High cationic starch as a promoter in AKD sizing emulsions
AssigneeKemira Oyj
InventorsJennifer Riser, Kirsi Terava, Timo Valkealaakso, Jaakko Hiltunen
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Abstract
A method for preparation of a starch-promoted alkyl ketene dimer (AKD) sizing emulsion is provided. The inventive method comprises adding a sizing promoter comprising high-charge cationic starch and polyaluminum chloride (PAC) to a stabilized AKD emulsion and further wherein addition of said sizing promoter comprising high-charge cationic starch and PAC is effected at ambient temperature, after emulsification, stabilization, and homogenization of said stabilized AKD emulsion; and prior to addition of the starch-promoted AKD sizing emulsion to papermaking furnish, pulp, or fiber stock.
Claims9
A method for preparation of a starch-promoted alkyl ketene dimer (AKD) sizing emulsion for the manufacture of paper or board, wherein the method comprises adding to a stabilized AKD emulsion comprising a cationic starch stabilizing agent:
- (a) a cationic starch sizing promoter, and
- (b) polyaluminum chloride (PAC)
- wherein addition of said cationic starch sizing promoter and PAC is effected
- (i) at temperature ranging from 22-27° C.;
- (ii) after emulsification, stabilization, and homogenization of said stabilized AKD emulsion comprising the cationic starch stabilizing agent;
- and
- (iii) prior to addition of the starch-promoted AKD sizing emulsion to papermaking furnish, pulp, or fiber stock,
- wherein the high-charge cationic starch sizing promoter comprises a percent nitrogen (% N) content ranging from 0.5% to 1.6% by mass.
A method for preparation of a starch-promoted alkyl ketene dimer (AKD) sizing emulsion for the manufacture of paper or board, wherein the method comprises:
- (a) forming a cationic starch stabilizing agent by steam cooking or pot-cooking a cationic starch to form an aqueous starch solution;
- (b) adding to said cationic starch stabilizing agent a hydrophobic internal sizing agent comprising AKD wax pellets and/or molten AKD and agitating to form a thoroughly homogenized emulsion;
- (c) diluting said homogenized emulsion with water, optionally treating with additional cationic polymer stabilizing agents, agitating to form a homogenized emulsion, and cooling to 22-27° C. to form a stabilized AKD emulsion;
- (d) treating said stabilized AKD emulsion at temperature ranging from 22-27° C. with a sizing promoter comprising a cationic starch comprising a percent nitrogen (% N) content ranging from 0.5% to 1.6% by mass to obtain a final starch dosage ranging from 1% to 7%, by weight on AKD while agitating at a rate of 5000 rpm for a duration of 30 seconds followed by agitating until thoroughly incorporated;
- and
- (e) treating said thoroughly incorporated emulsion with an aqueous solution of PAC to obtain a final PAC dosage ranging from 2% to 20%, 5% to 16%, or 12% to 14% by weight on AKD and thoroughly incorporating to form a starch-promoted AKD sizing emulsion.
Dependencies are inferred from the claim text.