To obtain a conductive resin composition which can give a molding having a high conductivity, excellent electromagnetic shielding properties, a high rigidity, and a reduced tendency to warp by incorporating a thermoplastic resin such as a polyamide resin with a carbon fiber and an expandable graphite.
This composition comprises 100 pts.wt. thermoplastic resin such as a polyamide resin, 5-40 pts.wt. carbon fiber having a fiber length of 40 μm to 7 mm and a fiber diameter of 6-8 μm, 5-60 pts.wt. expandable graphite having a size of 1-100 μm, and at most 50 pts.wt. bromine-containing flame retardant such as brominated polystyrene or a red phosphor flame retardant. The polyamide resin is desirably one having a relative viscosity of 1.4-4.0 (in 96% sulfuric acid in a concentration of 1 g/dl at 25°C) and a crystalline polyamide/noncrystalline polyamide ratio of 50/50 to 95/5 by weight. The expandable graphite used is one obtained by treating a natural scaly graphite with e.g. a mixed acid such as concentrated sulfuric acid/concentrated nitric acid, washing and dehydrating the treated graphite and expanding the obtained product at 800-1,200°C at an expansion ratio of 10-200 on the basis of the volume of the starting graphite and having a size of 1-100 μm.
KAMIYA KENJI
NEGI YUKINARI
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