For years, many silicone rubber manufacturers have focused primarily on marketing their products, without providing a clear understanding of how silicone rubber is made and what its components are. However, it’s essential for clients to know the general processes and raw materials involved in silicone rubber production.
Let’s begin with Vinyl Silicone Fluid, a type of polysiloxane that contains two or more -Si-CH=CH2 groups. It is a key ingredient in silicone rubber. By adding Vinyl Silicone Fluid, the rubber’s crosslink density is altered, enhancing its tear strength, tensile strength, and hardness.
Key Components of Platinum Cure Silicone Rubber:
- Silicone Base
The primary component of platinum silicone is often Polydimethylsiloxane, which contains two or more -Si-CH=CH2 groups. Typically, it is a type of linear polysiloxane, where vinyl groups are attached at both ends. (If only one vinyl group is present at one end, it is referred to as Vinyl Silicone Oil.) - Crosslinker
The Crosslinker is an organic silicon oligomer containing three or more -Si-H groups, commonly called methyl hydrogen silicone oil. It is one of the fundamental ingredients in platinum cure silicone rubber. - Platinum Catalyst
Several catalysts can initiate the Si-H reaction in addition-cure silicone rubber, but platinum is the most efficient. Using a platinum catalyst allows the silicone rubber to vulcanize at room temperature. By adding an inhibitor in the right proportion, the reaction speed and vulcanization process can be controlled. - Reinforcement Fillers
Silicone rubber made from Vinyl Silicone Fluid and Hydrosilicone Fluid alone does not exhibit strong mechanical properties, such as tear strength, tensile strength, or elongation. To improve these characteristics, reinforcement fillers like fumed silica, precipitation silica, or silicon powder are added. For clear silicone rubber, Methyl Vinyl MQ Silicone Resin is used to enhance its mechanical properties. - Other Additives
Various additives are included to achieve specific properties like different colors, improved thermal conductivity, flame resistance, electrical conductivity, thermostability, transparency, and more.