Dyeing and fastness properties of phthalimide‐based alkali‐clearable azo disperse dyes on poly(ethylene terephthalate)

Abstract

The properties of a series of phthalimide‐containing azo disperse dyes and azo dyes with N‐methyl phthalimide moieties in their diazo component were investigated and compared when used to colour polyethylene terephthalate. The N‐substitution of the phthalimide gave a hypsochromic effect on the colour change and better colour yields on poly(ethylene terephthalate) fabrics, probably because of the electron‐donating property of the methyl group and the higher hydrophobicity of phthalimide‐containing azo dyes compared with those containing phthalimide moieties. The results show that phthalimide‐based azo disperse dyes have excellent dyeing fastness properties and that high wash fastness can be achieved using alkali clearance. This alternative clearance method is important for reducing the environmental impact of the dyeing process by replacing reductive clearing and, in particular, by removing the need for sodium hydrosulphite, which creates a high biological oxygen demand when released in conventional disperse dyeing effluent and which generates aromatic amines.

Erratum: Progress towards a greener textile industry†

“…This was first achieved by ICI with the availability of disperse dyes that carried carboxylic ester groups, namely the Procilene PC and later the Dispersol PC dyes, the latter being used as ground shades for illuminated discharge printing styles [62]. More recently, phthalimide‐ and naphthalimide‐containing azo disperse dyes have also been shown to yield dyeings on polyester with good wet‐fastness properties (although the authors did not quote any light‐fastness data) when using only an alkali after‐clearing treatment [63,64].…”

The roles of elevated temperature and carriers in the dyeing of polyester fibres using disperse dyes: Part 1 fundamental aspects

“…As their name suggests, such dyes are designed to be readily removable from dyed polyester materials under hot aqueous alkaline clearing conditions (eg 70‐80°C, sodium carbonate and/or sodium hydroxide 8,443,586,587 ), thereby obviating the need for reducing agents. Alkali‐clearable disperse dyes continue to attract research attention 579,588–610 …”

Hetarylazopyrazolone Dyes Based on Benzothiazole and Benzimidazole Ring Systems: Synthesis, Spectroscopic Investigation, and Computational Study

“…The ease of availability of raw materials and ease of preparation [1], wide range of uses as dyestuff [2,3], advanced applications such as liquid crystal displays (LCDs) [4], nonlinear optical (NLO) devices [5], dye-sensitized solar cells (DSSCs) [6], optoelectronic systems [7,8], and wide application areas in biological and medical studies [9] are all desirable characteristics of azo dyes.…”