| (19) |
 |
|
(11) |
EP 0 377 981 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
24.06.1992 Bulletin 1992/26 |
| (43) |
Date of publication A2: |
|
18.07.1990 Bulletin 1990/29 |
| (22) |
Date of filing: 18.12.1989 |
|
|
| (84) |
Designated Contracting States: |
|
BE CH DE FR GB LI LU NL SE |
| (30) |
Priority: |
20.12.1988 US 286782
|
| (71) |
Applicant: E.I. DU PONT DE NEMOURS AND COMPANY |
|
Wilmington
Delaware 19898 (US) |
|
| (72) |
Inventors: |
|
- Jayawant, Madhusudan Dattatraya
Hockessin
Delaware 19707 (US)
- D'Souza, Rupert
Concord
California 94521 (US)
- Hsieh, Jeffrey Shaocheng
Marietta
Georgia 30062 (US)
|
| (74) |
Representative: Woodcraft, David Charles et al |
|
BROOKES & MARTIN
High Holborn House
52/54 High Holborn
London, WC1V 6SE
London, WC1V 6SE (GB) |
|
| |
|
| (54) |
Process for improved alkaline oxidative delignification of cellulose pulp |
(57) Treatment of the pulp with sufficient nitrosating agent to provide 0.1 to 1.2 weight
percent active NO
(+) on a dry pulp basis at a pH of 1.7 to 4 and in oxygen environment under high intensity
mixing conditions before an alkaline oxidative stage in a bleach sequence, the nitrosating
agent being a compound that contributes predominantly nitrosonium ions.