The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 09, 1999
Filed:
Jan. 22, 1997
Mitsuru Yamashita, Himeji, JP;
Daicel Chemical Industries, Ltd., Osaka, JP;
Abstract
In a production process of a cellulose acetate which comprises (a) a reduced pressure-acetylation step of acetylating a cellulose under a reduced pressure in the presence of sulfuric acid or other acidic catalyst, with distilling off a gaseous phase component of the reaction system out of the system, and (b) a post-acetylation step of allowing the acetylation to further proceed by increasing the pressure as compared with the pressure of the reduced pressure-acetylation step by means of release of the pressure reduction of the reaction system or the like, the shift operation from the reduced pressure-acetylation step to the post-acetylation step is conducted by taking a distilling rate of a distillate in the reduced pressure-acetylation step as an index to control the reaction temperature of the post-acetylation step. The shift operation from the reduced pressure-acetylation step to the post-acetylation step may also be conducted by taking a distilling rate after the distilling rate in the reduced pressure-acetylation step has reached a maximum value.