Exaltec- a company jointly formed in 1998 by Bayer and GE (two largest manufacturers of Polycarbonate) to mainly develop a special coating to provide scratch resistance to Polycarbonate (PC) sheet so that it can be used for glazing of automobile, has finally seen the end of the tunnel. In June 2005, The U.S. Dept. of Transportation's National Highway Traffic Safety Administration (NHTSA) approved the Exaltec 900 material and coating system for all non-windshield glazing, provided that it meets all existing auto glazing specifications for laminated glass. NHTSA determined that no new regulations were necessary, PC glazing can be validated using existing specifications for laminated glass.

Polycarbonate has dominated the market for vehicle headlamp covers for 15 years and n ews from the auto industry is quite positive that Polycarbonate sheets will find application in automobile glazing shortly. PC glazing is being moulded into larger parts offering considerable weight saving and offer styling and design potential (distinctive 3D shapes) that glass cannot match. This emerging market holds good potential, but will be challenging as Polycarbonate (PC) car windows require specialized machinery, high-end processing capability, premium polymers, advanced coating technologies and innovative mould and runner designs. Glass auto windows are produced up to 1.5 or even 2 m 2 . With the latest technology, PC auto glazing can be molded up to 1.4 m 2 (around 15 ft 2 ), although some believe sizes up to 2 m 2 (21.5 ft 2 ) are expected very soon. Larger auto glazing can deliver weight savings up to 50% versus glass.
Unlike glass, PC glazing can have integral ribs or brackets to lock the parts onto the vehicle or support another feature. PC auto-glazing will also introduce design concepts such as a side window with the rear-view mirror mounted on it rather than on the door panel, vehicle roofs that wrap onto the rear of the vehicle, and moulded heating/defrosting elements and radio antennas into a PC window panel with in-mould films that have preprinted circuitry.
Recent developments in scratch-resistant coating systems have significantly broadened the PC glazing market in the U.S. Until last June, PC was limited in the U.S. to non-passenger areas of the vehicle, typically in back cargo areas of SUVs, though there are no such applications yet in the U.S. Regulations are less stringent in Europe and Asia.

Manufacturing of PC auto-glazing requires a special set of manufacturing techniques that go beyond the conventional in machinery, moulds, materials, and processing methods.
First, the new auto glazing parts are large - up to 1.4 m2 (around 15 ft2)�and they must to be moulded under low-stress conditions for optical quality and for retention of a hard coat. Residual stresses in the part negatively influence optical quality. High stress in the part can lead to haze or delamination of the coating. Injection-compression rather than conventional injection molding is the ideal process for making large parts with low stress. Machinery suppliers such as Battenfeld, Engel and Krauss Maffei have developed injection-compression processes to meet these low-pressure, low-stress requirements. Because large glazing panels are essentially thin-wall parts and must have parallel surfaces for good optical qualities, moulding machines must be able to maintain close parallelism of platens and molds�within 0.1 mm.
New tooling concepts have been developed by European firms and hot-runner designs have also affected by the new moulding criteria.
New PC materials had to be developed for good flow, higher optical clarity than conventional materials, and adhesion to a hard coat. Bayer MaterialScience and GE each developed advanced PC resins with part thickness averages 4 to 5 mm, and the flow-length to thickness ratio is around 300:1.
Simutaneously, advances were imperative in post-mould coating technology to deliver high resistance to abrasion, scratching and UV exposure/ weathering, as well as good light transmission and anti-reflective properties. This led to proprietary �wet-coat� formulations as well as a new wet-coat/plasma-coating technique.