JPH05230152A - Copolymer containing fluorovinyl ether - Google Patents

Abstract

PURPOSE:To obtain the title copolymer which contains the units derived from a specific fluorovinyl ether and the units derived from ethylenically unsaturated compound, thus being useful as a sealant, adhesive and coating or the like because of its improved low-temperature properties. CONSTITUTION:The objective copolymer comprises the recurring units derived from a specific fluorovinyl ether and the units derived from an ethylenically unsaturated compound where the amount of the compound of formula I is 5 to 60 mole % based on the ethylenically unsaturated compound and the intrinsic viscosity in methyl ethyl ketone at 35 deg.C is 0.2 to 1.8. The compound of formula I is usually obtained by reaction of an acyl fluoride of formula II with a lower alcohol such as methanol, treatment of the formed ester with an alkali hydroxide such as sodium hydroxide and heating the resultant salt at 150 to 250 deg.C under reduced pressure.

Description

Detailed Description of the Invention

[0001]

This invention relates to copolymers containing fluorovinyl ether.

[0002]

BACKGROUND OF THE INVENTION Copolymerization of fluoroolefins with other fluoroolefins or fluorine-free olefins results in a variety of resins, from resinous to elastomeric, depending on the type and proportion of fluoroolefins and other monomers in the copolymer. A copolymer is obtained. This copolymer can be molded into mechanical components such as O-rings, flange seals, gasket stock, pump diaphragms and liners, and is particularly useful when special resistance to heat and corrosive fluids is required.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide polymers, especially elastic polymers, with improved low temperature properties.

[0004]

SUMMARY OF THE INVENTION The gist of the present invention is the formula: XCH ₂ CF ₂ CF ₂ (OCH ₂ CF ₂ CF ₂ ) mOCF═CF ₂ (I) where X is fluorine and m is 0. Represents an integer of 5; ] And a repeating unit derived from at least one ethylenically unsaturated compound, wherein the amount of fluorovinyl ether (I) is relative to the number of moles of the ethylenically unsaturated compound. 5 to 60 mol%, and the intrinsic viscosity measured at 35 ° C. using methyl ethyl ketone as a solvent is 0.2 to 1.
8 is a copolymer.

Fluorovinyl ether (I) is disclosed in
It can be derived from the corresponding acid fluoride prepared by the method described in JP-A No. 0-137928 or JP-A No. 60-136536. Generally, the fluorovinyl ether (I) can be prepared from the corresponding acid fluoride as follows.

First, the formula: XCH ₂ CF ₂ CF ₂ (OCH ₂ CF ₂ CF ₂ ) mOC (CF ₃ ) F-COF [wherein X and m have the same meanings as described above]. ] By reacting an acyl fluoride with a lower alcohol such as methanol, and the formula: XCH ₂ CF ₂ CF ₂ (OCH ₂ CF ₂ CF ₂ ) mOC (CF ₃ ) F—COOCH ₃ [wherein, X and m are It has the same meaning as above. ] To obtain the ester. Then, the obtained ester is reacted with an alkali hydroxide (MOH) such as sodium hydroxide,
_{Formula: XCH 2 CF 2 CF 2 (} OCH 2 CF 2 CF 2) mOC (CF 3) F-COOM [ wherein, X and m are as defined above. ] The salt shown below is produced | generated and this is heated under reduced pressure or an inert gas atmosphere, such as nitrogen, at 150-250 degreeC, and the fluoro vinyl ether (I) is obtained.

The ethylenically unsaturated compound which copolymerizes with the fluorovinyl ether (I) may be any of the known monomers. Ethylenically unsaturated compounds include fluorine-free ethylenically unsaturated compounds ethylene, propylene, butylene, carboxylic acid vinyl esters (for example, vinyl acetate), vinyl ethers (for example, methyl vinyl ether, ethyl vinyl ether), vinyl chloride, vinylidene. Chloride, acrylic acid and methacrylic acid, tetrafluoroethylene which is an ethylenically unsaturated compound containing fluorine, trifluoroethylene, chlorotrifluoroethylene, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, hexafluoroisobutene, Perfluorocyclobutene, perfluoro (methylcyclopropylene), perfluoroallene, α, β, β-trifluorostyrene, perfluorostyrene, perfluor Alkyl vinyl ethers (for example, perfluoro (methyl vinyl ether), perfluoro (propyl vinyl ether)), perfluoro (alkyl vinyl polyether) s, polyfluoroacrylic acid, polyfluorovinyl acetic acid, polyfluorovinyl ether sulfonic acid and polyfluorodiene The kind is illustrated.

Fluorovinyl ether (I) in the copolymer
May vary depending on the type of copolymer produced. Generally, the amount of fluorovinyl ether (I) is 5 to 60 mol%, preferably 10 to 50 mol%, based on the total number of moles of the other monomers.

According to a preferred embodiment of the invention, the copolymer comprises 20 to 100 mol% of repeating units derived from vinylidene fluoride, at least one other ethylenically unsaturated copolymerizable with vinylidene fluoride. From 80 to 0 mol% of repeating units derived from the compound and from 5 to 60 mol% of repeating units derived from fluorovinyl ether (I) based on the total moles of vinylidene fluoride and other ethylenically unsaturated compounds Become. Fluoro vinyl ether
The amount of (I) is preferably 10 to 50 mol%.

Polymerization can be carried out in the form of bulk polymerization, suspension polymerization, solution polymerization, or emulsion polymerization using a water-soluble or oil-soluble peroxide in the presence of a perfluoroemulsifier. Solvents used for solution polymerization include dichlorodifluoromethane, trichlorofluoromethane, chlorodifluoromethane, 1,1,2-trichloro-1,2,2-
Trifluoroethane, 1,2-dichloro-1,1,2,2-
Tetrafluoroethane, 1,1,2,2-tetrachloro-
A highly fluorinated solvent such as 1,2-difluoroethane, perfluorocyclobutane or perfluorodimethylcyclobutane is preferably used.

In the bulk, suspension and solution polymerization forms, organic initiators can generally be used. Among them, the most preferred initiators are the highly fluorinated peroxides, RfCO-O-O-CORf (where Rf is a perfluoroalkyl group, ω-hydroperfluoroalkyl group or perchlorofluoro group). A diacyl peroxide represented by (an alkyl group) is particularly preferable.

The molecular weight can be easily adjusted by adding a chain transfer agent. Examples of the chain transfer agent include hydrocarbons having 4 to 6 carbon atoms, alcohols, ethers, organic halides (for example, CCl ₄ , CBrCl ₃ , CF ₂ BrC).
FBrCF ₃ , CF ₂ I ₂ ) and the like can be used advantageously. Fluorocarbon iodides (eg CF ₂ I ₂ ,
When I (CF ₂ ) ₄ I, CF ₂ ═CFCF ₂ CF ₂ I) is used as a chain transfer agent, iodine is bound to a molecular end and is still in a radically active state. It is possible to perform peroxide vulcanization using peroxide as a radical source in the presence of a polyfunctional unsaturated compound such as triaryl cyanurate.

The polymerization temperature is determined by the decomposition temperature of the initiator, but is preferably 0 to 130 ° C. Usually, the polymerization pressure is preferably 5 to 50 kg / cm ² G.

The copolymers of this invention can be cured in the presence of various crosslinking sources. Radiation as a crosslinking source
High-energy electromagnetic waves such as (α-rays, β-rays, γ-rays, electron rays, X-rays) and ultraviolet rays can also be used, but organic peroxide compounds are preferably used.

The amount of the organic peroxide compound used is 0.05 to 10 parts by weight, preferably 1.0 to 5 parts by weight, based on 100 parts by weight of the copolymer.

As the organic peroxide compound, a compound which easily generates a peroxy radical in the presence of heat or a redox system is generally preferable, for example, 1,1-bis (t-butylperoxy) -3,5, 5-Trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide α, α'-
Bis (t-butylperoxy) -p-diisopropylbenzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) (Oxy) -hexyne-3, benzoyl peroxide, t-butyl peroxybenzene, 2,5-dimethyl-
Examples include 2,5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate and the like. Above all,
Preferred is the dialkyl type. Generally, the type and amount of peroxide used are selected in consideration of the amount of active —O—O—, decomposition temperature, and the like.

When an organic peroxide compound is used, a remarkable curing can be seen by appropriately using a crosslinking aid or a co-crosslinking agent together. The crosslinking aid or co-crosslinking agent is basically effective as long as it has a reaction activity with respect to a peroxy radical and a polymer radical, and the kind is not particularly limited. The preferred one is
Triallyl cyanurate, triallyl isocyanurate, triallyl formal, triallyl trimellitate, N, N'-m-phenylene bismaleimide, dipropargyl terephthalate, diallyl phthalate, tetraallyl terephthalamide, triallyl phosphate, etc. Can be mentioned. The amount used is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 100 parts by weight, based on 100 parts by weight of the copolymer.
5 parts by weight. In addition, as a blend co-crosslinkable, silicone oil, silicone rubber,
Ethylene / vinyl acetate copolymer, 1,2-polybutadiene, fluorosilicone oil, fluorosilicone rubber,
Fluorophosphazene rubber, hexafluoropropylene / ethylene copolymer, tetrafluoroethylene / propylene copolymer, and other polymers having radical reactivity are used. The amount of these used is not particularly limited, but should not be so large as to essentially impair the properties of the copolymer of the present invention.

Further, a pigment for coloring the copolymer,
Fillers, reinforcing agents, etc. are used. Commonly used fillers or reinforcing agents are inorganic materials such as carbon black, TiO ₂ , SiO ₂ , clay and talc, and organic materials such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, Examples thereof include fluoropolymers such as tetrafluoroethylene / ethylene copolymer and tetrafluoroethylene / vinylidene fluoride copolymer.

As a means for mixing these hardening components, an appropriate method is adopted depending on the viscoelasticity and form of the material, and in the case of a solid state, an ordinary open roll or powder mixer is used. In the case of a liquid, a usual mixer is used as appropriate. Of course, it is also possible to dissolve or disperse solid components in a solvent and then mix and disperse them.

The vulcanization temperature and time depend on the type of peroxide used, but normally, the press vulcanization is 120.
Perform at 5 to 30 minutes at a temperature of ~ 200 ° C, oven vulcanization is 1
It is performed at a temperature of 50 to 250 ° C. for 1 to 24 hours.

The copolymer of the present invention can be effectively used as a general molding material, a sealant, an adhesive, a paint, etc. in a place where heat resistance, oil resistance, chemical resistance, solvent resistance and the like are required.

Fluorovinyl ether (I) can be copolymerized with other fluoroolefins to form a copolymer in which the end of the side chain of the copolymer is extremely reactive. For example, with tetrafluoroethylene. Copolymerize,
After that, the end of the side chain is converted to
It is also easy to convert it to a hydrophilic group such as a carboxyl group or sulfonic acid group. Such a hydrophilic group-introduced copolymer can be used as an ion exchange membrane having excellent heat resistance and chemical resistance, and more generally, a hydrophilic diaphragm, filtration membrane,
It can be applied as a separation membrane. It is also useful as a biocompatible material.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to Reference Examples, Examples and Comparative Examples.

Reference Example 1 2,2,3-trifluoropropionyl fluoride (FC
H ₂ CF ₂ COF) manufacturing stirrer, was condenser and a dropping funnel marked with 5l flask carbon tetrachloride 360ml and the placed of aluminum chloride 108g the temperature to 30 to 35 ° C.. While stirring 2,
1800 g of 2,3,3-tetrafluorooxetane was added dropwise from the dropping funnel over 2 hours. After that, 90 g of aluminum chloride was divided into 3 times to complete the reaction.
30 g was added every hour. The temperature in the system is 27-29
After stirring at ℃ for 4 hours, the title compound 2,2,3-trifluoropropionylfluoride 1 was distilled off.
130 g are obtained. Boiling point 23-23.5 ° C.

Reference Example 2 2,2,5,5,6,6,7-heptafluoro-4-oxa-
Heptanoyl fluoride (FCH ₂ CF ₂ CF ₂ OCH ₂
Manufacture of CF ₂ COF) In a 5 liter flask equipped with a stirrer, a condenser and a dropping funnel,
2,5,3-Trifluoropropionyl fluoride obtained in Reference Example 1 (1059 g), crown ether (5 g), cesium fluoride (40 g), and monoglyme (1000 ml) were added, and the mixture was stirred at 15 ° C to 20 ° C for 2,2,3,3-tetrahydrofuran. 1515 g of fluorooxetane was slowly added dropwise over 3 hours and 30 minutes. After completion of the dropping, stirring was continued for 5 hours while maintaining the internal temperature at 15 ° C to 20 ° C. Then, the reaction solution was distilled under reduced pressure to obtain 300 g of the title compound 2,2,5,5,6,6,7-heptafluoro-4-oxa-heptanoyl fluoride. Boiling point: 62-64 ° C (80 mmHg).

Reference Example 3 2,2,5,5,6,6,9,9,10,10-decafluoro-
4,8-Dioxa-undecanoylfluoride (FCH
₂ CF ₂ CF ₂ OCH ₂ CF ₂ CF ₂ OCH ₂ CF ₂ COF) 2,2,5,5,6,6, using the same procedure as in Reference Example 2.
264 g of 9,9,10,10-decafluoro-4,8-dioxa-undecanoylfluoride were obtained. Boiling point: 23
℃ (5mmHg).

Reference Example 4 Production of perfluoro (6,6-dihydro-3-oxa-1-hexene) (FCH ₂ CF ₂ CF ₂ OCF = CF ₂ ) 88 g of cesium fluoride and 34 ml of tetraglyme
2,3,4 obtained in Reference Example 1 in a 3-liter four-necked flask containing
-Trifluoropropionyl fluoride 1055g
Was added. The temperature in the flask under stirring is -10 to -15 ° C.
Hexafluoropropylene oxide was added from a cylinder at a rate of refluxing with a dry ice cooler while maintaining the above.
After 52 hours from the start of the reaction, the addition of hexafluoropropylene oxide was stopped, and 1324 ml of methanol was added while cooling with ice water, followed by washing with water several times, and then distilling F
Were separated _{CH 2 CF 2 CF 2 OC (} CF 3) FCOOCH 3. Yield: 804g, Boiling point: 138 ° C.

Subsequently, the produced methyl ester was placed in a 2 l flask and phenolphthalein was added as a PH indicator to 60 ml.
The saponification reaction was performed with 10 wt% NaOH / methanol solution at ˜70 ° C. From the slightly pink colored viscous solution, methanol was distilled off under reduced pressure and vacuum drying was carried out at 100 ° C. until a constant weight was reached to obtain 810 g of a solid matter.

Next, the solid was thoroughly crushed and placed in a 3 l flask connected to a trap sufficiently cooled with dry ice, and the atmosphere was sufficiently replaced with nitrogen gas. 150 ° C over 5 hours
When heating was continued from 0 to 250 ° C., 542 g of liquid accumulated in the trap. This was distilled to give the title compound perfluoro (6,6-dihydro-3-oxa-1-
324 g of hexene) was obtained. Boiling point: 61-62 ° C.

Reference Example 5 Perfluoro (6,6,10,10-tetrahydro-3,7-
_{Dioxa-1-decene) (FCH 2 CF 2 CF 2} OCH 2 CF 2
Manufacture of CF ₂ OCF = CF ₂ ) In the same manner as in Reference Example 4, 2, 2,
5,5,6,6,7-Heptafluoro-4-oxa-heptanoylfluoride 204 g to the title compound perfluoro (6,6,10,10-tetrahydro-3,7-dioxa-
65 g of 1-decene) was obtained. Boiling point: 44 ~ 45 ℃ (13mm
Hg).

Reference Example 6 Perfluoro (6,6,10,10,14,14-
Hexahydro-3,7,11-trioxa-1-tetradecene) (FCH ₂ CF ₂ CF ₂ OCH ₂ CF ₂ CF ₂ OCH ₂
Manufacture of CF ₂ CF ₂ OCF = CF ₂ ) In the same manner as in Reference Example 4, manufactured in Reference Example 3,
2,5,5,6,6,9,9,10,10-decafluoro-4,
The title compound perfluoro (6,6,10,10,14,1) was obtained from 321 g of 8-dioxa-undecanoylfluoride.
54 g of 4-hexahydro-3,7,11-trioxa-1-tetradecene) was obtained. Boiling point: 88 ~ 89 ℃ (13mm
Hg).

Example 1 F was put into a 100 ml pressure-resistant glass ampoule equipped with a bulb.
CH ₂ CF ₂ CF ₂ OCF = CF ₂ 6.9 g, 1,1,2-trichloro-1,2,2-trifluoroethane (hereinafter, R-
Abbreviated as 113. ) 10 ml and 2,4,5-trichloroperfluorohexanoyl peroxide R-11
0.5 ml of 3 solutions (concentration: 0.7 g / ml) was charged, cooled with dry ice / methanol solution, and then the system was replaced with nitrogen. Then, 6.8 g of VdF was charged and reacted at 20 ± 1 ° C. for 20 minutes with shaking. With the reaction, the gauge pressure in the system decreased from 6.3 kg / cm ² before the reaction to 5.5 kg / cm ² . The unreacted monomer was released, the content was dissolved in acetone and taken out, and then it was released into pure water for precipitation to separate the copolymer. Vacuum-dry until constant weight of copolymer 2.
2 g was obtained. From the ¹ H-NMR analysis, the composition ratio of this copolymer was VdF: (FCH ₂ CF ₂ CF ₂ OCF = CF ₂ ) = 71.
It was 8: 28.2 (molar ratio). The glass transition temperature of the copolymer is -3 as measured by a scanning calorimeter (DSC).
It was 0 ° C., and it was found that good low temperature characteristics were exhibited. The intrinsic viscosity [η] of the copolymer was 0.40 (measuring solvent: methyl ethyl ketone (MEK), temperature: 35 ° C).

EXAMPLE 2 F was placed in a 100 ml pressure-resistant glass ampoule equipped with a bulb.
_{(CH 2 CF 2 CF 2 O} ) 2 CF = CF 2 10.8g, R-11
3 10 ml and a solution of 2,4,5-trichloroperfluorohexanoyl peroxide in R-113 (0.44 g)
/ Ml) 0.5 ml was charged and the system was replaced with nitrogen gas after cooling with dry ice / methanol solution. Then Vd
Charge F5.7g and shake at 20 ± 1 ℃ for 35 minutes.
It was made to react. As the reaction progressed, the gauge pressure in the system decreased from 9.8 kg / cm ² before the reaction to 6.8 kg / cm ² . Unreacted monomers were released, the contents were dissolved in acetone and taken out, and then the contents were released into water and precipitated to separate the copolymer.
The weight of the copolymer after vacuum drying was 10.2 g. The composition ratio of this copolymer was determined by ¹ H-NHR analysis to be VdF: [F (C
_{H 2 CF 2 CF 2 O)} 2 CF = CF 2] = 72.8: 27.2 (molar ratio), the glass transition temperature of the copolymer -30.5%
Met. The intrinsic viscosity of the copolymer was 0.72 (measuring solvent: MEK, temperature: 35 ° C).

Example 3 Instead of FCH ₂ CF ₂ CF ₂ OCF = CF ₂ , F (CH ₂ CF
Using _{2 CF 2 O) 3 CF =} CF 2 14.7g, when is reacted in the same manner as in Example 1 except that the reaction time is between 23 minutes, the system in gauge pressure from 9.8 kg / cm ² 8.0 kg / cm ²
Has changed. The amount of the copolymer after vacuum drying was 16.2 g. The compositional molar ratio of the copolymer is VdF: [F (CH ₂ -C
_{F 2 CF 2 O) 3 CF} = CF 2] = 73.9: 26.1, a glass transition temperature of -42.0 ℃. The intrinsic viscosity was 0.79 (measuring solvent: MEK, temperature 35 ° C.).

Example 4 When the reaction was carried out in the same manner as in Example 1 except that 3.5 g of TFE was charged instead of VdF and the reaction time was 1 hour, the system gauge pressure was 2.2 kg / cm ² to 1. It changed to 0.8 kg / cm ² . The weight of the copolymer after vacuum drying was 0.7 g. The copolymer was an elastic body, and its melting point was not observed. The glass transition temperature was 8.5 ° C.

Examples 5 to 9 Reactions were carried out in the same manner as in Example 1 except that the charged amounts of VdF and FCH ₂ CF ₂ CF ₂ OCF = CF ₂ were changed, and TFE was further added. Table 1 shows the charged amount in each case, the weight of the obtained copolymer, the composition ratio, the glass transition temperature and the intrinsic viscosity (measuring solvent: MEK, temperature: 35 ° C.).
The composition molar ratio of the copolymer is ¹ H-NMR and ¹⁹ F-NMR.
Obtained from analysis. In the table, "FM" and "DLP" are respectively _{"F-CH 2 CF 2 CF 2} OCF = CF 2 ," and "2,4,
R-113 solution of 5-trichloroperfluorohexanoyl peroxide (concentration 0.7 g / ml) ".

[0037]

[Table 1] Example 5 6 7 8 9 Charge VdF (g) 0.6 1.8 5.5 0.5 1.4 TFE (g) 0.2 0.7 2.2 0.5 1.4 FM (g) 6.9 6.9 6.9 6.9 6.9 R-113 10 10 10 10 10 DLP (ml ) 0.5 0.5 0.5 0.5 0.5 Reaction temperature (℃) 20 20 20 20 20 Reaction time (min) 30 20 15 30 20 Copolymer weight (g) 0.6 1.0 1.6 0.5 1.0 VdF (mol%) 47.9 51.7 57.9 35.6 42.0 TFE ( Mol%) 3.6 9.4 15.4 27.9 25.9 FM (mol%) 48.5 38.9 26.7 36.5 32.1 Tg (° C) −20 −33 −36.5 −44.5 −30 [η] − 0.53 0.61 − 0.58

Example 10 0.8 g of ethylene was added in place of VdF, and the reaction time was 20
The reaction was carried out in the same procedure as in Example 1 except that the time was changed to minutes. Gauge pressure in the system is 7.2kg / cm ² to 6.7kg / cm ²
Has changed. The weight of the copolymer after vacuum drying was 0.8 g, and the composition ratio of this copolymer was ethylene: (FCH ₂ CF ₂
CF ₂ OCF = CF ₂ ) = 56.3: 43.7 (molar ratio). The glass transition temperature was -11 ° C. The intrinsic viscosity of the copolymer was 0.30 (measuring solvent: MEK, temperature 35 ° C.).

[0039]

The copolymers of the present invention have improved low temperature properties.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Tetsuo Shimizu 2-27-104, Shin-Koriyama, Ibaraki City, Osaka Prefecture

Claims (3)

[Claims] 1. A formula: XCH ₂ CF ₂ CF ₂ (OCH ₂ CF ₂ CF ₂ ) mOCF═CF ₂ (I) [wherein, X represents fluorine, and m represents an integer of 0 to 5. ] And a repeating unit derived from at least one ethylenically unsaturated compound, wherein the amount of fluorovinyl ether (I) is relative to the number of moles of the ethylenically unsaturated compound. 5 to 60 mol%, and the intrinsic viscosity measured at 35 ° C. using methyl ethyl ketone as a solvent is 0.2 to 1.
The copolymer which is 8. 2. The ethylenically unsaturated compound is ethylene,
Propylene, butylene, carboxylic acid vinyl ester, vinyl ether, vinyl chloride, vinylidene chloride, acrylic acid, methacrylic acid, tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, pentafluoro propylene,
Hexafluoroisobutene, perfluorocyclobutene, perfluoro (methylcyclopropylene), perfluoroallene, α, β, β-trifluorostyrene, perfluorostyrene, perfluoroalkyl vinyl ethers, perfluoro (alkyl vinyl polyether) s A polyfluoroacrylic acid, a polyfluorovinylacetic acid, a polyfluorovinyl ether sulfonic acid, and a polyfluorodiene group.
The copolymer described. 3. 20-100 mol% of repeating units derived from vinylidene fluoride, 80-0 mol% of repeating units derived from at least one other ethylenically unsaturated compound copolymerizable with vinylidene fluoride. And a copolymer of vinylidene fluoride and other ethylenically unsaturated compounds in an amount of 5 to 60 mol% based on the total number of moles of the fluorovinyl ether (I).