Hot-fill PET container sets new standards, says company

Liquid Container said its newly developed Thermaset PET line of stock and custom jars is the first to offer what it calls “sustained hot-fill performance​” at 205° Fahrenheit – an attribute that makes it suitable for viscous food items such as sauces, jams, jellies and tomato-based products.

Less shrinkage​

The containers are manufactured using a specially developed method that substantially increases the PET's glass transition point and results in sustained thermal stability.

“Our container can withstand sustained temperatures of 205ºF with less than 1 per cent shrinkage,” ​Mark D. Schneider, the company’s senior director of PET technology group and R&D, told FoodProductionDaily.com.

He added: “This is a significant improvement over the current market. Typical shrinkage seen from current market containers hot filled at 205ºF is between 1.5 per- 4 per cent. When you consider filling temperature spikes of greater than 205ºF the percentage of shrinkage can even be higher.”​

The ability to avoid shrinkage is critical, as “lack of dimensional control”​ can result in performance line issues, rework and food safety concerns that can affect everything from finish/seal integrity to labelling, he said.

The Thermaset line is based on a process developed by the company. It uses standard bottle-grade resins but contains no additives or enhancers to boost thermal performance characteristics.

“Our proprietary process which changes the thermal characteristics of the PET involves all aspects of moulding the finished article. This involves, but is not exclusive to, moulding the preform, preform design, reheating, conditioning and stretch blowing,”​ said Schneider.

This method also leads to an incremental improvement in barrier protection. Depending on container design, Liquid Container said oxygen barrier performance had been increased by between 8-15 per cent.

A further design feature is a strengthened base that can absorb pressure and vacuum, which minimises distortion during cooling, said the company.

Advantages​

The new containers offer a number of advantages over current products including a reduction in packaging material and enhanced ease of use for the consumer.

Schneider said: “Since the container stays rigid through the thermal process it opens up the opportunity to lightweight, incorporate non-conventional designs, eliminate or minimize structural ribs typically found in containers like this which will improve product evacuation of viscous products, and maintain glass like clarity.”​

The product, which is patent pending, is expected to come to market in 2010.