METHOD OF PRODUCING POLYVINYL ACETALS

摘要

FIELD: chemistry.SUBSTANCE: described is a method of producing polyvinyl acetals, which involves reacting polyvinyl alcohol with an aldehyde or a mixture of aldehydes in an aqueous medium in the presence of an inorganic acid, followed by filtration of the obtained polyvinyl acetal dispersion, washing the filtered off polyvinyl acetal with distilled water, stabilisation thereof with aqueous sodium alkali solution and drying, the method being characterised by that the polyvinyl alcohol reacts with the aldehyde or mixture of aldehydes in molar ratio of 1:(0.2-1.0) and at temperature of 0-72°C; the filtered polyvinyl acetal is neutralised with 1.1-2.1 wt % aqueous ammonia solution at temperature of 15-25°C for 0.5-1.0 hours, washed 4-6 times with distilled water and stabilised at temperature of 40-60°C for 1-4 hours with 0.04-0.12 wt % aqueous sodium alkali solution or 0.04-0.40 wt % aqueous ammonia solution with liquor ratio at all steps of 5-8.EFFECT: reduced amount of washing water and obtaining polyvinyl acetal with minimal residual acidity and the required degree of acetalation.1 tbl, 30 ex