Milliken is already known as the world's leading supplier of clarifiers that enable polypropylene (PP), one of the most sustainable plastics on the market, to compete for applications demanding excellent optics, such as bottles and containers, but normally requiring more costly materials. Now, its new Millad NX8000 series not only sets a new benchmark for clarification, but also enables processors to make substantial improvements in their economics through reduced processing temperatures and shorter cycles.
The use of Millad NX8000 in packaging and other commercial applications has grown substantially in recent months, following its public unveiling at K 2007. "It's quickly becoming the industry standard," says Brian Burkhart, global market manager, Polypropylene Clarifiers. "No other additive puts clarity and gloss levels in polypropylene on par with other 'glass clear' polymers and even glass itself." It is equally applicable in products made by injection molding, extrusion-blow molding and injection-blow molding.
The tunable property of Millad NX8000 in random copolymer enables a wide spectrum of solutions ranging from "Ultimate Clarity"- step change in clarity and gloss in PP to levels comparable with "glass clear" polymers and glass - up to "Enhanced Quality" - significant improvements in transparency of PP combined with a wider processing window and improved productivity.
The principal purpose of Millad NX8000 is to enhance optics, but Burkhart says practice has shown that processors can also achieve considerable energy savings by using the additive. Numerous trials carried out by Milliken have proven that the additive can regularly yield cycle time reductions by as much as 15 percent, while the ability to process at lower temperatures can often cut energy consumption by 15-20 percent - and in some extreme cases by over 30 percent.
An injection molder normally processing PP at 240-260C can drop machine settings down to around 200C if they are using a compound containing Millad NX8000.
"Conventional clarifiers need a certain minimum level of energy input - which typically requires temperatures over 220C during processing - to ensure full solubility and hence performance in the final application," says Milliken development engineer Adam Newberry. "Millad NX8000 has much better solubility characteristics in PP, and these allow lower processing temperatures to be used." In some cases, temperatures can be reduced by as much as 30C.
"Savings will vary according to the equipment you are running, the process you use and the part you make," says Burkhart. "We encourage processors to do their own trials to see what savings they can achieve. But there is no doubt that whether they are using injection molding, injection-blow moulding or extrusion-blow molding, processors will gain important energy savings. We are making a considerable contribution to sustainability by enabling processors to cut their energy consumption and, by being able to use the lowest-density plastics they can, adopt an optimal lightweighting solution."
Milliken is now launching a version of the additive that is specifically aimed at extrusion-blow molding: Millad NX8500E. "With this new innovative grade, transparency in extrusion blow molding is no longer limited to PVC or PET," says Burkhart. Millad NX8500E will allow processors to optimize surface properties as well as bulk haze. It has been designed specifically to provide a step change in optical properties with standard Ziegler-Natta PP EBM resins. Bottles produced with Millad NX8500E exhibit excellent gloss and transparency and have a fresher look due to a low yellowness index. As with NX8000E, improvements are less dependent on processing temperatures than with existing clarifiers. Furthermore, no special mold finishes are required to achieve excellent aesthetics in bottles.