Due to the high Mooney viscosity and high mechanical strength of latex reclaimed rubber, it is easy to mix and difficult to mix without mastication. Therefore, latex reclaimed rubber must be masticated before mixing in order to obtain a suitable degree of plasticity.
Because latex regenerated rubber is crystalline rubber, especially in winter, if the crystallization is not removed, it will bring great difficulties to rubber cutting and damage equipment. Therefore, the glue should be baked before cutting the glue. The rubber drying is generally carried out in the rubber drying room, the temperature is about 60°C, and the time is preferably 48 hours.
After the latex reclaimed rubber is taken out from the drying room, first remove the impurities on the surface of the latex reclaimed rubber, and then use a rubber cutter to cut it into small pieces of about 5 kg for later use. It is best to separate the glue blocks with a release agent to avoid sticking to each other and keep them clean. The cut rubber blocks need to be broken, which is usually done on the rubber mixer in the factory. Taking the 14-inch rubber mixing machine as an example, first narrow the baffle (the working surface accounts for about 2/3 of the length of the roller), and adjust the roller distance (0.5㎜) to prevent the rubber mixing machine from being overloaded and causing " trip" and damage the equipment. Then put the rubber blocks into the rubber mixer one by one by the end of the large toothed wheel, and the amount of glue is about 20 kg. When loading glue, you should face the rubber mixer sideways or stand on the side of the rubber mixer to prevent the glue from popping out and hurting people, and at the same time turn on the cooling water. Broken latex reclaimed rubber should be masticated in time, and should not be parked for a long time. Because after a long time of parking, the latex reclaimed rubber will stick together again, and it is troublesome to cut and break the glue again(23YY508).
Put the latex reclaimed rubber into the open mixer during plastication, let it fall directly into the material tray through the roller distance, do not cover the rollers and repeat it, the time is about 30 minutes, and the roller temperature is controlled at 50 ℃ the following. If the temperature is too high, the phenomenon of false plasticity will appear (once the plasticized rubber cools, the phenomenon of recovery will occur again). In order to avoid this phenomenon, the lower the temperature of the roller, the better. At the same time, the increase of mechanical shear force is conducive to the degradation of rubber macromolecules, so as to obtain the effect of mastication.
In the first 5 minutes after mastication started, the mastication effect of latex reclaimed rubber was very obvious. The increase in plasticity slows down over time. If you stop mixing at this time, it will be quickly reflected when you mix again: the plasticized rubber is not easy to wrap the roll, even if it is wrapped, the surface is not smooth, and the powder cannot be added. At this time, the masticated rubber should be re-thinned and masticated until a satisfactory effect is obtained.
From the above situation, despite the continuous extension of time, the plasticity increase of latex reclaimed rubber is not as effective as in the first 5 minutes. But it does not mean that it is enough to masticate for only 5 minutes. On the contrary, subsequent training is very necessary. Otherwise, it will increase the labor intensity and prolong the mixing time during mixing, and the quality of the mixed rubber cannot be guaranteed.
The degree of plastication and the quality can be observed by the naked eye. The surface of the plasticized latex reclaimed rubber is smooth and translucent. At this time, the latex reclaimed rubber has basically reached the plasticity. If you are not experienced enough, you can also relax the roll distance (2-3mm) to wrap it around the front roll. If the surface of latex reclaimed rubber is not smooth, it means that the mastication is not enough. If the surface is smooth, it means that the mastication is good. If the mastication is not enough, it has to be re-melted until a satisfactory mastication effect is obtained.
Relax the plasticized latex reclaimed rubber roll distance to 2~3mm for the next piece. The film is 80 cm long, 40 cm wide, and 0.4 cm thick. Allow to cool naturally, and then use the spacer. It is also possible to directly use the weighing scale to weigh the required quantity of the mixed rubber with the finished film. Plasticized latex reclaimed rubber is generally used after being parked for 12 hours.
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