Regioselectively substituted cellulose esters produced in a halogenated 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) introducing a reaction medium comprising cellulose, a halide ionic liquid and a binary component into an esterification zone; and   (b) combining at least one acylating reagent with said reaction medium in said esterification zone to esterify at least a portion of said cellulose thereby producing said regioselectively substituted cellulose ester; wherein said acylating reagent is added at one time or in consecutive stages.   
     
     
         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 a cellulose in a halide ionic liquid to thereby form an initial cellulose solution;   (b) contacting said initial cellulose solution with a binary component and an acylating reagent under conditions sufficient to provide an acylated cellulose solution comprising a cellulose ester; wherein said acylating reagent is added at one time or in consecutive stages;   (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 at least a portion of said halide ionic liquid;   (d) separating at least a portion of said precipitated cellulose ester from said halide ionic liquid to thereby provide a recovered cellulose ester and a separated halide ionic liquid; and   (e) optionally, recycling at least a portion of said separated halide ionic liquid for use in dissolving additional cellulose.