The mixing of silicone rubber can be carried out by using a two-roll open mill or a vacuum lifting machine. When using an open mill, the materials are weighed according to the formula. First, the raw rubber is wrapped around the rollers, and then the white and black parts and auxiliary materials are gradually added. The rollers are briefly maintained at a certain temperature to increase the "powder consumption" speed. The materials are mixed in a "truckload by truckload" manner, left for 24 hours, and then re-mixed. Finally, they become silicon compound rubber that can be processed into products. The open refining process is adopted, which involves low labor intensity, low production efficiency and relatively serious environmental pollution.
When manufacturing mixed rubber by the internal mixing process, first weigh each component material according to the formula list, and then carry out the batching operation in a common kneader. The raw rubber is added at one time, and the fillers and auxiliary materials are added in multiple times as required by the process formula. Then, start the machine for kneading to achieve the initial mixing purpose. After the material forms wettable lumps, it can be discharged. Then, a vacuum kneader is used for internal mixing. The two Z-shaped stirring blades of the kneader rotate in opposite directions to shear the rubber compound, gradually mixing it evenly. During vacuum kneading, the material is gradually heated to 170 to 180℃, and the vacuum degree within the system can be controlled within the range of -0.05 to -0.08MPa. The purpose of vacuuming is to extract moisture and low-molecular compounds from the material, thereby enhancing and stabilizing the performance of the rubber compound. The heating rate, vacuum degree, kneading time and discharge temperature during vacuum kneading are all important process parameters. They should be strictly controlled and reasonably adjusted to ensure the high quality of the compound rubber products. Vacuum internal mixing is used to manufacture compound rubber, which has high production efficiency, less dust flying and stable product quality. It is currently the main method for producing compound rubber.
The silicone rubber compound that has undergone vacuum kneading needs to be cooled and left to stand again. Then, it is re-mixed and thinned on an open mill to make the rubber compound more uniform and consistent, free of bubbles and burrs. After being filtered through a rubber filter using a 200-300 mesh stainless steel screen to remove various impurities, it can become the finished mixed rubber product and be packaged and stored in the warehouse.