RU2000129365A - POROUS ACETATE CELLULOSE MEMBRANE ON A SUBSTRATE AND METHOD FOR PRODUCING IT - Google Patents

Claims (5)

1. A porous cellulose acetate membrane on a substrate containing a porous lavsan-based substrate and a layer of a mixture of cellulose acetate polymers having a different proportion of bound acetic acid connected to it, characterized in that the substrate is made of lavsan paper with an average pore size of 0.5-10.0 microns and a thickness of 45.0 - 120.0 microns, the substrate is completely impregnated with a porous cellulose acetate polymer having an average pore size of 0.01 - 0.45 microns and consisting of a mixture of 1: 1 by weight cellulose acetate containing 54.6- 55.2 wt. % bound acetic acid and not more than 7.0 wt. % low molecular weight fractions, and cellulose acetate containing 57.0-57.5 wt. % bound acetic acid and not more than 7.0 wt. % low molecular weight fractions
and at the same time, the substrate and the polymer are impregnated with glycerin uniformly distributed in their pores in the amount of 50.0 - 80.0 wt. hours to 100.0 wt. including polymer.  2. The porous cellulose acetate membrane according to claim 1, characterized in that its substrate is impregnated with a porous polymer having an average pore size, in microns: 00.1 - 0.03 or 0.03 - 0.05, or 0.05 - 0 , 1, or 0.1 - 0.15, or 0.15 - 0.25, or 0.25 - 0.45. 3. A method of obtaining a porous cellulose acetate membrane on a substrate by dissolving cellulose acetate in an organic solvent to form a solution, molding the solution into a membrane on a porous substrate and heat treating the formed membrane at an elevated temperature, characterized in that polyester paper with an average pore size of 0 is taken as a substrate 5-10.0 microns and a thickness of 45.0-120.0 microns; as cellulose acetate take a mixture of 1: 1 by weight, consisting of cellulose acetate containing 54.6-55.2 wt. % bound acetic acid, not more than 7.0 wt. % low molecular weight fractions, and not more than 3.5 wt. % water and cellulose acetate containing 57.0-57.5 wt. % bound acetic acid and not more than 7.0 wt. % low molecular weight fractions, and not more than 3.0 wt. % water;
as an organic solvent, take a mixture of methylene chloride and isopropyl alcohol in a volume ratio (3-6): 1; cellulose acetate solution before molding into the membrane is additionally structured by a system consisting of a mixture of vol. hours:
Methylene Chloride - 1
Isopropyl alcohol - 3.3 - 7.5
Glycerin - 0.6 - 7.5
Desalted water - 0.35 - 1.0
and the formation of the membrane and its heat treatment are carried out simultaneously under conditions of free evaporation of solvents and, at least, in three stages, at which the temperature increasing from stage to stage and the same absolute humidity are maintained in the range of not more than 5.0 g / m ³ . 4. A method of obtaining a porous cellulose acetate membrane according to claim 3, characterized in that at the first stage of molding and heat treatment maintain a temperature of 20 ± 5 ^o C for 0.5 to 1.0 minutes, at the 2nd stage - 20 - 30 ^o C for 1.0 - 2.0 minutes, at the 3rd stage - 30 - 40 ^o C for 2.0 - 3.0 minutes 5. A method of obtaining a porous cellulose acetate membrane according to paragraphs. 3 and 4, characterized in that the structuring of the solution of cellulose acetate is carried out by slow for 20-30 minutes, with stirring and a temperature of 20 ± 5 ^o With adding to this solution in an amount of 3.5 to 7.0 wt. hours to 1.0 wt. including a mixture of cellulose acetates structuring system consisting of a mixture of methylene chloride, isopropyl alcohol, glycerol and water; heating the resulting mixture of solution and structuring system to a temperature of 33 ± 5 ^o C, holding at this temperature and stirring for 0.5-1.0 hours, and subsequent filtration and deaeration.