Coating processes – With pretreatment of the base – Etching – swelling – or dissolving out part of the base
Patent
1998-09-09
2000-06-13
Cameron, Erma
Coating processes
With pretreatment of the base
Etching, swelling, or dissolving out part of the base
427387, 4273935, 4274301, B05D 118, B05D 302
Patent
active
06074698&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for producing a surface modified rubber, a surface modified rubber and a seal material. More particularly, the present invention is concerned with a process for producing a surface modified rubber which enables obtaining a rubber being excellent in low friction, nonadherence, abrasion resistance and plasma resistance while retaining compression set, rubber elasticity, mechanical strength and deformation follow-up properties inherently possessed by a rubber material and is concerned with such a surface modified rubber and a seal material obtained from the surface modified rubber.
BACKGROUND ART
Rubber moldings are widely used as seal materials in, for example, chemical equipment, semiconductor producing apparatus, chemical liquid piping and tanks and food producing apparatus.
The rubber moldings are endowed with low friction, nonadherence and abrasion resistance by the following method (1) or (2) in which the rubber material per se is modified or by any of the following methods (3) to (5) in which the surface or vicinity thereof of the rubber material is modified.
In method (1), powder of a resin such as PE, PTFE, POM or a polyester is mixed in the rubber material (solid lubricant adding method).
In method (2), an oil such as PEG, silicone oil or fluorooil is mixed in the rubber material (bleed method).
In method (3), the surface of rubber molding is covered with a resin (surface covering method).
In method (4), the surface of rubber molding is impregnated with a crosslinking agent and heated so that the crosslinking proceeds in the vicinity of the rubber surface (crosslinking agent infiltrating method). In method (5), a monomer which is compatible with the rubber is infiltrated from the surface into the internal part of the rubber molding and polymerized so that the surface vicinity is cured (surface polymerization curing method; see Japanese Patent Laid-open Publication No. 4(1992)-202239).
In the above solid lubricant adding method (1), for example, the solid lubricant mixed in the rubber material hardly comes out on the surface of the rubber molding, so that the functions such as low function and nonadherence cannot be satisfactorily performed. When, in this solid lubricant adding method, a large amount of solid lubricant is added to the rubber base material in order to improve the above functions of the rubber material surface, the mechanical strength and rubber elasticity of the obtained rubber molding are likely to decrease to thereby deteriorate the follow-up to opposite material, and further the compression set thereof tends to increase even if the above functions can be improved.
In the bleed method (2), the mechanical strength of obtained rubber molding is deficient. Further, the bleeding rate of oil mixed in the rubber material is large, and the lubricity of the rubber molding surface varies in conformity with the bleeding rate. After the completion of the bleeding, phenomena such as rapid increase of the friction coefficient of the rubber molding are encountered. Thus, the rubber molding cannot retain stable lubricity for a prolonged period of time. Still further, there is a problem such that oil having bled from the rubber molding stains the opposite material.
In the surface covering method (3), there is the danger that the mutual adherence of the rubber molding and the surface covering layer which constitute the obtained resin covered molding deteriorates, so that the resin covered molding is unsuitable for practical assembly in apparatus as a sealing member for use in dynamic conditions. Further, the rubber elasticity of the resin covered molding surface tends to lower to thereby cause the follow-up to opposite material to deteriorate.
While in the methods (1) to (3) it is intended to perform the functions such as low friction and nonadherence by furnishing the surface of the rubber material with a substance capable of lowering a surface energy of rubber molding by interposition or covering or by blending the substance wit
REFERENCES:
patent: 5262237 (1993-11-01), Chen et al.
Patent Abstracts of Japan, Publication No. JP-53 003495 A, Jan. 13, 1978.
Patent Abstracts of Japan, Publication No. JP-1 301725 A, Dec. 05, 1989.
Patent Abstracts of Japan, Publication No. JP-4 202239 A, Jul. 23, 1992.
Patent Abstracts of Japan, Publication No. JP-6 53823 (JP-62 146932), Jun. 30, 1987.
Kobayashi Yukio
Sakurai Shinya
Cameron Erma
Nippon Valdua Industries, Ltd.
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