Bioplastics for Electronic Equipment

Tackling the development of biomass-based plastics -(Bioplastics) for electronic equipment-

Kenaf fiber-reinforced polylactic acid

To enable polylactic acid to be used for the casing of electronic equipment it is necessary to greatly improve its heat resistance, strength, and formability. We therefore worked to improve these characteristics by combining biomass-based additives such as kenaf fiber. As a result we developed a new composite material: kenaf fiber-reinforced polylactic acid. (See Fig. 2.) This material boasts the highest biomass-based content (90% of resin content, excluding inorganics) of any bioplastic for electronic equipment. --> June 14, 2005 press release in Japanese

Kenaf is a plant originally grown in Africa, with one of the highest rates of CO2 absorption of any plant. (Its photosynthesis rate is 3 to 9 times higher than ordinary plants resins, and it is capable of absorbing approx. 1.4 tons of CO2 per ton of kenaf.) It is thus a very effective plant in terms of global warming prevention. It is now being cultivated in Southeast Asia and many other countries around the world, mainly as a substitute for existing materials for uses such as paper fiber and livestock feed. No high added-value uses of the plant had been developed before now.

The results of tests conducted by adding and kneading in kenaf fiber with polylactic acid to enhance stiffness show that the addition of 15% or more of the fiber results in better heat-resistance (deflection temperature under load) and modulus than that of petroleum-based ABS resins. (See Fig. 3.) This effect was found to result not only from the fact that kenaf fiber inhibits the deformation of resin, but also by its ability to promote crystallization of polylactic acid. We also found that the removal of kenaf particles and the addition of plant-derived agents to promote ductility resulted in improved impact strength. Furthermore, by combing kenaf fiber with a new crystallization promoter, it is possible to cut molding time from more than five minutes down to less than one minute. We were thus successful in dramatically improving moldability.

This kenaf fiber-reinforced polylactic acid was commercialized jointly with Unitika Ltd. in September 2004, when the material was used to make the dummy card for a personal computer. Then in March 2006 the material was adopted for the casing of an "eco" mobile phone. (See Fig. 4, and March 20, 2006 press release.) This was the first mobile phone in the world with a casing made mostly of bioplastic. The phone was designed to take advantage of the unique quality of this bioplastic material, i.e., color tones to evoke a gentle, soothing feeling, and the lack of a thick coating, to allow the special touch of the material to be felt. The product made a significant impact!

Top of this page