New additives to cut resin processing costs

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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

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.

The FDA-approved melt viscosity modifiers allow line speeds up to 12 per cent higher and allowed regrind percentages to be increased from 25 per cent to 50 per cent. The increased melt strength resulted in a stable process, requiring less set up time when different resins are run on the same extrusion line.

The higher melt strength also reduced sagging and improved surface appearance.

Cost-effective packaging is vital at a time when energy prices are at an all-time high. The root of problem is that the cost of natural gas and petroleum, the starting point for the production of many types of packaging resins, has increased consistently over the past 12 months.

Oil-based resin used in plastic packaging has increased in price by seven per cent over the past six months, suggesting that the price increase trend is far from abating.

These price increases have hit firms that rely on plastic for packaging. Pepsi bottling group for example reported last month that net income for the first quarter 2005 was $39 million, compared to 2004's first quarter income of $50 million. This is the first time that quarterly profit has fallen in almost two years.

Clariant Masterbatches products are marketed under six global brand names: Remafin masterbatches for olefins; Renol masterbatches for engineering resins, styrenics and PVC; CESA additive masterbatches; Hydrocerol chemical foaming and nucleating agents; Omnicolor universal colour masterbatches; and Enigma special effects.

The food contact sanction allows the CESA-extend additive masterbatches to be used in the production of food packaging in accordance with FDA inventory of effective pre-market notifications for food contact substances, FCN #429.

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