Mixing is one of the main processes in the production process of reclaimed rubber products, which is the process of refining raw rubber or plastic raw rubber with compounding agent into rubber compound with a rubber mixer, the purpose is to make the compounding agent evenly dispersed in the raw rubber, so that the rubber material has appropriate plasticity to ensure the smooth processing. The reclaimed rubber mixing process can be divided into open mixer mixing and internal mixer mixing according to the rubber mixing equipment. The process operation process and key points of attention of different rubber mixing methods are very different.
1. Reclaimed rubber is mixed using an open mill
The mixing machine can be divided into one stage mixing and two stages of mixing, and the reclaimed rubber can be used when the rubber content is high or only a small amount of natural rubber and synthetic rubber can be used in combination; When a variety of rubbers are used together and the amount of reinforcing agent is large, it is recommended to use two-stage mixing to make two or more rubbers and compounding agents more uniform. The mixing process of the open mill is divided into three stages: roll wrapping, powder eating and refining.
(1) The roll is the premise of the mixing of the open mill; For rubber compounds with poor roll wrapping properties, adding part of the carbon black first can improve the roll-off phenomenon; In the event of derolling, in addition to reducing the roll temperature, the reclaimed rubber can also be rewrapped by reducing the roll distance, increasing the speed or increasing the speed ratio.
(2) Powder eating is the second stage of mixing in the open mill, and the process of mixing the compounding agent into the rubber material is the powder eating stage. In the process of eating powder, the amount of glue must be moderate. In the process of eating powder, the amount of glue should be controlled HYL6Y5YEEWFM, and its height should not exceed the range of contact angle (the contact angle is generally 32-45°); If the accumulation glue is too small, the added powder is not easy to be rubbed into the rubber, and even will be pressed into thin sheets by the roller and fall on the chassis; When it is too large, the reclaimed rubber rubber rolls, and the powder is not easy to mix.
(3) Refining is the third stage of the mixer mixing, which must go through many times of refining, left and right cutters, rolling or triangular bags, thin passes, etc., to destroy the dead layer and reflux area, so that the reclaimed rubber is mixed uniformly, and the texture of the reclaimed rubber compound is uniform.
2. Reclaimed rubber is mixed using an internal mixer
When the reclaimed rubber is mixed with an internal mixer, the mixing process is carried out under fast, high temperature and high pressure conditions. In actual production, the internal mixer uses the shear force generated by the regular contraction of space generated by the relative movement of the impeller that has been designed internally. Because the work of the internal mixer is regular, it is more suitable for the uniform mixing of reclaimed rubber in the rubber compound to ensure the uniformity of mixing, so the rubber mixed with reclaimed rubber is more suitable for mixing rubber with the internal mixer.
It should be noted that because the mixing temperature is difficult to control during the mixing in the internal mixer, it is easy to scorch; Therefore, it is not suitable for mixing temperature-sensitive rubber compounds, light-colored rubber compounds, special rubber compounds and rubber compounds with frequent variety changes. The mixing operation of reclaimed rubber in the internal mixer should be done lightly, slowly lower thallium, full pressure, and not grab points, especially in the reclaimed rubber with many fillers, it should not be added too quickly; The scattered chemicals in the operation should be collected and cleaned up in time, and the extruded or scattered rubber materials and the chemicals should be cleaned and mixed in the same kind of rubber materials, and attention must be paid to keeping them clean and not allowed to mix with sundries.
Mixing is an important process in the production process of reclaimed rubber products, the quality of reclaimed rubber compounding directly affects the quality of finished products of reclaimed rubber products, rubber products manufacturers must determine the appropriate mixing process according to the actual needs of products, equipment conditions, etc., to lay a better foundation for subsequent process operations; In the later stage, Xiaobian will continue to share with you the process skills related to reclaimed rubber mixing.
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