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US 2026/0193844 A1Published application
Production of hydrophobic paper
AssigneeSca Forest Products AB
InventorsThomas NORDQVIST, Kent MALMGREN, Lars-Erik ENARSSON
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Abstract
A method of producing hydrophobic paper, using a sizing additive including a water-soluble chemically modified kraft lignin and a multivalent metal salt is described. Further described is a hydrophobic fiber-based product, such as a paper product obtainable by such method, and to the use of the sizing additive and metal salt in the production of hydrophobic fiber-based products, such as paper products.
Claims19
1:
- A method of producing a hydrophobic fiber-based product, comprising a step of adding
- (i) a sizing additive comprising a water-soluble chemically modified kraft lignin;
- and
- (ii) a multivalent metal salt;
- to a lignocellulosic pulp suspension at the wet end of a paper manufacturing process,
- wherein the water-soluble chemically modified kraft lignin at a concentration of 100 g/L has a soluble fraction of at least 90 wt % at neutral pH and room temperature,
- wherein the lignin has an average molecular weight of about 3000 g/mol to about 10000 g/mol, and
- wherein the water-soluble chemically modified kraft lignin of the sizing additive (i) is added in an amount of about 0.5 kg/t dry pulp to about 15 kg/t dry pulp.
5 more elements
2:
- The method according to claim 1, wherein the lignin has a charge density of ionic groups of at least 0.6 mmol/g as measured by polyelectrolyte titration at pH 7.
3:
- The method according to claim 1, wherein the lignin has an average molecular weight of at least about 4000 g/mol.
4:
- The method according to claim 1, wherein the water-soluble chemically modified kraft lignin of the sizing additive (i) is added in an amount of about 1 kg/t dry pulp to about 10 kg/t dry pulp.
5:
- The method according to claim 1, wherein the lignin is selected from the group consisting of dicarboxylic acid anhydride-modified kraft lignin, sulfonated kraft lignin, and oxidized kraft lignin.
6:
- The method according to claim 1, wherein the multivalent metal salt is at least one aluminum salt, at least one iron salt, or any mixture thereof.
7:
- The method according to claim 1, further comprising a step of adding a cationic polymer to a lignocellulosic pulp suspension at the wet end of a paper manufacturing process.
8:
- The method according to claim 7, wherein the cationic polymer is selected from cationic polysaccharides, polyethyleneimines, poly-diallyldimethylammonium chloride (polyDADMAC), polyamines and cationic polyacrylamides, and/or any combination thereof.
9:
- The method according to claim 1, further comprising a step of adding at least one further additive selected from dry-strength agents, wet-strength agents, enzymes, and/or any combination thereof.
10:
- The method according to claim 1, wherein the lignocellulosic pulp suspension is selected from a kraft pulp suspension, a recycled fiber pulp suspension, a suspension comprising a mixture of kraft pulp and recycled fibers, a suspension of bleached pulp, a mechanical pulp suspension, a semi chemical pulp suspension, a sulfite pulp suspension, a chemi-thermomechanical pulp suspension, and/or any combination thereof.
11:
- The method according to claim 1, wherein in carrying out the method, no alkenyl succinic anhydride (ASA), no alkyl ketone dimer (AKD) and no rosin is used.
12:
- A hydrophobic fiber-based product produced by the method according to claim 1.
13:
- The hydrophobic fiber-based product according to claim 12, wherein the hydrophobic fiber-based product has
- (i) a Cobb 60 value of 40 g/m2 or less as determined according to ISO 535;
- and/or
- (ii) a Cobb 1800 value of 100 g/m2 or less as determined according to ISO 535;
- and/or
- (iii) a Cobb 1800UV 48h value of 110 g/m2 or less as determined according to ISO 535.
3 more elements
14:
- The hydrophobic fiber-based product according to claim 12, wherein the hydrophobic fiber-based product is free of an ASA, an AKD, a rosin and any reaction product thereof.
15:
- A method comprising using water-soluble chemically modified kraft lignin having an average molecular weight of about 3000 g/mol to about 10000 g/mol, which at a concentration of 100 g/L has a soluble fraction of at least 90 wt % at neutral pH and room temperature as the sole sizing additive, together with a multivalent salt to produce a hydrophobic fiber-based product.
16:
- The method according to claim 1, wherein the lignin has an average molecular weight of about 3000 to about 10000 g/mol.
17:
- The method according to claim 5, wherein the lignin is dicarboxylic acid anhydride-modified kraft selected from kraft lignin modified with a cyclic acid anhydride selected from the group consisting of maleic anhydride;
- succinic anhydride;
- citraconic anhydride;
- itaconic anhydride;
- 2,3-dimethylmaleic anhydride;
- ethylsuccinic anhydride;
- 2,2 dimethylsuccinic anhydride;
- phthalic anhydride;
- quinolinic anhydride;
- diacetyl-tartaric anhydride;
- tetramethylsuccinic anhydride;
- diglycolic anhydride;
- and glutaric anhydride.
10 more elements
18:
- The method according to claim 6, wherein the multivalent metal salt is at least one aluminum salt selected from an aluminum chloride salt, an aluminum sulfate salt, or an iron salt selected from an iron(III) chloride, iron(III) sulfate, iron(III) nitrate, iron(III) citrate, and/or any combination thereof.
19:
- The method according to claim 7, wherein the cationic polymer is added in the form of a complex with the water-soluble chemically modified kraft lignin or wherein the cationic polymer is added separately from the water-soluble chemically modified kraft lignin at a different entry point.