Vinyl silicone oil is a type of modified organosilicon polymer with polydimethylsiloxane as the main chain and vinyl (-CH=CH₂) reactive groups introduced at the end or side of the molecular chain. As a core intermediate in the organosilicon industry, its performance is closely related to the molecular structure, vinyl content and distribution. It combines the low surface tension, high and low temperature resistance, weather resistance of organosilicon with the high reactivity of vinyl, and is a key raw material for preparing addition-type silicone rubber, silicone resin and modified materials. With the improvement of downstream high-end manufacturing requirements for material performance, the structural optimization and synthesis process upgrading of vinyl silicone oil have become the core driving force for the high-quality development of the industry.
The molecular structure is the core determining the performance of vinyl silicone oil, and its core feature is the synergistic effect between the polydimethylsiloxane main chain and the vinyl reactive groups. The polydimethylsiloxane main chain endows the product with excellent high and low temperature resistance, which can maintain stability in a wide temperature range of -50℃~200℃, and also has good hydrophobicity, electrical insulation and chemical inertness. As a reactive functional group, vinyl can undergo addition reaction with silanes containing Si-H bonds to achieve rapid crosslinking. The content and distribution of vinyl (terminal vinyl, side vinyl, terminal and side divinyl) can be flexibly adjusted, directly determining the crosslink density, hardness and mechanical properties of downstream products. Terminal vinyl silicone oil focuses on improving product toughness and ductility, side vinyl silicone oil focuses on improving crosslinking efficiency and hardness, and terminal and side divinyl silicone oil balances toughness and hardness, adapting to the needs of different scenarios.
At present, the mainstream synthesis process of vinyl silicone oil is mainly alkali-catalyzed equilibrium method. Using octamethylcyclotetrasiloxane (D4) and tetramethyldivinyldisiloxane (MMVi) as raw materials, under the action of alkali catalysts such as potassium hydroxide and tetramethylammonium hydroxide, the finished product is obtained through ring-opening polymerization, equilibrium reaction, neutralization, removal of low-boiling substances and other processes. This process has the advantages of simple operation, low cost and mature large-scale production, and is the main method of industrial production at present. However, the traditional process has shortcomings such as uneven vinyl distribution, large fluctuation of product molecular weight and high impurity content, which is difficult to meet the strict requirements of high-end addition-type silicone rubber.
Process upgrades focus on two major directions: precise control and purity improvement. By optimizing the raw material ratio and reaction parameters, new composite catalysts are used to achieve precise control of vinyl content and distribution, controlling the error of vinyl content within ±0.1%; the neutralization and low-boiling removal processes are improved, using vacuum distillation combined with membrane separation technology to completely remove catalyst residues and light component impurities, improving the product purity to more than 99.8% and reducing product volatile components. At the same time, a continuous production process is developed to replace the traditional batch production, improving production efficiency and product batch consistency, and promoting the upgrading of vinyl silicone oil from general-purpose to high-end customized type, meeting the demand for high-performance raw materials in semiconductor, aerospace and other fields.