The Relationship between the Change of Progress Time in the Urushi Liquid by the Enzymic Polymerization and the Natural Drying Property Occurring under a Low Humidity Environment

Kisuke NAGASE, Yukio KAMIYA, Toru KIMURA, Kengo HOZUMI and Tetsuo MIYAKOSHI*

Department of Industrial Chemistry, School of Science and Technology, Meiji University; 1-1-1 Higashi-Mita, Tama-ku, Kawasaki-shi 214-8571 Japan

We conducted a basic experiment for the purpose of developing polymerized urushi that has a natural drying property in a low humidity environment, and examined the hardening process of the coating film with time as the urushi liquid dried by the enzymic oxidization using laccase in a constant temperature and humidity chamber (URUSHI MURO).
We postulated that the auto-oxidation of the side chain easily occurs in the urushi liquid due to the enzymic polymerization based on the change in the infrared absorption spectra during the drying process and anti-oxidation property of raw and sugurome urushi.
And, as a result, the change in the progress time of the drying property and degree of polymerization of the urushi coating film and liquid thin phase were measured. The molecular weight distribution of the urushiol in the time that naturally dries in a low humidity environment was admitted that the monomer component decreased to 27% or less.
From that it was found out possibility that the polymerized urushi that naturally dries in a low humidity environment can be obtained by stirring with additional moisture raw urushi in the reaction vessel of shallow bottom and decreasing urushiol monomer.

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