1. component RTV silicone rubber

The vulcanization reaction of single component RTV silicone rubber is triggered by moisture in the air. The commonly used crosslinking agent is methyltriacethoxylsilane, whose Si-O-C bond is easily hydrolyzed. Acetoxyl is combined with hydrogen in water to form acetic acid, and the hydroxyl in water is moved to the original position of acetoxyl, becoming trihydroxymethylsilane. Trihydroxymethylsilane is extremely unstable and readily condenses with linear organosilicon with hydroxyl terminal group to form crosschain structure. At ordinary times, silicone rubber containing silicone alcohol end group and filler, catalyst, crosslinking agent and other coordination agents into a sealed hose, when used by the container extrusion, with the help of water in the air and vulcanized into elastomer, at the same time release of low molecular matter. Crosslinking agent in addition to methyl triacethoxy silane, can also be containing alkoxy, oxime, amine, amide, ketone group silane. When and alkoxy chain after release, known as alcohol type one-component room temperature vulcanized silicone rubber, when the cross-linking with oxime generated oxime, called oxime type room temperature vulcanized silicone rubber, therefore, as the cross-linking agent, one-component RTV silicone rubber for acid type, oxime type, type to take off the alcohol, amine, amide and take off the ketone etc as many varieties, But deacidification is the most widely used one.
The curing time of single component RTV silicone rubber depends on the curing system, temperature, humidity and the thickness of the silicone rubber layer. Improving the temperature and humidity of the environment can speed up the curing process. Under typical environmental conditions, the surface of silicone rubber can be non-viscous after 15 ~ 30 minutes, and the thickness of 0.3cm rubber layer can be cured in one day. The depth and strength of curing will gradually increase in about three weeks.

Single component RTV silicone rubber has excellent electrical properties and chemical inertia, as well as heat resistance, natural aging resistance, flame resistance, moisture resistance, air permeability and other properties. They remain elastic for a long time in the range of -60 ~ 200℃. It is not endothermic and exothermic when curing. After curing, the shrinkage rate is small and the adhesion of the material is good. For this reason, it is mainly used as a binder and sealant. Other applications include in-situ gaskets, protective coatings and caulking materials. Many single-component silicone rubber adhesives are formulations that exhibit self-adhesive properties for a wide variety of materials such as most metals, glass, ceramics and concretions, such as exposed aluminum with shear strength up to 200 lb · ft/" 2 and tear strength up to 20 lb · ft/" 2 (0.35 joule/cm 2). When bonding is difficult, the bonding strength can be improved by using a primer on the substrate, which can be a reactive silane monomer or resin. When they are cured on the substrate, a modified surface suitable for silicone bonding is generated.

Although the single-component RTV silicone rubber is convenient to use, because its vulcanization is based on the moisture in the atmosphere, the thickness of vulcanization is limited, and can only be used for occasions requiring the thickness of less than 6 mm.

The curing reaction of single component RTV silicone rubber is carried out gradually from the surface to the depth, the thicker the rubber layer, the slower the curing. When the deep also want to fast curing, can use layered watering gradually curing method, each time can add some glue, such as curing after adding, so that can reduce the total curing time. The addition of magnesium oxide can accelerate the vulcanization of the deep glue.