Method for treating bleached lignin containing cellulose pulp by reducing .alpha.-carbonyl and .gamma.-carbonyl groups and converting short-wave quanta to long-wave light quanta
US5035772A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 28, 1989 |
| Grant date | Jul 30, 1991 |
| Priority date | — |
| Expiry date | Sep 28, 2009 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21H11/20
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A method for treating lignin containing pulp, subsequent to being bleached by: PA0 a) always treated with at least one chemical, which chemically reduces .alpha.-carbonyl and .gamma.-carbonyl groups in the lignin; and in at least one further step is PA0 b) treated with at least one chemical, which will block the phenolic hydroxyl groups of the lignin and/or PA0 c) supplied with at least one chemical, which will convert short-wave light quanta to long-wave light quanta. According to a preferred embodiment of the invention cellulose pulp is subjected to all of the above treatment processes, i.e. a)+b)+c) and is washed after the two initial treatment stages. The method solves the problem of yellowing of lignin containing pulps, e.g. high yield pulp.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.