Influence of Retanning Materials with Different Properties on the Flammability of Leather

During leather making, plenty of materials are added to the hide fiber in some treatments including tanning, retanning and fatliquoring. Most of these processes and materials impact the flammability of leather. In this paper, effects of properties of retanning agents on leather flammability were emphatically discussed. First, six retanning agents were selected, including Chromitan, vegetable tannin, glutaraldehyde, syntans and organophosphorus agent, to treat cattle wet blue with routine processes. Then the flammability of the retanned and the control leather was evaluated by vertical flame test, oxygen index test and smoke density test. The surface area of the retanned leather was also measured by nitrogen adsorption method. The results show that the effect of different properties of retanning agents on leather flammability varies greatly. This is mainly due to three aspects: the combining ways between retanning agents and leather fibres, the filling ability of retanning materials to leather and the flame resistant element contained in retanning agents. These results may offer some guidance for the choices of retanning agent for fire-resistant leather.