Polycarbonate Is Clearly Lighter

Mass reduction is an absolute must when it comes to electric vehicles for the simple reason that if there is less mass to be moved, then the motor doesn’t have to work as hard as it otherwise might, which means less energy is consumed.

One of the areas where there has been a material substitution for purposes of cutting weight is in the glazing. As in the window glass.

Tommykaira ZZ

While side glass has been replaced with a polycarbonate (PC) material in many cases, replacing the windshield hasn’t happened in the U.S. or Japan due to regulatory issues. Part of the problem is that the PC material hasn’t been shown to be sufficiently abrasion resistant and the last thing you want in any car—EV or traditional—is a cloudy windshield.

But Japanese material company Teijin Ltd. has announced that it has developed a PC resin-based windshield that will be deployed on the Tommykaira ZZ electric vehicle produced by GLM Co., Ltd. (a spin-off from Kyoto University).

The material meets the new Japanese standards (new as in going into effect this month). This is a result of Teijin’s development this past March of a new plasma-enhanced chemical vapor deposition process for coating the PC.

The window is thicker around its perimeter so that a traditional A-pillar isn’t required. (Although they claim that they’ve “managed to eliminate the need for the A-pillar,” it surely appears as though there is a support structure on either side.)

With a traditional glass surround (and full A-pillars)

The frameless and truncated A-pillar approach with thicker PC on the periphery

Still, they say that compared to a conventional glass windshield and A-pillars arrangement, the setup for the Tommykaira ZZ is 36 percent lighter.

An additional advantage to the PC window is that it offers 200 times the impact resistance of glass.

Teijin plans to market the new material in both the U.S. and the EU.