Two component liquid silicone is a polymer material that solidifies through chemical cross-linking reactions, consisting of a mixture of components A and B. It is widely used in fields such as mold manufacturing, electronic packaging, and medical equipment. The diversity of its performance comes from the precise proportioning of raw materials and the fine control of reaction mechanisms.

Component A, as the main component of the base adhesive, mainly contains end vinyl polydimethylsiloxane. This linear polymer molecular chain has active vinyl groups at both ends, and its molecular weight directly determines the hardness and flexibility of silica gel. For example, low molecular weight polymers endow materials with lower viscosity and higher fluidity, making them suitable for making soft silicone gel; High molecular weight polymers provide higher mechanical strength and are suitable for hard or high elasticity demand scenarios. To enhance performance, gas-phase white carbon black is often added as a reinforcing filler in component A. Its nanoscale particles combine with siloxane chains, significantly improving tensile strength and tear strength. In addition, low viscosity silicone oil is introduced as a diluent to adjust the operation time after mixing to avoid premature gel.

The B component is responsible for crosslinking and catalytic functions, and the core raw material is hydrogen containing silicone oil. The densely distributed silicon hydrogen bonds (Si-H) on its molecular chain are the key to crosslinking reactions. Under the action of platinum catalyst, they undergo silicon hydrogen addition reaction with the vinyl group of component A, forming a three-dimensional network structure. The concentration and type of platinum catalyst directly affect the curing rate, for example, Karstedt catalyst is widely used due to its high efficiency and stability. To prevent immediate solidification after mixing, inhibitors such as ethynylcyclohexanol need to be added to component B to temporarily passivate the catalyst activity and extend the operating window period.

The mixing ratio of the two components and the selection of fillers are the core of performance customization. For example, increasing the amount of hydrogen containing silicone oil can improve the crosslinking density and increase the hardness of silicone from Shore A5 to 80, but excessive use may lead to increased brittleness. The composite filler system of gas-phase white carbon black and quartz powder can not only reduce costs, but also balance mechanical properties and flowability. In addition, for special needs such as conductive silicone, silver powder or nickel coated graphite will be added, while medical grade products require strict control over the use of biocompatible fillers.

The efficiency of the hydrosilylation reaction during the curing process is affected by temperature, humidity, and mixing uniformity. Under typical reaction conditions, when A/B components are mixed in a 1:1 volume ratio, the platinum catalyst activates the addition of Si-H and vinyl groups, generating stable Si-C bonds. This reaction can be carried out at room temperature, but heating can accelerate curing and shorten demolding time. The presence of inhibitors allows for adjustable operating times ranging from a few minutes to several hours, adapting to different process requirements.

Ultimately, the performance of two-component liquid silicone gel is a comprehensive result of the scientific proportioning of raw materials and process control. From basic polymers to functional fillers, the selection of each component needs to balance parameters such as fluidity, mechanical strength, and curing speed to meet diverse application scenarios from precision molds to high-temperature resistant electronic packaging.

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