SEKISUI S-LEC is among the leading producers of PVB interlayer films for automotive glazing. In this interview Lola van Ipenburg explains how rising requirements made on acoustics, thermal properties and smart functions are bringing changes to modern car glass design – and why multi-functional solutions in a single film play a pivotal role in this.
Which requirements are currently impacting car glass developments the most?
Lola van Ipenburg: At present, three aspects are particularly relevant: acoustics, solar and heat management as well as functional integration in laminated glass.
Acoustics are gaining increasing importance since panoramic roof surfaces are getting bigger and bigger and conventional sunblinds are disappearing. Compared to conventional vehicles with a panoramic sunroof area of around 0.5 square metres newer vehicles boast over two square metres of roof glazing – and correspondingly higher levels of noise ingress through the sunroof.
In wind tunnel tests performed with real vehicles SEKISUI S-LEC was able to prove that a panoramic sunroof fitted with S-LEC™ Sound Acoustic Film reduces noise ingress by up to 3 dB, equivalent to a 3.7% increase in the articulation index (measuring speech intelligibility) – compared to standard laminated sheet glass. In addition, marked improvements were confirmed not only in the front seats but also in the back seats.
Large sunroof expansion also considerably impact cabin temperature and energy consumption. For this reason, panoramic sunroofs are often fitted with the S-LEC™ Colour Film featuring light transmission degrees of typically 2% to 60% for various roof applications. By combining tint, sound insulation and solar protection the interlayer can become a comprehensive comfort system for the entire glazing – and all of this in a single film.
At the same time, the standard thickness of 0.76 mm remains unchanged without increasing system complexity. Likewise, switchable panoramic sunroofs are more widely used, especially on the European automotive market. Hence, glazing is becoming a truly multi-functional component.
Switchable glass is defined as glass that can change between transparent and opaque and/or translucent states through electrical or other light control mechanisms. S-LEC™ Opt Light offers optimised PVB film solutions for such smart glass technologies as PDLC, SPD, EC and GHLC. These solutions feature thinner tinting options, UV protection and optical clarity with little haze – thereby supporting both functional and design requirements made on modern vehicle architectures.
What is driving the increasing use of glass surfaces in vehicles, especially for panoramic sunroofs, and what are the limits to this?
Lola van Ipenburg: The rising use of glass is primarily being driven by interior design, perceived comfort and system simplification.
Panoramic sunroofs make for brighter and more open interiors – a feature that is increasingly appreciated by customers in various vehicle segments. At the same time, OEMs (Original Equipment Manufacturers) are reducing or eliminating mechanical sunblinds to attain more headroom while reducing weight and system complexity. This development results in higher functional requirements made on the glazing itself.
Limits are reached when acoustic, thermal, optical and weight-related requirements are considered in isolation. Large glass areas call for a carefully harmonised, system-oriented approach. Multi-functional interlayers offer a practical way to reconcile these competing requirements in one single, optimised structure.
How has electrification changed the expectations for auto glass?
Lola van Ipenburg: Electrification has sharpened the focus on noise control and energy efficiency.
In e-vehicles the absence of engine noise makes aerodynamic and road-induced noise more perceivable – especially through roof glazing. This is why S-LEC™ Sound Acoustic Film is increasingly deployed in panoramic roof systems to ensure the same acoustic comfort in all seating positions.
Light management is just as important for thermal reduction. The reduction of solar gains through the sunroof contributes to reducing air-conditioning needs and thereby helps vehicle range. S-LEC™ Colour Film solutions make for a dynamic light and solar protection control without adding mechanical systems or appreciable weight.
What should the glass industry prioritise to drive circular economy targets – despite the challenges associated with laminated glass?
Lola van Ipenburg: The focus should be on material development, long-term durability and functional consolidation. SEKISUI S-LEC offers a range of PVB interlayer film solutions that can make a positive contribution to the environmental performance. S-LEC™ Solar Control Film improves HVAC efficiency by blocking out infrared radiation from the sunlight, thereby reducing air-conditioning needs. S-LEC™ Sound Acoustic Film in combination with thinner laminated glass can reduce the total glazing weight while retaining or even improving its sound insulation performance – this increases the fuel efficiency of conventional vehicles and reduces the power consumption of e-vehicles.
Beyond this, the S-LEC™ Opt Light solutions are designed to protect switchable technologies against UV-induced degradation, thereby ensuring stable optical and functional performance over the vehicle’s entire lifecycle.
The combination of several functions – such as sound insulation, solar protection and switchable properties – in one single laminated structure also reduces the total material input and system complexity. From the European perspective, this integrated, engineering-driven approach is key to making true progress in more sustainable auto glass.
