# US 10,767,315 B2 · System and method for manufacture of paper, board or the like

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- Number: US 10,767,315 B2
- Document ID: US10767315B2
- Status: Granted
- Kind: B2
- Application number: 16/078,034
- Filed: 2017-03-22
- Published: 2019-02-14
- Granted: 2020-09-08
- Earliest claimed: 2016-03-22
- Assignees: Kemira Oyj
- Applicants: Kemira Oyj
- Inventors: Matti Hietaniemi; Asko Karppi
- Web page: https://patentgrep.com/patent/US10767315B2

## CPC

- D21H 21/10: Retention agents or drainage improvers
- D21H 17/29: cationic
- D21H 17/375: {Poly(meth)acrylamide}
- D21H 17/44: cationic
- D21H 17/66: Salts, e.g. alums
- D21H 17/68: siliceous, e.g. clays
- D21H 21/18: Reinforcing agents
- Y02W 30/64: Paper recycling
- D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

Drainage and press dewatering system for manufacture of paper, board or the like, comprising (a) amphoteric polyacrylamide, which is a copolymer obtained by polymerizing (meth)acrylamide and 1-80 mol-% of cationic monomers and/or 0.1-70 mol-% of anionic monomers, the polyacrylamide having an intrinsic viscosity in the range of 6-38 dl/g, (b) inorganic microparticles of siliceous material, such as colloidal silica or bentonite, and (c) a high-charged cationic coagulant having a charge density over 5 meq/g and preferably over 6 meq/g determined at pH 6 and selected from aluminium based coagulants, organic polymers and mixtures thereof.

## Claims

### Claim 1

A drainage and a press dewatering system for manufacture of paper, board or the like, comprising:
(a) an amphoteric polyacrylamide, which is a copolymer obtained by polymerizing (meth)acrylamide and 1-25 mol-% of cationic monomers and 0.1-24 mol-% of anionic monomers, the polyacrylamide having an intrinsic viscosity in a range of 6-38 dl/g determined in 1 M NaCl at 25° C.,
(b) inorganic microparticles of siliceous material, selected from colloidal silica or bentonite, and
(c) a high-charged cationic coagulant having a charge density over 5 meq/g determined at pH 6 and selected from aluminum based coagulants, organic polymers and mixtures thereof.

### Claim 2 (depends on 1)

The system according to claim 1, wherein the amphoteric polyacrylamide has the intrinsic viscosity in a range of 6-20 dl/g, determined in 1 M NaCl at 25° C.

### Claim 3 (depends on 1)

The system according to claim 1, wherein the amphoteric polyacrylamide has a cationic net charge, determined by Mütek PCD at pH 2.7.

### Claim 4 (depends on 1)

The system according to claim 1, wherein a cationic charge density of the amphoteric polyacrylamide is in a range of 0.2-4 meq/g, determined by Mütek PCD at pH 2.7.

### Claim 5 (depends on 1)

The system according to claim 1, wherein the amphoteric polyacrylamide is the copolymer obtained by polymerizing (meth)acrylamide, 4-17 mol-% of cationic monomers and 0.1-15 mol-% of anionic monomers.

### Claim 6 (depends on 1)

The system according to claim 1, wherein the amphoteric polyacrylamide is obtained by gel polymerization, where content of non-aqueous solvent during the polymerization is less than 10 weight-%.

### Claim 7 (depends on 6)

The system according to claim 6, wherein the polymer content of the amphoteric polyacrylamide is at least 60 weight-%.

### Claim 8 (depends on 1)

The system according to claim 1, wherein the amphoteric polyacrylamide comprises <0.01 mol-%, preferably of branching agent or cross-linking agent.

### Claim 9 (depends on 1)

The system according to claim 1, wherein the high-charged cationic coagulant is:
aluminum based coagulant, which is selected from a group comprising aluminum sulphate, aluminum chloride, polyaluminum chloride (PAC), polyaluminum silicate, polyaluminum sulphate (PAS), polyaluminum silica sulphate, sodium aluminate, alum and any of their mixture, and/or
organic polymer, which is selected from polyethylenimine, polyamine, polyDADMAC, polyAPTAC, polyMAPTAC, poly-ADAM-CI and any of their mixture.

### Claim 10 (depends on 1)

The system according to claim 1, wherein the system further comprises cationic starch and/or cationic polyacrylamide.

### Claim 11 (depends on 1)

The system according to claim 1 used in manufacturing of kraft paper, liner board, test liner, fluting, sack paper, white lined chipboard, core board or folding boxboard.

### Claim 12

A method for manufacture of paper, board or the like, comprising:
obtaining a fibre stock comprising fibres originating from recycled fibre material, unbleached kraft pulping and/or unbleached semichemical pulping, whereby the fibre stock has a conductivity of at least 1 mS/cm;
adding to the fibre stock an aqueous solution of a water-soluble amphoteric polyacrylamide, which is a copolymer obtained by polymerizing (meth)acrylamide and 1-25 mol-% of cationic monomers and 0.1-24 mol-% of anionic monomers, the polyacrylamide having an intrinsic viscosity in a range of 6-38 dl/g determined in 1 M NaCl at 25° C.;
adding to the fibre stock inorganic microparticles of siliceous material, selected from colloidal silica or bentonite;
adding to the fibre stock or to an aqueous flow to be combined with the fibre stock a high-charged cationic coagulant having a charge density over 5 meq/g determined at pH 6 and selected from aluminum based coagulants, organic polymers and mixtures thereof; and
forming the fibre stock into a fibrous web.

### Claim 13 (depends on 12)

The method according to claim 12, wherein the amphoteric polyacrylamide is added in an amount of 100-1000 g/t dry fibre stock.

### Claim 14 (depends on 12)

The method according to claim 12, wherein the amphoteric polyacrylamide is added to thin stock having consistency of 5-20 g/l for improving drainage or thick stock having consistency of >20 g/l for improving paper strength properties.

### Claim 15 (depends on 12)

The method according to claim 12, wherein the amphoteric polyacrylamide is added after last shear stage before a headbox of a paper or board machine.

### Claim 16 (depends on 12)

The method according to claim 12, wherein the inorganic microparticles of colloidal silica are added in the amount of 100-600 g/t dry fibre stock, or the inorganic microparticles of bentonite are added in an amount of 1-4 kg/t dry fibre stock.

### Claim 17 (depends on 12)

The method according to claim 12, wherein the inorganic microparticles are added to thin stock having consistency of 5-20 g/l.

### Claim 18 (depends on 12)

The method according to claim 12, wherein the amphoteric polyacrylamide, inorganic microparticles, and high-charged cationic coagulant are added separately from each other.

### Claim 19 (depends on 18)

The method according to claim 18, wherein the amphoteric polyacrylamide is added after the addition of the microparticles and the high-charged cationic coagulant.

### Claim 20 (depends on 12)

The method according to claim 12, wherein the coagulant is aluminum based coagulant, which is added in an amount of 100-700 g/t dry fibre stock as Al3−, or the coagulant is organic polymer which is added in an amount of 50-1000 g/ton dry pulp.

### Claim 21 (depends on 12)

The method according to claim 12, wherein the fibre stock comprises at least 20 weight-% of fibres originating from recycled fibre material.

### Claim 22 (depends on 12)

The method according to claim 12, wherein the fibre stock has a conductivity of at least 2 mS/cm.

### Claim 23 (depends on 12)

The method according to claim 12, wherein the fibre stock has a starch content of at least 1 weight-%, based on dry total solids.

### Claim 24 (depends on 12)

The method according to claim 12, wherein the fibre stock has an ash content of at least 10 weight-%, based on dry total solids.