Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1996-06-28
1999-04-06
Mulcahy, Peter D.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C08K 520
Patent
active
058919414
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a fluororubber composition and a molded article of a fluororubber. In particular, the present invention relates to a fluororubber composition which is excellent in mold releasability in a vulcanizing molding step, and a molded article produced by vulcanizing said composition.
PRIOR ART
Examples of the conventional molding methods of a rubber are molding in a mold using a compression molding press (heat press), extrusion molding with an extruder, and so on. In the compression molding, a suitable mold release agent should be selected and used.
In general, in the case of the fluororubber, an external mold release agent which is coated on the mold such as a silicone emulsion type one or fluorine containing one is used. But, the external mold release agent should be applied on the mold surface before every shot, and may cause mold contamination. A contemplated solution for such problems is an internal mold release agent. However, the internal mold release agent cannot solve the problem of mold contamination satisfactorily. In addition, the internal mold release agent has drawbacks that it often causes fusing failure, deterioration of physical properties of the molded article, etc. For example, JP-A-2-281062 discloses compounding of a mixture of a metal salt of an aliphatic carboxylic acid and an aliphatic bisamide or a N-substituted aliphatic amide in a fluororubber. When such internal mold release agent is used, some problems arise, that is, a mold releasability is insufficient, the physical properties of the molded article are deteriorated greatly, and so on.
Further, the conventional internal mold release agent has a drawback that a "thin burr" adheres to the molded article so that defective molded articles are produced. That is, when the molded article of the fluororubber is produced by the compression molding or extrusion molding, an unnecessary part which is called as a "thin burr" remains on the molded article. Since the "thin burr" has tackiness, it bends and adheres to the molded article and its removal is difficult. Then, the molded article having the adhered thin burr is subjected to secondary vulcanization, whereby the product is defective.
SUMMARY OF THE INVENTION
Objects of the present invention are to provide a fluororubber which is excellent in mold releasability, does not deteriorate properties, in particular, compression set of a molded article thereof, and makes a "thin burr" non-tacky, and also to provide a molded article of a fluororubber having excellent properties.
As a result of the extensive study to solve the above problems, it has been found that when the fluororubber containing a fatty acid monoamide is vulcanized and molded, the above problems can be solved, and then the present invention has been completed.
According to one aspect of the present invention, there is provided a fluororubber composition comprising a fluororubber, a vulcanizing agent and 0.1 to 5 wt. parts of a fatty acid monoamide per 100 wt. parts of said fluororubber.
According to another aspect of the present invention, there is provided a fluororubber composition comprising 100 wt. parts of a fluororubber, 0.1 to 5 wt. parts of a fatty acid monoamide and 0.1 to 5 wt. parts of a fluorine-containing surfactant.
According to a further aspect of the present invention, there is provided a molded article of a fluororubber which is obtained by vulcanizing and molding the above composition.
DETAILED DESCRIPTION OF THE INVENTION
Herein, the fluororubber means a fluorinated elastomeric polymer, and includes all of the known fluororubbers. Typical examples of the fluororubber are vinylidene fluoride/hexafluoropropene base rubber (preferred molar ratio of vinylidene fluoride/hexafluoropropene being 45-95:55-5), vinylidene fluoride/ tetrafluoroethylene/hexafluoropropene base rubber (preferred molar ratio of vinylidene fluoride/tetrafluoroethylene/hexafluoropropene being 45-90:1-35:5-50), vinylidene fluoride/chlorotrifluoroethylene base rubber, tetrafluoroethylen
REFERENCES:
patent: 5430103 (1995-07-01), Ohata et al.
Kunio Mori et al., Nippon Gomu Kyokaishi, vol. 62, No. 1, pp. 84-92 (1989) and its prevention (Abstract 111:8698).
Matsumoto Koji
Tanaka Hiroyuki
Tomoda Masayasu
Ueta Yutaka
Daikin Industries Ltd.
Mulcahy Peter D.
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