POROUS POLYVINYLFORMAL PREPARATION METHOD Russian patent published in 2007 - IPC A61L15/16 

FIELD: medical-destination sorbents.

SUBSTANCE: invention relates to manufacturing of medicinal sorption nonwoven materials, in particular, polyvinylformal-based hydrophilic foamed materials. Preparation procedure comprises chemical modification of aqueous solution of polyvinyl alcohol with cross-linking agent in presence of mineral acid. More specifically, 5-20% polyvinylformal aqueous solution is first heated to 80-90°C at constant mechanical stirring, after which cold aqueous starch solution is added and resulting mixture is cooled to 30-40°C while continuing stirring for further 25-30 min. To thus obtained solution, aqueous formalin solution (cross-linking agent) and, 20-30 min later, sulfuric acid are added. Resulting polymer mass is poured into mold and held therein at 50-70°C for 6 h. Molded mixture with acquired cellular structure is removed from mold, rinsed, and dried at 25-30°C.

EFFECT: simplified preparation technology due to eliminated foaming agent and sodium chloride, increased hydrophilicity of material, and strengthened more uniform close-meshed structure.