New cellulose-based bioplastics have been developed which realize elegant black (Urushi black) of traditional Japanese lacquerware. In order to apply bioplastics to various durable products, a new additional value, “decorativeness” was aimed at, in addition to environmental friendliness and durability. Although “Urushi black” of high-grade lacquerware is highly regarded internationally, mass production of the lacquerware is difficult. The new bioplastics, in contrast, can be mass-produced into products of various shapes using the molding process for ordinary plastics.<br/>The development process involved, first, fabrication of a high-grade Urushi craft model (lacquerware model) by a top-level lacquerware artist. The model was found to show an extremely low brightness (about 1) and an exceedingly high glossiness (about 100). Aiming at the optical characteristics of the model, bioplastic composites were produced by mixing a short-side-chain cellulose resin (cellulose acetate propionate) and specific additives, and were molded by injection molding using mirror-finished metal molds.<br/>Low brightness was found to be achieved by specific surface-treated carbon particles. High glossiness was realized by adding particular high-refractive-index aromatic organic compounds. Although there is usually a trade-off relationship between low brightness and high glossiness, optimization of the surface structures of the carbon particles and molecular structures of the aromatic organic compounds lead to resolution of the trade-off. The bioplastic composites realized low brightness and high glossiness close to the model, and furthermore, “depth” and “warmth”, which are unique to high-grade Japanese lacquerware.

Development of cellulose-based bioplastic featuring high optical characteristics of traditional Japanese lacquerware: Urushi black bioplastic

253rd National Meeting (2017)

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