ADDITIVES FOR FILM | MATERIALS
Recycling demands Meanwhile, SI Group reports increased demand for and incorporation of recycled resin into formulations across applications, as well as an increasing awareness at film recyclers regarding the importance of antioxidants to protect the polymer from severe degradation during recycling. “When dealing with post-consumer streams, it is important to prevent the gel formation as early as possible during the recycling process,” said Jeroen Frederix, market development manager for circular economy at the company SI Group’s Evercycle LD-101S is said to be an
easy-to-dose, non-dust-blend (NDB) for recycled LDPE/LLDPE (referred to as rL(L)DPE by SI) streams that can protect the polymer during mechanical recycling. Frederix says that if a recycler switches from using a stabiliser in masterbatch form to the NDB form, they can lower the dosage and elimi- nate the carrier resin, which is often virgin plastic. Evercycle LD-104P is a masterbatch that can be applied in either — or both — of the recycling and converting steps when working with rL(L)DPE resin. The masterbatch has been shown to benefit blown film converters by improving bubble stability at higher loadings of PCR material, Frederix says. In cast stretch film extrusion, the masterbatch helps improve mechanical performance and allows increased recycled content. In particular, for adding post-industrial recycle to stretch film formulations, the company says the masterbatch has been found to improve the final stretch film performance when added during film extrusion. Roberto Nunez, market development director for special additives at Baerlocher in the US, says
that Baeropol T-Blends are a family of products intended to be added during film recycling to alleviate some of the problems experienced when using post-consumer recyclate (PCR). The additives are said to reduce additional gel formation and provide a more stable melt flow, for example. T-Blends are available as a 100% active-content, dust-free pastille that can be dosed alone or dry-blended with masterbatch or polymer. To prevent gels and stabilise melt flow in compounds that contain recyclate, Dover Chemical recently introduced DoverClear 800, a recycling- grade antioxidant based on its Doverphos LGP12 — a liquid secondary antioxidant that was intro- duced as an alternative to TNPP more than a decade ago. Shawn Cook, technical manager for plastic additives at the company, says the additive is optimally added during compounding of the recycled material to prevent gels in the subsequent film extrusion step. Data shows that LGP12 can prevent or reduce
large gels that can cause tears in films. In a large trial, LGP12 was shown to near eliminate gels in a compound made with post-industrial recyclate (PIR) and significantly reduced them in a compound made with PCR [Figure 1]. In addition to acting as an antioxidant to prevent polymer degradation, the additive has a lubricating effect that can further prevent larger gels by reducing material-hangups in dead-spots, Cook says. DoverClear 800 is offered as a masterbatch of up to 8% loading, with typical final product loadings of 0.5-4%. It has FDA food-contact approval in LLDPE and HDPE. Polymer processing aids (PPAs) are widely used to prevent melt fracture during film processing.
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