Development of highly reactive hardening agents for MP tapes

Abstract The reactivity of isocyanate groups was examined using molecular orbital calculations and magnetochemical measurements. We found a linear relationship between the logarithm of kinetic constants for the addition reaction of the phenylisocyanates with 2-ethylhexanol and the atomic charges of the carbon atoms in the isocyanate group. A linear relationship was also found between the kinetic constants and the 13 C chemical shifts of the same carbon. On the basis of these relationships, a new hardening agent consisting of Cl-substituted phenyldiisocyanates (CPDI) was synthesized. The degree of cross-linking of the binder film was improved by using the new highly reactive hardening agent. Furthermore, the loss of signal amplitude of MP tape using the new agent was less than that using the conventional agent in pause mode test.