Method of adjusting the degree of substitution with acetyl group of cellulose acetate

Abstract

A process for adjusting an intermolecular or intramolecular degree of acetyl substitution of cellulose acetate is disclosed. The process comprises ripening cellulose acetate in the presence of a catalyst, an acetyl donor, and water or an alcohol. The amount of water and the alcohol is in the range of 0.1 to 10 mol % based on the amount of the acetyl donor.

1 . Cellulose acetate having a degree of acetyl substitution in the range of 2.636 to 2.958, wherein the cellulose acetate shows a distribution curve of an intermolecular substitution degree in which the maximum peak has a half width of less than 0.080, and wherein the degrees of acetyl substitution at 2-, 3- and 6-positions satisfy the following formula (I):
   2 DS+ 3 DS< 6 DS× 4−1.70  (I)   in which 2DS is the degree of acetyl substitution at 2-position; 3DS is the degree of acetyl substitution at 3-position; and 6 DS is the degree of acetyl substitution at 6-position.   
   
   
       2 . The cellulose acetate as defined in  claim 1 , wherein the maximum peak has a half width of less than Y defined in the following formula:
     Y=− 0.17788 X+ 0.5788   in which X is the degree of acetyl substitution.   
   
   
       3 . Cellulose acetate having a degree of acetyl substitution in the range of 2.636 to 2.958, wherein the cellulose acetate shows a distribution curve of an intermolecular substitution degree in which the maximum peak has a half width of less than Y defined in the following formula:
     Y=− 0.17788 X+ 0.5788   in which X is the degree of acetyl substitution, and wherein the degrees of acetyl substitution at 2-, 3- and 6-positions satisfy the following formula (I):
   2 DS+ 3 DS< 6 DS× 4−1.70  (I) 
   in which 2DS is the degree of acetyl substitution at 2-position; 3DS is the degree of acetyl substitution at 3-position; and 6DS is the degree of acetyl substitution at 6-position.   
   
   
       4 . Cellulose acetate showing an infrared absorption spectrum, wherein the absorption spectrum has the absorption maximum in the wave number range of 3450 to 3550 cm −1  in which the absorption maximum has a half width of 135 cm −1  or less, wherein the degrees of acetyl substitution at 2-, 3- and 6-positions satisfy the following formula (I):
   2 DS+ 3 DS< 6 DS× 4−1.70  (I)   in which 2DS is the degree of acetyl substitution at 2-position; 3DS is the degree of acetyl substitution at 3-position; and 6DS is the degree of acetyl substitution at 6-position.   
   
   
       5 . Cellulose acetate in which the degrees of acetyl substitution at 2-, 3- and 6-positions satisfy the following formulas (I) to (III):
   2 DS+ 3 DS< 6 DS× 4−1.70  (I)     2 DS+ 3 DS<− 6 DS× 4+5.70  (II)     2 DS+ 3 DS> 1.80  (III)   in which 2DS is the degree of acetyl substitution at 2-position; 3DS is the degree of acetyl substitution at 3-position; and 6DS is the degree of acetyl substitution at 6-position.   
   
   
       6 . The cellulose acetate defined in  claim 5 , wherein the degrees of acetyl substitution at 2-, 3- and 6-positions further satisfy the following formula (VI):
   2 DS+ 3 DS− 6 DS< 1  (VI)   in which 2DS is the degree of acetyl substitution at 2-position; 3DS is the degree of acetyl substitution at 3-position; and 6DS is the degree of acetyl substitution at 6-position.   
   
   
       7 . The cellulose acetate defined in  claim 5 , wherein the degrees of acetyl substitution at 2- and 3-positions further satisfy the following formula (VII):
   2 DS+ 3 DS> 1.82  (VII)   in which 2DS is the degree of acetyl substitution at 2-position; and 3DS is the degree of acetyl substitution at 3-position.   
   
   
       8 . The cellulose acetate defined in  claim 7 , wherein the degrees of acetyl substitution at 2- and 3-positions further satisfy the following formula (VIII):
   2 DS+ 3 DS> 1.84  (VIII)   in which 2DS is the degree of acetyl substitution at 2-position; and 3DS is the degree of acetyl substitution at 3-position.   
   
   
       9 . Cellulose acetate in which the degrees of acetyl substitution at 2-, 3- and 6-positions satisfy the following formulas (I), (III) and (IV):
   2 DS+ 3 DS< 6 DS× 4−1.70  (I)     2 DS+ 3 DS> 1.80  (III)     3DS<2DS  (IV)   in which 2DS is the degree of acetyl substitution at 2-position, 3DS is the degree of acetyl substitution at 3-position, and 6DS is the degree of acetyl substitution at 6-position.   
   
   
       10 . The cellulose acetate defined in  claim 9 , wherein the degree of acetyl substitution at 6-position further satisfies the following formula (IX):
   6DS<0.98  (IX)   in which 6DS is the degree of acetyl substitution at 6-position.   
   
   
       11 . The cellulose acetate defined in  claim 9 , wherein the degrees of acetyl substitution at 2- and 3-positions further satisfy the following formula (VII):
   2 DS+ 3 DS> 1.82  (VII)   in which 2DS is the degree of acetyl substitution at 2-position; and 3DS is the degree of acetyl substitution at 3-position.   
   
   
       12 . The cellulose acetate defined in  claim 11 , wherein the degrees of acetyl substitution at 2- and 3-positions further satisfy the following formula (VIII):
   2 DS+ 3 DS> 1.84  (VIII)   in which 2DS is the degree of acetyl substitution at 2-position; and 3DS is the degree of acetyl substitution at 3-position.   
   
   
       13 . The cellulose acetate defined in  claim 9 , wherein the cellulose acetate has a degree of acetyl substitution in the range of 2.636 to 2.958, and wherein the cellulose acetate shows a distribution curve of an intermolecular substitution degree in which the maximum peak has a half width of less than 0.080. 
   
   
       14 . The cellulose acetate defined in  claim 9 , wherein the cellulose acetate has a degree of acetyl substitution in the range of 2.636 to 2.958, and wherein the cellulose acetate shows a distribution curve of an intermolecular substitution degree in which the maximum peak has a half width of less than Y defined in the following formula:
     Y=− 0.17788 X+ 0.5788   in which X is the degree of acetyl substitution.   
   
   
       15 . The cellulose acetate defined in  claim 9 , wherein the cellulose acetate shows an infrared absorption spectrum, and wherein the absorption spectrum has the absorption maximum in the wave number range of to 355 cm −1  in which the absorption maximum has a half width of 135 cm −1  or less.