Résumé : |
Four water-soluble crosslinking agents have been examined as tanning agents for sheepskin and cattlehide. Three were dicarbamoylsulfonates made by bisulfite addition to diisocyanates, the fourth was terephthaloyl thiosulfate. All four were tested as primary tannages, and the bisulfite adducts were also used to retan slack chrome- and zirconium-tanned leathers.
Each of the bisulfite adducts tanned the hides and skins, as shown by an increase in shrinkage temperature and resistance to enzymic digestion, but subjective and mechanical testing revealed various deficiencies in the resultant leathers. Terephthaloyl thiosulfate had tanning action.
Better results were obtained using the bisulfite adducts as retanning agents. In particular, retannage with the bisulfite adduct of tolylene diisocyanate greatly improved the fullness, resilience, flexibility, break, color, thermal stability, and enzymic resistance of chrome-tanned leather, with minimal effects on other desirable properties. |