US2010607A - Process for the manufacture of cellulose esters - Google Patents

Description

Patented Aug. 6, 1935 PROCESS FOR THE MANUFACTURE OF CELLULOSE ESTERS Andreas Ruperti, Basel, Switzerland, assignor to the firm of Society of Chemical Industry in Basle, Basel, Switzerland No Drawing. Application May 26, 1930, Serial No. 455,967. In Switzerland June 1, 1929 Claims. (Cl. 8-20) The present invention relates to the manufacpronounced when the operation is conducted in ture of cellulose esters and to the products 015- complete absence of conditions which degrade tained according to the new process. cellulose and in particular when no injurious According to this invention cellulose esters are catalyst has been used. Similarly very valuable made by the action of an organic acid anhydride are the bodies which may be obtained by im- 5 on the group of cellulose derivatives consisting of pregnating, filling or saturating, dressing or the cellulose xanthogenates and the cellulose printing the most varied materials, particularly xanthic acid. The esters produced are free from the textile materials, with a solution of viscose, sulfur. (xanthate), and then treating the material thus 10 The acid anhydride, preferably anhydrides of prepared with the hot acid anhydride. In this 10 aliphatic fatty acids, such as the anhydrides. of case'the cellulose ester is formed in close union the acetic acid, propionic acid, butyric acid, etc., with the material and by further treating the latmay be used as such or in a solvent and the reter by a dyeing operation portions of the fibre action may be facilitated by a catalyst. The which have been covered or associated with the 1 process is a short one. There are obtained accellulose ester are immune to substantive dyecording to the conditions of operation various stuffs but are dyed by cellulose ester dyestuiis, highly esterified celluloses. Since the operation so that multicolor effects can be obtained. By is conducted in the absence of agents capable of gentle treatment with acid anhydride the stage splitting mineral acids and of catalysts having of esterification can be kept so low that the new a mineral acid reaction which degrade the cellumaterial has the advantage that it is insoluble 20 lose, the cellulose esters formed contain the celluin most of the commercial solvents of acetate lose in non-degraded form. In esterifying solid silk. However, by using energetic conditions cellulose xanthates or cellulose xanthic acid the complete esterification can be obtained. By external form is retained, particularly if the acid varying the conditions of operation the lustre of anhydride is diluted with a solvent or used in the thread can be retained or aiiected in any de- 25 moderate proportion, and if solvents are used sired manner. which do not dissolve the cellulose xanthogenates The following examples illustrate the invenand the cellulose esters produced therefrom. tion:-

The process finds application in many techni- Example 1 L cal operations A cotton web is impregnated with a viscose 30 The process is particularly interesting in that it made in known manner dried and treated for 1h permits of wholly or in part esterifying formed hours with acetic anh ydrlde, if desired in $9 lf g gff glif g ag ggf g 321 2532 1; presence of xylene. During this treatment the 5 f th ten'l lfor or the fibrous temperature is raised to 140 C. By this treatw re en Ion o 6 ex ment the web acquires a durable dressing stable structure. For example, one may start from threads of a cellulose xanthate or a celluose xanggzigi g y whlch glves It Stlfi and thlck thic acid made from a viscose solution in the manner usual for making viscose silk but with (0 use of a precipitating bath which, while caus- Viscose made by a known process and in a 40 ing separation of the cellulose xanthate or cellucrude or purified condition is locally applied, for lose xanthic acid wholly or at least in part as instance by printing, to a web or yarn. The masuch, does not regenerate cellulose, or only in terial is dried and then treated with hot acetic part regenerates it; or it may be from cellulose anhydride, the temperature being, for instance,

threads by treatment with alkali and carbon biat the boiling point. The printed places are re- 45 sulfide, while retaining the fibrous structure and served towards substantive dyestuffs but may be avo y dissolving effect during the producdyed vividly by means of acetate silk dyestuffs, tion. BY tr a c ad w th Organic acid the latter leaving the rest of the material unanhydride, for instance acetic anhydride, there dyed In this manner various many colored Example 2 is obtained a thread which possesses the dyeing fects can be obtained. 50

properties of a cellulose acetate, being immune Example 3 towards d1rect dyestuffs; this 1s applicable as an effect thread and has considerably enhanced A skem of cotton 1s immersed for 2 hours in physical properties, particularly in respect of wet an alcoholic potash solution of 20 per cent. and dry tenacity. This tenacity is particularly strength. Then centrlfuged or pressed and for several hours immersed in carbon bisulfide or subjected to the action of vapor of carbon bisulfide. cellulose xanthate acquiring a yellow color and becoming soluble in water. After separating the excess of carbon bisulfide the skein is treated with hot acetic anhydride, for instance for 10 minutes to 1 hour at the boiling point of acetic anhydride, or for a longer time at a lower temperature. The fibrous material thus obtained, the composition of which corresponds approximately with a cellulose diacetate, can be dyed vivid and deep tints by means of acetate sill; dyestuffs but is completely reserved towards substantive dyestufis.

In chloroform, glacial acetic acid and acetone the fibrous material obtained is insoluble, while in pyridine and nitrobenzene swelling occurs but no dissolution.

Example 4 Bleached wood pulp is converted in the usual manner into viscose and the latter is spun. As precipitating bath there is used a solution of an allrali salt or an ammonium salt, acidified with acetic acid, or the bath may consist of methyl alcohol mixed with acetic acid. The precipitated thread, soluble in water, is treated with a solution or 20 per cent. strength of acetic anhydride in toluene. The temperature is ramd to the boiling point of the solution. There is obtained an ester sills, which has the beautiful lustre, excellent wet tenacity and dyeing properties of acetate sills. In chloroform, acetone, glacial acetic acid, pyridine and nitrobenzene the material obtained is insoluble.

. i Example 5 The xanthate thread obtained as described in Example 4': is treated with acetic anhydride at about 100 C., then centrifuged and washed with water. There is thus obtained a lustreless, matte artificial sills. it before the material is washed, the still adhering acetic anhydride is separated by evaporation, the fibre obtained has the usual artificial sill; lustre.

Emmple 6 The skein is gradually converted into silk. The dyeing properties of the material are analogous to those of acetate sills; substantive dyestuffs are reserved, acetate silk dyestufis are absorbed. In acetone, chloroform, glacial acetic acid the material is insoluble.

If instead of the solution of acetic anhydride a solution of 20 per cent. strength of maleic anhydride in xylene is used, there is an increase in weight of the material of about per cent. and a yellowish colored product is obtained which is insoluble in chloroform, glacial acetic acid, acetone. py idine and nitrobenzene, and which has no aihnity for substantive dyestufls.

- What I claim is:-

1. Process for the manufacture of cellulose esters, characterized by treating that group of cellulose derivatives which consists of the cellulose xanthogenates or of the cellulose xanthic acids with aliphatic carboxylic acid anhydrides in the absence of organic acid halides.

. 2. Process for the manufacture of threadlike molded articles of cellulose esters which is characterized by treating threadlihe molded articles consisting of that group of the cellulose derivatives which consists itself of the cellulose iranthogenates or of the cellulose xanthic acids, with allphatic carboxylic acid anhydrides in the absence of organic acid halides.

3. Process for the manufacture of bodies of cellulose esters which is characterized by treating products consisting of that group of the cellulose derivatives which consists itself of the cellulose xanthogenates or of the cellulose xanthic "acids, with acetic acid anhydride in the absence of organic acid halides.

4. Process for the manufacture of cellulose esters characterized by treating that group of the cellulose derivatives which consists of the cellu lose xanthogenates or of the cellulose xanthic acids, with aliphatic'carboxylic acid anhydrides in the absence of organic acid halides, and in the presence of such diluents which are not capable of dissolving the cellulose esters formed.

5. Process for the manufacture of threadlike molded articles of cellulose esters, characterized by treating threadlilre molded articles consisting of that group oi the cellulose derivatives which consists itself of the cellulose nanthogenates or of the cellulose :ranthic acids, with acetic acid anhydride in the absence oil organic acid halides, and in the presence of such diluents whichare not capable of dissolving the cellulose esters formed.

- ANDREAS RUPER'E'I.