Sulfite process for making pulp having a tactile softness from hardwood chips

Claim 1

A process for making pulp from hardwood having a tactile sense of softness comprising the steps of: a. Providing hardwood chips having dimensions of from about 0.6 to about 2.5 centimeter; b. Introducing said chips into a digester; c. Removing substantially all the free oxygen from said chips; d. Providing a cooking liquor comprising from about 0.4% to about 3% by weight ammonia and from about 9% to about 14% by weight sulfur dioxide; e. Reacting the lignin in said chips by maintaining the temperature within said digester at less than about 110° C. to form lignin products, wherein said chips are reacted under substantially oxygen-free conditions and substantially all of said chips are immersed in said cooking liquor; f. Increasing the temperature within said digester to from about 140° C. to about 155° C. at a rate of from about 0.75° C. per minute to about 3° C. per minute under substantially oxygen-free conditions; g. Hydrolyzing said lignin reaction products at a temperature of from about 140° C. to 155° C. at a pH of from about 2 to about 3; h. Decreasing rapidly the temperature within said digester; and wherein subsequent to step h, said pulp has a xylan content of between 6% and about 8% by weight on a dry pulp basis, a xylan to mannan weight ratio of between 2.5 and about 3.7 and a glucan content of between about 80% to 92%.