Solid Silicone Rubber (HTV)
WACKER offers two types of solid silicone rubber: ELASTOSIL® R (peroxide-curing grades) and ELASTOSIL® R plus (platinum-catalyzed, addition-curing grades). You may choose between base stock and ready-to-use mixtures. Crosslinkers, stabilizers, pigments and other additives round out our product offering.
ELASTOSIL® R solid silicone rubber grades are peroxide-curing. They can be processed by conventional methods, such as extrusion, calendering, compression and transfer molding, or injection molding. They cure in heat and are ideal for manufacturing a variety of silicone rubber articles.
The products in the ELASTOSIL® R plus series combine the advantages of solid silicone rubber with those of addition-curing liquid silicone rubber, namely outstanding mechanical properties combined with high productivity. ELASTOSIL® R plus grades are available as 1-part and 2-part systems.
Applications
Heat-curing silicone rubber is used in a diverse range of applications across all kinds of industries:
- Automotive and aerospace
- Electrical engineering
- Transmission and distribution cables (T&D)
- Construction
- Mechanical and plant engineering
- Consumer goods and the food industry
- Health care and medical technology
Under the SILMIX® brand, we also develop, compound and produce customized, ready-to-use silicone rubber compounds for you – at various locations around the world, and to the same high WACKER quality standard.
Processing Forms
ELASTOSIL® solid silicone rubber grades are processed by conventional methods, such as extrusion, injection, transfer and compression molding, and by calendering.
Type of rubber to use
| Process | Solid Silicone Rubber | Liquid Silicone Rubber |
|---|---|---|
| Extrusion | x | |
| Coextrusion | x | |
| Compression molding | x | |
| Transfer molding | x | |
| Injection molding | x | x |
| Calendering | x | |
| Low-pressure filling | x (low-viscosity grades) |
Schematic diagram of an extruder fitted with a crosshead die
Extrusion is a continuous manufacturing process in which silicone rubber is forced through a die and then vulcanized. The die gives the extrudate its shape. The necessary pressure is produced via a conveying screw, in which the material is homogenized, compressed and vented.
Extruded products include:
- Tubing
- Profiles
- Cables
- Flat tapes
- Round cords
Schematic diagram of compression molding
Compression molding processes are used for a wide range of applications. ELASTOSIL® solid silicone rubber is cured in molds by heat and pressure. Compression and transfer molding are the preferred methods for solid silicone rubber.
Injection molding is the most popular and efficient process for mass-producing products that must meet strict demands for consistently high quality. It is characterized by high dimensional accuracy, produces high-quality parts without the need for secondary finishing, and allows much shorter production cycles than other processes. The disadvantages are higher mold and machine costs, though these are offset by the high productivity.
Injection molding is ideal for small to medium-sized parts and large production runs, such as
- Nipples for baby bottles
- Gasket rings
Schematic diagram of calendering
Silicones can be used for coating nearly any type of fabric. The art of formulation requires a great deal of experience and creativity, and a wealth of knowledge about relevant chemical and processing relationships. WACKER SILICONES’ technical service specializes in precisely that: we will advise you on formulations and will conduct application-related testing for you. We will gladly show you how innovative coating technologies can provide opportunities that will prove advantageous to your specific needs. Upon request, we can also carry out pilot runs for you (product width up to 90 cm).
Silicones can be applied by all the usual textile coating methods. The most common is calendering of solid silicones. After careful cleaning, coating equipment used for silicones can even serve for processing other coating compounds, such as PVC, PUR and acrylates. We recommend aliphatic solvents such as white spirit or isoparaffins as cleaning agents. After cleaning, the heating tunnel should be held at a temperature of at least 150 °C for about an hour before switching over to other materials.
Delivery Forms
ELASTOSIL® solid rubber is supplied as standard in slabs measuring 90x100 mm (cross-section) wrapped in PE film inside cardboard boxes. For special requirements, we also offer our ready-to-use mixtures in the form of strips, round cord, pellets and profile strips.