LED silicone encapsulant is a new type of high-end liquid silicone, and it is also a kind of optical packaging. It can maintain high transparency in the visible light region, has a high absorption rate for ultraviolet rays, and 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 in LED packaging materials due to its excellent physical and chemical properties. With the aggravation of the energy crisis, the LED industry will maintain continuous growth. Therefore, the market potential of LED packaging materials is huge. High-power LED packaging materials require high transmittance and refractive index of their raw materials, and phenyl silicone oil has become an important part of LED packaging materials. With the increase of phenyl molar fraction, the high temperature resistance, radiation resistance and refractive index of silicone materials have all improved, and the importance of phenyl silicone oil for LED encapsulant is increasing.

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

Vinyl-terminated methyl phenyl silicone oil refers to the silicone oil whose end group contains vinyl group and the silicon atom on the main chain is connected with methyl group and phenyl group. According to the type of phenyl group, it can be divided into methyl phenyl chain type, diphenyl chain type and mixed type (contains two kinds of phenyl chains at the same time). Phenyl hydrogen-containing silicone oil is divided into hydrogen-terminated phenyl silicone oil and side-hydrogen-containing phenyl silicone oil, which have different uses. The former is added to the encapsulant and is mainly used as a diluent or chain extender, while the latter is mainly used as a concentrated cross-linking agent of the encapsulant, which acts 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, the acid resin can also be used for catalytic polymerization, the step of neutralizing the catalyst is omitted, the acid resin is directly filtered, and the acid resin can be reused many times.