Ultrathin cellulose ester polymer films and their preparation

Claim 2

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.

Claim 3

The film of claim 1 wherein the cellulose ester is cellulose acetate, cellulose triacetate, cellulose butyrate, cellulose propionate, cellulose acetate butyrate or cellulose acetate propionate.

Claim 4

The film of claim 1 wherein the cellulose ester is cellulose triacetate.

Claim 5

The film of claim 1, 2, or 3 wherein the thickness is in the range of about 70 to about 160 angstroms.

Claim 6

The film of claims 1, 2 or 3 wherein the film is prepared from a casting solution containing a cellulose ester polymer at about the 80 to about the 100 percent by weight level and another polymer or polymers at about the 20 to about the 0 percent by weight level based upon the total weight of the polymers dissolved in the solution.

Claim 7

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.

Claim 8

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.

Claim 9

The film of claim 6 wherein the cellulose ester is cellulose acetate, cellulose triacetate, cellulose butyrate, cellulose propionate, cellulose acetate butyrate or cellulose acetate propionate.

Claim 10

The film of claim 6 wherein the cellulose ester is cellulose triacetate.

Claim 11

The film of claim 6, or 7 wherein the cellulose polymer is present at about the three to about the seven percent by weight level in the casting solution based upon the total weight of the casting solution.

Claim 12

The film of claim 9 wherein the polymer is present at about the four to about five percent by weight level.

Claim 13

The film of claim 6, or 7 wherein the casting solution contains about 91:50:9 by volume ratio of 1,2,3-trichloropropane:methylene chloride:methanol.

Claim 14

The film of claim 9 wherein the casting solution contains about a 91:50:9 by weight ratio of 1,2,3-trichloropropane:methylene chloride:methanol.

Claim 15

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.

Claim 16

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.

Claim 17

The film of claim 13 wherein the cellulose triacetate polymer is present at about the three to about the seven percent by weight level.

Claim 18

The film of claim 13 wherein the cellulose triacetate polymer is present at about the four to about the five percent by weight level.

Claim 19

The film of claim 13 wherein the casting solution contains about a 91:50:9 by volume ratio of 1,2,3-trichloropropane:methylene chloride:methanol.

Claim 20

The film of claim 6, 7 or 13 wherein the casting solution contains a cellulose ester polymer at about the 30 to about the 100 percent by weight level and another polymer or polymers at about the 20 to about the 0 percent by weight level based upon the total weight of the polymers dissolved in the casting solution.