Patents Assigned to Borregaard A/S
  • Method for the production of unbleached sulphite cellulose or bleached cellulose from a defibrated knot pulp
    Patent number: 4230524
    Abstract: Knots separated from sulphite cellulose produced by a sulphite cellulose cooking process are converted to unbleached sulphite cellulose by first separating and defibrating the sulphite knots and then treating the defibrated sulphite knots with oxygen under pressure in an alkaline milieu at an elevated temperature. The resultant cellulose may be bleached by itself, or mixed with sulphite cellulose produced from knot-free cellulose pulp for bleaching therewith.
    Type: Grant
    Filed: June 28, 1979
    Date of Patent: October 28, 1980
    Assignee: Borregaard A/S
    Inventor: Ketil Hasvold