Method of manufacturing bleached chemimechanical and semichemical fibre pulp by means of a one-stage impregnation process
US4756799A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Mar 12, 1986 |
| Grant date | Jul 12, 1988 |
| Priority date | — |
| Expiry date | Mar 12, 2006 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21B1/16
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
In accordance with the invention a chemimechanical pulp is produced from lignocellulosic material, for example wood chips, by subjecting the material to a process in which it is steamed, impregnated with alkali and peroxide, drained, pre-heated, refined and bleached. The material is impregnated in a single stage with a solution containing alkali and peroxide. Subsequent to passing an intermediate drainage and reaction stage, the material is pre-heated to a temperature of from about 50.degree. C., but not above 100.degree. C. The material is then refined in one or two stages. The material can be impregnated by immersing the same in the impregnating solution for a period of up to 20 minutes at a temperature of 15.degree.-60.degree. C., or by compressing the material in a screw press and permitting the compressed material to expand in the impregnating solution. The optimal brightness for a given peroxide charge is achieved by a balanced division of the peroxide charge between the chip impregnating stage and the bleaching stage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.