Mechanical decontamination of plastics
A process for the removal of organic contaminants (NIAS) from recycled plastic materials operating at atmospheric pressure using a non-volatile, water-soluble extracting agent.
The packaging sector has the highest demand for plastic materials: with PE, PP, and PET resins contributing to 84% of post-consumer plastic waste. Among these, HDPE and PET bottles demonstrate the most efficient collection rates, with 76% and 79% respectively. However, only post-consumer PET can be recycled and reused for food-grade applications due to the existing commercial decontamination process authorized by the European Food Safety Authority (EFSA). Unfortunately, there is no approved mechanical decontamination of plastic authorized to process post-consumer HDPE or PP recycled bottles to be used in food contact applications.
Why have only mechanical decontamination processes for post-consumer recycled PET been successfully applied in the industry?
PET is considered a glassy polymer at room temperature and under most conditions of use, whereas polyolefins exhibit rubbery properties and possess poor functional barrier characteristics. The diffusion coefficient of substances is significantly lower in PET compared to polyolefins, making the potential migration of absorbed contaminants much less likely in PET. Additionally, polyolefins have lower thermal stability than PET, resulting in the formation of degradation products during processing. Stabilizers, employed to protect polyolefins from oxidation and degradation, can also generate reaction byproducts. This becomes particularly crucial when the materials undergo multiple recycling and processing cycles, as newly formed substances from both the polymers and stabilizers may migrate into the packaged food.
Food grade packaging is not exclusively made from PET; it also encompasses various types of PE and PP. Therefore, it is crucial for the industry to seek innovative solutions that can achieve an equivalent level of decontamination in polyolefins as that achieved in PET.
There is growing interest in utilizing recycled post-consumer HDPE and PP in packaging for home, personal care products and interior vehicle parts. Some brands have already expressed their intention to produce bottles using post-consumer recycled HDPE for body care products, which follows the same legislation regarding contaminants as food contact plastic packaging.
As the demand for high-quality recycled polymers increases, advanced mechanical decontamination processes are gaining attention in research and in the industry. These processes include techniques such as supercritical CO2 extraction applied during or after extrusion, hot air extraction, and the addition of adsorbents in a compounding unit. However, none of these technologies can remove 100% of contaminants, and none of them are authorized by the EFSA as decontamination methods for producing food-grade polyolefins.
Food-grade recycled plastic materials and articles can only be sold if the decontamination recycling processes used are authorized. The EFSA's safety opinion is required before a process for mechanical decontamination of plastic can be authorized.
Currently, only the chemical recycling of polyolefins is authorized to produce new recycled polyolefins from recovered oils. However, none of the mechanical recycling methods proposed for polyolefin decontamination have been authorized by the EFSA. This presents a significant challenge in meeting the EU's target of introducing 30% recycled content in plastic packaging by 2025, particularly for food-grade polyolefins.
At Fych, we propose a novel solution to extract contaminants absorbed in polyolefin matrices using environmentally friendly solvents. This is a mechanical decontamination process that uses green solvents that have low volatility, are non-toxic, and water-soluble. Unwanted contaminants present both within and on the surface of the recycled polyolefins are diffused into Fych Green Solvent, reducing their concentration in the plastic to a safe level. This innovative technology enables the cost-effective decontamination of plastics, boasting an operating cost that is less than 25% of the expenses associated with chemical recycling.
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