Influence of Substrate Type on Level Dyeing of Acrylic Yarn Packages

Abstract

In an earlier paper [1], the influence of flow rate, ramp (constant rate of temperature rise) and package density on the rates of dyeing of two basic dyes on Ex/an, and on the levelness obtained in the resulting dyeings, was investigated, and a relationship was derived to link these factors quantitatively. This work has now been extended to cover the behaviour of various basic dyes on Exlan and other acrylic fibres, under conditions expected to give borderline levelness. It has been shown that the shape of the rate–of–dyeing curve depends on the type of acrylic fibre and, to a lesser extent, on the cationic retarder used, but not on dye type within the group of CV2. 5–3. 5 basic dyes examined. The response of dyeing rate and degree of unlevelness to deliberate variations of ramp, as demonstrated in the previous work on Exlan, is now confirmed on Cashmilon. Evidence of a different type of random unlevelness, not related directly to dyeing rate, was also obtained from dyeings on the various fibres at a slow ramp.

Bulk–scale Dyeing of Acrylic Yarn Packages

“…Visual assessment of the knittings prepared from the dyed packages was carried out as described previously [ 1,2] , The four assessors were unanimous in assessing the Orlon dyeing as level (within commercial tolerance limits) and the Cashmilon and Exlan dyeings as unlevel (completely unacceptable in this respect).…”

“…Recent investigations of the dyeing of acrylic packages with basic dyes have been concerned with the response of dyeing kinetics and degree of unlevelness to various factors. Those discussed included: rate of temperature rise [ 1,2] , fiow rate and package density [ 1 ] , substrate type, dye and cationic retarder [2], package geometry and type of package support [3] . In the course of this work it was decided that a series of bulkscale trials should be carried out on several acrylic fibre types, in order to evaluate on a larger scale some of the conclusions emerging from the earlier work.…”

Does dyeing practice need dyeing theory?

“…The behaviour of several basic dyes on various acrylic fibre types was assessed under dyeing conditions that were expected to give borderline levelness [23]. The shape of the rate‐of‐dyeing curve depended on the type of acrylic fibre and, to a lesser extent, on the cationic retarder used, but not on basic dye type within the range of compatability values (CV) 2.5 to 3.5 examined.…”