Inhibition of pulp and paper yellowing using nitroxides, hydroxylamines and other coadditives
US6254724A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 20, 1998 |
| Grant date | Jul 3, 2001 |
| Priority date | — |
| Expiry date | Jul 20, 2018 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21H21/143
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Pulps or papers, especially chemimechanical or thermomechanical pulps or papers, which still contain lignin, have enhanced resistance to yellowing when they contain an effective stabilizing amount of a hindered amine compound which preferably is a nitroxide, a hydroxylamine or an ammonium 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, metal chelating agents, sulfur containing stabilizers, metal salts and diene compounds. Combinations of nitroxides, hydroxylamines or their salts, benzotriazole or benzophenone UV absorbers and a metal chelating agent are particularly effective. Selected derivatives of 1-oxyl-2,2,6,6-tetramethyl-piperidin-4-ol and selected hydroxylamine salts are novel compounds and are surprisingly effective for this purpose.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.