International Paper Company

Kent Witherspoon

Caifang F Yin

This invention relates to an improved bleaching process for bleaching pulp comprising at least one bleaching stage which comprises treating a hardwood pulp with a bleaching agent comprising ClOin the presence of a weak base such as, for example, Mg(OH)preferably at pH from about 3.5 to about 6.5. The invention is also relates a bleaching process for bleaching pulp having two or more bleaching stages, at least one of which and preferably two of which comprises treating a hardwood pulp with a bleaching agent comprising ClOin the presence of a weak base such as, for example, Mg(OH)preferably at pH from about 3.5 to about 6.5.

Process of bleaching hardwood pulps in a D1 or D2 stage in a presence of a weak base

This invention relates to an improved bleaching process for bleaching pulp comprising at least one bleaching stage which comprises treating a softwood pulp with a bleaching agent comprising ClOin the presence of a weak base such as, for example, Mg(OH)preferably at pH from about 3.5 to about 6.5. The invention is also relates a bleaching process for bleaching pulp having two or more bleaching stages, at least one of which and preferably two of which comprises treating a softwood pulp with a bleaching agent comprising ClOin the presence of a weak base such as, for example, Mg(OH)preferably at pH from about 3.5 to about 6.5.

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Killen, AL, United States of America

Kent Witherspoon