JP2844101B

PURPOSE:To obtain stable development characteristics by incorporating a specified amount of a copolymer having specified repeating units each having quaternary ammonium base and a metal salt or a metal complex salt. CONSTITUTION:The copolymer has the repeating units of the quaternary ammonium bases represented by formula I in which R1 is H or methyl; R2 is alkylene; each of R3 and R4 is alkyl; and Ph is phenyl. The copolymer having said quaternary bases has positive chargeability and effectively functions in suppressing negative chargeability, and it is contained in an amount of 0.01 - 10 wt.% of the total resin, and if < 0.01 wt.%, it cannot suppress the negative charge of the toner, and if > 10 wt.%, the positive charge becomes dominant, and background fog is apt to occur. As a charge controller, the metal salt or metal complex salt is used, thus permitting the development characteristics, such as image density and background fog resistance to be improved.