Use of kerosene to improve toner-ink liberation for office paper recycling

A method to disintegrate photocopied or laser printed waste office paper by weak agitation and using kerosene as a toner softening agent was investigated. Under the conventional method using only sodium hydroxide, 3.8% of toner was liberated from paper. This figure increased to 98.1% by using undiluted kerosene, and to 80.1% by using 1% kerosene emulsion. Residual toner particles adhered to only one or a few paper fibers after these kerosene treatments. If residual toner was also included in this figure, toner liberation would reach 100%. The use of surfactants as dispersion agents for kerosene decreased the degree of liberation because it interferes with the softening of toner. It was also confirmed that sodium hydroxide treatment in advance of the kerosene treatment is important to increase toner liberation.