阅读说明：本技术 含氟弹性共聚物组合物及交联橡胶物品 (Fluorine-containing elastic copolymer composition and crosslinked rubber article ) 是由 服部裕纪子 山田武志 巨势丈裕 于 2018-07-02 设计创作，主要内容包括：提供能够得到低温特性优异、并且具有足够的硬度的交联橡胶物品的含氟弹性共聚物组合物；及低温特性优异、并且具有足够的硬度的交联橡胶物品。一种含氟弹性共聚物组合物,其包含：具有基于四氟乙烯的单元及基于CF<Sub>2</Sub>＝CFOR<Sup>f1</Sup>(其中,R<Sup>f1</Sup>为碳数1～10的全氟烷基。)的单元的含氟弹性共聚物、和具有全氟聚醚链及2个以上聚合性不饱和键的有机硅化合物。(To provide a fluorinated elastic copolymer composition which can give a crosslinked rubber article having excellent low-temperature characteristics and sufficient hardness; and a crosslinked rubber article having excellent low-temperature characteristics and sufficient hardness. A fluoroelastomer copolymer composition comprising: having units based on tetrafluoroethylene and based on CF 2 ＝CFOR f1 (wherein, R f1 Is a C1-10 perfluoroalkyl group. ) A fluorine-containing elastic copolymer having a perfluoropolyether chain and 2 or more polymerizable unsaturated bonds.)

1. A fluoroelastomer copolymer composition comprising:

a fluorine-containing elastic copolymer having units based on tetrafluoroethylene and units based on a compound represented by the following formula (1); and

an organosilicon compound having a perfluoropolyether chain and 2 or more polymerizable unsaturated bonds,

CF₂＝CFOR^f1(1)

in the formula (1), R^f1Is a C1-10 perfluoroalkyl group.

2. The fluorine-containing elastic copolymer composition according to claim 1, wherein the proportion of the organosilicon compound is 10 to 40% by mass in 100% by mass of the total of the fluorine-containing elastic copolymer and the organosilicon compound.

3. The fluoroelastomer copolymer composition according to claim 1 or 2, wherein said organosilicon compound is a perfluoropolyether chain having a valence of 2 at both ends by means of a linking groupAnd has a vinylsilyl group (CH)₂CHSi).

4. The fluorine-containing elastic copolymer composition according to any one of claims 1 to 3, wherein the organosilicon compound is a compound represented by the following formula (7),

in the formula (7), R¹Is a hydrocarbyl radical having a valence of 1, R²Is a hydrogen atom or a 1-valent hydrocarbon group, R^f7Is a 2-valent perfluoropolyether chain.

5. The fluoroelastomer copolymer composition according to any one of claims 1 to 4, further comprising a crosslinking agent.

6. The fluorine-containing elastic copolymer composition according to claim 5, wherein the crosslinking agent is contained in an amount of 0.3 to 10 parts by mass based on 100 parts by mass of the fluorine-containing elastic copolymer.

7. The fluoroelastomer copolymer composition according to claim 5 or 6, wherein the crosslinking agent is an organic peroxide.

8. The fluoroelastomer copolymer composition according to any one of claims 1 to 7, further comprising a crosslinking assistant.

9. The fluoroelastomer copolymer composition according to any one of claims 1 to 8, wherein a molar ratio of the tetrafluoroethylene-based unit to the unit based on the compound represented by formula (1) contained in the fluoroelastomer copolymer is 35/65 to 90/10.

10. The fluoroelastomer copolymer composition according to any one of claims 1 to 9, wherein the fluoroelastomer copolymer further has units based on a compound represented by the following formula (2),

CF₂＝CF(OCF₂CF₂)_n-(OCF₂)_m-OR^f2(2)

in the formula (2), R^f2Is perfluoroalkyl group with 1-4 carbon atoms, n is an integer of 0-3, m is an integer of 0-4, and n + m is an integer of 1-7.

11. The fluoroelastomer copolymer composition according to any one of claims 1 to 10, wherein the fluoroelastomer copolymer further comprises units based on a fluoromonomer having 2 or more polymerizable unsaturated bonds.

12. The fluoroelastomer copolymer composition according to any one of claims 1 to 11, wherein, with respect to the total of all units of said fluoroelastomer copolymer,

the proportion of the tetrafluoroethylene-based unit is 35 to 75 mol%,

the proportion of the unit based on the compound represented by the formula (1) is 3 to 57 mol%,

the proportion of the unit based on the compound represented by the formula (2) is 0 to 57 mol%,

the proportion of the units based on the fluorine-containing monomer having 2 or more polymerizable unsaturated bonds is 0 to 1 mol%.

13. The fluoroelastomer copolymer composition according to any one of claims 1 to 12, wherein said fluoroelastomer copolymer further comprises iodine atoms.

14. The fluorinated elastic copolymer composition according to claim 13, wherein the iodine is contained in an amount of 0.01 to 1.5% by mass based on 100% by mass of the fluorinated elastic copolymer.

15. A crosslinked rubber article obtained by crosslinking the fluorinated elastic copolymer composition according to any one of claims 1 to 14.

Technical Field

The present invention relates to a fluorine-containing elastic copolymer composition and a crosslinked rubber article.

Background

Crosslinked rubber articles obtained by crosslinking a fluorinated elastic copolymer are excellent in heat resistance, chemical resistance, oil resistance, weather resistance and the like, and therefore are used in applications under severe environments where general-purpose rubbers cannot be used.

As a fluorinated elastic copolymer composition capable of obtaining a crosslinked rubber article excellent in rubber physical properties at low temperatures (hereinafter, also referred to as low-temperature characteristics), the following are proposed in patent document 1.

A fluoroelastomer copolymer composition comprising: a fluorine-containing elastic copolymer, a fluorine-containing ether compound having a perfluoropolyether chain and 3 or more polymerizable unsaturated bonds.

Disclosure of Invention

Problems to be solved by the invention

In a low-temperature elastic recovery test (TR test), which is a test in which a crosslinked rubber article obtained by crosslinking the fluorinated elastic copolymer composition described in patent document 1 has a low temperature at which the shrinkage rate reaches 10% (hereinafter, also referred to as TR 10.), and has good low-temperature characteristics: the temperature at which the test piece frozen at a low temperature (-70 to-73 ℃) in an extended state regains elasticity with an increase in temperature and reaches a constant shrinkage rate was determined.

However, the crosslinked rubber article obtained by crosslinking the fluorinated elastic copolymer composition described in patent document 1 has insufficient hardness, and has a problem as a sealing material for use in a high-pressure part.

The present invention provides: a fluorinated elastic copolymer composition which can give a crosslinked rubber article having excellent low-temperature characteristics and sufficient hardness; and a crosslinked rubber article having excellent low-temperature characteristics and sufficient hardness.

Means for solving the problems

The present invention has the following aspects.

<1> a fluorine-containing elastic copolymer composition comprising:

a fluorine-containing elastic copolymer having units based on tetrafluoroethylene and units based on a compound represented by the following formula (1); and

an organosilicon compound having a perfluoropolyether chain and 2 or more polymerizable unsaturated bonds.

CF₂＝CFOR^f1(1)

Wherein R is^f1Is a C1-10 perfluoroalkyl group.

<2> the fluorinated elastic copolymer composition according to <1>, wherein the proportion of the organosilicon compound is 10 to 40% by mass in the total (100% by mass) of the fluorinated elastic copolymer and the organosilicon compound.

<3>According to the foregoing<1>Or<2>The fluorine-containing elastic copolymer composition wherein the organosilicon compound has a vinylsilyl group (CH) at both ends of a 2-valent perfluoropolyether chain via a linking group₂CHSi).

<4> the fluorine-containing elastic copolymer composition according to any one of <1> to <3>, wherein the organosilicon compound is a compound represented by the following formula (7).

(wherein, R¹Is a hydrocarbyl radical having a valence of 1, R²Is a hydrogen atom or a 1-valent hydrocarbon group, R^f7Is a 2-valent perfluoropolyether chain. )

<5> the fluorine-containing elastic copolymer composition according to any one of <1> to <4>, which further comprises a crosslinking agent.

<6> the fluorinated elastic copolymer composition according to <5>, wherein the crosslinking agent is contained in an amount of 0.3 to 10 parts by mass based on 100 parts by mass of the fluorinated elastic copolymer.

<7> the fluorine-containing elastic copolymer composition according to <5> or <6>, wherein the crosslinking agent is an organic peroxide.

<8> the fluorine-containing elastic copolymer composition according to any one of <1> to <7>, which further comprises a crosslinking assistant.

<9> the fluorine-containing elastic copolymer composition according to any one of <1> to <8>, wherein the molar ratio of the tetrafluoroethylene-based unit and the unit based on the compound represented by the formula (1) contained in the fluorine-containing elastic copolymer is 35/65 to 90/10.

<10> the fluorine-containing elastic copolymer composition according to any one of <1> to <9>, wherein the fluorine-containing elastic copolymer further has a unit based on a compound represented by the following formula (2).

CF₂＝CF(OCF₂CF₂)_n-(OCF₂)_m-OR^f2(2)

Wherein R is^f2Is perfluoroalkyl group with 1-4 carbon atoms, n is an integer of 0-3, m is an integer of 0-4, and n + m is an integer of 1-7.

<11> the fluorinated elastic copolymer composition according to any one of <1> to <10>, wherein the fluorinated elastic copolymer further has a unit based on a fluorinated monomer having 2 or more polymerizable unsaturated bonds.

<12> the fluorinated elastic copolymer composition according to any one of <1> to <11>, wherein the proportion of the units based on tetrafluoroethylene is 35 to 75 mol%, the proportion of the units based on the compound represented by the formula (1) is 3 to 57 mol%, the proportion of the units based on the compound represented by the formula (2) is 0 to 57 mol%, and the proportion of the units based on a fluorinated monomer having 2 or more polymerizable unsaturated bonds is 0 to 1 mol% based on the total amount of all units of the fluorinated elastic copolymer.

<13> the fluorine-containing elastic copolymer composition according to any one of <1> to <12>, wherein the fluorine-containing elastic copolymer further contains an iodine atom.

<14> the fluorine-containing elastic copolymer composition according to <13>, wherein the iodine is contained in an amount of 0.01 to 1.5% by mass based on the elastic copolymer (100% by mass).

<15> a crosslinked rubber article obtained by crosslinking the fluorinated elastic copolymer composition according to any one of <1> to <14 >.

ADVANTAGEOUS EFFECTS OF INVENTION

The fluorinated elastic copolymer composition of the present invention can provide a crosslinked rubber article having excellent low-temperature characteristics and sufficient hardness. The crosslinked rubber article of the present invention is excellent in low-temperature characteristics and has sufficient hardness.

Detailed Description

The meanings and descriptions of the following terms in the present specification are as follows.

"Unit" in the copolymer means a radical derived from 1 molecule of a monomer formed by polymerization of the monomer. The unit may be a radical formed directly by polymerization of a monomer, or may be a radical in which a part of the radical is converted into another structure by treating a polymer.

"etheric oxygen atom" means an oxygen atom forming an ether bond (-O-) between carbon atoms.

The "compound represented by the formula (1)" is described as "compound (1)". Other "compounds represented by the formula" are also described as follows.

The "pressure unit (MPa)" is "gauge pressure (gauge)" unless otherwise specified.

"to" indicating a numerical range means to include the numerical values described before and after the range as the lower limit value and the upper limit value.

< fluorinated elastic copolymer composition >

The fluoroelastomer copolymer composition of the present invention comprises a specific fluoroelastomer copolymer and a specific organosilicon compound. The fluoroelastomer copolymer composition of the present invention preferably further comprises a crosslinking agent. The fluoroelastomer copolymer composition of the present invention preferably further comprises a crosslinking assistant. The elastic fluorocopolymer composition of the present invention may contain other additives, if necessary, within the range not impairing the effects of the present invention.

(fluorinated elastic copolymer)

The elastic fluorocopolymer in the present invention has: a unit based on tetrafluoroethylene (hereinafter, also referred to as TFE) (hereinafter, also referred to as TFE unit), and a unit based on a compound (1) described later (hereinafter, also referred to as PAVE unit). The fluorinated elastic copolymer of the present invention preferably has either or both of a unit based on a compound (2) described later (hereinafter, also referred to as a POAVE unit) and a unit based on a fluorinated monomer having 2 or more polymerizable unsaturated bonds (hereinafter, also referred to as a DVE unit). The elastic fluorocopolymer of the present invention may further have units based on other monomers as necessary within the range not impairing the effects of the present invention.

PAVE units are units based on compound (1).

CF₂＝CFOR^f1(1)

Wherein R is^f1Is a C1-10 perfluoroalkyl group.

R^f1In the above formula, the perfluoroalkyl group may be linear or branched. For R^f1The number of carbon atoms of (b) is preferably 1 to 5, more preferably 1 to 3, from the viewpoint of improving the productivity of the fluorinated elastic copolymer.

Specific examples of the compound (1) include the following compounds. Note that, the parenthesis following the chemical formula is abbreviated as the compound.

CF₂＝CFOCF₃(PMVE)、CF₂＝CFOCF₂CF₃(PEVE)、CF₂＝CFOCF₂CF₂CF₃

(PPVE)、CF₂＝CFOCF₂CF₂CF₂CF₃

As the compound (1), PMVE, PEVE, or PPVE is preferable from the viewpoint of improving the productivity of the fluorinated elastic copolymer as the compound (1) improving the productivity of the fluorinated elastic copolymer.

The POAVE units are units based on compound (2). By providing the fluorinated elastic copolymer with the unit (c), the low-temperature characteristics when the crosslinked rubber article is produced are further excellent.

CF₂＝CF(OCF₂CF₂)_n-(OCF₂)_m-OR^f2(2)

Wherein R is^f2Is perfluoroalkyl group with 1-4 carbon atoms, n is an integer of 0-3, m is an integer of 0-4, and n + m is an integer of 1-7.

R^f2In the above formula, the perfluoroalkyl group may be linear or branched. R^f2The carbon number of (C) is preferably 1 to 3.

When n is 0, m is preferably 3 or 4. When n is 1, m is preferably an integer of 2 to 4. When n is 2 or 3, m is preferably 0. n is preferably an integer of 1 to 3.

R^f2When the number of carbon atoms, n and m are within the above range, the low-temperature characteristics when the fluorinated elastic copolymer is formed into a crosslinked rubber article are more excellent, and the productivity of the fluorinated elastic copolymer is improved.

Specific examples of the compound (2) include the following compounds. Note that, the parenthesis following the chemical formula is abbreviated as the compound.

CF₂＝CF-OCF₂CF₂-(OCF₂)₄-OCF₃(C9PEVE)、

CF₂＝CF-OCF₂CF₂-(OCF₂)₂-OCF₃(C7PEVE)、

CF₂＝CF-(OCF₂CF₂)₂-OCF₂CF₃(EEAVE)、

CF₂＝CF-(OCF₂CF₂)₃-OCF₂CF₃(EEEAVE)

CF₂＝CF-OCF₂-OCF₃、CF₂＝CF-OCF₂-OCF₂-OCF₃

As the compound (2), C9PEVE, C7PEVE, EEAVE or EEEAVE is preferable from the viewpoint of further improving the low-temperature properties when the fluorinated elastic copolymer is formed into a crosslinked rubber article.

These compounds can be produced by the method described in international publication No. 00/56694 using the corresponding alcohol as a raw material.

The DVE unit is a unit based on a fluorine-containing monomer having 2 or more polymerizable unsaturated bonds. By providing the fluoroelastomer copolymer with DVE units, the fluoroelastomer copolymer can maintain the rubber physical properties when made into a crosslinked rubber article, and the fluoroelastomer copolymer has more excellent low-temperature characteristics (TR 10).

Examples of the polymerizable unsaturated bond include a carbon atom-carbon atom double bond (C ═ C) and a triple bond (C ≡ C), and a double bond is preferable. The number of the polymerizable unsaturated bond is preferably 2 to 6, more preferably 2 or 3, and particularly preferably 2.

The fluorine-containing monomer having 2 or more polymerizable unsaturated bonds is preferably a perfluoro compound.

The compound (3) is preferred as the fluorine-containing monomer having 2 or more polymerizable unsaturated bonds, from the viewpoint of maintaining rubber physical properties when the fluorine-containing elastic copolymer is formed into a crosslinked rubber article and further improving low-temperature characteristics (TR 10).

CF₂＝CFOR^f3OCF＝CF₂(3)

Wherein R is^f3The fluorine-containing polymer is a C1-25 perfluoroalkylene group or a group having 1 or more etheric oxygen atoms between carbon atoms of C2-25 perfluoroalkylene groups.

R^f3In the above-mentioned examples, the perfluoroalkylene group may be linear or branched. For R^f3The number of carbon atoms of (b) is preferably 3 or 4, from the viewpoint of maintaining rubber physical properties when the fluorinated elastic copolymer is formed into a crosslinked rubber article and further improving low-temperature characteristics (TR 10).

Specific examples of the compound (3) include the following compounds. Note that, the parenthesis following the chemical formula is abbreviated as the compound.

CF₂＝CFO(CF₂)₂OCF＝CF₂、

CF₂＝CFO(CF₂)₃OCF＝CF₂(C3DVE)、

CF₂＝CFO(CF₂)₄OCF＝CF₂(C4DVE)、

CF₂＝CFO(CF₂)₆OCF＝CF₂、CF₂＝CFO(CF₂)₈OCF＝CF₂、

CF₂＝CFO(CF₂)₂OCF(CF₃)CF₂OCF＝CF₂、

CF₂＝CFO(CF₂)₂O(CF(CF₃)CF₂O)₂CF＝CF₂、

CF₂＝CFOCF₂O(CF₂CF₂O)₂CF＝CF₂、

CF₂＝CFO(CF₂O)₃O(CF(CF₃)CF₂O)₂CF＝CF₂、

CF₂＝CFOCF₂CF(CF₃)O(CF₂)₂OCF(CF₃)CF₂OCF＝CF₂

CF₂＝CFOCF₂CF₂O(CF₂O)₂CF₂CF₂OCF＝CF₂And the like.

The compound (3) is particularly preferably a C3DVE or a C4DVE, from the viewpoint of maintaining the rubber physical properties when the fluorinated elastic copolymer is formed into a crosslinked rubber article and further improving the low-temperature characteristics (TR 10).

The unit (e) is a unit based on other monomers (i.e., monomers other than TFE, compound (1), compound (2), and compound (3)).

Examples of the other monomer include monomers having a fluorine atom and a halogen atom other than a fluorine atom (e.g., bromotrifluoroethylene, iodotrifluoroethylene), monomers having a fluorine atom and a halogen atom other than a fluorine atom, andnitrile group monomer (CF)₂＝CFO(C F₂)₅CN, perfluoro (8-cyano-5-methyl-3, 6-dioxa-1-octene), etc.).

The molar ratio of TFE units to PAVE units (TFE units/PAVE units) is preferably from 35/65 to 90/10, more preferably from 60/40 to 85/15, and still more preferably from 65/35 to 80/20.

The proportion of the TFE unit is preferably 35 to 75 mol%, more preferably 40 to 75 mol%, and still more preferably 55 to 75 mol% of the total units (100 mol%) constituting the fluorinated elastic copolymer.

The proportion of PAVE units is preferably 3 to 57 mol%, more preferably 5 to 50 mol%, and still more preferably 10 to 40 mol% of all units (100 mol%) constituting the fluorinated elastic copolymer.

The proportion of the POAVE units is preferably 0 to 57 mol%, more preferably 2 to 30 mol%, and still more preferably 2 to 20 mol% of the total units (100 mol%) constituting the fluorinated elastic copolymer.

The proportion of DVE units is preferably 0 to 1 mol%, more preferably 0.05 to 0.5 mol%, and still more preferably 0.05 to 0.3 mol% of all units (100 mol%) constituting the fluoroelastomer copolymer.

The proportion of the unit (e) is preferably 0 to 5 mol%, more preferably 0 to 3 mol%, and still more preferably 0 to 2 mol% of all units (100 mol%) constituting the fluorinated elastic copolymer.

When the proportions of the TFE unit, the PAVE unit, the POAVE unit, the DVE unit and the unit (e) are within the above ranges, the rubber properties when the fluorine-containing elastic copolymer is formed into a crosslinked rubber article are good.

The elastic fluorocopolymer in the present invention preferably further contains iodine atoms, because the elastic fluorocopolymer has excellent crosslinkability and the crosslinked rubber articles have more excellent rubber properties. The iodine atom is preferably bonded to the terminal of the polymer chain of the fluorine-containing elastic copolymer. The terminal of the polymer chain is a concept including both the terminal of the main chain and the terminal of the branch chain.

Examples of the method containing iodine include: a method of introducing an iodine-containing unit into the fluorinated elastic copolymer of the present invention by using an iodine-containing monomer such as iodotrifluoroethylene as the unit (e), and a method of using an iodine-containing chain transfer agent such as the compounds (4) and (5) described later.

The content of iodine atoms in the fluorinated elastic copolymer (100 mass%) is preferably 0.01 to 1.5 mass%, more preferably 0.01 to 1.0 mass%. When the content is within the above range, the fluorine-containing elastic copolymer is more excellent in crosslinkability and the crosslinked rubber article is more excellent in rubber properties.

The storage modulus G' of the elastic fluorocopolymer is preferably 100 to 600kPa, more preferably 200 to 500kPa, and still more preferably 200 to 400 kPa. The storage modulus G ' is a measure of the average molecular weight, and a high storage modulus G ' means a high storage modulus G ' and a low storage modulus G ' means a low storage modulus G '. When the storage modulus G' is within the above range, the elastic fluorocopolymer is excellent in processability and the crosslinked rubber article is excellent in rubber properties.

(method for producing fluorinated elastic copolymer)

The fluorinated elastic copolymer in the present invention can be produced by polymerizing a monomer component containing TFE and the compound (1) in the presence of a radical polymerization initiator. The monomer component may contain the compound (2), the compound (3) and other monomers as required.

As the polymerization method, a radical polymerization method is preferable.

Examples of the radical polymerization initiator include a radical polymerization initiator, heating, ionizing radiation irradiation, and the like, and a radical polymerization initiator is preferable in terms of excellent productivity of the elastic fluorocopolymer.

As the radical polymerization initiator, a known radical polymerization initiator can be used.

As the radical polymerization initiator to be used in the emulsion polymerization described later, a water-soluble initiator is preferable. Examples of the water-soluble initiator include inorganic initiators including a system in which a persulfate (e.g., ammonium persulfate, sodium persulfate, and potassium persulfate), hydrogen peroxide, a water-soluble organic peroxide (e.g., disuccinic acid peroxide, dipentanoic acid peroxide, and t-butyl hydroxy peroxide), an organic initiator (e.g., azobisisobutylamidine dihydrochloride), a persulfate or hydrogen peroxide, and a reducing agent such as sodium bisulfite or sodium thiosulfate are combined, and a redox initiator in which a small amount of iron, a ferrite, and silver sulfate are allowed to coexist.

The amount of the radical polymerization initiator is preferably 0.0001 to 5 parts by mass, more preferably 0.001 to 2 parts by mass, per 100 parts by mass of the monomer component.

When a radical polymerization initiator is used, the monomer component is preferably polymerized in the presence of a chain transfer agent.

Examples of the chain transfer agent include alcohols (such as methanol and ethanol), chlorofluorocarbons (such as 1, 3-dichloro-1, 1,2,2, 3-pentafluoropropane and 1, 1-dichloro-1-fluoroethane), hydrocarbons (such as pentane, hexane and cyclohexane), compound (4), compound (5) and thiols (such as t-dodecylmercaptan and n-octadecylmercaptan).

R^f4I₂(4)

R^f4IBr (5)

Wherein R is^f4Is a C1-16 polyfluoroalkylene group.

R^f4In the above-mentioned examples, the polyfluoroalkylene group may be linear or branched. As R^f4Preferably a perfluoroalkylene group.

The chain transfer agent is preferably the compound (4) because it is excellent in the crosslinkability of the fluorinated elastic copolymer and further excellent in the rubber physical properties of the crosslinked rubber article.

Examples of the compound (4) include 1, 4-diiodoperfluorobutane, 1, 6-diiodoperfluorohexane, 1, 8-diiodoperfluorooctane and the like, and 1, 4-diiodoperfluorobutane is preferable from the viewpoint of excellent polymerization reactivity.

The amount of the chain transfer agent is appropriately set based on the chain transfer constant of the chain transfer agent. When the compound (4) is used, it is preferably 0.01 to 5% by mass, more preferably 0.05 to 2% by mass, per 100 parts by mass of the monomer component.

Examples of the polymerization method include emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization, and emulsion polymerization is preferred because of its excellent adjustment of molecular weight and copolymerization composition and productivity.

In the emulsion polymerization method, the monomer component is polymerized in an aqueous medium containing an emulsifier. Examples of the aqueous medium include water and a mixture of water and a water-soluble organic solvent. Examples of the water-soluble organic solvent include t-butanol, propylene glycol, dipropylene glycol monomethyl ether, and tripropylene glycol, and t-butanol or dipropylene glycol monomethyl ether is preferable in terms of not decreasing the polymerization rate of the monomer.

When the aqueous medium contains a water-soluble organic solvent, the dispersibility of the monomer and the dispersibility of the fluorinated elastic copolymer are excellent, and the productivity of the fluorinated elastic copolymer is excellent. The content of the water-soluble organic solvent is preferably 1 to 40 parts by mass, more preferably 3 to 30 parts by mass, per 100 parts by mass of water.

Examples of the emulsifier include anionic emulsifiers, nonionic emulsifiers, cationic emulsifiers, and the like, and anionic emulsifiers are preferable in terms of more excellent mechanical stability and chemical stability of the latex.

Examples of the anionic emulsifier include hydrocarbon emulsifiers (sodium lauryl sulfate, sodium dodecylbenzenesulfonate, etc.), fluorine-containing emulsifiers (ammonium perfluorooctanoate, sodium perfluorooctanoate, ammonium perfluorohexanoate, compound (6), etc.), and the like.

F(CF₂)_pO(CF(X)CF₂O)_qCF(Y)COOA(6)

Wherein X and Y are each a fluorine atom or a linear or branched perfluoroalkyl group having 1 to 3 carbon atoms, A is a hydrogen atom, an alkali metal or NH₄P is an integer of 2 to 10, and q is an integer of 0 to 3.

The following examples are given as the compound (6).

C₂F₅OCF₂CF₂OCF₂COONH₄、

F(CF₂)₃O(CF(CF₃)CF₂O)₂CF(CF₃)COONH₄、

F(CF₂)₃OCF₂CF₂OCF₂COONH₄、

F(CF₂)₃O(CF₂CF₂O)₂CF₂COONH₄、

F(CF₂)₄OCF₂CF₂OCF₂COONH₄、

F(CF₂)₄O(CF₂CF₂O)₂CF₂COONH₄、

F(CF₂)₃OCF₂CF₂OCF₂COONa、

F(CF₂)₃O(CF₂CF₂O)₂CF₂COONa、

F(CF₂)₄OCF₂CF₂OCF₂COONa、

F(CF₂)₄O(CF₂CF₂O)₂CF₂COONa、

F(CF₂)₂OCF₂CF₂OCF₂COONH₄、

F(CF₂)₂O(CF₂CF₂O)₂CF₂COONH₄、

F(CF₂)₂OCF₂CF₂OCF₂COONa、

F(CF₂)₂O(CF₂CF₂O)₂CF₂COONa

As the anionic emulsifier, ammonium perfluorooctanoate and C are preferable₂F₅OCF₂CF₂OCF₂COONH₄、F(CF₂)₄OCF₂CF₂OCF₂COONH₄Or F (CF)₂)₃OCF₂CF₂OCF₂COONH₄。

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

The latex containing the fluorine-containing elastic copolymer can be obtained by emulsion polymerization. The fluoroelastomer copolymer can be separated from the latex by coagulation.

Examples of the agglomeration method include a method using addition of a metal salt, addition of an inorganic acid (e.g., hydrochloric acid), mechanical shearing, freezing and thawing, and the like.

The polymerization conditions for radical polymerization are appropriately selected depending on the monomer composition and the decomposition temperature of the radical polymerization initiator.

The polymerization pressure is preferably 0.1 to 20MPa, more preferably 0.3 to 10MPa, and still more preferably 0.3 to 5 MPa. The polymerization temperature is preferably 0 to 100 ℃, more preferably 10 to 90 ℃, and still more preferably 20 to 80 ℃. The polymerization time is preferably 1 to 72 hours, more preferably 1 to 24 hours, and further preferably 1 to 12 hours.

(organic silicon Compound)

The organosilicon compound in the present invention is an organosilicon compound having a perfluoropolyether chain and 2 or more polymerizable unsaturated bonds.

The organosilicon compound is preferably one having vinylsilyl (CH) groups at both ends of a 2-valent perfluoropolyether chain via a linking group, from the viewpoint of being easily available and having excellent hardness when the crosslinked rubber article is produced₂CHSi), and particularly preferred is compound (7).

Wherein R is¹Is a hydrocarbyl radical having a valence of 1, R²Is a hydrogen atom or a 1-valent hydrocarbon group, R^f7Is a 2-valent perfluoropolyether chain.

As R¹Preferably an alkyl or aryl group, more preferably an alkyl group. R¹The number of carbon atoms of (B) is preferably 1 to 10, more preferably 1 to 8.

As R²Preferably a hydrogen atom, an alkyl group or an aryl group, more preferably a hydrogen atom or an alkyl group. R²The number of carbon atoms of (B) is preferably 1 to 10, more preferably 1 to 8.

As R^f7Examples thereof include the following groups.

-(CF(CF₃)OCF₂)_n1(CF₂OCF(CF₃))_m1-、

-CF₂CF₂OCF₂(CF₂)₂CF₂OCF₂CF₂-、

-CF₂CF₂OCF₂CF(CF₃)OCF₂(CF₂)₂CF₂OCF(CF₃)CF₂OCF₂CF₂-、

-CF₂(OCF₂CF₂)_n2(OCF₂)_m2OCF₂-、

-CF(CF₃)(OCF(CF₃)CF₂)_n3(OCF₂)_m3OCF(CF₃)-、

-CF₂CF₂(OCF₂CF₂CF₂)_n4OCF₂CF₂-

Wherein n1+ m1 is an integer of 2-200, n2 is an integer of 5-50, m2 is an integer of 1-10, n3 is an integer of 5-50, m3 is an integer of 1-10, and n4 is an integer of 5-100.

As the compound (7), the compound (7-1) or the compound (7-2) is preferable in terms of easy availability and excellent hardness when a crosslinked rubber article is produced.

The organosilicon compound can be produced by the method described in Japanese patent No. 3239717.

Examples of commercially available products include SIFEL (trade name of shin-Etsu chemical Co., Ltd.) 2610, 3590N, 3790N, 3405A/B, 3505A/B, 3705A/B, 2618, 2614, 2617, 2661 and 2662.

The proportion of the organosilicon compound is preferably 10 to 40% by mass, more preferably 10 to 35% by mass, and still more preferably 10 to 30% by mass of the total (100% by mass) of the fluorinated elastic copolymer and the organosilicon compound. When the ratio is not less than the lower limit of the above range, the low-temperature properties of the crosslinked rubber article are more excellent. When the above ratio is not more than the upper limit of the above range, the rubber properties of the crosslinked rubber article obtained are excellent.

When the fluorine-containing elastic copolymer composition further contains a crosslinking agent, the crosslinking efficiency becomes high.

Examples of the crosslinking agent include organic peroxides, polyols, amines, triazines, and the like, and organic peroxides are preferable from the viewpoint of excellent productivity, heat resistance, and chemical resistance of the crosslinked rubber article.

Examples of the organic peroxide include dialkyl peroxides (di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α -bis (t-butylperoxy) -p-diisopropylbenzene, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane-3, etc.), 1-bis (t-butylperoxy) -3,3, 5-trimethylcyclohexane, 2, 5-dimethylhexane-2, 5-dihydroperoxide, benzoyl peroxide, t-butylperoxybenzene, 1, 3-bis (t-butylperoxyisopropyl) benzene, 2, 5-dimethyl-2, 5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butyl peroxyisopropylcarbonate, etc., and the dialkyl peroxides are preferable.

The amount of the crosslinking agent to be blended is preferably 0.3 to 10 parts by mass, more preferably 0.3 to 5 parts by mass, and still more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the total of the fluorinated elastic copolymer and the organosilicon compound. When the compounding amount is within the above range, the crosslinked rubber article is excellent in the balance between strength and elongation.

When the fluoroelastomer copolymer composition further contains a crosslinking assistant, the crosslinking efficiency becomes higher. In addition, the hardness of the crosslinked rubber article becomes further high.

Examples of the crosslinking assistant include triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, 1,3, 5-triacryloylhexahydro-1, 3, 5-triazine, triallyl trimellitate, m-phenylenediamine bismaleimide, p-quinone dioxime, p ' -dibenzoyl quinone dioxime, dipropargyl terephthalate, diallyl phthalate, N ', N ", N '" -tetraallyl terephthalamide, vinyl-containing siloxane oligomers (e.g., polymethylvinylsiloxane, polymethylphenylvinylsiloxane), and the like. Among these, triallyl cyanurate, triallyl isocyanurate, or trimethallyl allyl isocyanurate is preferable, and triallyl isocyanurate is particularly preferable.

The amount of the crosslinking assistant to be blended is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the total of the elastic fluorocopolymer and the organosilicon compound. When the compounding amount is within the above range, the crosslinked rubber article is excellent in the balance between strength and elongation.

Examples of the other additives include metal oxides, pigments, fillers, reinforcing materials, and processing aids.

In the case where the fluorine-containing elastic copolymer composition further contains a metal oxide, the crosslinking reaction proceeds rapidly and reliably.

Examples of the metal oxide include oxides of 2-valent metals such as magnesium oxide, calcium oxide, zinc oxide, and lead oxide. The amount of the metal oxide to be blended is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the total of the elastic fluorocopolymer and the organosilicon compound. When the compounding amount is within the above range, the crosslinked rubber article is excellent in the balance between strength and elongation.

Examples of the filler or the reinforcing material include carbon black, titanium oxide, silica, clay, talc, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, a TFE/ethylene copolymer, a TFE/propylene copolymer, and a TFE/vinylidene fluoride copolymer.

The processing aid may be any known processing aid. Examples of the processing aid which exhibits a function as a lubricant include fatty acid metal salts (sodium stearate, calcium stearate, etc.), synthetic waxes (polyethylene wax, etc.), fatty acid esters (glycerol monooleate, etc.), and the like.

The Tg of the elastic fluorocopolymer composition is preferably 0 ℃ or lower, more preferably-4 ℃ or lower. When Tg is within the above range, the low-temperature characteristics when the fluorine-containing elastic copolymer composition is formed into a crosslinked rubber article are further excellent.

The fluorinated elastic copolymer composition of the present invention can be obtained by kneading the fluorinated elastic copolymer, the organosilicon compound, and if necessary, the crosslinking agent, the crosslinking assistant, and other additives by a kneading method using a known kneading apparatus such as a 2-roll kneader, a kneader, and a banbury mixer.

The above-described fluoroelastomer copolymer composition of the present invention contains a fluoroelastomer copolymer and an organosilicon compound having a perfluoropolyether chain and 2 or more polymerizable unsaturated bonds, and therefore can provide a crosslinked rubber article having excellent low-temperature characteristics.

Further, since the elastic fluorocopolymer composition of the present invention contains silicon atoms, a crosslinked rubber article having a sufficient hardness can be obtained as compared with the elastic fluorocopolymer composition containing a fluorinated ether compound not containing silicon atoms, which is described in patent document 1.

< crosslinked rubber articles >

The crosslinked rubber article of the present invention is obtained by crosslinking the fluorinated elastic copolymer composition of the present invention. Examples of the crosslinked rubber articles include crosslinked rubber sheets, O-rings, gaskets (sheet gaskets), oil seals, diaphragms, V-rings, sealing materials for semiconductor devices, chemical-resistant sealing materials, paints, and wire coating materials.

The tensile strength of the crosslinked rubber article when cut is preferably 5MPa or more, more preferably 10MPa or more. The elongation at the time of cutting of the crosslinked rubber article is preferably 100% or more, more preferably 150% or more. The TR10 of the crosslinked rubber article is preferably 0 ℃ or lower, more preferably-5 ℃ or lower.

The type A durometer hardness of the crosslinked rubber article is preferably 60 to 90 degrees, more preferably 65 to 85 degrees.

The crosslinked rubber article of the present invention can be obtained by suitably molding and crosslinking the fluorinated elastic copolymer composition of the present invention by a known method.

Examples of the crosslinking method include a method by heating and a method by irradiation with ionizing radiation. Examples of the molding method include injection molding, extrusion molding, co-extrusion molding, blow molding, compression molding, inflation molding, transfer molding, and calender molding.

In the case where the fluorine-containing elastic copolymer composition contains an organic peroxide as a crosslinking agent, crosslinking by heating is preferable.

As a specific method for producing a crosslinked rubber article obtained by heat crosslinking, for example, a hot press molding method is exemplified. In the hot press molding method, a cavity of a mold having a desired shape is filled with the fluorine-containing elastic copolymer composition using the heated mold, and the molding is performed by heating while crosslinking (hot press crosslinking) is performed, thereby obtaining a crosslinked rubber article. The heating temperature is preferably 130 to 220 ℃, more preferably 140 to 200 ℃, and further preferably 150 to 180 ℃.

In the case of using the hot press molding method, it is also preferable to further heat the crosslinked rubber article obtained by hot press crosslinking (also referred to as primary crosslinking) by an oven or the like using electricity, hot air, steam or the like as a heat source as necessary to perform crosslinking (also referred to as secondary crosslinking). The temperature at the time of secondary crosslinking is preferably 150 to 280 ℃, more preferably 180 to 260 ℃, and further preferably 200 to 250 ℃. The secondary crosslinking time is preferably 1 to 48 hours, more preferably 4 to 24 hours. The secondary crosslinking is sufficiently performed, thereby improving the rubber physical properties of the crosslinked rubber article. In addition, the decomposition and volatilization of the peroxide residue contained in the crosslinked rubber article are reduced. The hot press molding method is preferably applied to molding of a sealing material or the like.

Examples of the ionizing radiation in the method of irradiation with ionizing radiation include electron beams and γ rays. When crosslinking is performed by irradiation with ionizing radiation, the following method is preferred: the elastic fluorocopolymer composition is molded into a desired shape and then crosslinked by irradiation with ionizing radiation. Examples of the molding method include the following methods: coating a suspension solution obtained by dissolving and dispersing a fluorinated elastic copolymer composition in a suitable solvent, and drying the suspension solution to form a coating film; or by extrusion molding the fluorine-containing elastic copolymer composition into a hose (hose) or a wire. The dose of the ionizing radiation is suitably set, and is preferably 1 to 300kGy, more preferably 10 to 200 kGy.

The crosslinked rubber article of the present invention described above is excellent in low-temperature characteristics and has sufficient hardness because it is obtained by crosslinking the fluorinated elastic copolymer composition of the present invention.