It is estimated that about 20 million tons of waste rubber tires will be produced in China this year. Processing recycled rubber is the main way to deal with waste tires in China. Expanding the application scope of recycled rubber in rubber products industry is of great significance to solve the pollution problem of waste tires. When using recycled tire rubber to produce rubber products, the scorch time directly affects the processing process of the products, and ultimately affects the performance and life of rubber products. Manufacturers need to take appropriate measures to control the impact of scorching time on the production process of tire reclaimed rubber products.
1. Definition of scorch time
The so-called scorch time is the time required for torque to reach 10%, which can also be called safe operation time. It can be divided into theoretical scorching time and residual scorching time to measure the difficulty of scorching. The theoretical scorch time is determined by the vulcanization system and curing temperature; the scorch time will be reduced in the process of repeated turning, mechanical force or parking, that is, the residual scorch time. The main factors affecting the scorch time are the rubber formula and the storage time.
2. The influence of scorch time on the production of recycled tire rubber products
Scorch is an early vulcanization phenomenon in rubber processing. When using recycled tire rubber to produce rubber products, the longer the scorch time is, the lower the probability of early vulcanization; on the contrary, the shorter the scorch time, the more likely it is to cause scorch. In the actual production, the manufacturer of recycled tire rubber products can determine the scorch time of recycled rubber by Mooney viscometer.
3. How to control the scorch time of reclaimed rubber
There are two main factors affecting the scorch time of reclaimed tire rubber: formulation and process conditions. The control of scorching time of reclaimed tire rubber can be started from these two aspects.
(1) Product formula: when using recycled tire rubber to produce rubber products, accelerator with high retardation or critical temperature, such as nobs, can be used in the curing system. If necessary, CTP or fatty acid can be used to prolong the scorch time and effectively prevent scorching. The heat generated during the processing of recycled tire rubber products will cause scorch. The probability of such scorching can be reduced by using rubber oil or resin appropriately in the formulation of rubber products.
(2) Production process: strictly control the mixing temperature and vulcanization temperature of recycled tire rubber, prolong the scorching time of rubber compound and avoid scorching.
When using recycled tire rubber to produce rubber products, the compound with vulcanization system will generate heat during processing, and the vulcanization system will start to work. Rubber product manufacturers need to take measures to appropriately extend the safety time without affecting the normal production efficiency, effectively prevent the compound from burning to death, and improve the comprehensive performance of tire reclaimed rubber products.
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