Method for the alkaline bleaching of pulp with a peroxyacid based oxygen bleaching species using an agglomerated bleach activator
US6569286B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 8, 2001 |
| Grant date | May 27, 2003 |
| Priority date | — |
| Expiry date | Aug 8, 2021 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C9/1036
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
Wood and non-wood pulp is bleached by: a) adding an aliquot of agglomerate from a bulk solids dispensing means, advantageously a hopper, to a dilute solution of hydrogen peroxide which is desirably agitated to keep the agglomerate in suspension, the agglomerate comprising: a bleach activator, advantageously tetraacetyl ethylene diamine (TAED); a peroxide soluble binder, preferably polyvinyl alcohol (PVOH); a dispersing system comprising a wetting agent which is a low foaming and does not discolour on exposure to temperatures of up to 120° C. and optionally a salt, preferably sodium acetate, which is highly soluble in hydrogen peroxide; and sequestrant which may additionally or alternatively be added directly to the hydrogen peroxide; b) allowing the TAED to substantially completely react with the hydrogen peroxide; c) adjusting the pH of the bleach solution by adding alkali, preferably caustic soda; and d) bleaching the pulp by contacting it with the bleaching solution under alkaline conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.