METHOD FOR PRODUCTION OF POROUS MATERIAL Russian patent published in 1995 - IPC

FIELD: production of porous polymer materials. SUBSTANCE: porous material is produced by preparation of aqueous solution of polymer salt with its subsequent freezing up and removal of aqueous solvent. Aqueous solvent is removed without thawing out of frozen initial components. Then, polymer is treated with solution of acid or salt in organic solvent which does not dissolve polymer, with subsequent withdrawal of treating solution. Method is characterized by application of lyophilic drying or cryoextraction for withdrawal of treating solution. Polymer is treated with acid or salt in nondissolving medium or polymer wetting agent. After withdrawal of treating solution, polymer may be treated in various ways: drying without washing; washing without drying (storage in liquid medium), washing up to neutral reaction and drying. Method is applicable for most different, traditional for the purpose polymers: modofoed polyvinyl alcohol, sodium alginate, carboxy- methyl cellulose, dextran polymers, phosphocellulose, etc. Porous materials may be produced in various forms: in forms of sheets, plates, granules, spongy material, pipes, etc. In case of use of modified polyvinyl alcohol or dextran polymer, it is possible to combine stages of withdrawal of aqueous solvent by cryoextraction and treatment of polymer with modifying agent. EFFECT: higher efficiency. 7 cl