Ultrathin blended cellulose nitrate polymer films and their preparation
AssigneeHoechst Celanese Corporation
InventorRachel S. Kohn
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Abstract
Disclosed herein are free-standing, pinhole-free, ultrathin, blended, cellulose nitrate films having thicknesses of about 400 angstroms or less and a process to prepare them. The films find particular utility in separatory applications.
Claims15
A process for preparing a blended, cellulose nitrate polymer film having a thickness of about 400 angstroms or less and containing no macroscopic holes, wherein the process comprises:
- (a) preparing a casting solution containing a cellulose nitrate polymer at about the two to about the eight percent by weight level and a methacrylate polymer at about the one to about the five percent by weight level, based upon the total weight of the casting solution, in about a 4:6 to about a 6:4 by volume ratio of a C.sub.1 -C.sub.4 lower alkyl and a C.sub.5 -C.sub.10 higher alkyl acetate, respectively;
- (b) depositing the casting solution on water to form a free-standing film;
- and
- (c) removing the film from the water.
A process for preparing a blended cellulose nitrate polymer film having a thickness of about 400 angstroms or less and containing no macroscopic holes, wherein the process comprises:
- (a) preparing a casting solution containing a cellulose nitrate polymer at about the two to about the eight percent by weight level and a C.sub.1 -C.sub.8 alkyl methacrylate polymer at about the one to about the five percent by weight level based upon the total weight of the casting solution in about a 4:6 to about a 6:4 by volume ratio of ethyl acetate:pentyl acetate;
- (b) depositing the casting solution on water to form a free-standing film;
- and
- (c) removing the film from the water.
A process for preparing a blended, cellulose nitrate polymer film having a thicknesses of about 400 angstroms or less and containing no macroscopic holes, wherein the process comprises:
- (a) preparing a casting solution containing a cellulose nitrate polymer at about the four to about the seven percent by weight level and a methylmethacrylate polymer or copolymer, a poly n-butylmethacrylate polymer or a poly isobutylmethacrylate polymer at about the two to about the four percent by weight level, based upon the total weight of the casting solution, in a about a 1:1 by volume ratio of ethyl acetate:pentyl acetate;
- (b) depositing the casting solution on water to form a free-standing film;
- and
- (c) removing the film from the water.
Dependencies are inferred from the claim text.