DuPont’s new packaging film targets PE, aims to cut energy and waste

DuPont has released a new transparent packaging polymer designed to protect three-dimensional component surfaces while also conserving energy and reducing waste in a variety of packaging applications.

The process is the result of joint development work between DuPont, machinery producer Zappe Verpackungs, and machine and film producer Jura-Plast.

DuPont's Surlyn packaging resins are made from ethylene acid copolymers, in which the acid groups are partially neutralized with either zinc or sodium ions. The acid in the polymer gives polarity and reduces crystallinity.

"These interactions produce outstanding toughness, stiffness, and resistance," Barry Morris, DuPont Packaging senior scientist, told PlasticsToday.

Surlyn is available in a wide range of grades, each with a different balance of properties. DuPont tailors the properties of each grade by adjusting the acid content in the polymer, its molecular weight, the amount of neutralization and neutralization ion (zinc or sodium), and additive content.

Appliance manufacturer Miele was one of the first to use Surlyn at its plant in Warendorf, Germany, to prevent scratches on its high-gloss, thermoplastic bezel for washing machines as it make its way through the fully automated assembly line to retail. The tailored skin-packaging process helps prevent rejects and the corresponding raw-material waste.

With the combination of a modified adhesive resin from DuPont, adhesion between the component and the film is high enough for the fully assembled washing machine door, weighing around 5 kg, to be transported using vacuum grippers.

When working with the Zappe SKVA-5050 3D skin-packaging machine, the film exhibits good heat absorption that makes it stretchable after 10 seconds of heating, compared to about 15 seconds required for polyethylene, the release stated. This process can save energy and help achieve shorter cycle times.

Zappe Managing Director Ulrich Zappe stated Surlyn's chemical structure makes it melt-stable and tough even when heated, which is an important quality for three-dimensional components because it enables high draw ratios without the risk of the film tearing at the edges.

The formulation of the base layer results in no formation of air bubbles between the component surface and the film, which would otherwise spoil the high-quality appearance of the bezel, the company stated.

The skin-film itself, and its production residue, can be recycled in the PE waste stream. Surlyn weighs about one-third less than PE, which was the material used in an early development stage, according to a news release.

Yasmin Siddiqi, global development director for DuPont, said Surlyn answers three needs in the marketplace: sustainability, high performance, and low cost.

"With the current economic conditions, people are more and more concerned about costs," she said. "Here you get a very good value with a very low cost. "