Method for reducing alkaline darkening of mechanical pulp containing a calcium carbonate filler
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United States of America Patent
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Feb 14, 2006
Grant Date -
May 23, 2002
app pub date -
Nov 27, 2001
filing date -
Oct 28, 1998
priority date (Note) -
Expired
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Abstract
A method is disclosed for reducing or inhibiting alkaline darkening of mechanical pulp caused by the presence of calcium carbonate filler during production; the method comprises adding a sulfite, or sulfur-containing reducing agent, especially a sulfite to the mechanical pulp and the filler; the method is usefully applied in the production of mechanical pulp and paper in which calcium carbonate is used as a filler and also in the production of paper at neutral or mildly alkaline conditions.
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