US 10,870,086 B2 · Polymeric membranes

Abstract

Disclosed is a method and apparatus for manufacturing a continuous web of polymeric membrane and for continuous downstream processing of said web. The apparatus (10) comprises: a casting station (20) for casting the continuous web (M); a carrier (24) for carrying the web downstream; a membrane drier (30) downstream of the carrier, for drying the web; and a brushing station (40) downstream of the drier for brushing the web. Said drier is located immediately downstream of the carrier, and upstream of said brushing station. The apparatus (10) further includes an additional drying station (50) downstream of the brushing station (40). Brushing after drying retains more surfactant in the membrane which is useful for certain applications. In addition, initial drying eliminates virtually all solvents from the membrane, but leaves some non-solvent (e.g. water) within it, which in turn fixes the surfactant on the nitrocellulose fibers, which improves significantly the consistency and reproducibility of the membrane.

Claims8

Dependent claims

A method for manufacturing a nitrocellulose membrane comprising the steps of:

a) providing a membrane casting mixture containing at least a nitrocellulose polymer, a polymer solvent, and a surfactant;
b) casting said mixture on a carrier;
c) initially drying said mixture to allow at least about 98% by weight of the polymer solvent content of the mixture to evaporate during said initial drying thereby fixing said surfactant in the membrane to thereby form a dried porous nitrocellulose polymeric membrane;
d) removing particles of dust on the surface of said dried membrane;
and
e) following step d) further drying the membrane, wherein the dried membrane has a surfactant content of at least 0.5% by weight.

3 more elements

Dependencies are inferred from the claim text.

Polymeric membranes

Life of this patent

Polymeric membranes

Life of this patent

Abstract

Claims8