The rubber mixing process is essentially a process in which the compounding agent is uniformly dispersed in the raw rubber, the granular compounding agent is in a dispersed phase, and the raw rubber is in a continuous phase. During the mixing process, the molecular structure, molecular weight and distribution of the rubber, and the aggregation state of the compounding agent all changed. Mixing Introduction Mixing is a process in which raw rubber or plasticized raw rubber and compounding agent are refined into a rubber compound by a rubber mixing machine, which is the most important production process for rubber processing.
The mixing can be carried out using an open mill, an internal mixer and a screw continuous mixer. When mixing with an open mill, manual operation is required, labor intensity is high, and it is not safe. The mixing operation with the mixer is safe and the labor intensity is small, which is the most common application at present. The mixing requires that the compounding agent be uniformly dispersed in the raw rubber to form a colloidal dispersion, so that the vulcanized rubber has the best performance. At the same time, there are certain requirements on the plasticity of the compounding compound, so that it can meet the requirements of the post-process. There is a one-stage and two-stage mixing method. The former is to gradually add a compounding agent to the rubber. The latter is to first add the softener and the powder filler to carry out the first stage of the crude mixing. After the rubber is cooled and left for a certain period of time, the second stage is mixed with the sulfur and the accelerator.
Rubber (green rubber) and various compounding agents (see rubber) are mixed in a rubber processing machine. In order to be able to add the powdery compounding agent to the rubber, the raw rubber must first be plasticized to improve its plasticity and fluidity. The mixing process is the most basic process of rubber processing. The quality of the compounded compound after adding the compounding agent has a decisive influence on the process performance and finished product quality of the semi-finished product.
In the rubber mixing process, the rubber mixing process is essentially a process in which the compounding agent is uniformly dispersed in the raw rubber. The granular compounding agent is in a dispersed phase, and the raw rubber is in a continuous phase. During the mixing process, the molecular structure, molecular weight and distribution of the rubber, and the aggregation state of the compounding agent all changed. Through mixing, rubber and compounding agents play a physical and chemical role, forming a new structure. A rubber compound is a dispersion system with complex structural characteristics. Due to the high viscosity of the raw rubber, in order to allow the compounding agent to penetrate into the raw rubber and uniformly mix and disperse therein, it is necessary to rely on the strong mechanical shearing action of the rubber mixer. The mixing process will vary depending on the type of mixer used. The rubber mixing machine mainly has two types: open type and closed type. The newer mixers are screw-transfer devices that save energy and floor space, reduce labor intensity, and facilitate continuous production.
The rubber of the open type rubber mixing machine is repeatedly subjected to shearing in the gap between the two rotating rolls of the open type rubber mixing machine (see color picture), and is controlled by manual operation. It mainly consists of three stages: 1 raw rubber heating. The raw rubber that has been plasticized is re-refined on the machine, softened by heating, and blended with other polymers. 2 plus compounding agent. Generally, a softener, stearic acid, etc. are added first, and then a powder and carbon black are added (carbon black can also be separately mixed with a raw rubber as a masterbatch in advance). Sulfur is usually added at the end of the mixing or after the second re-refining of the compound. 3 mix evenly and the next piece. Once all the ingredients have been added, continue to re-mix to evenly mix and remove the film. Closed rubber mixer mixing process The size of the gap between the rotor surface of the closed rubber mixer (see color picture) and the wall of the mixing chamber varies greatly with the rotation of the rotor, resulting in strong shear to the rubber compound. effect. The mixing effect is much larger than that of the open type rubber mixing machine. The various powder compounding agents are mixed in the mixing chamber and the rubber compound without flying, and the automatic meter controls the mixing process, for example, during the mixing process, the temperature of the rubber compound. There is a certain regularity in the volume of the material in the room and the power consumption.
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