Don Rosato

Keyword Abstract: bioplastics, electronics, UL, Underwriters Laboratories, flame retardance, metal hydroxide, polylactic acid, PLA, heat resistance, bending strength, kenaf, fiber, DTUL, Deflection Temperature under Load, computer case, NEC, Unitika Textiles

Flame Resistant PLA Resin

NEC Corporation has developed a flame resistant biodegradable PLA resin rated at UL94 5V and UL94 V-0/1.6mm test piece thickness, without the use of toxic halogen or phosphorous type flame retardants. A special metal hydroxide flame retardant that absorbs heat during ignition is added.

This bioplastic satisfies top-level flame resistance standards regulated by the Underwriters Laboratories (UL), which will enable it to be widely used in electronic products. Personal computers and TVs require standards higher than V-1, while other electronic products that generate heat at high temperature, such as projectors, require a UL rating of 5V. By combining special additives, it also boasts other important characteristics such as heat resistance, moldability, and strength that are comparable to those of fiber-reinforced polycarbonate used in desktop-type electronic products. NEC will apply the flame resistant bioplastic to the housing materials of electronic products.

Flame-Retarding Effect of Specific Metal Hydroxide on PLA [Source: NEC Corporation]

High Strength and Heat Resistant bioplastics

NEC Corporation, one of the world's leading providers of broadband and mobile internet solutions, has successfully developed a bioplastic with substantially higher heat resistance and strength (rigidity) than conventional bioplastics composed of polylactic acid (PLA). This bioplastic that features a thermal deformation temperature 1.8 times higher and strength (bending modulus) 1.7 times higher than conventional PLAs was achieved by reinforcing polylactic acid with kenaf fiber (plant within the cotton family).

The superior heat resistance and strength of this bioplastic allows use in high-end applications such as electronic devices. This NEC developed bioplastic has the following attributes:

DTUL (Deflection Temperature under Load) of PLA/Kenaf at Various Kenaf Fiber Loadings [Source:NEC Corp.]

bioplastics composed of organic materials such as polylactic acid are of interest as eco-friendly plastics that effectively utilize reproducible biomass materials. However, bioplastics developed until now have been difficult to use in electronic devices due to inadequacies such as low thermal deformation tolerance and brittleness.

Kenaf grows quickly and has the highest CO₂ absorption capacity of any plant, thereby helping to prevent global warming. Most commonly used as a substitute for materials such as paper fiber and animal feed, this new development will broaden the application range of kenaf into previously unexplored fields such as electronic devices. The kenaf fiber used by NEC was supplied by Nature Trust Inc., the first company to successfully grow kenaf in bulk (in Australia). NEC has commercialized the use of PLA/kenaf composite for personal computer parts.

NEC Biodegradable Computer Case Commercialized

PLA/Kenaf Biodegradable SD Dummy Card and Laptop Base [Source:NEC Corporation]

NEC Corporation has commercialized a biodegradable plastic composite that is suitable for personal computer case applications. The composite material is made from polylactic acid with fibers of the kenaf plant, an herbaceous annual related to cotton, incorporated to provide both increased strength and heat resistance. The material's heat resistance, processability, and strength are comparable to that of fiber-reinforced polycarbonate. It can withstand temperatures up to 120°C before it begins to deform, which is 80% higher than normal polylactic acid. The material is also 70% stronger in terms of its ability to withstand bending forces. NEC plans to use the plastic in cases for its laptop computers and aims to have 10% of their line of laptops biodegradable by 2010. NEC is using commercial PLA sourced from several producers. The company has secured a source of kenaf fibers from Australia and is working to lower the manufacturing cost of the compounded plastic. Together with textile manufacturer Unitika Textiles Ltd (a subsidiary of major textile producer Unitika Ltd,) NEC initiated commercial use of the biodegradable plastic composite with NEC using the PLA/kenaf composite in the parts of its personal computers such as the SD dummy card.