Advantages and Applications of End Vinyl Silicone Oil
In recent years, the addition of ethylene based silicone oil to silicone rubber has attracted much attention due to its characteristics of no by-products during vulcanization, minimal shrinkage rate, deep vulcanization ability, and easy preparation of high-purity, high transparency, and flame-retardant products. This material has been widely used in various fields such as LED packaging, electronic component encapsulation, power and electrical industry, and liquid silicone rubber addition.
▲ Reaction mechanism and key raw materials
The sulfurization mechanism involves the hydrosilylation reaction between vinyl containing polydimethylsiloxane and compounds containing hydrosilylation groups under the action of catalysts, with terminal vinyl polydimethylsiloxane being the key raw material. When preparing addition molded silicone rubber, end vinyl polydimethylsiloxane (Vi PDMS) is a key raw material, usually synthesized through anionic or cationic ring opening polymerization using octamethylcyclotetrasiloxane and divinyltetramethyldisiloxane (also known as vinyl double head) as starting materials.
▲ Selection and Influence of Catalysts
The catalyst includes potassium hydroxide alkali gel and tetramethylammonium hydroxide. Potassium hydroxide alkali gel has the advantages of low dosage and easy filtration, while the continuous solid acid method reduces residue and improves product stability. The commonly used catalysts for anionic ring opening polymerization reactions include hydroxides or quaternary ammonium hydroxides of alkali metals K, Na, and Li, while tetramethylammonium hydroxide [(CH3) 4NOH] is widely used as a catalyst in China. Although (CH3) 4NOH has high catalytic activity and is easily removed by heating after reaction, a small amount of decomposition products will remain in the product, which to some extent affects the quality of the product. In contrast, using potassium hydroxide alkali gel as a catalyst has the advantages of low dosage, easy neutralization, simple filtration, and pure product. In addition, the new process method adopted by Strong Chemical, the solid acid continuous method, not only has less residue, but also has multiple advantages such as high flash point and low volatility.