Method for the production of paper, paperboard and cardboard
View Patent ↗Process for the production of paper, board and cardboard by draining a paper stock on a wire with sheet formation and drying of the sheets, the sheet formation being carried out in the absence of finely divided inorganic flocculants and (a) polymers comprising vinylamine units and/or polyvinylformamide having a molar mass M w of, in each case, at least 1 million and (b) at least one cationic or nonionic polyacrylamide and/or one cationic or nonionic polymethacrylamide having a molar mass M w of, in each case, at least 2.5 million being used as retention aids.
1. A process for producing paper, board or cardboard comprising:
draining a paper stock on a wire with sheet formation which is carried out in the absence of a finely divided inorganic flocculant and in the presence of a retention aid to obtain a sheet, wherein the retention aid comprises:
(a) at least one hydrolyzed polyvinylformamide having a degree of hydrolysis of 0.5-50% and a weight average molar mass M w of at least 1,200,000, which is prepared by homopolymerizing N-vinylformamide to give poly-N-vinylformamide and subsequently hydrolyzing 0.5-50% of the vinylformamide units to vinylamine units, which is cationic, and which has a charge density of 0.2-4 meq/g; and
(b) at least one cationic poly(meth)acrylamide copolymer having a weight average molar mass M w of at least 3,000,000 and comprising 70-93 mol. % of acrylamide and 7-30 mol. % of at least one cationic monomer, wherein the cationic monomer is selected from the group consisting of dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate, including free bases, salts and/or quaternized forms thereof,
wherein a weight ratio of component (b) to component (a) is 0.25-0.4; and
drying the sheet obtained from said sheet formation.
2. The process according to claim 1 , wherein the cationic monomer is dimethylaminoethyl acrylate methochloride.
3. The process according to claim 1 , wherein the retention aid comprises:
(a) 0.001-0.8 wt. % of the hydrolyzed polyvinylfomamide; and
(b) 0.001-0.8 wt. % of the cationic poly(meth)acrylamide copolymer.
4. The process according to claim 1 , wherein the retention aid comprises:
(a) 0.01-0.5 wt. % of the hydrolyzed polyvinylformamide; and
(b) 0.01-0.2 wt. % of the cationic poly(meth)acrylamide copolymer.
5. The process according to claim 1 , wherein the hydrolyzed polyvinylformamide has a degree of hydrolysis of 1-40%.
6. The process according to claim 1 , wherein the hydrolyzed polyvinylformamide has a degree of hydrolysis of 2-30%.
7. The process according to claim 1 , wherein the cationic poly(meth)acrylamide copolymer has a weight average molar mass M w of 5,000,000 to 15,000,000.
8. The process according to claim 1 , wherein the retention aid comprises:
(b) a mixture comprising: the cationic poly(meth)acrylamide copolymer; and at least one nonionic poly(meth)acrylamide copolymer having a weight average molar mass M w of at least 3,000,000.
9. The process according to claim 8 , wherein the retention aid comprises:
(a) 0.001-0.8 wt. % of the hydrolyzed polyvinylformamide; and
(b) 0.001-0.8 wt. % of the mixture.
10. The process according to claim 8 , wherein the retention aid comprises:
(a) 0.01-0.5 wt. % of the hydrolyzed polyvinylformamide; and
(b) 0.01-0.2 wt. % of the mixture.
11. A process for producing paper, board or cardboard comprising:
draining a paper stock on a wire with sheet formation which is carried out in the absence of a finely divided inorganic flocculant and in the presence of a retention aid to obtain a sheet, wherein the retention aid comprises:
(a) at least one hydrolyzed polyvinylformamide having a weight average molar mass M w of at least 1,200,000, which is prepared by homopolymerizing N-vinylformamide to give poly-N-vinylformamide and subsequently hydrolyzing the vinylformamide units to vinylamine units, which is cationic, and which has a charge density of 0.2-4 meq/g; and
(b) at least one cationic poly(meth)acrylamide copolymer having a weight average molar mass M w of at least 3,000,000 and comprising 70-93 mol. % of acrylamide and 7-30 mol. % of at least one cationic monomer, wherein the cationic monomer is selected from the group consisting of dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate, including free bases, salts and/or quaternized forms thereof,
wherein a weight ratio of component (b) to component (a) is 0.25-0.4; and
drying the sheet obtained from said sheet formation.
12. The process according to claim 11 , wherein the cationic monomer is dimethylaminoethyl acrylate methochloride.
13. The process according to claim 11 , wherein the retention aid comprises:
(a) 0.001-0.8 wt. % of the hydrolyzed polyvinylformamide; and
(b) 0.001-0.8 wt. % of the cationic poly(meth)acrylamide copolymer.
14. The process according to claim 11 , wherein the retention aid comprises:
(a) 0.01-0.5 wt. % of the hydrolyzed polyvinylformamide; and
(b) 0.01-0.2 wt. % of the cationic poly(meth)acrylamide copolymer.
15. The process according to claim 11 , wherein the hydrolyzed polyvinylformamide has a degree of hydrolysis of 0.5-50%.
16. The process according to claim 11 , wherein the hydrolyzed polyvinylformamide has a degree of hydrolysis of 1-40%.
17. The process according to claim 11 , wherein the cationic poly(meth)acrylamide copolymer has a weight average molar mass M w of 5,000,000 to 15,000,000.
18. The process according to claim 11 , wherein the retention aid comprises:
(b) a mixture comprising: the cationic poly(meth)acrylamide copolymer; and at least one nonionic poly(meth)acrylamide copolymer having a weight average molar mass M w of at least 3,000,000.
19. The process according to claim 18 , wherein the retention aid comprises:
(a) 0.001-0.8 wt. % of the hydrolyzed polyvinylformamide; and
(b) 0.001-0.8 wt. % of the mixture.
20. The process according to claim 18 , wherein the retention aid comprises:
(a) 0.01-0.5 wt. % of the hydrolyzed polyvinylformamide; and
(b) 0.01-0.2 wt. % of the mixture.