InnoLeder

The tanning and dyeing of leather has hardly changed for many years and requires many resources. On average, 250 m³ of water and 2.5 tons of chemicals are used to produce one ton of leather, of which around 20% remains in the leather. The development of resource-efficient processes to avoid excess chemicals is crucial for sustainable leather production.

Fraunhofer UMSICHT has already developed an innovative process for leather tanning without wastewater that uses CO₂, is patented and has been demonstrated on a pre-industrial scale (Cleantan). There is also a water-free dyeing process using CO₂ as a solvent for dyes, which has also been patented (RowaLef).

The “InnoLeder” research project aims to increase the maturity of this new, water-free dyeing technology. The focus is on developing a color matching system to ensure high color flexibility. The use of compressed carbon dioxide instead of water and conventional dyes not only greatly reduces the consumption of resources, but also significantly reduces the environmental impact of waste water and chemicals.

The new process to be developed in the "InnoLeder" project makes it possible to reduce dye consumption by over 90% using supercritical CO₂, which saves considerable resources and has less impact on the environment. Traditional dyeing processes mean that the dyes used end up in waste water. Water and chemical dyeing auxiliaries are also not required, making the process more environmentally friendly and even eliminating the wastewater problems of conventional dyeing

The new process also allows leather to be dyed after cutting so that dyed leather is no longer wasted. It is even possible to dye finished leather products. It is important for the industry to be able to mix different colors in order to produce many different shades. In the project, the researchers are therefore analyzing the dye absorption capacity and color solubility as well as the cleaning effort between color changes. The color flexibility can be carried out by annexes with volumes between 5 l and 1700 l from Fraunhofer UMSICHT. The surface-dyed leathers should also achieve the highest rub fastness levels and the dyes used should be able to be used for dyeing with virtually no loss.   

In addition to the ecological benefits, the compliance office-based process also saves significant costs for the leather industry. Operating costs are reduced as less dye is required and chemical dyeing auxiliaries and large quantities of water for the dyeing process are eliminated.

The project makes an important contribution to the sustainable transformation of the leather industry by combining ecological, economic and technological advantages.

The successful implementation and market launch of the CO₂-based dyeing process offers the European leather industry the opportunity to position itself as a pioneer in the section of sustainable production. This can lead to a stronger market position as more and more consumers and business partners prefer sustainable products.