New transparent high-performance adhesive for modern headlight designs

DELO has developed a new transparent active alignment adhesive. DELO PHOTOBOND OB4210 is characterised by its yellowing stability at high temperatures and is extremely resistant to temperature and media. Manufacturers of automotive headlights can use it to realise optically sophisticated applications.

The UV-curing adhesive's transparent characteristics make it hardly distinguishable from the lens material. Its yellowing resistance is higher than similar products, retaining its transparency even after a 500-hour storage period at +140C. This is important for bonding increasingly powerful LED modules that generate more heat. The acrylic adhesive works with various materials found in a headlight, with stress-equalising effects and a wide range of elasticity. Thanks to its near-instantaneous UV curing, it is suitable for high-end applications such as the active alignment of lens systems and optics in matrix LEDs, MLA, or DLP headlamp systems.

As well as an application temperature range of -40C to +140C, the adhesive has a high compression shear strength of 35MPa on polycarbonate, a common optical material in the automotive lighting sector. Its low viscosity of 3,000mPa-s and subsequent good flowability also facilitate applications on larger surfaces. The exposure time needed to cure the adhesive can be reduced to 1.5 seconds at high UV intensities, providing process advantages in the form of higher cycle times in production.

DELO PHOTOBOND OB4210 manages two challenges for headlight manufacturers – miniaturisation and increased functionality – since headlights are becoming increasingly slim while at the same time becoming more powerful in the illumination of the vehicle's surroundings. Conventional bonding processes within headlights, such as screw connections, are reaching their limits, and adhesive solutions are increasingly in demand. However, to bond optics and lenses, they must fulfil stringent requirements. They should be stress-compensating and low-outgassing, withstand high temperatures and environmental influences, and remain highly transparent.

"With DELO PHOTOBOND OB4210, we are expanding our portfolio of temperature- and humidity-resistant adhesives for the automotive lighting industry using an extremely yellowing-resistant product that offers high strength. These properties are essential for optically demanding applications and are therefore perfect for modern headlight designs," says Christoph Appel, product manager, LED Automotive at DELO.

DELO PHOTOBOND OB4210 and other adhesive solutions for automotive lighting will be shown at the DVN conference in Shanghai on 4-5 December 2024.