Surface Free Energy Based Filled Polymer Microporous Films
AssigneePorous Power Technologies, LLC
InventorsKirby W. Beard, Ann M. Edwards
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Abstract
A microporous membrane may be manufactured using a polymer binder and a filler material using a liquid pore forming agent having a surface free energy that is lower than that of the filler and higher than that of the polymer. The repulsion of the pore forming agent to the polymer may form the pores of the membrane, while the attraction of the polymer to the filler may encapsulate the filler into the structure of the membrane. The filler may be particles that are on the order of or smaller than the wall thickness of the microporous structure.
Claims20
A method for producing a microporous membrane, said method comprising:
- mixing a polymer with a pore forming agent and a filler material to form a pre-formed mixture;
- solidifying said polymer in the presence of said pore forming agent and said filler material to form said microporous membrane where said filler material is incorporated into said microporous membrane and bound with said polymer;
- said microporous membrane comprising at least 2 parts of said filler material to 3 parts of said polymer by volume;
- said polymer having a surface free energy lower than said pore forming agent;
- and
- said polymer wetting said filler material.
The method of claim 5, said filler material having an average particle size less than 0.1 times said average wall thickness.
A method for producing a microporous membrane, said method comprising:
- mixing a polymer with a pore forming agent and a filler material to form a pre-formed mixture, said filler material being a spherical filler material;
- solidifying said polymer in the presence of said pore forming agent, a reinforcing web, and said filler material to form said microporous membrane where said filler material is incorporated into said microporous membrane and bound with said polymer;
- said microporous membrane comprising at least 2 parts of said filler material to 3 parts of said polymer by volume;
- and
- said pore forming agent having a surface free energy lower than said polymer.
Dependencies are inferred from the claim text.