Ultrathin cellulose ester polymer films and their preparation
AssigneeHoechst Celanese Corporation
InventorRachel S. Kohn
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Abstract
Disclosed herein are pinhole-free, ultrathin, free-standing cellulose ester films having thicknesses of 400 angstroms or less and a process to prepare them. The films find particular utility in separatory applications.
Claims17
An ultrathin cellulose ester free-standing film containing no holes more than about one micron in diameter and having a thickness of about 160 angstroms or less and randomly oriented molecules.
An ultrathin, cellulose ester film containing no holes more than about one micron in diameter and having a thickness of about 400 angstroms or less and randomly oriented molecules prepared according to the process comprising:
- (a) preparing a casting solution containing a cellulose ester polymer at about the two to about the twelve percent by weight level, based on the total weight of the casting solution, in about a 85:52:13 to about a 100:45:5 by volume ratio of 1,2,3-trichloropropane:methylene chloride:methanol;
- (b) depositing the casting solution on water to form a free-standing film;
- and
- (c) removing the film from the water.
An ultrathin, cellulose triacetate film containing no holes more than about one micron in diameter and having a thickness of about 400 angstroms or less and randomly oriented molecules prepared according to the process comprising:
- (a) preparing a casting solution containing a cellulose triacetate polymer present at about the two to about the twelve percent by weight level, based upon the total weight of the casting solution, in about a 85:52:13 to about a 100:45:5 by volume ratio of 1,2,3-trichloropropane:methylene chloride:methanol;
- (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.