Polyplastics, Colgate-Palmolive and PTI presented a new method for manufacturing high-density polyethylene (HDPE) bottles at The Packaging Conference in Austin, Texas. The technology is based on injection stretch blow molding (ISBM), known from the production of widely used PET bottles for water and carbonated soft drinks. It has been adapted to efficiently manufacture thin-walled, attractive and hot-fillable HDPE bottles.
At present, almost all HDPE bottles are produced by extrusion blow molding (EBM), a process characterized by relatively long cycle times and typically resulting in excessive container weight, for example in the base area. With the new technology, significant reductions in bottle weight and cycle time, exceeding 25%, have been demonstrated. The solution consists in adding a second component to HDPE. This component is an ethylene copolymer from Polyplastics, known as Topas COC (cyclic olefin copolymer), which significantly broadens the processing window of HDPE, making ISBM practical and efficient while maintaining the recyclability of the finished container.
Topas COC is widely used in the packaging industry in combination with polyethylene (PE) to enhance performance properties, as well as in medical applications where very high material purity is required. In the new HDPE bottle concept, this material acts as a modifier that enables stable injection stretch blow molding and the production of thin-walled, lightweight structures with adequate strength.
Application of COC in lightweight HDPE packaging
Colgate-Palmolive is investigating the use of COC to develop high-performance packaging that also meets increasing regulatory requirements for unit weight reduction. The company indicates that results to date are encouraging and announces further work aimed at commercialization. The objective is to combine lower material consumption with the required functionality of the package, including resistance to hot filling.
Polyplastics has carried out an extensive testing program at PTI's development facility in Holland, Ohio. PTI has confirmed the suitability of the new technology for hot-fill processes. The testing included evaluation of the behaviour of HDPE bottles modified with Topas COC during hot filling, as well as assessment of dimensional stability and mechanical properties at reduced article weight.
Implementation prospects and application areas
PTI expects to work with several brands to prepare for the commercial launch of HDPE bottles manufactured using ISBM. The technology is expected to be applied in packaging for cosmetic, food, medical, household, industrial and general packaging uses. The combination of reduced weight, shorter production cycle and confirmed hot-fill capability is intended to enable the design of more efficient HDPE packaging that complies with current market and regulatory requirements.
