Silane polyurethane hybrids

Silane polyurethane hybrids are urethane-based polymers which have been end-capped with reactive silane groups. Urethane-based and silicone-based sealants are two major, single component sealant technologies useful in many applications. For instance, they are used for sealing and bonding cement-containing compounds, metals, plastics, and glass. 

Urethane-based sealants improve rheological and mechanical properties, and adhere well to a variety of substrates as do silicone-based sealants. However, urethane-based sealants tend not to accumulate dirt and dust and are easier to compound than silicone-based sealants. For this reason, hybrid sealants based on moisture-curable hydrolysable urethane prepolymers have been proposed [43]. Silane polyurethane hybrid sealants are systems that maximise the beneficial features of each of the urethane-based and silicone-based technologies, whilst minimising the undesirable characteristics. 

Figure 7.6 Schematic representation of hard clusters in (a) a polyurethane network composed of a long diol, a triol, and a diisocyanate (polyaddition reactions, Chapter 2). (b) a hybrid inorganic-organic network composed of a silane end-capped long diol (polycondensation reactions, Chapter 2).

Reactive adhesives for elastic bonding are available as one-part and two-part systems, based on polyurethane (PUR), polysulphide, silicone or silane-terminated polymers, such as PUR-Hybrids and Modified Silicones (MS). These adhesive systems can he applied cold or warm or mixed with a water-based Booster component. 

Apart from the development of polyurethane adhesives and sealants with isocyanate reactive groups, a new type of silane-terminated polymer adhesive has been developed called Polyurethane (PUR)-Hybrids. They and modified silicones (MS) and provide the benefits of ... 

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