Improvements in or relating to the spin dyeing of cellulose acetate

摘要

In the spin-dyeing of cellulose acetate there is used an anthraquinone dyestuff which is insoluble in the spinning solution and has the general formula: wherein X, X1, Y and Y1 represent hydrogen or identical or different substituents selected from fluorine, chlorine or bromine and Z represents the divalent radical of benzene-1.4-dicarboxylic acid or of 1.11-azo- or 1.1 1-azoxy-benzene-4,41-dicarboxylic acid or the divalent radical of an ethylene -1. 2-dicarboxylic acid which may be substituted by chlorine or methyl. The dyed spinning solution may be prepared by dispersing in a portion of the cellulose acetate spinning solution a relatively large proportion of the dyestuff, grinding the suspension to reduce the dyestuff particles to the required size, and mixing a minor proportion of the relatively concentrated suspension with a major proportion of the undyed spinning solution. Alternatively the dyed spinning solution may be prepared by grinding or kneading a mixture of the dyestuff and cellulose acetate in the presence of an organic solvent which dissolves the celluose acetate but not the dyestuff, and which is either miscible with water in all proportions or contains a component miscible with water in all proportions, precipitating the cellulose acetate by addition of water, isolating the dyestuff and cellulose acetate from the mixture and adding the isolated solids mixture to a spinning solution solvent for the celulose acetate. The dyed spinning solution may be subjected to a final grinding before spinning. Both secondary cellulose acetate and cellulose triacetate may be treated.