Enhanced chrome tanning process

Data di pubblicazione

08-05-2018

Codice

CH.18.011.A

Data di priorità

19-02-2018

Fase

National phase

Titolare

Politecnico di Milano

Dipartimento

Department of Chemistry Materials and Chemical Engineering

Autori

Luca Magagnin, Maurizio Masi, Filippo Rossi, Eugenio Gibertini, Giulio Rovere

Descrizione

The invention relates to an electrochemical tanning process of hides to obtain durable leathers. It provides the possibility to employ different olating agents, not only metal salts [e.g., sulfate or chloride salts of chromium (III), iron (III), zirconium (IV), titanium (IV), aluminum (III)] but also tannins or aldehydes. The olating agents react with the carboxylic moieties in collagen, resulting in multiple hydrogen and M-O-M (M, metal complex) bonds that are active in the crosslinking of the sub-units in collagen. The process involves three steps: (a) pickling phase, when the tanning bath is acidified to pH values lower than 3 (acid pH is needed to favor olating agent diffusion inside the hide); (b) tanning phase, when hide is immersed in an acidic solution containing the olating agent; (c) basification phase, aiming to promote the olation reaction and stabilize the crosslinking between collagen and olating agent. By the application of an electric field in each of the three steps, process time and required bath volume are reduced. Introducing an anodic membrane between the two electrodes results in: - pH lowering of the anodic compartment; - pH raising in cathodic compartment. The voltage applied at the electrodes is a function of the distance between them and the width of the hide to be tanned.

Campo di applicazione

Leather tanning

Vantaggi

- The electrochemical process significantly reduces required time to obtained tanned leather; - Employment of a very small bath volume to hide area ratio; - Possibility to use different olating agents other than chromium (III) salts.

Stadio di sviluppo

Experimental

Contatto

licensing.tto@polimi.it