PET promises new option for handleware

A new PET resin from Indorama Ventures Public Co. Ltd. could change the way you snack.

Polyclear EBM PET, produced by Indorama-owned Auriga Polymers, can be used to make containers boasting glass-like clarity, high gloss, and handles, said Frank Embs, director of business development for Auriga, to a crowd at The Packaging Conference.

The resin was developed for extrusion blow molding applications and can run on existing machines and molds. In one of Polyclear’s first commercial applications, Denver-based CCW Products Inc. used the resin to make wide-mouth jars for H.K. Anderson Pretzel’s peanut butter filled nuggets, Embs said.

Anderson was looking for a recyclable, high clarity, high-gloss container to replace its current PVC or glycol-modified PET jars. With some adjustments and alterations to equipment and processes, Polyclear fit that criteria, Embs said.

Polyclear is a semi-crystalline, high melt PET variation, and must be processed at a higher temperature than regular PET. In initial runs on a Bekum shuttle machine, containers had problems with poor melt strength, un-melts, runny sleeves, a lack of clarity and a weak finished product. By making alterations to machines and molds, the company was able to solve the problems, Embs said.

The material, like other polyesters, must be dried before processing, and must reach and maintain a moisture level less than 20 parts per million. To meet these requirements, the company installed a large dryer, and attached a small hopper to the top of the machine that feeds the material into the extruder at the correct temperature and moisture level. The resulting containers were actually less brittle following the alterations, Embs said.

The materials high melting point, 230° C, led to the addition of 1,000-watt heater bands to the barrel. But, the hotter, stickier PET parison stuck to the existing blade knifes during cutting. A hot knife was used to cut the material at commercial speeds.

Along with reaching the correct temperature, the material must be processed in the correct time frame. Using PETG-type low-shear screws or PVC barrier screws led to unmelts, barrier screws also resulted in low melt strength. Regular PVC screws created too much shear and runny sleeves. To combat the problem, the company used a hybrid-barrier screw, and modified the temperature profile to increase back pressure and effectively mix the melted polymer and un-melted crystals, Embs said.

Polyclear crystallizes similar to PET, but it’s a stronger polymer with a higher parison temperature.  To speed up cooling and avoid crystallization, cooling channels were added to existing molds. The creation of longer cooling belts and blowers prevented the containers from sticking to the trimmer. The original pinchers couldn’t cut through the polymer, so they were replaced with stronger stainless steel ones.

The new containers were required to meet top-load requirements, but the original designs failed crush tests, Embs said. After some alterations, like fixing the weight distribution to eliminate weak spots, the container had zero failures, Embs said. The product has also been available on store shelves for more than a year and has had no failures in use, he added.

The resulting container is recyclable and carries a PETE 1 designation. It can also be made using up to 60 percent internal regrind if the regrind is dried and crystallized, Embs said.

“The Anderson Peanut Butter jar is a great success,” he said.

Though the peanut butter jar doesn’t call for them, Polyclear PET containers can be made with handles, making them ideal for beverage packing, Embs said.

Indorama plans to launch more commercial applications for the material this year, including one for orange juice, he said.