Articles - Leather Technology Magazine Nº72

Application of synthetic retanning agents in chrome-free leathers

Authors: Ramón Palop ¹, J. Carlos Karachov ², Joan Parareda ¹, Olga Ballus ^1
1 Tanning Laboratory, Cromogenia Units S.A.
Address: Zona Franca. Sector E. Calle nº 50, 08040, Barcelona, Spain
² Tanning Laboratory, Units Sudamericana S.A.
Address: Santa María del Buen Ayre 362/4, Buenos Aires, Argentina

Application of synthetic retanning agents in chrome-free leathers

Work presented at the 2nd National Technical Symposium of the Tanning Industry, Buenos Aires. November 21th, 2008

ABSTRACT

The present study comprises two parts. In the first part, we assess the influence of eleven synthetic retanning agents of different nature on pickled leather. In the second one, we evaluate the physical-chemical and organoleptic properties of leathers previously tanned with aldehyde. Finally, we optimise their application, proposing the synthetic agents appropriate for chrome-free automotive upholstery.
The application to pickled leather evidences the influence of the tanning capacity of each of the products used on the physical and organoleptic properties. These properties are affected basically by three factors: retanning agent acidity, condensation degree, and chemical nature.
In the application to aldehyde-pretanned leather, it was found that non-retanned leathers are softer, but very empty. Retanning agents derived from hydroxydiphenyl sulfone and vegetable phenol provide the best physical and organoleptic properties. The best physical strength properties are attained with sulfonic phenol and vegetable phenol.

Key words: retanning agents, synthetic agents, wet white.