Treatment of burnt rubber
(a) Treatment of burnt rubber:
(1) For the slight degree of scorching:
Rubber into the open refiner rolling thin pass, the beginning of the roll distance can be a little too much, and then adjust the roll distance down to 0.5 ~ 1.5 mm. At the same time add l ~ 3 parts of stearic acid. At this time, the roll temperature should be controlled below 45 ℃, loaded with less rubber capacity, for the conventional mixing rubber capacity of 1/2, the operation process can be used directly down the disc way rolling, film does not have to wrap the roller, every 5 times through the thin pass for a stage, on the light burning of the rubber, thin pass through a stage or two or three stages that is completed. Parked for 24 hours, can be mixed into the normal rubber to use.

(2) For slightly heavier degree of burning:
At this time there are a small number of cooked rubber particles in the rubber, but the area is not large, the rubber particles are small, the film can be rolled in the open refiner on the thin pass, roll temperature and roll distance and the same operation as the above. In the thin pass rolling to add plasticiser zinc salt of pentachlorothiophene 2 parts a 3 parts, rolling 5 minutes, and then add the softener. Light or coloured rubber, can add a small amount of rosin or terpene resin; black rubber can be mixed with pine tar. Make the rubber material softening, adding about 5 to l0 parts, so that the mixing is uniform. Thin through after the next piece. This rubber can be mixed into the normal use of rubber in the application, but the amount of mixing should not be too much. About 5 ~ 10 of the normal rubber that can be.

(3) The degree of scorching is more serious:
Synthetic rubber such as nitrile rubber. Sleepy rolling heat, nitrile rubber and harder and tougher. It is easy to burn when mixing. Especially when there are more fillers. At this time the rubber can be scorched into the open refiner rolling, thin through the case as mentioned above, but not only to add the plasticiser Pentachlorothiophenol zinc salt, but also to join the activator 420. usually add Pentachlorothiophenol zinc salt 2 parts and activator 420 about l part. The chemical name of the activator 420 is 2,2 dithiobis (tert-butylated p-cresol), which is a commonly used activator in the production of recycled rubber). Add the zinc salt of pentachlorothiophenol rolling 2 to 3 minutes, and then add the activator 420 rolling 3 minutes, and then thin pass, add the softener liquid Gumarone resin, or pine tar. Or dibutyl phthalate (for butyl rubber). Plasticised and softened scorched rubber can be mixed into the normal use of the production rubber. In order to ensure that the quality is not affected, the amount added should not be too much, generally can be added to the above glue about 5 parts.

 (ii) in the production process to prevent burning:
The following measures should be taken to prevent scorching in the production process:
1. the raw materials should be weighed accurately, especially the amount of accelerant and vulcanising agent should be weighed accurately, avoiding scale failure or weighing error the various accelerants should be clearly identified, do not get it wrong. 2. the chemicals should be added when mixing.
2. The order of adding chemicals should be correct when mixing, usually the order of mixing and adding materials is as follows:
Raw rubber, zinc chloride, stearic acid, an antioxidant, a reinforcing agent and oil softener alternately added in turn, a sulfur, an accelerator, a rubber under the sheet.
Do not roll at higher temperatures, the addition order is reversed, the accelerator added at the last stage, which is safer.
3. When the accelerator and vulcanising agent are added, they should be added in several batches, and the amount added in each batch should be small, and should be evenly distributed. Avoid concentrating on local areas, resulting in scorching
4. the roller temperature should be strictly controlled, or the temperature of the refining room. Strengthen the cooling water circulation, accelerate cooling. The use of lower-temperature deep well water cooling, the effect is better at the same time should also be stored in the lower temperature of the rubber material placed in the place, do not close to the warmth of the heat flow or direct exposure to sunlight.