If you’ve ever purchased bottled water, you might notice the tiny recycle sign embossed to the bottom of the bottle. If you saw the number one in the middle of the triangle alongside the letters P, E, and T, chances are the plastic bottle you’re holding is made from PET (polyethylene terephthalate).
This durable and lightweight material can be found on store shelves, kitchen cabinets, freezers, and even in pharmacies. PET film is transparent, strong, and non-toxic — making it the perfect material to protect your favorite snacks from getting crushed mid-transport or from going bad before their expiration date.
How does the versatile material go from raw materials to the clear, protective film we see on store shelves? Let’s delve into the fascinating world of PET film production.
Transforming Raw Materials into Liquid
While raw material mix may differ from each manufacturer, the journey starts with mixing terephthalic acid (PTA) and ethylene glycol (MEG). These two substances are the building blocks of PET and can also be found in the naphtha cracking chain. PTA and MEG are then brought together in a reactor under controlled conditions. Then, a chemical reaction called polymerization occurs, where individual molecules of PTA and MEG link together to form long chains known as the PET polymer.
Polymerization is where lower molecular weight materials are combined using high temperatures and/or other catalysts to form polymers. Then, solid PET polymers are melted into a more manageable form by feeding them into an extruder.
Achieving Strength: Biaxial Orientation
The amorphous polymer is then biaxially oriented by a process called drawing. The film is stretched in two directions, lengthwise and widthwise, simultaneously. This will align the PET polymer chains which help strengthen the polymer, increase clarity, and reinforce its barrier properties.
Depending on the intended application, the film might undergo further processing. This could involve adding coatings for extra protection against moisture or oxygen, printing for branding purposes, or even metallization for specific barrier properties.
Finally, the finished product will undergo rigorous quality checks to ensure it meets strict specifications. The film is then wound onto large spools, ready for conversion into the various packaging formats we encounter in our daily lives.
From the water bottles you grab on the go to the blister packs holding your favorite medicine, chances are you have seen packaging made from PET in your day-to-day lives. Research focused on improving PET sustainability through increased recycling rates, incorporating recycled content into the film itself, and developing biodegradable alternatives will contribute to the ever-evolving industry.
As technology advances, PET film packaging is likely to remain a vital player in the quest for safe, convenient, and environmentally conscious packaging solutions. As a key player in the industry, PT Argha Karya Prima Industry has developed a mono-material method that allows their films to be easily recycled after branding. For more information on their eco-friendly plastics, visit PT Argha Karya Prima Industry (https://arghakarya.com)