Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1994-09-30
1996-04-16
Lipman, Bernard
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
5253263, 525353, 525375, 525379, C08F 800
Patent
active
055083552
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a novel vulcanizable, fluorine-containing elastomer composition. More particularly, the present invention is concerned with a vulcanizable, fluorine-containing elastomer composition which is capable of providing a vulcanization product having not only excellent tensile properties, resistance to heat and oils, and sealability at high temperatures which are comparable to those of vulcanization products of conventional fluorine-containing elastomer compositions, but also having a remarkably improved compression set resistance which has not conventionally been achieved, and which elastomer composition per se is remarkably improved with respect to mold release properties, flowability, roll processability, and workability in vulcanization molding, particularly in vulcanization molding by injection.
BACKGROUND ART
In general, a vulcanization product of a fluorine-containing elastomer has excellent resistance to heat and oils and, therefore, has been widely utilized in various industrial fields, such as in the fields of automobiles, ships, aircrafts and hydraulic devices and general machine industries, and in the field of devices for the prevention of environmental pollution. Examples of vulcanization products of a fluorine-containing elastomer include O-rings, gaskets, oil seals, diaphragms, hoses, rolls and sheets. Recently, an improvement in productivity and a labor-saving have been earnestly desired in the production of vulcanization products. Accordingly, it has been desired to develop a fluorine-containing elastomer having excellent workability in a vulcanization molding thereof. Particularly, since vulcanization molding of a fluorine-containing elastomer by injection is advantageous from a viewpoint of not only an improvement in productivity but also a labor-saving, the demand for a fluorine-containing elastomer which is suitable for vulcanization molding by injection, has increased.
As mentioned above, a vulcanization product of a fluorine-containing elastomer composition has excellent resistance to heat and oils. However, a fluorine-containing elastomer is generally not satisfactory in mold processability due to the high viscosity thereof as compared to other types of elastomers. In order to improve processability of a fluorine-containing elastomer composition, it has been attempted to lower the molecular weight of the elastomer so as to increase the flowability of the elastomer composition. However, this attempt has been unsuccessful. That is, the obtained elastomer composition is disadvantageous not only in that its workability is poor in roll molding due to occurrence of an unfavorably strong adhesion of the elastomer composition to the roll, but also in that a low molecular weight elastomer is difficult to crosslink by a polyol vulcanization, so that the important properties of vulcanization products, such as compression set resistance, are likely to be unsatisfactory.
Further, when a fluorine-containing elastomer having a low molecular weight is vulcanization molded by injection, the resultant molded product is poor in mold release properties, so that problems arise in working efficiency. In addition, when an elastomer having a low molecular weight is used for producing a molded product having a complicated configuration, the molded product is likely to suffer cracking, breakage and swelling, leading to a lowering of yield and productivity.
In order to improve the processability of fluorine-containing elastomers, it has been proposed to use a processing aid, such as a higher fatty acid ester, a silicone compound and a low molecular weight polyethylene (see, for example, Examined Japanese Patent Application Publication No. 52-44896 corresponding to U.S. Pat. No. 4,065,419). However, when the processing aid is used in a small amount, a satisfactory improvement of processability cannot be achieved. On the other hand, when the processing aid is used in an amount sufficient to improve the processability, the vulcanization molded product becomes very poo
REFERENCES:
patent: 3622549 (1971-11-01), Keller
patent: 4151342 (1979-04-01), Uchino et al.
Saitou Hiroshi
Shibayama Shinichi
Toda Keiichi
Bromels Marilyn H.
E. I. Du Pont de Nemours and Company
Lipman Bernard
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