US 12,291,622 B2
Method for preparing WPU synthetic leather foaming layers based on pickering foam template method
Chunhua Wang, Chengdu (CN); Wei Lin, Chengdu (CN); Ngai To, Chengdu (CN); Yifeng Sheng, Chengdu (CN); and Jianhui Wu, Chengdu (CN)
Assigned to Sichuan University, Chengdu (CN)
Filed by Sichuan University, Chengdu (CN)
Filed on Oct. 6, 2021, as Appl. No. 17/495,010.
Claims priority of application No. 202011443882.0 (CN), filed on Dec. 11, 2020.
Prior Publication US 2022/0185984 A1, Jun. 16, 2022
Int. Cl. C08J 9/28 (2006.01); C08G 18/08 (2006.01); C08G 18/12 (2006.01); C08G 18/32 (2006.01); C08G 18/34 (2006.01); C08G 18/48 (2006.01); C08G 18/66 (2006.01); C08G 18/75 (2006.01); C08J 9/00 (2006.01); D06N 3/00 (2006.01); D06N 3/14 (2006.01)
CPC C08J 9/286 (2013.01) [C08G 18/12 (2013.01); C08G 18/14 (2013.01); C08G 18/3206 (2013.01); C08G 18/348 (2013.01); C08G 18/4854 (2013.01); C08G 18/6607 (2013.01); C08G 18/6692 (2013.01); C08G 18/755 (2013.01); C08J 9/0066 (2013.01); D06N 3/0043 (2013.01); D06N 3/148 (2013.01); C08J 2375/08 (2013.01); D06N 2205/04 (2013.01)] 5 Claims
 
1. A method for preparing a waterborne polyurethane synthetic leather foaming layer based on a Pickering foam template method, comprising the following steps:
(1) selecting a soft waterborne polyurethane with a solid content of 20-40% as a raw material for the waterborne polyurethane synthetic leather foaming layer, adding a waterborne crosslinking agent thereto, and mixing uniformly to obtain a waterborne polyurethane slurry for synthetic leather;
(2) adding the waterborne polyurethane slurry for synthetic leather to an open container, then adding hydrophobic inorganic solid particles that can be adsorbed at a water-air interface as a foam stabilizer, wherein a mass ratio of the hydrophobic inorganic solid particles to the waterborne polyurethane slurry for synthetic leather is (0.05-0.2): 1, a volume of a mixed solution in the container is below ½ of a volume of the container, and air is used as a dispersed phase; after mixing uniformly, performing emulsifying and dispersing by a high-speed emulsifier for 0.5-2 h with a speed of 8000-15000 rpm/min to obtain a Pickering waterborne foam slurry containing polyurethane latex particles; and
(3) drying the Pickering waterborne foam slurry at 70-120° C. to obtain the waterborne polyurethane synthetic leather foaming layer based on the Pickering foam template method;
wherein the waterborne polyurethane slurry for synthetic leather is prepared by the following steps:
1) adding a hard segment monomer diisocyanate and a soft segment monomer polymer diol to a reactor in accordance with a molar ratio of (2-5):1, adding an appropriate amount of solvent acetone, and stirring and reacting for 1 h at a temperature of 60-90° C.; then adding a chain extender 2,2-dimethylolpropionic acid and 1,4-butanediol and 1-2 drops of a catalyst with a molar ratio of the chain extender to the soft segment monomer polymer diol of (1-4): 1, and conducting a reaction at a temperature of 70-90° C. for 3-6 h with a stirring speed of 100-2000 rpm to obtain a polyurethane polymer; wherein a ratio of the 2,2-dimethylolpropionic acid to the 1,4-butanediol is adjusted to make an amount of the 2,2-dimethylolpropionic acid account for 4-6 wt % of all reactants added;
2) adding triethylamine to the reactor, performing neutralization for 0.5-2 h at a temperature of 40-50° C. and a stirring speed of 1000-2000 rpm, adjusting a pH to 3-10; finally adding a certain amount of deionized water to a resulting reaction product, stirring for 10-30 min at a stirring speed of 8000-10000 rpm; and stirring for 1-2 h at a stirring speed of 1000-3000 rpm; and
3) removing acetone by rotary evaporation, and concentrating a resulting product to a solid content of 20%-40% to obtain the waterborne polyurethane slurry for synthetic leather.