Injection molding silicone rubber foaming is a process that combines liquid silicone rubber (LSR) with a foaming agent and, after heating and pressurizing, forms a porous expanded product in a mold at one time.The main process is as follows:
Raw material preparation and mixing:
Liquid silicone rubber (LSR) is used as the base rubber, which is usually two-component (A/B component). Precisely mix liquid silicone gel with chemical foaming agents (compounds that usually decompose to produce gas at specific temperatures) and necessary color pastes and other additives. The mixing process must be uniform and avoid introducing gas in advance.
Injection molding:
The well-mixed liquid material is sent into the barrel of the injection molding machine through a metering pump. The machine injects a certain amount of liquid material into the pre-heated mold cavity. At this time, the mold temperature is usually controlled below the decomposition temperature of the foaming agent to prevent premature foaming during the mold filling process.
Foaming and vulcanization：
When the mold cavity is filled, the mold temperature rapidly rises above the decomposition temperature of the foaming agent (usually between 130°C and 180°C),The foaming agent begins to decompose upon heating, generating gases (such as nitrogen), which form a large number of tiny closed cells within the silica gel matrix.
Cooling and demolding：
After vulcanization is completed, wait for the mold to cool down, and then open the mold to take out the product.