Hydrophilic microporous membrane

DETAILED DESCRIPTION The present invention relates to a polymeric membrane having controlled pore size that is prepared in an oil in water system where the water is the continuous phase and the oil phase contains the polymer.
A pore forming agent is incorporated into the system.
If the pore forming agent is a liquid it is incorporated into the discontinuous phase (oil phase).
If the pore forming agent is a normally solid water soluble inorganic salt it is dissolved in the continuous phase.
The system is heated to evaporate the continuous phase and concentrate the discontinuous polymer containing phase so that crosslinking takes place.
By varying the ionic strength of the pore forming agent one can effect the surface tension between the droplets or the discontinuous phase and the continuous phase.
This results in controlled porosity.
The hydrophilic membranes produced in accordance with the present invention can be used in a variety of applications.
For example, they can be used with or without a support and placed at the mouth end of a cigarette rod or in a pipe or cigarette holder to separate tar, carbon monoxide and other toxic components from tobacco smoke.
The hydrophilic membranes of the present invention can also be used in various oil-water separation processes where the major constituent of the liquid being treated is water.