To be suitable for use as automobile parts, plant-derived plastics (bioplastics) must have the required strength (shock impact resistance) and heat resistance.
Mazda participated in a joint research project between industry, academia and local government*1 in Hiroshima prefecture. It resulted in the creation of a bioplastic with the high strength, heat resistance and high quality finish necessary for injection-molded automobile interior parts. It is the first bioplastic in the automobile industry that maintains a high plant-derived content (over 80 percent). We altered the molecular structure of polylactic acid extracted from plants to raise its melting point and developed it as a nucleating agent. A compatibilizer compound*2 was also developed to highly disperse the shock-absorbing flexible ingredients. These two breakthroughs improved material's ability to uniformly absorb and release energy generated by impacts.
This bioplastic is three times the shock impact resistance along with 25 percent higher heat resistance when compared to contemporary bioplastics used for items such as electrical appliances.
And unlike conventional bioplastics whose properties are suitable for press-forming only, Mazda's bioplastic can be extrusion-molded. Consequently, this bioplastic can be used for various car parts.
The Premacy Hydrogen RE Hybrid featured this bioplastic in the vehicle's instrument panel and other interior fittings.
*1:This is a consortium consisting of two universities, six companies and two research institutes: Hiroshima University, Nishikawa Rubber Co., Ltd., Western Hiroshima Prefecture Industrial Research Institute, G.P.Daikyo corporation, Japan Steel Works Ltd., Kinki University School of Engineering, Nishikawa Kasei Co., Ltd, National Research Institute of Brewing, Yasuhara Chemical Co., Ltd., MANAC Incorporated and Mazda Motor Corporation.
*2:Additives are used to ensure uniform distribution of two or more materials with different chemical characteristics in order to improve the properties of the material. An Additive was needed to mix the polylactic acids with another incompatible element.
Mazda's bioplastic is a plant-derived and carbon-neutral*3 material. It reduces reliance on fossil fuels and therefore also cuts CO2 emissions. In addition, its manufacture involves fermentation of natural materials such as starches and sugars. As a result, it requires 30 percent less energy to produce than petroleum-base polypropylene plastics. The new bioplastic is also stronger than other plastics, which means parts can be thinner so less material is required for production.
*3:The same amount of CO2 that is released when the bioplastic decomposes or is burnt is absorbed by growing plants through photosynthesis. Therefore, Mazda's bioplastic has a negligible impact on total atmospheric CO2 levels.
This research was the result of a collaboration between industry, academia and the Japanese government. It was promoted under the auspices of the Japanese Ministry of Economy, Trade and Industry's (METI) “Consortium R&D Projects for Regional Revitalization” program, which began in 2004. Research conducted through this program aims to foster new industry, create new business and revitalize regional economies in Japan.
Mazda and G. P. Daikyo Corporation (now Daikyo Nishikawa Co., Ltd.) are located near the center of a world-class group of automotive plastic parts makers in the Hiroshima area. The region also has a rich tradition of sake brewing and has long been accumulating knowledge of fermentation techniques and biotechnologies. Hiroshima University, the Western Hiroshima Prefecture Industrial Research Institute (now Hiroshima Prefectural Technology Research Institute) and Nishikawa Rubber Company, among other organizations, have an extensive history of research into the practical uses of biodegradable plastics that can be broken down by microorganisms. The Hiroshima area is fertile ground in terms of research achievements.
In June 2008, Mazda signed a collaborative research agreement with Hiroshima University to launch the Mazda Bioplastic Project. The bioplastic being developed will not consume food resources because it will be made from cellulosic biomass produced from inedible vegetation such as plant waste and wood shavings. The aim is to have it ready for use in vehicles by 2013.
This project will focus on designing a production process for an extremely versatile polypropylene, appropriate for extensive use in vehicles, by first converting cellulosic biomass to ethanol and then investigating various mixtures of ethylene and propylene. The polypropylene must have sufficient heat resistance, strength and durability to be used in vehicle bumpers and instrument panels. The project also seek to optimize the manufacturing process for the bioplastic so that it is eco-friendly and cost-effective.
Japan's National Institute of Advanced Industrial Science and Technology will also participate in the bioplasitc project as part of its ongoing agreement to collaborate on biomass research with Hiroshima University.