Overview of Room Temperature Vulcanized Silicone Rubber

Room temperature vulcanized silicone rubber (RTV for short) refers to a type of silicone rubber that can be vulcanized at room temperature without heating. Room temperature vulcanized silicone rubber is a silicone rubber with hydroxyl (or acetoxy) end groups, low molecular weight, and usually a viscous fluid. This type of rubber can be vulcanized at room temperature to form an elastomer after adding an appropriate amount of reinforcing filler, vulcanizer and catalyst (or under the action of moisture in the air). After complete vulcanization, it has good heat resistance, cold resistance, dielectric properties, etc., but its mechanical strength is relatively low, and it can be used for casting and coating rubber. Room temperature vulcanized silicone rubber can be divided into two types: one-component type and two-component type.

Room temperature vulcanized silicone rubber is all liquid. It can be divided into three types according to its composition, vulcanization mechanism and use process, namely one-component room temperature vulcanized silicone rubber, two-component condensation type room temperature vulcanized silicone rubber and two-component addition type room temperature vulcanized silicone rubber. These three series of room temperature vulcanized silicone rubber have their own characteristics: the advantage of single-component room temperature vulcanized silicone rubber is that it is easy to use, but the deep curing speed is difficult; the advantage of two-component room temperature vulcanized silicone rubber is that it does not release heat during curing, has a very small shrinkage rate, does not expand, has no internal stress, and can be cured both internally and on the surface at the same time, and can be deeply vulcanized; the vulcanization time of addition-type room temperature vulcanized silicone rubber is mainly determined by temperature.

Two-component room temperature vulcanized silicone rubber is made of silicone rubber containing terminal hydroxyl groups, reinforcing fillers, vulcanizing agents, etc., and catalysts are added when used. Medical | Education | Network Collection and Arrangement Commonly used vulcanizing agents are organic tin salts, such as dibutyltin dilaurate, and the dosage is generally 0.5 to 5 parts or stannous octoate, which has stronger catalytic ability than dibutyltin dilaurate. During vulcanization, under the action of the catalyst, the silicone rubber containing terminal hydroxyl groups and the vulcanizing agent undergo a dealcoholization condensation reaction to form a cross-linked structure. The vulcanization speed can be adjusted by changing the dosage of the vulcanizer and the catalyst. Generally, when the dosage is large, the vulcanization speed is fast, and vice versa. During the vulcanization process, the generated alcohol substances gradually diffuse and escape from the vulcanized rubber.

Single-component room temperature vulcanized silicone rubber is made of silicone rubber with acetoxy groups at the end groups, reinforcing fillers and other additives. No catalyst is required when using it. After taking it out of the sealed package, it can be vulcanized into an elastomer by reacting with moisture in the air. This type of silicone rubber has good adhesion to metals, glass and plastics. Its disadvantage is that acetic acid is generated during the vulcanization process. Although it can diffuse and escape from the vulcanized rubber, it has a corrosive effect on the contacting objects, especially metals. The single-component type is convenient to use and is particularly suitable for sealing, caulking and other purposes.

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