Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-11-07
2002-08-20
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S236000, C524S430000
Reexamination Certificate
active
06437028
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a crosslinkable elastic copolymer composition whereby polyol vulcanizability is excellent, and a vulcanizate excellent in heat resistance and oil resistance can be obtained.
BACKGROUND ART
It is known that an elastic copolymer having vinylidene fluoride (hereinafter referred to as VdF) copolymerized, exhibits an excellent mold release property and gives a vulcanizate having excellent heat resistance, oil resistance and compression set, when an organic polyhydroxy compound is used as a vulcanizing agent. Such a vulcanizate of an elastic copolymer is suitably used as an automobile part such as an oil seal. However, along with the trend for high performance of engine oil, the durability against engine oil having a large amount of an amine type additive incorporated, has become an important subject.
Especially, a vulcanizate of a composition containing a copolymer having a content of polymer units based on VdF as high as at least 35 mol %, such as a hexafluoropropylene (hereinafter referred to as HFP)/VdF type elastic copolymer or a HFP/VdF/tetrafluoroethylene (hereinafter referred to as TFE)type elastic copolymer, has had a problem such that the degree of deterioration due to the reaction of the amine type additive to the sites of the polymer units based on VdF, is substantial.
Whereas, a vulcanizate of a composition containing a TFE/propylene (hereinafter referred to as P)/VdF type elastic copolymer as a copolymer having a low content (such as not higher than 15 mol %) of polymer units based on VdF, is excellent in engine oil resistance. JP-A-6-157858 discloses that by employing an organic quarternary ammonium bisulfate as a vulcanization accelerator, it is possible to obtain an excellent vulcanizate even with a TFE/P/VdF type elastic copolymer, which has a content of polymer units based on VdF as low as 4 mol %. However, as shown in its Examples, a TFE/P/VdF type elastic copolymer having a content of polymer units based on VdF at a level of not higher than 5 mol %, has a vulcanization rate decreased as compared with a TFE/P/VdF type elastic copolymer having such a content as high as at least 10 mol %. In fact, if a relatively large amount of an organic quarternary ammonium bisulfate is incorporated in order to increase the vulcanization rate, there has been an adverse effect to the heat resistance or oil resistance of the vulcanizate.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a crosslinkable elastic copolymer composition which contains a TFE/P/VdF type elastic copolymer having a low content of polymer units based on VdF, which is excellent in polyol vulcanizability and which gives a vulcanizate excellent in heat resistance and oil resistance.
The present invention is firstly the following invention.
A crosslinkable elastic copolymer composition characterized in that it comprises:
(A) an elastic copolymer comprising from 35 to 65 mol % of polymer units based on TFE, from 20 to 50 mol % of polymer units based on P, and from 0.5 to 15 mol % of polymer units based on VdF,
(B) at least one member selected from the group consisting of an organic quaternary ammonium hydroxide represented by the general formula R
1
R
2
R
3
R
4
NOH (wherein R
1
to R
4
are the same or different C
1-20
hydrocarbon groups) or the following formula 1 (wherein R
5
is a hydrogen atom or a C
1-20
hydrocarbon group, and n is an integer of from 3 to 5), and a salt of an organic quaternary phosphonium compound with a nitrogen-containing heterocyclic compound:
(C) at least one member selected from an organic polyhydroxy compound and its derivative, and
(D) at least one member selected from a metal oxide and a metal hydroxide.
The present invention is secondly the following invention.
A crosslinkable elastic copolymer composition characterized in that it comprises:
(A) an elastic copolymer comprising from 35 to 65 mol % of polymer units based on TFE, from 20 to 50 mol % of polymer units based on P, and from 0.5 to 15 mol % of polymer units based on VdF,
(B) at least one member selected from the group consisting of an organic quaternary ammonium hydroxide represented by the general formula R
1
R
2
R
3
R
4
NOH (wherein R
1
to R
4
are the same or different C
1-20
hydrocarbon groups) or the following formula 1 (wherein R
5
is a hydrogen atom or a C
1-20
hydrocarbon group, and n is an integer of from 3 to 5), and a salt of an organic quaternary phosphonium compound with a nitrogen-containing heterocyclic compound:
(C) at least one member selected from an organic polyhydroxy compound and its derivative,
(D) at least one member selected from a metal oxide and a metal hydroxide, and
(E) an amine compound excluding the compound represented by the formula 1.
BEST MODE FOR CARRYING OUT THE INVENTION
The Mooney viscosity ML
1+10
(121° C.) as an index of the molecular weight of the elastic copolymer of component (A) in the composition of the present invention, is not particularly limited, but it is preferably within a range of from 5 to 150, particularly preferably within a range of from 10 to 100, as a kneading operation is carried out usually at the time of the preparation of the composition.
Component (A) wherein the proportion of polymer units based on VdF is from 0.5 to 15 mol %, preferably from 0.5 to 10 mol %, is capable of giving a vulcanizate which is excellent in engine oil resistance. Component (A) wherein the proportion of polymer units based on TFE is from 35 to 65 mol %, preferably from 45 to 65 mol %, has excellent heat resistance and chemical resistance and component (A) wherein the proportion of polymer units based on propylene is from 20 to 50 mol %, preferably from 35 to 50 mol %, is capable of giving a vulcanizate having excellent oil resistance.
Component (A) may contain or may not contain unsaturated bonds as readily vulcanizable sites in the copolymer. By simply heat-treating component (A) or heat-treating it in the presence of a basic substance or an acidic substance, it is possible to remove HF from polymer units based on VdF and introduce carbon-carbon unsaturated bonds into the polymer units. Further, unsaturated bonds may likewise be introduced by treating a water dispersion of component (A) obtained by polymerization, with a basic substance such as potassium hydroxide. By introducing such unsaturated bonds, the vulcanizability of component (A) can be improved.
The amount of unsaturated bonds to be introduced is preferably from about 1 to 50 mol % of the polymer units based on VdF. If the amount is less than this range, the effect for improvement of the vulcanizability tends to be small, and if it exceeds this range, the properties of the resulting vulcanizate may sometimes deteriorate.
For the production of the elastic copolymer of component (A), various polymerization systems may be employed such as bulk polymerization, suspension polymerization, emulsion polymerization or solution polymerization, and it is possible to optionally adopt a catalyst polymerization method employing a radical polymerization initiator, an ionizing radiation polymerization method or a redox type polymerization method.
Component (B) functioning as a vulcanization accelerator is at least one member selected from the group consisting of an organic quaternary ammonium hydroxide represented by the general formula R
1
R
2
R
3
R
4
NOH (wherein R
1
to R
4
are the same or different C
1-20
hydrocarbon groups) or the following formula 1 (wherein R
5
is a hydrogen atom or a C
1-20
hydrocarbon group, and n is an integer of from 3 to 5), and a salt of an organic quaternary phosphonium compound with a nitrogen-containing heterocyclic compound:
Component (B) has an activity substantially higher than the organic quarternary ammonium bisulfate, and when component (B) is employed, an excellent vulcanizate can be obtained even with a TFE/P/VdF type elastic copolymer having a low content of polymer units based on VdF.
The following compounds may be exemplified as component (B). These compounds may be used alone, respectively, or may be
Kaneko Takeo
Miwa Tetsuya
Nakamura Jun-ichi
Saito Masayuki
Asahi Glass Company Limited
Cain Edward J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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