Vulcanization is the process of transforming plastic rubber into elastic vulcanized rubber to obtain better physical and mechanical properties and chemical properties. The rubber vulcanization process can be divided into four stages: vulcanization induction, pre-sulfur, positive vulcanization and over-sulfur.

Scorch is a phenomenon of early vulcanization of the rubber material during storage or operation. When designing a reclaimed rubber product formulation, it is necessary to ensure the shortest vulcanization time at the specified vulcanization temperature and the longest scorching time at the processing temperature.

1.recycled rubber products commonly used accelerator own scorching performance
When designing the vulcanization system of recycled rubber products, the first thing to consider is the scorching performance of the accelerator itself. The structure contains anti-coke functional groups (-SS-, etc.) auxiliary anti-coke groups (such as carboxyl, sulfonyl, phosphoryl, phosphorothioyl and benzothiazolyl) of the accelerator itself good scorching performance.

In actual production, the coking time of various accelerators from short to long is: ZDC < TMTD < M < DM < CZ < NS < NOBS < DZ.

2. How to prevent the scorching of recycled rubber by adjusting the accelerator
When using recycled rubber to produce rubber products, the role of different varieties of accelerators in the recycled rubber depends on its critical temperature.

(1) accelerator TMTD is a common accelerator in the vulcanization system of recycled rubber, its induction period is very short, which can make the rubber material fast vulcanization. TMTD can be used in the vulcanization system of recycled rubber products with secondary sulfonamide type HYL29Y9YEE accelerator (such as accelerator CZ), thiazole type accelerator (such as accelerator DM), which can effectively prevent scorching of the rubber material.
(2) When using the promoter of Tyuram alone, the scorching time of the recycled rubber is relatively short even if no or less sulfur yellow is added, so it is recommended to reduce the dosage of Tyuram promoter with sub-sulfonamide or thiazole promoter at the same time to prolong the scorching time.
(3) guanidine accelerator (such as accelerator D) has high thermal stability, as its main accelerator, the scorching time of the regenerated rubber material is long and the vulcanization speed is slow.
(4) Butyl recycled rubber products are commonly used in the production of dithiocarbamate accelerators; it should be noted that this type of accelerator will sharply shorten the scorching time of unsaturated rubber; with guanidine accelerator, the scorching time will be further shortened.
(5) alone using latex rubber, tire rubber, or with natural rubber, vulcanization system using thiazole accelerator, hyposulfenamide accelerator, adding a small amount of accelerator DTDM can significantly improve the anti-scorching performance of recycled rubber.