Light-emitting diode (LED) is an electroluminescent solid device. With the continuous innovation of technology and the guidance of national policies, the entire LED product has developed rapidly, and the LED packaging industry has grown simultaneously. Among packaging materials, silicone packaging materials have been recognized by the industry due to their excellent performance and have become the fastest growing and most valuable packaging materials, showing huge market value.

LED silicone encapsulant is a new type of high-end liquid silica gel, also known as optical encapsulation. It can maintain high transparency in the visible light region and has a high absorption rate of ultraviolet rays, which can improve the light output rate and use of lighting devices. life. In recent years, due to the rapid development of the LED industry, the demand for LED packaging materials has increased. Among them, LED silicone packaging glue has become the leader among LED packaging materials due to its excellent physical and chemical properties. As the energy crisis worsens, the LED industry will maintain sustained growth. Therefore, the market potential for LED packaging materials is huge. High-power LED packaging materials require their raw materials to have high light transmittance and refractive index, and phenyl silicone oil has become an important component of LED packaging glue raw materials. As the phenyl mole fraction increases, the high temperature resistance, radiation resistance and refractive index of silicone materials are improved, and the importance of phenyl silicone oil for LED encapsulants is increasing.

Phenyl silicone oil for LED packaging mainly includes vinyl-terminated methylphenyl silicone oil and phenyl hydrogenated silicone oil. Phenyl silicone oil can be divided into: low phenyl silicone oil (phenyl mole fraction 5% - 10%); medium phenyl silicone oil (phenyl mole fraction 25%); high phenyl silicone oil (phenyl mole fraction 25%) 45%). Different uses of LED encapsulants have different requirements for phenyl content. High-power LED encapsulants generally require higher phenyl content in order to achieve a high refractive index, thereby reducing the loss of light source energy.

Vinyl-terminated methylphenyl silicone oil refers to silicone oil with vinyl end groups and methyl and phenyl groups connected to the silicon atoms on the main chain. According to the type of phenyl group, it can be divided into methylphenyl chain unit type, diphenyl chain unit type and mixed type (containing two kinds of phenyl chain units at the same time). Phenyl hydrogen-containing silicone oil is divided into hydrogen-terminated phenyl silicone oil and side-containing hydrogen phenyl silicone oil, both of which have different uses. The former is mainly used as a diluent or chain extender when added to the encapsulant, while the latter is mainly used as a centralized cross-linking agent for the encapsulant and serves as a cross-linking center. The preparation method of phenyl hydrogen-containing silicone oil adopts cationic polymerization method, generally using sulfuric acid. In order to reduce the process flow, acidic resin can also be used for catalytic polymerization, eliminating the step of neutralizing the catalyst, directly filtering out the acidic resin, and the acidic resin can be reused multiple times.