In the formulation design of high-temperature vulcanized silicone rubber (HTV) and liquid silicone rubber (LSR), the "structured" phenomenon brought by the silica reinforcement system and the improvement of crosslinking efficiency are often difficult to balance - traditional hydroxyl silicone oil can effectively inhibit the structuring but cannot participate in crosslinking; while simply adding vinyl silicone oil can enhance crosslinking but has limited help for processing fluidity. The product we have launched, hydroxyl-terminated methyl vinyl silicone oil 1203V, introduces vinyl chain segments into the side chains of hydroxyl silicone oil molecules, enabling a single molecule to simultaneously possess the structural control function of hydroxyl and the crosslinking enhancement activity of vinyl. In silicone rubber processing, it shows better comprehensive effects than traditional solutions, providing an "efficient dual-effect" choice for silicone rubber formulation design.


I. Core Structural Characteristics and Physical Properties of the Product


Product hydroxyl-terminated methyl vinyl silicone oil 1203V is a colorless transparent liquid with a viscosity not exceeding 35 square millimeters per second at 25 degrees Celsius. The vinyl content is 6.5 to 7.5 moles per cent, moisture is no more than 0.35%, and hydroxyl content is not less than 6.0%. The flash point is not less than 60 degrees Celsius. The product's molecular ends are active hydroxyl groups, and the side chains contain vinyl groups. It is a modified poly siloxane with both hydroxyl reactivity and vinyl crosslinking activity. Its low viscosity makes it easy to disperse during mixing, allowing it to quickly come into contact with fillers such as silica black, ensuring the timely exertion of the structural control effect. The vinyl content can be customized according to customer requirements, providing flexible selection space for different crosslinking density requirements in formulations.


II. Dual Mechanism: Structural Control and Crosslinking Enhancement


The core application value of product hydroxyl-terminated methyl vinyl silicone oil 1203V lies in its unique bifunctional molecule design.


Firstly, the terminal hydroxyl groups play the role of structural control agents. During the mixing and vulcanization of silicone rubber processing, the active silicon hydroxyl groups on the surface of air-cast silica black easily react with the silicone rubber molecule chains, causing the rubber to gradually harden and lose plasticity, i.e., the "structuring" phenomenon. The hydroxyl groups at both ends of the product's molecule can form hydrogen bonds or undergo condensation reactions with the hydroxyl groups on the surface of silica black, effectively钝化 the active sites on the filler surface， thereby significantly inhibiting the structuring process and reducing the Marni viscosity of the mixed rubber， prolonging the safe storage time of the rubber. Studies have shown that hydroxyl silicone oil structural control agents have a better inhibitory effect on silicone rubber structuring than methoxy silicone oil and dimethyl diethoxy silicone oil.


Secondly， the side-chain vinyl groups participate in crosslinking reactions. Unlike ordinary hydroxyl silicone oil， the vinyl groups in the side chains of this product can undergo co-crosslinking reactions with the vinyl groups in the rubber molecule chains in the peroxide vulcanization system， chemically bonding the silicone oil chain segments to the crosslinking network. This design enables it to exert the structural control effect while also participating in the vulcanization reaction as a crosslinking enhancement component， achieving a better effect than simply adding vinyl silicone oil. The distribution of side-chain vinyl groups enables a more uniform suspended chain structure in the crosslinking network， helping to optimize the mechanical property distribution of the vulcanized rubber.


III. Main Application Areas


Product hydroxyl-terminated methyl vinyl silicone oil 1203V， with its dual functional characteristics， can play an important role in the following silicone rubber processing and application areas， including：


1. Structural control and performance optimization of high-temperature vulcanized silicone rubber (HTV). In the mixing and processing of HTV products such as molded parts， extrusion products， and cable insulation layers， this product can effectively inhibit the structuring of silica black， reduce the viscosity of the rubber， and improve processing fluidity； during the vulcanization stage， the side-chain vinyl groups participate in crosslinking， improving the tear strength and resilience of the vulcanized rubber. Patent technology indicates that in the base gel formulation, this product, together with end-alkylated silicone oil, silica, hexamethyldisilazane, etc., can be used in synergy to obtain a liquid silicone rubber composition with low compression deformation.


II. Formula Control of Liquid Silicone Rubber (LSR). In the injection molding LSR system, the low viscosity characteristic of this product is conducive to rapid mold filling, the hydroxyl group can improve the compatibility with fillers, and the vinyl group ensures the uniformity of deep curing. Its dual action mechanism helps LSR products achieve a balance between processing performance and mechanical properties.


III. Electrical Encapsulation Adhesives and Sealing Materials. As a functional additive, this product is added to electrical encapsulation adhesives, which can significantly improve the bonding performance and mechanical strength of the encapsulation adhesives. Its dual action helps enhance the reliability of the encapsulation materials in a humid and hot aging environment.


IV. Usage Suggestions and Process References


It is recommended to add this product during the freezing and grinding stage of the mixing process. At this stage, the contact with silica is the most thorough, and the structural control effect is the best. The dosage should be determined through experiments based on the type of silica and the rubber base formula. This product can be used alone or in combination with hydroxyl silicone oil. During storage and transportation, it should be avoided from direct sunlight and high temperatures. It must not be mixed with acids, alkalis, etc. The shelf life is 6 months under storage conditions and unopened. The product is available in two packaging specifications: 25 kilograms of plastic drums or 200 kilograms of iron drums. It is transported as a non-hazardous product.


V. Quality Assurance and Market Value


Product 1203V of hydroxyl-terminated methyl vinyl silicone oil has established a strict quality control system during the production process. Key indicators such as product appearance, viscosity, vinyl content, moisture, hydroxyl content, and flash point are tested throughout the process to ensure consistency and reliability between batches. As silicone rubber products continue to develop towards higher value and precision, the demand for special additives with dual roles as processing aids and functional fillers is steadily increasing. This product, with the collaborative design of hydroxyl and vinyl double functional groups, provides a "one-shot dual-effect" efficient solution for the silicone rubber processing industry. It shows good application prospects in HTV, LSR, RTV, and silica filler reinforcement systems, providing strong raw material support for the dual improvement of processing efficiency and performance quality of silicone rubber products.