GB1167641A - Improvements in or relating to Tanning - Google Patents

Abstract

1,167,641. Softening, stabilizing and/or tanning hides, skins &c. M. SITTENFIELD. Jan.2, 1967, No. 149/67. Heading C6C. In a process for softening and stabilizing and/or tanning proteinaceous fibrous material, such as animal pickled or de-pickled hides and skins, the material is impregnated with an N, N<SP>1</SP> - bis (alkoxymethyl) uron, i.e. 3, 5 -bis (alkoxymethyl) tetrahydro - 1, 3, 5 - oxdiazin - 4 - one, having the general formula: in which R and R<SP>1</SP> are alkyl groups, which may be the same or different, and may each contain between 1 and 4 carbon atoms. Impregnation may be effected by soaking hides, at room temperature, with an aqueous solution of the uron, e.g. containing sufficient alkali metal salt (such as sodium chloride and/or sodium acetate or sodium sulphate) to prevent swelling of the hides, and having a pH between 3 and 12. Soaking may be accompanied by agitation. The aqueous solution may contain at least 2À5% of the uron based on the weight of the hides. The aqueous solution may contain 50%, by weight, of the uron. Hides may be soaked and agitated for two hours in said aqueous solution at a temperature of 25‹C, and may then be substantially dried, as by squeezing between pressure rollers, and then immersed in an aqueous alkaline solution until the molecular structure of the hides becomes substantially cross-linked, polymerized and tanned, e.g. for 10 hours without agitation. A suitable alkaline solution is an aqueous 3%, by weight, solution of sodium carbonate. Leather produced according to the invention has a shrink temperature of the order of 88‹ C. The process may be accelerated by raising the temperature, but this should not exceed a temperature 15‹C. below the shrink temperature. Alternatively, the process may be accelerated by using ultrasonic sound waves. The uron solution may be applied to the hides by spraying, brushing, painting or calendering operations. The process according to the invention may be used for softening and straightening wool and animal hairs, and for producing a soft-smooth "feel" on animal skins.