Lumen-loaded paper pulp, its production and use
AssigneePulp and Paper Research Institute of Canada
InventorsHarold V. Green, Thomas J. Fox, Anthony M. Scallan
Life of this patent
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Abstract
Paper of improved properties is produced from pulp in which filler is selectively loaded within the fiber lumens by agitating a suspension of pulp and filler until the fiber lumens become loaded with filler, separating the residual suspended filler from the loaded fibers and vigorously washing the pulp until substantially all of the filler on the external surfaces of the fibers is removed.
Claims20
Unbleached kraft paper in which substantially all of the filler is within the lumens of the cellulose fibers, said paper having improved strength properties compared to a corresponding conventionally-filled paper containing the same amount of the same filler.
A bleached kraft paper in which substantially all of the filler is within the lumens of the cellulose fibers, said paper having improved strength properties compared to a corresponding conventionally-filled paper containing the same amount of the same filler.
A fine printing or writing paper in which substantially all of the filler is within the lumens of the cellulose fibers, said paper having improved strength properties compared to a corresponding conventionally-filler paper containing the same amount of the same filler.
A lightweight newsprint paper in which substantially all of the filler is within the lumens of the cellulose fibers, said paper having improved strength properties compared to a corresponding conventionally-filled paper containing the same amount of the same filler.
A filled paper in which substantially all of the filler is within the lumens of the cellulose fibers, said paper having improved strength properties compared to a corresponding conventionally-filled paper containing the same amount of the same filler, wherein the paper is filled to an ash content of at least 6% and the filler is selected from one or more of the group consisting of titanium dioxide, clay, calcium carbonate, alumina, silica and polystyrene pigments.
In a process for the production of filled paper wherein the starting pulp is mixed with an amount of filler in excess of that desired in the paper and the excess filler not retained by the pulp is recycled, the improvement which comprises producing paper having higher strength than corresponding paper conventionally filled to the same filler content by filling the pulp by the steps of
- (a) agitating a suspension of the paper pulp and an excess of insoluble filler having an average particle size smaller than the average pore size of the lumen entrances of the pulp fibers, until the pulp is loaded with filler higher than the level desired in the paper and the fiber lumens become loaded with filler to the level desired in the paper;
- (b) separating the filler-containing pulp from the suspension of residual filler;
- (c) vigorously washing the filler pulp until substantially all of the filler on the external surfaces of the fibers is removed, thereby reducing the loss in strength values in the paper normally associated with filling paper;
- and
- (d) recovering on fresh pulp residual filler separated in Step (b) from the filler-containing pulp.
A process according to claim 11 wherein the retention aid is alum.
Dependencies are inferred from the claim text.