First, the cause of burning and treatment of mixed rubber
1. Mismatches
Such as vulcanizing agent, accelerator dosage is too much;


2. Improper rubber mixing operation
Such as the temperature of the rubber mixer is too high, the cooling device is not good, or premature addition of sulfur, or the local high concentration of vulcanizing agents and accelerators caused by uneven dispersion, or premature rolling without heat dissipation, or the volume is too large, or the film is not sufficiently cooled;


3. Improper parking
Including glue storage for too long, the temperature of the parking place is too high, or the air is not circulated, or the hot chain is stacked for too long.


Second, prevent scorch
The general dosage of anti-coke agent should not exceed 0.4 parts, adding before vulcanizing agent and accelerator.
Method to prevent burning of mixing glue in mixer
The burning of the mixer mixing rubber is more common at the beginning of the Meiyu season. Thanks to the Mooney viscometer and vulcanizer, both new and returned compounds can be measured at any time, thus preventing the scorch of the compound. In the mixer factory that produces large quantities of mixed rubber, it is not necessary to carry out comprehensive determination, and only one determination method can be used for the rubber material that is specified to be paid attention to.


The following describes how to prevent scorch
First of all, 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, the use of vulcanization accelerator alone is rarely, mostly the use of two, three kinds of accelerators and the way. Once there is a problem with the combination, it can not prevent the burning of the rubber, in general, the main accelerator for general rubber is the exposure pill or sulfophthalamine accelerator. The main accelerator DM is a universal accelerator. The accelerator M has a high scorch resistance, and the secondary sulfonphthalamine accelerator has a scorch resistance, but due to the slow start speed of vulcanization, it is necessary to choose according to the requirements of the use of rubber material. Muscle and Thiuram are auxiliary accelerators. In the high temperature season of summer, the auxiliary accelerator should be used in a reduced amount, while the main accelerator should try not to reduce its coordination amount.


Adding 10-20 mass recycled rubber into general purpose rubber, the rubber compound made after blending has the effect of preventing scorch. In addition, for the blend, we should consider the design of additive formula, and make some necessary corrections on the basis of studying the scorch property and the physical properties of vulcanizate. In the white carbon black material, it is necessary to add diethylene glycol, polyethylene glycol, organic amine promoter SL and so on. However, excessive addition of the above additives will also lead to scorch, so it must be paid attention to. The standard dosage should be (compared to silica) 60% diethylene glycol with polyethylene glycol (molecular weight 400) and 2.5% organic amine accelerator SL.


In terms of coordination, although many discussions have been made as described above, if the scorch cannot be prevented, an anti-scorch agent (vulcanization delay agent) can be added. The curing retarder is an organic synthetic compound of anhydrous phthalic acid and benzoic acid, nitroso compound and phthalphthalamine. Nitrosodiphenylamine can not be used for light-colored rubber products because of its polluting properties.


While delaying vulcanization, the anticoke agent also slows down the vulcanization rate, because it will reduce the degree of crosslinking, so do not use a lot. As a rule of thumb, the dosage should not exceed 0.4%. If it must exceed 0.4%, the amount of vulcanization accelerator should first be reduced. It is not appropriate to use the combination method of high accelerator and high anti-coke agent.


The problems that should be paid attention to to prevent coke burning are introduced. For each batch of mixing compound, the range of coke burning time is set on the basis of the original data, and the solution is adjusted continuously within this range. For example, set the Mooney scorch time to 125 ° C


The film can be cooled to room temperature by water cooling, air cooling or a combination of both. Even the rolled and rolled rubber material, if there is a risk of burning, it can be air cooled while winding, or cut according to a certain length and then air cooled. According to the need, it can also be stored in air-conditioned rooms and cold storage.


For most of the rubber material that needs to be returned, first put the rubber material that needs to be returned into the hot smelting machine. After confirming that the rubber material has not been scorched, a new mixing rubber is added for mixing. If the operating procedure is contrary to this, it will cause all the rubber material of the mixing machine to scorch.




Third, deal with scorch
Thin pass in the opening mill, and the roller temperature is low, the filling capacity should be small, can not wrap the roll, pack, roll, park for 24 hours, and then use in the good material, adding 15-20%. Stearic acid and oil softener are added during thin opening to break down the crosslinked structure.