Method for producing paper, paperboard and cardboard
View Patent ↗A process for the production of paper, board and cardboard by draining a paper stock containing interfering substances in the presence of polymers which contain vinylamine units and which have an average molar mass M w of at least 1 million, a high-consistency stock first being prepared, at least one polymer containing vinylamine units and having an average molar mass M w of at least 1 million and a degree of hydrolysis of from 1 to 20 mol % being metered into the high-consistency stock, the high-consistency stock being diluted to a low-consistency stock by adding water, and the low-consistency stock being drained, the polymers being hydrolyzed homo- or copolymers of N-vinylcarboxamides additives for reducing deposits in the wire part, press section and drying section of paper machines.
1. A process for producing paper, board or cardboard by draining a paper stock comprising interfering substances in the presence of one or more polymers which comprise vinylamine units and which have an average molar mass M w of at least 1 million, the process comprising preparing a high-consistency paper stock, metering as said one or more polymers, at least one copolymer of (1) an N-vinyl carboxamide and (2) at least one other ethylenically unsaturated monomer selected from the group consisting of a monoethylenically unsaturated C 3 - to C 5 -carboxylic acid, an ester thereof, a nitrile thereof and an amide thereof, said copolymer comprising vinylamine units and having an average molar mass M w of at least 1 million and a degree of hydrolysis of from 1 to 20 mol % into the high-consistency stock, diluting with water the high-consistency stock to a low-consistency stock, and draining the low-consistency stock.
2. The process according to claim 1 , wherein the consistency of the high-consistency stock is more than 2% by weight, based on dry paper stock, and the degree of hydrolysis of the polymers is from 3 to 15 mol %.
3. The process according to claim 1 , wherein the consistency of the high-consistency stock is from 3.0 to 6.0% by weight, based on dry paper stock, and the degree of hydrolysis of the polymers is from 5 to 12 mol %.
4. The process according to claim 1 , wherein the consistency of the high-consistency stock is from 3.5 to 4.5% by weight, based on dry paper stock, and wherein the consistency of the low-consistency stock is brought to a concentration below 1.5% by weight, based on dry paper stock.
5. The process according to claim 1 , wherein the N-vinyl carboxamide is N-vinylformamide.
6. The process according to claim 1 , wherein said copolymer comprises from 95 to 10 mol % of N-vinylformamide and from 5 to 90 mol % of said at least one other ethylenically unsaturated monomer.
7. The process according to claim 6 , wherein said at least one other ethylenically unsaturated monomer is an ester of acrylic acid or methacrylic acid derived from an alcohol of 1 to 6 carbon atoms.
8. The process according to claim 1 , wherein at least one retention aid is metered into the low-consistency stock.
9. The process according to claim 1 , wherein the amount of the polymers containing vinylamine units and metered into the high-consistency stock is from 0.002 to 0.1% by weight, based on dry paper stock.
10. The process according to claim 1 , wherein the high-consistency stock comprising interfering substances comprises coated broke.
11. A method for reducing deposits in at least one of the wire part, press section and drying section of a paper machine in the production of paper, board or cardboard, comprising adding at least one copolymer of (1) an N-vinyl carboxamide and (2) at least one other ethylenically unsaturated monomer selected from the group consisting of a monoethylenically unsaturated C 3 - to C 5 -carboxylic acid, an ester thereof, a nitrile thereof and an amide thereof, said copolymer having a degree of hydrolysis of from 1 to 20 mol % and an average molar mass M w of at least 1 million as an additive to a high-consistency stock containing interfering substances.
12. The process according to claim 11 , wherein the high-consistency stock comprising interfering substances comprises coated broke.
13. The method according to claim 11 , wherein the consistency of the high-consistency stock is more than 2% by weight, based on dry paper stock, and the degree of hydrolysis of the polymers is from 3 to 15 mol %.
14. The method according to claim 11 , wherein the consistency of the high-consistency stock is from 3.0 to 6.0% by weight, based on dry paper stock, and the degree of hydrolysis of the polymers is from 5 to 12 mol %.
15. The method according to claim 11 , wherein the consistency of the high-consistency stock is from 3.5 to 4.5% by weight, based on dry paper stock.
16. The method according to claim 11 , wherein the N-vinyl carboxamide is N-vinylformamide.
17. The method according to claim 11 , wherein said copolymer comprises from 95 to 10 mol % of N-vinylformamide and from 5 to 90 mol % of said at least one other ethylenically unsaturated monomer.
18. The method according to claim 17 , wherein said at least one other ethylenically unsaturated monomer is an ester of acrylic acid or methacrylic acid derived from an alcohol of 1 to 6 carbon atoms.
19. The method according to claim 11 , wherein the amount of the at least one copolymer and metered into the high-consistency stock is from 0.002 to 0.1% by weight, based on dry paper stock.