US 4,925,530 A · Loaded paper

Abstract

Aqueous suspensions of papermaking fibres and filler are each separately treated with an anionic or a cationic polymer, after which the filler (preferably) or the papermaking fibre is treated with a polymer of opposite charge to that used in the initial treatment. The filler and papermaking suspensions are then mixed to form a papermaking stock, with dilution as necessary before, during or after the mixing operation. This stock is then used to form a loaded paper web in conventional manner. The initial treating polymer is preferably a papermaking retention aid or flocculant, e.g. a cationic polyarcylamide or an amine/amide/epichlorohydrin copolymer in the case of cationic materials or an anionic polyacrylamide in the case of anionic materials. The further treating polymer is preferably an anionic or cationic starch, depending on the charge of the initial treating polymer.

Claims37

Dependent claims

A process for the production of loaded paper from papermaking fibre and filler, comprising the steps of:

(a) treating the papermaking fibre in an aqueous medium with a charged synthetic polymer;
(b) separately treating the filler in an aqueous medium with a charged synthetic polymer, with the proviso that if the charged synthetic polymer used to treat the filler is anionic it is selected from papermaking flocculents and retention aids;
(c) selecting the charged synthetic polymer used in step (a) and the charged synthetic polymer used in step (b) such that both have the same charge polarity;
(d) additionally treating the filler with a charged polymer of opposite charge polarity from that of the polymer(s) used in steps (a) and (b);
(e) mixing aqueous suspensions of treated filler and treated papermaking fibre from steps (a), (b) and (d) to form a papermaking stock, diluting as necessary before, during or after the mixing operation;
and
(f) draining the papermaking stock to form a loaded paper web, wherein the filler, papermaking fibre and charged polymers are used in amounts effective to produce loaded paper.

4 more elements

Dependencies are inferred from the claim text.

Loaded paper

Life of this patent

Loaded paper

Life of this patent

Abstract

Claims37