Assessment of key issues in the coloration of polyester material

In a previous publication we reviewed some of the most critical issues that affect the coloration and properties of cotton-based textiles [R. Shamey and T. Hussain, Textile Progress 37(1/2) (2005) pp. 1–84]. Today, polyester is still widely regarded as an inexpensive and uncomfortable fiber, but this image is slowly beginning to fade with the emergence of polyester luxury fibers. Polyester fibers currently comprise a commanding 77% share of the total worldwide production of the major synthetic fibers [F. Ayfi, 2003–2004 Handbook of Statistics on Man-Made/Synthetic Fibre/Yarn Industry. Part One, Fibre for Better Living, Association of Synthetic Fibre Industry, Mumbai, India, 2004, p. 177]. More than 95% of all polyester fibers manufactured today is based on polyethylene terephthalate. The dyeing properties of polyester fibers are strongly influenced by many of the processing conditions to which each fiber may be subjected during its manufacturing or in subsequent handling. Significant differences in properties of fibers can therefore arise due to their different processing history. Often, the root cause(s) of a problem in the dyed synthetic material can be traced as far back as the manufacturing process. In order to resolve many of the outstanding issues that commonly occur in the dyeing of this important fiber, a comprehensive review of the issues dealing with the manufacturing history as well as fiber processing conditions, including preparation, dyeing, and finishing is warranted. Although some of the underlying problems are related to common causes such as water quality and imperfections in machinery employed, others are specific to the treatment conditions of the fiber. Such conditions include preparation of ingredients, polymerization, fiber and filament processing conditions, as well as heat setting that can cause problems in the coloration of fiber. This summary analysis complements the rich pool of knowledge in this domain and addresses problems in the dyeing of polyester textile materials in various forms. An overview of various textile operations for polyester is given in the beginning. Then, various key steps and critical factors involved in the production of dyed polyester textile materials are described in detail and problems originating at each stage are summarized.