Itasca, Ill. — Coinjection molding is used for preforms and packaging, but not so much in closures. Russell Bennett of Milacron LLC wants to change that.
The coinjection process sandwiches two outer layers of plastic around one inner layer. Milacron got into coinjection molding in 2014 when the machinery manufacturer bought Kortec Inc. in Rowley, Mass. Bennett is director of sales and marketing for coinjection systems.
Speaking at the Plastics Caps & Closures Conference, Bennett said coinjection molding can add a barrier layer inside, for longer shelf life, or can use a core with a different color that shows through the cap's outer wall. One customer is looking at clear outer layer and an interior with a sparkling, glittery look, giving the package a high-end look.
“We can go up to 50 percent of the part weight with recycled material in the core,” he said.
Bennett said that Kortec has more than 100 coinjection systems in operation. The company can do turnkey systems on new injection presses, and now under Milacron ownership, can upgrade existing injection presses for coinjection.
“We are machine agnostic,” Bennett said. “If you have one of the other guy's machines in your facility and you want to upgrade it to be a coinjection unit, we can do that.”
The Milacron Kortec coinjection systems also can easily allow color changes, or run variegated colors that give an attractive finish when using two colors, Bennett said. He said a few customers in the PET bottle sector are going to be showing products with the variegated look in the next few months.