Liquid colorants now can be used in HDPE blow molding without the usual problems of screw slippage. They also permit use levels up to five times greater than previously possible, allowing more intense colors in both injection and blow molding, according to the Rite Systems unit of Clariant Masterbatches, W. Chicago, Ill. A new carrier not based on mineral oil or polyethylene glycol is tailored for HDPE. It is said to eliminate screw slippage, which has made liquid colors rarely used in HDPE extrusion blow molding, according to Clariant. Container tests reportedly show that the new liquids have no adverse effect on topload strength, and containers easily pass 7-ft drop tests.
What’s more, the new liquids are said to have a self-cleaning effect that allowed a change from black to white bottles in just 30 min during a production trial—something not possible even with solid masterbatches.
Liquid colors in HDPE have been limited mainly to injection molding, but Clariant’s new carrier extends application to blow molding and reportedly allows use of up to 2.5% colorant without affecting screw performance, vs. a previous limit of 0.5%. Clariant’s next goal is an improved liquid carrier for PP blow molding.
As a result of its acquisition of Rite Systems, Inc. last year, Clariant now also supplies liquid-color pumps. A brand-new feature on those pumps at the time of the acquisition was Bluetooth wireless connectivity, so that a PDA can monitor and control up to 10 pumps.
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