Process for bleaching lignocellulose-containing pulps
US5310458A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 1991 |
| Grant date | May 10, 1994 |
| Priority date | — |
| Expiry date | Dec 23, 2011 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C9/163
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
The invention relates to a process for bleaching chemically delignified lignocellulose-containing pulp, to render more efficient a peroxide-containing treatment stage, by treating the pulp with a complexing agent before the peroxide step, so that the trace metal profile of the pulp is altered by the treatment with the complexing agent, in the absence of sulphite, at a pH in the range from 3.1 up to 9.0 and at a temperature in the range from 10.degree. C. up to 100.degree. C., whereupon, in a subsequent step, the treatment with a peroxide-containing substance is carried out at a pH in the range from 7 up to 13, said two-step treatment being carried out at an optional position in the bleaching sequence applied to the pulp.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.