copolymer was quantified by an apparatus combining a pretreatment device AQF-100 for an automatic sample combustion apparatus ion chromatograph manufactured by Dia Instruments and an ion chromatograph.

-Storage shear modulus G 'of fluorinated elastic copolymer:
Using RPA2000 manufactured by Alpha Technologies in accordance with ASTM D5289 and D6204, a value measured at a temperature of 100 ° C., an amplitude of 0.5 degree, and a frequency of 50 times / minute was defined as a storage shear modulus G ′.

-Mooney viscosity of fluorinated elastic copolymer:
The Mooney viscosity of the fluorinated elastic copolymer is 100 ° C. with a preheating time of 1 minute using an L-shaped rotor having a diameter of 38.1 mm and a thickness of 5.54 mm in accordance with JIS K6300-1: 2013. The time was set at 4 minutes and measured.

-Glass transition temperature (Tg) of fluorinated elastic copolymer:
Using a differential scanning calorimeter (DSC220 manufactured by Seiko Instruments Inc.), 10 ± 0.1 mg of fluorinated elastic copolymer was heated from −50 ° C. to 150 ° C. at 10 ° C./min. The center temperature of the endothermic peak change when cooled to -50 ° C in minutes was defined as the glass transition temperature.

The fluorinated elastic copolymer used in each example described below is shown below.
Abbreviations of monomers in each fluorinated elastic copolymer are as follows.
TFE: tetrafluoroethylene.
P: Propylene.
_{C4DVE: CF 2 = CFO (CF} 2) 4 OCF = CF 2.
_{C3DVE: CF 2 = CFO (CF} 2) 3 OCF = CF 2.
HFP: hexafluoropropylene.
VdF: Vinylidene fluoride.

(Fluorine-containing elastic copolymer (a))
-Fluorine-containing elastic copolymer A:
A TFE / P copolymer having an iodine atom at the end of the polymer chain. TFE / P = 56/44 (molar ratio), iodine content 0.3 mass%, Mooney viscosity 80, Tg-3 ° C. A synthetic product synthesized according to Example 1 of International Publication No. 2009/119202.
-Fluorine-containing elastic copolymer B:
A TFE / P / C4DVE copolymer having an iodine atom at the end of the polymer chain. TFE / P / C4DVE = 56 / 43.8 / 0.2 (molar ratio), iodine content 0.5% by mass, Mooney viscosity 95, Tg-3 ° C. A synthetic product synthesized in Production Example 1 below.
-Fluorine-containing elastic copolymer C:
A TFE / P / C3DVE copolymer having an iodine atom at the end of the polymer chain. TFE / P / C3DVE = 56 / 43.8 / 0.2 (molar ratio), iodine content 0.5% by mass, Mooney viscosity 95, Tg-3 ° C. A synthetic product synthesized in Production Example 2 below.

(Fluorine-containing elastic copolymer (c))
-Fluorine-containing elastic copolymer D:
HFP / VdF copolymer. Mooney viscosity 66, Tg-20.0 ° C., fluorine content 66 mass%.
-Fluorine-containing elastic copolymer E:
HFP / VdF / TFE copolymer. Mooney viscosity 80, Tg-14.0 ° C., fluorine content 69 mass%.

(Perfluoroelastomer (b))
-Fluorine-containing elastic copolymer F:
A TFE / PMVE copolymer having an iodine atom at the end of the polymer chain. TFE / PMVE = 69.0 / 31.0 (molar ratio), iodine content 0.2 mass%, storage shear modulus G′540 kPa. A synthetic product synthesized in accordance with Comparative Example 1 of WO2010 / 082633.
-Fluorine-containing elastic copolymer G:
A TFE / PMVE / C4DVE copolymer having an iodine atom at the end of the polymer chain. TFE / PMVE / C4DVE = 76.0 / 24.0 / 0.1 (molar ratio), iodine content 0.3 mass%, storage shear modulus G′614 kPa. A synthetic product synthesized according to Example 1 of WO2010 / 082633.

(Other)
-Fluorine-containing elastic copolymer H:
A TFE / P copolymer having no iodine atom. TFE / P = 56/44 (molar ratio). A synthetic product synthesized in Production Example 3 below.

(Production Example 1)
After degassing the inside of a 3200 mL stainless steel pressure-resistant reactor equipped with an anchor blade for stirring, 1500 g of ion-exchanged water, 59 g of disodium hydrogen phosphate 12 hydrate, 0.7 g of sodium oxide, 197 g of tert-butanol, 9 g of sodium lauryl sulfate, 9 g of 1,4-diiodoperfluorobutane, 11.2 g of C4DVE and 6 g of ammonium persulfate were added. Furthermore, an aqueous solution in which 0.4 g of ethylenediaminetetraacetic acid disodium salt dihydrate (hereinafter referred to as EDTA) and 0.3 g of ferrous sulfate heptahydrate were dissolved in 100 g of ion-exchanged water, Added to the reactor. At this time, the pH of the aqueous medium in the reactor was 9.5.
Next, at 25 ° C., a monomer mixed gas of TFE / P = 88/12 (molar ratio) was injected so that the internal pressure of the reactor was 2.50 MPaG (G indicates a gauge pressure). . An anchor blade was rotated at 300 rpm, and then a 2.5% by mass aqueous solution of sodium hydroxymethanesulfinate dihydrate (hereinafter referred to as Rongalite) adjusted to pH 10.0 with sodium hydroxide (hereinafter referred to as Rongalite). 2.5% by weight aqueous solution) was added to the reactor to initiate the polymerization reaction. Thereafter, Rongalite 2.5 mass% aqueous solution was continuously added to the reactor using a high-pressure pump.
When the total amount of the TFE / P monomer mixture gas injected reaches 1000 g, the addition of Rongalite 2.5 mass% aqueous solution is stopped, the internal temperature of the reactor is cooled to 10 ° C., and the polymerization reaction is performed. The reaction was stopped and latex of fluorinated elastic copolymer B was obtained. The amount of Rongalite 2.5 mass% aqueous solution added was 68 g. The polymerization time was 6 hours.
A 5% by mass aqueous solution of calcium chloride was added to the latex, and the latex of the fluorinated elastic copolymer B was agglomerated to precipitate the fluorinated elastic copolymer B. The fluorinated elastic copolymer B was recovered by filtration and washed with ion-exchanged water to obtain 980 g of a white fluorinated elastic copolymer B.

(Production Example 2)
A fluorinated elastic copolymer C was obtained in the same manner as in Example 1 except that C4DVE was changed to 9.8 g of C3DVE.

(Production Example 3)
According to the comparative example 2 of international publication 2009/119202, the TFE / P copolymer (TFE / P = 56/44 (molar ratio)) which does not have an iodine atom was obtained. This TFE / P copolymer was heat-treated using an oven at 300 ° C. for 15 hours to obtain a fluorinated elastic copolymer H.
About the obtained fluorinated elastic copolymer H, the infrared absorption spectrum was measured in accordance with the measuring method described in Japanese Patent No. 5109150. The infrared absorption spectrum had an absorption peak at 1640-1700 cm ⁻¹ . This absorption peak is attributed to the carbon-carbon unsaturated bond. This absorption peak was not observed before the heat treatment, and it was confirmed that a carbon-carbon unsaturated bond was formed by the heat treatment. The carbon-carbon unsaturated bond is supposed to enhance the crosslinking reactivity like the iodine atom.

Example 1
50 parts by mass of fluorinated elastic copolymer A, 50 parts by mass of fluorinated elastic copolymer D, 30 parts by mass of carbon black, 5 parts by mass of triallyl isocyanurate, and 1,3-bis (tert-butyl One part by mass of peroxyisopropyl) benzene (trade name “Perkadox 14” manufactured by Kayaku Akzo Co., Ltd.) was kneaded with two rolls for 10 minutes at room temperature to obtain an elastomer composition.
The obtained elastomer composition was evaluated for alkali resistance and low temperature characteristics by the following procedure. The results are shown in Table 1.

[Alkali resistance]
The elastomer composition was press-molded to produce a sample for evaluation (a cross-linked product having a size of 13 mm × 13 mm and a thickness of 1 mm).
The sample was immersed in a 20% NaOH aqueous solution in a sample bottle, held at 100 ° C. for 180 hours, taken out, and subjected to volume measurement and visual observation. From the volume measurement result, the volume change rate before and after immersion was calculated. From these results, alkali resistance was evaluated according to the following criteria.
A: Volume change rate ≦ 5%.
○: 5% <volume change rate ≦ 40%.
X: Any change of coloring, swelling, and shrinkage was observed in the sample.

[Low temperature characteristics]
According to JIS K6261 (2006), a low temperature elastic recovery test (TR test) was performed on a test piece prepared by press molding the elastomer composition, and TR10 was obtained. TR10 indicates a temperature at which the shrinkage rate becomes 10%.
From the obtained TR10, the low temperature characteristics were evaluated according to the following criteria.
A: TR10 ≦ −10 ° C.
○: −10 ° C. <TR10 ≦ −5 ° C.
×: −5 ° C. <TR10.

(Examples 2-7, Comparative Examples 1-4)
An elastomer composition was obtained in the same manner as in Example 1 except that the type and blending amount (part by mass) of the fluorinated elastic copolymer to be blended were changed as shown in Tables 1-2.
About the obtained elastomer composition, it carried out similarly to Example 1, and evaluated alkali resistance and a low temperature characteristic. The results are shown in Tables 1-2.

As described above, the crosslinked products of the elastomer compositions of Examples 1 to 7 were excellent in alkali resistance and low temperature characteristics at high temperatures.
On the other hand, the crosslinked product of the elastomer compositions of Comparative Examples 1 and 2 using the fluorinated elastic copolymer (a) alone as an elastomer was inferior in low temperature characteristics.
The crosslinked product of the elastomer composition of Comparative Examples 3 to 4 using the fluorinated elastic copolymer (c) alone as the elastomer was inferior in alkali resistance at high temperatures.

(Examples 8-15, Comparative Examples 5-7)
An elastomer composition was obtained in the same manner as in Example 1 except that the type and blending amount (parts by mass) of the fluorinated elastic copolymer to be blended were changed as shown in Tables 3-4.
About the obtained elastomer composition, it carried out similarly to Example 1, and evaluated alkali resistance. Furthermore, crosslinking properties by the following procedure _{(M H -M L, T90)} , the physical properties (tensile strength, elongation at break, C / S), the heat resistance was evaluated. The results are shown in Tables 3-4.

[Crosslinking characteristics]
The resulting elastomeric composition, crosslinking characteristics measuring using (Alpha Technologies Inc., trade name "RPA2000"), 12 minutes at 170 ° C., crosslinking properties in amplitude three times condition _(M H _-M L, T ₉₀ ) was measured.
M _H represents the maximum torque, _{M L} represents the minimum value of the _torque, M H -M _L indicates the degree of crosslinking. M _H -M _L becomes crosslinking reactivity index of the elastomer composition, indicating that as the value of M _H -M _L is large, excellent crosslinking reactivity. The unit of torque is dN · m.
T ₉₀ is 90% crosslinking time and represents the time (minutes) required to reach 90% of the maximum torque shown during the measurement of crosslinking properties. A smaller T ₉₀ indicates faster crosslinking.

The _M H -M _L and _{T 90} were measured and evaluated according to the following criteria.
"Evaluation criteria for _MH - _ML "
A: 60 dN · m ≦ _MH − _ML .
○: 30 dN · m ≦ M _H −M _L <60 dN · m.
(Triangle | delta): _MH - _ML <30dN * m.
"Evaluation criteria of _{T 90"}
A: T ₉₀ <4 minutes.
○: 4 minutes ≦ T ₉₀ <6 minutes.
Δ: 6 minutes ≦ T ₉₀ .

[Physical properties]
The elastomer composition was thermoformed under conditions of 130 ° C. × 20 minutes to obtain a sheet-like primary cross-linked product having a thickness of 1 mm. Next, secondary crosslinking was performed under the conditions of 250 ° C. × 4 hours to obtain a crosslinked product. According to JIS K6251 (2004), the obtained cross-linked product is punched into a No. 4 dumbbell shape to obtain a test piece, and a tensile test at room temperature using a testing machine (product name: quick reader) manufactured by Ueshima Seisakusho. The tensile strength and elongation at break were measured.
Separately, the elastomer composition was subjected to a compression set test at 200 ° C. for 72 hours in accordance with JIS K6262 (1997), and the compression set rate (C / S) was measured.

The measured tensile strength, elongation and C / S were evaluated according to the following criteria.
"Evaluation criteria for tensile strength"
A: 18 MPa ≦ tensile strength.
A: 10 MPa ≦ tensile strength <18 MPa.
Δ: Tensile strength <10 MPa.
“Evaluation criteria for growth”
A: 300% ≦ elongation.
○: 150% ≦ elongation <300%.
Δ: Elongation <150%.
"C / S evaluation criteria"
A: C / S <15%.
○: 15% ≦ C / S <40%.
Δ: 40% ≦ C / S%.

[Heat-resistant]
A heat aging test was performed on the test piece prepared in the above evaluation of physical properties in accordance with JIS K6257 (2003) under the conditions of 270 ° C. × 168 hours. After the test, the physical properties (tensile strength, elongation at break, C / S) of each test piece were measured by the procedure described above.
The rate of change (%) of each physical property was determined from the measured values of tensile strength before and after thermal aging test, elongation at break, and C / S.
Rate of change = | Measured value after heat aging test−Measured value before heat aging test | / Measured value before heat aging test × 100

The change rate of each measured physical property was evaluated according to the following criteria.
"Evaluation criteria for rate of change in tensile strength"
A: Tensile strength change rate <10%.
○: 10% ≦ tensile strength change rate <30%.
Δ: 30% ≦ Tensile strength change rate.
"Evaluation criteria for rate of change in elongation"
A: Elongation change rate <150.
○: 150% ≦ elongation change <300%.
Δ: 300% ≦ Elongation change rate.
"Evaluation criteria for C / S change rate"
A: C / S change rate <60%.
A: 60% ≦ C / S change rate <80%.
Δ: 80% ≦ C / S change rate.

As described above, the elastomer compositions of Examples 8 to 15 were excellent in crosslinking reactivity. Further, the crosslinked product was excellent in heat resistance, compression set characteristics and alkali resistance at high temperature.
On the other hand, the crosslinked product of the elastomer composition of Comparative Example 5 using the fluorinated elastic copolymer (a) alone as an elastomer was inferior in low temperature characteristics.
A perfluoroelastomer (b), has structural units based on structural units and P based on TFE, the elastomer composition of Comparative Example 6 in which a combination of a no elastic fluorocopolymer iodine atom, T ₉₀ is Low and inferior in crosslinking reactivity. Moreover, compression set characteristics, tensile strength, and heat resistance of those characteristics were inferior.
The elastomer composition of Comparative Example 7 in which the perfluoroelastomer (b) and the fluorinated elastic copolymer (c) were combined was inferior in alkali resistance at high temperatures.

Claims (4)

A fluorine-containing elastic copolymer (a) having an iodine atom and a structural unit based on tetrafluoroethylene and a structural unit based on propylene, and a perfluoroelastomer having a hydrogen atom content of 0.1% by mass or less (b) ) And
An elastomer composition having a mass ratio [(a) / (b)] of 1/99 to 99/1 between the fluorinated elastic copolymer (a) and the perfluoroelastomer (b). The perfluoroelastomer (b) is, in the constituent units and ^{_{CF 2 = CF-O-R}} f ( formula based on tetrafluoroethylene, ^{R f} is a good 20 carbon atoms which may have an etheric oxygen atom The elastomer composition according to claim 1, which has a structural unit based on a perfluoroalkyl group. A fluorine-containing elastic copolymer (a) having an iodine atom and having a structural unit based on tetrafluoroethylene and a structural unit based on propylene, and a structural unit having a structural unit based on hexafluoropropylene and a structural unit based on vinylidene fluoride. Containing a fluorine elastic copolymer (c) (excluding the fluorine-containing elastic copolymer (a)),
The elastomer composition whose mass ratio [(a) / (c)] of the said fluorine-containing elastic copolymer (a) and the said fluorine-containing elastic copolymer (c) is 1/99-99/1. The fluorinated elastic copolymer (a) is a structural unit based on at least one monomer selected from the group consisting of monomers represented by the following formula (I), (II) or (III): Furthermore, the elastomer composition as described in any one of Claims 1-3 which has.
^{CR 1 R 2 = CR 3 -R} 4 -CR 5 = CR 6 R 7 ··· (I)
^{CR 8 R 9 = CR 10 -OCO} -R 11 -COO-CR 12 = CR 13 R 14 ··· (II)
CR ¹⁵ R ¹⁶ = CR ¹⁷ COOCH = CH ₂ (III)
(Wherein R ¹ , R ² , R ³ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁷ are each independently a hydrogen atom, A fluorine atom or a methyl group, wherein R ⁴ and R ¹¹ are each independently an alkylene group having 1 to 10 carbon atoms which may contain an etheric oxygen atom, or 1 to 1 carbon atom which may contain an etheric oxygen atom; 10 represents a fluoroalkylene group, and R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may contain an etheric oxygen atom.)