Light emitting diode (LED) is a kind of electroluminescent solid device. With the continuous innovation of technology and the guidance of national policy, the whole LED product develops rapidly, and the LED packaging industry grows synchronously. Among the packaging materials, silicone packaging materials have been recognized by the industry because of their excellent performance, become the fastest developing and most valuable packaging materials, has shown a huge market value.

LED silicone packaging adhesive is a new type of high-end liquid silica gel, is also a kind of optical packaging called, can maintain high transparency in the visible 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 LED industry, the demand for LED packaging materials increases, among which LED silicone packaging adhesive has become a leader in LED packaging materials due to its excellent physical and chemical properties. With the aggravation of the energy crisis, the LED industry will continue to grow, so the market potential of LED packaging materials is huge. High power LED packaging materials require high light transmittance and refractive index of raw materials, phenyl silicone oil has become an important part of LED packaging materials. With the increase of phenyl mole fraction, the high temperature resistance, irradiation resistance and refractive index of silicone materials are improved, and the importance of phenyl silicone oil for LED packaging adhesive is increasing day by day.

LED packaging phenyl silicone oil mainly includes vinyl end methyl phenyl silicone oil and phenyl hydrogen-containing silicone oil. According to phenyl content, 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 45%). LED packaging adhesives for different purposes have different requirements for phenyl content. High-power LED packaging adhesives generally require higher phenyl content in order to achieve a high refractive index, so as to reduce the loss of light source energy.

Vinyl methyl phenyl silicone oil is a silicone oil with vinyl at the finger end, and the silicon atom on the main chain is connected with methyl and phenyl. According to the type of phenyl can be divided into methyl phenyl chain type, diphenyl chain type and mixed type (containing two phenyl chain). Phenyl hydrogen-containing silicone oil is divided into hydrogen-sealed phenyl silicone oil and hydrogen-containing silicone oil, the two uses are different. The former is mainly used as diluent or chain extender when added into the packaging adhesive, while the latter is mainly used as centralized crosslinking agent of the packaging adhesive, playing the role of crosslinking center. The preparation method of phenyl hydrogen-containing silicone oil is cationic polymerization, generally sulfuric acid. In order to reduce the process flow, the acid resin can also be used for catalytic polymerization, eliminating the step of neutralizing the catalyst, and the acid resin can be directly filtered out, and the acid resin can also be reused for many times.