New preservatives for leather production

Preservatives are an essential ingredient in the leather production process, in particular to protect wet-blues, wet-whites, crust and vegetable leather against damage caused by mould. Nowadays, preservatives are no longer selected simply on the basis of their effectiveness and cost. Ecological and toxicological aspects, statutory requirements, official regulations and approval by various authorities also play an important role in such decisions. The range of leather preservatives produced by Bayer Chemicals, a division of Bayer AG, is geared to the local requirements in each tannery and to the official regulations. In response to specific regional demands, Bayer have now developed the new products Preventol OT-L and Preventol CT-L. These preservatives are optimised formulations in which the phenolic active ingredients PCMC and OPP have each been combined with one other active ingredient. PCMC (p-chloro-m-cresol) and OPP (o-phenylphenol), two of the most widely investigated active ingredients, form the basis of the most important biocidal formulations. Preventol WB-L, which is a combination of the two active ingredients, has been used successfully in tanneries throughout the world for over twenty years. Its affinity to the collagen fibre, the fact that it is difficult to wash out, its special mode of action by which the microbial cell is attacked directly (membrane-active mechanism) and, not least, its broad and well-balanced spectrum of activity coupled with favourable toxicological properties have made it one of the most successful fungicides for wet-blues. Preventol WB-L has now been combined with Na-pyrithione to optimise the already comprehensive spectrum of activity. The new product, Preventol WB plus-L, has become firmly established on the market within a very short time and is already being widely used in tanneries. The range of water-based, surfactant-free formulations is rounded off by Preventol C 40-L, which has PCMC as its active ingredient. All three products - Preventol WB-L, Preventol WB plus-L and Preventol C 40-L - have US EPA approval. When used for preserving leather, these formulations are non-sensitising. The active ingredients contained are biodegradable. Preventol C 40-L also complies with the special regulations that apply in California. The new OPP-based Preventol OT-L is free of adsorbable organic halogen compounds (AOX) and has an emulsifying system that improves the penetration of the active ingredient. Although only recently introduced onto the market, it has already seen interest in tanneries in central Europe, where there is a demand for a PCMC-free fungicide because of the general problems with AOX. Preventol CT-L, an OPP-free emulsifier formulation based on PCMC, is a reliable alternative to Preventol OT-L. Wherever there is a demand for TCMTB-free formulations, the established products Preventol WB-L, Preventol WB plus-L and Preventol C 40-L and the new developments Preventol OT-L and Preventol CT-L are the products of choice on account of their long-term effectiveness, reliability in application provided that the recommended health and safety measures are adhered to, and good ecological compatibility.