02 September 2018

High light scattering silicon compounds (VMQ)

The era of LEDification and digitalization of illumination is completely redefining the way we perceive illumination systems. Abandoning stereotypes linked to traditional appliances and their installation (suspension, recessed, ceiling installed etc.) allows to see light as a form and create light landscapes with it. But light emitting diode (LED) technology is not only design, it is first of all technology, energy saving and reliability.

A LED is a semiconductor-based optoelectronic device. The constant development of this technology now allows emissions of over 300 lumens per watt for a single white light LED.

There is, however, a limit: LEDs are punctual elements by nature, they cover areas of a few square millimetres. Although stripe circuits or more complex assets can be created, the single units that compose the light source remain visible. Hence the necessity to encapsulate and cover sources with high light diffusivity materials (scattering) which can collect as much light as possible to diffuse it homogeneously in the environment. As much as LED light is considered cold, a certain quantity of heat is always emitted.

For this reason, high scattering materials must have a good temperature stability to avoid degradation and yellowing, phenomena that modify the emission spectrum of the lightning element. For a long time, thermoplastic elements or glasses have been the only choice. But the market requires flexible, impact resistant materials and with a higher chemical and temperature resistance.

Silicon rubber (VMQ) is a suitable elastomer for this application: among rubber materials silicon is surely the most interesting from the optical and thermic point of view. For these applications, MESGO has recently developer a new type of silicon compound with platinic reticulation and high light diffusion.

A regular translucent silicon reveals the light source, with an unaesthetic result (a).

The use of a white, opaque silicon compound, allows not only to hide LED sources completely, but also to attenuate the signal and to change its colour, which from white becomes yellow (b).

MESGO has developed a portfolio complete with high-scattering solutions and with different hardness for both moulding and extrusion. Through the study and control of the refraction index of the compound and of internal light diffusion, LEDs disappear and light, now perfectly white, is distributed homogeneously by the silicon profile (c).