GB836808A - Improvements in or relating to the production of leather - Google Patents

Abstract

836,808. Fat-liquoring leather. DU PONT DE NEMOURS & CO., E. I. July 5, 1956 [July 5, 1955; March 30, 1956], No. 20912/56. Addition to 762,997. Class 76. The complex compounds of the Werner type in which a trivalent nuclear chromium atom is co-ordinated with carboxylic acids groups having at least 10 carbon atoms as described in the parent Specification are applied to the leather before, or preferably after, conventional fat-liquoring. Conventional fat-liquoring oils named are neat's foot, coconut, fish, sperm, castor, mustard seed, tea seed, lard, corn, olive, linseed, rapeseed, soya bean and tallow oil which may be emulsified and/or sulphated. The pH is adjusted to 3-3.5 by the addition of a monobasic acid such as formic acid before adding the chromium complex. In examples: (1) chrome-tanned cowhide is split, retanned with Quebrancho extract, fat-liquored with sulphated neat's-foot and cod oil and subsequently egg yolk, dyed, then treated with formic acid and finally stearato chromic chloride in aqueous iso-propanol; (2) cowhide is tanned and retanned as in (1), fat-liquored with sulphated neat's-foot and fish oil and egg yolk, dyed and finally treated with stearato chromic chloride in aqueous iso-propanol; (3) steerhide is tanned in a manner related to (1), retanned with a mixture of Quebrancho and wattle, dyed, fat-liquored with cationic sperm oil, sulphated fish oil and emulsified fish oil and finally myristato chromic chloride.