US 11,655,331 B2
Method for preparing high-temperature self-crosslinking aqueous polyurethane dispersion
Ziao Wei, Shanghai (CN); and Yuchun Wei, Shanghai (CN)
Assigned to SHANGHAI SISHENG POLYMER MATERIALS CO., LTD., Shanghai (CN)
Filed by SHANGHAI SISHENG POLYMER MATERIALS CO., LTD., Shanghai (CN)
Filed on Dec. 1, 2020, as Appl. No. 17/108,688.
Claims priority of application No. 202010853878.5 (CN), filed on Aug. 24, 2020.
Prior Publication US 2022/0056194 A1, Feb. 24, 2022
Int. Cl. C08G 18/64 (2006.01); C08G 18/73 (2006.01); C08J 3/05 (2006.01); C09D 175/04 (2006.01)
CPC C08G 18/64 (2013.01) [C08G 18/73 (2013.01); C08J 3/05 (2013.01); C09D 175/04 (2013.01)] 7 Claims
 
1. A self-crosslinking aqueous polyurethane dispersion, including the following components:
20-40% by weight of a hydroxyl-containing polyurethane with blocked NCO groups;
60-80% by weight of deionized water;
0-8% by weight of an organic solvent; and
a pH regulator;
wherein, the hydroxyl-containing polyurethane with blocked NCO has a blocked NCO content of 1.8-5.0% and a hydroxyl content of 0.5-2.0% based on the dry solid portion;
wherein, the hydroxyl-containing polyurethane with blocked NCO is prepared by the following components:
30-50 parts by weight of a polymer polyol;
0.5-3 parts by weight of trimethylolpropane or trimethylolethane;
30-50 parts by weight of a isocyanate monomer;
3.0-6.0 parts by weight of 2,2-dimethylol propionic acid or 2,2-bis(hydroxymethyl)butyric acid;
5.0-15.0 parts by weight of a NCO blocking agent;
4.0-10.0 parts by weight of a hydroxyalkyl ethylenediamine chain extender;
0.01-0.05 parts by weight of a catalyst;
and wherein the self-crosslinking aqueous polyurethane dispersion is prepared by a method comprising:
(a) adding the polymer polyol, trimethylolpropane or trimethylolethane, isocyanate monomer, 2,2-dimethylol propionic acid or 2,2-bis(hydroxymethyl)butyric acid, catalyst and organic solvent to a reactor and reacting at 50-90° C. until the NCO content reaches or becomes less than a theoretical value to obtain a prepolymer, in which the isocyanate monomer is excessive;
(b) adding the NCO blocking agent to the prepolymer obtained in step (a) to partially block the NCO, and reacting at 50-90° C. until the NCO content reaches or becomes less than the theoretical value to obtain a polymer;
(c) cooling the polymers obtained in step (b) to 20-40° C., adding a pH regulator into the polymer, and then dispersing the polymer into the deionized water;
(d) then adding the hydroxyalkyl ethylenediamine chain extender, and reacting at 10-40° C. for 30 minutes; and
(e) in step (a), if the organic solvent added N-methyl-pyrrolidone, the solvent does not require to be separated; if the solvent added is acetone or butanone, the solvent needs to be separated by heating;
wherein a molar ratio of the blocked NCO to the hydroxyl groups introduced from the chain extender is 1:1 to 1.5:1.