抄録
In order to produce bleached pulps in high yields from softwoods, the behaviors of cooking and bleaching was investigated. In the sulfite-formaldehyde-anthraquinone (SFQ) cooking of akamatsu (Pinus densiflora), the high-yielded chemical pulp with 49.5 of kappa number was produced in a 54.5% yield. However, the rejects yield was much higher than that of the ezomatsu (Picea yezoensis) wood pulping. Akamatsu wood was shown to be appropriate for polysulfide-anthraquinone (PS-AQ) pulping but be inappropriate for the SFQ method. Although kraft pulp could be bleached to high brightness in the nitrous acid pretreatment and hydrogen peroxide followed by chlorine dioxide and peroxide bleaching (NP1DP2) process, the brightness of the SFQ pulp did not increase very much. In the ozone pretreatment and sulfite delignification followed by ozone and peroxide bleaching (ZS-Z1P) process, the SFQ pulp could be bleached to high brightness with acceptable viscosity. However, the yield decreased largely. The AEOPHDP process standing for the acid pretreatment for the manganese reduction, oxygen-pressurized hydrogen peroxide, hypochlorite, chlorine dioxide, and peroxide bleaching process was shown to be effective for bleaching of PS-AQ pulp to high brightness with acceptable viscosity, but be ineffective for bleaching of SFQ pulp.
