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Please
give an overview of your company’s experience of carbon fiber development. |
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Carbon fiber was an innovative technology
for Mitsubishi Chemical Functional Products, and is now also an area of innovation
for Mitsubishi Plastics following the integration this spring. The achievements
in this area reflect seven decades of carbon chemistry experience. Our carbon
fiber business began with the development of derivatives from coal tar produced
during the manufacture of coke.
A strand
of carbon fiber is a collection of black fibers 10 times thinner than human hairs.
PAN-based carbon fibers are made from synthetic acrylic fibers, and pitch-based
carbon fibers from petroleum or coal. Japanese companies now have a 70% share
of the world markets for both types. Our DIALEAD® range of products
were the first carbon fibers in the world to be developed from coal tar pitch.
Compared with PAN-based carbon fibers, which are used in aircraft parts and other
applications that require material strength at a standard degree of stiffness,
DIALEAD® carbon fibers offer other advantages, including not only
a high degree of stiffness but also thermal conductivity and zero thermal expansion.
The last property, which means that the material does not at all expand as temperatures
increase, is particularly valuable. |
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What
challenges did Mitsubishi Chemical Functional Products face
during the development and introduction of DIALEAD®? |
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Commercial production
of DIALEAD® started in 1987, but it was not until the mid-1990s
that it began to be used in industrial applications, for instance rollers and
beams. DIALEAD® printing rollers have gained an excellent reputation
because of their rigidity, which allows them to rotate at a very high speed, and
because of their lightness, which makes them easier to maintain. They are also
highly regarded as high-performance film rollers capable of preventing wrinkling.
Mitsubishi Chemical Functional Products
came close to abandoning this business segment. However, between 1993 and 1995,
we found a new path to success in the European market. Europe is a major center
for aircraft manufacturing, and there are many companies involved in the molding
and processing of composite materials. We spent 140—150 days each year explaining
the properties of carbon fiber. A key characteristic of pitch-based carbon fiber
is its ability to resist excessive flexing. The first company to take advantage
of this was a manufacturer of fishing rods. A French satellite manufacturer was
delighted to find that our carbon fiber had a zero thermal expansion ratio. We
learned that our products could be used in ways that we had never imagined. |
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What
are some of the uses for DIALEAD® today? |
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As pitch-based carbon
fiber does not expand as temperatures increase, it was used in the construction
of the ALMA radio telescope facility in the Chilean highlands. At this high-precision
facility, researchers study the universe by combining the signals received by
an array of 80 antennae, a process called interferometry.
However,
if even one antenna was out of alignment due to temperature variations, this array
could not produce images. After studying the thermal expansion properties of various
materials, the designers eventually selected our carbon fibers.
Pitch-based
carbon fibers also have excellent vibration-damping properties and are ideal for
vibration-sensitive products, such as components for industrial robots in LCD
TV factories. The hands of the robots used to carry glass substrates must be able
to fully damp vibrations quickly. Here, DIALEAD® is helping to
reduce processing times.
DIALEAD® is also used as a reinforcing material in the construction industry. When applied
to just 8% of a cross-sectional area, strength is doubled. It was used on the
London Underground to strengthen over 400 cast-iron pillars, which had cracked
due to rusting during the 120 years since their construction. |
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What
is the future for carbon fiber? |
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| This is an area of huge
potential. Carbon fiber is expected to play a leading role in the reduction of
greenhouse gases, as it improves energy efficiency by reducing the weight of vehicles
and other machinery. Also, because it can be used to strengthen existing structures,
it reduces the need for new resources. |
Carbon
fiber is also playing a role in Europe’s expanding wind power generation
industry as the material for wind turbine blades. Some of the larger turbines
have rotor diameters exceeding 100 meters. The world’s largest, currently
under construction in Germany, has a rotor diameter of 127 meters and will be
able to generate over 6 MW of electricity. When generating capacities reach the
10 MW level, blade diameters will need to reach some 180 meters, and it will be
necessary to find solutions for the problems of vibration and distortion. Over
the next 10 years, I believe we will see many carbon fiber products contributing
to the solution of environmental problems.
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