NTT DoCoMo Adopts New Material in 3G FOMA Mobile

ASIA Japan : NEC Corporation (NEC) and UNITIKA announced the joint development of bioplastic reinforced with kenaf* fiber, which is expected to contribute greatly to environmental measures for mobile phones. NTT DoCoMo, Inc. (NTT DoCoMo) is already using this new material in the entire casing of its new FOMA(TM) "N701iECO" mobile phone, which it launched on the Japanese market on March 10, 2006.

Biomass-based bioplastics, such as polylactic acid (PLA)** that is made of corn, have been drawing attention in recent years as new materials to replace conventional petroleum-based plastics, amid increasing interest and concern over environmental problems such as global warming and resource depletion. However, application of regular PLA to electronic devices is difficult as it has insufficient heat resistance and strength.

NEC succeeded in improving the heat resistance and strength of PLA by adding kenaf fiber to it, one measure for the prevention of global warming. Then together with UNITIKA it realized the durability of the new material by applying it to the components of a PC. More recent research carried out by both companies involved the further improvement of the characteristics of the kenaf fiber-reinforced PLA in order to allow its application to mobile phones. Its moisture resistance was improved by UNITIKA, using their commecialized PLA "TERRAMAC." Fall impact*** durability was increased by adding a biomass-based flexibilizer and a reinforcing filler that NEC developed for this resin. In addition, moldability was further advanced by using original additives that were jointly developed by NEC and UNITIKA.

The newly developed bioplastic achieves the highest biomass ingredient ratio out of all bioplastics that are currently being used in electronic devices, with a ratio of approximately 90%. It simultaneously realizes a high level of fall impact durability, moldability and heat resistance****, which are all desired features for mobile phone casing.

Features of the New Bioplastic

Heat resistance was dramatically improved by adding kenaf fiber as a reinforcing agent to the polylactic acid, a typical bioplastic material. In addition, by adding a biomass-based flexibilizer and reinforcing filler, which have special compositions, the fall impact durability and strength characteristics have been improved.
Through a composition that is based on special biomass material including kenaf, other biomass-based additives and PLA, a high biomass ingredient ratio of approximately 90%, the highest in the range of bioplastics for electronic devices, has been achieved.
NEC and UNITIKA will continue to positively advance application of the bioplastic to electronic devices toward the further reduction of environmental load.

* Kenaf has a considerably fast growing speed (usually growing at a speed of three to 9 times that of the average plant), and has a preeminent carbon fixation effect (1.5t of CO2 in the air is absorbed per 1t of kenaf). Although conventional uses include material for paper and feed etc., an effective use for kenaf has not been discovered to date.

** This is plastic in which polymerization of the lactic acid is achieved through fermentation of materials such as corn. It is already in mass production. Presently the biomass-based plastic has insufficient heat resistance and strength for use in electronic devices.

*** A method to evaluate the damage to an object, such as a cell phone, when it is dropped from a predetermined height.

**** Evaluation by applying heat until an object changes its form while load is being applied. By adding kenaf fiber, the temperature at which PLA changes form can be improved by over 20 degrees Celsius.

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