Method for manufacture of paper or board and paper or board obtained by the method

Patent metadata

Field	Value
Publication number	US-11535985-B2
Application number	US-202016916173-A
Country	US
Kind code	B2
Filing date	Jun 30, 2020
Priority date	Jul 1, 2019
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

A method for manufacture of paper or board, in which method an inverted solution of cationic polymer is added to the fiber suspension for providing retention enhancement without over-flocculating fiber stock and destruction sheet formation and/or improving drainage and enhancing or at least maintaining strength of paper or board, An inverted solution has a bulk viscosity of 50-150 mPas at 0.2 weight-% cationic polymer concentration and inverted solution comprises cationic polymer obtained by reverse phase emulsion polymerization of a monomer blend comprising non-ionic monomers, 15-50 mol-% cationic monomers, an optionally at most 50 ppm of a crosslinking agent, and a chain transfer agent, and the obtained reverse phase emulsion of cationic polymer is inverted into an aqueous solution.

First claim

The invention claimed is:

1. A method for manufacture of paper or board, where a fiber web is formed from an aqueous suspension of fibers, the method comprising:
providing an aqueous fiber suspension, which comprises at least 50 weight-% of recycled fiber material and/or coated broke, based on dry paper or board;
optionally diluting the aqueous fiber suspension;
adding to the fiber suspension having consistency of above 20 g/l an inverted solution of cationic polymer,
the inverted solution of cationic polymer having a bulk viscosity of 50 to 150 mPas at 0.2 weight-% cationic polymer concentration, and comprising a reverse phase emulsion of a branched or unbranched cationic polymer having a standard viscosity of 1.5-3.5 mPas measured by Brookfield viscometer with UL adapter at 25° C. on a 0.1% by weight, polymer solution in 1 M NaCl, and said cationic polymer being obtained by reverse phase emulsion polymerization of a monomer blend comprising non-ionic monomers, 20-40 mol-% cationic monomers, optionally at most 50 ppm of a crosslinking agent;
delivering the aqueous fiber suspension to a headbox, draining the aqueous fiber suspension on a wire screen to form a wet fibrous web; and
pressing and drying the wet fibrous web to obtain a web of paper or board.

2. The method according to claim 1 , wherein a cationic net charge of the cationic polymer is in the range of 1.1-4.5 meq/g (dry), at pH 7.

3. The method according to claim 1 , wherein the reverse phase emulsion of cationic polymer has a standard viscosity of 1.7-3.3 mPas, measured by Brookfield viscometer with UL adapter at 25° C. on a 0.1% by weight polymer solution in 1M NaCl.

4. The method according to claim 1 , wherein the amount of the crosslinking agent is preferably in the range of 5-30 ppm.

5. The method according to claim 1 , wherein the monomer blend comprises one or more ethylenically unsaturated monomers.

6. The method according to claim 1 , wherein the cationic monomers comprise one or more selected from diallyldimethylammonium chloride (DADMAC); acryloyloxyethyltrimethylammonium chloride; methacrylates of N,N-dialkylaminoalkyl compounds; and quaternaries and salts thereof, such as N,N-dimethylaminoethylacrylate methyl-chloride salt; monomers of N,N-dialkylaminoalkyl (meth)acrylamides; and salts and quaternaries thereof, such as N,N-dialkylaminoethylacrylamides; methacrylamidopropyltrimethylammonium chloride; 1-methacryloyl-4-methyl piperazine and the like.

7. The method according to claim 1 , wherein the nonionic monomers comprise one or more selected from acrylamide; methacrylamide; N-alkyl acrylamides, such as N-methylacrylamide, N,N-dialkylacrylamides, such as N,N-dimethylacrylamide; methyl acrylate; methyl methacrylate; acrylonitrile; N-vinylmethylacetamide or formamide; N-vinyl acetate or vinyl pyrrolidone, and the like.

8. The method according to claim 1 , wherein said inverted solution is added to fiber suspension having consistency of above 30 g/l.

9. The method according to claim 1 , wherein a part of the inverted solution is added to fiber suspension having consistency of below 20 g/l.

10. The method according to claim 1 , wherein said inverted solution is added to the fiber suspension before washing and/or cleaning and/or thickening of the fiber suspension.

11. The method according to claim 1 , wherein said inverted solution is added to fiber suspension having consistency of above 20 g/l in an amount of 0.9-2.72 kg (as is)/ton produced paper or board.

12. The method according to claim 11 , wherein said inverted solution is added to fiber suspension having consistency of above 20 g/l in an amount of 1.36-2.72 (as is)/ton produced paper or board.

13. The method according to claim 1 , wherein a cationic net charge of the cationic polymer is in the range of 1.5-4.5 meq/g (dry), at pH 7.

14. The method according to claim 13 , wherein a cationic net charge of the cationic polymer is in the range of 3.5-4.5 meq/g (dry), at pH 7.

15. The method according to claim 1 , wherein the reverse phase emulsion of cationic polymer has a standard viscosity of 1.7-3.0 mPas, measured by Brookfield viscometer with UL adapter at 25° C. on a 0.1% by weight polymer solution in 1M NaCl.

16. The method according to claim 1 , wherein the reverse phase emulsion of cationic polymer has a standard viscosity of 1.7-2.0 mPas, measured by Brookfield viscometer with UL adapter at 25° C. on a 0.1% by weight polymer solution in 1M NaCl.

17. The method according to claim 1 , wherein the fiber suspension comprises at least 60 weight-% of recycled fiber material and/or coated broke, based on dry paper or board.

18. The method according to claim 17 , wherein the fiber suspension comprises at least 70 weight-% of recycled fiber material and/or coated broke, based on dry paper or board.

19. The method according to claim 18 , wherein the fiber suspension comprises at least 80 weight-% of recycled fiber material and/or coated broke, based on dry paper or board.

20. The method according to claim 19 , wherein the fiber suspension comprises 100 weight-% of recycled fiber material and/or coated broke, based on dry paper or board.

21. A paper or board obtained by a method according to claim 1 .

Assignees

• Kemira Oyj

Inventors

• Luo Yuping
• Riser Jennifer
• Dang Zheng
• Chen Junhua
• Robinson Ronald
• Pencek Andrew
• Lukasik Barbara

Classifications

• D21H23/765

  Addition of all compounds to the pulp · CPC title

• D21H21/10 Primary

  Retention agents or drainage improvers · CPC title

• D21H21/20

  Wet strength agents · CPC title

• D21H21/18

  Reinforcing agents · CPC title

• D21H17/375 Primary

  Poly(meth)acrylamide · CPC title