Patent ID: 6235893
Filing Date: 2001-05-22
Classification: A23L,C08B

Abstract:
A process for making cellulose ether, the cellulose ether having a methoxy substitution of about 21 to about 42 weight percent based upon the weight of the cellulose ether, the process comprising:a) a first stage comprisingi) contacting a cellulose pulp with a first amount of aqueous sodium hydroxide at reaction conditions sufficient to alkalize it to a first level of alkalization which is about 20 percent or more of a total level of alkalization; andii) contacting the cellulose pulp of first level of alkalization with a first amount of a methylating agent at reaction conditions sufficient to form cellulose ether having a first level of methoxy substitution which is about 20 percent or more of a total level of methoxy substitution; andb) a second stage comprisingiii) contacting the cellulose ether of first level of methoxy substitution with a second amount of aqueous sodium hydroxide at reaction conditions sufficient to alkalize it to a second level of alkalization which is about 40 percent or more of the total level of alkalization; andiv) continuously or incrementally contacting the cellulose ether of second level of alkalization with a second amount of a methylating agent over a period of time at reaction conditions sufficient to form a cellulose ether of a second level of methoxy substitution which is about 40 percent or more of the total level of methoxy substitution, the second amount of the methylating agent providing about 20 percent or more of the total level of methoxy substitution, the second amount of methylating agent being contacted with the cellulose ether of second level of alkalization at about 65.degree. C. to about 120.degree. C. for 15 minutes or more; andc) washing the cellulose ether of total level of methoxy substitution; andd) drying the cellulose ether of total level of methoxy substitution to a reduced moisture and volatiles content; ande) milling the cellulose ether of total level of methoxy substitution to a particulate form.