METHOD FOR PREPARING DESALINATION MEMBRANES

专利名称：METHOD FOR PREPARING DESALINATION

MEMBRANES

发明人：ALLAN SHARPLES,WILLIAM BANKS申请号：US3439074D申请日：19651001公开号：US3439074A公开日：19690415

摘要：1,095,206. Cellulose ester films. ARTHUR D. LITTLE RESEARCH INSTITUTE. Feb.7, 1966 [Oct. 1, 1965], No. 5219/66. Heading B5B. A method of preparing a reverseosmosis membrane comprises dissolving a film-forming cellulose ester and a swellingagent in an organic solvent, casting the solution thus obtained to form a nim evaporatingat room temperature a portion of the organic solvent from the cast film, immersing thecast film in water to remove organic solvent, and heating the cast film in water. Preferablythe ester is cellulose acetate, but the acetyl group may be substituted by a suitable acylradical, e.g. the formyl, propionyl, or butyryl. The swelling agent may be an aqueoussolution of a perchlorate salt, e.g. magnesium perchlorate, or sodium perchlorate, or zincchloride or phenol, and the organic solvent may be acetone. Suitably, a portion of theorganic solvent is evaporated at an ambient temperature of at least 15‹ C. for about oneminute, and the cast film is heated in water at a temperature in the range of 60‹ to 80‹ C.,especially at about 73‹ C. for about 15 minutes. The cast film may be immersed in waterat from 0‹ C. to ambient temperature. In a preferred embodiment, a membrane suitablefor use in reverse osmosis demineralization processes is made by casting a solutionconsisting essentially of 22À2 parts by weight of cellulose acetate, 66À8 to 67À8 parts

acetone, 10 parts water, and about one to three parts of swelling agent to form a film,evaporating acetone from the film at a temperature of at least 15‹ C. for a period of from1-3 minutes, immersing the film in an aqueous bath consisting essentially of water at from0‹ C. to ambient temperature, and heating the film in an aqueous bath at a temperatureof 60-80‹ C. Alternatively, such a membrane may be made by casting a solution consistingessentially of 22À2 parts by weight of cellulose acetate, 66À8 parts acetone, 10 partswater and about 1 to 3 parts of swelling agent to form a film having a substantiallyuniform thickness up to about 0À01 inch, evaporating acetone from one surface of thefilm, at a temperature of at least 15‹ C. for a period of not more than about 1. minute,immersing the film in an aqueous bath consisting essentially of water at from 0‹ C. toambient temperature, and heating the film in an aqueous bath at a temperature of about70‹ to 75‹ C. In both embodiments, preferred swelling agents are magnesium perchlorateor zinc chloride, the film being immersed in water at a temperature of about 15‹ C., oralternatively at from 0‹ to 2‹ C., and the cast film then being heated in an aqueous bath at73‹ C. Examples are given.

申请人：ARTHUR D. LITTLE INC.,INTERIOR USA

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