Membranes with integrated drainage prepn. for filtration - by filling pores in flat polyolefin article with liq., coating with soln. of polyamide membrane polymer, and converting layer into membrane

摘要

Prepn. comprises (1) partly or completely filling hollow of a flat porous shaped article (I) for drainage purposes with a liq. (II), (2) coating (I) with casting soln. contg. a membrane polymer (III), and (3) converting layer of casting soln. into a membrane by phase inversion. Membranes are prepd. by above process. Pref. (I) is nonwoven fabric, esp. polyolefin, polyamide, or polyester. (II) is pptn. agent for (III). (II) is water, esp. contg. wetting agent. Hollow spaces are filled by applying layer of (II) on solid support and laying (III) on the support. Support is a drum in the pptn. bath, and layer of (II) is applied by rotation of drum. (I) is coated with casting soln. in 2 stages, esp. with casting solns. of different compsn. and/or with different (III). Process is continuous. (III) is polysulphone, polyamide, polyether sulphone, cellulose deriv., or fluoro-polymer soln. in organic solvents. Phase inversion comprises immersing coated (I) in pptn. bath. USE/ADVANTAGE - Ultra- or micro-filtration or as microporous adsorber. Depth of penetration of casting soln. in (I) can be regulated without having to effect viscosity of casting soln.; membranes reinforced on one side can be prepd., reinforcement also used as drainage.