Dried Urushi Lacquer Film Comprizing Several New Types of Inorganic Linkage and Urushiol Matrix

" This paper concerns the hardening mechanism of urushi lacquer.The author wished to propose an entirely new mechanism for the room-temperature hardening of urushiol in this natural resin.Aninvestigation of the unit reactions correlated to the mechanism indicated that the catechol moiety of urushiol and metalhydroxides play an important role in hardening.According to the results,the structure of one component of urushiol as・acetone powder”,odtained from raw urushi sap,was clearly determined.On this basis,it is disclosed that the polymerization of urushiol does not depend on the opening of the sesquiterpene double bond,but is mainly associated with a new type of inorganic ionomer bonding,such as silanolate and carbohydroperoxide-calcium hyroxide,-magnesium hydroxide or -oter metal hydroxide combinations' hydrogen bonding bridges with the urushiol matrix."