New polycarbonate material blocks near infrared radiation

A new grade of polycarbonate (PC) boasting enhanced heat-absorbing performance while maintaining high visible light transmission properties is targeting automotive glazing applications. Developed by Sumika Polycarbonate Limited, grade SD Polyca HA2093M transmits 77.9% of visible light whereas its solar transmittance is only 45%, compared with 55.9% for an existing Sumika grade and 76.4% for a standard colored PC grade.

Latest polycarbonate grade from Sumitomo Chemical affiliate Sumika Polycarbonate shuts out IR irradiation, and in doing so has a cooling effect in vehicle interiors. The orange line indicates transmission in the visible (shown in green) and IR (shown in red) spectra. The dark blue line is for an existing heat absorbing grade, and the light blue line for a standard colored grade.

The grade can be extruded into sheet or injection-molded. Target applications include automotive glazing and carport roofing.

In another development, Sumika parent company Sumitomo Chemical has debuted a heat-resistant acrylic resin featuring higher melt flow, higher transparency, less yellowing over prolonged mold residence durations and under LED light source irradiation, and less formation of mold deposits compared with existing heat-resistant grades.

The new acrylic resin comes in two variants. Grade K610 has an MFR of 5 (230°C, 37.3 N), and can be molded at a tool temperature that is 10°C lower than conventional high heat grades, resulting in 10% faster cycle time and 4% less energy consumption. A 35% reduction in mold deposits is also reported. The yellowing index is reported to be 0.8.

Grade K612, meanwhile, has an MFR of 8, and can be molded at a tool temperature 15°C lower than normal, with 6% reduced energy consumption. This grade has particularly low moisture absorption.

Target applications for the new materials include thick lenses, headlamps, light guides, and in-vehicle display components.

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