METHOD OF PURIFYING POLYCAPROLACTONE FROM TIN IMPURITIES Russian patent published in 2024 - IPC C08G63/90 C08G63/08 

FIELD: chemical or physical processes.

SUBSTANCE: invention relates to polymer synthesis, specifically to removal of organic tin compounds from polycaprolactone used to make medical devices in contact with blood, in order to avoid toxicological effect of tin on the human body during their bioresorption. Method of purifying polycaprolactone from tin impurities is characterized by that polycaprolactone is added to an alkali metal chloride solution with concentration of 36 wt.% with volume ratio of polycaprolactone to alkali metal chloride solution of 1:5. By heating the obtained mixture to 80°C while stirring with an overhead turbine mixer at rate of 500 rpm, polycaprolactone is melted. Further, the stirring speed is increased to 1,500 rpm and extraction is carried out for 15 minutes, then the liquid part is cooled and decanted. Remaining mass is washed with water at a volume ratio of 1:5 and temperature of 80°C while stirring at rate of 1,500 rpm for 15 minutes, cooled to room temperature and the liquid portion is decanted. Then propanol-1 is added at volume ratio of 1:2 and stirred at rate of 1,000 rpm for 5 minutes, the mixture is settled, liquid part is drained by decantation and the purified polymer mass is dried under vacuum conditions at 50°C and residual pressure of 7 mbar. Alkali metal chloride solution used is a sodium chloride solution or a potassium chloride solution.

EFFECT: reduction of extraction time to 15 minutes, reduction of process temperature.

3 cl, 2 ex