Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-09-04
2004-05-18
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S331700, C525S387000, C524S445000, C524S525000, C526S335000, C138S126000, C428S036800
Reexamination Certificate
active
06737480
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a low-contaminative hose that permits a fluid to be passed therethrough with an absolutely minimal level of fluid contamination, and further to a rubber composition for use in producing such a hose.
DESCRIPTION OF THE ART
Due to the problems with environmental pollution, the exhaustion of petroleum resources and the like, an impetus has been gathered in recent years to develop fuel cell-powered vehicles. A fuel cell is designed to receive, via supply pipes, a fuel gas typified by hydrogen or methanol, source of oxygen typified by air, and a cooling liquid typified by water or glycol. Thus, in the fuel cell, hydrogen component of the above fuel gas is allowed to react with oxygen component of the above air, thereby generating electrical energy. Unreacted components of the above fuel gas and unreacted air are released from the fuel cell through their respective exhaust pipes and then put back into their respective supply pipes. The above cooling liquid, which is being circulated in the fuel cell, is released through its exhaust pipe, followed by cooling and returns to its supply pipe.
A single cell in the fuel cell is generally structured with electrodes fitted thereto, which electrodes are formed by coating a catalyst such as platinum or the like on both sides of a plate-like electrolyte. The two electrodes are further connected to externally disposed electrical conductors. Electricity generation is performed with the fuel gas supplied to one such electrode, i.e., a negative pole, and with the air supplied to the other, i.e., a positive pole. More specifically, the fuel gas is decomposed by the action of the catalyst into hydrogen ions, i.e., protons, and electrons at the negative pole so that the hydrogen ions migrate to the positive pole after passage through the above-mentioned electrolyte, and the electrons migrate to the positive pole after passage through the above-mentioned external conductors. At the positive pole, the oxygen gas contained in the air is catalytically reacted with the hydrogen ions and electrons that have been migrated to that pole as stated above, whereby water is produced. Such a single cell structure acts as a fuel cell because an electric current flows upon migration of the above electrons.
However, in situations where ion extraction occurs from transport pipelines including the above supply pipes, exhaust pipes and the like, fluids such as a fuel gas and the like passing through the pipelines become mixed with and contaminated by the extracted ions. This causes contamination of the electrolyte, catalyst and the like in the above-described fuel cell, thus causing failure in the proper migration of hydrogen ions, decomposition of fuel gas and production of water during electricity generation. The fuel cell, therefore, suffers from poor efficiency in electricity generation and a considerable decline in output.
As another serious problem resulting from the ion extraction from each transport pipe, the fluid itself running through the pipeline becomes easily electrically conductive, and therefore, the fuel cell is liable to produce electrical leakage outwardly through the fluid. This electrical leakage is responsible for inefficient electricity generation in the fuel cell and also for generating hazardous electrical shocks to human beings.
Similar consequences occur, in addition to the transport pipes used in a fuel cell, in transport pipes for cooling liquids used in super computers, as well as in transport pipes for membrane cleaning liquids used in analytical instruments, and in the transport pipes for chip or wafer cleaning liquids used in semiconductor production. Namely, in the case of ion extraction arising from a cooling liquid-transport pipe used in such a super computer, the cooling liquid flowing through that pipe tends to become easily electrically conductive due to the extracted ions. Thus, the super computer is likely to produce outward electrical leakage, or produce improper operating signals. Furthermore, in the case of ion extraction arising from a membrane cleaning liquid-transport pipe used in such an analytical instrument, the membrane tends to be contaminated by the extracted ions, thus failing to ensure accurate analysis. And furthermore, in the case of ion extraction arising from a chip cleaning liquid-transport pipe used in semiconductor production, the semiconductor chips tend to be contaminated by the extracted ions, thereby frequently producing defective chips.
From the standpoint of good assembly working, it has been demanded that each such transport pipes be formed from a flexible material, that is, a hose.
SUMMARY OF THE INVENTION
The present inventors have made intensive studies in order to prevent a fluid running through a hose from being contaminated by the hose itself. In the studies, an approach has been centered on using at least one rubber selected from among an ethylene-propylene-diene terpolymer, an ethylene-propylene copolymer and a silicone rubber, and it has been found that when one such rubber is vulcanized using a peroxide as a vulcanizing agent, the use of a vulcanization accelerator such as a metal oxide or a metal hydroxide can be omitted, which accelerator is required for a rubber to be sulfur-vulcanized, and that the resultant hose is less likely to extract ions, which are eventually mixed in the fluid being passed through the hose. From further studies, it has also been found that when the above-noted rubber is subjected to peroxide vulcanization in the presence of a filler having a laminar crystal structure, a hose is formed which can more reliably alleviate ion extraction with respect to a fluid passing through the hose. These findings have led to the present invention. Here, the reason why such a filler with a laminar crystal structure is effective in making the hose much more resistant to ion extraction would presumably be attributable to the fact that the ions, even if extracted, are brought into an entrapped condition between the layers arranged to constitute the above-mentioned laminar crystal structure.
Accordingly, one object of the present invention is to provide a low-contaminative hose that permits a fluid to be passed therethrough at an absolutely minimal level of fluid contamination. Another object of the invention is to provide a rubber composition used in producing such a hose.
According to one aspect of the subject invention, a low-contaminative hose is provided which includes as essential components
(A) at least one rubber selected from the group consisting of an ethylene-propylene-diene terpolymer, an ethylene-propylene copolymer and a silicone rubber;
(B) a peroxide vulcanizing agent; and
(C) a filler having a laminar crystal structure.
According to another aspect of the present invention, a rubber composition for use in producing such a low-contaminative hose is provided which includes as essential components,
(A) at least one rubber selected from the group consisting of an ethylene-propylene-diene terpolymer, an ethylene-propylene copolymer and a silicone rubber;
(B) a peroxide vulcanizing agent; and
(C) a filler having a laminar crystal structure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be described in greater detail and with regard to preferred embodiments.
One embodiment of the low-contaminative hose according to the invention can be achieved using a specific rubber composition. This rubber composition includes, as essential components, a selected rubber (component A), a peroxide vulcanizing agent (component B) and a filler having a laminar crystal structure (component C).
The selected rubber (component A) is chosen from an ethylene-propylene-diene terpolymer (hereinafter denoted by “EPDM”), an ethylene-propylene copolymer (hereinafter denoted by “EPM”) and a silicone rubber. These rubbers may be used singly, or two or three rubbers may be used in combination. EPDM is not specifically limited so long as it can be suitably used as a base material for the above-mentioned rubber composition.
Ikeda Hidehito
Ikemoto Ayumu
Okado Yoshio
Armstrong Kratz Quintos Hanson & Brooks, LLP
Hu Henry S.
Tokai Rubber Industries Ltd.
Wu David W.
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