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additives feature | Polymer foams

Clariant’s Hydrocerol CFA formulations allow much smaller cells – for example, the average cell size shown on the right is 91 microns compared to 181 microns for the traditional formulation on the left

quality of appearance, and cost savings. “In the past, foaming has been often used as a ‘band-aid’ for moulded parts with thick walls and diffi cult fl ow paths, but now we see optimization of chemical foaming usage in automotive and other markets as a substantial cost and raw materials reducer,” says Peter Schroeck, technical director of Reedy International. “New patented processes are taking advantage of the easy implementation of chemical foam in composites and glass fi lled polymers and are achieving substantial performance and process improvements while inching closer to lofty Corporate Average Fuel Economy goals,” he adds. Reedy, which supplies endothermic and endother-

mic/exothermic blends, recently introduced Safoam PN-40E, an endothermic chemical nucleating and foaming agent compatible with both styrenics and olefi nics. The new product has improved bubble size and gas retention, which can result in improved fl ex and compression in thermoformed parts, says the company. Clariant Masterbatches discussed its improved Hydrocerol CFA masterbatches in a presentation at AMI’s Polymer Foam 2012 conference held in Newark, New Jersey, USA, in October. Frank Neuber, applica- tions development manager at the company, explained that the new masterbatches use carrier systems that create earlier polymer fusion onset. This enables better distribution in the mix, improved cell-wall integrity, and improved encapsulation of the gas that is generated to create a better foam structure.

ColorMatrix says its

Excelite liquid foaming agent creates very smooth PVC sheets suitable for digital printing

In addition, Clariant has optimized nucleation to create smaller and more uniform cells that allow the use of additional CFA to achieve greater density reductions without signifi cant loss of physical integrity or appearance. Processors can incorporate best practices, such as using accurate feeding systems, ensuring consistency between shifts, incorporating stabilizers when adding regrind, and using a consistent resin to further improve their cost savings. These practices are not always used, said Neuber, but they can have a positive effect. Clariant works with customers on their shop fl oors to improve practices and optimize

38 COMPOUNDING WORLD | January 2013

processing conditions to obtain the best possible foaming. These new Hydrocerol masterbatches are optimized

for specifi c resins, processes, and applications. The goal is to create the most effective foam cell structure to maximize both density reduction and physical properties and surface appearance, says Kirk Jacobs, product line director for additives at Clariant Master- batches North America. Different resin types and grades perform differently

in the foaming process and thus require not only compatible carriers but different types and levels of blowing agents, nucleating agents, and other additives, notes Neuber. The end application also needs to be taken into account. For example, thin-walled, thermo- formed cups require very small cell sizes. Several new Hydrocerol CFA masterbatches are now commercial, including products for: automotive applications involving TPO, PP, and nylon; thermofor- med polystyrene packaging; injection-moulded

polyolefi n closures; and fl exible fi lm and tube polyolefi n packaging. In extrusion blow moulding (EBM) applica- tions, Hydrocerol masterbatches are being used successfully in non-appearance parts such as vehicle ductwork. Appearance-sensitive EBM applications in food and personal-care packaging require better surface aesthetics, and Clariant is working with several customers on masterbatches fi ne-tuned for these applications.

ColorMatrix, a subsidiary of PolyOne, supplies

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