Olefin capstock creates high-gloss polyethylene sheet without painting

A new high-clarity, high-gloss, non-stress-whitening olefin capstock material can be directly co-extruded onto polyethylene (PE), creating sheets with a painted plastics appearance for a cost-effective, decorative, and durable thermoformed product. A. Schulman Inc. (Akron, OH) says its Invision 3570 resin enhances the appearance and performance of high-molecular-weight polyethylene (HMWPE) at a lower cost and lighter weight than extrusion capped acrylonitrile butadiene styrene (ABS) and thermoplastic polyolefin (TPO) sheet, or acrylic and fluoroacrylic laminated sheet.

At left, a thermoformed part consisting of a monolayer HMWPE, with Invision 3570 cap resin technology for improved gloss and appearance on the right.

Dennis Smith, director of new business development at A. Schulman, told MPW that the product was driven by the market's desire for a higher gloss finish for UHMWPE, which, when thermoformed, typically has a dull or matte appearance. Sturdy and more economical than styrenic or TPO, UHMWPE is an appealing material for many applications, according to Smith. Invision 3570 is the newest in a series of capstock materials, with others targeting TPOs, as well as low-gloss grades.

In addition to the high-gloss and color performance, Invision 3570 targets markets ranging from heavy truck to marine, power sports, and recreational and agricultural vehicles. The materials have a minimum rating of 75 in the 60 degree Gardner Gloss test, placing them roughly four times higher than HMWPE alone. The material remains ductile to -40°C, and compared to ABS and TPO, Invision is approximately 10%-20% lighter.

Allowing OEMs to replace painted metals and plastics, Invision promotes a reduction in volatile organic compound (VOC) emissions, while also allowing recyclability and weight savings, which boosts fuel efficiency in vehicles. "[Lower VOCs] are a primary driver," for the new grade according to Smith. "With Invision, people can eliminate secondary operations like painting or coating." —Tony Deligio