RETANNING OF CHROMIUM-FREE LEATHER

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing chromium-free retanned leather having improved flexibility and color strength.SOLUTION: There is provided a method for preparing chromium-free retanned leather including (a) a process of contacting wet white with a retanning agent of 1% to 8% as a solid weight based on the wet weight of the wet white, selected from i) an aqueous emulsion polymer containing unsaturated ethylene monomer having 1 or more epoxy group of 2 to 35 wt.% based on the weight of the aqueous emulsion polymer as a copolymer unit and having a weight average molecular weight of 2,000 to 100,000, ii) a compound selected from piperazine, piperazine hydrate, a salt of piperazine and a combination thereof, iii) a combination i) and ii), (b) a process of heating the contacted wet white, (c) a process of drying the contacted and heated wet white.