Method for forming a membrane into a predetermined shape
AssigneeThe Dow Chemical Company
InventorsGreg D. Solie, Matthew J. Hallan
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Abstract
A thin film membrane formed to a predetermined shape is produced by bending the membrane to create a loop and softening the membrane that makes up the loop with either thermal energy or a swelling solvent. The softened loop is then drawn between plates or about a mandrel to form a membrane with a predetermined fold radius. The fold region produced by the method of the instant invention does not require an adhesive sealant to prevent unfiltered liquid from diffusing through the membrane. The method is especially well suited for preparing membranes for use in the production of spiral wound filters.
Claims23
A method for folding a polymeric membrane comprising:
- (a) forming a polymeric membrane, having a supporting layer, an active layer, a front end and a back end, into a loop;
- (b) softening said loop by means of a softening source until said loop is adapted for drawing down to a fold;
- (c) drawing said loop to said fold;
- and
- (d) removing said fold from said softening source.
A method for folding a polymeric membrane at least twice comprising:
- (a) the sequence of steps of:
- (1) forming a polymeric membrane, having a supporting layer, an active layer, a front end and a back end, into a loop adjacent to constricting structures having a space therebetween such that the supporting layer contacts said constricting structures and the front end and back end extend through the space between the constricting structures;
- (2) softening said loop by means of a softening source until said loop is adapted for drawing down to a fold;
- (3) drawing said loop to said fold;
- (4) removing said fold from said softening source;
- and
- (b) the sequence of steps of:
- (1) forming a polymeric membrane, having a supporting layer, an active layer, a front end and a back end, into a loop around a mandrel such that the supporting layer contacts said mandrel;
- (2) softening said loop by means of a softening source until said loop is adapted for drawing down to a fold;
- (3) drawing said loop to said fold;
- (4) removing said fold from said softening source.
Dependencies are inferred from the claim text.