“The use of two microbial enzymes in the soaking and liming noticeably improves the quality of the pelt, reduces the amount of waste and makes the entire process much more efficient,” explains Dr Marc Hombeck, head of New Business in Lanxess’ Leather business unit. The new, enzyme-based technology was developed in collaboration with Danish biotechnology specialists Novozymes, who also manufacture the two pure enzymes by means of bacterial fermentation.

Complete rehydration

Peltec X-Zyme S, which is used in the soak, is a glucosidase – ie a carbohydrate-splitting enzyme – with customised properties which include rapid opening-up and accelerated rehydration of the hide. This means that excellent soaking results can be obtained after just four to six hours. And as the enzyme has no proteolytic activity, the soaking process can be extended – eg overnight – without damaging the collagen.

Gentle unhairing

In the liming process, Peltec X-Zyme U, a specific protease with high selectivity for pre-keratin, is applied to remove the hair and the epidermis. This product primarily targets the basal membrane of the epidermis, thereby loosening the hair roots and preparing the subsequent unhairing. There is no need for reductive chemicals that are required in conventional hair-saving processes and yet Peltec X-Zyme U tackles the residual hair root problem. Further advantages of the new process are a lower effluent load and reduced need for chemicals.

A mature process

Production-scale trials of both, the products and the process, at customers’ plants have proven their efficiency and reliability. The X-Zyme process is robust and can be controlled very accurately and reproducibly by means of parameters such as the temperature and the pH of the float. “The new process ideally meets all the main requirements with regard to productivity, product quality and environmental protection,” says Hombeck.

Sustainable leather with X-Zyme

Compared with conventional processes, it reduces the need for wetting agents (surfactants) and liming chemicals such as lime, sulfur compounds and amines. This is resulting in more favourable wastewater values like sludge, COD, sulfide and nitrogen. In addition the rapid opening-up of the hide in the soak and the reduced amount of alkali ensure high-quality pelts.

The X-Zyme process was developed specially for the Peltec product line, which in turn is geared specifically to the requirements of the beamhouse. The range includes leather chemicals for all four process stages – soaking, liming, deliming and bating. You will find more detailed information at www.lanxessleather.com

The Leather business unit belongs to Lanxess’ Performance Chemicals segment, which achieved total sales of €2.2 billion in fiscal 2012.