1991 Volume 45 Issue 12 Pages 1392-1399
Acetic acid-water and acetic acid-water-phenols systems were investigated as new solvents for solvent pulping of softwoods.
Todomatsu (Abies sachalinensis Masters) was delignified readily in 70-90% aqueous acetic acid with or without phenols as delignification accelerants at 170-180t. Karamatsu (Larix leptolepis Gord) was very difficult to delignify under the conditions without phenols, and it yielded pulps with Klason lignin content of over 15%. But the delignification of Karamatsu was improved considerably by cooking with aqueous acetic acid containing phenols. More than 85% of p-cresol as the phenols were recovered respectively from the waste liquors of todomatsu and karamatsu.
Strength properties of the pulps were comparable to those of softwood kraft pulps except for tear factor. Acetic acid lignins were separated in greater yields from the waste liquors, but yields of sugar products were lower. Acetic acid lignins of AWL-1 were found to be useful for chemicals because of the higher contents of phenolic hydroxyl groups.
