WACKER produces and markets silicone resins under the brand name SILRES®. Silicone resins are classified as organopolysiloxanes and consist of an irregular three-dimensional network composed of mainly tri- or tetra-functional units.
These organopolysiloxanes are very stable due to the strength of the Si-O bond. Silicone resins can be combined with many organic polymers, and this makes it possible to tailor a large number of properties to the intended application, e.g. curing behavior, flexibility, adhesion, and resistance to weathering.
SILRES® silicone resins are available in different product forms:
- Silicone resin emulsions
- Silicone resin solutions
- Silicone resin copolymers
The organic substituents bonded to the silicon atom can be varied to provide important macroscopic properties.
- Heat resistance
- Outstanding oxidation resistance
- Water-repellency with simultaneous vapor permeability
- Outstanding mechanical properties
- Ideal dielectric behavior
- Permanent resistance to weathering and UV radiation
- Very low VOC content (volatile organic compounds)
SILRES® silicone resins serve in a variety of applications, such as:
- Binders for silicone resin emulsion paints and plasters
- Binders for industrial coatings
- Binders for organic fillers, e.g. pre-ceramics
- Binders for fabrics or textile webs in the composites industry
- Impregnating agents for electrical windings
- Hydrophobic agents for masonry protection
- Modifiers for alkyd, epoxy, polyester and acrylic paints.
- Release agents for the plastics industry
Silicone Resin Emulsions
On mineral building substrates and coatings, silicone resin emulsions form a stable three-dimensional network that is weatherable and water-repellent and is firmly held to the mineral substrate by strong chemical bonds. This silicone resin network is key to their versatility as binders for masonry protection applications. Now that products are increasingly required to be environmentally and user-friendly – which essentially means they must have a low VOC content (volatile organic compounds) – water-based heat-resistant coatings are growing in importance. Coatings formulated with silicone resin emulsions have a much-reduced volatiles content compared with those made with traditional solvent-based resins.
Silicone Resin Solutions
Traditional silicone resin solutions are very easy to use, because they dry very rapidly in air and offer good adhesion and initial hardness. Low-solvent silicone resin products are available, though, for formulating high-solids coatings. Silicone resin solutions are chiefly used for heat-resistant coatings and weatherable topcoats.
Silicone Resin Copolymers
The properties of organic resins, especially alkyd, polyester, epoxy and acrylic-based types, can be greatly enhanced by modification with silicone resins. Thus, depending on the type of organic resin, the coatings produced with silicone resin copolymers are more resistant to heat, weathering and UV radiation. In addition, these coatings are often more economical for end customers due to their longer lifetime.