Method for producing paper, paperboard and cardboard having high dry strength
View Patent ↗Process for the production of paper, board and cardboard having high dry strength by addition of an aqueous composition comprising a nanocellulose and at least one polymer selected from the group consisting of the anionic polymers and water-soluble cationic polymers, draining of the paper stock and drying of the paper products.
1. A process for the production of paper, board, and cardboard having high dry strength, the process comprising:
(I) metering into a paper stock an aqueous composition comprising a nanocellulose comprising cellulose fibers and at least one anionic polymer and optionally a water-soluble cationic polymer;
(II) draining the paper stock, to obtain paper product; and
(III) drying the paper product;
wherein the anionic polymer comprises, as polymerized units:
(a) at least one monomer selected from the group consisting of a C 1 - to C 20 -alkyl acrylate, a C 1 - to C 20 -alkyl methacrylate, a vinyl ester of a saturated carboxylic acid comprising up to 20 carbon atoms, a vinylaromatic comprising up to 20 carbon atoms, an ethylenically unsaturated nitrile, a vinyl ester of a saturated, monohydric alcohol comprising 1 to 10 carbon atoms, a vinyl halide, and an aliphatic hydrocarbon comprising 2 to 8 carbon atoms and one or two double bonds;
(b) at least one anionic monomer selected from the group consisting of an ethylenically unsaturated C 3 - to C 8 -carboxylic acid, a vinylsulfonic acid, acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, vinylphosphonic acid, and salts thereof;
(c) optionally, at least one monomer selected from the group consisting of a C 1 - to C 10 -hydroxyalkyl acrylate, a C 1 - to C 10 -hydroxyalkyl methacrylate, acrylamide, methacrylamide, an N—C 1 - to C 20 -alkylacrylamide, and an N—C 1 - to C 20 -alkylmethacrylamide; and
(d) optionally, a monomer comprising at least two ethylenically unsaturated double bonds in the molecule.
2. The process of claim 1 , wherein the nanocellulose has a length dimension below 1000 μm and a fiber thickness in a range from 50 μm to 3 nm.
3. The process of claim 2 , wherein at least 80% of the cellulose fibers of the nanocellulose have a fiber thickness in a range from 50 μm to 3 nm.
4. The process of claim 3 , wherein at least 80% of the cellulose fibers of the nanocellulose have a fiber thickness in a range from 1 μm to 5 nm.
5. The process of claim 1 , wherein the nanocellulose has a length dimension below 1000 μm a fiber thickness in a range from 50 μm to 3 nm, and
wherein the nanocellulose further comprises from 5 ppm to 2% by weight of an ionic fluid, based on a total mass of the nanocellulose.
6. The process of claim 5 , wherein at least 80% of the cellulose fibers of the nanocellulose have a fiber thickness of from 50 μM to 3 nm and comprise from 5 ppm to 2% by weight of an ionic liquid, based on a total mass of the nanocellulose.
7. The process of claim 1 , wherein the anionic polymer comprises, as polymerized units:
(c) at least 60 mol % of at least one monomer selected from the group consisting of a C 1 - to C 20 -alkyl acrylate, a C 1 - to C 20 -alkyl methacrylate, vinyl acetate, vinyl propionate, styrene, α-methylstyrene, p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, acrylonitrile, methacrylonitrile, butadiene, and isoprene; and
(d) from 0.5 to 9 mol % of an ethylenically unsaturated C 3 - to C 5 -carboxylic acid.
8. The process of claim 1 , wherein the anionic polymer comprises, as polymerized units, at least 80 mol % of a monomer of group (a).
9. The process of claim 1 , wherein the anionic polymer comprises, as monomer of group (a), a mixture comprising, as polymerized units:
(i) at least one selected from the group consisting of a C 1 - to C 20 -alkyl acrylate and a C 1 - to C 20 -alkyl methacrylate; and
(ii) at least one selected from the group consisting of styrene, α-methylstyrene, p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, butadiene and isoprene,
wherein a weight ratio of (i) to (ii) is from 10:90 to 90:10, based on a total weight of the mixture.
10. The process of claim 1 , wherein a molar mass M w of the cationic polymer is in the range from 5000 to 5 million g/mol.
11. The process of claim 1 , wherein a charge density of the cationic polymer is in a range from 0.5 to 23 meq/g.
12. The process of claim 1 , wherein the water-soluble cationic polymer comprises a polymer comprising a vinylamine unit.
13. The process of claim 2 , wherein the nanocellulose has a length dimension in a range from 100 nm to 500 μm and a fiber thickness in a range from 1 μm to 5 nm.
14. The process of claim 2 , wherein the nanocellulose has a length dimension in a range from 100 nm to 100 μm and a fiber thickness in a range from 1 μm to 5 nm.
15. The process of claim 2 , wherein the nanocellulose has a length dimension in a range from 100 nm to 50 μm and a fiber thickness in a range from 1 μm to 5 nm.
16. The process of claim 2 , wherein the nanocellulose has a length dimension in a range from 100 nm to 10 μm and a fiber thickness in a range from 1 μm to 5 nm.
17. An aqueous composition, comprising:
a nanocellulose comprising cellulose fibers, wherein at least 80% of the cellulose fibers have a fiber thickness of from 50 μm to 3 nm, and from 5 ppm to 2% by weight of an ionic liquid, based on a total mass of the nanocellulose;
at least one anionic polymer; and
optionally, a water-soluble cationic polymer;
wherein the anionic polymer comprises, as polymerized units:
(a) at least one monomer selected from the group consisting of a C 1 - to C 20 -alkyl acrylate, a C 1 - to C 20 -alkyl methacrylate, a vinyl ester of a saturated carboxylic acid comprising up to 20 carbon atoms, a vinylaromatic comprising up to 20 carbon atoms, an ethylenically unsaturated nitrile, a vinyl ester of a saturated, monohydric alcohol comprising 1 to 10 carbon atoms, a vinyl halide, and an aliphatic hydrocarbon comprising 2 to 8 carbon atoms and one or two double bonds;
(b) at least one anionic monomer selected from the group consisting of an ethylenically unsaturated C 3 - to C 8 -carboxylic acid, a vinylsulfonic acid, acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, vinylphosphonic acid, and salts thereof;
(c) optionally, at least one monomer selected from the group consisting of a C 1 - to C 10 -hydroxyalkyl acrylate, a C 1 - to C 10 -hydroxyalkyl methacrylate, acrylamide, methacrylamide, an N—C 1 - to C 20 -alkylacrylamide, and an N—C 1 - to C 20 -alkylmethacrylamide; and
(d) optionally, a monomer comprising at least two ethylenically unsaturated double bonds in the molecule.