A new US study has revealed that plastic bottle makers can use up to 50% recycled PET (rPET) content in hot-fill bottles without causing a “significant adverse impact” on the containers' integrity.
Research by design and technology company Plastic Technologies (PTI) of the US delved into the issue of rPET because the company said brand owners continued to look for ways to lower their carbon footprints.
“With increasing demand for rPET use, there have been general questions raised on how well rPET works in higher performance packaging,” said Ron Puvak, director of marketing and new business development at PTI.
“As part of our thought leadership position we felt it was a worthwhile project to understand the limitations for use in specifically hot fill packaging.”
Puvak said rPET was being used in “limited amounts” for hot-fill applications at this point. “The level of rPET use is normally a self-imposed brand owner specification.”
“We have proven that higher levels do not impact performance, which was the goal of the exercise,” he added.
PTI studied recycled PET resins at 25%, 50% and 100% levels in 500ml bottles and preforms weighing 27g.
“Even at 100% rPET resin use, the performance of the bottle used in this study was still acceptable,” said Tracy Momany, vice president product development group at PTI, in a statement.
“However, the typically thicker walls of hot-fill bottles may result in slightly more noticeable haze or yellowing than other applications such as very thin-walled water bottles.”
PTI tested areas including top load performance, wall thickness, colour, haze, crystallinity and acetaldehyde content.
Shrinkage increased slightly when the recycled content went over 50%, but the bottles still met specifications, PTI reported.
Drawbacks, the company said, included that yellowing and haze increased with high rPET levels, but “companies using hot-fill bottles that are looking to improve their environmental profile can confidently use up to 50% rPET content in their PET bottles without negatively impacting performance.
“The aesthetics of the package will dictate the level of rPET acceptable for a particular application,” it added.