ULTRAFILTRATION MEMBRANES AND METHODS OF MAKING

摘要

The present invention is an integral multilayered composite membrane having at least one ultrafiltration layer made by cocasting or sequentially casting a plurality of polymer solutions onto a support to form a multilayered liquid sheet and immersing the sheet into a liquid coagulation bath to effect phase separation and form a multilayered composite membrane having at least one ultrafiltration layer.

主权项

1. A process for forming a multilayered ultrafiltration membrane, said process comprising:
positioning a polymer solution applying apparatus having at least two dispensing outlets relative to a moving carrier surface; supplying each dispensing outlet with a different polymer solution, wherein a first polymer solution has a critical solution temperature and a second polymer solution has either no critical solution temperature or a higher critical solution temperature than the first polymer solution; applying the first and second polymer solutions with the polymer solution applying apparatus onto said moving carrier surface so as to create a multiple layer coating on said carrier surface, wherein said first and second polymer solutions are applied with essentially no time interval between successive polymer solutions being applied; and subjecting said multiple layer coating to two phase separation processes such that the first polymer solution forms a first layer due to a phase change caused by a change in the temperature outside of the critical solution temperature of the first polymer solution and the second polymer solution forms a second layer due to a phase change caused by either a change in the temperature outside of the critical solution temperature of the second polymer solution or immersion into a precipitation bath, so as to form a multilayer ultrafiltration membrane in which particles having a 20 to 100 nanometer (nm) diameter are retained.