Patent ID: 11965083
Assignee: KIMBERLY-CLARK WORLDWIDE, INC.
Field: Other special machines (Mechanical engineering)
Classification: CPC B  C | IPC B  C

Claim 21:
22. A method for forming a polyolefin material, the method comprising:
forming a thermoplastic composition that contains
a continuous phase that includes a polyolefin matrix polymer and
from about 1 wt. % to about 20 wt. %, based on the weight of the continuous phase, of a polymeric microinclusion additive dispersed within the continuous phase in the form of discrete domains;
from about 0.05 wt. % to about 20 wt. % based on the weight of the continuous phase, of a polymeric nanoinclusion additive dispersed within the continuous phase in the form of discrete domains; and

solid state drawing the thermoplastic composition, wherein a porous network is defined in the composition that includes a plurality of nanopores having an average cross-sectional dimension of about 800 nanometers or less and a plurality of micropores having an aspect ratio of an axial dimension to a cross-sectional dimension of about 1 to about 30, the composition having a density of about 0.90 g/cm3 or less; and
wherein the polyolefin material exhibits a hydrohead value of about 50 centimeters or more.