Silicone rubber is gaining popularity in a wide array of industries. Its properties perform exceptionally well under many harsh and demanding conditions. Liquid silicone injection molding is the most efficient way to produce high quality custom silicone rubber keypads and components; with accurate, repeatable results.

Origin and Composition

Silicone rubber evolves from the inorganic origins of ordinary beach sand. The unique chemistry resulting from the silicon-oxygen (Si-O) polymer backbone is responsible for the rugged temperature stability of silicone rubber, as well as its extreme resistance to oxidation and ozone degradation. This silicon-oxygen linkage is the same as to the chemical bond found in highly stable materials such as sand and glass, and is responsible for its outstanding high temperature performance, as well as its general resistance to deterioration under high and low temperatures and harsh environments.

Many organic polymers contain unsaturated double bonds in their primary backbone, which are particularly susceptible to oxidation and ozone deterioration. The absence of any unsaturation in the silicone backbone makes it highly durable and perform exceptionally without fail for the life of the component.

Properties and Crosslinks
A number of curing agents can be added to the raw material to ensure proper curing. The most common agent for silicone rubber compounds are organic peroxides which, when heated, decompose to form free radicals that react with the pendant organic groups on the silicone polymer. The result is a crosslink between the polymer chains, the number and distribution of which influences the final physical property profile of the cured rubber.

Silicone rubber’s low relative viscosity and fast cure rate make it an excellent material for liquid silicone injection molding. Injection molding cure cycles are faster than other methods, tending to be between 0.5 and 3 minutes, depending on part size, and mold shrinkage tends to be lower than other molding methods due to high injection pressures. Balanced gates and venting are designed into the mold to avoid air entrapment and ensure complete fill in multi-cavity molds.

At SITECH, we use the highest quality silicone rubbers from GE and Dow, in combination with the latest injection molding technology and machinery, to produce the highest quality silicone rubber components available. We offer rapid prototyping, custom designs, color matching to existing products and custom decorating, or screening, to help your products stand out. For all your silicone rubber needs, trust SITECH’s experience and expertise to bring your designs to fruition.