Committed to reducing environmental impact using bioplastics that have new possibilitiesMitsubishi Chemical Corporation
Paper cup manufactured from BioPBS with excellent biodegradability
- Engaged in research with 2 objectives, develop alternatives for products manufactured from petroleum resources and the creation of new added value
- Development of 2 types of bioplastics with different functionalities
- Aim for entering the Japanese market, while responding to the demand in Europe
The problem of marine pollution caused by microplastics has gained attention in recent times. Also, the risk of petroleum resources getting exhausted has been pointed out from before.
From as early as the eighties, Mitsubishi Chemical Corporation has been engaged in the research and development of new products that are environmentally friendly, assuming a future where petroleum resources will be scarce.
The company tries to solve such problems by concentrating all efforts of the group particularly into the research and development of bioplastics, the writer spoke to Mr. Masahiro Urushisaka, Group Manager, Planning and Management, Sustainable Resources Headquarters, High Functional Polymers Division.
They are engaged in research on bioplastics keeping 2 concepts in mind.
The first concept is to reduce the consumption of petroleum resources. For example, they are substituting raw materials derived from petroleum resources little by little with plant-derived raw materials and increasing the ratio of plant-derived materials in the raw materials to develop alternatives for products produced using petroleum resources.
The other is advanced biotechnology research to create products with high functionality that cannot be manufactured using conventional petrochemicals. Instead of just developing simple alternative materials, they manufacture unique products, which were not available up to now, creating an entirely new value addition.
Biodegradability and ratio of renewable raw materials are the 2 factors of bioplastics
To begin with, the definition of “Bioplastics” includes 2 factors. The first is “Biodegradable plastic” that is returned to nature by the activity of microorganisms, and the other is “Biomass plastic” that is produced from renewable raw materials such as plants. There is no correlation between the 2 indices, “Biodegradable” and “Ratio of renewable raw materials”, some materials are highly biodegradable even if the raw materials used are from petroleum, and some are non-degradable though plant-derived raw materials have been used.
The figure below is a 4-quadrant matrix where the horizontal axis is “Biodegradability” and the vertical axis is “Ratio of renewable raw materials”, biodegradability increases as you go along the horizontal axis and the ratio of renewable raw materials increases as you go along the vertical axis.
As mentioned above, bioplastics are materials that are “Biodegradable or manufactured using renewable raw materials”. In the above figure, materials that are in quadrants other than the fourth quadrant (Quadrant in pink) are called bioplastics.
The company has succeeded in developing 2 types of bioplastics with different properties from plant-derived materials called “DURABIO” and “BioPBS”, and is promoting sales and marketing by utilizing their respective functionalities.
“DURABIO” with new added value
“DURABIO” is one of the bioplastics developed by the company that is a non-degradable, plant-derived polycarbonate resin having a glass-like gloss not found in conventional polycarbonates, with excellent durability and weather resistance. They discovered that isosorbide could be easily refined from plant-derived materials instead of producing it from petroleum resources, and commercialized the material.
Though DURABIO was expected to be used in Flat Panel Display (FPD), which is a substitute for television screen glass, it was extensively used in automobile interiors as the material was highly scratch resistant. The material is also used for soundproofing the walls of expressways, utilizing the feature that it is less likely to deteriorate because of its excellent weather resistance.
Although the cost of bioplastics is high compared to conventional plastics, DURABIO has a good surface finish after molding and can be commercialized without painting, this reduces the number of processes, and the overall cost is almost the same.
BioPBS is biodegradable even at normal temperatures or in the ocean
BioPBS is also a bioplastic developed by the company with biodegradability that is higher than biodegradable plastics. BioPBS was initially produced from petroleum resources with succinic acid and 1,4-Butanediol as raw materials, later succinic acid was changed to a plant-derived material, and commercial production started in May 2017. The annual production capacity in 2018 was 20,000 tons at a joint-venture factory with PTT Public Company Limited.
One notable feature of BioPBS is that it degrades at normal temperatures. Typical bioplastics decompose efficiently in industrial composts operating at 60°C, but degradation is extremely difficult at normal temperatures, where the activity of microorganisms is suppressed. BioPBS solves this problem and is properly decomposed even in composts at home without using heating systems, and a broader range of application is expected compared to conventional plastics.
It is also confirmed to have marine biodegradability. The ocean is a harsh environment for biodegradable plastics because of low temperatures and fewer microorganisms that promote decomposition. For this reason, microplastics in the ocean have become a problem, and BioPBS can solve this problem.
The company plans to change the raw material 1,4-Butanediol to a plant-derived material in the future. The technology has already been established, and they are currently performing tests for mass production. A 100% plant-derived BioPBS is expected to be introduced soon.
Applications of bioplastics are extensive
For example, a typical application of BioPBS is in mulch films used for agricultural. The film is used to cover ridges for retaining moisture and heat, and to suppress weed growth. Polyethylene films were used before, but retrieving mulch films after harvesting the crops was labor-intensive, and disposal was expensive. Films made of biodegradable BioPBS will decompose and return to the ground by plowing together with the soil.
Coffee capsules are used in the food industry. Products manufactured from conventional plastics are difficult to recycle as it requires effort for cleaning. However, if BioPBS is used, the products will decompose just by dropping in the compost, this allows circulation of resources.
BioPBS has excellent heat and impact resistance and can be molded using various processing methods, and it is also used in disposable tableware and cutlery such as spoons and forks. Though the global interest on plastic debris found in the ocean is increasing, small items slip through the recycling process and turn into marine waste, and this has drawn attention to biodegradable bioplastics.
Impact of restrictions by China on plastic waste imports
There is another reason as to why the increasing interest in bioplastics cannot be overlooked.
Up to now, most of the plastic waste was exported to China. However, China prohibited the import of plastic waste at the end of 2017. Although such plastic waste can still be exported to other countries such as Malaysia, Vietnam, and India, the transaction costs of exports are increasing. In Europe, there is an increase in the number of people who are thinking “If disposal costs are high, it would be better to use biodegradable plastics, even if it is comparatively expensive”.
Aim for the popularization of bioplastics in response to the growing concern
In addition to legal regulations in Europe, big companies such as Starbucks, Unilever, and McDonald’s are actively promoting the phasing-out and reduction of disposable plastics and introducing bioplastics. In particular, many businesses are declaring that they will stop the use of plastic straws, and companies with similar intentions are also increasing in Japan.
The company is promoting the introduction of straws made with BioPBS as an alternative product. Besides, they are also cooperating with efforts to coat paper straws with BioPBS. Mr. Urushisaka said, “We want to cooperate for the development of biodegradable materials such as paper and bioplastics with other companies to complement each other's features and manufacture better bioplastic products”.
Mr. Urushisaka further added “The recent increase in discussions on plastics is certainly a business opportunity for the bioplastics business. From here on, it is also expected to spread in Japan”.
The company will promote the replacement of materials for products that are difficult to recycle such as films used for packaging food that tend to leave food residue and non-woven fabric products such as towels, with highly biodegradable plant-derived polymers.
Interview Date: November 20, 2018
Mitsubishi Chemical Corporation
The 3 companies, Mitsubishi Chemical Corporation, Mitsubishi Plastics, Inc., and Mitsubishi Rayon Co., Ltd., were merged in April 2017 to establish an integrated chemical manufacturer having a wide range of products and markets. One of the main divisions is the plastics-related business called the High Functional Polymers Division, which is engaged in the research and development of biopolymers from the eighties. Given the recent interest in microplastics, they are also promoting the market expansion for bioplastics in Japan.
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