Process for production of paper or board

Patent metadata

Field	Value
Publication number	US-9605382-B2
Application number	US-201414774906-A
Country	US
Kind code	B2
Filing date	Mar 7, 2014
Priority date	Mar 26, 2013
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

The invention relates to a process for production of paper or board comprising providing a stock comprising cellulose fibers, adding a mixture comprising microfibrillated cellulose and a strength additive to the stock, adding a microparticle to the stock after the addition of said mixture, dewatering the stock on a wire to form a web, and drying the web.

First claim

The invention claimed is:

1. A process for production of paper or board comprising the steps of:
a) providing a stock comprising cellulose fibers,
b) preparing a premixture of microfibrillated cellulose (MFC) and a strength additive, wherein the strength additive comprises starch and at least one synthetic polymer selected from the group consisting of cationic polyacrylamide (C-PAM), anionic polyacrylamide (A-PAM), glyoxylated polyacrylamide (G-PAM), amphoteric polyacrylamide, polydiallyldimethylammonium chloride (poly-DADMAC), polyacrylic amide (PAAE), polyvinyl amine (PVAm), polyethylene oxide (PEO), and polyethyleneimine (PEI);
c) adding the premixture into the stock,
d) adding a microparticle selected from silica-based microparticle, a natural silicate microparticle, a synthetic silcate microparticle or a mixture thereof to the mixture of step c,
e) dewatering the mixture of step d) on a wire to form a web, and
f) drying the web.

2. The process of claim 1 wherein the strength additive comprises chitosan, guar gum, carboxymethyl cellulose (CMC) or a mixture thereof.

3. The process of claim 1 wherein an average molecular weight of the synthetic polymer is in range of 100 000-20 000 000 g/mol.

4. The process of claim 3 , wherein the average molecular weight of the synthetic polymer is in typically 300 000-8 000 000 g/mol.

5. The process of claim 4 , wherein the average molecular weight of the synthetic polymer is 300 000-1 500 000 g/mol.

6. The process of claim 1 wherein said microparticle is added to a short circulation of a paper machine, the consistency preferably being 0.2-2.0%, by weight.

7. The process of claim 1 wherein the microparticle is a silica-based microparticle and it is added in an amount of 0.1-4 kg on dry basis per ton of dry solids of the stock.

8. The process of claim 7 wherein the microparticle is added in an amount of 0.33-0.8 kg on dry basis per ton of dry solids of the stock.

9. The process of claim 1 wherein the microparticle is a natural or a synthetic silicate microparticle and is added in an amount of 0.1-10 kg on dry basis per ton of dry solids of the stock.

10. The process of claim 9 , wherein the microparticle is bentonite or hectorite.

11. The process of claim 9 wherein the microparticle is added in an amount of 2-5 kg on dry basis per ton of dry solids of the stock.

12. The process of claim 1 wherein the microfibrillated cellulose is added in an amount of 5-100 kg on dry basis per ton of dry solids of the stock.

13. The process of claim 12 wherein the microfibrillated cellulose is added in an amount of 15-50 kg on dry basis per ton of dry solids of the stock.

14. The process of claim 1 wherein the strength additive is added in an amount of 5-100 kg on dry basis per ton of dry solids of the stock.

15. The process of claim 14 wherein the strength additive is added in an amount of 15-50 kg on dry basis per ton of dry solids of the stock.

16. The process of claim 1 wherein said premixture is added to a thick stock flow of a paper machine, the consistency being 2-6% by weight.

17. The process of claim 16 , wherein said premixture is added to a thick stock flow of a paper machine, the consistency 3-5% by weight.

18. The process of claim 6 wherein the microparticle is added to a short circulation of a paper machine, the consistency being 0.31.5% by weight.

19. The process of claim 1 wherein the microfibrillated cellulose is anionic.

Assignees

• Kemira Oyj

Inventors

• Virtanen Mikko

Classifications

• D21H17/56

  Polyamines; Polyimines; Polyester-imides · CPC title

• D21H11/18

  Highly hydrated, swollen or fibrillatable fibres · CPC title

• D21H17/375

  Poly(meth)acrylamide · CPC title

• D21H17/28 Primary

  Starch · CPC title

• D21H17/69

  modified, e.g. by association with other compositions prior to incorporation in the pulp or paper · CPC title