Electricity: circuit makers and breakers – Special application – Liquid or moisture responsive
Reexamination Certificate
2002-12-30
2004-04-20
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Special application
Liquid or moisture responsive
C340S605000
Reexamination Certificate
active
06723932
ABSTRACT:
TECHNICAL FIELD
This invention relates to a water-immersed switch which uses a polymer material containing acrylonitrile and at least one of styrene and/or a conjugated diene, as constituent units, or a waste material thereof, and which, subject to inflow of an inductive fluid, allows for electrical conduction across plural electrodes and for maintaining the state of the electrical conduction for a prolonged time. This invention also relates to a method for the preparation of the water-immersed switch.
The water-immersed electrical switch, which may also be called a water-flushed electrical switch, is such a switch which does not conduct the electricity in the absence of a dielectric liquid, such as water, and which conducts the electricity in the presence of the dielectric liquid.
In the present specification, the copolymer material containing (a) acrylonitrile and (b) at least one of styrene and/or a conjugated diene, as constituent units, is sometimes abbreviated to a ‘copolymer’. A modified copolymer comprised of the copolymer into which have been introduced acidic groups is sometimes abbreviated to ‘a modified copolymer’.
BACKGROUND OF THE INVENTION
Among the resins containing acrylonitrile and styrene or a conjugated diene as constituent units, there are polystyrene based resins, exemplified by an ABS (acrylonitrile-butadiene-styrene) resin, a SAN (styrene-acrylonitrile) resin or an AAS (acrylonitrile-acrylate-butadiene) resins, and synthetic rubber, such as NBR (acrylonitrile-butadiene) rubber. These resins are relatively inexpensive and, in particular, the polystyrene based resins are superior in toughness, dimensional stability or workability, and hence are used in abundant quantities as a resin material for covers or casings for variegated use, and for chassis or variegated component materials for electrical equipment or automobiles. The synthetic rubber is also used in abundant quantities as tubing, hoses or as variegated shock-absorbing materials.
Recently, the production volume of the products employing the abovementioned resin materials is increasing. In keeping pace therewith, the amount of waste materials derived from these materials tends to be increased, such that, in conjunction with the general interest in maintenance of the global environment, there is an increasing need for effective utilization of the waste materials derived from the above-mentioned resin materials.
Under such situation, the above-mentioned resin materials are expected to be re-used in an enlarged range of application, such that there is raised a demand for modification of the resin materials to higher added value products.
Meanwhile, the polymer-based waste materials are disposed of roughly by three types of techniques, namely land-filling, incineration and re-melting. Of these, land-filling and incineration account for approximately 90% of the total amount of disposal of the waste material, meaning that most of the waste material is not re-used.
As the method of recycling the polymer waste material, such a method of melting by heating and re-molding is routinely used, insofar as the thermoplastic resin is concerned. In this case, a lot of problems are presented, such as thermal deterioration, for example the lowering of the molecular weight or resin oxidation, admixture of foreign matter, such as dust and dirt, or admixture of resins containing various colorants which leads to the necessity of color matching. That is, in recycling polymer waste materials by heating or melting, processing techniques or costs pose serious impediments.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electrical switch in which a polymer material containing acrylonitrile on one hand and styrene and/or a conjugated diene on the other hand or its waste material may be used effectively as a material of a higher added value, and a method for producing the electrical switch.
The present inventors have conducted eager searches towards accomplishing the above object, and have completed a water-immersed electrical switch comprised of the modified product and plural electrically conductive electrodes, which electrodes are electrically connected to each other on inflow of a dielectric liquid. The modified product is made up by a polymer material, preferably a used resin, containing a preset amount of acrylonitrile on one hand and at least one of styrene and/or a conjugated diene on the other band, as constituent units, and by acidic groups introduced into the modified product.
Specifically, the water-immersed electrical switch according to the present invention uses a polymer material, preferably a used resin, containing a preset amount of acrylonitrile and styrene or a conjugated diene, and modifies it to form a modified copolymer or a hydrophilic gel by introducing acidic groups at least into the styrene or conjugated diene part of the polymer material. The hydrophilic gel is then dehydrated, if so desired, and is combined with plural electrically conductive electrodes. In the water-immersed electrical switch according to the present invention, when a dielectric liquid flows to or around the hydrophilic gel, the latter is swollen to become an ion-conductive electrolyte to produce electrical conductivity across the electrically conductive electrodes. This electrical conductivity may be maintained for an extended period of time.
The method for producing the water-immersed electrical switch according to the present invention combines a modified copolymer, comprised of a polymer material, preferably a used resin, containing, as constituent units, a preset amount of acrylonitrile on one hand and at least one of styrene and/or a conjugated diene on the other hand, and acidic groups, introduced thereto, with plural electrically conductive electrodes. Specifically, the method of the present invention includes acid-processing a polymer material, or a used resin, comprised of a polymer material, preferably a used resin, containing, as constituent units, a preset amount of acrylonitrile on one hand and at least one of styrene and/or a conjugated diene on the other hand, to produce a modified product, dehydrating the resulting product, if so desired, and combining the modified product with a plurality of electrically conductive electrodes to produce a water-immersed electrical switch, in which, when the dielectric liquid flows to the switch, electrical conductivity is produced across the electrically conductive electrodes.
According to the present invention, the copolymer preferably contains 5 to 80 mol % of acrylonitrile units. The copolymer also preferably contains 20 to 95 mol % of the constituent unit of at least one of styrene and/or a conjugated diene.
The copolymer is at least one selected from the group consisting of ABS (acrylonitrile-butadiene-styrene) resin, SAN (styrene-acrylonitrile) resin and NBR (acrylonitrile-butadiene) rubber.
The copolymer further contains an inorganic pigment.
The inorganic pigment is carbon black and/or titanium oxide.
The inorganic pigment is preferably contained in an amount of 0.01 to 5 wt % based on the weight of the copolymer (dry weight).
The acidic group in the modified copolymer is at least one selected from the group consisting of a sulfo group, —PO(OH)
2
and —CH
2
PO(OH)
2
.
The acidic group in the modified copolymer is a sulfo group.
The acidic group in the modified copolymer is preferably contained in an amount of 5 to 95 mol % based on the total weight of the units in the modified copolymer.
The water-immersed electrical switch according to the present invention includes a modified copolymer, and a plurality of electrically conductive electrodes. The modified copolymer is a used resin into which acidic groups are introduced. The used resin is a modified copolymer containing acrylonitrile and at least one of styrene and/or a conjugated diene, as constituent units, and acidic groups introduced into the modified copolymer, with the used resin having been molded for use in specified application.
The copolymer contains 5 to 80 mol % of acrylonitrile
Inagaki Yasuhito
Noguchi Tsutomu
Ohki Hiroshi
Watanabe Haruo
Friedhofer Michael
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
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