Development of Novel Crosslinking System Based on Equilibrium Reaction of Thermal Dissociation of Hemiacetal Ester

Masahiro ISHIDOYA*†, Yoshinori NAKANE, Kishio SHIBATOH, Osamu OHE and Takeshi ENDO††

NOF Corporation Coatings Research Laboratory; 296, Shimokurata-cho, Totsuka-ku, Yokohama-shi 244-0815 Japan
Present address: NOF Corporation Organic Chemicals Division; 4-20-3, Ebisu, Shibuya-ku, Tokyo 150-6019 Japan
†† Present address: Department of Polymer Science and Technology Faculty of Engineering, Yamagata University; 4-3-16 Jonan, Yonezawa-shi@992-8510 Japan

Novel thermal latent hardeners containing blocked carboxyl groups with alkyl vinyl ethers i.e. hemiacetal esters, have been developed. They showed liquid form or lower melting point and excellent solubility and compatibility. Although the blocked carboxyl groups were stable under usual condition, they could regenerate the corresponding free carboxyl groups by thermal dissociation of hemiacetal ester. A novel crosslinking system between blocked carboxyl group and epoxide was examined. The new one-package thermosetting coatings provided by the system have been applied to practical automotive and coil coatings line production. The formed coatings have high level of acid resistance, corrosion resistance and weatherability with reduction of VOCs.

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