Liquid silicone rubber is a type of organic silicon polymer material with unique semi fluid dynamic processing characteristics. Since its industrial application in the mid to late last century, it has gradually penetrated from the initial aerospace special field to almost all high-end manufacturing scenarios such as medical and health, electronic and electrical, daily consumption, and new energy, relying on its excellent high and low temperature resistance, physiological inertness, and molding adaptability.

It has become an irreplaceable type of elastic material in the modern industrial system. Unlike traditional solid silicone rubber, liquid silicone rubber presents a uniform liquid state before vulcanization, with viscosity covering a wide range from low fluidity thin paste to slowly flowing viscous state. It can be formed through automated methods such as injection molding without complex mixing and molding processes. The entire processing process has lower energy consumption and higher production efficiency, and the dimensional accuracy and appearance consistency of the product can also be better guaranteed.

From the perspective of the core vulcanization reaction mechanism, the two most mainstream categories of liquid silicone rubber are condensation vulcanization and addition vulcanization. The molecular structure design and crosslinking reaction pathway of the two are completely different, and they are also suitable for completely different application scenarios. Condensed sulfurized liquid silicone rubber is one of the earliest categories to achieve commercial application. Its crosslinking reaction relies on the condensation reaction of silicon hydroxyl groups and active groups under the action of catalysts, and a small amount of low molecular weight by-products are released during the reaction process.

Most of these materials are two-component systems, and after mixing the two components in proportion, they can be gradually vulcanized at room temperature without the need for additional heating equipment. The threshold for construction and use is extremely low, and they were widely used in low precision scenarios such as building sealing, ordinary potting, and handicraft replication in the early days. However, due to the limitations of the reaction mechanism, the vulcanization rate of such materials is slow, and the interior of thick walled products is prone to incomplete curing.

The slow release of by-products may also cause slight volume shrinkage during long-term use of the products, making it difficult to meet the requirements of mass production of high-precision industrial products. Currently, it is more concentrated in low value-added universal sealing and filling scenarios.

Addition vulcanization liquid silicone rubber is currently the most widely used category in high-end industrial fields. It relies on the addition reaction of vinyl siloxane and hydrogen containing siloxane catalyzed by platinum based catalysts to complete crosslinking. The entire reaction process does not generate any low molecular weight by-products. The vulcanized product has a dense structure, extremely low linear shrinkage rate, and much better dimensional stability than condensation vulcanization products.

Most of these materials are designed as a two-component proportional mixture system, and the viscosity before vulcanization can be flexibly adjusted according to processing requirements. They can be formulated into low viscosity grades with excellent fluidity, suitable for high-speed mold filling of precision small parts, or adjusted into paste grades with strong thixotropy, suitable for special processes such as dispensing and coating.

The vulcanization speed of addition vulcanization liquid silicone rubber is very sensitive to temperature, and can maintain a suitable period of several hours or even tens of hours at room temperature. Heating to the range of 100 ℃ to 200 ℃ can quickly complete vulcanization in seconds to minutes, perfectly adapting to the production rhythm of automated injection molding. It is the absolute mainstream material for current medical products, electronic accessories, high-end maternal and child products and other scenarios.