PURPOSE: To stabilize the quantity of frictional electric charge and to make uniform the distribution of frictional electric charge by incorporating diorganotin borate obtd. by allowing diorganotin oxide to react with equimolar amt. of boric acid until the amt. (mole) of dehydrated water exceeds the amt. of boric acid (mole) into a toner.

CONSTITUTION: Diorganotin borate obtd. by allowing diorganotin oxide to react with equimolar amt. of boric acid until the amt. of dehydrated water exceeds the amt. (mole) of boric acid is incorporated into a toner as a positive charge regulating agent. The dehydration reaction product of diorganotin oxide with boric acid is stable thermally and for the lapse of time and has quite small hygroscopic property, particularly, the diorganotin borate obtd. by the process of this invention has further improved stability for the environmental change and durability of positive frictional electric charge to be caused by a carrier or a sleeve, etc.