US2126851A

US2126851A - Organic derivatives of cellulose

Info

Publication number: US2126851A
Application number: US103396A
Authority: US
Inventors: Whitehead William
Original assignee: Celanese Corp
Current assignee: Celanese Corp
Priority date: 1936-09-30
Filing date: 1936-09-30
Publication date: 1938-08-16
Anticipated expiration: 1955-08-16

Description

Patented Aug. 16, 1938 UNITED STATES ORGANIC DERIVATIVES OF CELLULOSE William Whitehead, Cumberland, Md, assignor to Celanese Corporation of America, a corporation of Delaware No Drawing. Application September 30, 1936, Serial No. 103,396

3 Claims.

This invention relates to the treatment of organic derivatives of cellulose, such. as the organic esters of cellulose, to remove therefrom, or to make inactive, corrosive compounds or compounds that cause the organic derivatives of cellulose to have a corrosive effect on metallic surfaces. The so treated organic derivatives of cellulose may be formed into filaments, films and molded articles without appreciably corroding the spinning jets or other metallic surfaces contacted by solutions of the organic derivative of cellulose.

An object of the invention is the economic and expeditious production of organic derivatives of cellulose that, when dissolved in a solvent, form solutions that are less corrosive than similar solutions formed of untreated organic derivatives of cellulose. Other objects of the invention will appear from the following detailed description.

In the production of organic derivatives of cellulose there are produced various compounds that are either corrosive to metals or, when an organic derivative of cellulose is dissolved in a solvent therefor, cause the formation of compounds that are .corrosive to metals. Examples of one type of such compounds are those containing sulphur. These compounds, prior to this invention, were separated from the derivatives of cellulose, if at all, only by elaborate and involved treatments. By employing this invention, however, organic esters of cellulose either before, during, or after being stabilized, are treated with an agent that tends to remove corrosive compounds, or compounds which tend to produce corrosive compounds. The treatment with the agent is simple and inexpensive. The treatment, in accordance with this invention is carried out to such an extent as to produce an organic derivative of cellulose that is substantially non-corrosive and is completed in a short period of time. This treatment not only reduces to a negligible amount the corrosiveness of the organic derivative of cellulose, but also removes or destroys those compounds which form insoluble filter blocking and jet blocking materials in spinning solutions. 1

Organic derivatives of cellulose treated in accordance with this invention may be spun into filaments by extruding the same through jets into a solidifying medium. The organic deriva-.

tive of cellulose so treated does not materially attack the metal surrounding the orifice. When the metal of the spinning jet is attacked, the size of the orifice is enlarged or particles of the corroded metal wedged in the orifice, thus producing filaments of undesired denier. Furthermore, since organic derivatives of cellulose treated in accordance with this invention do not attack metal parts contacted thereby, they do not pick up metallic salts which tend to discolor articles formed therefrom.

In accordance with this invention, I treat precipitated or solid organic derivatives of cellulose, preferably at elevated temperatures, with a dilute solution of an organic compound having a basic reaction, for example, hydroxy amines, diamines, straight chain aliphatic amines and cyclic amines. After this treatment the derivatives of cellulose may be Washed substantially free of the treating compound and/or the reaction products formed by same or, if desired, at least a trace of the treating compound may be left in the derivative of cellulose. The organic derivative of cellulose may be treated before or after the treatment with the organic compounds having a basic reaction with chlorine or a chlorine-liberating compound such as sodium hypochlorite. The organic derivative of cellulose thus treated, when dissolved in a solvent therefor, forms a solution which is substantially noncorrosive.

This invention is especially applicable to the treatment of any corrosive organic esters of cel lulose such as cellulose acetate, cellulose formate, cellulose propionate and cellulose butyrate made by processes which tend to produce corrosive materials. It is also applicable, in a general way, to the treatment of nitrocellulose, cellulose ethers and mixed esters and ethers of cellulose. Examples of cellulose ethers are ethyl cellulose, methyl cellulose and benzyl cellulose.

The organic esters of cellulose that lend themselves to this invention may be made by any of the methods now employed to make the same. For example, cellulose (cotton linters, cotton, Wood pulp, etc.) with or without a pretreatment in organic acid such as acetic acid and formic acid, is esterified by. treating the same with an acid anhydride in the presence of an acid solvent and a catalyst. In place of the acid solvent or in connection therewith there may be used suspension liquids such as benzol. The acid solvent may be a concentrated acid corresponding to the anhydride employed or it may be, as is preferred, glacial acetic acid. Examples of catalysts are sulphuric acid, phosphorous acid, hydrochloric acid, Zinc chloride and mixtures of these.

After esterification, suflicient water may be added to convert any remaining anhydride to the corresponding acid and the mixture hydrolized or ripened until the desired solubility characteristics are developed. The catalyst is then neutralized and water or other non-solvent for the ester added to precipitate the ester. During this precipitation step, the ester may, if desired, be treated with a solution of a hypochlorite or other chlorine-liberating compound to bleach the same. The ester is then separated and washed free of the acid solution. The cellulose ester may then be stabilized by treating with boiling water containing small amounts of mineral acid or with steam with or without pressure. Although stabilized, the ester may contain compounds which, when the ester is in solution, cause the solution to corrode or attack metals.

I have found that if the ester is treated after precipitation, but prior to stabilizing, by soaking able compounds may be removed or diminished.

to below an effective quantity by soaking the stabilized ester in a dilute solution of an organic compound having a basic reaction. The latter method of treating stabilized esters is preferable as it is in general more effective and has less tendency to alter viscosity and solubility characteristics of the ester. The soaking treatment is preferably carried on at elevated temperature, for instance, at from 50 to 100 C. Although the soaking of the precipitated derivative of cellulose in the dilute solution is the preferred method, other methods may be employed such as spraying the solution on the derivative of cellulose, or working the derivative of cellulose in a countercurrent manner in a stream of the dilute solution of the organic compound having a basic reaction.

The treating liquid or bath may be formed by dissolving any suitable organic compound having a basic reaction or suspending the same in an aqueous medium. As stated above, the organic compounds having a basic reaction may be hydroxy amines such as mono-, dior triethanolamine, di-amines such as ethylene diamines, straight chain aliphatic amines such as amylamines and cyclic amines such as pyridine, piccolines and lutidines. When treating organic esters of cellulose, the percentage of the organic compound in the treating bathshould be small enough so that substantially no saponification or change in-viscosityof the ester occurs. The amount of the aqueous solution or suspension of the organic basic compounds is preferably from 4 to 20Tor. more times the weight of the derivative of cellulose, the;concentration being such that the amount of organic basic com pound used is between 0.03 to 1% on the weight of'the derivative of cellulose employed, andis preferably from 0.1 to 0.5%. Although the treating bath may be of any suitable temperature, for instance from 50 to 100 C., it has been found preferable to maintain the temperature at from C. to the boiling point of the bath. Although an elevated'temperature is preferred, effective results may be obtained at room temperature especially when employing compounds most basic in reaction.

The treatment of the derivative of cellulose with the organic basic compound may be precipitated or followed by a treatment with an alkaline hypochlorite. The alkaline hypochlorite treatment is not absolutely necessary. The treatment with the organic basic compound is sufiicient to form non-corrosive derivatives of cellulose where it is undesirable to use thereon chlorine bleaching agents.

To further describe the invention and not as a limitation, the following examples are given:

Example I Stabilized cellulose acetate, washed neutral, is

'suitable solvent.

boiled with 364% by weight of the cellulose acetate of ethylene di-amine for two hours and then again washed neutral, dried and dissolved in a suitable solvent. The cellulose acetate is found to be greatly improved in its non-corrosive properties. For instance, the cellulose acetate is found to be substantially non-corrosive to copper and but very slightly corrosive to mercury and steel, whereas the original cellulose acetate was corrosive to all three metals.

Example II Stabilized cellulose acetate, washed neutral, is boiled'with .8% tri-ethanolamine, by weight of the cellulose acetate, for two hours-and .then again washed neutral, dried and dissolved in a The cellulose acetate is found to be greatly improved in its non-corrosive properties.

Example III Stabilizedv cellulose acetate, washed neutral, is boiledwith 0.6%,by weight .of the cellulose acetate of amylamine for twohours and then again washedneutral, dried and dissolved in a suitable solvent. The. cellulose acetateis found to be greatly improvedin its non-corrosive properties. During thetreatment a. strong odor of hydrogensulphide is given off.

Example IV Stabilized cellulose acetate, washed neutral, is boiled with .04% .by. weight of the cellulose acetate of pyridine .for two hours and then again washed. neutral, driedand dissolved in a suitablesolvent. The celluloseacetate is found to be greatly improved inits non-corrosive properties. During the treatment a strong odor of hydrogen sulphide is given off.

Itis. to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without :departingfrom the spirit of my invention.

Havingdescribed my invention, what I desire to.secure by Letters Patent is:

1. Method of reducingthe corrosive properties of. cellulose acetate, which comprises treatinga stabilized cellulose acetate with an aqueous .so-

lution containingfrom 0.3 to 1.0%, based onthe weight. of. the cellulose acetate present, of an organic base selected from the groupconsisting of'hydroxy amines, di-amines, straight chain ali-v phatic. amines, and cyclic amines.

2. Method of reducing the. corrosive properties of cellulose acetate, which comprises treating at a temperature of'from 50 to C. a stabilized cellulose acetate with an aqueous solution con-- taining from 0.3 to 1.0%, based on they weight of the. cellulose acetate present, .of an'organic base. selectedfrom thev group consisting of hy droxy amines, di-amines, straight chain aliphatic taining, from 0.3-to 1.0%, based'on the weight" of the cellulose acetate present, of an organic base=selected-from the group'consisting-of hydroxy amines,-di-amines, s'traight'chain aliphatic amines and" cyclic amines.

WILLIAM WHITEHEAD.