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| Heating pad |
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| Osmotic device for dispensing two different medications |
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|
Spray-applied fluoropolymer films for gas separation membranes
| Details |
Inventors: Blanchet-Fincher, Graciela B.;
Assignee: E. I. Du Pont de Nemours and Company (Wilmington, DE)
Primary Examiner: Spitzer; Robert
Assistant Examiner:
Attorney, Agent or Firm:
Disclosed is a process for preparing gas separation membranes wherein a thin film of an amorphous fluoropolymer is spray-deposited as an aerosol onto a microporous substrate and rendered substantially continuous or defect-free by thermal and/or chemical treatment. |
|
DETAILED DESCRIPTION What is claimed is: 1.
A Process for preparing a gas separation membrane comprising a microporous solid substrate having on one surface a thin, substantially continuous film of an amorphous polymer of bis-2,2-trifluoromethyl-4,5-difluoro-1,3-dioxole, said process comprising the steps of: (a) preparing a solution of said polymer in an organic liquid solvent; (b) atomizing the solution from step (a) in an inert gas to form an aerosol spray of droplets, said droplets having a size in the range of about 1 to about 100 micrometers; (c) directing said aerosol spray on to, and coating said porous substrate to a film thickness of less than about 100 micrometers, the porous substrate being heated to a temperature in the range of about 125.
degree.
to about 280.
degree.
C.
; and (d) annealing the polymer film formed in step (c) at a temperature of at least about 280.
degree.
C.
for over 1 hour.
2.
Process according to claim 1 wherein the polymer solution comprises about 0.
1% to about 4% by weight of polymer and about 96% to about 99.
9% by weight of the organic liquid solvent.
3.
Process according to claim 1 wherein the organic liquid solvent is fluorinated.
4.
Process according to claim 3 wherein the solvent is selected from the group consisting of C.
sub.
6 F.
sub.
14, C.
sub.
7 F.
sub.
16 or C.
sub.
8 F.
sub.
18 isomer mixtures, fluorinated mixtures containing (C.
sub.
4 F.
sub.
9).
sub.
2 NCF.
sub.
3, perfluorotetradecahydrophenanthrene oligomer mixtures, perfluoro-n-methylmorpholine, perfluorinated mixtures of C.
sub.
8 F.
sub.
16 O cyclic ethers containing perfluoro-2-n-butyltetrahydrofuran, perfluorotributylamine and perfluorotriamylamine.
5.
Process according to claim 4 wherein the solvent is a fluorinated mixture containing (C.
sub.
4 F.
sub.
9).
sub.
2 NCF.
sub.
3.
6.
Process according to claim 1 wherein the amorphous bis-2,2-trifluoromethyl-4,5-difluoro-1,3-dioxole polymer is a homopolymer.
7.
Process according to claim 1 wherein the amorphous polymer is a copolymer of bis-2,2-trifluoromethyl-4,5-difluoro-1,3-dioxole with a comonomer selected from the group consisting of tetrafluoroethylene, perfluoromethyl vinyl ether, vinylidene fluoride and chlorotrifluoroethylene
|
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