PRODUCTION OF NEW GRADES OF MECHANICAL PULP

Atmospheric co-refining, without chemical addition, of three types of wastepaper (old newspaper, telephone directory and xerographic ledger) with a softwood chemithermo-mechanical pulp was conducted using a Sun ds Defibrator (D300 refiner to produce a new grade of mechanical pulp for the manufacture of newsprint without the use of expensive deinking equipments and chemicals. The results indicated that up to about 50% of wastepaper may be incorporated into a CTMP furnish without a signif icant loss of papermaking potential.