As space and weight constraints drive more compact, sleeker forward lighting components, automotive suppliers seek materials that can meet the challenges posed by these new designs, including higher temperatures from proximity to bulbs and thinner-wall parts for reduced mass.

Addressing this demand, GE Plastics’ new Lexan Xtreme Heat (XHT) resin portfolio, one of the company’s Signature Surfaces solutions, now offers automotive lighting designers new material choices for their most demanding applications. Lexan XHT resins deliver excellent resistance to deformation and colour shift under high-heat conditions, and surpass many competitive materials such as thermosets in recyclability potential, density, and flow characteristics. Further, when used for bezels and reflectors, new Lexan XHT resins enable direct metallisation, which eliminates the costs and environmental impact from pre-coating the part with paint or lacquer.
“These innovative materials complement GE’s existing offerings, giving designers exciting new choices,” said Jim Wilson, global market director for GE Plastics’ Automotive Lighting division. “Lexan Xtreme Heat resins not only address today’s tough auto lighting challenges, they also provide an environmentally responsible alternative to materials that can’t be recycled or require pre-coating before metallisation. This further supports GE’s ecomagination initiative to create innovative new materials solutions that benefit our customers, the environment, and society at large.”
To help designers create thinner-walled lighting components that can reduce size and weight, Lexan XHT resin grades offer improved flow characteristics for injection moulding. Enhanced flow helps decrease melt temperatures and cooling requirements, decreasing cycle times by as much as 10 per cent. In new designs, the GE resins offer an opportunity to decrease wall thickness and material costs.
Compared with competitive materials, GE’s Lexan XHT resins have a lower specific gravity that can help auto suppliers reduce part weight for better fuel efficiency.
The GE materials have a specific gravity of 1.22 vs 1.9 or higher for many thermoset resins. Even competitive thermoplastic materials used in lighting applications, such as polyethersulfone (PES), are as much as 12 per cent denser than Lexan XHT resins. GE Plastics’ new Signature Surfaces solutions includes the company’s recently introduced LiteDesign web-based toolbox of advanced predictive technologies and other online services to help automotive lighting designers streamline the design optimisation and material selection process for greater time and cost savings.
Lexan is a registered trademark for General Electric Company’s brand of highly-durable polycarbonate resin thermoplastic intended to replace glass where strength justifies its cost. It is made up of chains of Bisphenol A  alternating with carbonyl chloride,  also known as phosgene.
Lexan was discovered in 1953 by GE chemist Dr Daniel Fox, while working on a wire coating. Dr Hermann Schnell of Bayer in Germany applied for a US patent on a virtually identical molecule in the same year that GE filed for a patent, 1955, but Dr Fox is generally credited with the discovery. Lexan is similar to polymethyl methacrylate (plexiglass/lucite/perspex) – commonly described as acrylic – but is far more durable, often to the point of being described as bullet-proof (depending on the thickness of the sample and the type of weapon used). Lexan is typically used in the aerospace industry for items such as aircraft canopies, windscreens and other windows, but can often be found in household items such as bottles, compact discs and DVDs. It is also one of the most common products to make bullet-resistant glass.
Lexan is manufactured at several GE plants around the world, the largest being in Mount Vernon, Indiana; Cartagena, Spain; and Bergen op Zoom, The Netherlands.