US 5,928,613 A · Apparatus for acetylating cellulose

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.

Claims6

Dependent claims

An apparatus for controlling a reaction in a production process of a cellulose acetate, which comprises:

(a) an acetylation reactor for acetylating a cellulose under a first pressure in the presence of an acidic catalyst;
(b) pressure reducing means for reducing the pressure of the reaction system;
(c) condensing means for condensing under a given pressure, a gaseous phase component produced during said acetylation to produce a distillate;
(d) monitoring means for monitoring a distilling rate under said first pressure in said distilling step;
(e) pressure regulating means for raising the pressure inside the acetylation reactor to a second pressure when the distillation rate under said given pressure reaches a predetermined reference value of the distillation rate or lower,
whereby upon increasing the pressure to said second pressure said acetylation reaction continues under said second pressure, wherein said first pressure is lower than atmospheric pressure, said first pressure is lower than said second pressure, and said reference value of the distilling rate is 2 to 15 parts by weight per minute relative to 100 parts by weight cellulose.

3 more elements

Dependencies are inferred from the claim text.

Apparatus for acetylating cellulose

Life of this patent

Apparatus for acetylating cellulose

Life of this patent

Abstract

Claims6