Inhibition of pulp and paper yellowing using hydroxylamines and other coadditives
US6599326B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 12, 2000 |
| Grant date | Jul 29, 2003 |
| Priority date | — |
| Expiry date | Jan 12, 2020 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21H17/07
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
Chemical pulps or papers, especially kraft pulps or papers, which may still contain traces of lignin, have enhanced resistance to yellowing when they contain an effective stabilizing amount of a N,N-dialkylhydroxylamine, an ester, amide or thio substituted N,N-dialkylhydroxylamine or N,N-dibenzylhydroxylamine or an amminium salt thereof. This performance is often further enhanced by the presence of one or more coadditives selected from the group consisting of the UV absorbers, the polymeric inhibitors, the nitrones, the fluorescent whitening agents and metal chelating agents. Combinations of hydroxylamines or their salts, benzotriazole or benzophenone UV absorbers and a metal chelating agent are particularly effective. N,N-Diethylhydroxylamine and N,N-dibenzylhydroxylamine and their acid salts are surprisingly effective for this purpose.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.