Regioselectively substituted cellulose esters produced in a carboxylated ionic liquid process and products produced therefrom

Abstract

This invention relates to novel compositions comprising regioselectively substituted cellulose esters. One aspect of the invention relates to processes for preparing regioselectively substituted cellulose esters from cellulose dissolved in ionic liquids. Another aspect of the invention relates to the utility of regioselectively substituted cellulose esters in applications such as protective and compensation films for liquid crystalline displays.

1 . A process of making a regioselectively substituted cellulose ester said process comprising:
 (a) dissolving cellulose in a carboxylated ionic liquid to thereby form a cellulose solution;   (b) contacting said cellulose solution with at least two acylating reagents to thereby provide an acylated cellulose solution comprising a cellulose ester, wherein said cellulose ester comprises at least one acyl group donated by said carboxylated ionic liquid; wherein said acylating reagents are contacted consecutively in stages with said cellulose solution;   (c) contacting said acylated cellulose solution with a non-solvent to cause at least a portion of said cellulose ester to precipitate and thereby provide a slurry comprising precipitated cellulose ester and said carboxylated ionic liquid;   (d) separating at least a portion of said precipitated cellulose ester from said carboxylated ionic liquid to thereby provide said regioselectively substituted cellulose ester and a separated carboxylated ionic liquid; and   (e) optionally, recycling at least a portion of said separated carboxylated ionic liquid for use in dissolving additional cellulose.   
     
     
         2 . A process according to  claim 1  wherein about 80 mole percent of a first acylating reagent is allowed to react prior to adding the next acylating agent. 
     
     
         3 . A process of making a regioselectively substituted cellulose ester said process comprising:
 (a) dissolving cellulose in a carboxylated ionic liquid to thereby form a cellulose solution;   (b) contacting said cellulose solution with at least two acylating reagents to thereby provide an acylated cellulose solution comprising a cellulose ester, wherein said cellulose ester comprises at least one acyl group donated by said carboxylated ionic liquid; wherein said acylating reagents are added simultaneously to said cellulose solution;   (c) contacting said acylated cellulose solution with a non-solvent to cause at least a portion of said cellulose ester to precipitate and thereby provide a slurry comprising precipitated cellulose ester and said carboxylated ionic liquid;   (d) separating at least a portion of said precipitated cellulose ester from said carboxylated ionic liquid to thereby provide said regioselectively substituted cellulose ester and a separated carboxylated ionic liquid; and   (e) optionally, recycling at least a portion of said separated carboxylated ionic liquid for use in dissolving additional cellulose.