Coking is essentially the accumulation of the influence of heat and time on the rubber material in the process of technology, and is the early vulcanization phenomenon of rubber material, which can also be called the thermal process of rubber material. The coking time is often used to measure the difficulty of the coking of the rubber material. The longer the coking time is, the less likely the phenomenon of early vulcanization occurs in the processing process. The burning time can usually be measured with a Mooney viscometer. If the thermal process of the compound is longer and the temperature is higher, the coking time of the compound can be shortened gradually.

1.how to judge rubber coke?

In the smelting of rubber, if the film is found to be granular or the rubber is found to be elastic or crepe, it is a prelude to coke.

（1）. Burnt rubber, vulcanized products are not bright (mist), the surface has obvious wrinkles, the surface is uneven, and it is brittle and easy to crack.
（2）. The surface of burnt glue is uneven and hard. And the scissors kept burning the glue.
（3）, coke burning glue by doing Mooney coke burning test can be measured.
（4）. See figure: there are bulges in the burnt part. Try cutting. Even scissors can cut hard.

2. the prevention of coke method

（1）. The formula design of auxiliary agent of rubber material should be appropriate and reasonable. In order to adapt to high temperature, high pressure and high speed rubber refining process, appropriate amount (0.3-0.5) of anti-coke agent can be used as far as possible. Can also reduce the amount of vulcanization accelerator, but this will lead to a decline in the physical properties of rubber products, it is very important to understand this, vulcanization accelerator alone is rarely used, mostly by two or three kinds of accelerator and the way. Once the problem is matched, it can not prevent the coke of the rubber. In general, the main accelerator for general rubber is the sulfonphthalamide accelerator. The main accelerator DM is a universal accelerator. Accelerant M has high scorchability. Although subsulfonphthalamide accelerant has scorchability, it should be selected according to the requirements of rubber material because of the slow starting speed of vulcanization. Chulam is an auxiliary accelerator. In the summer high temperature season, the auxiliary accelerant should be used less, while the main accelerant should not reduce its coordination amount as far as possible.
（2）, for the cooling measures of rubber material, through strict control of machine temperature, roll temperature and sufficient cooling water circulation, so that the operating temperature does not exceed the critical point of coke.
（3）. The management of rubber semi-finished products ensures that each batch of materials is followed by a flow card, follows the principle of "first-in, first-out" storage, and stipulates that the longest storage time of each truck of materials does not exceed. In addition, keep the warehouse well ventilated.