Back to results
US 8,273,216 B2Granted
Process for the production of paper
AssigneeAkzo Nobel N.V.
InventorsFredrik Solhage, Joakim Carlén, Birgitta Johansson
Life of this patent
Estimating the term…
Abstract
The present invention relates to a process for producing paper which comprises: providing an aqueous suspension comprising cellulosic fibers, adding to the suspension, after all points of high shear, a cationic polysaccharide; and a polymer P2 being an anionic polymer; and, dewatering the obtained suspension to form paper.
Claims14
A process for producing paper which comprises:
- (i) providing an aqueous suspension comprising cellulosic fibers,
- (ii) adding to the suspension after all points of high shear:
- a polymer P1 being a water-soluble cationic acrylamide-based polymer having an average molecular weight of at least about 1,000,000 prepared by polymerizing a composition comprising a monomer mixture comprising one or more cationic monomers represented by the general structural formula (II)
- wherein R1 is H or CH3;
- R2 and R3 are each H or a hydrocarbon group having from 1 to 2 carbon atoms;
- A is O;
- B is an alkyl or alkylene group having from 2 to 8 carbon atoms;
- R4 is H or a hydrocarbon group having from 1 to 2 carbon atoms;
- and X− is an anionic counterion;
- a cationic starch having a degree of cationic substitution (DSC) from 0.01 to 0.5, a charge density of from about 0.05 to about 6.0 meq/g and a weight average molecular weight of above about 1,000,000;
- and
- a polymer P2 being an anionic polymer selected from anionic silica-based polymers comprising anionic silica-based particles having an average particle size in the range of from about 1 to about 10 nm, and a specific surface area within the range of from 50 to 1000 m2/g;
- and
- (iii) dewatering the obtained suspension to form paper.
11 more elements
A process for producing paper which comprises:
- (i) providing an aqueous suspension comprising cellulosic fibers,
- (ii) adding to the suspension after all points of high shear:
- a polymer P1 being a water-soluble cationic acrylamide-based polymer having an average molecular weight of at least about 1,000,000 prepared by polymerizing a composition comprising a monomer mixture comprising one or more cationic monomers represented by the general structural formula (II)
- wherein R1 is H or CH3, R2 and R3 are each H or a hydrocarbon group having from 1 to 2 carbon atoms;
- A is O;
- B is an alkyl or alkylene group having from 2 to 8 carbon atoms;
- R4 is H or a hydrocarbon group having from 1 to 2 carbon atoms;
- and X− is an anionic counterion;
- a cationic polysaccharide having a degree of substitution (DSc) within the range of from about 0.01 to about 0.5 and a weight average molecular weight of above about 1,000,000;
- and
- a polymer P2 being an anionic polymer selected from anionic silica-based polymers comprising anionic silica-based particles having an average particle size in the range of from about 1 to about 10 nm, and a specific surface area within the range of from 50 to 1000 m2/g;
- said points of high shear comprising pumping and cleaning stages;
- the obtained suspension from step (ii) being fed to a headbox which ejects the suspension comprising polymer P1, cationic starch, and polymer P2 onto a forming wire for drainage to form paper, wherein the stages of pumping and cleaning comprise fan pumps, pressure screens and centri-screens.
10 more elements
Dependencies are inferred from the claim text.