Method for preparing water polyurethane by solventless method

[0011] Example 1: Add 30.4g of polyester diol and 3g of dimethylolpropionic acid into a four-neck flask equipped with a thermometer, reflux condenser and mechanical stirring, heat to 110°C, and vacuum dehydration at this temperature for 30 minutes After cooling to 80°C, 16.6g of IPDI was added and reacted at 60°C for 4 hours. Subsequently, the temperature was lowered to 20° C., 112 ml of deionized water containing 2.24 g of triethylamine and 1.12 g of ethylenediamine was added under high-speed stirring, and then the temperature was raised to 60° C. for reaction for 1 hour. A polyurethane dispersion system with a solid content of 30% is obtained.

[0012] After the coating is dried, the breaking strength is 22.54MPa and the breaking elongation is 453.0%.

[0013] Example 2: Add 27.12g polyester diol, 6.78g polyether diol and 3g dimethylolpropionic acid into a four-neck flask equipped with a thermometer, reflux condenser and mechanical stirring, and heat to 110°C. After 30 minutes of vacuum dehydration at this temperature, it was cooled to 80°C, and 13.1 g of IPDI was added to react at 110°C for 4 hours. Subsequently, the temperature was lowered to 40° C., 134 ml of deionized water containing 2.26 g of triethylamine and 0.824 g of diethylene triamine were added under high-speed stirring, and then the temperature was raised to 60° C. for reaction for 1 hour. A polyurethane dispersion system with a solid content of 25% is obtained.

[0014] After the coating film is dried, the breaking strength is 16.82MPa and the breaking elongation is 574.9%.

[0015] Example 3: Add 23.12g polyester diol, 6.78g polyether diol, 0.18g 1,4 butanediol and 3g dimethylol in a four-neck flask equipped with thermometer, reflux condenser and mechanical stirring. Propionic acid was heated to 110°C, dehydrated under vacuum at this temperature for 30 minutes and then cooled to 80°C, 16.5g IPDI was added, and reacted at 110°C for 4 hours. Subsequently, the temperature was lowered to 40° C., deionized water 1361 in which 2.26 g of triethylamine and 0.824 g of diethylene triamine were dissolved was added under high-speed stirring, and then the temperature was raised to 60° C. for reaction for 1 hour. A polyurethane dispersion system with a solid content of 25% is obtained. After the coating is dried, the breaking strength is 19.25a and the breaking elongation is 549.9%.