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WACKER at K 2016: To Launch Highly Transparent LSR for Lighting Technologies

Published on 2016-07-15. Author : SpecialChem

LSR for Optical Lens
MUNICH -- WACKER will present a new generation of highly transparent liquid silicone rubbers for lighting technologies at the 20th International Trade Fair for Plastics and Rubber K 2016.
  • LUMISIL® LR 7601 makes it possible to produce crystal-clear optical lenses and coupling elements for high heat and light exposure. 
  • New LSR is predominantly characterized by a significantly lower volatile content, which especially benefits processors. 
  • The vulcanizates only need to be thermally postcured for sensitive applications. Due to the low volatile content the postcuring time can be reduced for these applications, and the molded part suffers significantly less shrinkage. 
  • LUMISIL® LR 7601 is suitable for lenses, sensors and optical coupling elements in lighting technologies and can be processed cost effectively in large-scale injection molding processes. 

K 2016 will take place in Düsseldorf, Germany, from October 19 to 26, 2016.

Highly Transparent LSR for Optical Elements with Low Volatile Content

WACKER already hit the headlines at the K show three years ago with its highly transparent liquid silicone rubber for optical applications. Thanks to a special formulation concept, the company succeeded in formulating silicones in such a way that they can transmit visible light virtually unobstructed and withstand thermal stressing of up to 200°C even for long periods.

These benefits are also offered by the new liquid silicone rubber LUMISIL® LR 7601 LSR that WACKER will showcase at K 2016. Like its predecessor, the product offers outstanding transparency and heat resistance, making LUMISIL® LR 7601 superior to many other materials. Whereas polycarbonate and polymethyl methacrylate gradually yellow when exposed to heat, artificial or natural light, or ultraviolet radiation, the new silicone elastomer remains crystal clear, even under continuous exposure. The refractive index for all Shore hardness values is 1.41.

Highly Transparent LSR for Optical Elements
Highly Transparent LSR
for Optical Elements
However, LUMISIL® LR 7601 LSR offers yet another advantage. The silicone rubber has significantly lower volatile components than the previous product. These are largely removed during production, which in many cases virtually eliminates the need for thermal postcuring. If postcuring is still necessary, it can be substantially shortened. Moreover, linear shrinkage after postcuring is just half that of the previous product. Consequently, there are considerably fewer geometrical changes.

LUMISIL® LR 7601 LSR has a comparably low viscosity, which remains largely unchanged by shear forces. For this reason the grades – in contrast to conventional liquid silicones – can be injection molded very easily at low shear rates. They fulfill all material requirements that play a key role in the manufacture of optical elements.

Preferred applications for LUMISIL® LR 7601 are in lighting technology, for example, optical lenses. The resultant lens bodies can direct and shape a lamp’s light as is increasingly the case in modern vehicle headlamps. In adaptive front lighting systems, optical elements made of LUMISIL® LR 7601 can help to ensure that the road is optimally illuminated under any traffic conditions.

LUMISIL® LR 7601 LSR is extremely heat and radiation resistant. It is therefore ideal for applications with high-performance LEDs, which become very hot in continuous operation and emit very high-energy light. In combination with light emitting diodes, entirely new designs and housing structures are possible. Incidentally, this not only applies to car headlamps, but also to the development of energy-efficient and cost-effective lighting solutions, for example, in the general lighting field.

LUMISIL® LR 7601 covers four types with hardness values between 50 and 80 Shore A. The liquid silicone rubber can be readily processed by injection molding. This makes it possible to cost-effectively produce even delicately structured molded parts on a large scale. Lenses made from LUMISIL® LR 7601 LSR are resistant to aging and weathering, they are electrically insulating, water-repellent and low-temperature flexible.


WACKER is a globally active chemical company with some 17,000 employees and annual sales of around €5.3 billion (2015). WACKER has a global network of 25 production sites, 22 technical competence centers and 50 sales offices.

WACKER Silicones
Silicone fluids, emulsions, rubber and resins; silanes; pyrogenic silicas; thermoplastic silicone elastomers.

WACKER Polymers
Polyvinyl acetates and vinyl acetate copolymers in the form of dispersible polymer powders, dispersions, solid resins and solutions.

WACKER Biosolutions
Biotech products such as cyclodextrins, cysteine and biologics, as well as fine chemicals and PVAc solid resins.

WACKER Polysilicon
Polysilicon for the semiconductor and photovoltaic industries.

Hyperpure silicon wafers and monocrystals for semiconductor components.

Source: WACKER

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