Teijin develops new hard-coating technology for automotive plastics glazing
10 March 2017
Teijin Limited has developed a new hard-coating technology that can be applied evenly on large or complex-shaped automotive windows made of resin to achieve the same level of abrasion resistance as glass windows and double the weather resistance of conventional plastics glazing.
Teijin initially will produce small-lot samples of actual windows for selected car models at a pilot plant in Matsuyama. Going forward, it will gradually verify production technologies for the manufacture of a wider range of windows on a mass-production basis, aiming at an early launch of full-scale commercial manufacturing operations.
To further reduce automobile weights, automakers seek to use lightweight but highly abrasion-resistant back and side windows made of resin. Conventional polycarbonate (PC) plastics glazing, which are less abrasion-resistant than glass, can be scratched even by just raising or lowering them or by operating the windshield wipers.
According to Japanese automobile safety standards, plastics glazing in car models released from July 2017 must offer enhanced abrasion resistance. The conventional wet method used for hard coating, however, does not meet the required level of resistance. Furthermore, plastics glazing in new cars also will be required to be sufficiently weather resistant to prevent yellowing after long-term exposure to sunlight.
Although there is a technology for adding plasma enhanced chemical vapor deposition (plasma CVD) layer to enhance the abrasion and weather resistance of wet coated PC to the level of glass, the size of the window is restricted to around 0.3 m2, and it is also hard to apply plasma CVD to complex curved surfaces. Consequently, this technology does not offer a practical solution for plastics glazing under the new auto standards.
In response, Teijin collaborated with Tsukishima Kikai Co., Ltd. to develop a plasma CVD pilot plant that is capable of treating large and three-dimensional molded resin products with a uniform coating of plasma CVD. Actual-size plastics glazing exceeding one m², including those with complex curves for back windows, are being treated at the pilot plant.
The plasma CVD method achieves abrasion resistance on the level as glass, satisfying not only the new Japanese standards but also those of the US and EU.
The new hard-coating technology firmly applies a plasma CVD layer to the wet hard-coat layer, thereby preventing oxygen or water vapor from penetrating and subsequently degrading the underlying wet hard-coat layer. Since the wet hard-coat layer absorbs the ultraviolet rays which cause degradation of resin, the duration until discoloration or degradation is elongated to the double of only wet hard-coat by combination with CVD method.
Amid the trend toward lighter auto bodies in the face of ever-tightening environmental regulations, Teijin is leveraging strong, lightweight, high-performance materials and their hybrids to expand and develop its automotive business as a key strategy for medium- to long-term corporate growth.
In addition to development of the advanced plastics glazing announced today, Teijin is now collaborating with Continental Structural Plastics Holdings Corporation in North America, a leading automotive composite supplier that became a wholly owned subsidiary of Teijin in January 2017.
So which safety standards does this meet (e.g. AS1, AS2?).
Since the CVD layer is only on one side (so far), it would seem to be unsuited to lift windows, due to scratching on the unhardened face.
For some context, aircraft glazing has been polymer for pretty much ever (Perspex/Plexiglas, and who knows what today). I could see polymer glazing happening in cars, but the Teijin press release was focused on abrasion, and was silent on economics and regs.
Posted by: Bob Niland | 10 March 2017 at 06:29 PM