Processing Silicone Rubber - Wacker Chemie AG


Processing Silicone Rubber

  • Silicone Rubber (RTV-1/RTV-2); Silicone Gels
  • Liquid Silicone Rubber (LSR)
  • Solid Silicone Rubber (HTV)

Silicone Rubber (RTV-1/RTV-2); Silicone Gel

RTV silicones and gels are often applied by means of an automatic metering unit

One- and two-part RTV silicone rubbers resemble gels in that they are made up of low molecular-weight polymers. As a result, these silicone rubbers generally have good flow properties without external pressure. However, individual grades are modified for the particular application, for example as pastes and/or shear-thinning grades. Depending on the viscosity and the specific rheological properties, these materials are dispensed or sprayed via metering systems at low pressure. Manual processing is also possible.

Advantages:

  • The rheological properties can be varied within a wide range, from low viscosity to paste-like.
  • They are ideally suited for manual tests in the lab
  • economic production of large series

Procedure

  • Dispensing
  • Manual processing
  • Spraying
  • Dipping
  • Compression
  • Transfer Molding

Liquid Silicone Rubber (LSR)

Schematic view of the injection molding process

Liquid silicone rubbers are processed by injection molding. However, these materials only become really liquid under shear, at the high pressure during mold filling. When stationary, they are usually paste-like liquids with a consistency like honey. Liquid silicone rubber is always addition-curing (platinum-catalyzed).

Advantages:

  • Short cycle times (low viscosity, high curing speed)
  • Fully automated process
  • Molds with up to 256 cavities
  • Suitable for complex part geometries
  • 2K injection molding
  • No need for secondary finishing

Solid silicone rubber (HTV)

Extrusion of ELASTOSIL® solid silicone rubber into tubes

Solid silicone rubber contains polymers with a high molecular weight and relatively long polymer chains. It is referred to as HTV (= high-temperature-vulcanizing). We offer you solid silicone rubber in two product lines: peroxide-curing grades and addition-curing (platinum-catalyzed) grades. The standard form of supply of solid silicone rubber is in block form. In the ready-to-use compounds, the material is also supplied in the form of strips, cord, pellets and profile strips.

Advantages:

  • Very variable processing permits various parts to be realized with just a few basic grades.
  • High flexibility for short-to-medium series

Processes:

  • Press vulcanization, injection molding
  • Extrusion (particularly economical)