Polypropylene is a popular, widely used packaging resin, but it often faces challenges when it comes to being recycled. Still, its properties make it very desirable. The resin is durable, lightweight and can deliver high clarity so much in demand for food and beverage packaging. It also is one of the least energy-intensive polymers to make and recycle compared to other clear polymers.
Global demand for polypropylene (PP) is about 90 million metric tonnes, with its usage has grown on average by 3.5 to 4% per year over the past decade, according to Esteban Sagel, principal of Houston-based Chemical and Polymer Market Consultants. Other analysts forecast similar growth continuing in the years to come.
Brazilian chemical engineer Victor Sanfins Cecon, who is currently pursuing a Ph.D. in food science and technology at Iowa State University in the US, revealed a startling statistic in his recent talk at the Society of Plastics Engineers’ ANTEC conference in Denver, Colorado. He was disclosing findings from his ongoing study about the types of plastics found in various material recovery facilities (or MRFs) in the Midwestern U.S.
Citing US Environmental Protection Agency data about the resins being recycled from municipal solid waste streams, he noted that PET and HDPE plastics are recycled at the highest rates – 17.2% and 8.9%, respectively. Comparatively, the EPA data show, just 8.5% of all plastics being generated are recycled, and the popular PP packaging resin is being recycled at a paltry rate of only 0.6%.
This is in part because PP often is used in combination with other resins and barrier layers that make the overall package incompatible with most recycling streams.
Brand owners and packaging processors are working hard to address this issue by finding ways to make mono-material PP constructions that can be more easily recycled. Several companies showcased their efforts at the interpack 2023 fair.
Making things perfectly clear
Spartanburg, South Carolina-based Milliken & Co., a leading additives and colorants producer, says its Millad NX 8000 clarifying agent yields PP resin with glass-like clarity. This makes it a viable replacement in packaging applications that currently tend to use PET, polystyrene, or polycarbonate.
Milliken touts how its Millad NX 8000 ECO grade is used to produce NX UltraClear PP resin, which allows injection molders who use the material to process at lower temperatures and reduce their energy use during production by up to 10% on average compared to conventional clarifiers. The result? Faster cycle times, higher productivity and reduced CO2 emissions. By broadening PP’s potential range of applications, Milliken says the resin helps to enable mono-material package constructions.
Certifiably circular pasta packaging
SABIC, meanwhile, announced that Pastificio Lucio Garofalo, a prominent Italian pasta maker, has introduced novel packaging made using SABIC’s certified circular polypropylene from its TruCircle portfolio of resins.
The Saudi Arabia-based chemical giant calls the product the first mono-material PP pasta packaging on the market. It contains 30% post-consumer recycled (PCR) content, which SABIC turns into pyrolysis oil in an advanced recycling process.
SABIC uses that ‘pyoil’ to produce new polymers with the same specifications as virgin plastics from the conventional feedstock. Portugal’s Polifilm Polivouga Industria de Plasticos applies the resulting polymers from SABIC to produce a basic biaxially oriented polypropylene (BOPP) film for this application.
Italy’s GT Polifilm then adds a cast PP film to the BOPP film to create a mono-material structure, which is then converted to tailor-made pasta bags. Once used, SABIC notes, the mono-PP bags can easily be recycled again in existing PP waste streams.
Garofalo introduced the first pasta bags made from the new packaging to Italian stores in March 2023.
Various mono-material options
Finnish packaging giant Huhtamaki in late April rolled out new mono-material packaging solutions in paper, polyethylene and polypropylene retort formats.
Dr. Marco Hilty, president of flexible packaging at Huhtamaki, said the new materials are designed for recycling and use fewer materials than the conventional complex and multi-layered materials they have been created to replace.
Huhtamaki says its new innovation enables it to provide mono-material flexible packaging in three alternative material solutions – paper, PE (polyethylene) and PP (polypropylene) retort – with each fit for the most demanding applications. With a mono-material share of up to 95% for PE, and at least 90% for paper and PP, the new solutions offer no compromise in protection barriers, recyclability or affordability.
“We have simplified previously complex structures using fewer materials and without the need for an aluminum layer or other barriers with different materials,” explained Hilty. “This breakthrough will, therefore, increase the value of post-consumer material, providing a greater economic incentive for recycling and supporting circularity.”
Huhtamaki said it has invested in new production technologies across its production footprint, building a global supply capacity for these new products. “I am extremely proud to share that Huhtamaki is now ready to launch our new, unique innovation at scale, globally.”