Softwood kraft fiber having improved whiteness and brightness and methods of making and using the same technical field
AssigneeGP Cellulose GmbH
InventorsArthur J. Nonni, Charles E. Courchene, Philip R. Campbell, Steven C. Dowdle, Joel M. Engle, Christopher M. Slone
Life of this patent
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Abstract
A bleached softwood kraft pulp fiber with high alpha cellulose content and increased brightness and whiteness is provided. Methods for making the kraft fiber and products made from it are also described.
Claims14
A kraft pulp fiber made by a method comprising:
- digesting and oxygen delignifying a softwood cellulose fiber to a kappa number of less than about 8;
- and
- bleaching the softwood cellulose fiber in a multi-stage bleaching sequence;
- wherein the first stage of the multi-stage bleaching sequence is a chlorine dioxide D0 stage wherein chlorine dioxide is applied in an amount of greater than about 1% chlorine dioxide on pulp;
- wherein the softwood fiber has an ISO brightness of from about 91% to about 94%, a CIE whiteness of from 85 to about 87, an R18 value of from about 87.5% to about 90%, a length-weighted average fiber length from about 2 mm to about 3.7 mm, a viscosity of less than about 10 mPa·s, and wherein the softwood fiber does not comprise an optical brightening agent.
A softwood kraft fiber having an ISO brightness of from about 91% to about 94%, a CIE whiteness of the fiber of from 85 to about 87, an R18 value from about 87.5% to about 90%, a length-weighted average fiber length from about 2 mm to about 3.7 mm, a viscosity of less than about 10 mPa·s, and wherein the fiber does not comprise an optical brightening agent.
Dependencies are inferred from the claim text.