Process for the manufacture of paper
AssigneeEka Nobel AB
InventorsBruno Carre/, Ulf Carlson
Life of this patent
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Abstract
A process for improved dewatering and retention in the manufacture of paper, where a retention agent containing anionic groups and being based on a polysaccharide or being an acrylamide-based polymer and an alkaline solution of an aluminate are added to the stock containing lignocellulose-containing fibres and optionally fillers. The pH of the stock prior to the addition of the aluminate should be below about 7 to obtain the desired cationic aluminum hydroxide complexes in the stock. The present process is cost effective and insensitive to the content of calcium in the white water.
Claims13
A process for the production of paper on a wire by forming and dewatering a stock of lignocellulose-containing fibers, comprising the steps of sequentially adding to said stock of lignocelluosic fibers having a pH within the range of from 3.0 to 7.0:
- (a) an alkaline solution of an aluminate, said aluminate being added in an amount of at least 0.001% by weight, calculated as Al.sub.2 O.sub.3 and based on dry fibers;
- (b) a retention agent containing anionic and cationic groups, said retention agent being based on a polysaccharide or being an acrylamide-based polymer, the retention agent based on a polysaccharide is added in an amount of at least 0.05% by weight, based on dry fibers, and the retention agent being an acrylamide-based polymer is added in an amount of at least 0.005% by weight, based on dry fibers;
- and
- (c) an anionic inorganic colloid selected from the group consisting of bentonite, montmorillonite, titanyl sulphate sols, silica sols, aluminum modified silica sols, and aluminum silicate sols, said anionic inorganic colloid being added in an amount of at least 0.005% by weight, based on dry fibers;
- wherein the pH of the stock after the addition of aluminate is in the range of from 3.5 to 7.
Dependencies are inferred from the claim text.