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
2001-07-30
2003-09-30
Seidleck, James J. (Department: 1711)
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...
C524S495000, C524S496000
Reexamination Certificate
active
06627689
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a curable resin composition. More specifically, the present invention relates to an electroconductive curable resin composition and a cured (or hardened) product thereof having not only excellent electroconductivity but also an excellent heat-radiating property.
BACKGROUND ART
The pace of recent technological innovations in the electronics industry, etc., is remarkable, and materials technology supporting the electronics industry is also making rapid progress. The same applies to the development of polymer materials and a large number of novel or high performance polymer materials have been newly developed and have individually expanded their range of uses in a steady manner.
The principal properties required for the polymer materials in the field of electronics are formability, heat resistance, durability, electrical characteristics (e.g., high insulation, high electroconductivity), corrosion resistance, heat-radiating property and the like, though these properties may vary depending on the products or uses. In many cases, for such purposes, there are used thermosetting resins represented by epoxy resins, phenolic resins, etc., or various engineering plastics represented by polyimides, polycarbonates, polyphenylene oxides and liquid crystal polymers, etc.
The demand for a material comprehensively having all of the above-mentioned various performances is of course strong, but great difficulties are present for realizing such a polymer in view of the techniques to be used therefor, and often disadvantageous results appear in view of the cost thereof. One of the technical requirements is to develop a polymer material having electroconductivity (particularly, high electroconductivity such that the volume resistivity is 1 &OHgr;cm or less) and at the same time a having heat-radiating property and heat resistance. It is an object of the present invention to develop such a material. More specific examples of the above material may include a highly electroconductive composition for use in various members to be used in the field of batteries, such as separators for fuel cells using hydrogen, alcohol or the like as the fuel therefor.
Many studies have been made in the past on highly electroconductive compositions comprising a carbonaceous material and a thermosetting resin composition. For example, a combination of graphite and a phenolic resin is disclosed in JP-B-50-11355 (the term “JP-B” as used herein means an “examined Japanese patent publication”) and JP-A-59-213610 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). Also, in the case of using an epoxy resin and an unsaturated polyester resin as base resins, a plurality of techniques have been disclosed.
Further, to prepare a curable resin composition where a higher electroconductivity is required, there is known a method of forming (or shaping) the curable resin composition, and then heating so as to carbonize and graphitize the resultant formed product (see, for example, JP-A-8-222241).
When a curable resin composition containing normal graphite powder is used, the amount of graphite powder added must be greatly increased so as to provide the same electroconductivity as the cured product according to the present invention. As a result, when such a composition containing normal graphite powder is used, not only the specific gravity of the formed product disadvantageously is increased but also the formability thereof is deteriorated at the time of the formation process such as compression molding, transfer molding or injection molding. Further, in the case of a composite material comprising a combination of a resin and normal graphite powder, a cured product having a contact resistance of 2×10
−2
&OHgr;cm
2
or less could not be obtained.
If the production process includes a step of heating the formed product to a high temperature of 1,000° C. to 3,000° C. for a long time for the purpose of obtaining a high electroconductivity, there arises a problem that the production takes a long time and that the production process becomes complicated so as to increase the production cost.
DISCLOSURE OF INVENTION
The present invention has been made under these circumstances and a main object of the present invention is to provide an electroconductive curable resin composition which is capable of providing a cured product having an excellent electroconductivity, a high heat resistance, a good heat-radiating property and a superior polymer processability, even when the curable resin composition contains a relatively small amount of electroconductive filler charged therein. This object also includes providing a cured product of such a electroconductive curable resin and a formed product using the curable resin composition.
Under these circumstances, the present inventors have made extensive investigations to develop an electroconductive curable resin composition comprising, as main starting materials, a graphite powder and a curable resin or a monomer composition therefor (if desired, further containing an initiator or the like), which can provide a cured product having an excellent electroconductivity, a high heat resistance and a good heat-radiating property. As a result, an electroconductive curable resin composition and a cured product achieving the object of the present invention have been accomplished by the combination of a specific graphite containing boron with a curable resin.
More specifically, the present invention relates to an electroconductive curable resin composition, a cured product thereof and a formed product using the curable resin composition, which typically include the following embodiments (1) to (17).
(1) An electroconductive curable resin composition comprising (A) a graphite powder containing boron in the graphite crystal, and (B) a curable resin and/or a curable resin composition, at a ratio of 20 to 99.9:80 to 0.1 in terms of the mass ratio of the component (A) to component (B) provided that the sum of the mass ratios of the components (A), (B) and (C) is 100.
(2) An electroconductive curable resin composition comprising (A) a graphite powder containing boron in the graphite crystal, (B) a curable resin and/or a curable resin composition, and (C) vapor-phase process carbon fiber having a fiber diameter of 0.05-10 &mgr;m and a fiber length of 1-500 &mgr;m, and/or carbon nanotube having a fiber diameter of 0.5-100 nm and a fiber length of 0.01-10 &mgr;m.
(3) An electroconductive curable resin composition as described in the above item (2), wherein the mass ratio of the sum of the components (A) and (C) to the component (B), i.e., the mass ratio (A+C:B) is 20 to 99.9:80 to 0.1 provided that the sum of the mass ratios of the components (A), (B) and (C) is 100.
(4) An electroconductive curable resin composition as described in the above item (2) or (3), wherein the mass ratio of the component (A) to the component (C) is 60 to 99.9:40 to 0.1 provided that the sum of the mass ratios of the components provided that the sum of the mass ratios of the components (A) and (c) is 100.
(5) An electroconductive curable resin composition as described in any one of the above items (1) to (4), wherein the powder electric resistivity in the right angle direction of the graphite powder as the component (A) is 0.06 &OHgr;cm or less with respect to the applied pressure direction, in a state where a pressure is applied to the graphite powder so as to provide a bulk density of the graphite powder of 1.5 g/cm
3
.
(6) An electroconductive curable resin composition as described in any one of the above items (1) to (5), wherein the component (A) has an average particle size of 5 to 80 &mgr;m.
(7) An electroconductive curable resin composition as described in any one of the above items (1) to (6), wherein the component (A) is a graphite powder having a specific surface area of 3 m
2
/g or less, an aspect ratio of 6 or less, a tapping bulk density of 0.8 g/cm
3
or more and a lattice spacing (Co value) of 6.745 Å or less.
(8) An ele
Iino Tadashi
Imaizumi Mitsuhiro
Rajguru U. K.
Seidleck James J.
Showa Denko K.K.
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