Gas-permeable membrane
OwnerRaymond Clarke, Charles B. Derringerinventors
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Abstract
Gas-permeable membranes comprising a microporous film and a coating on the microporous film, the coating being obtained by coating the microporous film with a liquid coating composition comprising a polymer and hollow polymeric particles dispersed in the composition, and then solidifying the coating. The gas-permeable membrane has a reduced ratio of carbon dioxide permeability to oxygen permeability.
Claims20
A gas-permeable membrane which comprises
- (1) a microporous film, and
- (2) a solid coating on the microporous film, the coating comprising
- (a) a matrix comprising a first polymer, and
- (b) hollow particles which (i) are composed of a polymeric composition comprising a second polymer which is different from the first polymer, (ii) are dispersed in the matrix, and (iii) have a maximum dimension which is at most 50% of the thickness of the solid coating.
A gas-permeable membrane which comprises
- (1) a microporous film, and
- (2) a solid coating on the microporous film, the coating comprising
- (a) a matrix comprising a first polymer which is at least one side chain crystalline polymer having a peak melting temperature Tp of −5 to 40° C., and a heat of fusion of at least 10 J/g, and
- (b) hollow particles which (i) are composed of a polymeric composition comprising a second polymer which is different from the first polymer, (ii) are dispersed in the matrix, and (iii) have a maximum dimension which is at most 50% of the thickness of the solid coating.
A method of preparing a gas-permeable membrane which comprises a microporous film and a solid polymeric coating on the microporous film, the method comprising
- (A) forming a liquid coating on the microporous film, the liquid coating being composed of liquid coating composition which comprises
- (a) a first polymer, and
- (b) hollow particles which (i) are dispersed in the coating composition, and (ii) are composed of a polymeric composition comprising a second polymer, the second polymer being different from the first polymer;
- and
- (B) solidifying the liquid coating on the microporous film;
- the hollow polymeric particles having a maximum dimension which is at most 50% of the thickness of the solid coating.
A method according to claim 19 wherein step (B) comprises heating which at least partially melts at least some of the hollow polymeric particles so that they fuse together to form a plurality of microscopic voids.
Dependencies are inferred from the claim text.