| 摘要 |
<p>_ A process is provided for preparlng skinless hydrophilic alcohol-insoluble polyamide membranes by preparing a solution in a polyamide solvent of an alcohol-insoluble polyamide resin having a ratio CH2:NHCO of methylene CH2 to amide NHCO groups within the range from about 5:1 to about 7:1 inducing nucleation of the solution by controlled addition to the solution of a nonsolvent for the pplyamide resin, under controlled conditions of concentration, temperature, addition rate, and degree of agitation to obtain a visible precipitate of polyamide resin particles which may or may not thereafter partially or completely redissolve, thereby forming a casting solution; spreading the casting solution on a substrate to form a thin film thereof on the substrate; contacting and diluting the film of casting solution with a mixture of solvent and nonsolvent liquids containing a substantial proportion of the solvent liquid, but less than the proportion in the casting solution, thereby precipitating polyamide resin from the casting solution in the form of a thin skinless hydrophilic membrane; and washing and drying the resulting membrane; the alcohol-insoluble polyamide membranes obtained by this process have the unusual property of being hydrophilic, i. e., readily wetted by water, have absolute particle removal capabilities of the order of 0.1 to 5 .mu. M or more, and are useful as filter media, particularly for producing bacterially sterile filtrates.</p> |
