At present, the main plasticizing is unsaturated natural rubber and hard nitrile rubber. For EPDM, butyl, neoprene, cis-butadiene and acrylate adhesives, if they are used for molded products, they do not need to be masticated and can be directly mixed. But for calendered, extruded and sponge products, in order to ensure that the shrinkage rate of the product is small and the surface of the product is smooth, even if the raw rubber can be mixed without mastication, multi-stage mastication should be carried out to improve the plasticity of the raw rubber. Produce qualified products. In recent years, soft butadiene rubber imported from abroad, such as Japanese nitrile 240S, Russia's CKH-26, etc., has a low Mooney viscosity value. Generally, it is not necessary to carry out mastication, but to carry out kneading directly.
1. Main points of Dingqing reclaimed rubber plasticizing process
The plasticizing process of nitrile reclaimed rubber generally adopts low-temperature thin-pass method and segmented plasticizing method. The surface of plasticized reclaimed rubber is smooth and shiny, and the surface has no holes after wrapping. Factors such as loading capacity and operating proficiency will affect the plasticizing effect of nitrile reclaimed rubber.
(1) The lower the roll temperature, the better the plasticizing effect. However, the cooling of the roller is limited by various objective reasons, and the ideal effect cannot be fully achieved; it is recommended to use the segmented plasticizing method or the cold air circulation climbing device to speed up the cooling of the film and improve the plasticizing effect.
(2) The smaller the roll distance, the better the plasticizing effect. The shearing force of raw rubber is large, and the macromolecules of rubber are rapidly degraded; the thinner the film, the faster the heat is emitted, which is very beneficial to plasticizing. Generally, compared with the roller distance of 0.5mm and the roller distance of 1mm, the small roller distance has better plasticizing quality; from the point of view of efficiency, the larger the roller distance, the longer the plasticizing time, about 10 minutes.
(3) The amount of glue loaded affects the plasticizing effect of raw rubber. With more glue, the raw rubber passes through the gap for a long time. In the same masticating time, the plasticizing effect with a small amount of glue is better than that with a large amount of glue. If the amount of glue loaded is too much, it is very easy to "trip" when the equipment is overloaded, which increases the risk of damage to the equipment; the plasticizing time is prolonged, the labor intensity is increased, and the quality of Dingqing reclaimed rubber plasticizing is not good. Generally, the loading amount of synthetic rubber is 20% less than that of natural rubber.
2. Key points of Dingqing reclaimed rubber mixing process
Mixing is an important process in the production process of Dingqing recycled rubber products. The quality of the mixed rubber directly affects the quality of the finished product. The following points should be paid attention to when mixing: ① All kinds of compounding agents with small dosage but great effect should be Mix thoroughly and evenly, otherwise it will cause scorch or undercooked vulcanization of the rubber. ②Mixing should be carried out in strict accordance with the mixing process regulations and the feeding sequence. ③ The mixing time should be strictly controlled, and the time should not be too long or too short. Only in this way can the plasticity of the mixed rubber be guaranteed. ④ Do not throw away the large amount of carbon black and filler to use up, and clean the material tray.
The quality problems that are prone to occur during the mixing of nitrile rubber mainly include uneven dispersion of compounding agents, frost spray, scorch, etc. Improper formulation design, improper dosing sequence, uneven mixing, etc. will cause the above problems. You share the key points and specific precautions of the nitrile regeneration and mixing process.
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