Today Brampton Engineering makes lines to produce film with up to 11 layers. The company runs a nine-layer line in a high-bay area of its plant for customer trials and product development. By producing its own dies, winders, air rings and gauge control, Brampton controls the major components that must work together, under its Italycs controller, now in its fifth generation. The company also designs and assembles its gravimetric blenders.
Multilayer film goes into barrier packaging for a wide range of products, including meats, cheeses, frozen food, bakery items, vacuum pouches, cereal liners and shrink film. The film must give barriers to oxygen, moisture and aroma.
“It's high-end, high-performing film. That's where a majority of our business is, Hughes said.
Even so, a third of sales still come from three-layer and monolayer dies, he said. One emerging monolayer application is film to separate battery plates.
Officials of Brampton Engineering do not release sales figures or disclose how many film lines the company produces.
Brampton's key die design, the SCD, mounts each extruder at a different height along the die. Competitors bring all extruders to the die at the same level around the die, and use a spiral to bring the layers up through the entire die.
Brampton Engineering delivers the melt to the center mandrel at each level. That gives very good temperature isolation, as the different materials travel at the proper temperature for each one, until they finally come together at the end.
“The melt comes out of the screw, and we minimize the distance from the screw to the die. So all the layers don't have to travel up the height of the die,” Hughes said.
That feature is not important for conventional blown film.
“But if you get into nine or 11 layers, you're die's getting taller. And if you're all coming in at the bottom, you've got a longer flow path to the lip,” he said. “But all the materials are sharing the same temperature of the die.”
By isolating the temperatures of the different layer materials, and minimizing the residence time — also known in film as the “wetted path” — the Brampton die design gives better control and can allow the use of less material, Hughes said. Quality improves in complex film structures, he said, “because the temperatures are respected.”
Keeping the layer temperatures at the ideal level also cuts down on carbon buildup, so the time between die cleanings is longer, he said.
Brampton's AquaFrost technology — which blows the film bubble downward, the opposite of traditional blown film, with the collapsing system at the bottom — quickly cools the film with water, creating very clear, soft film with good mechanical properties and impact strength. AquaFrost goes into medical films, and is finding new uses in thermoforming, Hughes said.
“With AquaFrost, we can go to very thick films, competing with cast film, better than 200 microns thick. And we keep the clarity. We actually cool it so fast, it's performed extremely well in thermoforming in deep draw. They can get deeper draws with better material distribution,” Hughes said, citing trays for frozen foods that get microwaved. “In some cases they want that tray to be multi-layer with all the barrier performance. It's thermoformed, and in some cases we can make thick films on AquaFrost. And when they thermoform AquaFrost films, because of the crystalline structure, the morphology, they get better material distribution in deeper draws.”
Hughes said thick AquaFrost film fills out the corners, traditionally a problem area in thin thermoformed trays. Some of Brampton customers are targeting that market with AquaFrost, he said.
“So even the thermoforming people are interested, because if you have multilayer in that tray, you don't want to, when you're thermoforming, have the material thin out in the corners. You may fracture your barrier,” he said.
Hughes said Brampton Engineering has sold 17 AquaFrost lines since the company commercialized the technology at the 2001 K show.
“And more than half the clients are on their second or third line,” he said.
Brampton positions the blown-film AquaFrost against cast film, claiming it exhibits less crystallinity as water removes heat and cools the film faster than a chill roll can, gives higher output for the same width with lower scrap rate, and takes up less space.
Hughes said multilayer blown film lines are highly customized — but they also have to be more flexible today.
“Our conversations [with customers] start with, talk to me about your structures? It's not unusual to have 10 different structures on the table. … We're going to look at the whole variety of materials. And then the discussion is, now, the percentages of each one of those layers. Then we'll stand back and say, now this is the screw and the extruder specifications for your application,” he said.
Brampton engineers customize the melt channels for each layer in the die. They can demonstrate the ability to quickly flush out colors and materials from a given layer, enabling for short change-overs.
At the same time, the shorter runs, together with a shortage of highly skilled employees, means the controller has to be simple to use — not an easy task for a technology that controls super-thin layers, and is linked into the gauge control, cooling ring and the speed of haul off and winding. Hughes said the goal is an Italycs controller with one-touch to change recipes of a film structure.
Brampton Engineering's Prophecy predictive software uses a rheology library so users can see if their die is possible, in virtual terms.
Meanwhile, packaging continues to evolve. The fast growth of pouches for grocery items presents a challenge to blow molded and injection molded packaging. But Hughes said pouches present a big potential market for flexible film. Pouches are laminated, so they already use film bonded to layers of foil or paper.
“If we can come up with structures that are competitive and that eliminate downstream lamination, or downstream whatever, it gives us opportunities,” he said.
