Patent ID: 11958934
Assignee: SHIMU SPECIAL PROTECTIVE EQUIPMENT TECHNOLOGY (JIANGSU) CO., LTD.
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A method of preparing a waterborne polyurethane (WPU) emulsion, the WPU emulsion comprising the following raw materials in part by weight: 230-250 parts of polyol, 50-60 parts of isocyanate, 5-10 parts of a hydrophilic chain extender, 60-80 parts of a diluent, 5-9 parts of a neutralizer, 500-600 parts of water, 15-20 parts of a post chain extender, 0.01-0.05 parts of a catalyst, 3-7 parts of a cellulose thickener, 0.5-1.5 parts of a wetting agent, and 3-5 parts of a dispersant; and the method comprising the following steps:
step I: preparation of isocyanate terminated prepolymer
adding the polyol and the hydrophilic chain extender into a reactor, adding the isocyanate while stirring at 150-200 r/min, adding the catalyst after a temperature rises to 75-85° C., introducing nitrogen, and conducting heat preservation for 3 h to obtain the isocyanate terminated prepolymer;
step II: neutralization
when the temperature in the reactor is reduced to be no more than 60° C., adding the diluent and the neutralizer to neutralize the isocyanate terminated prepolymer to obtain a neutralized prepolymer;
step III: emulsification
at 20° C., adding the neutralized prepolymer in step II into the water to obtain a mixture, and stirring the mixture at 3,000-3,500 r/min for 30 min to form a dispersion;
step IV: post chain extension
at 450-500 r/min, adding the post chain extender to the dispersion in step III, and stirring for 30 min to obtain a WPU dispersion, wherein a particle size is limited to 20-30 μm during chain extension; and
step V: preparation of emulsion
adding the cellulose thickener, the wetting agent, and the dispersant into the WPU dispersion, and stirring for 30 min to obtain the WPU emulsion.