JPH07173204A - Production of fluoroelastomer - Google Patents

Abstract

PURPOSE: To easily obtain a fluorine-containing elastomer having a good heat resistance, oil resistance, drug resistance, etc., by safely and efficiently carrying out polymerization reaction without using as a solvent any fluorocarbon solvent which destroys the ozone layer.

CONSTITUTION: When preparing a fluorine-containing elastomer comprising a vinylidene fluoride unit and at least one other fluorine-containing monomer unit which is copolymerizable with this through suspension polymerization, a monomer is dispersed in an aqueous medium containing, against 100 pts.wt. aqueous medium, from 0.001 to 3 pts.wt. suspension stabilizer. Against 100 pts.wt. this aqueous medium, from 0.001 to 5 pts.wt. oil-soluble organic peroxide is diluted with a halogen-free water-soluble hydrocarbon solvent of the formula: R₁-OH, R₂-COO-R₁ or R₁-CO-R₃ (wherein R₁ and R₃ are each a methyl group or a tert-butyl group; and R₂ is a hydrogen atom, a methyl group or a tert-butyl group) to a concentration of from 0.1 to 75 wt.% to prepare a polymerization initiator solution, which is used in suspension polymerization carried out at from 45 to 70°C.

COPYRIGHT: (C)1995,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel method for producing a fluorine-containing elastomer. More specifically, the present invention provides that the vulcanizate has excellent heat resistance, oil resistance, chemical resistance, etc., and has the same molecular weight as the fluorine-containing elastomer produced by the emulsion polymerization method which has been widely used in the past. Suspension polymerization of fluoroelastomers in an aqueous medium, which is a rubber-like elastic material with low Mooney viscosity, has small compression set, good mold releasability, and little mold stains. Thus, the present invention relates to a method that can be safely and efficiently produced without using a conventionally used CFC-based solvent that destroys the ozone layer, and that a monomer and a solvent can be easily recovered.

[0002]

2. Description of the Related Art Fluorine-containing elastomers having excellent heat resistance, oil resistance and chemical resistance are widely used in industry as containers, sealing materials and hoses used under severe conditions. Industrially useful fluorinated elastomers include
Binary system consisting of vinylidene fluoride (hereinafter referred to as VdF) unit and hexafluoropropylene (hereinafter referred to as HFP) unit, and ternary system composed of VdF unit, HFP unit and tetrafluoroethylene (hereinafter referred to as TFE) unit Fluorine-containing elastomers and the like can be mentioned.

As a method for producing such a fluorine-containing elastomer, an emulsion polymerization method, a suspension polymerization method and a solution polymerization method are known. In particular, the suspension polymerization method is a method in which a monomer or an organic solvent in which a monomer is dissolved is dispersed in water with a suspension stabilizer, and polymerization is performed using an oil-soluble organic peroxide. Since it is possible to obtain a fluorine-containing elastomer having excellent properties and mechanical properties, it is an industrially preferable method (US Pat. No. 3,801,552, US Pat. No. 4,985,520).

However, the suspension polymerization method uses a halogenated hydrocarbon such as trichlorotrifluoroethane as a polymerization medium, and since it has a high affinity with a fluorine-containing elastomer or a monomer, it is contained in polymer particles. It is difficult to dissolve, for example, trichlorotrifluoroethane and the monomer after the polymerization by dissolving with the raw material monomer. In addition, halogenated hydrocarbons such as chlorofluorocarbons are regarded as one of the substances that cause the destruction of the ozone layer, and the use thereof is being abolished internationally.

Further, in order to obtain a fluorine-containing elastomer having a high molecular weight, fluorocarbon R-113 (CCl ₂ FCClF ₂ ), R-141b (C
Halogenated hydrocarbons such as H ₃ CFCl ₂ ) are most suitable, while hydrocarbon solvents generally have high chain transfer reactivity. Therefore, it has never been considered to obtain a high molecular weight fluorine-containing elastomer using the latter.

A method has also been proposed in which suspension polymerization is carried out by adding only an oil-soluble organic peroxide without using any halogenated hydrocarbon (JP-A-3-207701, JP-A-3-207701). No. 247608). However,
This method is not practical because the oil-soluble organic peroxide is not diluted with a diluent and therefore has a problem in safety during handling such as transportation.

[0007]

Under these circumstances, the object of the present invention is to overcome the drawbacks of the conventional method for producing a fluorine-containing elastomer by the suspension polymerization method, and to make the vulcanized product heat-resistant. It is a rubber-like elastic material that has excellent properties, oil resistance, chemical resistance, etc., and has the same molecular weight and low Mooney viscosity as compared to the fluorine-containing elastomers that have been widely used in the past and have a low compression set. Fluorine-containing elastomer, which has features such as good mold releasability and little stain on the mold, is treated with a fluorocarbon elastomer that is conventionally used to destroy the ozone layer by suspension polymerization in an aqueous medium. It can be manufactured safely and efficiently without using it at all.
It is an object of the present invention to provide a method capable of easily recovering a monomer or a solvent.

[0008]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that a fluorine-containing elastomer comprising a vinylidene fluoride unit and a fluorine-containing monomer copolymerizable therewith is suspended. When the turbid polymerization method is used, an oil-soluble organic peroxide diluted with a specific water-soluble hydrocarbon solvent containing no halogen atom is used, and the polymerization temperature is 45 to
It was found that the object can be achieved by suspension polymerization at 70 ° C., and the present invention has been completed based on this finding.

That is, according to the present invention, when a fluoroelastomer comprising a vinylidene fluoride unit and at least one other fluorine-containing monomer unit copolymerizable therewith is produced by a suspension polymerization method, (1) an aqueous medium The above monomer is dispersed in an aqueous medium containing 0.001 to 3 parts by weight of a suspension stabilizer with respect to 100 parts by weight, and (2) 0.001 to 5 parts by weight based on 100 parts by weight of the aqueous medium. Part of the oil-soluble organic peroxide is represented by the general formula R ₁ —OH, R ₂ —COO—R ₁ or R ₁ —CO—R ₃ (wherein R ₁ and R ₃ are a methyl group or a tert-butyl group, R ₂ is a hydrogen atom, a methyl group or a tert-butyl group) is a water-soluble hydrocarbon solvent not containing a halogen atom, and a polymerization initiator solution diluted to a concentration of 0.1 to 75% by weight is used. (3) Suspension polymerization 45-70 The method of producing a fluorine-containing elastomer, which comprises carrying out at a temperature, and optionally, the general formula R · I n _(R in the formula, the hydrocarbon group having 1 to 3 carbon atoms, or 6 of carbon atoms of, An iodine compound represented by a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group, n is 1 or 2) in an amount of 0.005 to 5 parts by weight based on 100 parts by weight of the aqueous medium; It is intended to provide the above method performed by dispersing in a medium.

The fluorine-containing monomer copolymerizable with VdF used in the present invention includes, for example, HFP, TFE, perfluoroalkyl perfluorovinyl ether (hereinafter abbreviated as PFAVE), and the like.
Examples of E include perfluoromethyl perfluorovinyl ether, perfluoroethyl perfluorovinyl ether, and perfluoropropyl perfluorovinyl ether.

V obtained in the most useful embodiment of the present invention
In a binary fluorine-containing elastomer composed of dF units and HFP units, and a ternary fluorine-containing elastomer composed of VdF units, HFP units and TFE units, VdF
The content ratio of the unit to the HFP unit is usually 40: 6 by weight.
It is within the range of 0 to 80:20, and the preferable content ratio is 5 in the binary fluorine-containing elastomer.
It is in the range of 5:45 to 75:25, and in the ternary fluorine-containing elastomer, the weight ratio is 45:55 to 7.
The range is 0:30. The ternary fluorine-containing elastomer has a TFE unit content of 1 to 35% by weight, preferably 5 to 25% by weight.

Further, as the fluorine-containing elastomer containing PFAVE, for example, the VdF unit content is 10 to 85 mol%, the TFE unit content is 3 to 80 mol%, and PFAVE.
Those having a unit content of 2 to 50 mol% are preferable.

Fluorine-containing elastomers containing monomer units in such a proportion show rubber-like elasticity effective as an elastomer, while those in which the proportion of each monomer unit deviates from the above range are regarded as resins. It has properties and is not preferable for the purpose of the present invention.

In the method of the present invention, (1) aqueous medium 1
In an aqueous medium with respect to 00 parts by weight containing a suspension stabilizer 0.001 parts by weight, the monomer mixture having a predetermined composition (initial charge monomer), and optionally, the general formula (I) R · _{I n} The iodine compound represented by formula (I) (R and n in the formula have the same meanings as described above) was added to an aqueous medium of 100 parts by weight.
(3) Aqueous medium 10 while mechanically stirring and dispersing in a proportion of 005 to 5 parts by weight and (2) maintaining the liquid temperature at about 45 to 70 ° C, preferably 50 to 60 ° C.
0.001 to 5 parts by weight of an oil-soluble organic peroxide based on 0 part by weight of the general formula R ₁ —OH, R ₂ —COO—R ₁ or R ₁ —CO—R ₃ (R _{1 in the} formula , R ₂ and R ₃ have the same meanings as described above), and suspended by using a polymerization initiator solution diluted to a concentration of 0.1 to 75% by weight with a halogen atom-free water-soluble hydrocarbon solvent. Polymerize.

The polymerization temperature is set in the range of 45 to 70 ° C. When the temperature is lower than 45 ° C., the polymerization rate is slow, and when the temperature exceeds 70 ° C., suspended particles of the polymer become sticky during the polymerization, and blocking is likely to occur. This is because the suspended state cannot be maintained.

In the polymerization reaction of the present invention, the polymerization pressure is 5 to 50 kg / cm ² · G, especially 8 to 30 kg /
The range of cm ² · G is preferable. In this case, the polymerization pressure is set by adjusting the amount of the initial charged monomer, and after the initiation of the polymerization, a mixed monomer (additional monomer) having a new composition is added so that the polymerization pressure becomes constant and the polymerization proceeds. The preferred polymerization pressure is within this range: 5 kg / cm ² · G
On reaction rate the monomer concentration in the polymerization system too low slow is less than the molecular weight does not increase sufficiently, 50 kg / cm ²
This is because if it exceeds G, the amount of liquefied monomer increases too much, resulting in simply increasing the amount of unreacted monomer, which leads to a decrease in production efficiency.

The amount of the polymer produced is almost equal to the amount of the additional monomer, and is preferably in the range of 10 to 300 parts by weight, especially 20 to 250 parts by weight, based on 100 parts by weight of the aqueous medium. The preferred amount of polymer produced is in this range.
This is because if it is less than 10 parts by weight, the productivity is remarkably low, and if it exceeds 300 parts by weight, the solid content concentration is too high and stirring becomes difficult.

The oil-soluble organic peroxide used in the present invention is, for example, diisopropyl peroxydicarbonate (hereinafter abbreviated as IPP), di-sec-butyl peroxydicarbonate, di-sec-hexyl peroxydicarbonate. , Di-n-propylperoxydicarbonate, di-n-butylperoxydicarbonate and other dialkylperoxydicarbonates, tert-butylperoxyisobutyrate, tert-butylperoxypivalate and other peroxyesters Diacyl peroxides such as dipropionyl peroxide,
Di [perfluoro (or chlorofluoro) acyl] such as di (perfluoropropionyl) peroxide, di (trichlorooctafluorohexanoyl) peroxide
Dialkyl peroxydicarbonate is preferably selected from peroxides and the like, and IPP is particularly preferable. These oil-soluble organic peroxides may be used alone or in combination of two or more, and the amount thereof used is usually 0.001 to 5 parts by weight, preferably 100 parts by weight of the aqueous medium. It is selected in the range of 0.01 to 3 parts by weight.

Since the oil-soluble organic peroxide has a risk of explosion due to heat and impact, it cannot be transported unless it is diluted with some kind of solvent. Conventionally, in the suspension polymerization method of a fluorine-containing elastomer, an oil-soluble organic peroxide diluted with a halogenated hydrocarbon solvent is used, and when a solvent diluted with a hydrocarbon solvent is used, a solvent is generated by radicals during the polymerization reaction. It has been considered that the reaction of extracting hydrogen atoms from the compound occurs, so that the molecular weight is difficult to increase and the polymerization rate is slow, which is not practical.

However, the general formula R ₁ --OH, R ₂ --COO--R ₁ or R ₁ --CO--R ₃ used in the present invention (wherein R ₁ , R ₂ and R ₃ are the same as above) When diluting an oil-soluble organic peroxide with a water-soluble hydrocarbon solvent that does not contain a halogen atom, the fluorine-containing elastomer having a low to high molecular weight can be safely and efficiently produced, and a monomer And solvent can be easily collected.
The hydrocarbon solvent of the present invention is less likely to adversely affect polymerization because the hydrocarbon solvent has a relatively small chain transfer reactivity,
Moreover, since it is water-soluble, it dissolves in an aqueous medium, and it is presumed that an extremely small amount is contained in the oil droplets composed of the raw material monomer and the oil-soluble organic peroxide, which serve as a polymerization site. further,
Since most of the solvent is dissolved in the aqueous medium, the solvent or the solvent containing the raw material monomer hardly penetrates into the produced polymer, and the solvent and the raw material monomer are easily recovered.

The water-soluble hydrocarbon solvent containing no halogen atom used in the present invention is specifically methanol, tert-butyl alcohol, methyl formate, formic acid-
tert-butyl, methyl acetate, acetic acid-tert-butyl, methyl pivalate, pivalic acid-tert-butyl, acetone, methyl-tert-butyl ketone, di-
It is tert-butyl ketone. More preferred solvents are methanol, tert-butyl alcohol, methyl acetate,
It is -tert-butyl acetate, and methyl acetate and -tert-butyl acetate are particularly preferable. These solvents may be used alone or in combination of two or more.

These solvents are oil-soluble organic peroxides,
It is used so as to be diluted to 0.1 to 75% by weight, preferably 1 to 60% by weight. If this concentration exceeds 75% by weight, the concentration of the organic peroxide is too high, which may cause a problem in transport safety, and if it is less than 0.1% by weight, the concentration is too low and the amount of solvent increases. It is not preferable because the recovery amount increases.

[0023] In the present invention, particularly when producing a peroxide vulcanizable fluoroelastomer, in the molecule of the fluorine-containing elastomer, for introducing bonded iodine atom as a crosslinking point, the general formula R · I _n ( I) (R and n in the formula have the same meanings as described above), preferably the general formula R ′ · I _m (wherein R ′ is a hydrocarbon group having 1 to 3 carbon atoms, m is 1 or 2). There is used an iodine compound represented by

In this general formula (I), R has 3 carbon atoms.
The following hydrocarbon group, or a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 6 or less carbon atoms, and n is required to be 1 or 2. The reason that n, which is a bond of R, is set to 1 or 2 is that when n is 3, the resulting fluorine-containing elastomer has a three-dimensional structure and is inferior in workability. Such iodine compounds are selected from those that do not decompose or lose their effects under the polymerization conditions, such as monoiodomethane, diiodomethane, 1-iodoethane, 1,2-diiodoethane, 1-iodo-n-propane. , Isopropyl iodide, 1,3-diiodo-n-propane, 2-iodoperfluoropropane, 1,4-diiodoperfluoro-n
-Butane, 1,6-diiodoperfluoro-n-hexane, 1,5-diiodo-2,4-dichloroperfluoro-n-pentane and the like can be mentioned. Among these, diiodomethane is the most preferable in terms of polymerization reactivity, vulcanization reactivity, and easy availability. These iodine compounds may be used alone or in combination of two or more.

When VdF and a fluorine-containing olefin copolymerizable with VdF are copolymerized in the presence of the iodine compound represented by the general formula (I), the carbon-iodine bond in the iodine compound reacts with radicals. Since it is active, it is considered that normal telomerization reaction proceeds to introduce iodine at the polymer terminal. This iodine compound is used in a proportion of 0.005 to 5 parts by weight, preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the aqueous medium.

Examples of the suspension stabilizer used in the present invention include methyl cellulose, carboxymethyl cellulose, bentonite, talc, diatomaceous earth, and the like, and methyl cellulose is preferable. These suspension stabilizers may be used alone or in combination of two or more, and the amount thereof is usually 0.001 to 3 parts by weight, preferably 100 parts by weight of the aqueous medium. 0.01 ~
It is selected in the range of 1 part by weight.

The polymerization time in the present invention is about 3 to 50 hours, which is the same as in the production of ordinary fluorine-containing elastomers. The amount of the fluorinated elastomer produced is made substantially equal to the amount of the added monomer, and the composition of the added monomer is made substantially the same as the composition of the fluorinated elastomer.

The initial charged monomer composition and the additional monomer composition are measured by gas chromatography, and the composition of the monomer unit in the fluorine-containing elastomer is determined by dissolving the elastomer in acetone and measuring it by ¹⁹ F-NMR.

The fluorinated elastomer obtained by the present invention is usually used after being vulcanized and molded.

Next, the method of vulcanizing the fluorine-containing elastomer will be described. As the vulcanization method, a vulcanization method using a polyol compound and a polyamine compound can be used.
In particular, vulcanization with a polyol compound is advantageous because the compression set resistance can be further improved. Also,
Fluorine-containing elastomers manufactured using iodine compounds can be vulcanized with polyol compounds, polyamine compounds, etc., but in particular peroxide vulcanization with organic peroxides is possible and durability against chemicals such as acids and alkalis is possible. Is significantly improved.

An example of a vulcanization method using a polyol compound will be described. The fluorine-containing elastomer of the present invention,
(A) a polyhydroxy aromatic compound, (b) a vulcanization accelerator, (c) a divalent metal hydroxide and / or a divalent metal oxide, and, if necessary, other compounding agents on a roll or After kneading with a Banbury mixer, the mixture is put into a mold and pressurized to perform primary vulcanization (press vulcanization), and then secondary vulcanization. Generally, the primary vulcanization conditions are a temperature of 100 to 200 ° C. and a vulcanization time of 10 to 1.
The pressure is selected from the range of 80 minutes and the pressure of 20 to 100 kg / cm ² , and the secondary vulcanization conditions are selected from the range of a temperature of 150 to 300 ° C. and a vulcanization time of 0 to 30 hours. Further, in some cases, the secondary vulcanization can be omitted.

Examples of the polyhydroxy aromatic compound as the component (a) include bisphenol AF, bisphenol A, bisphenol S, dihydroxybenzophenone,
Examples thereof include hydroquinone, 4,4'-thiodiphenol and metal salts thereof, and bisphenol AF is particularly preferable. The blending ratio is usually 0.1 to 10 parts by weight, preferably 0.6 to 5 parts by weight, based on 100 parts by weight of the fluoroelastomer. The mixing ratio of the component (a) is set in this range because a vulcanized molded product cannot be obtained when the amount is less than 0.1 parts by weight, and the elastomer elasticity is lost when the amount exceeds 10 parts by weight. These polyhydroxy aromatic compounds may be used alone or in combination of two or more.

As the vulcanization accelerator of the component (b), a phosphonium salt, an ammonium salt, an iminium salt, a sulfonium salt, an aminophosphine derivative or the like is used. , Tetrabutylammonium fluoride, tetrabutylammonium bromide, 8-benzyl-1,8-diazabicyclo [5.4.0] -undecenonium chloride, bis (benzyldiphenylphosphine) iminium chloride and the like, especially benzyl Triphenylphosphonium chloride, 8-benzyl-1,8-diazabicyclo [5.4.0] -undecenonium chloride and bis (benzyldiphenylphosphine) iminium chloride are preferred. The blending ratio is usually 0.05 to 2 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of the fluoroelastomer. The blending ratio of the component (b) is set in this range because the vulcanization rate becomes extremely slow when it is less than 0.05 parts by weight, and the compression set resistance is significantly deteriorated when it exceeds 2 parts by weight. is there. Further, these vulcanization accelerators may be used alone or in combination of two or more.

Examples of the divalent metal hydroxide and / or the divalent metal oxide as the component (c) include oxides and hydroxides of magnesium, calcium, zinc, lead and the like, and particularly magnesium and Calcium oxides and hydroxides are preferred. Fluorine-containing elastomer 1
The amount is usually 1 to 30 parts by weight, preferably 2 to 20 parts by weight, based on 00 parts by weight. The mixing ratio of the component (c) is set in this range because vulcanization does not proceed sufficiently when it is less than 1 part by weight, and compression set resistance is deteriorated when it exceeds 30 parts by weight. In addition, one of these may be used, or 2
You may use it in combination of 2 or more types.

In the present invention, further, if necessary,
Other suitable additives such as carbon black, austin black, graphite, silica, clay, diatomaceous earth, talc, wollastonite, calcium carbonate, calcium silicate, calcium fluoride, fillers such as barium sulfate, sulfone compounds, Phosphoric acid ester, fatty amine, higher fatty acid ester, fatty acid calcium, fatty acid amide, low molecular weight polyethylene, silicone oil, silicone grease, stearic acid, sodium stearate, calcium stearate, magnesium stearate, aluminum stearate, zinc stearate, etc. A processing aid, a coloring agent such as titanium white, red iron oxide, and the like can be added.

The compounding ratio of the filler is preferably in the range of 0.1 to 100 parts by weight, and particularly preferably in the range of 1 to 60 parts by weight, based on 100 parts by weight of the fluoroelastomer. The reason for setting the blending ratio of the filler to this range is that if it is less than 0.1 part by weight, the compounding effect is ineffective, and if it exceeds 100 parts by weight, the elastomer elasticity is lost. The mixing ratio of the processing aid is usually 10 parts by weight or less, and particularly preferably 5 parts by weight or less, relative to 100 parts by weight of the fluorine-containing elastomer. If the blending ratio of the processing aid exceeds this range, the heat resistance is adversely affected. The mixing ratio of the colorant is preferably 50 parts by weight or less, and particularly preferably 3 parts by weight, based on 100 parts by weight of the fluoroelastomer.
It is 0 parts by weight or less. The mixing ratio of the colorant is set in this range because the compression set resistance is deteriorated when it exceeds 50 parts by weight.

Vulcanization with a polyamine compound is carried out, for example, by
It is preferably used in applications such as diaphragms that require elongation rather than compression set resistance. As the vulcanization conditions, the conditions in the case of the vulcanization method using the above-mentioned polyol compound can be applied as they are.

When polyamine vulcanization is performed, (d) a polyamine compound such as hexamethylenediamine, hexamethylenediamine carbamate, ethylenediamine is used in place of the above-mentioned (a) polyhydroxy aromatic compound and (b) vulcanization accelerator. Carbamate, N, N-dicinnamylidene-1,6-hexamethylenediamine, 4,4 '
-Bis (aminocyclohexyl) methane carbamate and the like are preferably used. The mixing ratio is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the fluoroelastomer. The mixing ratio of the component (d) is set in this range because a vulcanized molded product cannot be obtained when the amount is less than 0.1 part by weight, and the elastomer elasticity is lost when the amount exceeds 10 parts by weight. These polyamine compounds may be used alone or in combination of two or more.

Next, an example of the peroxide vulcanization method will be described. The fluorine-containing elastomer of the present invention contains (e) an organic peroxide, (f) a polyfunctional unsaturated compound, and optionally (c) a divalent metal hydroxide and / or a divalent metal. After kneading the oxide and the above-mentioned other additive components with a roll or a Banbury mixer, the mixture is put into a mold and pressurized to perform primary vulcanization (press vulcanization), and then secondary vulcanization. Generally, the conditions for primary vulcanization are a temperature of 100 to 200 ° C. and a vulcanization time of 5 to 30.
Min, pressure selected from the range of 20 to 300 kg / cm ² ,
The conditions for the secondary vulcanization are selected from the range of usually a temperature of 100 to 200 ° C. and a vulcanization time of 0 to 30 hours. Further, in some cases, the secondary vulcanization can be omitted.

As the organic peroxide as the component (e), those which generate peroxy radicals under vulcanization conditions are used, and for example, 1,1-bis (tert-butylperoxy) -3,5,5. -Trimethylcyclohexane, 1,1
-Bis (tert-butylperoxy) cyclohexane, 2,2-bis (tert-butylperoxy) octane, n-butyl-4,4-bis (tert-butylperoxy) valerate, 2,2-bis (tert) -Butylperoxy) butane, 2,5-dimethylhexane-
2,5-dihydroxy peroxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, dicumyl peroxide, α, α'-bis (tert
-Butylperoxy-m-isopropyl) benzene,
2,5-Dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t
ert-butylperoxy) hexyne-3, benzoyl peroxide, tert-butylperoxybenzene,
2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxymaleic acid, tert-butylperoxyisopropyl carbonate and the like are mentioned, and particularly preferred component (e) is 2,5
-Dimethyl-2,5-di (tert-butylperoxy) hexane, dicumyl peroxide, α, α'-bis (tert-butylperoxy-m-isopropyl) benzene. The mixing ratio is usually 0.05 to 5 parts by weight, and the preferable range is 0.1 to 3 parts by weight, relative to 100 parts by weight of the fluorine-containing elastomer. The mixing ratio of the component (e) is set to this range because if it is less than 0.05 parts by weight, a sufficient vulcanization rate cannot be obtained and the mold releasability is deteriorated, and if it exceeds 5 parts by weight, the compression resistance is high. This is because the distortion property is significantly deteriorated. Further, the organic peroxide may be used alone or in combination of two or more.

Examples of the polyfunctional unsaturated compound as the component (f) include triallyl cyanurate, trimethallyl isocyanurate, triallyl isocyanurate, triacryl formal, triallyl trimellitate, N,
N'-m-phenylene bismaleimide, diallyl phthalate, tetraallyl terephthalamide, tris (diallylamine) -s-triazine, triallyl phosphite,
Examples thereof include N, N-diallyl acrylamide, and particularly preferred is triallyl isocyanurate. The mixing ratio is usually 0.1 to 10 parts by weight, and the preferable range is 0.2 to 6 parts by weight, relative to 100 parts by weight of the fluorine-containing elastomer. The blending ratio of the component (f) is set to this range because if it is less than 0.1 part by weight, a sufficient crosslinking density cannot be obtained, and if it exceeds 10 parts by weight, the component (f) bleeds to the elastomer surface during molding, This is because it causes molding failure. Further, the polyfunctional unsaturated compound may be used alone or in combination of two or more kinds.

[0042]

EFFECTS OF THE INVENTION According to the method of the present invention, (1) a polymerization reaction can be safely and efficiently carried out without using a CFC-type solvent that destroys the ozone layer as a solvent. (2) Chain transfer to fluoroolefins Fluorine-containing elastomer that has excellent heat resistance, oil resistance, chemical resistance, etc. as it uses a solvent with low resistance, has a small compression set, has good mold releasability, and has little mold fouling. And (3) the unreacted monomer and the solvent can be easily recovered.

The fluorine-containing elastomer obtained by the method of the present invention has a small mill shrinkage during roll molding. further,
The vulcanized product of this fluorine-containing elastomer has a low 100% tensile stress, a low hardness and elongation, and a small compression set, and is therefore used as an elastic body in various fields.

For example, heat fixing roll, control valve, diaphragm, or O-ring, V-packing, U-packing, Y-packing, D-ring, trigonal ring, T-ring
Molded packing such as rings and X-rings, as well as gaskets, rubber valve seats, butterfly valves, stem valves,
Oil seal, SF-resistant engine oil molding, S-resistant
It can be used in the fields of G-grade engine oil moldings, fuel hoses, filler hoses, in-tank hoses, heat-shrinkable tubes, wet friction materials, wire coatings, piezoelectric materials, bellows-like joints for smoke exhaust ducts, and the like.

[0045]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The physical properties of the fluorinated elastomer were determined by the methods described below.

(1) Intrinsic viscosity [η]: 0.1 g / 100 by dissolving the fluorine-containing elastomer in methyl ethyl ketone
The concentration was set to ml and the measurement was performed at 35 ° C. using a capillary viscometer.

(2) Measurement of molecular weight distribution: Mn under the following conditions:
Mw was measured. Liquid chromatograph: HLC-8020 [manufactured by Tosoh Corporation] Column: KF-80M (2) +
KF-800P (pre-column) [Showa Denko KK] Integrator: AS-8010 [Tosoh KK] Developing solvent: Tetrahydrofuran concentration 0.1% by weight Temperature: 35 ° C Standard polymer for molecular weight calibration curve: Monodisperse polystyrene Various [manufactured by Tosoh Corporation] [Mw / Mn to 1.2 (ma
x)]

(3) Mooney viscosity: JIS-K6300
According to the above, an L-type rotor was used, the temperature was 121 ° C., the preheating time was 1 minute, and the operation time of the rotor was 10 minutes, using a VR-103ST manufactured by Ueshima Seisakusho.

(4) Hardness of vulcanized product: Determined according to JIS-A. (5) 100% tensile stress of vulcanized product: JIS-K6301
It was calculated according to. (6) Tensile strength of vulcanized product: Determined according to JIS-K6301. (7) Elongation of vulcanized product: determined according to JIS-K6301.

(8) Compression set of vulcanized product: JIS-B2
Using the P-24 of the O-ring for exercise specified in 401, the temperature is 200 ° C and the condition is 72 hours.
It measured according to 01.

Example 1 An autoclave having an internal volume of 15 liter equipped with an electromagnetic induction stirrer was sufficiently replaced with nitrogen gas, and depressurization and nitrogen filling were repeated 3 times to replace nitrogen, then depressurized and deoxidized. A solution prepared by dissolving 3.6 g of methyl cellulose (viscosity 50 cp) as a suspension stabilizer in 4760 g of pure water was charged, and the temperature was kept at 50 ° C. while stirring at 600 rpm. Then VdF 29.5% by weight, HFP 64.
Using a mixed monomer composed of 5% by weight and 6.0% by weight of TFE as an initial charging monomer, the pressure was 26.5 kg / c.
It was prepared until it reached m ² · G. Next, a polymerization initiator solution prepared by dissolving 4.3 g of IPP, which is an oil-soluble organic peroxide, in 50.6 g of methyl acetate was injected under pressure to initiate polymerization. When the polymerization reaction progressed and the pressure dropped to 25.5 kg / cm ² · G, VdF 52.7% by weight, HFP 25.5
Wt% and TFE 21.8 wt% mixed monomer is additionally added as an additional monomer, and the pressure is again 26.5 kg.
/ Cm ² · G. Such an operation was repeated to carry out a polymerization reaction for 6 hours. After the completion of the polymerization reaction, the residual mixed monomer was evacuated, the obtained suspension was dehydrated by a centrifuge, the solid content was sufficiently washed with water, and then vacuum dried at 100 ° C. to obtain about 6 kg of an elastomer. . When the monomer composition ratio of the obtained fluorine-containing elastomer was analyzed by ¹⁹ F-NMR, it was found that the VdF unit was 54.6% by weight, the HFP unit was 25.1% by weight and the TFE unit was 20.3% by weight. The [η] of this fluorine-containing elastomer is 258.
ml / g, Mooney viscosity ML _{1 + 10} (121 ° C) is 120
Met. The elastomer properties are shown in Table 1.

100 parts by weight of the fluorine-containing elastomer was wound around an open-type kneading roll, and a medium thermal (“MT”) carbon “THERMAX N-9” manufactured by CANCARB was manufactured.
90 "20 parts by weight, Omi Chemical Co., Ltd. calcium hydroxide" Carbit "6 parts by weight, Kyowa Chemical Industry Co., Ltd. high activity magnesium oxide" Kyowamag 150 "3 parts by weight, bisphenol AF 2 parts by weight, bis ( Benzyldiphenylphosphine) iminium chloride (0.3 parts by weight) was kneaded and allowed to stand overnight for aging. Then, after re-kneading, it was put into a mold and press-vulcanized at a temperature of 177 ° C. for 30 minutes to form a sheet having a thickness of 2 mm and an O-ring. Then remove from the mold, temperature 232
Secondary vulcanization was completed by heating for 24 hours in an air circulation type furnace at ℃, and various tests were conducted. The properties of the vulcanizate are shown in Table 1.

Comparative Example 1 Auto with an internal volume of 15 liters equipped with an electromagnetic induction stirrer
Thoroughly replace the clave with nitrogen gas and reduce the pressure and fill with nitrogen.
After nitrogen replacement was repeated 3 times, depressurized and deoxidized.
Methyl cellulose (viscosity 50c
p) A solution in which 4.64 g was dissolved was charged, and 600 rp
The temperature was maintained at 50 ° C. with stirring. Then Vd
F 28.9% by weight, HFP 65.2% by weight and TF
A mixed monomer consisting of E 5.9% by weight was initially charged.
Pressure of 20kg / cm^Two・ Complete until G
Complicated. Next, IPP of oil-soluble organic peroxide 8.6 g
Freon R-141b (CH₃CFCl_Two) 85.4 g
The polymerization initiator solution dissolved in
It was Polymerization reaction progresses and pressure is 19.5 kg / cm ^Two・
When it reaches G, VdF 52.7% by weight, HFP
A mixture consisting of 25.5% by weight and TFE 21.8% by weight.
The combined monomer is added as an additional monomer, and the pressure is adjusted to 2 again.
0 kg / cm^Two・ Returned to G. Repeat this operation
Then, the polymerization reaction was carried out for 5 hours. Remains after completion of polymerization reaction
Evacuate the mixed monomers and centrifuge the resulting suspension.
After dehydration and washing the solids thoroughly with water, vacuum at 100 ° C.
After drying, about 4.5 kg of elastomer was obtained. Got
The monomer composition ratio of the fluorine-containing elastomer¹⁹F-NMR
Analysis by VdF unit 52.6% by weight, H
26.5% by weight of FP unit and 20.9% by weight of TFE unit
Met. [Η] of this fluorine-containing elastomer is 257
ml / g, Mooney viscosity ML_{1 + 10}(121 ℃) is 120
Met. The elastomer properties are shown in Table 1. The fluorine-containing
The elastomer was vulcanized in the same manner as in Example 1, and various
The test was conducted. The results are shown in Table 1. As a result Example
With the same elastomeric properties and vulcanizate properties as 1
Although obtained, the solvent R-141b of the polymerization initiator used was
It is ozone-depleting and not good for the environment.

Example 2 An autoclave with an internal volume of 1 liter equipped with an electromagnetic induction stirrer was sufficiently replaced with nitrogen gas, and depressurization and nitrogen filling were repeated 3 times to replace nitrogen, and then depressurized state and then degassed. Methyl cellulose (viscosity 50c
p) Charge a solution in which 0.3 g was dissolved, and 600 rpm
The temperature was maintained at 50 ° C. with stirring. Then VdF
Using a mixed monomer composed of 29.9% by weight and 70.1% by weight of HFP as an initial charging monomer, the pressure was 13 k.
It was charged until it reached g / cm ² · G. Next, IPP
A polymerization initiator solution prepared by dissolving 1.8 g of methyl acetate in 4.0 g of the mixture was press-fitted to initiate polymerization. When the polymerization reaction progresses and the pressure drops to 12 kg / cm ² · G, VdF
A mixed monomer composed of 63.1% by weight and 36.9% by weight of HFP was added as an additional monomer, and the pressure was adjusted to 13 again.
It was returned to kg / cm ² · G. The above operation was repeated to carry out the polymerization reaction for about 13 hours. After the completion of the polymerization reaction, the residual mixed monomer was evacuated, the obtained suspension was filtered, the solid content was sufficiently washed with water, and then vacuum dried at 100 ° C. to obtain about 300 g of an elastomer. When the monomer composition ratio of the obtained fluorine-containing elastomer was analyzed by ¹⁹ F-NMR, VdF unit was 65.3% by weight and HFP was
The unit is 34.7% by weight, and the [η] is 90 ml / g.
Met.

Example 3 The procedure of Example 2 was repeated, except that 3.7 g of tert-butyl acetate was used instead of 4.0 g of methyl acetate, and the polymerization time was changed to about 14 hours. The yield of the obtained fluorine-containing elastomer was about 340 g, the monomer composition ratio was 63.2% by weight of VdF unit and 36.8% by weight of HFP unit,
The [η] was 92 ml / g.

Comparative Example 2 Perchlorethylene 5.7 was used in place of 4.0 g of methyl acetate.
It carried out like Example 2 except having used g. The yield of the obtained fluorine-containing elastomer was about 3 g, the monomer composition ratio was VdF unit 63.5% by weight and HFP unit 36.5% by weight, and [η] thereof was 10 ml / g. The yield was extremely small compared to Examples 2 and 3, and the viscosity [η]
Was also extremely low.

Comparative Example 3 The procedure of Comparative Example 1 was repeated under the conditions shown in Table 2. The properties of the obtained elastomer are shown in Table 2. Freon R-225cb used as a solvent has ozone depleting properties and is not good for the environment.

Example 4 Auto with an internal volume of 15 liters equipped with an electromagnetic induction stirrer
Thoroughly replace the clave with nitrogen gas and reduce the pressure and fill with nitrogen.
After nitrogen replacement was repeated 3 times, depressurized and deoxidized.
Methyl cellulose (viscosity 50c
p) Charge a solution in which 4.1 g was dissolved, and 600 rpm
The temperature was maintained at 50 ° C. with stirring. Then VdF
 15.6% by weight, HFP 78.2% by weight and TFE
 Initially charged with a mixed monomer consisting of 6.2 wt%
As a maker, the pressure is 24 kg / cm ^Two・ Prepare until G
I see. Next, press in 27.7 g of diiodomethane, and
Dissolve 4.3 g of IPP in 50.6 g of methyl acetate
The polymerization initiator solution was injected under pressure to initiate the polymerization. Polymerization
The response progresses and the pressure is 23 kg / cm.^Two・ Decreased to G
, VdF 47.7% by weight, HFP 31.4% by weight
And a mixed monomer consisting of 20.9% by weight of TFE.
It is added as an additional monomer, and the pressure is again 24 kg / cm.^Two
・ Returned to G. Repeat this operation at 14.5 o'clock
A polymerization reaction was carried out. After the polymerization reaction is complete, the remaining mixed
Evacuate the Nomer and dehydrate the resulting suspension in a centrifuge.
After washing the solid content with water, vacuum drying at 100 ° C
About 5 kg of elastomer was obtained. The above polymerization conditions and
And elastomer yields are shown in Table 3. The obtained fluorine-containing
The monomer composition ratio of the last¹⁹Analyzed by F-NMR
Then, VdF unit 46.3% by weight, HFP unit 3
2.5% by weight and TFE unit 21.2% by weight.
This fluorine-containing elastomer has an [η] of 50 ml / g,
-Knee viscosity ML_{1 + 10}(121 ° C) was 7. Eras
Tomer properties are shown in Table 1.

100 parts by weight of the fluorine-containing elastomer was wrapped around an open type kneading roll, and a medium thermal (“MT”) carbon “Thermax N-9” manufactured by CANCARB was manufactured.
20 parts by weight of 90 "and 3 parts by weight of highly active magnesium oxide" Kyowamag 150 "manufactured by Kyowa Chemical Industry Co., Ltd. were kneaded. Next, 4 parts by weight of triallyl isocyanurate "TAIC" manufactured by Nippon Kasei Co., Ltd., 2,5-
Dimethyl-2,5-di (tert-butylperoxy)
3.75 parts by weight of hexane "Perhexa 25B-40 (peroxide content is 40% by weight)" was kneaded and allowed to stand overnight for aging. Then, after re-kneading, it was put into a mold and press-vulcanized at a temperature of 160 ° C. for 10 minutes to form a sheet and an O-ring having a thickness of 2 mm. Then, it was taken out from the mold and heated in an air circulation type furnace at a temperature of 180 ° C. for 4 hours to complete the secondary vulcanization, and various tests were conducted. The properties of the vulcanizate are shown in Table 1.

Comparative Example 4 As shown in Table 3, the solvent of the polymerization initiator was methyl acetate 5
R-113 (CCl ₂ FCClF ₂ ) 8 instead of 0.6 g
Example 4 except 6 g and changing the polymerization time to 13 hours
The same procedure as above was performed to obtain about 5 kg of elastomer. Table 1 shows the elastomer properties of the obtained elastomer and the properties of the vulcanized product. As a result, the same elastomer properties and vulcanizate properties as in Example 4 were obtained, but the solvent had ozone depletion properties and was not environmentally friendly.

Example 5 An autoclave with an internal volume of 10 liters equipped with an electromagnetic induction stirrer was sufficiently replaced with nitrogen gas, and depressurization and nitrogen filling were repeated 3 times to replace nitrogen, then depressurized and deoxidized. Methyl cellulose (viscosity 50c
p) A solution in which 4.16 g was dissolved was charged, and 600 rp
The temperature was maintained at 50 ° C. with stirring. Then Vd
F 28.7% by weight, HFP 65.6% by weight and TF
A mixed monomer consisting of 5.7% by weight of E was charged as an initial charging monomer until the pressure reached 20 kg / cm ² · G. Next, 10.3 g of IPP was added to methyl acetate 37.
The polymerization initiator solution dissolved in 0 g was injected under pressure to initiate the polymerization. Polymerization reaction progresses and pressure is 19.5 kg / cm
When it decreases to ²・ G, VdF 52.8% by weight, HF
A mixed monomer composed of 25.4% by weight of P and 21.8% by weight of TFE was added as an additional monomer, and the pressure was returned to 20 kg / cm ² · G again. Such an operation was repeated to carry out a polymerization reaction for 4.5 hours. After the completion of the polymerization reaction, the residual mixed monomer was evacuated, the obtained suspension was dehydrated with a centrifuge, and the solid content was thoroughly washed with water.
It was vacuum dried at 00 ° C. to obtain about 2.5 kg of elastomer. The monomer composition ratio of the obtained fluoroelastomer
^When analyzed by ¹⁹ F-NMR, VdF unit 51.
7% by weight, HFP unit 28.0% by weight and TFE unit 2
It was 0.3% by weight. This fluorinated elastomer has an [η] of 120 ml / g and a number average molecular weight Mn of 11.1
It was × 10 ⁴ . The fluorine-containing elastomer was used in Example 1
A vulcanized product was obtained in the same manner as above and various tests were conducted. The properties of the elastomer are shown in Table 4, and the properties of the vulcanized product are shown in Table 5.

Examples 6 to 9 and Comparative Examples 5 to 10 The same procedure as in Example 5 was carried out except that IPP was diluted with the solvent shown in Table 4 instead of methyl acetate. The properties of the elastomer are shown in Table 4. Further, in Examples 6 to 9, the elastomer was made into a vulcanized product in the same manner as in Example 1 and various tests were conducted. The properties of the vulcanizate are shown in Table 5.

Comparative Example 11 The procedure of Example 5 was repeated except that no solvent was used.
The properties of the elastomer are shown in Table 4. Further, in the same manner as in Example 1, various tests were conducted using the fluorinated elastomer as a vulcanized product. The properties of the vulcanizate are shown in Table 5. The vulcanized product of Comparative Example 11 is comparable to the physical properties of the vulcanized products of Examples 5 to 9 and uses only a small amount of IPP on a bench scale. Therefore, it is possible to handle IPP that is not diluted with a solvent, but on an industrial level. There is a problem with transportation and it is not a practical method.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[0067]

[Table 4]

[0068]

[Table 5]

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kenzo Hashimura 6-4100 Asahi-cho, Nobeoka-shi, Miyazaki Prefecture Asahi Kasei Kogyo Co., Ltd. (72) Inventor Michio Kasahara 6-4100 Asahi-cho, Nobeoka-shi, Miyazaki Asahi Kasei Kogyo Co., Ltd. (72) Inventor Yukihiro Ikeda 6-4100 Asahi-cho, Nobeoka-shi, Miyazaki Prefecture Asahi Kasei Kogyo Co., Ltd.

Claims (28)

[Claims] 1. A process for producing a fluorine-containing elastomer comprising a vinylidene fluoride unit and at least one other fluorine-containing monomer unit copolymerizable therewith by a suspension polymerization method, wherein (1) 100 parts by weight of an aqueous medium is added. On the other hand, 0.001-
The above monomer is dispersed in an aqueous medium containing 3 parts by weight of a suspension stabilizer, and (2) 0.001 to 5 parts by weight of an oil-soluble organic peroxide is added to 100 parts by weight of the aqueous medium, formula _{R 1 -OH, R 2 -COO-} R 1 or _{R 1 -CO-R 3 (R} 1 and R ₃ in the formula is a methyl group or a tert- butyl group, R ₂ represents a hydrogen atom, a methyl group or a tert Is a butyl group) and a polymerization initiator solution diluted to a concentration of 0.1 to 75 wt% with a halogen atom-free water-soluble hydrocarbon solvent is used. A method for producing a fluorine-containing elastomer, which is performed at a temperature of ° C. 2. A compound represented by the general formula R · I _n (wherein R is a hydrocarbon group having 1 to 3 carbon atoms, or 6 carbon atoms).
The following saturated or unsaturated fluorohydrocarbon groups or chlorofluorohydrocarbon groups, n is 1 or 2)
The iodine compound represented by
The production method according to claim 1, which is carried out by dispersing in an aqueous medium at a ratio of 0.005 to 5 parts by weight with respect to parts by weight. 3. The fluorine-containing elastomer is based on the total weight of the monomer units (A), (B) and (C), respectively.
A total of 65 to 100% by weight of (A) vinylidene fluoride units and (B) hexafluoropropylene units and (C) tetrafluoroethylene units of 35 to 0% by weight, and (A) vinylidene fluoride units and (B) ) The weight ratio with the hexafluoropropylene unit is 40:60 to 80: 2.
The manufacturing method according to claim 1, which is in the range of 0. 4. The fluorine-containing elastomer is based on the total weight of the monomer units (A), (B) and (C), respectively.
A total of 65 to 100% by weight of (A) vinylidene fluoride units and (B) hexafluoropropylene units and (C) tetrafluoroethylene units of 35 to 0% by weight, and (A) vinylidene fluoride units and (B) ) The weight ratio with the hexafluoropropylene unit is 40:60 to 80: 2.
The manufacturing method according to claim 2, which is in the range of 0. 5. The fluoroelastomer comprises (A) a vinylidene fluoride unit of 10 to 85 mol%, (C) a tetrafluoroethylene unit of 3 to 80 mol%, and (D) a perfluoroalkyl perfluorovinyl ether unit of 2 to 50 mol%. The manufacturing method according to claim 1, wherein the manufacturing method comprises%. 6. The fluorine-containing elastomer comprises (A) vinylidene fluoride unit of 10 to 85 mol%, (C) tetrafluoroethylene unit of 3 to 80 mol%, and (D) of perfluoroalkyl perfluorovinyl ether unit of 2 to 50 mol. The manufacturing method according to claim 2, wherein the manufacturing method comprises%. 7. The production method according to claim 1, 3 or 5, wherein the oil-soluble organic peroxide is dialkyl peroxydicarbonate. 8. The method according to claim 7, wherein the dialkyl peroxydicarbonate is diisopropyl peroxydicarbonate. 9. The production method according to claim 2, 4 or 6, wherein the oil-soluble organic peroxide is dialkyl peroxydicarbonate. 10. The method according to claim 9, wherein the dialkyl peroxydicarbonate is diisopropyl peroxydicarbonate. 11. The water-soluble hydrocarbon solvent is a compound represented by the general formula R ₁ —OH (wherein R ₁ is a methyl group or a tert-butyl group).
The manufacturing method described. 12. The water-soluble hydrocarbon solvent is a compound represented by the general formula R ₁ —OH (wherein R ₁ is a methyl group or a tert-butyl group).
The manufacturing method described. 13. The method according to claim 1 or 2, wherein the water-soluble hydrocarbon solvent is methyl alcohol. 14. The method according to claim 1 or 2, wherein the water-soluble hydrocarbon solvent is tert-butyl alcohol. 15. The water-soluble hydrocarbon solvent is represented by the general formula R ₂ —COO—R ₁ (wherein R ₁ is a methyl group or a tert-butyl group, R ₂ is a hydrogen atom, a methyl group or a tert-butyl group). The production method according to claim 1, 3, 5 or 7, which is a compound represented by (a). 16. The water-soluble hydrocarbon solvent has a general formula R ₂ —COO—R ₁ (wherein R ₁ is a methyl group or a tert-butyl group, R ₂ is a hydrogen atom, a methyl group or a tert-butyl group). The production method according to claim 2, 4, 6, or 9, which is a compound represented by (a). 17. The method according to claim 1, wherein the water-soluble hydrocarbon solvent is methyl acetate. 18. The water-soluble hydrocarbon solvent is acetic acid tert.
-Butyl, The manufacturing method of Claim 1 or 2. 19. The water-soluble hydrocarbon solvent is a compound represented by the general formula R ₁ —CO—R ₃ (wherein R ₁ and R ₃ are methyl groups or tert-butyl groups). The manufacturing method according to 3, 5, or 7. 20. The water-soluble hydrocarbon solvent is a compound represented by the general formula R ₁ —CO—R ₃ (wherein R ₁ and R ₃ are methyl groups or tert-butyl groups). The manufacturing method according to 4, 6, or 9. 21. The production method according to claim 1, 3, 5, 7, 11, 15 or 19, wherein the suspension polymerization is carried out at a temperature of 50 to 60 ° C. 22. The production method according to claim 2, 4, 6, 9, 12, 16 or 20, wherein the suspension polymerization is carried out at a temperature of 50 to 60 ° C. 23. The iodine compound is a compound represented by the general formula R ′ · I _m (wherein R ′ is a hydrocarbon group having 1 to 3 carbon atoms, and m is 1 or 2). 4,
The manufacturing method according to 6, 9, 12, 16, 20 or 22. 24. The production method according to claim 23, wherein the iodine compound is diiodomethane. 25. The fluoroelastomer comprises (A) vinylidene fluoride units and (B) hexafluoropropylene units, and the content ratio of (A) vinylidene fluoride units and (B) hexafluoropropylene units is by weight. The ratio is 55:45 to 75:25, wherein the oil-soluble organic peroxide is diisopropyl peroxydicarbonate, the water-soluble hydrocarbon solvent is methyl acetate, and the suspension polymerization temperature is 50 to 60 ° C. Item 3. The manufacturing method according to Item 1 or 2. 26. The fluoroelastomer comprises (A) vinylidene fluoride units, (B) hexafluoropropylene units and (C) tetrafluoroethylene units, and (A) vinylidene fluoride units and (B) hexafluoro units. The content ratio of the total of propylene units and (C) tetrafluoroethylene units is 65:35 to 99: 1 by weight.
And (A) a vinylidene fluoride unit and (B)
The content ratio with the hexafluoropropylene unit is 45:55 to 70:30 by weight, the oil-soluble organic peroxide is diisopropyl peroxydicarbonate, the water-soluble hydrocarbon solvent is methyl acetate, and the suspension is The production method according to claim 1 or 2, wherein the polymerization temperature is 50 to 60 ° C. 27. The fluorine-containing elastomer comprises (A) vinylidene fluoride units, (B) hexafluoropropylene units and (C) tetrafluoroethylene units, and (A) vinylidene fluoride units and (B) hexafluoro units. The content ratio of the total of propylene units and (C) tetrafluoroethylene units is 65:35 to 99: 1 by weight.
And (A) a vinylidene fluoride unit and (B)
The content ratio with the hexafluoropropylene unit is 45:55 to 70:30 by weight, the oil-soluble organic peroxide is diisopropyl peroxydicarbonate, the water-soluble hydrocarbon solvent is tert-butyl acetate, The production method according to claim 1 or 2, wherein the suspension polymerization temperature is 50 to 60 ° C. 28. The fluorine-containing elastomer comprises (A) vinylidene fluoride units, (B) hexafluoropropylene units and (C) tetrafluoroethylene units, and (A) vinylidene fluoride units and (B) hexafluoro units. The content ratio of the total of propylene units and (C) tetrafluoroethylene units is 65:35 to 99: 1 by weight.
And (A) a vinylidene fluoride unit and (B)
The content ratio with the hexafluoropropylene unit is 45:55 to 70:30 by weight, the oil-soluble organic peroxide is diisopropyl peroxydicarbonate, the water-soluble hydrocarbon solvent is methyl acetate, and an iodine compound. Is diiodomethane, and the suspension polymerization temperature is 50 to 60 ° C. 3. The production method according to claim 2.