Patent ID: 11883786
Assignee: ENTEGRIS, INC.
Field: Chemical engineering (Chemistry)
Classification: CPC B | IPC B

Claim 0:
1. An integral extruded porous polymeric sheet membrane comprising:
a first surface, a second surface, and a thickness between the first surface and the second surface,
a first thickness region that includes the first surface and a portion of the membrane in a direction of the thickness,
a second thickness region that includes the second surface and a portion of the membrane in a direction of the thickness, and
a third thickness region extending in the direction of the thickness between the first thickness region and the second thickness region,
wherein an average pore size of the first thickness region and an average pore size of the second thickness region are both less than an average pore size of the third thickness region, and wherein the membrane exhibits a retention of at least 90% measured using round polystyrene particles having a diameter of 5 to 15 nanometers.