METHOD OF PRODUCING CELLULOSE FOR MANUFACTURE OF VISCOSE FIBER Russian patent published in 1998 - IPC

FIELD: textile industry. SUBSTANCE: invention relates to producing cellulose from lignocellulose of deciduous and coniferous wood and of one-year plants. Lignocellulose is first treated in cooking pot with saturated steam to achieve prehydrolysis of hemicellulose, and then, at the same pressure, treated with hot secondary lye from preceding cooking step to form sulfate cellulose. In the second step, fresh white lye can be added, if necessary, to neutralize acid reaction product resulting in formation of neutralization lye in the cooking pot. After addition of fresh white lye in amount sufficient to provide delignification in combination (if necessary) with replacement of neutralization lye and adjusting temperature, cellulose material is cooked with or without temperature gradient. When dissolution degree is attained, cooking is terminated by replacing hot secondary lye with cold alkali washing filtrate. Simultaneously, cellulose is freed of remaining lignin destruction products and cellulose is discharged from cooking pot at temperature below 100 C. EFFECT: improved quality of product, reduced cost, and reduced power consumption. 15 cl, 3 dwg