GB384403A - Process for increasing the affinity of cellulose esters for dyestuffs - Google Patents

Abstract

Cellulose esters having an increased affinity for dyestuffs are produced by esterifying cellulose by means of a simple anhydride of a mono-carboxylic acid containing nitrogen, such as cyanacetic anhydride, amino-benzoic anhydride or the like, or by means of a mixed anhydride of acetic acid and a mono-carboxylic acid containing nitrogen. Alternatively, there is added to the cellulose ester whose affinity is to be increased, a cellulose ester containing nitrogen obtained as described above. In the case of cellulose esters containing cyano groups, the affinity for dyestuffs, particularly direct dyestuffs, is further increased by subsequent treatment with an oxidizing agent, a saponifying agent, or both, whereby the cyano groups are converted into acid amide or carboxyl groups. In an example, the cellulosic material is treated with a mixture of glacial acetic acid, the mixed anhydride of cyanacetic acid and acetic acid, and acetic anhydride, in presence of sulphuric acid. The mixed anhydride used above may be replaced by the simple anhydride of cyanacetic acid or of aminobenzoic acid, or by the mixed anhydride of aminobenzoic acid and acetic acid. Specifications 344,488 and 369,017 are referred to. The Specification as open to inspection under Sect. 91 refers also to the application, in place of the organic anhydrides containing nitrogen, of the anhydrides of dicarboxylic acids, e.g. the anhydride of succinic acid or an alkyl substituted succinic acid, or of a mixed anhydride of a dicarboxylic acid and acetic acid, e.g. a mixed anhydride of malonic acid and acetic acid. The cellulose may be replaced by "alcohols other than cellulose and also by compounds which contain an amino group in place of the alcoholic hydroxyl group." This subject-matter does not appear in the Specification as accepted.