Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-12-18
2001-08-14
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S496000
Reexamination Certificate
active
06274665
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a molding composition for sealing carbon dioxide, and a molded composition having an excellent sealing property to be able to be used for sealing carbon dioxide. Also, the present invention relates to a sealing device to provide a seal between relatively movable portions on one of which a portion of the sealing device is held, sealingly contacting with another movable portion at a seal lip of the sealing device.
2. Related Art
Conventionally, Freon gas has been used in almost all automobile air-conditioners, refrigerators or the like as a coolant. But from the point of view of environment disruption (the depletion of the ozone layer, global warming or the like), new coolants other than Freon gas have been recently extensively studied. Carbon dioxide is considered to be one of a most hopeful next generation of coolants. In the case of conventional Freon gas, sealing Materials such as hydrogenated NBR, EPDM (Ethylene-Propylene-Diene terpolymer) or the like have been used as sealing materials, but these materials have some defects such as swelling and blistering which occurs in the sealing materials when contacting carbon dioxide. These undesirable phenomena tend to cause the sealing device to be unusable. Particularly, the addition of a non-reinforcing filler with a large particle size such as mica or graphite for aiming to decrease in gas permeability of these rubber materials makes blisters occur easily, resulting in an unusable condition as a molded composition for sealing carbon dioxide.
On the other hand, there are some materials having a property of low gas permeability to carbon dioxide, such as vinylidene fluoride resin or the like. But these materials have a defect in processability or flexibility which rubber materials usually have. When these resin like materials are used as sealing materials—especially such a sealing means as a rotating shaft seal, a reciprocating shaft seal or the like, response to an axis to be sealed is slow when the axis is biased. This phenomena causes a microscopical gap between the seal lip and the axis and then to cause leakage of a sealing medium. In addition, when the sealing material made of vinylidene fluoride resin is assembled with an axis having splines (grooves made in the direction of the axis), a scratch is easy to occur by the splines and the scratch may not allow to keep optimum sealing performance.
There is a fluoro rubber which contains vinylidene fluoride. This type of fluoro rubber has excellent flexibility but the anti-permeability to carbon dioxide is not good.
Furthermore, it has been described in the publication of Japanese patent Tokkai Sho 59-40066 (1984), Tokkai Hei 6-25500 (1994), Tokko Hei 3-2197 (1991), Tokko Hei 3-59937 (1991) and Tokko Hei 7-68430 (1995) that a fluoro thermoplastic elastomer can be used for a molding material for a sealing composition resistant to lubricant. However, in these descriptions, MT carbon black (particle diameter: 201 to 500 nm) which is commonly used as a reinforcing fillet for fluoro rubbers has been used as it is.
When fluoro thermoplastic elastomer containing MT carbon black is used for sealing devices for sealing carbon dioxide, both permeability of and swelling due to exposure to carbon dioxide is large, and a blister phenomena can be seen so that these compositions cannot be safely used in the seal for sealing carbon dioxide.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a molding composition being composed of a fluoro rubber type thermoplastic elastomer and a reinforcing filler, having an excellent anti-carbon dioxide gas permeability and anti-swelling property to carbon dioxide gas, and especially having an excellent anti-blistering property to carbon dioxide gas.
Another object of the present invention is to provide a molded sealing composition having excellent sealing properties to carbon dioxide as well as having excellent rubber like responsive properties.
Another object of the present invention is to provide a sealing device having excellent sealing properties to carbon dioxide as well as having excellent rubber like responsive properties to a sliding portion to be sealed.
The object of the present invention can be achieved by using a reinforcing filler with a particle size of 100 nm or smaller in a fluoro thermoplastic elastomer, preferably by using the reinforcing filler and a non-reinforcing filler in combination. Another object of the present invention can be achieved by molding the fluoro thermoplastic elastomer with or without other rubber materials into various sealing products to seal carbon dioxide. Another object of the present invention can be achieved by placing a fluoro thermoplastic elastomer composition having reinforcing filler of not larger than 100 nm in particle diameter onto a surface of fluoro rubber sealing materials to form a sealing device.
REFERENCES:
patent: 5371143 (1994-12-01), Novak et al.
Abstract of Japanese No. 59-40066, Mar. 5, 1984, Masayasu et al, “Sealing Material Having Resistance to Lubricating Oil”.
Abstract of Japanese No. 6-25500, Feb. 1, 1994, Yoshihiro, “New Fluororubber Composition”.
Abstract of Japanese No. 3-2197, Apr. 5, 1984, Masayasu et al, “Paint Composition”.
Abstract of Japanese No. 3-59937, Feb. 13, 1985, Masaharu et al, “Fluorine-Containing Thermoplastic Rubber . . . ”.
Abstract of Japanese No. 7-68430, Mar. 27, 1991, Masanaga, “Thermoplastic Elastomer Composition, Its Molding . . . ”.
Kobayashi Osamu
Minagawa Hironori
Ohta Takashi
Ono Shigeyuki
Tokumitsu Hideyuki
Cain Edward J.
Jacobson & Holman PLLC
NOK Corporation
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