Microporous membranes of ultrahigh molecular weight polyethylene
First Claim
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1. A method for producing a microporous UHMW-PE membrane, including the steps ofa. forming a mixture comprising UHMW-PE and a porogen;
- b. heating the mixture to an elevated temperature to produce a solution of UHMW-PE and porogen;
c. extruding the solution of UHMW-PE and porogen through a forming die under moderate shear sufficient to enable employment of conventional extrusion equipment and/or techniques to thereby form a membrane;
d. cooling the membrane sufficiently to cause phase separation resulting in a polymer-rich, porogen-poor phase and a polymer-poor, porogen-rich phase in said membrane;
e. creating a microporous structure in the membrane by removing porogen from said membrane;
f. drying the microporous membrane.
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Abstract
Microporous membranes and methods for producing such membranes from ultrahigh molecular weight polyethylene are described. The method employs extrusion of a solution of UHMW-PE and porogen through a forming die followed by thermal phase separation of polymer and porogen. Microporous structures are created by removing porogen. Microporous membranes produced include membranes with good permeability to air and water making them particularly useful as filtration media and water-resistance breathable membranes.
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Citations
15 Claims
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1. A method for producing a microporous UHMW-PE membrane, including the steps of
a. forming a mixture comprising UHMW-PE and a porogen; -
b. heating the mixture to an elevated temperature to produce a solution of UHMW-PE and porogen; c. extruding the solution of UHMW-PE and porogen through a forming die under moderate shear sufficient to enable employment of conventional extrusion equipment and/or techniques to thereby form a membrane; d. cooling the membrane sufficiently to cause phase separation resulting in a polymer-rich, porogen-poor phase and a polymer-poor, porogen-rich phase in said membrane; e. creating a microporous structure in the membrane by removing porogen from said membrane; f. drying the microporous membrane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for producing a microporous ultra-high molecular weight polyolefin membrane, including the steps of:
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a. forming a mixture comprising ultra-high molecular weight polyolefin and a porogen; b. heating the mixture to an elevated temperature to produce a solution of ultra-high molecular weight polyolefin and porogen; c. extruding the solution of ultra-high molecular weight polyolefin and porogen through a forming die under moderate shear sufficient to enable employment of conventional extrusion equipment and/or techniques to thereby form a membrane; d. cooling the membrane sufficiently to cause phase separation resulting in a polymer-rich, porogen-poor phase and a polymer-poor porogen-rich phase in said membrane; e. creating a microporous structure in the membrane by removing porogen from said membrane; f. drying the microporous membrane.
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Specification