We want packaging to protect, protect consumers and conserve material resources. We want to use barriers that reduce the penetration of gases (carbon dioxide and oxygen) and moisture for sensitive products. We want to use colors and UV inhibitors to protect against loss of vitamins and taste. We might even want to lighten up our package a little.
Then we want our packaging back. Recycling efforts cannot be considered successful until we have returned the containers, bottles, bags, etc. – and this remains a challenge, especially in the United States.
But what do we do with it when we get it back?
The previous mode of attack is mechanical recycling. The process separates materials by type: glass, metal, paper and plastics. Today it is relatively easy to set up a mechanical recycling facility and reclaim many materials for the next generation.
In the case of plastics, however, mechanical recycling can only get us so far. The starting materials cannot differ much from the original polymer. These materials that we add to improve packaging performance – such as nylon, paint, oxygen scavengers – can negatively affect the processing and appearance of mechanically recycled polymers.
PTI / PlasticsToday
That takes us to the next level. In order for the circular economy for packaging to work, we need chemical / advanced recycling technologies that work and are economical. Advanced recycling makes it possible to convert raw materials for plastic packaging that differ from the original polymer and are undesirable for mechanical recycling into high-quality resins.
There are three main areas of advanced recycling, each offering a different degree of polymer degradation and, in theory, a different degree of raw material purity:
Cleaning. Plastics are dissolved in a solvent that is specially tailored to the polymer to be regenerated. The pure target polymer is extracted and impurities such as additives, dyes, barrier material can be filtered and removed. The result is a pure polymer that can be reused. Technologies with a focus on polypropylene and polystyrene are currently in use. The feed may have more impurities than mechanical recycling can handle, but ideally contains mainly the target polymer with limited impurities.
Decomposition. Plastics are broken down into their monomers and intermediate products and the process enables the impurities to be removed. These monomers and intermediates can be used to make a new polymer. There are several technologies that focus on PET. The feedstock can have more impurities than mechanical recycling and cleaning technologies.
Conversion. Plastics are broken down further than when they are decomposed, and hydrocarbons are formed that can be used as raw materials for the manufacture of new monomers, intermediates and polymers. These raw materials do not necessarily have to be used to make the same polymer they are made from and can use a much broader polymer raw material than purification and decomposition.
Why don’t we get what we want?
These technologies bring challenges that take time to overcome. According to the Closed Loop Partnership “oFor the 60 technology providers surveyed, it took an average of 17 years for growth to be achieved. Additionally, more mature companies are typically the ones that make fuels and petrochemicals from plastic waste. Those who make polymers are on average at an earlier stage. “
Scaling up to production is difficult. Most of these technologies start with a hypothesis and 10 grams of material in a benchtop beaker in a laboratory. Turning this idea into an industrial plant that can produce thousands of pounds per hour requires enormous scientific, technical, and financial resources – and time.
If we want our plastic back, we need to promote, support and invest in programs to promote these technologies and use the materials produced to drive demand.
Dan Durham is Director of Technical Client Services at PTI. He has decades of experience in the field of plastic packaging from design to injection molding and blow molding. He is currently focused on helping multinational brand owners successfully manage packaging projects from concept to marketing and support their sustainability goals.
PTI is recognized worldwide as a major source for preform and packaging design, packaging development, rapid prototyping, pre-production prototyping, and material evaluation technology for the plastic packaging industry. Further information: www.pti-usa.com.