Fluorine-containing copolymer and composition thereof

Details Fluorine-containing copolymer and composition thereof Fluorine-containing copolymer and composition thereof

2000-09-28

2001-10-09

Zitomer, Fred (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S242000, C526S247000, C526S250000, C526S255000, C526S345000, C526S351000, C526S352000

Reexamination Certificate

active

06300446

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a novel fluorine-containing copolymer having good vulcanizability, and a molded product having good heat resistance and oil resistance, which is obtained by vulcanizing a vulcanizable composition containing it.
BACKGROUND ART
Fluorine rubber is preferably employed for automobile parts such ag oil seals, as a rubber excellent in oil resistance. However, along with the trend for high performance of engine oil, durability of an engine oil having an amine type additive incorporated in a large amount has become an important subject. A vulcanizate of copolymer having VdF copolymerized, such as a am hexafluoropropylene (hereinafter referred to as HFP)/vinylidene fluoride (hereinafter referred to as VdF) polymer, a HFP/VdF/tetrafluoroethylene (hereinafter referred to as TFE) copolymer or a TFE/propylene/VdF copolymer, has been poor in engine oil resistance, and a vulcanizate of a TFE/propylene copolymer is excellent in engine oil resistance, but has had a problem that it is inferior in vulcanizability.
DISCLOSURE OF THE INVENTION
The present invention has an object to provide a fluorine-containing copolymer excellent in vulcanizability, a vulcanizdble Composition containing such a copolymer, and a molded product excellent in heat resistance and oil resistance, which can be obtained by vulcanizing the composition.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention provides a fluorine-containing copolymer which comprises from 30 to 70 mol % of polymer units based on (A) TFE, from 0.1 to 40 mol % of polymer units based on (B) at least one member selected from the group consisting of vinyl fluoride (hereinafter referred to ag VF) and vinyl chloride (hereinafter referred to as VC) and from 20 to 69.9 mol % of polymer units based on (C) a polymerizable compound other than (A) and (B), and which has a Mooney viscosity ML
1+10
(100° C.) of from 10 to 200 as an index of the molecular weight.
Further, it provides a vulcanizable composition comprising (D) the above mentioned fluorine-containing copolymer, (E) a vulcanizing agent, (F) an acid-receiving agent and (G) a vulcanization accelerator.
The proportion of polymer units based on TFE of component (A) is from 30 to 70 mol %, preferably from 35 to 65 mol %. If it is less than 30 mol %, the fluorine content in the copolymer is low, whereby the heat resistance and oil resistance of the vulcanizate tend to be inferior, and if it exceeds 70 mol %, the function of the vulcanizate as a rubber elastic body tends to deteriorate. The polymer units based on VF or VC of component (B) will serve as vulcanization sites, and their proportion is from 0.1 to 40 mol %, preferably from 0.5 to 15 mol %, more preferably from 0.5 to 10 mol %. If it is less than 0.1 mol %, the vulcanizability tends to be inadequate, and if it exceeds 40 mol %, the heat resistance or oil resistance of the obtained vulcanizate tends to be low.
The proportion of the polymer units based on the polymerizable compound of component (C) is from 20 to 69.9 mol %, preferably from 30 to 65 mol %.
The polymerizable compound (C) may, for example, be a fluorine-containing olefin, a fluorine-containing vinyl ether, an alkyl vinyl ether or a hydrocarbon type olefin. At least one member selected therefrom will be copolymerized.
The fluorine-containing olefin may specifically be, for example, VdF, HFP, pentafluoropropylene, trifluoroethylene or chlorotrifluoroethylene.
The fluorine-containing vinyl ether is not particularly limited, but it may, for example, be preferably a perfluorovinyl ether represented by a general formula of CF
2
═CFO(CF
2
CFXO)
n
R
f
(wherein R
f
is a C
1-12
perfluoroalkyl group, X is a fluorine atom or a trifluoromethyl group, and n is an integer of from 0 to 6). In the general formula, it is preferred that R
f
is a C
1-5
perfluoroalkyl group, n is from 0 to 3, and X is a trifluoromethyl group, from the viewpoint of easy vailability. specifically, CF
2
═CFOCF
3
, CF
2
═CFOC
2
F
5
, CF
2
═CFOC
3
F
7
, CF
2
═CFOC
5
F
11
or CF
2
═CFOCF
2
CF (CF
3
) OC
3
F
7
, may, for example, be mentioned.
Further, a fluorine-containing vinyl ether which is not perfluorinated, such as CF
2
═CFO(CF
2
)pH [wherein p is an integer of from 2 to 8] or CF
2
═CFOCH
2
(CF
2
)
q
F [wherein q is an integer of from 1 to 7], may also be employed.
Particularly, perfluorovinyl ether is preferably employed.
The alkyl vinyl ether may be represented by a general formula of CH
2
═CHOR (wherein R is an alkyl group or a cycloalkyl group). The alkyl vinyl ether is preferably one having the above general formula wherein R is a C
1-6
alkyl group or a C
3-6
cycloalkyl group, and R may be straight chained, branched or cyclic.
Specifically, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, isopropyl vinyl ether, isobutyl vinyl ether or cyclohexyl vinyl ether, may, for example, be mentioned.
The hydrocarbon type olefin is not particularly limited. However, in the present invention, ethylene, propylene or isobutylene is preferred which has a small chain transfer constant. Further, in the fluorine-containing copolymer of the present invention, as one type of (C), vinyl acetate, vinyl chloroacetate, chloroethyl vinyl ether, glycidyl vinyl ether or allyl glycidyl ether may, for example, be copolymerized.
The fluorine-containing copolymer of the present invention has a Mooney viscosity ML
1+10
(100° C.) of from 10 to 200, preferably from 15 to 150, as an index of the molecular weight. If the Mooney viscosity is outside this range, the function of the vulcanizate as a rubber elastic body tends to deteriorate.
For the production of the fluorine-containing copolymer of the present invention, conventional polymerization methods may be employed. Specifically, in bulk polymerization, suspension polymerization, emulsion polymerization or solution polymerization, a catalytic polymerization method employing a polymerization initiator such as a peroxide or an azo compound, an ionizing radiation polymerization method or a redox type polymerization method may, for example, be optionally carried out.
The copolymerization can be carried out in an organic solvent such as a fluorine-containing hydrocarbon type solvent such as CF
3
CCl
2
F, CClF
2
CF
2
CHClF, CF
3
CF
2
CHFCHFCF
3
, F (CF
2
)
6
H, F (CF
2
)
6
F or C
4
F
9
CH
2
CH
3
or an alcohol type solvent such as t-buthanol, CF
3
CH
2
OH or C
4
F
9
CH
2
CH
2
OH.
As the polymerization temperature, a temperature of from −40° C. to +150° C. may be employed, and as the polymerization pressure, a relatively low pressure of from 1 to 50 kg/cm
2
may be employed. Further, using an queous medium, suspension polymerization or emulsion olymerization may be carried out.
In the emulsion polymerization, an anionic emulsifier such as a perfluorocarboxylic acid salt, an alkyl benzene sulfonic acid salt, an alkyl naphthalene sulfonic acid salt, an alkyl ether sulfuric acid ester or a phosphoric acid ester, and a nonionic emulsifier such as an alkyl phenol ethylene oxide adduct, a higher alcohol ethylene oxide adduct or an ethylene oxide/propylene oxide block copolymer, may preferably be employed.
In the suspension polymerization or the emulsion polymerization, a reaction accelerator, a dispersion stabilizer such as methyl cellulose, polyvinyl alcohol, liquid paraffin or t-buthanol, or the like, may suitably be employed, and further, control of the molecular weight may optionally be carried out by employing a chain transfer agent such as acetone, isopropyl alcohol, sec-buthanol, methanol, diethyl malonate or tetrahydrofuran. Further, a polymerization initiator such as a peroxide, an azo compound or a persulfate may be employed, or the copolymerization reaction may be carried out by radiation of ionizing radiation such as &ggr;-ray from
60
Co.
The polymerization in an aqueous medium can be carried out, for example, at a temperature of from 50 to 100° C. under a pressure of from 5 to 200 kg/cm
2
. Otherwise, the polyme

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