JP2015131894A - Fluorine-containing elastomer and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a fluorine-containing elastomer improved in vulcanized adhesion with metals, plastics, elastomers except fluorine-containing elastomers, or the like without sacrificing good physical properties inherent in fluorine-containing elastomers; and a production method thereof.SOLUTION: The fluorine-containing elastomer is formed by copolymerization of an alkali metal perfluorovinyloxy polyether carboxylate represented by the general formula [I] defined by CF=CF[OCFCF(CF)]O(CF)O[CF(CF)CFO]CF(CF)COOM (M is Na or K; a is 1 to 6; and b+c is 0 to 6) in a fluorine-containing copolymer with a copolymerization rate of 0.01 to 0.5 mol%. This fluorine-containing elastomer is produced by a copolymerization reaction of a fluorine-containing monomer in the presence of the alkali metal perfluorovinyloxy polyether carboxylate represented by the general formula [I] as a fluorine-based reactive emulsifier.

Description

  The present invention relates to a fluorine-containing elastomer and a method for producing the same. More specifically, the present invention relates to a fluorine-containing elastomer having excellent vulcanization adhesion and a method for producing the same.

  O-rings, oil seals, packings, gaskets, etc. for automotive parts, general industrial machinery, semiconductors and other chemical plants must have elasticity, heat-resistant chemical stability, chemical resistance, fuel oil resistance, etc. Various types of fluorine-containing elastomers are used in the field where is required.

  Fluorine-containing elastomers are more expensive and have higher functionality than general-purpose elastomers, so their fields of application have been limited, but in recent years, especially in the automotive industry, fuel sealing, heat resistance, chemical The demand for various parts such as stability is increasing, and the use of fluorine-containing elastomer products is increasing. Furthermore, the market demand for higher-functional fluorine-containing elastomers than existing fluorine-containing elastomers is increasing.

  Here, fluorine-containing elastomer products are used as molded products, but most of them are composite products of metals or plastics, and elastomers other than fluorine-containing elastomers. Adhesion between fluorine-containing elastomers and other materials is important. It has become an element. Of these, particularly important is the vulcanization adhesion when the fluorine-containing elastomer and other materials are molded together in the product molding process.

As a method for improving the adhesion between the fluorine-containing elastomer and the metal, the present applicant previously proposed a carboxyl group-containing fluorine-containing copolymer obtained by copolymerizing 0.1 to 5 mol% of α-trifluoromethylacrylic acid. (See Patent Document 1). However, α-trifluoromethylacrylic acid to be copolymerized is not a perfluorinated monomer, and there is a risk of impairing the high heat resistance inherent to the fluorine-containing elastomer in applications where the temperature is high, such as inside an automobile engine. Further, in this prior document, although improvement of adhesion in coating applications has been confirmed, no mention is made of vulcanization adhesion.

Japanese Patent No. 5136535 Japanese Patent Publication No. 3-80145 Japanese Patent Publication No.58-4728 Japanese Patent Publication No.54-1585 Japanese Patent No. 4,617,833

Fluorine Chem. 75, 163-167 (1995)

  An object of the present invention is to provide a fluorine-containing elastomer having improved vulcanization adhesion with metal, plastic, or an elastomer other than the fluorine-containing elastomer without impairing the good physical properties inherent to the fluorine-containing elastomer, and a method for producing the same. There is to do.

Such an object of the present invention is to provide a general formula in a fluorine-containing copolymer.
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _b O (CF ₂ ) _a O [CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOM [I]
Wherein M is sodium or potassium, a is an integer of 1 to 6, preferably 2, and b + c is an integer of 0 to 6, preferably 0 or 1. This is achieved by a fluorine-containing elastomer obtained by copolymerizing an alkali metal oxypolyethercarboxylic acid salt at a copolymerization ratio of 0.01 to 0.5 mol%.
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _b O (CF ₂ ) _a O [CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOM [I]
(Where M is sodium or potassium, a is an integer of 1 to 6, and b + c is an integer of 0 to 6). It is produced by carrying out a copolymerization reaction in the presence of an alkali metal ether carboxylate.

  The fluorine-containing elastomer according to the present invention is obtained by copolymerizing a novel perfluorovinyloxypolyether carboxylic acid alkali metal salt at a copolymerization ratio of 0.01 to 0.5 mol%. It has excellent effects such as exhibiting sulfur adhesion. Therefore, when the fluorine-containing elastomer according to the present invention is used, for example, high adhesiveness can be obtained without forming an adhesive layer on the metal surface, so that it is possible to eliminate the pretreatment of the metal surface. .

  In addition, the perfluorovinyloxypolyether carboxylic acid alkali metal salt represented by the general formula [I] also acts as a fluorine-based reactive emulsifier (surfactant), and thus has been conventionally used in emulsion polymerization of fluorine-containing elastomers. The effects of reducing the amount of the emulsifier and enabling the use of the emulsifier are also exhibited. Further, the fluorine-containing elastomer latex obtained without using a general emulsifier makes it possible to omit complicated coagulation and washing operations in the production process of the fluorine-containing elastomer. In addition, when the washing step is omitted for the fluorine-containing elastomer obtained using the conventionally used emulsifier, deterioration of the physical properties of the fluorine-containing elastomer or reduction of the vulcanization adhesiveness is inevitable. With regard to such a fluorine-containing elastomer, even if the washing step is omitted, no deterioration in physical properties or a decrease in vulcanized adhesiveness is observed.

Perfluorovinyloxypolyether carboxylic acid alkali metal salt copolymerized in the fluorine-containing elastomer copolymer at a ratio of 0.01 to 0.5 mol%, preferably 0.02 to 0.2 mol% is a novel compound represented by the following general formula It is.
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _b O (CF ₂ ) _a O [CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOM [I]
Here, M is sodium or potassium, a is an integer of 1 to 6, preferably 2, and b + c is an integer of 0 to 6, preferably 0 or 1.

The perfluorovinyloxy polyether carboxylic acid alkali metal salt represented by the general formula [I] has the general formula
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _b O (CF ₂ ) _a O [CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOR [II]
Wherein R is an alkyl group having 1 to 12 carbon atoms, a is an integer of 1 to 6, preferably 2, and b + c is an integer of 0 to 6, preferably 0 or 1. The perfluorovinyloxypolyether carboxylic acid alkyl ester represented is produced by hydrolysis or solvolysis in the presence of an alkali metal hydroxide.

Perfluorovinyloxypolyether carboxylic acid alkyl ester [II] used as a raw material for this reaction has the general formula
ROOCCF (CF ₃ ) (OCF ₂ CF (CF ₃ )) _b O (CF ₂ ) _a O (CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOR (III)
The perfluoropolyether dicarboxylic acid alkyl ester represented by the formula (1) is reacted with sodium carbonate, potassium carbonate or the like, and one terminal group is vinylated (Patent Document 2, Non-Patent Document 1). This perfluoropolyether dicarboxylic acid alkyl ester [III] has the general formula
FOCCF (CF ₃ ) (OCF ₂ CF (CF ₃ )) _b O (CF ₂ ) _a O (CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COF (IV)
Perfluoropolyether dicarboxylic acid fluoride represented by the general formula ROH is reacted in the presence of an aliphatic alcohol having 1 to 12 carbon atoms and a metal fluoride such as sodium fluoride represented by the general formula ROH (patent document) 5).

Hydrolysis or solvolysis of the perfluorovinyloxypolyether carboxylic acid alkyl ester [II] is carried out in the presence of an alkali metal hydroxide solution, preferably at a reaction temperature of about -20 to 0 ° C. As the alkali metal hydroxide, sodium hydroxide or potassium hydroxide is used, and it is appropriately selected in consideration of reactivity in the polymerization process (surface activation ability). These are used as an aqueous solution or an alcohol solution, and the alcohol can be used without particular limitation as long as it dissolves an alkali metal hydroxide.
From the viewpoint of safety, preferably an aliphatic alcohol having 1 to 6 carbon atoms, particularly preferably ethanol or isopropyl alcohol is used. As the alcohol, a mixture of methanol, ethanol, and isopropyl alcohol can be used. Here, when the reaction temperature is lower than this, the progress of the reaction becomes slow, while at the high temperature, the excessive decomposition progresses.

  The concentration of the alkali metal hydroxide aqueous solution or alcohol solution is not particularly limited, but it is preferably used at a concentration of about 10 to 20% by weight from the viewpoint of operation in solution. In the case of a dilute solution, the number of reaction solutions increases, resulting in an increase in the size of the reaction vessel and an increase in waste liquid. On the other hand, in the case of a high-concentration solution, poor stirring due to precipitation of reactants may occur. is there. The alkali metal hydroxide is used in a proportion of 0.95 to 1.05 times mol, preferably 0.95 to 1.00 times mol of the carboxylic acid ester. If the alkali metal hydroxide is used in a proportion higher than this, it may cause excessive decomposition.

  The resulting reaction mixture is concentrated in a drying facility such as an evaporator or a conical dryer, but the decarboxylation decomposition reaction proceeds at a certain temperature or higher, and the yield decreases. Drying is performed.

The composition of the fluorine-containing monomer copolymerized with the perfluorovinyloxypolyether carboxylic acid alkali metal salt represented by the general formula [I] is not particularly limited. Examples of the copolymer include vinylidene fluoride-hexafluoropropene. Copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropene copolymer, vinylidene fluoride-tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene-perfluoroalkyl vinyl ether-perfluoro Examples include alkyloxyalkyl vinyl ether copolymers, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, and tetrafluoroethylene-perfluoroalkyloxyalkyl vinyl ether copolymers. It is. These fluorine-containing elastomers generally have a weight average molecular weight Mw (measured in terms of polystyrene by GPC) of about 10,000 to 1,000,000 and Mooney viscosity ML _{1 + 10} (121 ° C.) 5 to 140 in accordance with JIS K6300-1. .

  Here, the perfluorovinyloxy polyether carboxylic acid alkali metal salt represented by the general formula [I] functions not only as a copolymerization monomer of the fluorine-containing elastomer but also as a fluorine-based reactive emulsifier (surfactant). For this reason, in the copolymerization reaction, the other fluorine-containing monomer components are charged into the reactor together with other emulsifiers used as necessary.

In the fluorine-containing elastomer, a saturated or unsaturated bromine-containing and / or iodine compound is preferably used for introducing a crosslinking site and for the purpose of adjusting the molecular weight of the fluorine-containing elastomer copolymer. Examples of such bromine-containing and / or iodine compounds include compounds represented by the general formula XRfX (X is I or Br, Rf is a perfluoroalkylene group having 2 to 8 carbon atoms), such as ICF ₂ CF ₂ CF ₂ Examples include those described in Patent Document 3 such as CF ₂ I, ICF ₂ CF ₂ CF ₂ CF ₂ Br, ICF ₂ CF ₂ Br, etc., and the general formula RfX (Rf is unsaturated having 2 to 8 carbon atoms) A fluorohydrocarbon group, which may have one or more ether bonds in the group, and X is bromine or iodine), for example, CF ₂ = CFOCF ₂ CF ₂ Br, CF ₂ = Examples thereof include those described in Patent Document 4 such as CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ Br, CF ₂ = CFBr, CF ₂ = CHBr, CF ₂ = CFI, and CF ₂ = CHI. Of these, ICF ₂ CF ₂ CF ₂ CF ₂ I, CF ₂ = CFOCF ₂ CF ₂ Br, CF ₂ = CFI, and CF ₂ = CHI are preferably used.

  These iodine-containing and / or bromine compounds are monomers that have high reactivity of radicals generated by radical cleavage of iodine and / or bromine easily by the action of an organic peroxide radical generating source during the polymerization reaction. Is added, and then the reaction is stopped by extracting iodine and / or bromine from iodine-containing and / or bromine compounds. When saturated iodine-containing and / or bromine compounds are used, iodine is added at the molecular ends. And / or a bromine-bonded fluorine-containing elastomer.

  The copolymerization reaction of the fluorine-containing monomer in the presence of the bromine-containing and / or iodine crosslinking point forming compound is performed by a random copolymerization reaction in the presence of a polymerization initiator that is generally performed.

  The fluorine-containing elastomer can be produced by any of aqueous emulsion polymerization and aqueous suspension polymerization, but an emulsion polymerization method is preferably used from the viewpoint of productivity and economy.

  Emulsion polymerization is performed using a water-soluble peroxide such as ammonium persulfate, potassium persulfate, or sodium persulfate as a free radical generator. These water-soluble peroxides can also be used as a redox system in combination with a reducing agent such as sodium sulfite and sodium hydrogen sulfite. As other emulsifiers, known fluorinated carboxylates are used, and the fluorinated carboxylic acid is represented by the general formula Rf-COOH (Rf is a C4-C10 fluorohydrocarbon group or a C3-C12 group. A fluoroalkoxyalkyl group having one or more ether bonds therein), for example, ammonium perfluorooctanoate, ammonium perfluorononanoate, and ammonium perfluoroheptanoate. Further, in order to adjust the pH in the polymerization system, an electrolyte having a buffering capacity such as a phosphate such as sodium hydrogen phosphate or potassium dihydrogen phosphate, or a borate may be allowed to coexist. The polymerization reaction is performed under conditions of a temperature of 0 to 100 ° C. and a pressure of 10 MPa or less.

  The fluorine-containing elastomer obtained by the above reaction is cured by a peroxide crosslinking method. Examples of the organic peroxide used in the peroxide crosslinking method include 2,5-dimethyl-2,5-bis (tertiary butyl peroxy) hexane, 2,5-dimethyl-2,5-bis (tertiary butyl). Peroxy) hexyne-3, benzoyl peroxide, bis (2,4-dichlorobenzoyl) peroxide, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, tert-butyl peroxybenzene, 1 , 1-Bis (tert-butylperoxy) -3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxyperoxide, α, α'-bis (tert-butylperoxy)- p-Diisopropylbenzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxyisopropyl carbonate, etc. Is preferably 2,5- Methyl-2,5-bis (t-butylperoxy) hexane, approximately 0.1 to 10 parts by weight per 100 parts by weight of fluoroelastomer, preferably used in a ratio of about 0.5 to 5 parts by weight.

  For peroxide crosslinking, preferably tri (meth) allyl isocyanurate, tri (meth) allyl cyanurate, triallyl trimellitate, N, N'-m-phenylenebis, which is a multifunctional unsaturated compound co-crosslinking agent. Maleimide, diallyl phthalate and the like can be used at a ratio of about 0.1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight, per 100 parts by weight of the fluorine-containing elastomer, if necessary. By using a co-crosslinking agent in combination, a vulcanized product having excellent vulcanization characteristics, mechanical strength, compression set resistance, and the like can be obtained. When the co-crosslinking agent is used in a smaller proportion, the crosslinking density is low and the compression set resistance may be lowered. On the other hand, when the co-crosslinking agent is used in a larger proportion, the elongation is lowered. Here, the tri (meth) allyl group refers to a triallyl group or a trimethallyl group.

  In addition, hydrotalcite compounds, divalent metal oxides or hydroxides such as calcium, magnesium, lead, zinc and other oxides or hydroxides as acid acceptors are about 2 weights per 100 parts by weight of the fluorine-containing elastomer. Part or more, preferably about 3 to 20 parts by weight. If the acid acceptor is used in a smaller ratio, the corrosion resistance to the metal is impaired.

  Further, even when the obtained fluorine-containing elastomer does not have a crosslinking group capable of peroxide vulcanization, vulcanization molding by a polyol vulcanization method can be performed.

  As polyol vulcanizing agents, 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 2,2-bis (4-hydroxyphenyl) perfluoropropane [bisphenol AF], hydroquinone, catechol, resorcin, 4 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylsulfone, 2,2-bis (4-hydroxyphenyl) butane, etc., preferably bisphenol A, bisphenol AF, hydroquinone Etc. are used. These may also be in the form of alkali metal salts or alkaline earth metal salts. These vulcanizing agents are used in a proportion of about 0.5 to 10 parts by weight, preferably about 1 to 5 parts by weight, per 100 parts by weight of the fluorine-containing elastomer.

  Further, as a vulcanization accelerator, a quaternary onium salt (quaternary ammonium salt, quaternary phosphonium salt) is used in an amount of about 0.1 to 30 parts by weight, preferably about 0.2 to 20 parts by weight per 100 parts by weight of the fluorine-containing elastomer. It can also be used in the ratio.

  These vulcanized components can be directly blended into the fluorine-containing elastomer or diluted with carbon black, silica, clay, talc, diatomaceous earth, barium sulfate, etc., or used as a masterbatch dispersion with the fluorine-containing elastomer. Can do.

  In the composition comprising the above components, other compounding agents such as reinforcing agents, fillers, processing aids, anti-aging agents, lubricants, plasticizers, pigments and the like are further added as necessary. Here, when carbon black is used as a filler or reinforcing agent, it is generally used at a ratio of about 10 to 50 parts by weight per 100 parts by weight of the fluorine-containing elastomer. In addition, the addition of bituminous fine powder improves the compression set resistance and can extend the life of sealing materials, etc. by improving heat resistance. The effect of making it possible to further improve the transpiration of automobile fuel or the like to be sealed is achieved.

  Each of the above components is kneaded using a commonly used mixing method such as roll mixing, kneader mixing, Banbury mixing, solution mixing, etc., and then vulcanized and molded. The vulcanization is carried out by press vulcanization at 100 to 250 ° C. for about 1 to 60 minutes, preferably further by oven vulcanization (secondary vulcanization) within about 30 hours at about 150 to 300 ° C.

  Next, the present invention will be described with reference to examples.

Reference Example Methyl 2,3,3,3-tetrafluoro-2- [1,1,2,2-tetrafluoro-2- (1,2,2-trifluorovinyloxy) ethoxy] propanoate prepared according to a conventional method
CF ₂ = CFO (CF ₂ ) ₂ OCF (CF ₃ ) COOCH ₃ (a = 2, b = 0, c = 0)
5 ml of an ethanol solution of 5.19 g (13.3 mmol) was cooled to −10 ° C. or lower using ice and salt. Subsequently, 5 ml of an ethanol solution of potassium hydroxide (purity 85 wt%, concentration 0.90 g / 13.6 mmol) was slowly added dropwise to the cooled ethanol solution up to -10 ° C. After 8 hours, ethanol was removed by an evaporator, and 4.90 g of a waxy white solid was obtained.

As a result of ¹ H-NMR measurement, the signal indicating methyl ester disappeared, and in ¹⁹ F-NMR measurement, the methine signal of —CF (CF ₃ ) — was shifted. , 3-Tetrafluoro-2- [1,1,2,2-tetrafluoro-2- (1,2,2-trifluorovinyloxy) ethoxy] potassium propanoate
CF ₂ = CFO (CF ₂ ) ₂ OCF (CF ₃ ) COOK (a = 2, b = 0, c = 0)
It was judged that
¹⁹ F-NMR (CFCl ₃ , CD ₃ OD solvent):
δ (ppm): -134.75, -134.11 (m, 1F, F ₂ C = C F- )
-124.53, -124.44 (m, 1F, -C F CF _3- )
-121.82, -121.08 (m, 1F, E- F C = CF-)
-114.31, -113.77 (m, 1F, Z- F C = CF-)
-89.28 (s, 2F, = CFOC F _2- )
-87.08, -83.74 (dd, 2F, -C F ₂ OCFCF _3- )
-81.22 (s, 3F, -CFC F _3- )

Example 1
In a 10L stainless steel pressure vessel with stirring blades,
CF ₃ CF ₂ CF ₂ (OCF (CF ₃ ) CF ₂ ) OCF (CF ₃ ) COONH ₄ (Emulsifier) 34 g
CF ₂ = CFO (CF ₂ ) ₂ OCF (CF ₃ ) COOK (fluorine-based reactive emulsifier) 2.4 g
Na ₂ HPO ₄ · 12 hydrate [buffer] 17g
I (CF ₂ ) ₄ I (Chain transfer agent) 27 g
Ion exchange water 5600g
Then, nitrogen substitution was performed to remove oxygen in the reactor, and perfluoro (methyl vinyl ether) CF ₂ = CFOCF ₃ [PMVE] 790 g
670 g of vinylidene fluoride [VdF] / tetrafluoroethylene [TFE] mixed gas
(VdF / TFE = 87.5 mol% / 12.5 mol%)
Was added, and the temperature in the reactor was raised to 50 ° C. The reactor pressure when reaching 50 ° C. was 3.07 MPa · G. After confirming that the temperature was stable, 0.8 g of ammonium persulfate and 0.2 g of sodium hydrogen sulfite were added as an aqueous solution to initiate the polymerization reaction.

  When the polymerization reaction progresses and the pressure in the reactor reaches 3.00 MPa · G, a monomer mixture with a mixing ratio of VdF / TFE / PMVE = 79.6 / 11.4 / 9.0 mol% is introduced, and the pressure is increased to 3.10 MPa · G. I let you. During the polymerization reaction, the pressure in the reactor was maintained at 3.00 to 3.10 MPa · G by introducing a gas having the above composition.

  When the total amount of introduced gases reached 1410 g, the addition was stopped, and when the pressure reached 0.20 MPa · G, the reactor was cooled and the polymerization reaction was stopped. The time required from the introduction of the initiator to the termination of the polymerization was 288 minutes. After completion of the reaction, 8550 g of a fluorine-containing elastomer latex was obtained as a reaction mixture.

The obtained fluorine-containing elastomer latex is poured into the same amount of 1% by weight calcium chloride aqueous solution to agglomerate the latex, then filtered and washed 5 times with 5 times the amount of ion-exchanged water, and dried in a vacuum dryer. 2500 g of VdF / TFE / PMVE / CF ₂ = CFO (CF ₂ ) ₂ OCF (CF ₃ ) COOK copolymer (Mooney viscosity ML _{1 + 10} (121 ° C.) measured according to JIS K6300-1) 26 ) From the measurement result of ¹⁹ F-NMR, the obtained copolymer was confirmed to have the following composition.
VdF 73.6 mol%
TFE 9.5 mol%
PMVE 16.9 mol%
CF ₂ = CFO (CF ₂ ) ₂ OCF (CF ₃ ) COOK 0.03 mol%

In 100 parts by weight of the obtained copolymer,
MT carbon black 37 parts by weight triallyl isocyanurate (Nippon Kasei products TAIC WH60) 4 〃
Organic peroxide (NIPPON OIL & PRODUCTS PERHEXA 25B-40) 1.5 〃
After kneading using an open roll, press vulcanization at 180 ° C for 6 minutes and oven vulcanization at 230 ° C for 22 hours. Normal properties of the resulting vulcanizates (JIS K6253 and JIS K6251) Compliant) and compression set (based on JIS K6262).

  In addition, after joining the unvulcanized fabric before press vulcanization to the zinc phosphate-treated SPCC steel sheet, it was subjected to pressure crosslinking at 180 ° C. for 6 minutes to produce a fluorinated elastomer laminated metal plate. A 90 ° peel test (based on JIS K6256) was performed on the laminated metal plate.

Example 2
In Example 1, instead of CF ₂ = CFO (CF ₂ ) ₂ OCF (CF ₃ ) COOK, CF ₂ = CFOCF ₂ CF ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COOK is used as a copolymer. CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ OCF (CF ₃ ) CF ₂ = CF [OCF ₂ CF (CF ₃ )] _b OCF ₂ CF ₂ O [CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOK (b + c = 1) was obtained using the same amount (2.4 g)
VdF 73.6 mol%
TFE 9.6 mol%
PMVE 16.8mol%
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _b OCF ₂ CF ₂ O [CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOK 0.02 mol%
A copolymer having the following composition (Mooney viscosity ML _{1 + 10} (121 ° C.) 25) was used.

Comparative Example 1
In Example 1, VdF / TFE / PMVE (73.6 / 9.4 / 17.0 molar ratio) copolymer obtained without using CF ₂ = CFO (CF ₂ ) ₂ OCF (CF ₃ ) COOK in the emulsifier component as a copolymer A polymer (Mooney viscosity ML _{1 + 10} (121 ° C.) 29) was used.

The results obtained in the above Examples and Comparative Example 1 are shown in the following table.
table
Measurement Item Example 1 Example 2 Comparative Example 1
Normal properties Hardness (Duro A) 75 75 75
100% modulus (MPa) 5.5 5.4 5.7
Breaking strength (MPa) 19.9 18.0 18.8
Elongation at break (%) 250 270 240
Compression set (3.5mm diameter O-ring use)
200 ℃, 22 hours (%) 26 25 25
200 ℃, 70 hours (%) 32 30 34
90 ° peel test
Peel strength (N / mm) 4.1 3.7 0.2

Comparative Example 2
On the surface of zinc phosphate-treated SPCC steel sheet, a solution prepared by dissolving 4 times the amount of methylethylketone, an adhesive mainly composed of aminosilane and vinylsilane (Lord's product Chemnock AP-133), was applied for 30 minutes at room temperature. After drying, baking was performed at 150 ° C. for 30 minutes, and the unvulcanized dough before press vulcanization obtained in Comparative Example 1 was joined to this adhesive layer-formed metal plate, and 180 ° C. for 6 minutes. The fluorine-containing elastomer laminated metal plate was produced by performing pressure crosslinking. When the 90 ° peel test was conducted on the fluorine-containing elastomer laminated metal plate in the same manner, the peel strength was 1.1 (N / mm).

Claims (6)

In the fluorine-containing copolymer, the general formula
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _b O (CF ₂ ) _a O [CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOM [I]
(Wherein M is sodium or potassium, a is an integer of 1 to 6, and b + c is an integer of 0 to 6). Polymerized fluorine-containing elastomer. In the fluorine-containing copolymer, the general formula
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _b O (CF ₂ ) _a O [CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOM [I´]
(Where M is sodium or potassium, a is 2 and b + c is 0 or 1), and a fluorine-containing elastomer copolymerized with an alkali metal perfluorovinyloxypolyethercarboxylic acid salt .   The fluorine-containing elastomer according to claim 1 or 2, wherein a perfluorovinyloxy polyether carboxylic acid alkali metal salt is copolymerized at a copolymerization ratio of 0.01 to 0.5 mol%. Fluorine-containing monomer is represented by the general formula
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _b O (CF ₂ ) _a O [CF (CF ₃ ) CF ₂ O] _c CF (CF ₃ ) COOM [I]
(Where M is sodium or potassium, a is an integer of 1 to 6, and b + c is an integer of 0 to 6). The method for producing a fluorine-containing elastomer according to claim 1, wherein the copolymerization reaction is carried out in the presence of an alkali metal ether carboxylate.   5. The content of claim 4, wherein the alkali metal perfluorovinyloxypolyethercarboxylate [I] is charged into the reactor together with another emulsifier prior to the supply of the other fluorine-containing monomer component. A method for producing a fluorine elastomer. A fluorine-containing elastomer composition comprising the fluorine-containing elastomer according to claim 1, an organic peroxide, and a polyfunctional unsaturated compound co-crosslinking agent.