Method for producing paper, board or the like

• US 20190309476A1
• Filed: 12/15/2016
• Published: 10/10/2019
• Est. Priority Date: 12/15/2015
• Status: Active Grant

• Current Assignee: Kemira Oyj
• Original Assignee: Kemira Oyj
• Inventors: Karisalmi, Kaisa, Lundin, Tom, Virtanen, Mikko, Laukkanen, Antti, McKee, Jason
• Granted Patent: US 10,767,312 B2
• Time in Patent Office: Days
• CPC Class Codes: C08L 1/02 Cellulose; Modified cellulose
• CPC Class Codes: D21H 11/12 Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
• CPC Class Codes: D21H 11/18 Highly hydrated, swollen or fibrillatable fibres
• CPC Class Codes: D21H 17/21 of natural origin; Derivatives thereof
• CPC Class Codes: D21H 17/33 Synthetic macromolecular compounds
• CPC Class Codes: D21H 21/18 Reinforcing agents
• CPC Class Codes: D21H 21/20 Wet strength agents

Abstract

The invention relates to a method for producing paper, board or the like. The method comprises obtaining a thick stock comprising cellulose fibres, forming a fibrous web and drying of drying the fibrous web. A strength agent system, which comprises at least one synthetic or natural polymer, or their mixture, and microfibrillated parenchymal cellulose material originating from non-wood sources, is added to the thick stock. The invention relates also to paper or board produced by the method.

Claims

1. A method for producing paper, board or the like, which comprises

obtaining a thick stock comprising cellulose fibres,

forming a fibrous web,

drying the fibrous web,

wherein

a strength agent system, which comprises at least one synthetic or natural polymer, or their mixture, and microfibrillated parenchymal cellulose material originating from non-wood sources is added to the thick stock.

2. The method according to claim 1, wherein the microfibrillated parenchymal cellulose material originates from vegetables, such as sugar beet pulp, potato pulp, cassava pulp, sweet potato;

fruits, such as citrus peel;

cellulose pith, such as bagasse pith, corn pith, bamboo pith; and

mixtures thereof.

3. The method according to claim 1, wherein the microfibrillated parenchymal cellulose material is obtained by mechanical treatment, such as homogenization, without preceding treatment steps, which are selected from oxidation, extraction and/or washing.

4. The method according to claim 1, wherein the microfibrillated parenchymal cellulose material has

a Brookfield viscosity of at least 10 Pas, preferably at least 100 Pas, measured at concentration of 1.0 weigh-% at 100 rpm shear rate, and/or

a turbidity value less than 1000 NTU, preferably in the range of 100-700 NTU, measured at 0.1 weight-% concentration, and/or

a net charge in the range of −

0.001-−

1.99 meq/g, preferably −

0.01-−

1.50 meq/g, more preferably −

0.05-−

1.0 meq/g, at pH 7.5.

5. The method according to claim 1, wherein the Brookfield viscosity of the microfibrillated parenchymal cellulose material is in the range of 500-2000 Pas, preferably 800-1400 Pas, more preferably 900-1300 Pas.

6. The method according to claim 1, wherein the turbidity of the microfibrillated parenchymal cellulose material may be in the range 375-525 NTU, preferably 490-510 NTU.

7. The method according to claim 1, wherein the strength agent system is added in such amount that the microfibrillated parenchymal cellulose material is added in amount of 1-100 kg, preferably 5-70 kg, more preferably 10-50 kg, even more preferably 15-50 kg, given as dry per ton of dry solids of the fibre stock.

8. The method according to claim 1, wherein the strength agent system comprises 50-99.9 weight-%, preferably 70-99.9 weight-%, more preferably 80-99.5 weight-%, even more preferably 85-90 weight-%, of microfibrillated parenchymal cellulose material, calculated from the dry solids content.

9. The method according to claim 1, wherein that the strength agent system comprises a natural polymer, which is selected from a group consisting of cationic or amphoteric starch, chitin, guargum, carboxymethyl cellulose, and any mixture thereof.

10. The method according to claim 1, wherein the strength agent is a synthetic polymer selected from cationic polyacrylamide (C-PAM), glyoxalated polyacrylamide (G-PAM), amphoteric polyacrylamide, polydiallyldimethylammonium chloride (poly-DADMAC), polyacrylic amide (PAAE), polyvinyl amine (PVAm), polyethylene oxide (PEO), polyethyleneimine (PEI) or a mixture of two or more of these polymers.

11. The method according to claim 10, wherein the average molecular weight of the synthetic polymer is in the range 100 000-20 000 000 g/mol, typically 300 000-8 000 000 g/mol, more typically 300 000-1 500 000 g/mol.

12. The method according to claim 10, wherein the synthetic polymer is a cationic synthetic polymer which has a charge density of 0.5-2 meq/g, preferably 0.3-1.9 meq/g, more preferably 0.4-1.35 meq/g.

13. The method according to claim 10, wherein the synthetic polymer is a cationic synthetic polymer which is a copolymer of methacrylamide or acrylamide and at least one cationic monomer.

14. The method according to claim 1, wherein a cationic retention polymer is added to the stock after the addition of the strength agent system.

15. The method according to claim 14, wherein the cationic retention polymer is cationic polyacrylamide having an average molecular weight of 4 000 000-18 000 000 Da, preferably 4 000 000-12 000 000 Da, more preferably 7 000 000-10 000 000 Da, and/or having a charge density of 0.2-2.5 meq/g, preferably 0.5-1.5 meq/g, more preferably 0.7-1.2 meq/g.

16. The method according to claim 1, wherein the stock comprising cellulose fibres is obtained by using furnish from kraft pulping, chemithermomechanical pulping or by repulping recycled fibres.

18. A paper or board product, having a density in the range of 150-800 kg/m³, produced by a method according to claim 1.

17. Use of microfibrillated material originating from non-wood sources as strength agent in manufacture of paper, board or the like.