Silicone processing equipment and techniques

Silicone is a synthetic material composed of silicon, oxygen, carbon, and hydrogen. Being one of the main ingredients in silicone, the chemical element silicon is most commonly found in quartz, chemically known as silicon dioxide, from which it is reduced in a silicon furnace at temperatures as high as 1800°C. The leftovers of metallurgical-grade silicon are ground into fine powder. For silicone synthesis, it is crucial to add methanol to silicon to create chloromethane. Subsequently, a Müller-Rochow process starts by using a fluidized bed reactor heated at 300°C to trigger a reaction among particles forming a crude silane mixture.

The mixture is separated into various chlorosilane versions during a distillation process, and each version can further be processed depending on the desired end-product. Converted to polysiloxane chains via hydrolysis and polycondensation, difunctional chlorosilanes can be used as silicone fluids in cosmetics, textiles, and silicone rubber. As water-repellent yet breathable, trifunctional chlorosilanes are used in the construction industry. The three-dimensional silicone-resin networks are produced by undergoing hydrolysis and catalytic condensation. Finally, tertrafunctional chlorosilanes is used to manufacture pyrogenic silica, made by burning a crude silane mixture under a stream of hydrogen and air.

Silicone rubber production methods: extrusion

Silicone rubber is a highly versatile material that can be produced by a number of methods such as extrusion, injection molding, liquid injection molding, compression molding, calendering, and transfer molding.

Silicone rubber production methods: liquid injection molding

Liquid injection molding (LIM), also known as liquid silicone rubber (LSR), is used to produce high-volume durable parts and is suitable for creating complicated geometries.

Solid and liquid silicone rubbers

Silicone rubber can be classified based on its viscosity – the difference between solid and liquid silicone rubber. Long chains of polymers with a high molecular weight result in a high consistency rubber, which is solid. Solid silicone is used for a variety of daily and industrial products. On the contrary, silicone rubber has a liquid texture when it contains polymers of lower molecular weight and shorter chains.

Due to it being safe as there were no added chemicals such as vulcanizing agents during molding, this type of silicone is used in the production of baby products as well as kitchen and medical supplies. Concerning the difference in production liquid silicone is injected into the mold through a vulcanization screw at a mold temperature of 170-200°C. Solid silicone, however, is cut into suitable size pieces and compression-molded.