New adhesive for automotive lighting 14 September 2023

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

These days, microlens arrays are key players in modern automotive design. They project LED light, which sits behind a very short focal length, providing sharp images and individual geometries. These systems are increasingly being used as optics in headlights and projection systems due to their low required installation depth.

With a high viscosity of 75,000 mPa·s, DELO PHOTOBOND OB4189 enables a high enough aspect ratio for the microlens bonding process. The adhesive thus retains its shape after dispensing and does not flow, which is important for bonding microlens arrays. It is also resistant to yellowing, which DELO states is shown by life cycle simulations of 500 hours at 140°C.

The modified acrylate is solvent-free and developed for a temperature application range of -40°C to +120°C. It has a compressive shear strength of 30 MPa on polycarbonate and 25 MPa on PMMA. It can be cured with 365Nm UV light and 400Nm visible light. The company explains that the typical exposure time at 400Nm with a layer thickness of 100 μm is 5 seconds. This enables 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.

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