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Sulfur is difficult to dissolve in rubber, and its solubility decreases as the temperature rises. However, this brings another issue: when the temperature drops, the solubility of sulfur in the rubber compound also decreases, causing excess sulfur to precipitate on the surface, resulting in sulfur spraying. After sulfur spraying occurs in rubber, it not only affects the appearance of the product but also leads to a decrease in the adhesion of the rubber compound surface and a deterioration in the aging resistance of the product. So, in actual production, how can we operate to avoid sulfur spraying in rubber products and improve the performance of rubber products?

Sulfur is a traditional vulcanizing agent used in the vulcanization of rubber. The rubber compound vulcanized with sulfur exhibits high tensile strength, wear resistance, fatigue resistance, and excellent mechanical properties. Therefore, sulfur remains the mainstream vulcanizing agent in the production of modern rubber products.

When sulfur is added during mixing, if the mixing temperature is too high or the mixing is not uniform, it can lead to excessive dissolution of sulfur in the rubber compound or in certain parts of it. When the rubber compound is left to stand, if the amount of sulfur dissolved in the compound exceeds the saturation solubility limit or the supersaturation solubility limit at room temperature, sulfur will crystallize out of the compound, resulting in sulfur spraying. Excessive sulfur usage or severe sulfur deficiency during the production of rubber products are also causes of sulfur spraying issues.

Adjusting production formulas and processes: Generally, to prevent sulfur spraying on rubber products, rubber manufacturers will improve the rubber quality, mixing process, and vulcanization process. In rubber product formulas using sulfur as the vulcanizing agent, adding an appropriate amount of selenium can also reduce sulfur spraying. During the production process, sulfur should be mixed at the lowest possible temperature, and a small amount of softener should be added before adding sulfur.

Therefore, in rubber products, the main focus is generally on reducing the cost of rubber products, followed by appropriate improvements to the vulcanization process of rubber products; to fundamentally eliminate sulfur spraying, it is best to use insoluble sulfur.