▎ 摘　　要

NOVELTY - Polyurethane pre-polymer comprises 12-24 pts. wt. polyisocyanate and 20-40 pts. wt. polyether glycol. USE - The polyurethane pre-polymer is useful for medical dressing. ADVANTAGE - The polyurethane prepolymer has good anti-aging performance, antibacterial property and water absorption property. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a preparation method of polyurethane prepolymer for medical dressing, which involves (i) mixing deionized water and aminated lignin with mass of 9.8-10.2 times, subjecting to ultrasonic for 20-30 min under the 24-26 degrees Celsius and 20 kHz ultrasonic condition, then adding 20 wt.% sodium hydroxide solution, adjusting pH to 11-12, stirring for 5min at 200-300r/min rotating speed, then under the protection of nitrogen, the temperature is 90-120 degreesC and 200-300r/min stirring condition, dripping amination lignin with mass of 1.1-1.3 times of propylene oxide at a dripping speed of 60-80 drops/min, keeping the temperature and refluxing for 3-4h at 10 Pascal vacuum, dehydrating for 2h under the condition of 110-120 degrees Celsius to obtain the polyether polyol; (ii) stirring the modified polyisocyanate monomer at the rotating speed of 300-500r/min for 10-15 min under the protection of nitrogen, heating to 70 degrees Celsius, then dropping the modified polyisocyanate monomer at the dropping speed of 80-100 drops/min, after finishing dripping, continuously maintaining the temperature and stirring, when the isocyanate content is reduced to 30-40 %, adding modified polyisocyanate monomer with mass 0.01 times of benzoyl chloride, continuously stirring for 0.5h, cooling to room temperature to obtain the polyisocyanate; and (iii) under the stirring condition of 70-90 degrees Celsius and 300-600r/min rotating speed, dropping the polyether polyol with mass of 0.85-0.95 times of diethylenetriamine and polyether polyol with mass of 0.58-0.62 times of polyisocyanate to the polyether polyol at a dropping speed of 40-60 drops/min, maintaining the temperature and stirring for 3h, reducing the temperature to 50 degrees Celsius to obtain the polyurethane prepolymer.