Method of peroxide bleaching of pulp pretreated with a sequestering agent then with a sulphite and reducing agent
US5143581A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 6, 1991 |
| Grant date | Sep 1, 1992 |
| Priority date | — |
| Expiry date | Mar 6, 2011 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C9/163
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A process for the manufacture of high-yield pulps bleached with the aid of hydrogen peroxide in alkaline medium, which consists in subjecting the pulp to be bleached successively to: PA0 (a) a pretreatment with the aid of a sequestering agent for metal ions, followed by a washing operation, PA0 (b) a treatment with sulphite and a reducing agent which is more electronegative than the sulphite ion, which act together and in a medium of initial pH between 7 and 12.5, followed by a washing operation to remove the sulphite ions and the reducing agent, and PA0 (c) to a bleaching treatment with the aid of hydrogen peroxide in alkaline medium in the presence of a quantity of silicate of between 0% and 1%.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.