Plastic pollution driven by rising population will increase almost three-fold by 2060 without “radical action to curb demand, increase product lifespans and improve waste management and recyclability”.
So says the Organisation for Economic Co-operation and Development (OECD) 2022 report, Global Plastics Outlook: Policy Scenarios to 2060.
The organisation’s secretary general, Mathias Cormann, added: “If we want a world that is free of plastic pollution, in line with the ambitions of the United Nations Environment Assembly, we will need to take much more stringent and globally co-ordinated action.”
Conventional plastics, such as polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET), are very slow to degrade, so when plastic waste enters the environment, it can remain there for decades. One solution is replacing conventional plastics with those that are biodegradable, or “bioplastics”.
In the inaugural edition of Inside Green Innovation: Progress Report (2021 edition), we examined the trends in patent filings in the bioplastics sector over the last few decades. This time, we take a deeper look at patent filing trends for the main types of bioplastics produced today: butylene-based polymers, polylactic acid, polyhydroxyalkanoates and starch-based bioplastics.
Patent filings in all four types of bioplastics have risen in recent years, albeit to varying extents. For example, filing numbers for butylene-based polymers were relatively steady until about five years ago, but have experienced a notable upward trend year on year since then. Indeed, butylene-based technology stands out as the leading area of current innovation.
Similarly, although filing numbers for polyhydroxyalkanoates-related applications have been inconsistent since 2000, they have increased notably since 2015 – suggesting industry sees this as an important area for growth.
Interestingly, filings related to starch-based bioplastics have generally decreased since the beginning of the century, suggesting the technology is of lower interest. However, there appears to be renewed impetus as filing numbers have increased since 2017. It will be interesting to see if this continues.
Finally, patent filings related to polylactic acid peaked between 2006 and 2008 and, in contrast to other areas, have since declined. However, increased filing numbers in 2020 indicate a renewed interest in polylactic acids. Again, it will be interesting to see if this is an anomaly or a genuine sign that innovation in this area is on the up.
Although made from petrochemicals, butylene-based polymers – including polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS) and polybutylene succinate adipate (PBSA) – are biodegradable and have comparable properties to low-density polyethylene (LDPE) and polypropylene (PP).
Global production of butylene-based polymers is projected to increase considerably in future, likely because their properties are comparable to conventional plastics, making a transition to such materials more straightforward. For example, PBS has good clarity, processability and flexibility as well as a “shiny” appearance – properties also seen in conventional polymers. Also, it is easier to scale up production of butylene-based polymers than other bioplastics – this is likely to be key for manufacturers responding to regulatory pressure or capitalising on growing consumer demand for biodegradable products.
Global patent activity
In keeping with the general trend, most patent filings for butylene-based bioplastics during the 2000s originated in Japan (when Japan saw large numbers of patent filings relating to bioplastics generally). However, as shown in Figure 1, towards the end of the 2000s, locations for patent filings for butylene-based polymers became more evenly distributed; a trend which has continued over the past decade. Other jurisdictions experiencing significant filing activity in recent years include South Korea, the US, China, and Taiwan.
Overall, the top five filing jurisdictions saw relatively steady numbers of filings relating to butylene-based bioplastics until about 2018, which marks the beginning of a sharp upward trend (Figure 1). The significant increase in innovations relating to butylene-based bioplastics in the last few years is perhaps because of increased demand from consumers for bioplastics that have similar properties to conventional plastics in, for example, packaging.
Figure 1: Twenty-year trend: top five filing jurisdictions – butylene-based polymers
The two biggest filers of patents relating to butylene-based bioplastics over the last 10 years have been the Israel-based Tipa Corporation and the Japan-based Mitsubishi group, which suggests their sustained research and development in this field.
Tipa’s innovations relate to improvement in the properties of biodegradable packaging and single use items. Tipa appears to be focusing on blends or multiple layers of PBAT or PBS with other bioplastics, such as polylactic acid (PLA), designed to find a balance between the flexibility of the butylene-based polymers and the strength of PLA. Mitsubishi has filed patents relating to improvements in the properties of – and manufacturing processes for – PBS/PBSA polymers. For example, Mitsubishi has improved the tensile strength of PBS by blending it with an acrylic rubber. The filings indicate these companies anticipate increased consumer demand for bioplastics, particularly in packaging and other single use items.
Figure 2: Ten-year activity: top ten filers by priority filings – butylene-based polymers
Polylactic acid (PLA)
Polylactic acid (PLA) is made from sugars derived from plants. It has similar properties to polyethylene (PE), polypropylene (PP) and polystyrene (PS), but has the dual advantage of being both biodegradable and producible from natural sources. PLAs have a wide variety of applications in fields such as healthcare, medicine, packaging, and the automotive industry. It is also one of the two most used plastics in 3D printing (with a 45% market share).
Global patent activity
Again, Japan was the source of most PLA-related patent filings in the early 2000s. However, filings from Japan have declined gradually since about 2008. The number of US-originating patent filings have remained relatively constant over the past twenty years. South Korean filings picked up in 2007 and have remained mostly steady since then, apart from a notable increase from 2010 to 2012.
Overall patent filings from the top five jurisdictions have shown a steady decline since a peak in about 2008, indicating that companies have moved away from this technology. However, while numbers have now stabilised, it remains to be seen if the current level of patent filings will be sustained.
Figure 3: Twenty-year trend: top five filing jurisdictions – PLA
The biggest filers over the last 10 years in the PLA field are the LG Chemical group, Toray Industries and Unitika Corporation. Their priority filings have decreased recently, in line with the overall trend, but the LG Chemical group continues to file a significant number of priority applications. Based on its recent filing activity, the company appears to be focusing on improving the properties of PLAs, such as reducing brittleness. This could suggest that the properties of current PLAs are not good enough for mass use, and it will be interesting to see if improvements in the technology result in increased interest in PLAs. One strategy used by the LG Chemical group to improve the tensile strength and transparency of PLA is to form block copolymers including a polylactic acid block and a polyhydroxyalkanoate block in a carefully controlled ratio.
Figure 4: Ten-year filing activity: top ten filers – PLA
Polyhydroxyalkanoates (PHAs), such as polyhydroxybutyrate (PHB), are produced by microorganisms via the fermentation of biomass. Production costs for PHAs are currently high, but we can speculate that innovation in this area may lead to a reduction in costs.
Global patent activity
The countries seeing the largest numbers of PHA-related patent filings over the last two decades have been Japan and the US. Filing numbers in the US have generally been more stable than those in Japan, while South Korea has filed a considerable number of patent applications.
While the overall number of filings in the top five jurisdictions do not follow a smooth trend, filing numbers have notably increased since 2015, suggesting a renewed interest in PHAs.
Figure 5: Twenty-year trend: top five filing jurisdictions – PHAs
Kaneka Corporation, based in Japan, has been the dominant source of patent filings in PHAs since 2018 and is the only one of the top ten filers over the past 10 years to have filed applications every year. This has included applications relating to a variety of aspects of PHAs, such as production methods, mechanical properties, and shaped articles. For example, Kaneka has developed a bioplastic fibre with improved tensile strength containing a PHA and polycaprolactone. Other notable filers include Italy-based Bio-on S.p.A. and South Korea-based CK Cheiljedang Corporation.
Figure 6: Ten-year filing activity: top ten filers – PHAs
Starch has poor strength and thermal stability and, as such, is not used as a “plastic” itself. However, starch (in particular, thermoplastic starch) has been blended with other biodegradable polymers to produce bioplastics.
Global patent activity
In contrast to the trends seen for the other types of bioplastics, the US has been the biggest source of patent filings relating to starch-based polymers over the past twenty years. Even so, the number of filings per year in the US has fallen since around 2014. In other jurisdictions, such as Europe, South Korea and Japan, patent filings have also been lower over the past 10 years than the preceding decade. We could speculate that this lack of – or at least reduced – interest is because starch has poor properties compared to other bioplastics. However, there has been a slight – but notable – uptick in filing numbers since 2017. It will be interesting to see if this continues as the technology improves.
Figure 7: Twenty-year trend: top five filing jurisdictions – starch
Daesang Corporation, based in South Korea, has been responsible for the largest number of patent filings relating to starch-based polymers in the past 10 years, although most of its filings are concentrated between 2012 and 2015. Daesang has filed patents related to various uses of starch-based polymers in packaging, again suggesting increased consumer demand in this area. Recently, Daesang has developed a starch-based bioplastic with improved tensile strength, elongation, and tear strength, by grafting starch with polybutylene adipate terephthalate (PBAT). Other notable filers in this area include Roquette Frères, based in France, and the US-based Procter and Gamble.