Description

Textile colorants consist of dyes and pigments for the coloration of yarns, fabrics and garments. These colorants are applied either by dyeing or by printing. In recent times, there have been a number of advances in textile printing equipment, mainly in digital printing methods. For example, digital printing is the fastest growing system of all textile printing processes. Between 2000 and 2005, the output of digital printed textiles increased by 300%. Some industry experts believe that digital printing could account for 10% of the entire textile printing sector by the early part of the next decade. Innovations in printing and dyeing technology have led to a number of changes in the textile colorants sector, including shorter production times, smaller batch sizes, lower production costs and improved manufacturing efficiencies. Also, in the past, dyers and printers have found it especially difficult to colour certain types of fibres-especially those made from synthetic materials such as polypropylene, and fibres which naturally consist of keratin, such as wool or fur. However, these types of fibres can be treated with plasma gas before dyeing to help the dyes to bond to the substrate. In printing, new ink equipment such as valve-jet systems-which are available on J Zimmer Maschinenbau's ChromoJet 400 and 1200-enables images or designs to be printed on to wool or fur without loose fibres blocking up ink dispersion nozzles. Perhaps one of the strongest drivers for change is pressure for dyeing and printing methods to become more environmentally friendly. The process of electrochemical dyeing-which reduces chemical waste and decreases water wastage-won an award for research and development in 2006. In dyeing, key technological advances include: non-aqueous dyeing systems such as supercritical carbon dioxide (CO2 ) dyeing; the use of ionic liquids; electrochemical dyeing; cationisation; and plasma gas treatment. Digital technology offers opportunities for companies to measure and monitor colours better during dyeing through the implementation of integrated colour management software packages. Netherlands-based Stork Prints, for example, has developed its own colour control concept to integrate the whole process.

Table of Contents

SUMMARY INTRODUCTION KEY DEFINITIONS IN TEXTILE COLORANTS Technological advances in dyeing processes Non-aqueous systems Ionic liquids Electrochemical dyeing Cationisation Plasma gas treatment Types of dyes Vat dyes Reactive dyes Disperse dyes Acid dyes Methods used in printing Screen printing Engraved roller printing Heat transfer printing Digital printing Technical improvements in digital printing KEY TRENDS IN THE MARKET FOR TEXTILE DYES Environmental pressures Developments in dyes and inks ENVIRONMENTALLY FRIENDLY INNOVATIONS Non-aqueous systems Supercritical carbon dioxide (CO2) Ionic liquids: another non-aqueous dyeing method Electrochemical dyeing Cationisation: eliminating the use of salts in reactive dyeing Plasma gas treatment: treatment of the substrate before dyeing takes place