US2010822A

US2010822A - Manufacture of cellulose acetate

Info

Publication number: US2010822A
Application number: US563230A
Authority: US
Inventors: Carl J Malm
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1931-09-16
Filing date: 1931-09-16
Publication date: 1935-08-13
Anticipated expiration: 1952-08-13

Description

2,010,822 MANUFACTURE OF CELLULOSE ACETATE Carl J. Malm, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New York T No Drawing. Application September 16, 1931,

Serial N0. 563,230 g 3 Claims. (Cl. 260-101) This application is a continuation-impart ofmy co-pending application Serial No. 336,922, filed February 1, 1929, now U. S. Patent No. 1,908,525. 1 v

The present invention relates to the pretreatment of cellulose with acetic acid and a chlorinated aliphatic hydrocarbon and then esterifying the pretreated cellulose. 1

One object of my invention is to utilize the bath in which cellulose hasbeen pretreated, to form the subsequent esterification bath'by merely adding esterifying ingredients to it after the pretreatment of the cellulose has been completed. The amount of chlorinated aliphatic hydrocarbon which is employed in the pretreatment bath together withthe organic acid is preferably the amount of the chlorinated hydrocarbon which is desired the esterification bath so that there will be no waste of this ingredient by using an excess in the pretreatment and so that it will be unnecessary to add more of this chlorinated hydrocarbon at any time after the pretreatment.

Of course, if additionalchlorinated hydrocarbon is preferred in certain cases, it may be added in compatible amounts providing it does not interfere with the esterification.

The present invention is an improvement of the process disclosed in U. S. Patent No. 1,823,359

of H. LeB. Gray, which discloses a process of acetylating cellulose in which the cellulose is pretreated with acetic acid and an acid catalyst, at the end of which treatment the mass of material is pressed until the ratio of acid to cellulose is approximately two to one. The cellulose is then acetylated with a mixture of acetic anhydride and ethylene chloride.

I have now found a process of acetylating cellulose wherein the intermediate step of pressing out the pretreatment liquid is unnecessary between the pretreatment, and the esterification of the cellulose. For example by my invention the pressing operation between the pretreatment and acetylation of the Gray application is unnecessary and can be eliminated so that a considerable saving in acetic acid which is necessary in any one operation may be effected.

I have found that the process described in the Gray application, referred to above, may be improved by pretreating the cellulose with a mixture of acetic acid and a chlorinated hydrocarbon, such as chloroform, ethylene dichlorid, methylene chloride, dichlorethylene, trichlorethylene,

or carbon tetrachlorid and then without pressing out any of the liquid absorbed from the pretreatment bath, acetylating thepretreated cellulose by adding the acetylating materials to the pretreatment batch. I have found that if the cellulose is pretreated with acetic acid together with a chlorinated hydrocarbon the acetic acid is evenly distributed throughout the cotton and a uniform and eflicient pretreatment obtained. An acetylation catalyst, such as sulfuric acid may be added to the pretreatment mixture or it may be added to the acetic anhydride in the esterification step as desired, or it may even be present as an impurity in some of the reagents employed.

As pointed out above, intermediate steps between the pretreatment and the esterification, such as for the removal of acetic acid are unnecessary in the performance of my invention.

The following example is an illustration of one embodiment of my invention:

About25 lbs. of cotton are treated with a mixture of about 25 lbs. of acetic acid and 175 lbs. of ethylene chloride for about 4 hours at about 100 F. The mixture is then cooled to approximately F. and then about lbs. of

acetic anhydride containing about lb. of sulfuric acid is added thereto. The temperature is then allowed to rise slowly to a maximum of about F. when a viscous clear solution is obtained denoting completion of the acetylation.

The reaction mixture or dope produced, which comprises cellulose acetate dissolved in acetic acid and ethylene chloride, is preferably treated in a precipitating bath at a temperature at or above the boiling point of ethylene chloride. For example, the mass may be poured into desires a fibrous acetylation process the amount of carbon tetrachloride need not be limited to non-precipitating proportions, but may be employed in substantial amounts; equal parts of carbon tetrachloride and glacial acetic acid in the pretreatment is preferred when using that particular chlorinated hydrocarbon.

Other modifications of my invention such as its use in the production of esters having higher acid radicals, such as cellulose propionate, cellulose acetate butyrate, etc.,or the use'of other known acetylation catalysts will be obvious to those skilled in the art and come within the contemplation of my invention.

I claim as my invention:

1. A process of acylating cellulose which comprises pretreating the cellulose with a bath comprising a fatty acid and ethylene chloride and subsequently adding a fatty acid anhydrid thereto. t

2. A process of acylating cellulose which comprises pretreating the cellulose with a bath comprising acetic acid. and. ethylene chloride and subsequently adding a fatty acid anhydrid thereto.

3. A process of acylating cellulose which comprises pretreating the cellulose with a bath comprising a fatty acid and ethylene chloride and subsequently adding a fatty acid anhydrid together with a catalyst thereto.

CARL J. MALM.