New adhesive for automotive lighting

DELO has created a new adhesive for automotive lighting applications. DELO PHOTOBOND OB4189 is resistant to yellowing and, with its high aspect ratio, is especially suited to bonding microlens arrays, such as those found in headlights and projection systems.

These days, light is considered among the most essential elements of automotive design and differentiation. Microlens arrays are a key participant in these developments. They project LED light, which sits behind a very short focal length, delivering sharp images and individual geometries. Due to their low required installation depth, These systems are increasingly employed as optics in headlights and projection systems.

For increased efficiency, such microlenses are often constructed of optically pure polymers, in other words, adhesives. The microlens arrays are then fixed to a housing. With a high viscosity of 75,000mPa·s, the adhesive allows a high enough aspect ratio for bonding. The adhesive, therefore, keeps its shape after dispensing and does not flow, which is essential for bonding microlens arrays. It is also exceptionally resistant to yellowing, as shown by life cycle simulations of 500 hours at 140C. This is crucial for such optically demanding applications.

The modified acrylate is solvent-free and developed for a temperature application range of -40C to +120C. It has a compressive shear strength of 30MPa on polycarbonate and 25MPa on PMMA. It can be cured with UV light (365nm) and visible light (400nm). The typical exposure time at 400nm with a layer thickness of 100μm is five seconds. This allows high-precision active alignment processes for optical components and low cycle times in automated production.

"With DELO PHOTOBOND OB4189, we added a high-viscosity and extremely yellowing-resistant product to our portfolio of temperature and humidity-resistant active alignment adhesives that is precisely tailored to the requirements of microlens arrays," explains Christoph Appel, product manager – LED (Automotive) at DELO.

More information on adhesives for automotive lighting will be presented at an upcoming webinar on September 12. Experts will discuss how adhesives can replace soldering applications, how to align optical components precisely, and how more efficient manufacturing processes can be realised with different adhesive chemistries.