A process is provided for preparing skinless liquophilic alcohol-insoluble polyamide membranes by preparing at a first temperature a solution in a polyamide solvent having a temperature coefficient of solubility within the range from about 0.01 to about 5 weight per cent per degree Centrigrade of an alcohol-insoluble polyamide resin having a ratio CH2:NHCO of methylene CH2 to amide NHCO groups within the range from about 7:1 to about 12:1; inducing nucleation of the solution by controlled addition to the solution of a nonsolvent for the polyamide 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; cooling the film of casting solution to a second temperature sufficiently lower than the first temperature to precipitate polyamide resin from the casting solution; contacting and diluting the film of casting solution with a nonsolvent liquid, preferably containing a substantial proportion of the solvent liquid but less than the proportion in the casting solution, to precipitate polyamide resin from the casting solution in the form of a thin skinless liquophilic membrane; and washing and drying the resulting membrane; the alcohol-insoluble polyamide membranes obtained by this process have the unusual property of being liquophilic, i.e., readily wetted by organic liquids having a surface tension below about 60 dynesicm, while being substantially not wetted by water, have absolute particle removal capabilities of the order of 0.1 to 5 11M or more, and are useful as filter media for liquid systems in which such organic liquids are the continuous phase, as well as for separating immiscible liquid mixtures containing such liquids and liquids having a higher surface tension such as water.
本发明提供了一种用于制备无皮亲液性醇不溶性聚酰胺膜的工艺,其方法是在第一 温度下制备聚酰胺溶剂中的溶液,该溶液的溶解度温度系数在每摄氏度约 0.01至约5重量%/摄氏度的醇不溶性聚酰胺
树脂的溶液,其亚甲基
CH2与酰胺NHCO基团的 :NHCO比在约7:1至约12:在控制浓度、温度、添加速率和搅拌程度的条件下,向溶液中加入聚酰胺
树脂的非溶剂,诱导溶液成核,以获得聚酰胺
树脂颗粒的可见沉淀物,该沉淀物此后可能部分或完全再溶解,也可能不完全再溶解,从而形成浇铸溶液;将浇铸溶液涂抹在基底上,在基底上形成一层薄膜;将浇铸溶液薄膜冷却到比第一温度足够低的第二温度,以便从浇铸溶液中析出聚酰胺
树脂;将浇铸溶液薄膜与一种非溶剂液体接触并稀释,该非溶剂液体最好含有相当比例的溶剂液体,但小于浇铸溶液中的比例,以便从浇铸溶液中析出聚酰胺
树脂,形成一层薄的无皮嗜液膜;以及洗涤和干燥所得到的膜;通过该工艺得到的醇不溶性聚酰胺膜具有不寻常的嗜液特性,即.............e.,易被表面张力低于约 60 达因西克米的有机液体润湿,而基本上不被
水润湿,具有 0.1 至 5 11M 或更高数量级的绝对颗粒去除能力,可用作以此类有机液体为连续相的液体系统的过滤介质,也可用于分离含有此类液体和具有较高表面张力的液体(如
水)的不溶液体混合物。