An illuminating concept

Louise Smyth

Julia Vorley details how an LED potting problem in India was resolved in less than 24 hours via the use of an innovative resin product 

The Indian LED lighting systems specialist Rockforest Technologies was recently contracted to supply LED strip lighting units for luminaires destined for a shopping complex in Bangalore, India.

The specification stipulated that the LED lighting strips  should provide a ‘neutral white’ (4,000K) colour and that the LEDs in the luminaires be potted to protect them from adverse environmental conditions.

Electrolube India conducted some initial trials, potting the strip luminaires to a specified depth of 5.5mm using UR5634, a semi-rigid, optically clear polyurethane resin that is widely used for encapsulating LED lighting systems.

With excellent protective and decorative properties, the UR5634 resin is also highly UV-resistant, making it especially useful as an encapsulant for applications exposed to direct sunlight.

In this particular application the resin caused a colour shift from the LED array, from the specified 4,000K (neutral white) to ‘cool white’ (6,500K).

Rockforest was under considerable pressure to solve this problem as the 4,000K colour was a non-negotiable specification; moreover, the customer requested that a new reference sample, which met the 4,000K colour specification, be made available for re-testing in just 24 hours.

Electrolube’s technical support team needed to act quickly to help Rockforest meet this very tight deadline and suggested two different approaches to consider to solve the problem.

The first of these was a recommendation that the team used an LED that provided a colour temperature below the specified colour temperature - in this case, one operating in the 2,500K to the 3,000K range.

By potting these with the UR5634 resin to the specified 5.5mm depth, it could potentially bring the light back to the desired colour.

The second option was that Rockforest assessed the amount and type of resin it was using for this project to see if a thinner layer of resin over the top of the LED array would reduce the colour shift effect.

Hazy resin solution

Ultimately, Rockforest opted to use UR5635, Electrolube’s semi-rigid polyurethane resin, formulated with a ‘hazy/cloudy’ appearance, ideal for dispersing light.

The diffused light produced by this resin meant that an additional diffuser medium was no longer necessary, allowing the customer to achieve the required aesthetic appearance and, through trials with various resin potting depths, the correct colour temperature.

During these trials, the rapid gel time of UR5635 caused a complication but Electrolube solved this problem by suggesting a staged potting procedure.

UR5635 exhibits outstanding water and weather resistance, as well as excellent resistance to acids and alkalis, making it suitable for a wide range of environments and an extremely durable potting compound. It is also resistant to UV light, making it especially useful as an outdoor LED encapsulant or for use in other applications where it may be exposed to direct sunlight.

Julia Vorley is with Electrolube.   

Rockforest Technologies sought out Electrolube India

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