Insoluble sulfur is a polymer of sulfur that is insoluble in carbon disulfide and water. It has unstable properties and is easily converted into insoluble sulfur. As the temperature increases, the conversion rate accelerates. To prevent conversion, small amounts of chlorine, bromine, iodine, sulfur monochloride, and dienes can be added. take α- Sulfur is heated to a high temperature (near boiling point), and when it becomes a black brown viscous liquid, it quickly cools down to polymerize into insoluble sulfur. Overheated sulfur vapor can also be sprayed into cold water to quickly cool to below 90 degrees Celsius.
Insoluble sulfur is commonly used as a vulcanizing agent for special rubber products. Compared to ordinary sulfur, it has the following advantages:
1. Insoluble sulfur exists in a dispersed state in rubber, ensuring that the rubber material does not frost and has good viscosity, while also ensuring the appearance quality of light colored products.
2. Insoluble sulfur is uniformly dispersed in the rubber material, effectively resisting the aggregation of sulfur and reducing the tendency of burning during the storage process of the rubber material.
3. Insoluble sulfur ensures that the rubber material does not spray frost during storage, maintaining uniform performance of the rubber material components. Prevent contamination of products and molds, and remove the coating process added to overcome frost spraying, providing conditions for production linkage.
4. Insoluble sulfur prevents rubber from migrating between adjacent layers. Especially in the rubber materials of cisplatin and butadiene rubber, the migration rate of ordinary sulfur is very high, which can be avoided by adding insoluble sulfur.
5. It can maintain the adhesion between semi-finished components, which is beneficial for molding operations and ensures the uniformity of product vulcanization, ensuring product quality.
Insoluble sulfur can be used to manufacture tires, tapes, hoses, rubber shoes, industrial products, and latex products, and has been widely used in the bonding of rubber and steel wires. When used as a vulcanizing agent, insoluble sulfur can be directly added to the rubber material during mixing. Ordinary sulfur should be added on the cold roller of the open mill, and it is best to add it after other additives are added. Insoluble sulfur can be added to the internal mixer, but it should be added at a temperature below 90 degrees before discharging. When used for soft rubber, the general dosage is 0.2-5.0 parts by mass, and when used for hard rubber, the dosage can reach up to 25-40 parts by mass.