Japanese lacquer films

Japanese Lacquer Films Lacquers are used ubiquitously as surface-coating materials for wood, porcelain, and metal. The main component of Japanese lacquer ( ura-shi in Japanese) is urashiol, a brown liquid (boiling point, 200-210 °C) consisting of a mixture of several catechols, each substituted with a satmated or unsaturated alkyl chain of 15 or 17 carbon atoms [55]. The liquid that causes an allergic skin reaction in most people, is obtained from the sap of the Japanese lacquer tree (Rhus vemicifera) and can be polymerized to form lacquer films. Lacquer films have been... 

Fig. 6.7 A typical Li ion attachment mass spectrum of the products from the pyrolysis of a Japanese lacquer film recorded as the furnace temperature increased from 50-500 °C. Samples were placed in the EGA furnace and heated linearly in a atmosphere at a programmed rate of 128°C/min. The relative intensity is given as a percentage of the intensity of the carboxylic acid peak at m/z 81 (C HjCOOHLi ). Inset a partial mass spectrum from m/z 315 - 345. These peak clusters correspond to the urushiol monomer. (Reprinted with permission from Ref. [64]. 2012, Elsevier)...

This proved to be the first scientific data evidencing the high durability of the Japanese lacquer films, though obviously the 20 years span in this case is very short to make a comparison with an unchanging record of 1,000 years. 

Fig. 5. IR Spectra for the plant gum separated from a sap of lacquer trees (Rhus vernicifera), a Japanese lacquer film J(L, 17Y) and sap films J(S, IM) and J(S, 17Y).

Considering these findings we here propose a cell structure for the durable Japanese lacquer film the lacquer film is composed of cells or grains of 0.1 ym size packed densely in the film. The cells have plant gum wall with polymerized urushiol inside, and are firmly... 

Fig. 13. A scanning electron microphotograph for an etched Japanese lacquer film aged for 18 years.

In this cell structure model, the plant gum provides a protective barrier towards diffusion of oxygen into the polymerized urushiol inside, resulting in and explaining the high durability of Japanese lacquer films. Since the plant gum is hygroscopic, absorption of humidity would break down the barrier characteristics, and thereby causes degradation of the polymerized urushiol in the lacquer film, but a combination with hydrohobic polymerized urushiol results in a cell structure wall of low humidity absorption. 

In order to elucidate the formation of aggregated cell structure made from plant gum and urushiol in Japanese lacquer films proposed above, it is most important to know the interaction between urushiol and plant gum in the sap being treated or in the lacquer in the film formation process. 

In addition, MMA-grafted pullulan (a water soluble polysaccharide, M, 100,000) was prepared by using ceric ammonium nitrate as initi-ater in an aqueous medium35. A scanning electron microphotograph of the film made from a butyl acetate-acetone solution showed an aggregated cell structure in the film like in Japanese lacquer films as shown in Fig. 18. 

Raw lacquer is called urushi. For our knowledge of the composition of urushi and the complex hardening process of the thin film layers, we now rely primarily on the recent work of Kumanotani and his coworkers (1-7). The sap of the Japanese lacquer tree is a latex containing 20-25% water, 65-70% urushic acid (urushiol), approximately 10% gummy sub-... 

Rhus vernicifera n. C22H31O3. Chinese tree which delivers a milky type of liquid. When the water is removed, a dark oily liquid is obtained, which yields a tough flexible film on atmospheric oxidation. The chief constituent of the film-forming material is an unsaturated phenol-acid-urushiol. The liquid is used for the preparation of Japanese lacquer. 

Naturally drying oils, including dammar, Japanese lacquer and shellac, are suitable for lacquers and varnishes because they dry quickly, although the film... 

Tsukagoshi M, Kitahara Y, Takahashi S, Tsugoshi T, Fujii T. Charaeterization of Japanese lacquer liquid and films by means of evolved gas analysis-ion attachment mass speetrometry. Anal Methods. 2011 3 1943-7. 

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