Scratch Resistant Resins for Protective Phone Cases
Protective phone cases using scratch resistant resins can be customized with personal photos or unique artwork thanks to the printing know-how of German company Artcover GmbH and the aesthetic durability of DuPont™ Crastin® PBT and DuPont™ Sorona® EP thermoplastic polymer.
Artcover GmbH (www.art-cover.eu) is a new concept for the personalization of electronic devices, such as mobile phones, that allows customers to have a picture of their choice printed on a protective, clip-on case. The company behind the highly-individualized customer service is German printing specialist scs printcom group GmbH of Dietzenbach, Germany.
"There is an ongoing trend toward mass-market products such as mobile phones and other handheld devices. We believe consumers are seeking new ways to customize these items," explains managing director Andreas Bach. "This led us to develop the printing technology and process, based on 3D dye sublimation, that would allow individual consumers—as well as companies or other groups and organizations—to simply submit their personal photos on the web and for us to print them in high definition on a protective cover." The quantity can vary from a single, one-off item—such as the picture of a favorite pet or a memorable vacation destination—to a series of identical images or motifs for marketing giveaways or branding campaigns.
The covers are molded by an external supplier to Artcover, engaged by the company to help select the best material for its printing needs. While polycarbonate was shown to address many of the mechanical demands of the application, it requires the application of an additional clear coating in order to allow penetration of the dye for a durable, high-end appearance. "Such a process is not only costly but also involves a low yield rate," recalls Mr. Bach, "so we looked for an alternative material that could be printed in high definition without the use of a coating, that would provide a scratch-resistant high gloss finish, and that would preferably also offer a 'green', environmental appeal."
In contrast to amorphous plastics, semi-crystalline plastics such as Crastin® PBT allow the sublimated dyes to penetrate into the material to a depth of between 0.2 and 0.3 mm. This makes the decoration highly resistant to wear, scratches and abrasion, resulting in a permanent image that remains sharp and stable.
As a result, and following comprehensive molding trials, Crastin® PBT was adopted as the material of choice for initial production of the covers available for the Apple iPhone® 3 and iPhone® 4/4S. A subsequent presentation by DuPont of the extremely durable, piano gloss finish possible with Sorona® EP thermoplastic polymer, which contains between 20% and 37% renewably-sourced material by weight, provides an additional environmental angle. "Initial trials with Sorona® PTT have been very successful and we are planning to switch production to the renewably-sourced material in the near future," confirms Mr. Bach.