Chemical process analysis of RTV SILICONE SEALANT ADHESIVE (ACID)
RTV SILICONE SEALANT ADHESIVE (ACID) one-component and two-component condensation type RTV silicone rubber raw rubber is α, ω-dihydroxy polysiloxane; addition type RTV silicone rubber contains alkenyl and hydrogen Polysiloxane with side group (or end group) can achieve good curing effect when it is cured at a temperature slightly higher than room temperature (50-150°C), so it is also called low-temperature vulcanized silicone rubber (LTV) ). These three series of room temperature vulcanized silicone rubber have their own advantages and disadvantages: the advantage of one-component room temperature vulcanized silicone rubber is that it is convenient to use, but the deep curing speed is difficult; the advantage of two-component room temperature vulcanized silicone rubber is that it does not exotherm during curing , the shrinkage rate is very small, no expansion, no internal stress, curing can be carried out on the inside and 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, so the vulcanization can be controlled by adjusting the temperature speed.
The vulcanization reaction of one-component RTV silicone rubber is initiated by moisture in the air. The commonly used cross-linking agent is methyltriacetoxysilane. Its Si-O-C bond is easily hydrolyzed. The acetoxy group combines with the hydrogen group in water to form acetic acid, and moves the hydroxyl group in the water to the original acetoxy group. In position, it becomes trihydroxymethylsilane. Trihydroxymethylsilane is extremely unstable, and it is easy to condense with linear silicone whose terminal group is a hydroxyl group to form a cross-linked structure.
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MODIFIED ACRYLIC AB ADHESIVE (BOXES) uses methyl methacrylate as the main raw material, with tougheners, reinforcing agents, stabilizers, initiators, polymerization inhibitors, etc., two components synthesized through advanced technology (A, B) Reactive structural adhesive.