Patent ID: 9010545
Filing Date: 2015-04-21
Classification: B01D,C07K

Abstract:
1. A process for forming an integral, cocast multilayered composite ultrafiltration membrane comprising the steps of operatingly positioning a polymer solution applying apparatus having at least two dispensing outlets relative to a moving carrier surface, and; supplying each dispensing outlet with a different polymer solution wherein a first polymer solution is made with a polymer solution having a critical solution temperature and a second polymer solution is made with a polymer solution having a higher critical solution temperature than the first polymer solution and; 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, and wherein; said multiple layer coating is dispensed with essentially no time interval between successive layers being applied, and; subjecting said multiple liquid layers 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 for the first polymer solution and the second polymer solution forms a second layer due to a phase change caused by immersion into a precipitation bath for the second polymer solution so as to form a multilayer ultrafiltration membrane wherein the first layer is a skinned asymmetric ultrafiltration membrane layer, in which particles having a 20 to 100 nanometer (nm) diameter are retained, and the second layer is a microporous membrane layer, in which particles larger than 0.1 μm are retained.