Лако-красочные материалы — производство

Another application of condensed tannin extracts that has proved technically successful is as tire cord adhesives. Both thermosetting tannin formulations [68] and tannin-resorcinol — formaldehyde formulations have been experimented with successfully.

A. New Concepts and Principles

1. Surface Catalysis

As in the case of other formaldehyde-based resins the interaction energies of tannins with cellulose obtained by molecular mechanics calculations [43] tend to confirm the effect of surface catalysis induced by cellulose on the curing and hardening reaction of tannin adhesives. The considerable energies of interactions obtained can effectively explain the weakening of the heterocyclic ether bond leading to accelerated and easier opening of the pyran ring in a flavonoid unit, as well as the facility with which hardening by auto­condensation can occur. As in synthetic formaldehyde-based resins the same effect explains the decrease in energy of activation of the condensation of polyflavonoids with formaldehyde leading to exterior wood adhesives curing and hardening [69].