POLYMERIC COATINGS CONTAINING ANTIOXIDANTS TO IMPROVE UV AND HEAT RESISTANCE OF CHROME-FREE LEATHER

The most common method of preserving raw hides is brine curing with sodium chloride. However, this process has three important disadvantages: first, the length of time that it takes, which is a minimum of 18 hours; second, the insufficient degree of curing reached in some hides due to an overload and possibly the low efficiency of the brine raceway; and finally, the environmental impact associated with the discharge of large quantities of electrolytes in the soaking step. Our long term goal is to address all three issues. Initially, we have carried out a study of the salt uptake and its diffusion mechanism in order to attempt a reduction in the curing time. A continuous reaction mathematical model of a closed one dimensional system that describes the diffusion of sodium chloride in the hide during the curing process was chosen in the search for the optimum brine curing conditions such as the optimum brine concentration and percent float. The effect of these two parameters on the values of transport coefficient λ was reported. Brine diffusion into the hide was tracked by measurement of the chloride concentration of the residual brine solution. In addition, a piece of hide was cured with a fluorescently labeled brine solution and analyzed by means of epifluorescent microscopy for direct visualization of the sodium location within the hide.