Abstract

A combination of inhibitors, namely a mixture of 1.0mmol of 3(2)-t-butyl-4-hydroxyanisole, 0.01 mmol of ascorbic acid, and 0.001mmol of collagen peptide exhibiting complete inhibition of C6+ formation on a laboratory-scale, was applied to produce chrome-tanned upper leather without formation of Cr6+ in the actual manufacturing line of a tanner. In this study, the following two methods were used for application of the combined inhibitor; (1) spraying with the combined inhibitor solution before finishing, using twice the volume of the dry leather weight after fat-liquoring; and (2) coating with base-coat containing the combined inhibitor before top coating in the finishing process, using twice the volume of the dry leather weight. Each inhibitor-treated leather contained chemical components similar to those of typical leather produced without the combined inhibitor, and exhibited perfect inhibition of Cr6+ formation, even if heat-aged. In addition, the physical strength of the inhibitor-treated leathers was higher than that of leather produced usually without inhibitor. In particular, the surface strength (ball burst) of the treated leathers was twice that of the untreated leather. These results indicate that this combination of inhibitors could be effectively applied to industrially produce Cr-tanned leather not only without C6+ formation but also with an improved physical strength.