Methyl Phenyl Ethenyl Silicone Resin IOTA 208 is a high-purity, specialty silicone resin engineered for superior performance in advanced manufacturing processes. Synthesized from phenyl monomers and subjected to a specialized post-treatment, this resin is characterized by its high reactivity and exceptional functional properties, making it a reliable and critical raw material for formulating high-temperature resistant liquid addition-cure silicone rubbers and high-refractive-index LED encapsulants.

Key Characteristics and Advantages

The outstanding value of IOTA 208 stems from its precise molecular design, which incorporates two key functional groups: phenyl and ethenyl (vinyl).

• High Reactivity: The resin features a remarkably high Ethenyl (Vi) content, typically between 3.0-3.4%. This high concentration of reactive vinyl groups (-CH=CH₂) acts as numerous cross-linking sites. In the presence of a platinum catalyst, these sites readily undergo an addition reaction with Si-H groups from cross-linkers (e.g., hydrogen-containing silicones). This reaction is highly efficient, proceeding at lower temperatures with minimal catalyst usage, and is complete without producing any by-products, resulting in odorless, fully cured products.

• Excellent Thermal Stability: The incorporation of bulky phenyl groups into the silicone backbone provides significant molecular rigidity and enhances the thermal-oxidative stability of the cured material. Products formulated with IOTA 208 can maintain their structural integrity and elastomeric properties even when exposed to prolonged high-temperature environments exceeding 200°C.

• High Refractive Index: The phenyl content also elevates the resin's refractive index (nD) to 1.54. This optical property is crucial for LED packaging applications, as it reduces the light loss at the interface between the LED chip and the encapsulant, thereby significantly improving light extraction efficiency and overall lumen output.

Primary Applications

• LED Encapsulation: IOTA 208 is an ideal base polymer for formulating clear, high-refractive-index encapsulation gels and resins for high-power LEDs, COB modules, and LED filaments. It ensures excellent light output, long-term reliability, and resistance to yellowing under heat and UV exposure.

• High-Temperature Silicone Rubber: It serves as a fundamental component for manufacturing addition-cure liquid silicone rubbers (LSR) that require exceptional resistance to extreme heat. These rubbers are used to create seals, gaskets, insulators, and protective components in demanding industries such as automotive (engine compartments), aerospace, and industrial lighting.

Technical Specifications Summary

• Appearance: Colorless transparent liquid

• Refractive Index (nD): 1.54

• Solid Content: ≥ 96%

• Ethenyl (Vi) Content: 3.0 - 3.4%

• Viscosity (25°C): 38,000 - 53,000 mPa·s

In conclusion, Methyl Phenyl Ethenyl Silicone Resin IOTA 208 is a premium functional material that successfully combines high reactivity, thermal resilience, and optical clarity. It is an indispensable enabling material for innovators and manufacturers in the optoelectronics and high-performance elastomer industries.