Materials New biobased
Materials New biobased plastic for technical applications Ratio of Plant-based content High Moldability By Masaya Ikuno Design for Environment Group Fuji Xerox CO. Kanagawa; Japan Conventional ABS plastic The former plastic The new plastic The new plastic The former plastic ABS plastic HB V-2 V-1 V-0 5V Flame retardance level (UL94) Alloy PLA plastics in the market Fig. 1: The new bio-based plastic’s position in the Japanese market of flame-retardant polylactic-acid-based plastics. Ratio of plant-based content 5 4 3 2 1 0 Impact resistance 1. Introduction As the issue of climate change was discussed as one of the main agendas in the G8 summit and in the United Nations Framework Convention on Climate Change, the subject is now attracting attention around the world. Under these circumstances, the Japanese government promotes the use of the renewable resource ‘biomass’ through the ‘Biotechnology Strategic Scheme’ and the ‘Biomass Nippon Strategy’ policies. This is because the government focuses on the ‘carbon neutrality’ of biomass to prevent climate change and also aims to reduce the use of fossil resources by using biomass as a renewable resource. In response to the above two policies, the size of the Japanese market for biobased plastic is expanding gradually, although the speed is still far slower than expected by the government. In 2007, to be more environmentally friendly, Fuji Xerox developed a plantbased plastic (hereinafter referred to as former plastic) that represented an alternative to petroleum-based flame-retardant acrylonitrile butadiene styrene (ABS). This plastic was introduced for movable sections inside multifunctional machines and printers. Parts made of the former plastic were the first to acquire the Japanese BiomassPla logo (BP logo see Fig. 3) for multifunctional machines and printers. A BP logo is a certification provided to plastic products with a plant-based content of more than 25 percent by weight by the Japan BioPlastics Association (JBPA) (see bM 02/02008). After that, this plant-based plastic has been progressively introduced for parts in new Fuji Xerox products. The former plastic, however, was a material with a biomass ratio (by weight) that is comparatively low for biobased materials because it consisted of a polymer alloy of polylactic-acid (PLA) and a ‘petroleumbased resin blend’. In recent years, to have customers use multifunctional machines and printers more safely, high flame retardancy (according to UL 94) has been required for some plastic parts. Flame retardancy of the former plastic was not high enough (rated V-2) to be introduced for such parts. Therefore, with a strong design concept to develop a high plant-content plastic without using rapidly depleting resources but by fully utilizing the experiences in developing the former plastic, Fuji Xerox succeeded in establishing the new formulation of biobased plastic that has a high plantbased content and high flame retardancy, and succeeded in introducing the plastic for use in movable sections inside multifunctional machines and printers. Flame retardance Flexibility 2. Characteristics of the new plastic Heat resistance Fig. 2: Comparison of characteristics between Fuji Xerox’s new biomass plastic, the former biomass plastic, and conventional ABS plastic Fig. 1 shows the position of the new plastic in the Japanese market. The main characteristics of this plastic are a biobased content of approximately 60 % and flame retardancy rated V-1 (UL 94). Since the biobased content is comparably high, the new plastic was the first in the multifunctional machine and printer industry to acquire the BiomassPla 50 logo, which is provided to plastic products with a plant-based content of more than 50% by wt. by the JBPA. 24 bioplastics MAGAZINE [01/12] Vol. 7
Materials Fig. 2 shows the comparison between the characteristics of the new plastic with those of the former plastic and those of Fuji Xerox’s conventional flame-retardant ABS plastic. Although the new plastic holds the advantage in terms of biobased content and flame retardancy, some of its properties are inferior to those of the former plastic and those of the conventional ABS plastic. Collaboration between the material development department and the engineering design department led to an improved material so that it can now be used for those movable sections in multifunctional machines and printers. Fig. 3 shows the Drum Cover, which is one of the parts for which the new plastic is being used. Since it is a movable section, the evaluation must reflect its actual usage. The static and dynamic loads applied to this movable section, which is opened and closed for cleaning or replacement of parts by customers or service engineers, were closely examined. For example, it was predicted how often the part will be opened and closed, and opening and closing tests for several hundreds of times were conducted. By repeating such tests reflecting the actual usage of each part, it could be confirmed that there are no issues in practical use and Fuji Xerox was confident to introduce the new biobased plastic to products. 3. Technology Summary of the New Plastic As is shown in Fig. 1, many of the PLA based materials in the market consist of polymer alloys of PLA and petroleum-based resins. This is because it is difficult to ensure flame retardancy and strength for plastics which only use plant-based resins (PLA) as its base constituent, compared to polymer alloys. Fuji Xerox overcame this issue by selecting effective phosphorous flame retardants and combining the flame retardants to achieve higher retardancy (rated V-1, UL 94) in the new plastic based on polylactic acid resin compared to that in the former plastic. To achieve high flame retardancy, it is necessary to include higher amounts of flame retardants, which generally have a negative impact on some of the properties of the plastic. Therefore, it was essential to develop a material that delivers high flame retardancy and still maintains the characteristics required for the plastic parts. Actually, a material based on the combination of only PLA and flame retardants would result in a plastic material with insufficient properties and it would be impossible to be used in a multifunctional machine. To ensure the strength of the plastic, the additives to increase the adhesion between the base resin and additives (Fig. 4) were optimized, as well as the molecular weight and cross-linkage of the base resin to create a material that is highly resistant to impact (Fig. 5 and Fig. 6). By introducing this technology, eventually a plastic of high biobased content and high flame-retardancy was introduced for movable sections. Additive Before adding the new additive Fig. 3: Drum cover of Fuji Xerox copy machine Additive After adding the new additive Fig. 4: Comparison of adhesion of additives and base resin in plastic before and after adding the new additives High Flexibility Elongation at break % Five Five times times higher Low Before adding the new additives After adding the new additives Fig. 5: Comparison of flexibility before and after adding the new additives bioplastics MAGAZINE [01/12] Vol. 7 25
