Two-component condensation type room temperature vulcanized silicone rubber is the most common type of room temperature vulcanized silicone rubber. The raw rubber is usually a hydroxyl-terminated polysiloxane, which is then combined with other additives and catalysts to form a rubber compound. The viscosity can range from 100 centistokes to one million centistokes. The vulcanization reaction of two-component room temperature vulcanized silicone rubber is not initiated by water in the air, but initiated by a catalyst. Generally, the silicone rubber, filler, and cross-linking agent are packaged as one component, and the catalyst is packaged as another component alone or in other combinations, but the catalyst and the cross-linking agent must be packaged separately. Regardless of the packaging method, curing only begins when the two components are completely mixed together. A common cross-linking agent is ethyl orthosilicate, and the catalyst is dibutyltin dilaurate. Add appropriate fillers and additives according to the properties of the desired final product. In recent years, because dibutyltin dilaurate is a substance of medium toxicity, the addition of dibutyltin to food bags and plasma bags has been banned, and has basically been replaced by octyltin with low toxicity.

The curing time of two-component condensation type room temperature vulcanized silicone rubber mainly depends on the type, amount and temperature of the catalyst. The more catalyst used, the faster the sulfidation, and the shorter the standing time. At room temperature, the shelf time is generally a few hours. If you want to extend the shelf time of the rubber, you can use the cooling method. It takes about one day for the two-component condensation type room temperature vulcanized silicone rubber to achieve complete curing at room temperature, but it only takes one hour at 150 ° C. The synergistic effect by using the accelerator γ-aminopropyltriethoxysilane can significantly increase its curing speed. Two-component room temperature vulcanized silicone rubber can maintain elasticity for a long time in a temperature range of 65-250 ° C, 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 a potting and molding material. Various electronic and electrical components are coated with room temperature vulcanized silicone rubber, and can be protected against moisture (anti-corrosion, shock, etc.). It can improve performance and stability parameters. Two-component room temperature vulcanized silicone rubber is particularly suitable for deep-water irrigation. The sealing material has a faster curing time, which is superior to the one-component room temperature vulcanized silicone rubber.

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

When using two-component room temperature vulcanized silicone rubber, several specific problems should be paid attention to when using it: first weigh the base material, crosslinker and catalyst separately, and then mix them in proportion. Generally, the two components should be provided in different colors, so that the mixing of the two components can be visually observed, and the mixing process should be handled carefully to minimize the amount of entrained gas. After the rubber is mixed (uniform color), the air bubbles can be removed by standing or decompressing (700 mm Hg vacuum). After all the air bubbles have been discharged, they can be vulcanized into silicon at room temperature or at a specified temperature for a certain period of time. Rubber.

In addition to the methyl group, the side groups of the main component of the two-component room temperature vulcanized silicone rubber siloxane 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, heat-conducting, and conductive additives can be added as needed to produce a silicone rubber with ablation-resistant, flame-retardant, heat-conducting, and conductive properties.