GB310823A - Process for the treatment of hides in the production of leather - Google Patents

Abstract

310,823. Nance, C. W. Dec. 1, 1927. Treating hides with liquids.-Hides to be treated with liquors for soaking, liming, deliming, and tanning are subjected to a high vacuum in an autoclave containing the liquors and provided with pipes for circulating the liquors on the application of heat. The apparatus consists of a number of autoclaves 1 each provided with a false bottom 13 and with a number of circumferential pipes 12 connected to a perforated pipe 11 arranged near the top of the autoclave. The lower open ends of the pipes 12 extend below the bottom 13 into the liquid, and, on the application of heat and vacuum to the autoclave, conduct the liquid to the pipe 11 from which it is sprayed on the hides. The autoclaves are connected to a foam-trap 8 wherein vertical spiral and horizontal perforated plates separate any liquid drawn out of the autoclave. The foam-trap can be discharged, and the autoclave 2 connected by valve-controlled pipes 3 to the autoclaves 1. Connected to the autoclaves is a cylinder provided with a screw-operated ram 21 for applying increased pressure. The hides are hung in an autoclave and first subjected to a high vacuum to remove any moisture or gas held therein. Water containing a small amount of sodium sulphide is drawn into the autoclave until the hides are covered, and the whole subjected to a high vacuum and a temperature of 90‹ F. The water is then run off, and the hides then subjected to a similar treatment with lime liquor. The hides are removed, unhaired, fleshed, and scudded, and then replaced in the autoclave and treated under similar conditions with boric acid solution and water. The hides are subjected to a high vacuum to remove any air and then to three different tanning-solutions of increasing density and at temperatures of 90' F., 100' F., and 130‹-140‹ F. respectively, the solutions being drawn into the autoclave through chambers in which the gases are withdrawn. During the tanning, the hides and liquors are first subjected to a high vacuum and then to an increased pressure applied by the ram 21. The hides are washed, and dried at a temperature of 120‹ to 140‹ F., and, if desired, impregnated with a waterproofing substance.