Light-emitting diode (LED) is a kind of electroluminescent solid device, with the continuous innovation of technology, coupled with the guidance of national policies, the rapid development of the entire LED product, LED packaging industry with synchronous growth. Among the packaging materials, silicone packaging materials have been recognized by the industry because of their excellent performance, and have become the fastest growing and most valuable packaging materials, which have shown huge market value.

LED silicone packaging adhesive is a new type of high-end liquid silicone, is also a kind of optical packaging called, can maintain high transparency in the visible light region, has a high absorption rate of ultraviolet light, can improve the light output rate and service life of lighting devices.

In recent years, due to the rapid development of the LED industry, the demand for LED packaging materials has increased, among which LED silicone packaging adhesives have become the leader in LED packaging materials with their 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 their raw materials to have high transmittance and refractive index, and phenyl silicone oil has become an important part of LED packaging materials. With the increase of phenyl mole fraction, the high temperature resistance, radiation resistance and refractive index of silicone materials have been improved, and the importance of phenyl silicone oil for LED packaging has been increasing.

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

Vinyl-capped methyl phenyl silicone oil is a silicone oil with vinyl in the finger group and methyl and phenyl in the main chain. According to the type of phenyl, it can be divided into methyl phenyl chain link type, diphenyl chain link type and mixed type (containing two phenyl chain links at the same time). Phenyl-hydrogen-containing silicone oil is divided into hydrogen-sealed phenyl silicone oil and hydrogen-containing phenyl silicone oil. The former is mainly used as a diluent or chain extender when added to the packaging adhesive, while the latter is mainly used as a concentrated crosslinking agent of the packaging adhesive and plays the role of a crosslinking center. The preparation method of phenyl hydrogen-containing silicone oil is cationic polymerization, 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 also be reused many times.

Vinyl-capped methyl phenyl silicone oil and phenyl hydrogen-containing silicone oil are the basic raw materials of high refractive index LED packaging adhesives. With the rapid development of LED industry, LED packaging industry has unlimited potential, and the demand for phenyl silicone oil is huge. In recent years, with the further improvement of domestic production technology of phenyl monomers and intermediates, the research of such products has made certain progress, but there is still a certain gap compared with foreign products, which needs to be improved. At present, the preparation technology and market of high-refractive index LED packaging adhesive are monopolized by foreign silicone companies, and phenyl materials are the key to the development and the focus of urgent research.