JP2018044078A - Fluorine-containing elastic copolymer composition and crosslinked rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorine-containing elastic copolymer composition that makes it possible to obtain a crosslinked rubber having reduced compression set, where the crosslinked rubber can be colored black as well as other colors; and a crosslinked rubber that has reduced compression set and can be colored black as well as other colors.SOLUTION: The present invention provides a fluorine-containing elastic copolymer composition containing a fluorine-containing elastic copolymer having an iodine atom, an ethylene-propylene-nonconjugated diene copolymer, and an organic peroxide; and a crosslinked rubber obtained by crosslinking of the fluorine-containing elastic copolymer composition.SELECTED DRAWING: None

Description

  The present invention relates to a fluorinated elastic copolymer composition and a crosslinked rubber obtained by crosslinking the same.

  Crosslinked rubber obtained by crosslinking a fluorinated elastic copolymer is excellent in heat resistance, chemical resistance, oil resistance, weather resistance, etc., so it is suitable for use in harsh environments where hydrocarbon materials cannot withstand. ing. As the fluorinated elastic copolymer, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-propylene copolymer, tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer and the like are known.

Since the fluorine-containing elastic copolymer is expensive, a fluorine-containing elastic copolymer composition obtained by blending a fluorine-containing elastic copolymer and an inexpensive ethylene-propylene-nonconjugated diene copolymer has been proposed ( Patent Document 1).
It is also known that the compression set of a crosslinked rubber is improved by blending a fluorinated elastic copolymer and an ethylene-propylene-nonconjugated diene copolymer (Patent Document 2).

Japanese Patent No. 4524977 JP 2009-29892 A

  Some fluorine-containing elastic copolymers such as a tetrafluoroethylene-propylene copolymer have a black to brown color before being colored with a coloring component. Therefore, when the fluorinated elastic copolymer composition is colored in a bright color other than black (white, red, blue, yellow, a mixed color thereof, etc.), the color is dull and the desired color cannot be obtained. Therefore, the fluorinated elastic copolymer composition is usually used in a black color.

  The present invention provides a fluorinated elastic copolymer composition capable of obtaining a crosslinked rubber having reduced compression set and capable of coloring not only black but also other colors; and compression set is reduced, and Provided is a crosslinked rubber that can be colored not only in black but also in other colors.

The present invention has the following aspects.
<1> A fluorine-containing elastic copolymer composition comprising a fluorine-containing elastic copolymer having an iodine atom, an ethylene-propylene-nonconjugated diene copolymer, and an organic peroxide.
<2> The fluorinated elastic copolymer composition according to <1>, further including a coloring component.
<3> The fluorinated elastic copolymer composition according to <1> or <2>, wherein the fluorinated elastic copolymer has a unit based on tetrafluoroethylene and a unit based on propylene.
<4> The fluorinated elastic copolymer has a unit based on the following monomer (a), a unit based on the following monomer (b), and a unit based on the following monomer (c). <1> or <2> fluorinated elastic copolymer composition.
Monomer (a): One or more selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene, and perfluoro (alkyl vinyl ether).
Monomer (b): one or more selected from the group consisting of compounds represented by the following formula (I).
^{CR 1 R 2 = CR 3 -R} 4 -CR 5 = CR 6 R 7 (I)
Provided that R ¹ , R ² , R ³ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom, a fluorine atom or a methyl group, and R ⁴ is a perfluoroalkylene group having 1 to 10 carbon atoms, or It is a group having an etheric oxygen atom between the terminal of a C 1-10 perfluoroalkylene group or between a carbon atom and a carbon atom.
Monomer (c): One or more selected from the group consisting of ethylene and propylene.
<5> A crosslinked rubber obtained by crosslinking the fluorinated elastic copolymer composition according to any one of <1> to <4>.

The fluorinated elastic copolymer composition of the present invention can obtain a crosslinked rubber with reduced compression set and can be colored not only in black but also in other colors.
The crosslinked rubber of the present invention has reduced compression set and can be colored not only in black but also in other colors.

Hereinafter, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas.
Also, 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, and perfluoro (propyl vinyl ether) is PPVE. .
The ethylene-propylene-nonconjugated diene copolymer is referred to as EPDM.

The meanings of the following terms in this specification are as follows.
“Unit” refers to a unit derived from a monomer formed by polymerization of the monomer. The unit may be a unit directly formed by a polymerization reaction of monomers, or may be a unit in which a part of the unit is converted to another structure by treating the polymer.
The “etheric oxygen atom” refers to an oxygen atom that forms an ether bond (—O—) between a carbon atom and a carbon atom.

<Fluorine-containing elastic copolymer composition>
The fluorinated elastic copolymer composition of the present invention contains a fluorinated elastic copolymer having iodine atoms (hereinafter also referred to as copolymer (X)), EPDM, and an organic peroxide.
The fluorinated elastic copolymer composition of the present invention preferably further contains a coloring component (a pigment, a colored filler, a colored reinforcing material, etc.).
The fluorinated elastic copolymer composition of the present invention is a filler or reinforcing material other than a crosslinking aid, a metal oxide, and a coloring component, and a copolymer (X), as long as the effects of the present invention are not impaired. It may contain other components such as other resins.

(Copolymer (X))
Examples of the copolymer (X) include the following.
A VdF-HFP copolymer having an iodine atom (Japanese Patent Laid-Open No. 53-125491).
-TFE-P copolymer having iodine atoms (Japanese Patent Laid-Open No. 5-222130, Japanese Patent No. 5321580, etc.).
A unit based on one or more monomers selected from the group consisting of TFE, HFP, VdF, CTFE and PAVE, and a group consisting of vinyl crotonate, vinyl adipate and 1,4-butanediol divinyl ether Fluorine-containing elastic co-polymer having a unit based on one or more monomers and, if necessary, a unit based on one or more monomers selected from the group consisting of ethylene and propylene and having an iodine atom Combined (International Publication No. 2010/053056).
Fluorine-containing unit having a unit based on the monomer (a) described later, a unit based on the monomer (b) described later, and a unit based on the monomer (c) described later and having an iodine atom Elastic copolymer (hereinafter also referred to as copolymer (X1)).

  The copolymer (X) has a unit based on TFE and a unit based on propylene, and an iodine atom, in terms of excellent mechanical properties, heat resistance, chemical resistance, oil resistance and weather resistance of the crosslinked rubber. A fluorinated elastic copolymer having the following is preferred.

  As the copolymer (X), a copolymer (X1) described later is preferable because a crosslinked rubber having sufficiently reduced compression set can be obtained. Hereinafter, the copolymer (X1) will be described in detail.

(Copolymer (X1))
The copolymer (X1) has an iodine atom and has a unit (A) based on the monomer (a), a unit (B) based on the monomer (b), and a unit based on the monomer (c) ( C).
The copolymer (X1) is a monomer other than the monomer (a), the monomer (b), and the monomer (c) as necessary, as long as the effects of the present invention are not impaired. You may have a unit (D) based on d).

The monomer (a) is at least one selected from the group consisting of TFE, HFP, VdF, CTFE and PAVE.
The monomer (a) is preferably at least one selected from the group consisting of TFE, HFP, VdF, and PAVE, and particularly preferably TFE, from the viewpoint of excellent crosslinking reactivity of the fluorinated elastic copolymer composition.

As PAVE, compound (II) is preferable.
CF ₂ = CF—O—R ^f (II)
However, ^Rf is a group having an etheric oxygen atom between the carbon atom and the carbon atom of the perfluoroalkyl group having 1 to 8 carbon atoms or the perfluoroalkyl group having 2 to 8 carbon atoms.
1-6 are preferable and, as for the carbon atom number of ^Rf , 1-5 are more preferable.

  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.

The monomer (b) is at least one selected from the group consisting of compound (I).
^{CR 1 R 2 = CR 3 -R} 4 -CR 5 = CR 6 R 7 (I)
Provided that R ¹ , R ² , R ³ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom, a fluorine atom or a methyl group, and R ⁴ is a perfluoroalkylene group having 1 to 10 carbon atoms, or It is a group having an etheric oxygen atom between the terminal of a C 1-10 perfluoroalkylene group or between a carbon atom and a carbon atom.

R ¹ , R ² , R ³ , R ⁵ , R ⁶ and R ⁷ are preferably a fluorine atom or a hydrogen atom from the viewpoint of enhancing the crosslinking reactivity of the fluorinated elastic copolymer composition and the heat resistance of the crosslinked rubber. A fluorine atom is particularly preferable.
R ⁴ may be linear or branched, and is preferably linear because the tensile strength and compression set of the crosslinked rubber are further excellent.
The carbon number of R ⁴ is preferably 2 to 8, more preferably 3 to 7, still more preferably 3 to 6, and particularly preferably 3 to 5 in view of further excellent tensile strength and compression set of the crosslinked rubber.
The number of etheric oxygen atoms in R ⁴ is preferably 0 to 3 and more preferably 1 to 2 from the viewpoint that the tensile strength and compression set of the crosslinked rubber are further improved.

As the monomer (b), for example, a compound in which a vinyl group, an allyl group or a butenyl group is bonded to each of both ends of a C 1-10 perfluoroalkylene group directly or via an etheric oxygen atom, etc. Is mentioned.
As the monomer (b), CF ₂ = CFO (CF ₂ ) ₃ OCF = CF from the viewpoint that the cross-linking reactivity of the fluorinated elastic copolymer composition, the tensile strength and the compression set of the cross-linked rubber are further improved. _{2, CF 2 = CFO (CF} 2) 4 OCF = CF 2, CH 2 = CH (CF 2) 6 CH = CH 2 are preferred.

  The monomer (c) is at least one selected from the group consisting of ethylene and propylene. As the monomer (c), propylene is preferable.

Examples of the other monomer (d) include a fluorine-containing monomer, a non-fluorine monomer, and a monomer having an iodine atom.
As the fluorine-containing monomer, vinyl fluoride, pentafluoropropylene, perfluorocyclobutene, (perfluoroalkyl) ethylene (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.) and the like.
Non-fluorinated monomers include α-olefins (isobutylene, pentene, etc.), vinyl ethers (methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl butyrate, caproic acid) Vinyl, vinyl caprylate, etc.).

By having a unit based on a monomer having an iodine atom, an iodine atom can be introduced into the side chain of the copolymer (X1).
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-hexa Fluoro-4-iodopentene, iodotrifluoroethylene, 2-iodoperfluoro (ethyl vinyl ether) and the like can be mentioned.

  The molar ratio [(A) / (C)] of the unit (A) to the unit (C) is preferably 30/70 to 99/1, more preferably 30/70 to 70/30, and 40/60 to 60 / 40 is more preferable. When (A) / (C) is within the above range, the crosslinked rubber is excellent in heat resistance, chemical resistance, oil resistance and weather resistance.

  The proportion of the unit (B) is preferably from 0.1 to 1.5 mol%, more preferably from 0.15 to 0.8 mol%, out of 100 mol% of all the units of the copolymer (X1), and More preferred is 25 to 0.6 mol%. When the proportion of the unit (B) is at least the lower limit of the above range, the crosslink reactivity of the fluorinated elastic copolymer composition is further improved, and the tensile strength and compression set of the crosslinked rubber are further improved. If the proportion of the unit (B) is less than or equal to the upper limit of the above range, it is possible to reliably prevent cracking when stress such as bending is applied at high temperatures while maintaining excellent physical properties as a crosslinked rubber or even more. Can be reduced.

  When the copolymer (X1) further has a unit (D), the proportion of the unit (D) is preferably 0.001 to 2.0 mol% out of 100 mol% of all units of the copolymer (X1). 0.01 to 1.0 mol% is more preferable, and 0.01 to 0.5 mol% is particularly preferable.

  Preferred combinations of the unit (A) and the unit (C) in the copolymer (X1) include the following (x1) to (x4). (X1), (x2), and (x4) are excellent in cross-linking reactivity of the fluorinated elastic copolymer composition and excellent in mechanical properties, heat resistance, chemical resistance, oil resistance and weather resistance of the cross-linked rubber. More preferred is (x1).

(X1): A combination of units based on TFE (hereinafter also referred to as TFE units) and units based on propylene (hereinafter also referred to as P units).
(X2): A combination of TFE units, P units, and units based on VdF (hereinafter also referred to as VdF units).
(X3): A combination of a TFE unit, a P unit, and a unit based on PPVE (hereinafter also referred to as PPVE unit).
(X4): A combination of a TFE unit, a P unit, and a unit based on PMVE (hereinafter also referred to as PMVE unit).

The ratio of each unit in (x1) to (x4) is preferably the following molar ratio. When the proportion of each unit is the following molar ratio, the cross-linking reactivity of the fluorinated elastic copolymer composition is further improved, and the mechanical properties, heat resistance, chemical resistance, oil resistance and weather resistance of the cross-linked rubber are further improved.
(X1): TFE unit / P unit = 40/60 to 60/40 (molar ratio).
(X2): TFE unit / P unit / VdF unit = 40 to 59/59 to 40/1 to 10 (molar ratio).
(X3): TFE unit / P unit / PPVE unit = 30 to 60/10 to 40/10 to 40 (molar ratio).
(X4): TFE unit / P unit / PMVE unit = 30 to 60/10 to 40/10 to 40 (molar ratio).

The iodine atom in the copolymer (X1) is preferably at the end of the copolymer (polymer chain). The term “end of the polymer chain” is a concept including both the end of the main chain and the end of the branched chain.
The content of iodine atoms is preferably 0.01 to 5.0% by mass, more preferably 0.05 to 2.0% by mass, out of 100% by mass of the copolymer (X1). 0% by mass is more preferable. If the content of iodine atoms is within the above range, the cross-linking reactivity of the fluorinated elastic copolymer composition is further improved, and the mechanical properties of the cross-linked rubber are further improved. Moreover, it can fully suppress that a copolymer (X1) exhibits brown from black.

The storage elastic modulus G ′ of the copolymer (X1) 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 elastic modulus G ′ indicates a higher molecular weight of the polymer and a higher density of molecular chain entanglement.
The storage elastic modulus G ′ is a value measured under the conditions of temperature: 100 ° C., amplitude: 0.5 degree, and frequency: 50 times / minute according to ASTM D5289 and D6204.

(Method for producing copolymer (X1))
Copolymer (X1) is, for example, a monomer in the presence of a radical polymerization initiator and an iodo compound represented by RI ₂ (wherein R is an alkylene group having 3 or more carbon atoms or a perfluoroalkylene group). It can manufacture by copolymerizing a body (a), a monomer (b), and a monomer (c).
When the monomer (b) is copolymerized, a part of the polymerizable double bond at both ends of the monomer (b) reacts during the polymerization to obtain a copolymer (X1) having a branched chain. It is done.

RI ₂ is a compound in which iodine atoms are bonded to both ends of an alkylene group having 3 or more carbon atoms or a perfluoroalkylene group.
Since RI ₂ functions as a chain transfer agent, when each monomer is copolymerized in the presence of RI _2, an iodine atom may be bonded to the main chain end and the branched chain end of the copolymer (X1). it can.

Specific examples of RI ₂ include 1,3-diiodopropane, 1,4-diiodobutane, 1,6-diiodohexane, 1,8-diiodooctane, 1,3-diiodoperfluoropropane, 1,4 -Diiodoperfluorobutane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane and the like.
The number of carbon atoms of RI ₂ is 3-8 are preferable.
As RI ₂ , an iodo compound having a perfluoroalkylene group is more preferred, and 1,4-diiodoperfluorobutane is particularly preferred.

The amount of RI ₂ is appropriately adjusted depending on the production amount of the copolymer (X1). The abundance of RI ₂ is preferably 0.005 to 10 parts by mass and more preferably 0.02 to 5 parts by mass with respect to 100 parts by mass of the copolymer (X1).

  Examples of the polymerization method include an emulsion polymerization method, a solution polymerization method, a suspension polymerization method, a bulk polymerization method, and the like. As the polymerization method, it is easy to adjust the molecular weight of the copolymer (X1) and the ratio of each unit, and the productivity is excellent. An emulsion polymerization method for polymerization is preferred.

As the aqueous medium, water or water containing a water-soluble organic solvent is preferable.
Examples of the water-soluble organic solvent include tert-butanol, propylene glycol, dipropylene glycol, dipropylene glycol monomethyl ether, and tripropylene glycol, and tert-butanol, propylene glycol, and dipropylene glycol monomethyl ether are preferable.
When the aqueous medium contains a water-soluble organic solvent, the content of the water-soluble organic solvent is preferably 1 to 50 parts by mass and more preferably 3 to 20 parts by mass with respect to 100 parts by mass of water.

The pH of the aqueous medium is preferably 7 to 14, more preferably 7 to 11, still more preferably 7.5 to 11, and particularly preferably 8 to 10.5. When the pH is at least the lower limit of the above range, the stability of RI ₂ is sufficiently maintained, and the crosslinking reactivity of the copolymer (X1) is sufficiently maintained.
The period during which the pH of the aqueous medium is maintained in the above range is preferably the entire polymerization period from the start of the polymerization to the end of the polymerization, but may not be the entire polymerization period. The period during which the pH is maintained in the above range is preferably 80% or more of the total polymerization period, more preferably 90% or more, and further preferably 95% or more.

  In adjusting the pH, it is preferable to use a pH buffer. Examples of pH buffering agents include inorganic salts. Examples of inorganic salts include phosphates (disodium hydrogen phosphate, sodium dihydrogen phosphate, etc.), carbonates (sodium hydrogen carbonate, sodium carbonate, etc.), and the like. Preferable specific examples of the phosphate include disodium hydrogen phosphate dihydrate, disodium hydrogen phosphate dodecahydrate, and the like.

As the emulsifier, an ionic emulsifier is preferable and an anionic emulsifier is more preferable because the mechanical and chemical stability of the latex of the copolymer (X1) is excellent.
As anionic emulsifiers, hydrocarbon emulsifiers (sodium lauryl sulfate, sodium dodecylbenzenesulfonate, etc.), fluorine-containing alkylcarboxylic acids and salts thereof (ammonium perfluorooctanoate, ammonium perfluorohexanoate, ammonium ω-hydroperfluorooctanoate, etc.) ), Compound (III), CF ₃ O (CF ₂ O) _n CF ₂ COONH ₄ (where n is 2 or 3) and the like are preferable.

F (CF ₂ ) _p O (CF (Z) CF ₂ O) _q CF (Z) COOA (III)
However, Z is a fluorine atom or perfluoroalkyl group having 1 to 3 carbon atoms, A is a hydrogen atom, an alkali metal or NH _4, p is an integer from 1 to 10, q is 0 It is an integer of 3.
p is preferably 1 to 4, and more preferably 1 to 3. q is preferably from 0 to 2, and more preferably from 1 to 2. A is preferably a hydrogen atom, Na or NH ₄ , more preferably NH ₄ .

Specific examples of the compound (III) in which A is NH ₄ include the following.
CF ₃ OCF ₂ CF ₂ OCF ₂ COONH ₄ ,
CF ₃ O (CF ₂ CF ₂ O) ₂ CF ₂ COONH ₄ ,
F (CF ₂ ) ₂ OCF ₂ CF ₂ OCF ₂ COONH ₄ ,
F (CF ₂ ) ₂ O (CF ₂ CF ₂ O) ₂ CF ₂ COONH ₄ ,
CF ₃ O (CF (CF ₃ ) CF ₂ O) ₂ CF (CF ₃ ) COONH ₄ ,
F (CF ₂ ) ₂ O (CF (CF ₃ ) CF ₂ O) ₂ CF (CF ₃ ) COONH ₄ ,
F (CF ₂ ) ₃ O (CF (CF ₃ ) CF ₂ O) ₂ CF (CF ₃ ) COONH ₄ ,
F (CF ₂ ) ₃ OCF ₂ CF ₂ OCF ₂ COONH ₄ ,
F (CF ₂ ) ₃ O (CF ₂ CF ₂ O) ₂ CF ₂ COONH ₄ ,
F (CF ₂ ) ₄ OCF ₂ CF ₂ OCF ₂ COONH ₄ ,
F (CF ₂ ) ₄ O (CF ₂ CF ₂ O) ₂ CF ₂ COONH ₄ ,
CF ₃ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ ,
F (CF ₂ ) ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ ,
_{F (CF 2) 3 OCF (} CF 3) CF 2 OCF (CF 3) COONH 4.
0.01-10 mass parts is preferable with respect to 100 mass parts of an aqueous medium, as for content of an emulsifier, 0.1-5 mass parts is more preferable, and 0.1-2 mass parts is further more preferable.

Examples of the radical polymerization initiator include a water-soluble polymerization initiator and a redox polymerization initiator.
Examples of water-soluble polymerization initiators include persulfates (ammonium persulfate, sodium persulfate, potassium persulfate, etc.), organic polymerization initiators (disuccinic acid peroxide, azobisisobutylamidine dihydrochloride, etc.), and the like. . As the water-soluble polymerization initiator, persulfate is preferable, and ammonium persulfate is more preferable.
0.0001-3 mass% is preferable with respect to the total mass of a monomer, and, as for content of a water-soluble polymerization initiator, 0.001-1 mass% is more preferable.

  Examples of the redox polymerization initiator include a polymerization initiator in which a persulfate and a reducing agent are combined. As the redox polymerization initiator, a polymerization initiator capable of polymerizing each monomer in a polymerization temperature range of 0 ° C to 60 ° C is preferable. Examples of the persulfate include ammonium persulfate and alkali metal salts of persulfate (sodium persulfate, potassium persulfate, etc.). As the persulfate, ammonium persulfate is preferable. Examples of the reducing agent include thiosulfate, sulfite, bisulfite, pyrosulfite, and hydroxymethanesulfinate. As the reducing agent, hydroxymethanesulfinate is preferable, and sodium hydroxymethanesulfinate is particularly preferable.

In the redox polymerization initiator, it is preferable that a small amount of iron, iron salt, silver sulfate or the like coexist as a third component, and it is more preferable that a water-soluble iron salt coexists.
Specific examples of water-soluble iron salts include ferrous sulfate, ferric sulfate, ferrous nitrate, ferric nitrate, ferrous chloride, ferric chloride, ferrous ammonium sulfate, ferric sulfate Ammonium etc. are mentioned.
It is preferable to add a chelating agent to the redox polymerization initiator. As the chelating agent, ethylenediaminetetraacetic acid disodium salt is preferred.

  The amount of persulfate used in the redox polymerization initiator is preferably 0.001 to 3% by mass, more preferably 0.01 to 1% by mass, and further 0.05 to 0.5% by mass in the aqueous medium. preferable. The amount of the reducing agent used in the aqueous medium is preferably 0.001 to 3% by mass, more preferably 0.01 to 1% by mass, and particularly preferably 0.05 to 0.5% by mass. The amount of the third component used is preferably 0.0001 to 0.3% by mass, more preferably 0.001 to 0.1% by mass, and particularly preferably 0.01 to 0.1% by mass in the aqueous medium. The amount of the chelating agent used in the aqueous medium is preferably 0.0001 to 0.3% by mass, more preferably 0.001 to 0.1% by mass, and particularly preferably 0.01 to 0.1% by mass.

Polymerization conditions such as polymerization pressure and polymerization temperature are appropriately selected depending on the monomer composition, the decomposition temperature of the radical polymerization initiator, and the like.
The polymerization pressure is preferably 1.0 to 10 MPaG, more preferably 1.5 to 5.0 MPaG, and still more preferably 2.0 to 4.0 MPaG. When the polymerization pressure is at least the lower limit of the above range, the polymerization rate is sufficiently maintained, the reaction is easily controlled, and the productivity is excellent. If the polymerization pressure is less than or equal to the upper limit of the above range, it can be produced with a generally used inexpensive polymerization facility.

The polymerization temperature is preferably 0 to 60 ° C, more preferably 10 to 50 ° C, and still more preferably 20 to 40 ° C. When the polymerization temperature is within the above range, the copolymer (X1) having excellent crosslinking reactivity can be easily obtained, and the mechanical properties of the crosslinked rubber are excellent.
The polymerization rate is preferably 10 to 100 g / L · hour, more preferably 5 to 70 g / L · hour, and further preferably 30 to 50 g / L · hour. If the polymerization rate is equal to or higher than the lower limit of the above range, it is practical productivity. If the polymerization rate is not more than the upper limit of the above range, the molecular weight of the copolymer (X1) will be sufficiently high and the crosslinking reactivity will be excellent.

Examples of the method for isolating the copolymer (X1) obtained by the emulsion polymerization method from the reaction solution include a method of aggregating by a known method. As a coagulation method, a method of salting out by adding a metal salt to a reaction solution containing latex; a method of adding an inorganic acid such as hydrochloric acid to a reaction solution containing latex; a method of mechanically shearing a reaction solution containing latex A method of freezing and thawing a reaction solution containing latex;
The isolated copolymer (X1) is preferably dried using a drying apparatus such as an oven. The drying temperature is preferably 60 to 150 ° C, more preferably 80 to 120 ° C. When the drying temperature is within the above range, the cross-linking reactivity of the dried copolymer (X1) is further improved, and the mechanical properties of the cross-linked rubber are further improved.

(EPDM)
EPDM has units based on ethylene (hereinafter also referred to as E units), P units and units based on non-conjugated dienes.
EPDM may have units based on monomers other than E units, P units, and non-conjugated dienes as necessary, as long as the effects of the present invention are not impaired.

  As the non-conjugated diene, a non-conjugated diene having no fluorine atom is preferable, and ethylidene norbornene (hereinafter referred to as ENB) and dicyclopentadiene are more preferable.

The proportion of E units is preferably 40 to 70% by mass, more preferably 45 to 65% by mass, and still more preferably 48 to 60% by mass, out of 100% by mass of all units of EPDM.
The proportion of units based on non-conjugated diene is preferably 2 to 15% by mass, more preferably 3 to 12.5% by mass, and still more preferably 4 to 10.5% by mass, based on 100% by mass of all units of EPDM.

As the EPDM, liquid to solid EPDM is preferable.
The Mooney viscosity ML _{1 + 4} (100 ° C.) of EPDM is preferably 5 to 90, more preferably 5 to 65, and still more preferably 5 to 55.
When the Mooney viscosity ML _{1 + 4} (100 ° C.) of EPDM is low, a fluorinated elastic copolymer composition having excellent moldability can be obtained. In this case, the Mooney viscosity ML _{1 + 4} (100 ° C.) of EPDM is preferably 5 to 30, more preferably 5 to 20, and still more preferably 5 to 15.

(Organic peroxide)
The organic peroxide is a component that crosslinks the fluorinated elastic copolymer or EPDM.
Organic peroxides 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. As the organic peroxide, dialkyl peroxides are preferable.

  Dialkyl peroxides include di-tert-butyl peroxide, tert-butyl cumyl peroxide, dicumyl peroxide, α, α-bis (tert-butylperoxy) -p-diisopropylbenzene, 2,5-dimethyl-2,5- Examples include di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) -3-hexyne and the like.

(Coloring ingredients)
Examples of the coloring component include pigments, colored fillers, colored reinforcing materials and the like.
Coloring components include carbon black, barium sulfate, titanium oxide, silica, clay, talc, bengara, zinc white, alumina, calcium carbonate, magnesium carbonate, mica, wollastonite, other inorganic colorants, azo pigments, phthalocyanine pigments And the like, and the like.

(Other ingredients)
The crosslinking aid is a component that improves the crosslinking reactivity of the fluorinated elastic copolymer composition.
Cross-linking aids 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, containing vinyl group Examples thereof include siloxane oligomers (polymethylvinylsiloxane, polymethylphenylvinylsiloxane, etc.). As the crosslinking aid, triallyl cyanurate, triallyl isocyanurate, and trimethallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

A metal oxide is a component that causes a crosslinking reaction to proceed rapidly and reliably as an acid-accepting material.
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 the filler or reinforcing material other than the coloring component include glass fibers, aramid fibers, and glass beads.
Examples of other resins include polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, E-TFE copolymer, TFE-VdF copolymer, and the like.

  The fluorinated elastic copolymer composition preferably does not contain an anti-aging agent for EPDM. When the fluorinated elastic copolymer composition contains an anti-aging agent for EPDM, the compatibility with the fluorinated elastic copolymer composition is poor and often causes a bloom failure of the crosslinked rubber.

(Amount of each component)
1-300 mass parts is preferable with respect to 100 mass parts of copolymer (X), and, as for the compounding quantity of EPDM, 5-200 mass parts is more preferable, and 10-100 mass parts is further more preferable. If the blending amount of EPDM is not less than the lower limit of the above range, the effect of EPDM is sufficiently exhibited. If the blending amount of EPDM is less than or equal to the upper limit of the above range, the amount of gas generated when producing a crosslinked rubber is reduced.

  The compounding amount of the organic peroxide is preferably 0.3 to 10 parts by mass, more preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of the total amount of the copolymer (X) and EPDM. 5-3 mass parts is more preferable. If the blending amount of the organic peroxide is within the above range, the crosslinking rate is appropriate, and the tensile strength and compression set of the crosslinked rubber are further improved.

  The blending amount of the coloring component is preferably 1 to 300 parts by mass, more preferably 2 to 200 parts by mass, and further preferably 5 to 100 parts by mass with respect to 100 parts by mass of the total amount of the copolymer (X) and EPDM. .

  0.1-20 mass parts is preferable with respect to 100 mass parts of total amounts of copolymer (X) and EPDM, as for the compounding quantity of a crosslinking adjuvant, 1-10 mass parts is more preferable, 2-10 mass parts Is more preferable. When the blending amount of the crosslinking aid is within the above range, the crosslinking rate is appropriate, and the tensile strength and compression set of the crosslinked rubber are further improved.

(Mechanism of action)
Since the fluorinated elastic copolymer composition of the present invention described above contains EPDM, a crosslinked rubber having a reduced compression set is obtained compared to a crosslinked rubber obtained by crosslinking only the fluorinated elastic copolymer. be able to.
Further, in the fluorinated elastic copolymer composition of the present invention described above, since the fluorinated elastic copolymer has iodine atoms, it has excellent crosslinking reactivity, and the fluorinated elastic copolymer is black to brown. Is suppressed. Therefore, even when the fluorinated elastic copolymer composition is colored in a bright color other than black (white, red, blue, yellow, a mixed color thereof, etc.), the color is not dull and the target color is can get.

<Crosslinked rubber>
The crosslinked rubber of the present invention is obtained by crosslinking the fluorinated elastic copolymer composition of the present invention.

The compression set of the crosslinked rubber of the present invention is preferably 30% or less, more preferably 25% or less, further preferably 20% or less, and particularly preferably 15% or less. The lower limit of the compression set is not particularly limited, and is preferably 0%.
The compression set is measured under conditions of 100 ° C. and 70 hours in accordance with JIS K 6262: 2013 (corresponding international standards ISO 815-1: 2008 and ISO 815-2: 2008).

The tensile strength of the crosslinked rubber of the present invention is preferably 8 MPa or more, more preferably 10 MPa or more, and further preferably 12 MPa or more. The upper limit value of the tensile strength is not particularly limited, and is about 100 MPa, for example.
The tensile strength was measured at 25 ° C. according to JIS K 6251: 2010 (corresponding international standard ISO 37: 2005), by forming a crosslinked rubber into a sheet with a thickness of 2 mm, punching out with a No. 3 dumbbell. The

(Method for producing crosslinked rubber)
The crosslinked rubber is prepared by preparing a fluorinated elastic copolymer composition containing the copolymer (X), EPDM, organic peroxide, and if necessary, a coloring component, a crosslinking aid and the like, and heating the composition. Thus, the copolymer (X) and EPDM can be produced by crosslinking with an organic peroxide.

Examples of an apparatus for mixing each material when preparing the fluorinated elastic copolymer composition include rubber mixing apparatuses such as rolls, kneaders, Banbury mixers, and extruders.
Examples of the molding method of the fluorinated elastic copolymer composition include a compression molding method, an injection molding method, an extrusion molding method, and a calendar molding method. A fluorinated elastic copolymer composition dissolved in a solvent may be applied to the surface of the substrate by dipping, coating or the like.

Examples of the crosslinking method of the fluorinated elastic copolymer composition include various methods such as hot press crosslinking, steam crosslinking and hot air crosslinking. The crosslinking method is appropriately selected in consideration of the shape and use of the molded body. The crosslinking temperature is preferably 100 to 400 ° C. The crosslinking time is preferably several seconds to 24 hours.
The fluorinated elastic copolymer composition may be cross-linked at the same time as molding the fluorinated elastic copolymer composition by a method of hot pressing the fluorinated elastic copolymer composition; After that, the molded body may be crosslinked.

  It is preferable that the crosslinked rubber obtained by heating the fluorinated elastic copolymer composition for primary crosslinking is further heated for secondary crosslinking. Secondary crosslinking can stabilize or improve the mechanical properties, compression set, and other properties of the crosslinked rubber. The heating conditions for secondary crosslinking are preferably 100 to 300 ° C. for 30 minutes to 48 hours.

  As a method of crosslinking the fluorinated elastic copolymer composition, a method of irradiating radiation is also preferable. 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. In the case of crosslinking by irradiation, the fluorinated elastic copolymer composition may be a composition containing no organic peroxide.

(Mechanism of action)
In the crosslinked rubber of the present invention described above, since the fluorinated elastic copolymer composition of the present invention is crosslinked, compression set is reduced, and not only black but also other colors are colored. it can.

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
Examples 1 to 6 are examples, and example 7 is a comparative example.

<Measurement / Evaluation>
(Percentage of each unit)
The proportion of TFE units in the fluorinated elastic copolymer was calculated by fluorine content analysis. Moreover, the ratio of the unit based on vinyl ether was computed by the infrared absorption spectrum.

(Iodine atom content)
The content of iodine atoms in the fluorinated elastic copolymer was quantified with an apparatus combining an automatic sample combustion apparatus (pretreatment apparatus for ion chromatography) (AQF-100, manufactured by Dia Instruments) and an ion chromatograph. .

(Storage modulus G ')
About a fluorine-containing elastic copolymer, according to ASTM D5289 and ASTM D6204 using a rubber processing analyzer (manufactured by Alpha Technologies, RPA2000), temperature: 100 ° C., amplitude: 0.5 degree, frequency: 50 times / The value measured under the condition of minutes was defined as the storage elastic modulus G ′.

(Coloring)
About the fluorine-containing elastic copolymer composition, the color colored visually was determined.

(Preparation of test piece)
The fluorine-containing elastic copolymer composition is subjected to hot pressing (primary crosslinking) at 170 ° C. for 10 minutes, and then subjected to secondary crosslinking for 4 hours in an oven at 120 ° C. to form a crosslinked rubber sheet having a thickness of 2 mm. Got. A crosslinked rubber sheet was punched out with a No. 3 dumbbell to prepare a test piece.

(Hardness)
About the test piece, the type A durometer hardness was measured according to JIS K 6253-1: 2012 (corresponding international standard ISO 18517: 2005).

(Tensile strength)
About the test piece, the tensile strength was measured according to JIS K 6251: 2010 (corresponding international standard ISO 37: 2005).

(100% tensile stress)
About the test piece, the tensile stress at 100% elongation was measured according to JIS K 6251: 2010 (corresponding international standard ISO 37: 2005).

(Elongation)
About the test piece, the elongation tensile stress at break was measured according to JIS K 6251: 2010 (corresponding international standard ISO 37: 2005).

(specific gravity)
About the test piece, specific gravity was measured according to JISK6220-1 using the specific gravity meter (made by Shinko Denshi).

(Compression set)
The fluorine-containing elastic copolymer composition was subjected to hot pressing (primary crosslinking) at 170 ° C. for 10 minutes, and then subjected to secondary crosslinking in an oven at 120 ° C. for 4 hours. The diameter was 30 mm and the height was 13 mm. A molded body made of a cylindrical crosslinked rubber was obtained. Using the molded body as a measurement sample, a compression set test is performed under conditions of 100 ° C. and 70 hours in accordance with JIS K 6262: 2013 (corresponding international standards ISO 815-1: 2008 and ISO 815-2: 2008). Permanent strain was measured.

<Each component>
(Fluorine-containing elastic copolymer)
Fluorine-containing elastic copolymer A:
As the copolymer (X1), a fluorinated elastic copolymer A was produced.
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, CF ₂ ═CFO (CF ₂ ) ₃ OCF═CF ₂ (hereinafter referred to as C3DVE) ) And 6 g of ammonium persulfate were added. Further, an aqueous solution in which 0.4 g of ethylenediaminetetraacetic acid disodium salt dihydrate and 0.3 g of ferrous sulfate heptahydrate were dissolved in 100 g of ion exchange water was added to the reactor. At this time, the pH of the aqueous medium in the reactor was 9.5.
Then, a monomer mixed gas of TFE / P = 88/12 (molar ratio) was injected at 25 ° C. so that the internal pressure of the reactor was 2.50 MPaG. 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 a latex of fluorinated elastic copolymer A 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, the latex of the fluorinated elastic copolymer A was agglomerated, and the fluorinated elastic copolymer A was precipitated. The fluorinated elastic copolymer A was collected by filtration. Next, the fluorinated elastic copolymer A was washed with ion-exchanged water and dried in an oven at 100 ° C. for 15 hours to obtain 980 g of a white fluorinated elastic copolymer A.

In the infrared absorption spectrum of the fluorinated elastic copolymer A, absorption based on a carbon-carbon double bond was confirmed in the vicinity of 1700 cm ⁻¹ .
The ratio of each unit in the fluorinated elastic copolymer A was TFE unit / unit based on C3DVE / P unit = 56 / 0.2 / 43.8 (molar ratio). The content of iodine atoms in the fluorinated elastic copolymer A was 0.50% by mass. The storage elastic modulus G ′ of the fluorinated elastic copolymer A was 310 kPa.

Fluorine-containing elastic copolymer B: TFE-P copolymer having an iodine atom (Asahi Glass Co., Ltd., AFLAS (registered trademark) 400E, TFE unit / P unit = 56/44 (molar ratio)).
Fluorine-containing elastic copolymer C: TFE-P copolymer having no iodine atom (Asahi Glass Co., Ltd., AFLAS (registered trademark) 150P, TFE unit / P unit = 56/44 (molar ratio)).

(EPDM)
EPDM A: E-P-ENB copolymer (manufactured by Sumitomo Chemical Co., Ltd., ESPRENE (registered trademark) 501A, E unit = 52% by mass, unit based on ENB = 4.0% by mass, Mooney viscosity ML _{1 + 4} (100 ° C.) : 44).

(Organic peroxide)
Organic peroxide A: 1,3-bis (tert-butylperoxyisopropyl) benzene (manufactured by Kayaku Akzo, Parkardox 14).
Organic peroxide B: 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane (manufactured by NOF Corporation, Perhexa (registered trademark) 25B).

(Coloring ingredients)
Coloring component A: MT carbon (manufactured by Cancarb).
Coloring component B: barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.).

(Crosslinking aid)
Crosslinking aid A: Powder type crosslinking aid (Nippon Kasei Co., Ltd., TAIC (registered trademark) WH-60, powder type in which TAIC (registered trademark) is impregnated in white carbon 60%).
Crosslinking aid B: triallyl isocyanurate (manufactured by Nippon Kasei Co., Ltd., TAIC (registered trademark)).

<Preparation of fluorinated elastic copolymer composition>
(Examples 1-7)
Each component of the composition shown in Table 1 was kneaded with two rolls at room temperature for 10 minutes to obtain a uniformly mixed fluorinated elastic copolymer composition.
Using the fluorinated elastic copolymer composition, a test piece and a molded article of a crosslinked rubber were prepared by the above-described method, and each evaluation was performed. The results are shown in Table 1.

In each of Examples 1 to 7, since EPDM was contained, the compression set was small. In particular, Examples 1 to 5 including the copolymer (X1) had a sufficiently low compression set.
Since Examples 1 to 6 contain a fluorine-containing elastic copolymer having an iodine atom which is white, it can be colored in a desired color.
Since Example 7 contains a fluorinated elastic copolymer having a brown color and having no iodine atom, it was attempted to be colored white with barium sulfate, but could not be colored to the desired color (white).

  The crosslinked rubber obtained from the fluorinated elastic copolymer composition of the present invention is suitable for materials such as O-rings, sheets, gaskets, oil seals, diaphragms, and V-rings. In addition, heat-resistant chemical-resistant sealing materials, heat-resistant oil-resistant sealing materials, wire coating materials, semiconductor device sealing materials, corrosion-resistant rubber paints, urea-resistant grease sealing materials, rubber paints, calendar sheets, sponges, rubber rolls, Oil drilling members, heat dissipation sheets, solution cross-linked bodies, rubber sponge bearing seals (urea grease resistant, etc.), linings (chemical resistant), automotive insulation sheets, endoscope packing (amine resistant), mono pumps, bellows hoses (calendar) Sheet processing), water heater packing / valves, fenders (marine civil engineering, ships), textiles / nonwoven fabrics (protective clothing, etc.), base seals, rubber gloves, food container packing, water bottle packing, etc. Is also applicable.

Claims (5)

A fluorine-containing elastic copolymer having an iodine atom;
An ethylene-propylene-nonconjugated diene copolymer;
A fluorine-containing elastic copolymer composition comprising an organic peroxide.   The fluorinated elastic copolymer composition according to claim 1, further comprising a coloring component.   The fluorinated elastic copolymer composition according to claim 1 or 2, wherein the fluorinated elastic copolymer has units based on tetrafluoroethylene and units based on propylene. The fluorinated elastic copolymer has units based on the following monomer (a), units based on the following monomer (b), and units based on the following monomer (c). Or the fluorine-containing elastic copolymer composition of 2.
Monomer (a): One or more selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene, and perfluoro (alkyl vinyl ether).
Monomer (b): one or more selected from the group consisting of compounds represented by the following formula (I).
^{CR 1 R 2 = CR 3 -R} 4 -CR 5 = CR 6 R 7 (I)
Provided that R ¹ , R ² , R ³ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom, a fluorine atom or a methyl group, and R ⁴ is a perfluoroalkylene group having 1 to 10 carbon atoms, or It is a group having an etheric oxygen atom between the terminal of a C 1-10 perfluoroalkylene group or between a carbon atom and a carbon atom.
Monomer (c): One or more selected from the group consisting of ethylene and propylene.   Crosslinked rubber which the fluorinated elastic copolymer composition as described in any one of Claims 1-4 bridge | crosslinked.