PURPOSE: To obtain carbon black-containing paper having a low content of a residual metal and hygroscopicity and high paper strength and electric conductivity by mixing water floating carbon black as a dispersion in an aqueous solution of a carboxylate surfactant with an aqueous dispersion of fiber, then deactivating the surfactant and forming paper.

CONSTITUTION: Water floating carbon black (e.g. acetylene black) is mixed with an aqueous solution of a carboxylate surfactant (e.g. potassium oleate) to prepare an aqueous dispersion and 0.1N hydrochloric acid is then added thereto while slowly stirring the dispersion. The pH of the dispersion liquid is regulated to about 4-5 and the carboxylate surfactant is deactivated with an acid. The resultant aqueous dispersion is subsequently mixed with an aqueous dispersion of fiber such as cotton linter pulp and stirred with a mixer for 5min. The prepared aqueous dispersion is added to a paper machine having a 150-mesh wire net attached thereto and filled with water to form paper, which is then peeled from the wire net, compressed and dehydrated with a roll and a press and dried with hot air at 130°C to afford carbon black-containing paper, having a high paper strength, a low content of a residual metal and hygroscopicity and good in electric conductivity.