Natural rubber is widely used in the production of various rubber products due to its excellent elasticity, abrasion resistance and tear resistance. When using natural rubber as the main raw material to produce rubber products, the choice of vulcanization system is crucial. Vulcanization can not only enhance the mechanical properties of natural rubber, but also improve its heat resistance, aging resistance and chemical stability. The most commonly used vulcanization systems for natural rubber are sulfur vulcanization systems, including ordinary sulfur vulcanization systems, semi-available sulfur vulcanization systems and available sulfur vulcanization systems
1. Ordinary sulfur vulcanization system
The ordinary sulfur vulcanization system is the most commonly used vulcanization method for natural rubber, which is achieved by a high proportion of sulfur and a low proportion of accelerators, and the cross-linked bonds are mainly polysulfide bonds. When natural rubber chooses ordinary sulfur vulcanization system, vulcanized rubber has good physical and mechanical properties, such as high strength, high elasticity and high wear resistance; Vulcanized rubber has poor heat resistance and aging resistance, and is prone to return to its original phenomenon during the vulcanization process.
When natural rubber produces soft rubber products, the dosage of sulfur is usually 2-3.5 parts, and the standard dosage is 2.75 parts. Insoluble sulfur can be used when the amount of sulfur is large to reduce the risk of sulfur spraying and burning. Natural rubber adopts ordinary sulfur vulcanization system, and the classic combination (mass content) is S/M (DM) 3.0/0.7, S/M 3.5/0.5, S/CZ 3.5/0.5, S/TBBS(NS) 2.25 (3.5)/0.7, S/DM/D 2.5/1.2/0.4, S/NS (CZ)/TT(TS) 2.5/0.6/0.4, etc.
2. Effective sulfur vulcanization system
There are two types of effective sulfur vulcanization system: high-promotion and low-sulfur combination and sulfur-free combination. A higher proportion of accelerator (2-5 parts) and a lower proportion of sulfur (about 0.5 parts) are used for high-promote-low sulfur combinations, while sulfur-free combinations are used for thiosol-feeding bodies such as TMTD or DTDM. The cross-linked bonds generated by this system are mainly monosulfide bonds, and the natural rubber vulcanized rubber has excellent heat aging resistance, and there is no vulcanization regression phenomenon after sulfurization. However, when TMTD vulcanization is used alone, it is less safe to operate, easy to scorch, and heavily frosted.
In actual production, natural rubber products require high-temperature vulcanization without returning, high temperature resistance and good aging resistance, and it is advisable to use an effective sulfur vulcanization system.
3. Semi-available sulfur vulcanization system
The semi-available sulfur vulcanization system is among the ordinary sulfur vulcanization system and the available sulfur vulcanization system. It is vulcanized by a medium sulfur dosage (1-1.7 parts) and accelerator dosage (1.2-2.5 parts). The cross-linked bonds of this system include both polysulfide bonds and monosulfide and disulfide bonds, so the vulcanized rubber has many characteristics such as heat resistance, fatigue resistance and sulfur regression resistance. The commonly used combinations of natural rubber semi-available sulfur vulcanization system are S/NS 1.5/1.5, S/NS/DTDM 1.5/0.6/0.6, etc.
When choosing the vulcanization system of natural rubber products, it is necessary to comprehensively consider the performance requirements, cost, processing technology and safety of the product. Different vulcanization systems provide different properties E4LYY315 characteristics, such as heat resistance, aging resistance, regression resistance, etc. In actual production, natural rubber can also be made of esters, maleimides and organic peroxide vulcanization systems. By properly selecting and adjusting the vulcanization system, the performance of natural rubber products can be optimized, especially when using reclaimed rubber to reduce costs and meet the needs of various applications.
The price of natural rubber on the market is high and fluctuates greatly, so many manufacturers have begun to use sub-brand natural rubber and natural latex recycled rubber to replace all or part of the rubber production products to reduce costs; At this time, the vulcanization system needs to be adjusted to a certain extent, and the follow-up editor will continue to share with you the key points of the vulcanization system design when natural rubber uses low-cost option raw materials.
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