Cationic copolymers derived from acrylamides and use thereof
A cationic copolymers of acrylamide obtained by the Hofmann rearrangement, using an alkali and/or alkaline earth hydroxide and an alkali and/or alkaline earth hypohalide, are provided. The copolymers can be used as strengthening agents for paper and/or coagulants. The copolymers have a desalination coefficient (Cd) higher than 0.6, higher than 0.65, or higher than 0.7.
1. A cationic copolymer obtained by Hofmann rearrangement in aqueous solution in the presence of an alkali and/or alkaline earth hydroxide and an alkali and/or alkaline earth hypohalide, on a base copolymer comprising:
at least 5 mole % of a non-ionic monomer selected from the group consisting of acrylamide; methacrylamide; N,N-dimethylacrylamide; acrylonitrile; and combinations thereof; and
at least one comonomer selected from the group consisting of unsaturated cationic ethylenic comonomer; non-ionic comonomer; and combinations thereof; and provided that the non-ionic comonomer is not acrylamide, methacrylamide, N,Ndimethylacrylamide, or acrylonitrile;
wherein the cationic copolymer obtained in aqueous solution has a desalination coefficient (Cd) of greater than 0.6, wherein
Cd
=
Real
polymeric
active
matter
(
in
weight
%
)
×
Polymer
filler
density
Conductivity
of
the
solution
containing
9
%
of
active
matter
.
2. The cationic copolymer according to claim 1 , wherein the alkali and/or alkaline earth hypohalide/non-ionic monomer ratio (alpha coefficient) is greater than 0.5.
3. The cationic copolymer according to claim 1 , wherein the alkali and/or alkaline earth hypohalide/non-ionic monomer ratio (alpha coefficient) is greater than 0.9.
4. The cationic copolymer according to claim 1 , wherein the cationic copolymer is produced in a concentration higher than 8% by weight.
5. The cationic copolymer according to claim 1 , wherein the cationic copolymer is produced in a concentration higher than 10% by weight.
6. The cationic copolymer according to claim 1 , wherein the cationic copolymer is produced in a concentration higher than 12% by weight.
7. The cationic copolymer according to claim 1 , wherein the base copolymer on which the Hofmann rearrangement is carried out has a molecular weight above 5000 g/mol.
8. The cationic copolymer according to claim 1 ,
wherein the unsaturated cationic ethylenic comonomer is selected from the group consisting of dialkylaminoalkyl(meth)acrylamide monomers, diallylamine monomers, methyldiallylamine monomers, and quaternary ammonium salts or acids thereof and
wherein the non-ionic comonomer is selected from the group consisting of N-vinyl acetamide, N-vinyl formamide, N-vinylpyrrolidone, vinyl acetate, and combinations thereof.
9. The cationic copolymer according to claim 8 ,
wherein the unsaturated cationic ethylenic comonomer is a quaternary ammonium salt or acid selected from the group consisting of dimethyldiallylammonium chloride (DADMAC), acrylamidopropyltrimethylammonium chloride (APTAC), and methacrylamidopropyltrimethylammonium chloride (MAPTAC).
10. The cationic copolymer according to claim 1 , wherein the base copolymer, on which the Hofmann rearrangement is conducted, comprises monomers comprising anionic fillers at a concentration of less than 5 mole % and comprises monomers of the acid or anhydride type selected from the group consisting of (meth)acrylic acid, acrylamidomethylpropane sulphonic acid, itaconic acid, maleic anhydride, maleic acid, methallyl sulphonic acid, vinyl-sulphonic acid, salts thereof, and combinations thereof.
11. The cationic copolymer according to claim 1 , wherein the base copolymer, on which the Hofmann rearrangement is conducted, is branched in the presence of a branching agent, and optionally in the presence of a transfer agent; and
wherein that the branching agent is selected from the group consisting of methylene bisacrylamide, ethylene glycol di-acrylate, polyethylene glycol dimethacrylate, diacrylamide, cyanomethylacrylate, vinyloxyethylacrylate, vinyloxyethylmethacrylate, triallylamine, formaldehyde, glyoxal, and a glycidylether type compound.
12. The cationic copolymer according to claim 11 , wherein the branching agent is a glycidylether type compound selected from the group consisting of ethyleneglycol diglycidylether, epoxies, and combinations thereof.
13. The cationic copolymer according to claim 1 , wherein the cationic polymer obtained has a cationic filler density higher than 3 meq/g.
14. The cationic copolymer according to claim 1 , wherein the aqueous solution comprising the base polymer further comprises at least one additive having a hydroxyl function, an amine function, or combinations thereof.
15. The cationic copolymer according to claim 14 , wherein the additive is selected from the group consisting of alcohols, polyols, polyosides, polyamines polyethylene imines, and combinations thereof.
16. The cationic copolymer according to claim 15 , wherein the polyol is starch.
17. The cationic copolymer according to claim 1 , wherein the cationic copolymer obtained in aqueous solution has a desalination coefficient (Cd) of greater than 0.65.
18. The cationic copolymer according to claim 1 , wherein the cationic copolymer obtained in aqueous solution has a desalination coefficient (Cd) of greater than 0.7.
19. A method for fabricating a sheet of paper, cardboard, or paper product, comprising
obtaining a fibrous suspension;
adding at least two dry strength agents to the fibrous suspension before the formation of the sheet, separately or in a mixture, in any order of introduction, and the two agents are added at one or more injection points; and
forming the sheet of paper, cardboard, or paper product;
wherein the at least two dry strength agents comprise a first agent and a second agent, and
the first agent is a cationic copolymer obtained by the Hofmann rearrangement of claim 1 , and
the second agent is a (co)polymer having an anionic filler density higher than 0.1 meq/g.
20. The method according to claim 19 , wherein the second agent is a (co)polymer comprising 1 to 100 molar % of at least one monomer having an anionic filler, and 0 to 99 molar % of at least one monomer having a neutral or cationic filler.
21. The method according to claim 20 , wherein the monomers having an anionic filler are monomers comprising:
at least one carboxylic function selected from the group consisting of acrylic acid, methacrylic acid, salts thereof, and combinations thereof;
at least one sulphonic acid function selected from the group consisting of 2-acrylamido-2-methylpropane sulphonique acid (AMPS), vinyl sulphonic acid, methallyl sulphonic acid, salts thereof, and combinations thereof;
at least one non-ionic monomer selected from the group consisting of acrylamide, methacrylamide, N,N dimethylacrylamide, N-vinyl pyrrolidone, N-vinyl acetamide, N-vinyl formamide, vinylacetate, acrylate esters, allyl alcohol, and combinations thereof;
at least one cationic monomer selected from the group consisting of dimethylaminoethyl acrylate (ADAME) quaternized or salified, dimethylaminoethyl methacrylate (MADAME) quaternized or salified, dimethyldiallylammonium chloride (DADMAC), acrylamido propyltrimethyl ammonium chloride (APTAC), methacrylamido propyltrimethyl ammonium chloride (MAPTAC), and combinations thereof; or
combinations thereof.
22. A method for strengthening paper or coagulant, comprising
adding a cationic copolymer obtained by the Hofmann rearrangement of claim 1 as a strengthening agent to the paper or coagulant.
23. A process for making a cationic copolymer comprising carrying out a Hofmann rearrangement in aqueous solution in the presence of an alkali and/or alkaline earth hydroxide and an alkali and/or alkaline earth hypohalide, on a base copolymer comprising:
at least 5 mole % of a non-ionic monomer selected from the group consisting of acrylamide; methacrylamide; N,N-dimethylacrylamide; acrylonitrile; and combinations thereof; and
at least one comonomer selected from the group consisting of unsaturated cationic ethylenic comonomer; non-ionic comonomer; and combinations thereof; and provided that the non-ionic comonomer is not acrylamide, methacrylamide, N,Ndimethylacrylamide, or acrylonitrile;
wherein the cationic copolymer obtained in aqueous solution has a desalination coefficient (Cd) of greater than 0.6, wherein
Cd
=
Real
polymeric
active
matter
(
in
weight
%
)
×
Polymer
filler
density
Conductivity
of
the
solution
containing
9
%
of
active
matter
.