- Efforts to achieve NEC's environmental business vision
- A world first: New technology to eliminate the need for standby power in ICT equipment
- Plastic Made from Straw and Nut Shells
- Obayashi Corporation
- A bioplastic with a biomass ratio of more than 75%
- Optimizing Power and Space with ECO CENTER
- Observing Greenhouse Gases Around the Earth from Space
- Monitoring the forests from space
- High-Performance Workplaces
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Plastic Made from Straw and Nut Shells
Unused plant resources the key to solving problems of natural resources and the environment
Cellulose, the main component of the stems of cereal grains (such as straw), grasses and wood, is a non-edible plant resource that is being regarded as a promising material for bioplastic production.
Cellulose is used often in our daily lives, from the pulp found in paper to the fiber in our clothing. The amount of cellulose produced in one year is nearly 130 billion tons. Dr. Masatoshi Iji, the bioplastics team leader at NEC Green Innovation Research Laboratories, offers the following explanation: "Cellulose is said to be the most abundantly available natural resource on earth. Yet, only 200 to 300 million tons are used per year. For example, the amount of cellulose produced as an agricultural byproduct (like straw) alone totals 2.5 billion tons and is comparable to the yearly production of petroleum."
In other words, if this natural resource is used to produce bioplastics, the environmental impact would be reduced to an extraordinary degree and the resource would be a petroleum substitute. Iji adds, "Of course, it was not only us. Researchers from around the world have focused their attention on cellulose and conceived of using it this way."
So why is it that this resource, produced so abundantly in our fields and forests, has not been used effectively until now? "Cellulose has a strong molecular structure, but it is rigid and fragile, absorbs a large amount of water, and does not melt when heated. In order to use cellulose as a material in plastics, a large amount of petroleum-based additives was needed to increase their plasticity and make them easier to melt when heated. Therefore, although they are bioplastics, such plastics have plant composition ratios of a mere 30% to 40%. In addition, even through the use of these additives, the strength, water resistance and heat resistance remain insufficient for use as a material in durable products including electronics equipment," says Iji.
To that end, since 2008 NEC has been focusing on the development of a bioplastic that uses non-edible plant materials like cellulose, possesses practical characteristics such as a high level of strength, heat resistance and water resistance, good moldability including fluidity, and achieves a high plant composition ratio.
Substituting petroleum with cashew nut shells
How can a bioplastic be produced for use in electronics equipment and maintain a high plant composition ratio using chiefly the non-edible component, cellulose? The critical key to the question was finding a plant-based resource that could be used in place of conventional petroleum-based additives, and possesses high strength, heat resistance and water resistance. NEC made a thorough, worldwide investigation of plant components that are not suitable as food. Iji looks back on that time, saying, "We inspected a variety of molecular structures in advance, and chose those that appeared to be logical fits, which we would then proceed to synthesize. We investigated roughly over 100 candidates."
The result? The sole material to meet these difficult conditions—to be non-edible, have a stable supply, and react with cellulose and improve its molecular structure—was found in that familiar snack, a unique oily material extracted from common cashew nut shells.
Cashew nuts are cultivated widely in India, Vietnam, and other countries, and approximately 1.4 million tons of non-edible shells are produced each year. Iji explains why he focused his attention on cashew nut shells, to which researchers studying cellulose-based bioplastics around the world have paid little attention. "Cashew nut shells contain an oily material called cardanol. It has a unique molecular structure that is flexible and water-repellant (hydrophobic) and contains a reactive site. The moment that I found this chemical structure, I predicted that if cardanol was bonded with cellulose, we could create a new resin of superior durability. Then, the development team made a number of attempts until we effectively bonded cardanol with cellulose. We had created a new resin that significantly outperforms the conventional cellulose resins containing petroleum-based additives." Approximately 0.4 million tons of cardanol can be extracted from 1.4 million tons of cashew nut shells. Most of these shells had not been used productively, but had been burned or otherwise discarded. Every year, 0.4 million tons of this "unique natural oil"; an oil that possesses so great an added value that it can reduce society's dependence on oil and holds the key to minimizing our impact on the environment, was not being used effectively.
New bioplastic achieves high plant ratio of over 70% and level of durability suitable for electronics equipment. A new bioplastic is born through the chemical bonding of cellulose to the natural organic material cardanol extracted from cashew nut shells. It achieves higher durability than that of conventional cellulose-based bioplastics by replacing the petroleum-based additives used in their manufacture.As stated above, cellulose, a main component of the stems of cereal grains, has a molecular structure that is rigid and absorbs water easily. It must be chemically bonded to molecules that are water-repellant and flexible to make a durable bioplastic that uses cellulose as its main ingredient and can be used in electronics. The oil molecules contained in cashew nut shells have the very structure to satisfy these criteria.
However, chemical bonding is not that easy to achieve. "The elements of our experiment—cellulose and cardanol— are not things that react readily. Development succeeded as the result of nearly 2 years of tweaking the trials, adding other materials to make cellulose and cardanol more reactive, making changes to the reacting conditions and blending them in different quantities to find an optimal composition," says Iji.
The completed product is a new material that has achieved levels of strength, heat resistance, and water resistance comparable to those of the petroleum-based ABS resin. NEC is calling it Cellulose Resin Bonded with Cardanol. Compared with the conventional cellulose-based bioplastics with a plant composition ratio of under 40%, NEC's success brings a bioplastic with high strength, resistance to heat and water and a plant composition ratio of over 70%. No other plastic has been developed that achieves such a high plant composition ratio-using for over 70% of its composition a non-edible plant resource of which there is a stable supply-with superior durability.
Commercialization of new bioplastic under the NeCycle brand
NEC is working toward the efficient mass production of this bioplastic, realizing for it a variety of uses and to have the practical characteristics for using it as a material for electronics equipment such as mobile devices and OA equipment by the end of the 2013 fiscal year. "Of course we want a business success. But more than that, everybody on my development team feels strongly about doing something useful for the world and wants to create a material that can make a major contribution to solving the problems affecting our environment," says Iji.
NEC plans to commercialize a series of original highly environmentally friendly bioplastics including this material under the NeCycle™ brand.
Dr. Masatoshi Iji Research Fellow NEC Green Innovation Research Laboratories"In the chemical modification of cellulose, what plant-based resource should we use as a substitute for petroleum-based additives...? We conducted research using fats and oils, but since those can be used for food we deemed them unsuitable. Something that cannot be used for food, that the world produces in great quantities, that is not being put to great use, and also does not contribute to deforestation. Considering these conditions, plant resources that we can use become limited. Out of those, we hit upon a part of the cashew nut shell."
NeCycle™, which is the brand name of NEC's newly developed bioplastics, indicates a new style of recycling: a recycling of the material itself as well as a recycling of the CO2 that is absorbed by the plant component that constitutes the material's main resource.
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