Patent ID: 8435425

Claim:
A polar dispersion composition of an electroconductive carbon black dispersed in a polar dispersion medium using a nonionic dispersant, used to obtain an electroconductive coat by mixing the polar dispersion composition with a binder resin to prepare a coating liquid and subjecting the coating liquid to a coating operation, wherein the electroconductive carbon black has a DBP oil absorption number of 300 to 600 mL/100 g, the nonionic dispersant is a copolymer of a monomer (a) and a monomer (b) with a molar ratio (a)/(b) of 5/95 to 95/5, having a weight-average molecular weight of 1,000 to 1,000,000 and a cloud point in the polar dispersion medium of 30° C. or more and the normal boiling point or less of the polar dispersion medium, where the monomer (a) comprises at least one aromatic vinyl monomer unit as a structure unit, and the monomer (b) is an ethyleneoxide adduct of (meth)acrylic acid alkyl ester, represented by formula (1): where R1 is hydrogen atom or methyl group, R2 is a saturated or unsaturated straight-chain or branched aliphatic hydrocarbon group having 1 to 30 carbon atoms, and n indicates the average number of added moles and is 5 to 50; and 5 to 30 parts by mass of the electroconductive carbon black and 0.1 to 30 parts by mass of the nonionic dispersant are contained in 100 parts by mass of the polar dispersion composition.