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Rubber Mixing Technique

Qingdao Steady Machinery Co.,Ltd | Updated: Aug 20, 2015

The main reason for the mix of materials generated during placement "from sulfur" is:


(1) a vulcanizing agent used to promote too many agents;

(2) mounted plastic high-capacity, high temperature mixing machine, film cooling is not enough;

(3) premature vulcanization, drug material dispersed or caused by uneven local concentration of accelerator and sulfur;

(4) improper parking, parking spaces ie temperature, ventilation and so on.


How to reduce rubber compound Mooney?


Of rubber mix Mooney M (1 + 4), i.e., 100 degrees in one minute preheat, 4 minutes rotor rotational torque of the size, i.e. the size of the rotation of the rotor is hindered force. Those who can reduce the force rotation of the rotor can be reduced Mooney, formulation of raw materials including gum: natural rubber and synthetic rubber, natural rubber Mooney select low or the addition of chemical peptizer to natural rubber formulation (physical plasticizer ineffective) is a good choice, synthetic rubber is generally not add peptizers, you can usually add some lipid-called low molecular weight dispersant or internal mold release agents and the like, such as strict requirements for hardness, then of course you can also increase stearic acid or oil class component; if the process can be improved ram pressure or an appropriate increase in discharge temperature, if the conditions allow to reduce the temperature of the cooling water may also reduce rubber compound Mooney.


Factors Affecting mixer mixing effect


Mixer mixing compared with the open mill mixing with kneading time is short, high efficiency, high degree of mechanization and automation, compound quality, low labor intensity, safe, drug-flying small loss, good sanitation conditions, etc. advantage, but the mixing chamber cooling difficulties mixer, mixing temperature is high and difficult to control, so that the temperature-sensitive rubber material is limited, not suitable for light-colored rubber material and variety and frequent changes in the plastic material kneaded. In addition mixer mixing device needs to be equipped with corresponding showings.


(1) The amount of plastic loaded


A reasonable amount of glue should be installed to ensure maximum by rubber friction and shear in the mixing chamber, the mating dispersed evenly. Depending on the size of the installed equipment glue features and characteristics of a given compound. Generally based on the total volume of the mixing chamber and fill factor calculated fill factor of 0. 55 to 0. 75. Such devices in a long time, due to the mixing of indoor wear, fill factor desirable large value, increase the amount of installed glue. As the ram pressure, or rubber greater plasticity, can also be a corresponding increase in the amount of installed glue.


(2) the pressure on the top bolt


Increase the pressure on the top bolt, not only can increase the installed capacity of plastic, and can make between rubber and rubber equipment and various parts of the interior more quickly and efficiently contact with each other and squeezed into the rubber compounding agents to accelerate the process, so shorten the mixing time and improve production efficiency, while reducing material in sliding contact surface of the device, increasing shear stress suffered gum, improving complexing agent dispersion, improve rubber quality. Therefore, it is more to take to increase the diameter of the top bolt hairdryer measures or increasing pressure to improve efficiency and mix mixer mixing quality.


(3) the shape of the rotor speed and rotor structure


The mixing process, the compound suffered shear rate proportional to the speed of the rotor. Improve rubber shear rate, can shorten the mixing time, the main measures to improve the efficiency of the mixer. Currently, the speed of the mixer has the original 20 r / min increased to 40 r / min, 60r / min, up to 80 r / min, so dark refining cycle from 12 ~ 15 min reduced to a minimum of l ~ l. 5 min. In recent years to adapt to the mixing process requirements, it has adopted a multi-speed or variable-speed mixer mixing, according to the plastic material properties and process requirements, speed change at any time, in order to obtain the best mixing effect. Structural shape mixer rotor has a significant impact on the mixing process. Oval rotor mixer of ribs from the original two to four, can play a more effective role of shear agitation. Can improve the production efficiency of 25 to 30%, and reduce energy consumption. In recent years, in addition to oval, there are triangular, cylindrical shape of rotor mixer, etc. are applied in production.


(4) kneading temperature


Mixer mixing process, the raw heat, cooling difficulties, so rubber heating up fast, high temperature. Usually by the refining temperature in 100 ~ 130 'C marsh around, there is also 170 ~ 1 90' C high temperature i Queensland refining, this process had to use in the synthesis of rubber mixing, slow mixing discharge temperature control when general In 125 ~ 135 'C, when rapid mixing discharge temperature of 160. C or more. I Kun Lian, the temperature is too high will reduce the mechanical shear for the role of rubber, so mixing uneven, and will exacerbate the thermal oxidation cracking rubber molecules, so that the physical and mechanical properties of rubber lower, while also prompting rubber and produce excessive carbon chemical bond between action and generate too much gel, so that decreased rubber plastic, plastic material surface roughness, resulting in rolling, extrusion processing difficulties.


 (5) dosing order


Plastic compounds, masterbatches should be the first to join, to form - whole, and then followed by the addition of other ingredients. Solid softeners and small medicine before adding fillers such as carbon black is added in order to ensure that they have adequate mixing time. Liquid softeners must be added, so as not to produce after the addition of carbon black dispersion difficulties caused clumping; after adding ultra accelerator and sulfur in the next machine to cool, or Sec kneading in the mixer was added, but its discharge temperature should be controlled at 100 'C or less.


(6) kneading time


Kneading time depends on the performance characteristics of the mixer, installed factors glue and rubber formulations and the like. Mixed: Gang, time to grow, can improve the dispersion with the agent, but likely to cause excessive mixing time is too long, will affect the curing properties of rubber compounds. Currently XM-2 5 0/20-type mixer mixing time is 10 ~ 12min.