Patent ID: 11964032
Assignee: WANHUA CHEMICAL GROUP CO., LTD.
Field: Pharmaceuticals (Chemistry)
Classification: CPC A  C | IPC A  C

Claim 2:
3. The mask substrate composition according to claim 1, wherein (b) the aqueous polyurethane dispersion (b) is prepared according to a method comprising the following steps: mixing (b1) the polyisocyanate, (b2) the polyester polyol, (b3) the polyethylene glycol monomethyl ether, (b6) the polyhydroxyl chain extender and acetone at 50-100° C., performing a prepolymerization reaction, and dissolving the resulting prepolymer in an acetone solvent when the theoretical NCO content is reached or approached, in which the overall usage amount of acetone in the preparation process is 100-210 wt % of the mass of the polyurethane in (b) the aqueous polyurethane dispersion (b); after mixing the prepolymer and the acetone solvent, adding (b4) the polyamine chain extender (a′) and (b5) the polyamine chain extender (b′), continuing the reaction at 35-45° C. for 15-30 min, adding water under shear and dispersion conditions in which the usage amount of water is 100-170 wt % of the mass of the polyurethane in (b) the aqueous polyurethane dispersion (b), removing the acetone under vacuum, and obtaining (b) the aqueous polyurethane dispersion (b); and
the total solids content of (b) the aqueous polyurethane dispersion (b) is 30-50 wt %, and the particle size is 120 nm-190 nm.