At a Glance
Silicone resins are classified as organopolysiloxanes and are an irregular three-dimensional network or principally tri or tetrafunctional units. Thanks to the high Si-O bond energy, the various organopolysiloxanes are very stable. The organic substituents bonded to the silicon atom additionally determine important macroscopic properties. Silicone resins are therefore permanently resistant to temperature, effects of weathering and UV radiation.
Moreover, silicone resins can be combined with organic polymers. This allows the properties of the organic polymers to be optimized, for example towards higher thermal stability and increased weathering resistance.
Silicone resins resist temperatures up to +350 °C, and in formulations with suitable fillers and pigments, even up to +650 °C. Silicone resins are also impressive for their outstanding oxidation resistance, their water-repellency with simultaneous vapor permeability, as well as their outstanding mechanical properties, thus ensuring that the end product is durable, sustainable and economic. Not least, they have an ideal dielectric behavior.
Silicone resins are primarily used as hydrophobic agents for building protection, as binders for silicone resin emulsion paints and plasters for building facades, and in industrial coatings, and in these applications are marketed by WACKER under the trade name SILRES®. In industrial coatings, silicone resins act both as binders for highly heat resistant coatings and modifiers of alkyd, epoxy, polyester and acrylic paints.
Silicone resins are also used in a number of other industries, for example as release agents in the plastics industry, as binders for organic fillers, for example for preceramics, in socket cements of lamps or in coatings of resistors and capacitors. In the production of composite materials, they serve as binders for fabrics or textile webs. Silicone resins are also used for impregnating the windings of electrical machinery.
Silicone resin emulsions
On mineral construction material surfaces and coatings, silicone resin emulsions form a stable three-dimensional, weathering-resistant and water-repellent silicone resin network that is strongly chemically bound to the mineral substrate. This network is the basis of their versatility as binders for building protection applications. In view of the stricter requirements for environmentally and user friendly products – specifically that means low VOC (volatile organic compounds) and non HAPS (hazardous air pollutants) – water-based high-temperature coatings are increasing in importance. Compared with traditional solvent-based resins, silicone resin emulsions reduce the volatile components of high-temperature coatings considerably.
Silicone resin solutions
Traditional silicone resin solutions are very easy to use, since they dry very rapidly in air and offer good adhesion and initial hardness. Moreover, there are silicone resin products with low solvent content for formulating "high-solids" coatings. Silicone resin solutions are used, in particular, for high-temperature coatings and weathering-resistant top coats.
Silicone Resin Copolymers
Organic resins, in particular alkyd, polyester, epoxy and acrylic-based resins, can be modified with silicone resins to give them significantly improved properties. Thus, depending on the type of organic resin, the coatings produced with silicone resin copolymers are more heat, weathering and UV resistant. In addition, these coatings are also often more economical for end customers due to their longer lifetime.