Butyl rubber synthesized from isobutene and a small amount of isoprene has excellent air tightness, water tightness, chemical stability and thermal stability. It is widely used in the preparation of various tube, steam pipe, water tube, dam bottom, gasket and other products. When using butyl rubber to produce rubber products, due to the large cold flow of butyl rubber, the stiffness of semi-finished products is relatively poor, easy to deform, the mixing agent is not easy to disperse, and the roll wrapping property is poor; therefore, it is necessary to strictly control the mixing process.
1. Pay attention to the cleanliness of the equipment before mixing
When butyl rubber is mixed, other rubber or impurities are mixed in the mixing equipment, especially the rubber with high unsaturation degree, which directly affects the quality of rubber compound. In serious cases, the finished products of butyl rubber products will be scrapped directly. Therefore, the mixing equipment must be cleaned before mixing butyl rubber, and the mixing equipment must be checked and maintained regularly and timely during normal use.
2. Pay attention to mixing process conditions
Butyl rubber itself has low cohesion, poor self-adhesive, the rubber is easy to break, and the process of re coalescence is very slow, so it needs higher mixing temperature and longer mixing time. In the mixing process, 2ylyy114 should pay attention to the change of mixing temperature in time and strictly control the mixing temperature to avoid the influence of too high or too low temperature on the quality of rubber mixture and finished product. In actual production, when butyl rubber is mixed in internal mixer, the mixing temperature is generally controlled at 150 ℃ to promote the uniform dispersion of the compounding agent.
3. Key points for mixing with different rubber mixers
(1) Mixing in open mixer: when mixing butyl rubber in open mixer, the problem of poor performance of butyl rubber roll can be overcome by using the method of feeding (i.e. adding rubber and compounding agent after feeding rubber roll). In the feeding process, slow feeding is adopted in batches. Firstly, half of the raw rubber in the formula is thinned repeatedly with small roll gap, and the other half of the raw rubber is added after roll wrapping to improve the mixing effect. The temperature of the front roll should be 15-20 ℃ lower than that of the back roll in order to adapt to the performance of the cooling roll.
(2) Mixing in internal mixer: when using internal mixer to mix butyl rubber, the rubber loading capacity should be increased appropriately, and the general capacity is greater than 10% - 20% of natural rubber; when mixing, the top bolt pressure is higher than the bottom bolt pressure. When the amount of compounding agent used in the formula of butyl rubber products is large, two-stage mixing method or reverse mixing method can be used for mixing process.
At present, many butyl rubber products use butyl reclaimed rubber in the production process. Compared with butyl rubber, the mixing process performance of reclaimed rubber is better. Rubber product manufacturers need to mix with butyl reclaimed rubber after butyl rubber is fully plasticized. Later, Xiaobian will continue to discuss the mixing process points of butyl rubber / reclaimed rubber with you.
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