Benninger-Küster Promote CPB Salt-Free Dyeing System To Save 50% Of Water And 90% Of Energy In €1 Bn Egyptian Textile Project

Image Courtesy of Benninger

This year Benninger is celebrating its 160th anniversary.

This anniversary stands primarily for 160 years of commitment to textiles, but also for 160 years of responsibility towards sustainable textile production.

Thanks to consistent innovation and the continuous improvement and further development of our products, processes and services, for the past 160 years the name Benninger has stood for textile finishing plants that are particularly resource-efficient.

A recent success  was the signing of a supply  contract with Cotton and Textile Industries Holding Company, Egypt, which kicked off the implementation of a huge modernization program for the Egyptian textile industry at ITMA 2019.

Benninger is proud to be able to participate in this project, which has an approximate total value of €°1°billion, together with other market players in the textile industry in Switzerland and Germany

At ITMA Benninger presented the Benninger-Küsters Cold Pad Batch  dyeing centre for knitwear and woven fabrics - the only salt-free cold dyeing process, Salt-free dyeing without the use of energy is only possible using the cold pad batch (CPB) dyeing process.

Reactive dyes are the family of dyes generally used to dye cotton, viscose, and other cellulosic fibres.

However, reactive dyeing requires vast amounts of salt, water and energy.

The process is also quite inefficient, leading to low fixation rates (approximately 75 %). This means that repeated rinses are needed to remove the unfixed dye, increasing both water and energy use (as rinse water is often heated).

Wastewater produced from reactive dyeing contains high levels of both salt and dye, which is difficult to treat.

Cold pad batch dyeing (CPB) is an alternative method of reactive dyeing that uses fewer resources.

With CPB there is no need to apply heat during the process, and no salt or humectants are needed. 

However, the rate of fixation depends on the ambient temperature, so in countries where there is a big difference between summer/winter temperatures, it is good practice to carry out dye fixation in a heat-regulated room. 

The contents of the dye pad trough need to be prepared just before dyeing starts to prevent hydrolysis and to get good levels of dye fixation. This is why the dye solution and alkali solution are usually pumped to the dye trough separately and mixed immediately before dyeing – and there is often the use of a chiller to keep the dye liquors cool.

High-quality adjustable rollers/mangles are needed in order to get uniform dye application and prevent side-to-side variation (resulting in fabric rejections). After dyeing, the fabrics can be washed off, preferably on an efficient counter-flow wash range.

This process is also becoming increasingly popular in tropical and subtropical regions, where water and energy are at such a premium, and is particularly relevant to the Egyptian project, providing a sustainable and efficient fabric processing system.