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AssigneeE.I. du Pont de Nemours and Company
InventorsJennifer Marie Galvin, Henricus Jacobus Cornelis Gommeren, Rachel Elizabeth Montejo, Tina Amick Waller
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An improved casting substrate is provided for use in a composite membrane for use as a fluid filtration medium. The composite membrane has good adhesion between the casting substrate and the microporous membrane while maintaining high permeability. The casting substrate comprises a single spunbond layer or a multiple spunbond layers formed of thermoplastic fibers, optionally comprising at least one meltblown layer. The casting substrate allows the membrane casting solution to penetrate the casting substrate uniformly to a controlled depth without penetrating through the entire thickness of the substrate. The casting substrate has good uniformity of mean pore size, basis weight, thickness and surface roughness.
A casting substrate in combination with a casting of a microporous membrane thereon and supporting the microporous membrane in a composite membrane, the casting substrate having a casting surface comprising a porous spun bond layer having a casting surface substantially free of raised fibers and loops and a bottom surface and having a pore size gradient through the thickness thereof, wherein the casting surface has a mean pore size of between about 15 μm and about 200 μm and the bottom surface has a mean pore size of between about 1 μm and about 20 μm and the microporous membrane is cast onto the casting surface that has a mean pore size of between about 15 μm and about 200 μm.
A casting substrate in combination with a casting of a microporous membrane thereon and supporting the microporous membrane in a composite membrane, the casting substrate having a casting surface substantially free of raised fibers and loops comprising a first porous spunbond layer having a casting surface laminated to a second porous spunbond layer, wherein the mean pore size of the first porous spunbond layer is between about 10 μm and about 200 μm and the mean pore size of the second porous spunbond layer is between about 1 μm and about 20 μm and the microporous membrane is cast onto the casting surface of the first spunbond layer that has a mean pore size of between about 10 μm and about 200 μm.
A process for forming a composite membrane comprising a microporous membrane layer and a casting substrate, comprising the steps:
Dependencies are inferred from the claim text.