Room temperature vulcanized silicone rubber (RTV) is a new type of silicone elastomer that was introduced in the 1960s. The most remarkable feature of this rubber is that it can be cured in situ without heating or pressing at room temperature, and it is extremely convenient to use. Therefore, it has become an important part of the entire silicone product. At room temperature, vulcanized silicone rubber has been widely used as an adhesive, sealant, protective coating, potting and molding material, and has its use in various industries. Room temperature vulcanized silicone rubber is known as liquid silicone rubber because of its low molecular weight. Its physical form is usually a flowable fluid or a viscous paste with a viscosity of between 100 and 1,000,000 centistokes. Depending on the requirements of use, the pre-vulcanized compound can be formulated as an automatic leveling infusion or a non-rogue but scratchable putty. The filler used in the room temperature vulcanized silicone rubber is similar to the high temperature vulcanized silicone rubber, and is reinforced with white carbon black to give the vulcanized rubber a tear strength of 10 to 60 kg/cm 2 . Adding different additives can make the rubber compound have different specific gravity, hardness, strength, fluidity and thixotropic properties, and make the vulcanized rubber have various special properties such as flame retardant, conductive, heat conduction and ablation resistance.




Room temperature vulcanized silicone rubber can be divided into one-component and two-component room temperature vulcanized silicone rubber according to its packaging method. According to the vulcanization mechanism, it can be divided into condensation type and addition molding. Therefore, room temperature vulcanized silicone rubber can be divided into three types according to 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. .




The raw rubber of the one-component and two-component condensation type room temperature vulcanized silicone rubbers are all α,ω-dihydroxypolysiloxane; the addition of room temperature vulcanized silicone rubber is an alkenyl group and a hydrogen containing side group (or terminal group). Polysiloxane is also known as low-temperature vulcanized silicone rubber (LTV) because it can obtain a good ripening effect at a temperature slightly higher than room temperature (50 to 150 ° C) during aging.




These three series of room temperature vulcanized silicone rubbers have their own advantages and disadvantages: single-component room temperature vulcanized silicone rubber has the advantages of convenient use, but deep curing speed is difficult; the advantage of two-component room temperature vulcanized silicone rubber is that it does not exotherm during curing. , shrinkage rate is small, no expansion, no internal stress, curing can be carried out at the same time inside and on the surface, can be deep vulcanized; the vulcanization time of the addition room temperature vulcanized silicone rubber is mainly determined by the temperature, therefore, the temperature can be controlled to control its vulcanization. speed.
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