The leather making process provides the treatment of collagen with various chemicals from the beamhouse to finishing. While the biomass content of collagen is 100%, the biomass content of the final leather article depends on the products or chemicals used in the process and is more challenging for chrome-free leathers, where the organic content is higher in comparison to chrome tanned leathers.

In retanning, vegetable tanning agents and natural fatliquors have been used for a long time. However, in most modern leather articles, they are combined or even entirely replaced with fossil-based, wet-end products for performance reasons.

With a set of 15 selected Stahl wet-end products with a biomass content greater than 25%, including syntans, polymers, fatliquors and a neutralization product, products within the Stahl Ympact® family contain less than 1% volatile organic compounds (VOCs). We achieved a biomass content in crust leather of 92%, even though we applied our own organic tanning system, which is fossil-based. With a standard wet-white crust made with only fossil-based products, the biomass content was 76%.

In finishing, it is even more challenging to positively impact the biomass content of the final leather article, since the vast majority of finishing chemicals are fossil-based.

With seven recently introduced product solutions of renewable carbon polyurethanes for base and topcoats in leather finishing with biomass feedstocks between 26% and 68% content, a finishing was made afterwards.

An automotive leather reaching the set specifications was achieved, having combined small amounts of fossil-based finishing products with the Stahl Ympact® products based on renewable content.

The biomass content in that finishing was 41%. On a 75g piece of crust, the weight of the finishing was 6.1g, of which 2.5g were biobased. That led to an increase of the fossil-based mass by 4% in the final leather article.

To help our customers futureproof their portfolios and value propositions, Stahl has developed and launched Stahl Ympact®. This family of solutions, which is regularly updated and added to, incorporates only future-ready chemical components. The products are tested and certified using the ASTM 6866 carbon isotype method for biobased carbon content, as well as complying with ZDHC’s Restricted Substance List (MRSL 2.0)

Time to seize renewable chemistry’s opportunities – Stahl Ympact® is the technology of tomorrow, today!

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The scientific results of this study were presented by Dr Jochen Ammenn at the 10th Leather Days in Chemnitz, Germany on May 12, 2022.

This article is an advertorial provided by Stahl.