Plastics Look, Feel, And Act Their Best

The dictionary may tell you that "aesthetics" is all about appearances, but engineers who work with plastic parts know otherwise. Oftentimes you cannot separate aesthetic and functional requirements. Some colorants, for example, can reduce a part's impact strength. Or a rib needed for structural reasons may read through on a show surface. This interplay between looks and performance may soon operate on an entirely different level. At a recent seminar, GE Plastics Aesthetics Industry Manager, Sam Lugiano discussed new aesthetic technologies with positive engineering implications, including improvements to molded-in color for the elimination of paint and nanotechnology enhancements of part surfaces.

Functional Surfaces

If the future of plastic-part aesthetics involves functional surfaces, the future may be starting right now. Lugiano says there's a growing interest in parts whose surfaces combine aesthetics with electrical, anti-microbial, self-cleaning, self-repairing, or sensing properties. Nanotechnology may make these surface qualities a commercial reality over the next few years, Lugiano predicts. And he goes on to point to two patented nanotechnology developments that are just ready to leave the the company's corporate lab. One of them renders a variety of plastic surfaces superhydrophobic—making those surfaces, in essence, self-cleaning. "It's the whole Lotus effect," Lugiano says, noting that there could be hundreds of uses for the technology in medical, automotive, appliance, and other applications. He won't say publicly whether the superhydrophobic technology is applied as a coating or built into the resin or both. The other nanotech development is plastics-friendly dye that acts a moisture sensor. Based on a gold salt, the dye turns a copper color when exposed to moisture. In the absence of moisture, it goes back to its original color. Lugiano says GE is seeking development partners for both the superhydrophobic and sensor technologies. Send him an email at samuel.lugiano@ge.com for more information. For a video showing the superhydrophobic sample in action, go tohttp://rbi.ims.ca/4399-554.

Engineered Fillers

Metallic flake in molded parts has become a popular aesthetic choice for everything from appliances to consumer electronics. But these flake-filled parts tend to suffer from visible flow lines—areas in which the flakes take on a flat orientation relative to the surface of the part in response to flow conditions. As part of its of its growing portfolio of visual effects for plastics, GE has developed Engineered Fillers (EF) that can reduce the appearance of flow lines by encapsulating the oblong flakes in polymer spheres that prevent them the orienting flat. Lugiano says the initial expectation for this technology was that it would completely eliminate flow lines, "but after a year and a half of testing we found that it doesn't work for every part." For large parts, such as computer displays, the benefits of the technology don't seem to outweigh the costs. "Painting may still be the most cost effective option here," Lugiano says. But for small parts, such as cell phones and other consumer electronic housings, EF technology can render parts flow-line free or nearly so, making molded-in metallic colors a viable alternative to paint. EF technology is currently limited to metallic fillers, but Lugiano says that a next generation of encapsulated mica and pearlescent fillers is in the works and should be ready some-time next year. For more information about the cost benefits of molded-in color versus painting, try GE's on-line paint-cost calculator at http://rbi.ims.ca/4399-552.

New Surface for Noryl

One of GE's newest resin technologies imparts a low-gloss surface to parts made from the company's Noryl polyphenylene oxide—and does so without tooling modifications. This matte look alone may be appealing in some applications, but there's more to the material than appearances. Lugiano notes that the matte finish also has some desirable tactile attributes. "It has a soft, silky feel," not found on a glossier surface. What's more the material naturally resists fingerprints and mild scratches—of the kind caused by a fingernail rather than a tabor test. This new resin just became commercial last month and is currently available in about a half dozen color choices. Lugiano says the same technology may also be applied to other plastics over the coming year. For more information on Noryl, go to http://rbi.ims.ca/4399-553.