KARL MAYER ROTAL, the site with the KARL MAYER Group's denim center of excellence, has developed GREENDYE, a technology that offers both: Sustainability and at the same time more economic efficiency than conventional plants.

The innovation was launched in 2019. The first sale followed this year. The premiere machine goes to Taiwan, to the innovative global player NIEN HSING.

A company with a sense of responsibility

The fully integrated denim manufacturer has written the topic of sustainability at the top of its corporate agenda. Already in 2015, a development and innovation center was established to promote ecological finishing processes. In 2017, NIEN HSING's corporate policy committed to reducing its ecological footprint and using clean production technologies for this purpose. In warp preparation, the environmentally conscious denim player aims to improve its eco-balance, especially with KARL MAYER's GREENDYE unit. "We got to know the pilot plant at KARL MAYER ROTAL and studied its operation in detail in terms of output, costs and sustainability. The results convinced us." says Chairman Chen, Chao Kuo.

With GREENDYE, indigo dyeing is two times cleaner and at the same time three times more efficient than with the processes of conventional equipment. The basis for the excellent performance is the use of nitrogen (NOX) technology to control the chemical dyeing process.

Tripling of dyeing efficiency, halving of resource consumption

The nitrogen atmosphere temporarily prevents the necessary oxidation of the indigo dye. In the NOX reactor, the indigo dye has time to create a more solid physical bond into the fiber composite, adhere there and be fixed.

It is also possible to increase the indigo concentration in the dye bath. These effects enable the yarn to absorb three times more dye than in case of conventional processes.

Further advantages result from the design of the dyeing vats. A high-flow, low-speed indigo circulation system and a design that avoids turbulence and surface foaming significantly reduce chemical consumption. A saving of up to 50% of hydrosulphite and caustic soda – the main environmental polluters of the process - and thus a halving of the gray water footprint is possible.

A reduction of 50% is also possible in the final washing water consumption. Thanks to the NOX reactor, the GREENDYE system requires only three dyeing baths instead of nine - like conventional systems - to achieve the same indigo dye shade, with correspondingly lower water consumption. In addition, the washing process is more economical due to the higher fixation of the indigo dye on the fiber.

Fewer dyeing baths also mean shorter dyeing sections. The difference in length is two-thirds and reduces the amount of yarn waste.

The reduction of daily water and chemical consumption as well as waste water and yarn waste optimizes not only the environmental balance but also the production cost in indigo dyeing. In addition, the operating costs are extremely low. Compared to traditional indigo dyeing systems, the GREENDYE system requires less space due to its shorter design, less maintenance, less time for operation and less spare parts for the same output.