Abstract

Raw hides are a rich source of fats and proteins that may serve as metabolic substrates for microorganisms, especially bacteria and fungi. These micro-organisms that are capable of invading the hide for its nutrients are present on the fresh hide during harvest as well as from the surrounding environment during and after processing at the tannery. Fungal attack on tanned collagen changes the chemical composition of the pelt in the area of growth. These changes along with fungal pigmentation will usually cause discolouration or spots of various colours depending on the infesting organism. This fungal discolouration is difficult to correct and can spoil crust or finished leather. To protect tanned hides (such as wet-blues, vegetable-tanned, free-of-chrome, or oiltanned leathers), a fungicide is added during the pickle or tanning process. The fungicide must survive the conditions of tannage and adhere to the surface of the tanned hide to protect the leather from the time the tanning process is complete until the tanned hide is processed further and finished into a dry leather product. In order to be effective for the leather industry, the fungicide should be stable under acid conditions, reasonably stable to UV-light, relatively unreactive with other tanning process chemicals, and have a high affinity for the hide or skin substrate.

Historically the leather industry made use of chemistries such as organomercurials and chlorophenates which are now banned because of high level dangers regarding environment and human exposure. In recent decades these have been replaced with effective and safer chemistries such as: 2- (thiocyanomethylthio)benzothiazole (TCMTB), 3-iodopropynylbutylcarbamate (IPBC), n-octylisothiazolinone (OIT), diiodomethyl-p-tolylsulfone (DIMTS), and some phenolics.

A need exists in the leather industry for new compounds that not only are effective fungicides, but also survive the chemical environment of the tanning process. In addition, a valuable strategy for microorganism control is to combine two or more microbicides to expand the spectrum of control as well as to exploit potential synergies in the biocidal actions. This paper describes chemical, biological, and toxicological properties of a new antifungal compound in a class of chemistry known as cyanodithiocarbimates. A patent for the use of this chemistry as a fungicide in the leather industry has been granted.