ULTRA-FILTRATING HEAT AND CHEMICAL RESISTANT POLYIMIDE MEMBRANE AND METHOD OF ITS Russian patent published in 2008 - IPC B01D71/64 B01D63/02 B01D61/18 B01D67/00 B01D35/16 B01D46/54 

FIELD: technological processes.

SUBSTANCE: invention concerns obtaining ultrafiltration ultraporous polyimide membranes resistant to heat and chemicals and can be applied in membrane technologies, particularly at temperatures over 200°C and in aggressive media. Membrane has a form of porous film or hollow fiber with anisotropic structure, including selective layer and substrate. Ultraporous selective surface layer with 70-800 A⁰ pore size and 0.1-10 mcm thickness consists of insoluble rigid-chain aromatic (co)polyimide based on aromatic tetracarboxylic acid dianhydride and aromatic diamine, and is placed on microporous substrate made of the same polymer of 50-250 mcm thickness. The membrane features water permeability Q=(2-500)·10^-4 cm/sec under atmospheric pressure and rated molecular detention weight M_L=(5-500)·10³ g/mol. Method of obtaining the membrane involves preparation of 10-15% forming solution of (co)polyamide acid based on aromatic tetracarboxylic acid dianhydride and aromatic diamine in amide solvent; stirring; decontamination. Solution of polyimidoamide acid imidised by 20-40% is poured through spinneret with adjustable clearance onto the forming plate. Then the plate is submerged into water or water-alcohol settlement tank. Formed membrane is held in 20-60% high-boiling industrial oil solution in organic solvent to fill membrane pores with oil, dried and heated to 150-200°C at temperature growth rate of 10 degrees per minute till complete (co)polyimidoamide acid imidisation. Membrane operation temperature reaches 300-400°C. Membranes preserve their properties in aggressive media and organic solvents.

EFFECT: obtaining of ultrafiltration ultraporous polyimide membranes resistant to heat and chemicals.

15 cl, 21 ex