processing | Purging compounds
Difficult solutions Jeff Lewis, Sales and Technical Manager at US-based Slide Products, says there is a growing need for purging compounds that operate effectively in more difficult environments. “The constant development of plastics resins that are increasingly used for structural compo- nents mean that the additives and moulding tempera- tures will push purging compounds to be much more aggressive and efficient,” he says. “One of the more common questions I get asked
Above: Faster purging is a key customer demand, according to Shuman Plastics, Dyna-Purge Division
more value with additional product utility. “In extrusion and compounding that means offering grades that can deliver results on a wide range of equipment, as well as to work easily at the laboratory level where benefits from purging would be beneficial too,” says Kelli Ropach, International Business Manager at Shuman Plastics, Dyna-Purge Division. “Generally, commercial purging products have
addressed the bulk of compounders’ needs in the commodity areas, but it is at the margins where development is evolving. Special effect pigments, high intensity colours, flame retardants, bio-fillers and bio-polymers are all driving product development, as are new high heat speciality resins. In addition, clients pushing for greater yields and productivity are demand- ing products that purge faster and are more self-elimi- nating, which is why we developed one of our newest grades, Dyna-Purge A,” Ropach says. Designed for purging polypropylene, it is the
Right: Purging
compounds can considerably speed colour and material changeovers
company’s first purging compound to combine key features found in both mechanical and chemical products. This new hybrid technology is claimed to be ideal for eliminating colour streaks and other forms of contamination associated with purging polypropylene out of a screw and barrel (as well as the tool and die). The compound is good for colour changes, preventa-
tive machine maintenance and before manual cleaning. It has been designed for purging through hot runner systems and other equipment with tight clearances. The new hybrid technology is claimed to reach all stagnation areas, breaking down the colour contamination and removing it from the machine. No soaking time or temperature alterations are required, and there are none of the noxious fumes or odours associated with some chemical purging compounds. The range of applications for Dyna-Purge A has recently been expanded to include low temperature resins, such as TPE, TPO, TPR and TPV.
58 COMPOUNDING WORLD | April 2017
www.compoundingworld.com
currently regards streaking issues that come from trapped colour residue in hot runners and manifolds,” Lewis says. “TPOs also get a lot of attention at the moment and the many industries they feed into. Due to their flexible nature they are extremely hard to purge at times. Combinations of aggressive chemical purges with abrasive carriers seem to be getting more common.” An example of this type of combination can be seen
in Slide’s Klenz purging compound, which uses a polyolefin carrier combined with an expanding chemical that can effectively clean out hot runners and manifolds without clogging. Klenz also neutralises Delrin resin vapours, according to the company. Chem-Trend has added LusinClean 1100 to its range
of purging compounds. The company says LusinClean 1100 is a universal purge compound designed to improve colour and material changes for injection moulding machines. The company says early results show the new additive can reduce the number of parts required to make a complete switch in colour or material by up to 35% and adds that scrap reductions of more 90% have been achieved by some users during the initial evaluation. Lusin Clean 1100 is suitable for use with polyolefins and engineering plastics such as ABS, PS, PC, PC/ABS,
PHOTO: POLYTECHS
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