Method for improving brightness in bleached pulp
AssigneeNalco Company
InventorsPrasad Y. Duggirala, Sergey M. Shevchenko
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Abstract
The invention is directed towards methods and compositions for processes based on the combination of organic peroxyacids and ammonium salts that preserve and enhance the response to optical brighteners (fluorescent whitening dyes), brightness and improve color of pulp or paper when applied during different stages of the papermaking process are identified. The composition and method improve response to optical brighteners (fluorescent whitening dyes), maintain and/or enhance brightness and enhance the performance of paper products. Used in combination with optical brighteners the described agents produce a synergistic effect not previously identified in the paper process.
Claims9
A method of preparing a bleached pulp material containing an optical brightener having enhanced brightness comprising:
- contacting bleached pulp material with an optical brightener,
- making a paper sheet out of the bleached pulp material, and
- contacting the paper sheet with a composition, the composition comprising an effective amount of an organic peroxy acid in a mixture with ammonium salt at pH 4-9 the ammonium salt having an ammonium portion ionically bonded to an anionic counter ion, the ammonium portion being one selected from the list consisting of methylammonium, dimethylammonium, and urea.
Dependencies are inferred from the claim text.