Interest in polycarbonate (PC) automotive glazing is gaining momentum. Compared to the shape limitations of glass, PC glazing is versatile, lighter with high impact resistance. In this interview, Umamaheswaran Venkatakrishnan, who leads global marketing for SABIC’s automotive business, explains why PC glazing remains interesting to OEMs and for which window applications.
Polycarbonate (PC) glazing market penetration has been slow and limited. Laminated glass is now lighter and more formable. Further advances have been made to chemically toughen glass, too. So has the big push for polymer glazing gone away?
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The answer in brief is that we still very much feel the push for PC glazing. In fact, we appear to be at a tipping point with the state of technology readiness and increased number of validations among OEMs. The pressure to drop weight from vehicles means OEMs are still exploring options for glazing, and PC-based solutions are still top of mind.
By way of a longer answer, one needs to recognise that a number of factors can influence speed of technology adoption. In the case of PC glazing, the technology is ready to apply and several major automakers around the world have validated it. However, the supply chain infrastructure to support broader use will require more time to develop.
We at SABIC are supporting several Tiers in the industrialisation phase, knowing that many of our OEM customers would like to move towards PC glazing to help meet weight reduction targets, enhance styling and take full advantage of opportunities for functional integration. This includes new Tiers based in Asia actively adopting PC glazing technology.
Several Tier suppliers are licensees of our EXATEC plasma coating technology, which delivers the highest level of abrasion resistance and durability for PC glazing applications. So, supply chain capability is coming. This will be welcome news to many OEMs, especially those who have already validated the technology and are anxious to move forward with new window programmes.
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By GlobalDataToyota is among those OEMs actively exploring the technology. This is evident in its recent use of EXATEC plasma coating on the rear quarter window of its 86GRMN sports car, launched earlier this year. This is the industry’s first plasma-coated RQW. Up until this part, RQWs in PC glazing have used a wet-coat solution. This plasma coating provides the highest level of abrasion resistance and weathering performance.
As for other options mentioned, laminated and chemically strengthened glass have some significant limitations. They weigh more than PC glazing and the design possibilities are far less. The kind of styling and functional integration you can achieve with PC glazing is simply not feasible with these other options. This is particularly important when considering cost competitiveness as the functional integration possible with PC glazing can help lower overall costs. With PC glazing, you get weight savings plus additional value. With these other options, you get weight savings, though not as much as you can with PC glazing, but no additional value.
In terms of applications, where do you see the opportunities for PC glazing on passenger cars? And do you see it limited to aesthetic glazing, such as sunroofs?
We are focusing on rear quarter windows, roofs and backlites. RQWs and roofs are proven. Both the Fiat 500L and Citroen DS5 have RQWs in LEXAN glazing, which include integrated aerodynamic spoilers. The Corvette Stringray is using a hard-coated LEXAN resin for its targa top roof. This is actually the fourth generation of Corvettes to feature a rigid, see-through PC-based roof panel, which is 50 percent lighter than a glass solution. This LEXAN resin solution is enhanced through injection-compression-molding, a process that produces dimensionally-stable, low-stress parts.
The backlite represents a special opportunity as no other window part can take better advantage of all PC glazing can offer: from weight savings of up to 50 percent to enhanced styling and functional integration. We are excited to be actively working on backlite programmes with industry.
Opportunities abound well beyond aesthetics and styling. OEMs are driven mostly by weight savings, but not weight savings alone. They are looking for weight reduction and additional value.
It is true to say that glazing is playing an ever-increasing role in the overall design of a vehicle. OEMs are looking for ways to expand use of transparent areas and introduce new styling, and PC glazing is an exceptional fit there.
However, OEMs are attracted to the potential to cost-effectively integrate features in glazing that can give them other benefits: features that can reduce the number of components and materials associated with joining individual components to simplify assembly and reduce cost. Reducing the number of parts can result in secondary weight reduction. Greater shaping flexibility and integration in PC glazing designs can reduce aerodynamic drag and support enhanced fuel economy.
Another value attracting greater interest from OEMs is the thermal insulation properties of PC and the reduction in HVAC load that this makes possible for electrics and hybrids. The resulting energy savings can allow for extended range.
We understand that SABIC is developing PC car window technology with integrated lighting features. Could you tell us more and update us on the stage you are at?
Exploring these kinds of possibilities is exciting because we are combining our expertise in auto lighting with PC glazing, two areas where we have excelled in delivering solutions for OEMs.
We continue to explore new ways to use light on glazing surfaces. Today, we are focusing this work on our all-plastic tailgate, which includes a backlite in LEXAN resin. This backlite includes many integrated features, including rear lighting. We are working with OEMs today on taking this concept to the next development phase.
We will expand our work on glazing with integrated lighting in line with industry needs.
In what ways has your LEXAN been advanced in recent years?
We have optimised a LEXAN resin grade for production of PC glazing parts. This grade is LEXAN GLX resin, and it allows for improved processing, coating compatibility, cleanliness and UV stabilising for enhanced weathering.
PC glazing can be made up of two components over-moulded, a transparent area in LEXAN resin and a blackout over-moulded part in a mineral-filled grade of CYCOLOY resin, a PC/ABS material.
For this second shot material (blackout), we have worked to develop a resin with a focus on easy processing, 2K resin compatibility, 2K dimensional compatibility, optimal visual appearance and bonding with or without coating. In this case, the optimal resin is CYCOLOY XCM830.
In addition to resin development, we have focused on further development of our E900 plasma coat technology with superior weathering and scratch resistance versus wet coats. We support both coating technologies based on legislated requirements around glazing and OEMs’ varying needs around abrasion and weatherability performance.
For backlite applications, a defroster solution for 3D surfaces has also been a development focus of ours and several validations have been completed at different OEMs because of the significant interest in moving this application to PC for weight savings and more complex styling and design.
What were the notable advances you made for the PC solution fitted to the Ford Fusion concept?
In this case, we provided LEXAN glazing for the multi-material lightweight vehicle (MMLV) of Ford. The backlite part of this programme focused on weight reduction and the drop was significant: 35 percent or 7.4 pounds. And these weight savings were achieved even though the glazing was one millimetre thicker than the production version. One could say this was a notable proof point in the process of validating the weight reduction potential of PC glazing.
The window also featured use of EXATEC plasma coating for glass-like scratch resistance and weathering performance. As many know, this is a unique offering in the industry – which can greatly facilitate broader adoption of PC glazing.
How does polycarbonate compare to glass in terms of long term durability, particularly with regard to UV degradation? Does PC absorb UV energy? If so, to what extent does it change the material chemistry over time?
Protective coatings can offer the required performance for abrasion and weathering. This includes the use of additives to absorb UV radiation. UV absorbers in an exterior wet coated product protects both the PC and its interface with that coating or the underlying primer. The PC glazing system also limits transmitted UV radiation, which otherwise tends to degrade materials in the cabin interior. The UV absorber in the coating and in the PC also reduce UV exposure to the passengers.
We believe that PC suffers from a lower stiffness compared to glass. How does your solution deal with this problem?
The issue of stiffness does come into play and will need more development for larger, movable window parts. However, for significant weight reduction opportunities represented by fixed glazing parts like backlites, roofs and rear quarter windows, the solution is ready to apply and we have seen several examples now of roofs and rear quarter windows in production. Our next area of focus is the backlite.
What are the technical and market challenges that SABIC still face with PC glazing?
We have talked about further industrialisation of the supply chain. Progress is happening and we are doing our part to help share expertise and technology and educate the supply base.
We have also talked about the production readiness of rear quarter windows and roofs, with examples available today. One of the next steps is applying or translating this success to a mass-produced backlite. Programmes with OEMs are underway, which incorporates our focus on developing the needed defroster technology.
Finally, it is a change in how we design and think about window parts. Conventional glass is so limited in the value it can offer, the industry does not typically think about these surfaces of the vehicle from the beginning of the design process. With LEXAN resin and our PC glazing solutions, one needs to start thinking about these parts from the earliest stages. When you are thinking from the outset about what glazing can do in terms of styling, weight loss and integration, you are in the best possible position to take full advantage of PC glazing’s many benefits.
Umamaheswaran Venkatakrishnan leads global marketing for SABIC’s automotive business. His in-depth understanding of automotive plastics comes from more than 25 years of industry experience. In his current role, he oversees the development of SABIC’s portfolio of solutions and capabilities to enable the automotive industry to meet its most pressing challenges. He is a former board member of the Automotive Division of the Society of Plastics Engineers.
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