METHOD FOR REDUCING BRIGHTNESS REVERSION IN LIGNIN-CONTAINING PULPS AND ARTICLE OF MANUFACTURE THEREOF

A method and article of manufacture thereof is provided for reducing brightness reversion in bleached lignin-containing pulps or newsprint by the treatment of the bleached lignin-containing pulp or newsprint with a compound which donates a hydrogen atom to a photo-excited group or free radical more...

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Bibliographische Detailangaben
Hauptverfasser:	FRANCIS, RAYMOND C, DENCE, CARLTON W, ALEXANDER, THOMAS C
Format:	Patent
Sprache:	eng
Schlagworte:	APPARATUS THEREFOR IMPREGNATING OR COATING OF PAPER PAPER NOT OTHERWISE PROVIDED FOR PAPER-MAKING PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D PRODUCTION OF CELLULOSE PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCESFROM CELLULOSE-CONTAINING MATERIALS PULP COMPOSITIONS REGENERATION OF PULPING LIQUORS TEXTILES TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G
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Beschreibung
Zusammenfassung:	A method and article of manufacture thereof is provided for reducing brightness reversion in bleached lignin-containing pulps or newsprint by the treatment of the bleached lignin-containing pulp or newsprint with a compound which donates a hydrogen atom to a photo-excited group or free radical more easily than does the lignin contained in the treated pulp. The hydrogen donating compounds include compounds with certain formyl functionality, including formate salts such as sodium, magnesium and calcium formate, formamides, formic acid esters, and formylurea. In one embodiment, calcium carbonate is added to enhance the activity of the formyl compound. The further addition of a trace amount of superoxide anion quencher such as copper sulfate or ascorbic acid is also provided to still further enhance the activity of the formyl compound, especially formate salts.