Cause: Due to the large water permeability of silicone rubber, especially the mixing rubber made by precipitation silica, the moisture content of the mixing rubber increases linearly with the increase of the relative humidity in the air. When there is too much water, the silicone rubber changes from transparent to opaque. Especially in winter, due to the low ambient temperature, the water release time on the rubber surface is very slow or cannot be released at all, resulting in bubbles on the surface of the extruded product. Generally, the precipitation carbon dioxide is not suitable as a silicone rubber filler for extrusion molding due to its excessively high water content.

Solution: The surface of silica can be treated with alkoxysilane to make its hydrophilic surface into a hydrophobic surface, which reduces the water absorption of the rubber; it can also reduce the water absorption of the rubber through high temperature treatment to achieve Improve the bubble problem of extruded rubber.

At present, in the production of extruded rubber, in the existing formulation system, the 2 # structure control agent can be replaced with diethoxysilane to better handle the moisture on the surface of white carbon black. Of course, it is necessary in the production process. Pay attention to safety. The gas phase method can be used to mix the rubber in the first step. After the rubber is cold smelted, it is placed in a health room at 30 ~ 40 ℃ for 8 hours, and then the rubber is subjected to vacuum heat treatment. Strictly control the effective mixing time and temperature of the rubber, that is, the mixing time and temperature of the rubber in the high temperature section, thereby improving the bubble problem of the extruded rubber.