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The raw rubbers of one-component and two-component condensation RTV silicone rubbers

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Two-component addition molding room temperature vulcanized silicone rubber is divided into elastic silicone gel and silicone rubber. The former has lower strength and the latter has higher strength. Their vulcanization mechanism is based on the addition reaction (hydrosilation reaction) between the vinyl groups (or propylene groups) on the end groups of the raw silicone rubber and the hydrosilyl groups on the cross-linking agent molecules. In this reaction, no by-products are emitted. Since low molecular substances are not released during the cross-linking process, the addition-molded room temperature vulcanized silicone rubber does not shrink during the vulcanization process. This type of vulcanizates are non-toxic, high in mechanical strength, excellent in hydrolytic stability (even under high pressure steam), good low compression set, low flammability, deep vulcanization, and vulcanization speed can be controlled by temperature, etc. Advantages, so it is a type of silicone rubber that is currently vigorously developed at home and abroad.


Two-component room temperature vulcanized silicone rubber can maintain long-term elasticity in the temperature range of 65~250℃, and has excellent electrical properties and chemical stability. It is resistant to water, ozone, and weathering. In addition, it is simple to use and has strong process applicability. Therefore, it is widely used as potting and molding materials. Various electronic and electrical components are coated and potted with room temperature vulcanized silicone rubber, which can protect against moisture (anti-corrosion, shock resistance, etc.). It can improve performance and stabilize parameters. Two-component room temperature vulcanized silicone rubber is particularly suitable for deep filling The sealing material also has a faster vulcanization time, which is superior to single-component room temperature vulcanized silicone rubber.


Two-component room temperature vulcanized silicone rubber has excellent anti-sticking performance after vulcanization, and the shrinkage rate is very small during vulcanization. Therefore, it is suitable for making soft molds for casting epoxy resin, polyester resin, polystyrene, Molds for polyurethane, vinyl, paraffin wax, low melting point alloys, etc. In addition, the high simulation performance of two-component room temperature vulcanized silicone rubber can replicate various exquisite patterns. For example, in the reproduction of cultural relics, it can be used to replicate ancient bronzes, and in the production of artificial leather, it can be used to replicate the skin patterns of snakes, pythons, crocodiles, pangolins and other animals.


   Two-component room temperature vulcanized silicone rubber should pay attention to several specific issues when using: first weigh the base material, crosslinking agent and catalyst separately, and then mix them in proportion. Usually the two components should be provided in different colors, so that the mixing of the two components can be observed intuitively, and the mixing process should be carefully operated to minimize the amount of entrapped gas. After the rubber material is uniformly mixed (uniform color), the bubbles can be removed by standing or decompression (vacuum 700 mmHg). After all the bubbles are discharged, put it at room temperature or at a specified temperature for a certain period of time to vulcanize into silicon Rubber.


In addition to methyl, the pendant groups on the siloxane main chain of the two-component room temperature vulcanized silicone rubber can be replaced with other groups such as phenyl, trifluoropropyl, cyanoethyl, etc., to improve its low temperature resistance and heat resistance , Radiation resistance or solvent resistance. At the same time, heat-resistant, flame-retardant, thermally conductive, and electrically conductive additives can be added as needed to prepare silicone rubber with ablation resistance, flame retardant, thermal conductivity and electrical conductivity.

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