The production and use of improved composite fluid separation membranes.

摘要

Prodn. of a multilayer composite membrane having an interior layer determining the gas or vapour sepn. characteristics of the membrane and an exterior layer protecting the sepn. layer from imperfections is by drying on a substrate a thin layer of a soln. comprising (A) up to 5 wt.% by vol. of a polymeric gas or vapour sepn. membrane forming material in a solvent system; and (B) up to 20 wt.% (based on wt. of membrane-forming material) of polysiloxane additive which forms the exterior protective layer.