Polyolefin material having a low density
AssigneeKimberly-Clark Worldwide, Inc.
InventorsVasily A. Topolkaraev, Ryan J. McEneany, Antonio J. Carrillo
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Abstract
A polyolefin material that is formed by solid state drawing of a thermoplastic composition containing a continuous phase that includes a polyolefin matrix polymer and nanoinclusion additive is provided. The nanoinclusion additive is dispersed within the continuous phase as discrete nano-scale phase domains. When drawn, the nano-scale phase domains are able to interact with the matrix in a unique manner to create a network of nanopores.
Claims31
A polyolefin material that is formed by drawing of a thermoplastic composition, wherein the thermoplastic composition contains a continuous phase that includes a polyolefin matrix polymer and a polymeric nanoinclusion additive and a polymeric microinclusion additive dispersed within the continuous phase in the form of discrete domains,
- wherein the polymeric nanoinclusion additive is in the form of nano-scale domains and the polymeric microinclusion additive is in the form of micro-scale domains,
- wherein the polymeric nanoinclusion additive constitutes from about 0.05 wt % to about 20 wt. % of the composition, based on the weight of the continuous phase;
- and
- wherein the polymeric microinclusion additive constitutes from about 1 wt % to about 20 wt % of the composition, based on the weight of the continuous phase;
- wherein a porous network is defined in the drawn thermoplastic composition that includes a plurality of micropores, and a plurality of nanopores adjacent to the nano-scale domains and/or the micro-scale domains, the nanopores having an average cross-sectional dimension of about 800 nanometers or less, the drawn thermoplastic composition having a density of about 0.90 g/cm3 or less;
- wherein the polyolefin material exhibits a hydrohead value of about 50 centimeters or more and a water vapor transmission rate of about 300 g/m2-24 hours or more.
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 a polymeric nanoinclusion additive and a polymeric microinclusion additive dispersed within the continuous phase in the form of discrete domains, wherein the polymeric nanoinclusion additive is in the form of nano-scale domains and the polymeric microinclusion additive is in the form of micro-scale domains, wherein the polymeric nanoinclusion additive constitutes from about 0.05 wt % to about 20 wt. % of the composition, based on the weight of the continuous phase, and the polymeric microinclusion additive constitutes from about 1 wt % to about 20 wt % of the composition, based on the weight of the continuous phase;
- and
- solid state drawing the thermoplastic composition, wherein a porous network is defined in the drawn thermoplastic composition that includes a plurality of micropores, and a plurality of nanopores adjacent to the nano-scale domains and/or the micro-scale domains, the nanopores having an average cross-sectional dimension of about 800 nanometers or less, the drawn thermoplastic composition having a density of about 0.90 g/cm3or less;
- wherein the polyolefin material exhibits a hydrohead value of about 50 centimeters or more and a water vapor transmission rate of about 300 g/m2-24 hours or more.
Dependencies are inferred from the claim text.