H.sub.2 O.sub.2 /alkaline bleaching of wood pulps
US5296100A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 30, 1991 |
| Grant date | Mar 22, 1994 |
| Priority date | — |
| Expiry date | Apr 30, 2011 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C9/163
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
High-yield lignocellulosic wood pulps are bleached by (i) first pretreating such pulp with a complexing agent for metal ions and next washing the pretreated pulp, and then (ii) bleaching such pretreated/washed pulp with an initial amount of hydrogen peroxide in an alkaline medium, including adding a supplementary bleaching amount of hydrogen peroxide and a supplementary amount of an alkaline agent to the pulp over the course of the bleaching step (ii) without interrupting same, at a point in time when from 60% to 85% of the initial amount of hydrogen peroxide has been consumed, and such supplementary amount of hydrogen peroxide being equal to or less than the initial amount thereof.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.