Oil filled sulfur powder is a powder with a particle size of about 150m, which is easy to fly and inconvenient to transport. At the same time, it is not easy to evenly disperse in the rubber during use, which is not in line with our original intention of using this vulcanizing agent and will also have a certain impact on the production environment. Therefore, oil can be filled in the powder to prevent the formation of dust, and vulcanizing agents can be better dispersed in the rubber, thereby avoiding frost and combustion of the rubber. Oil filled sulfur powder, the types of oil are generally aromatic oil and cycloalkane oil obtained from petroleum refining, and the oil content is generally 10% to 34%. Refined aromatic oil and cycloalkane oil have good dispersibility and compatibility. But its processing cost is relatively high, so the price of insoluble sulfur for radial tire sulfur is also correspondingly high.
Firstly, the flash point should be higher than 160 degrees, with good low-temperature fluidity and thermal stability. The color should be light, and the lower the alkaline nitrogen content, the better. In order to stabilize the price of insoluble sulfur for oil filling, ordinary aromatic oil is often used for sulfur filling oil nowadays. The fatty hydrocarbons between them are dehydrogenated and cyclized into aromatic hydrocarbons such as benzene through Pt Re catalysts, and then aromatic products are extracted from them. This aromatic oil contains certain impurities and alkaline substances, which have a significant impact on the stability of insoluble sulfur when used as a sulfurizing agent to increase oil content. In order to ensure the stability of oil filled insoluble sulfur during storage at room temperature, its dispersibility in rubber, heat resistance, and conversion resistance, the composition of the oil can be adjusted, and appropriate control agents can be added to stabilize and neutralize impurities and alkaline substances. The sulfurizing agent is loose, non spherical, and non flying.
Oil filled sulfur powder is a commonly used vulcanizing agent for natural rubber vulcanization, with a long history since the development of the rubber industry. The fracture elongation is high, but the thermal oxidation aging performance is poor. Therefore, it is necessary to use appropriate accelerators. It should be noted that the addition of oil filled sulfur powder and the increase of the dosage of various additives in the vulcanization system can improve the tensile strength, tensile stress, hardness, and tear strength of natural rubber vulcanizates. When the sulfur content is high, the aging resistance of vulcanizates is good. Distinguishing the use of calcium carbonate as a filler in natural rubber is a very good method to reduce costs and increase product volume.
When oil filled sulfur powder is used as a vulcanizing agent, natural rubber is filled with calcium carbonate, and generally accelerator M and accelerator DM are added. If it is a light colored natural rubber product, a small amount of autumn blue accelerator can be added to improve the effective crosslinking density and good mechanical properties of the vulcanized rubber. Natural rubber and calcium carbonate are used in combination with accelerator CZ/DM, accelerator CZ/TMTD, and accelerator NS/TMTD. The vulcanization speed is fast, and the tensile strength, tear strength, and aging resistance of vulcanized rubber are high. However, attention should be paid to the application of calcium carbonate. If the dosage is not appropriate, the elasticity, strength, and viscosity of natural rubber products are easily reduced. In addition to filling with calcium carbonate, the way to reduce the cost of natural rubber application is to use recycled rubber in an appropriate amount. While ensuring product quality, it can effectively reduce raw material costs.