METHOD OF MANUFACTURING HEAT-RESISTANT RUSSIA UPPER LEATHER FROM WET- SALINE CONSERVATION CATTLE SKIN Russian patent published in 1999 - IPC

FIELD: leather industry. SUBSTANCE: invention concerns chrome-dubbing of Russia leather. Skins are soaked in sodium sulfide solution for 16-18 hr, after which integrated process is performed involving unhairing liming in sodium sulfate and calcium hydroxide solution to which sodium carbonate was added. Liming liquid is strengthened by single addition of calcium hydroxide 12 hr after the beginning of liming process and twofold addition of sodium sulfide 2 and 12 hr after the beginning of liming process. Resulting offal is then delimed with ammonium sulfate for 1 hr 40-45 min at ammonium sulfate concentration 2.5-3.8% based on the weight of offal at fatty acid index 1.5-2.0. Skins are bated with protosubtelin for 10-15 min, pickled in sulfuric acid solution, chrome-tanned, and neutralized with sodium bicarbonate at its concentration 2.0-3.0% and fatty acid index 1.5-2.0. Further, skins are dyed in a dye containing direct black (0.8%) and water-soluble nigrosine (0.8%) for 1.5-2.0 hr at fatty acid index 1.2- 2.0, dubbed with natural and synthetic fats, hydrophobized, after- tanned, soaked and dried to leather moisture 25-28% while simultaneously applying additional soaking. EFFECT: enhanced process efficiency and improved quality of leather. 9 cl