New additives to cut resin processing costs

A range of additives that allow extruders to improve melt strength, increase throughput and reduce costs when processing polyester resins has received FDA sanction for food-contact packaging applications. Clariant claims that its CESA-extend additive masterbatches can significantly improve processability when used with lower viscosity polycondensate resins, like PET, recycled PET (RPET) and/or regrind.

A range of additives that allow extruders to improve melt strength, increase throughput and reduce costs when processing polyester resins has received FDA sanction for food-contact packaging applications. Clariant claims that its CESA-extend additive masterbatches can significantly improve processability when used with lower viscosity polycondensate resins, like PET, recycled PET (RPET) and/or regrind. Any cost-effective increase in performance would be welcomed by an industry facing high raw material costs. The additives utilise an oligomeric reactant (Joncryl ADR 4368 from Johnson Polymers) restore the resin#s intrinsic viscosity. Increased melt strength results in a stiffer extrudate that is less prone to sagging. The use of post-industrial and post-consumer polyester regrind has typically been limited due to the adverse effect of heat history and moisture-related degradation. These lower-cost, environmentally friendly materials could not be used without time-consuming pre-drying and careful attention to process set-up, which, in turn limited production efficiency and throughput, and reduced product quality. But Basel-based Clariant claims that CESA-extend masterbatches can be produced using a variety of carrier resins and additive loadings. In addition to their suitability for polyesters, they also increase the molecular weight and processability of PC, TPU, polylactic acid and nylons. The benefits these new additives bring to processors, says the company, are evident. In one application of CESA-extend, Clariant claims that a PET sheet producer projects six-figure annual cost savings.