Vulcanization Method, Time and Application of Two-component Room Temperature Vulcanized Silicone Rubber

Silicone rubber is a linear high molecular weight polysiloxane with a molecular weight generally above 150,000, and its structure is similar to that of silicone oil. According to the different organic groups linked to the silicon atom, silicone rubber has many varieties such as dimethyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl silicone rubber, fluorosilicone rubber, nitrile silicone rubber, ethyl silicone rubber, etc.

1. Vulcanization method of two-component room temperature vulcanized silicone rubber

The vulcanization reaction of condensed one-component room temperature vulcanized silicone rubber is initiated by moisture in the air. The vulcanization reaction of condensed two-component room temperature vulcanized silicone rubber is not initiated by moisture in the air, but by a catalyst. Usually, the raw silica gel, filler, and cross-linking agent are packaged as one component, and the catalyst is packaged separately as another component, or other combinations are used, but the catalyst and the cross-linking agent must be packaged separately. Regardless of the packaging method, curing begins only when the two components are thoroughly mixed together. The vulcanization reaction of the addition type two-component room temperature vulcanized silicone rubber is accomplished through the addition reaction of silicon hydrogen bonds and silicon vinyl groups in the presence of platinum metal catalysts.

2. Vulcanization time of two-component room temperature vulcanized silicone rubber

The vulcanization time of the two-component condensation type room temperature vulcanized silicone rubber mainly depends on the type, amount and temperature of the catalyst. The higher the amount of catalyst, the faster the vulcanization, and the shorter the rest time. At room temperature, the shelf time is generally a few hours. To prolong the shelf time of the rubber compound, the method of cooling can be used. Two-component condensation-type room temperature vulcanized silicone rubber takes about a day to fully cure at room temperature, but only 1 hour at 150°C. The curing speed can be significantly increased by the synergistic effect of using the accelerator γ-aminopropyltriethoxysilane.

3. Application of two-component room temperature vulcanized silicone rubber

Two-component room temperature vulcanized silicone rubber has excellent anti-sticking properties after vulcanization, and the shrinkage rate during vulcanization is extremely small. Therefore, it is suitable for making soft molds. In addition, the high simulation performance of two-component room temperature vulcanized silicone rubber can be used. Copy all kinds of 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 animals such as snakes, pythons, crocodiles, and pangolins, which has the effect of mixing the fake with the real.

Usually 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 performed carefully to minimize the amount of entrained gas. After the rubber compound is mixed evenly (the color is uniform), the bubbles can be removed by standing or decompression (vacuum degree of 700 mm Hg).