Papermaking agent system, method for making a papermaking agent system and its use

Patent metadata

Field	Value
Publication number	US-2016273166-A1
Application number	US-201314442433-A
Country	US
Kind code	A1
Filing date	Nov 13, 2013
Priority date	Nov 13, 2012
Publication date	Sep 22, 2016
Grant date	—

Abstract

The invention relates to a papermaking agent system in liquid form, which comprises (i) cationic starch solution, prepared by cooking a starch mixture comprising a starch component and a water component, and (ii) polymer composition, which has anionic and cationic groups and a cationic net charge of >0.1 meq/g. The polymer composition comprises or originates from at least one of constituents a), b) or c). Constituent a) contains an amphoteric polymer, which is a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, and anionic and cationic groups attached to the copolymer. Constituent b) contains a first polymer, which is a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, and anionic or cationic groups attached to the copolymer, as well as a second polymer, which comprises groups with opposite charge than the first polymer. Constituent c) contains a third polymer, which comprises a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, as well as hydrolytically unstable cationic groups attached to the copolymer. Constituent a), b) or c) is added to one of the components of the starch mixture or to the starch mixture before the cooking of the starch mixture, and/or constituent a) or b) is added to the cationic starch solution after cooking of the starch mixture. The invention relates also to the use of the papermaking agent system and to a method for its preparation.

First claim

1 . Papermaking agent system in liquid form, which comprises
(i) cationic starch solution, prepared by cooking a starch mixture comprising a starch component and a water component, and (ii) polymer composition, which has anionic and cationic groups and which has a cationic net charge of >0.1 meq/g, preferably >0.5 meq/g, at pH 7, the polymer composition comprising, or originating from, at least one of constituents a), b) or c), where
constituent a) contains an amphoteric polymer, which is a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, and anionic and cationic groups attached to the copolymer,
constituent b) contains a first polymer, which is a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, and anionic or cationic groups attached to the copolymer, as well as
a second polymer, which comprises groups with opposite charge than the first polymer,

constituent c) contains a third polymer, which comprises a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, as well as hydrolytically unstable cationic groups attached to the copolymer,
wherein constituent a), b) or c) is added to one of the components of the starch mixture or to the starch mixture before the cooking of the starch mixture, and/or constituent a) or b) is added to the cationic starch solution after cooking of the starch mixture.

2 . Papermaking agent system according to claim 1 , characterised in that the constituent a) and/or constituent b) is added before the cooking of the starch mixture and the cationic groups are hydrolytically stable.

3 . Papermaking agent system according to claim 2 , characterised in that the hydrolytically stable cationic groups originate from monomers selected from the group consisting of [3-(acryloylamino)propyl] trimethylammonium chloride, [3-(methacryloylamino)propyl] trimethylammonium chloride, diallyldimethylammonium chloride and n-vinylformamide.

4 . Papermaking agent system according to claim 1 , characterised in that the constituent a) and/or constituent b) is added to the cationic starch solution after the cooking of the starch mixture and the cationic groups are hydrolytically unstable.

5 . Papermaking agent system according to claim 1 , characterised in that the constituent c) is added before the cooking of the starch mixture and a part of the hydrolytically unstable cationic groups are hydrolysed into anionic groups during the cooking.

6 . Papermaking agent system according to claim 4 , characterised in that the hydrolytically unstable cationic groups originate from monomers selected from the group consisting of 2-(dimethylamino)ethyl acrylate, [2-(acryloyloxy)ethyl] trimethylammonium chloride, 2-dimethylaminoethyl methacrylate and [2-(methacryloyloxy)ethyl] trimethylammonium chloride.

7 . Papermaking agent system according to claim 5 , characterised in that the first polymer of constituent c) is a dispersion polymer, which is obtained by polymerising cationic polyacrylamide within an organic coagulant matrix.

8 . Papermaking agent system according to claim 1 , characterised in that the polymer composition comprises two or more constituents a), which have different chemical and/or physical characteristics.

9 . Papermaking agent system according to claim 1 , characterised in that the constituent b) contains two or more different first polymers and/or two or more different second polymers.

10 . Papermaking agent system according to claim 1 , characterised in that the third polymer of constituent c) comprises both hydrolytically unstable cationic groups and hydrolytically stable cationic groups

11 . Papermaking agent system according to claim 10 , characterised in that the constituent c) is a mixture of
at least one first third polymer, which comprises hydrolytically unstable cationic groups, and at least one second third polymer, which comprises hydrolytically stable cationic groups.

12 . Papermaking agent system according to claim 1 , characterised in that the polymer composition has a net charge of 0.5-5.5 meq/g, preferably 1-1.5 meq/g, at pH 7.

13 . Papermaking agent system according to claim 1 , characterised in that the anionic groups in constituents a) and/or b) have a net charge of at least −0.2 meq/g, preferably from −0.3 to −3.0 meq/g, more preferably from −0.4 to −1.5 meq/g, at pH 7.

14 . Papermaking agent system according to claim 1 , characterised in that the charge ratio of the cationic groups to the anionic groups in the constituent a) and/or the constituent b) is between 1.1:1 and 20:1, preferably between 1.3:1 and 10:1, more preferably between 1.5:1 and 3:1.

15 . Papermaking agent system according to claim 1 , characterised in that it comprises polymer composition in amount of 0.1-50 weight-%, preferably 0.1-30 weight-%, more preferably 0.2-15 weight-%, calculated from total amount of starch.

16 . Papermaking agent system according to claim 1 , characterised in that the polymer composition comprises 10-95 weight-%, preferably 15-90 weight-%, more preferably 20-80 weight-%, still more preferably 25-75 weight-%, of structural units derived from acrylamide and/or methacrylamide monomers, calculated from the total dry weight of the polymer composition.

17 . Papermaking agent system according to claim 1 , characterised in that the starch component in the starch mixture has
an amylopectin content in the range of 65-90%, preferably 70-85%, and an amylose content in the range of 10-35%, preferably 15-30%.

18 . Papermaking agent system according to claim 1 , characterised in that at least 70 weight-% of the starch units of the starch component in the starch mixture has an average molecular weight (MW) over 20 000 000 g/mol, preferably 50 000 000 g/mol, 100 000 000 g/mol.

19 . Papermaking agent system according to claim 1 , characterised in that starch component in the starch mixture has a degree of substitution (DS) in the range of 0.01-0.20, preferably 0.01-0.1, more preferably 0.015-0.06.

20 . Papermaking agent system according to claim 1 , characterised in that starch component has a charge density of 0.06-1.0 meq/g, preferably 0.06-0.56 meq/g, more preferably 0.09-0.35 meq/g.

21 . Use of a papermaking agent system according to claim 1 in papermaking or boardmaking for increasing the retention of starch to the formed web.

22 . Use according to claim 21 , characterised in that the papermaking agent system is added to the furnish before paper or board web formation, preferably to the thick stock.

23 . Method for making a papermaking agent system in liquid form, which comprises
(i) preparing a cationic starch solution by cooking a starch mixture, which comprises a starch component and a water component, and (ii) obtaining a polymer composition, which has anionic and cationic groups and which has net charge of >0.1 meq/g, preferably >0.5 meq/g, at pH 7, the polymer composition comprising or originating from at least one of constituents a), b) or c), where
constituent a) contains an amphoteric polymer, which is a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, and anionic and cationic groups attached to the copolymer,
constituent b) contains a first polymer, which is a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, and anionic or cationic groups attached to the copolymer, as well as
a second po

Assignees

• Kemira Oyj

Inventors

• Karppi Asko
• Hietaniemi Matti
• Polverari Marco

Classifications

• D21H21/06

  Paper forming aids · CPC title

• C08L3/08

  Ethers · CPC title

• C08B31/125

  having a substituent containing at least one nitrogen atom, e.g. cationic starch · CPC title

• D21H17/375

  Poly(meth)acrylamide · CPC title

• D21H21/20

  Wet strength agents · CPC title