PolOne's blow moulding machine

A process that enables blow moulders to co-extrude high-density polyethylene (HDPE) bottles layered with thermoplastic elastomers (TPEs), has been developed by PolyOne, headquartered in Cleveland, USA.

The technique can be used with traditional or recycled HDPE and is said to expand the possibilities for designers to create soft touch or non-slip surfaces on packaging to help differentiate products.

‘Multilayer extrusion and blow moulding is not new,’ says Rick Noller of PolyOne, ‘but until now, no one has adapted the process for TPEs as it was not economically viable.

Though Noller is unable to go in to detail regarding the new method, he says the technology will help companies curtail their costs.

‘Our proprietary extrusion technology enables customers to keep material costs equal to or even below the cost of HDPE alone,’ he continues. ‘We achieve this by minimising the amount of TPE needed for the desired effect, reducing the amount of masterbatch needed by colouring only the TPE or the underlying HDPE, and using recycled resin where appropriate.’

He says the tactile layer can be added without the need for a separate coating process.

‘Our solution adds design possibilities ranging from customising the degree of non-slip “grip” for safety or ergonomic reasons, to adding a soft touch for enhanced aesthetics’, explains Noller. ‘It also provides the option of colouring the TPE layers or allowing coloured HDPE to show through a translucent TPE layer.’

According to Noller, the process can accommodate up to seven layers, providing opportunities to add an oxygen barrier or other coatings.

‘Packages may be designed, for example, with an inner layer of virgin HDPE for food contact compliance, a middle layer of recycled HDPE and an outer layer of TPE. Layers are co-extruded and bonded together before blow moulding into a bottle or other part.’

Stuart Patrick, a polymer specialist, says that the technology could be highly beneficial to the packaging industry, so long as the multilayering process does not prevent the materials from being recycled.

‘Separating materials in the waste stream already presents a number of challenges,’ he says. ‘It is worthy to be able to use recycled materials [to produce new packaging], but the multilayer material should also be able to be recycled.’

PolyOne are looking into this issue.

Further information

www.polyone.com