NEC Corporation has developed a completely new kind of
bioplastic composed of plant-based material and carbon fiber, which
realizes heat conductivity higher than that of stainless steel. The
innovative bioplastic is expected to make electronic products more
environmentally sound, while solving conventional heat release
issues.
The features of the new bioplastic are as follows:
1) Creation of a cross-linked structure of carbon fiber through use
of a unique binder in the polylactic acid (PLA)*1 resin achieves
high heat diffusion (with carbon fiber of 10% and 30% the heat
diffusion ability of the new bioplastic composite is comparable to
and double that of stainless steel respectively). This enables good
heat conductivity in the plane direction of the PLA resin board,
which is a characteristic conventionally difficult to attain in
metal boards.
2) The composite is extremely environmentally friendly as it is
mainly composed of biomass-based components including the binder
(the biomass ratio exceeds 90%, excluding inorganic components such
as the carbon fiber).
3) The strength and moldability of the composite have been
fundamentally verified for use in electronic products.
NEC’s newly developed bioplastic composite in the housings of
electronic products easily releases the heat generated from
electronic parts with high temperatures through whole housing
surfaces, while slowing up an increase in the temperature of the
housings near parts.
Recently, small-sized electronic products such as mobile phones
and personal computers have suffered heat-release issues due to an
increase in the amount of heat being generated from electronic
parts. However, conventional heat-release devices such as fans and
sheets are difficult to incorporate as products become smaller and
slimmer.
In electronic product housings, the use of heat-conductive
metals is considered to be one alternative to plastic for improving
heat release, however, heat conductivities in the thickness
direction of metal boards are too high and can cause partial or
rapid increase in the temperatures of housings near electronic
parts that have high temperatures, causing unnecessary anxiety to
the user.
Attempts have been made to increase heat release from whole
parts of housings by using heat-conductive plastics. However,
previous heat-conductive plastics have had the disadvantages of low
moldability, as well as high densities and costs, as they contain
large amounts (more than 50%) of heat-conductive fillers such as
fibers or particles made from carbon and metals. Therefore, a
new kind of heat-conductive material has been long sought after to
solve these issues.
On the other hand, however, recent bioplastics made from
renewable plant resources, including PLA, have been enjoying
increasing attention as new environmentally friendly materials and
are now starting to be used in electronic products. But, PLA has
low heat conductivity like current petroleum-based plastics and
many of its practical characteristics are also lower than those of
petroleum-based plastics.
NEC has been focusing its research activities on how to solve
these bioplastic issues and has succeeded in the development of a
kenaf*2 fiber- reinforced PLA composite that realizes high heat
resistance and strength. Moreover, the composite is already
being used in a mobile phone commercialized by NEC. In
addition, NEC has also discovered how to add flame retardancy -
without using toxic flame retardants - and shape memory to PLA.
The new bioplastic that achieves high heat conductivity has been
enabled by new technology for carbon-fiber cross-linking with a
unique biomass-based binder, which were both realized at NEC’s
fundamental and environmental research laboratories.
NEC will continue to develop these technologies toward
realization of mass production of the bioplastic composite by the
end of the fiscal year ending March, 2009, after which it will
start to use the composite in housings of electronic products and
seek out new applications.
Notes
1: Polylactic acid bioplastic
A plastic now being mass produced that consists of polymerized
lactic acid made from fermented corn etc. Although this
plastic has the best heat resistance and strength features of all
mass-produced organic plastics, its characteristics have been
inadequate for use in electronic equipment.
2: Kenaf
Kenaf grows faster than any other plant (3 to 9 times faster) and
is extremely effective in absorbing carbon dioxide gas (one ton of
kenaf absorbs 1.5 tons of atmospheric CO2). However, kenaf
has traditionally been used as a substitute for existing materials
such as paper fiber and animal feed, and
its potential has been unexploited in the past.
About NEC Corporation
-------------------------------
NEC Corporation (NASDAQ: NIPNY) is one of the world's leading
providers of Internet, broadband network and enterprise business
solutions dedicated to meeting the specialized needs of its diverse
and global base of customers. NEC delivers tailored solutions in
the key fields of computer, networking and electron devices, by
integrating its technical strengths in IT and Networks, and by
providing advanced semiconductor solutions through NEC Electronics
Corporation. For additional information, please visit the NEC home
page at: http://www.nec.com