Process for the production of viscose pulp
US5676795A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jul 13, 1995 |
| Grant date | Oct 14, 1997 |
| Priority date | — |
| Expiry date | Jul 13, 2015 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C1/02
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
The present invention relates to a process for producing viscose pulp from lignocelluloses, such as hardwood, softwood or annual plants, in which process the lignocellulose is treated in a digester at first with saturated steam to prehydrolyze hemicelluloses and subsequently, without flashing, with hot black liquor (HSL) of a preceding sulfate pulp digestion as well as, if desired, under addition of fresh white liquor (WL) to neutralize the acidic reaction products formed, neutralization liquor (NL) thus being formed in the digester. Upon addition of the amount of alkali required for delignification in the form of fresh white liquor (WL), if desired, in combination with a displacement of neutralization liquor (NL) and temperature adjustment, digestion then will take place with or without temperature gradient. When reaching the desired degree of digestion, digestion is terminated by displacement of the hot black liquor (HSL) with cold alkaline washing filtrate (WF), at the same time the pulp is freed from still adhering lignin degradation products, and the thus obtained pulp is discharged from the digester at a temperature of below 100.degree. C.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.