The fourth edition of “Inside Green Innovation: Progress Report” also found that the number of patents filed for international reach has fallen by almost a quarter. The firm attributed this to a difficult economic climate.
Geographically speaking, multiple countries have increased bioplastic patent filing numbers with South Korea more than trebling its patent filings from 2020-2022 – likely because of government targets for reducing plastic waste. 
In terms of plastic type, while former leader polypropylene (PP) has shown growth in 2022, the largest momentum is currently around recycling polyvinyl chloride (PVC), followed by polyethylene terephthalate (PET). PP has moved to the third spot but is still some way ahead of the next most common materials low-density polyethylene (LDPE) and high-density polyethylene (HDPE).
Partner at Appleyard Lees, Chris Mason, said: “The global high for bioplastic patent filing, despite a difficult economic climate, reflects the level of demand for this potential solution to the ‘plastics problem’. Innovators are also responding to the criticism that bioplastics that break down only under industrial composting conditions are not suitable for addressing plastic pollution in the natural environment, seeking to find bioplastics with the right combination of biodegradability and mechanical properties.
“And we expect the increasing trend for innovation in chemical recycling technologies to continue, given growing pressure on manufacturers to embrace a sustainable, circular plastic economy and the need to close the gap between the amount of plastic waste produced and recycled.”
An increase in chemical recycling
Notably, annual patent filings in the chemical plastic recycling space have risen by over a quarter with almost 700 filings in 2022. This represents a 350% increase in five years.
Amelia Barton, Patent Attorney, explained: “Among chemical recycling technologies, pyrolysis continues to claim the bulk of patent filings – increasing by almost one-third (32%) in the year to 2022 and a more than six-fold increase on five years earlier.
“And while there has been comparatively lower patent activity in technologies involving metal-catalysed depolymerisation and supercritical water, both have shown significant recent increases (28% and 20% respectively), with metal-catalysed depolymerisation in particular recording a fourth-straight year of 20%-plus growth. Meanwhile, innovation in microbial biodegradation has also increased, with filings relating to micro-organisms able to degrade plastics, for example.”
A growing trend towards PHAs
The report found that bioplastics made with polyhydroxyalkanoates (PHAs) have shown the sharpest increase at 58%.
The bioplastic is made of sugars grown from algae have now overtaken butylene-based polymers and now sitting behind polylactic acid (PLA) in number of patents.
PHAs are able to biodegrade in the natural environment without composting and have also been found to have several commercially viable physical properties.
In contrast, PLA-based bioplastics require recycling or industrial composting to break down while butylene-based polymers tend to be derived from petrochemicals.
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