The main reasons for the generation of "self-sulfur" during the placement of mixed rubber materials are:

(1) the use of vulcanizing agent, accelerator too much;

(2) The loading capacity is large, the temperature of the rubber mixer is too high, and the film cooling is not enough;

(3) or premature sulfur, uneven dispersion of the drug resulting in local concentration of accelerant and sulfur;

(4) improper parking, that is, the temperature of the parking place is too high, the air is not circulating, etc.

How to reduce the rubber compound Mooney?

Rubber mixing glue Mooney is M (1+4), that is, in 100 degrees preheating 1 minutes, the torque size of the rotor for 4 minutes, that is, the size of the force blocking the rotation of the rotor. All can reduce the rotor rotation force can reduce Mooney, formula raw materials including raw glue: Natural rubber and synthetic rubber, choose natural rubber Mooney low or add plastic chemical solution to the natural rubber formula agent (physical plasticizer effect is not good) is a good choice, synthetic rubber is generally not add plastic agent solution, can usually add some low molecular weight lipid within the so-called dispersant or release agent, such as the hardness is relaxed, of course, also can increase the stearic acid or oil component; If in the process, the pressure of the top plug can be increased or the discharge temperature can be appropriately increased. If conditions permit, the temperature of cooling water can also be reduced.

Factors affecting mixing effect of mixer

Mixer mixing compared with the mixing machine mixing, mixing time is short, high efficiency, high mechanization degree of automation, rubber are of good quality, low labor intensity, operation safety, medicine, flying small losses, as well as good environmental health conditions, but the mixer mixing chamber heat dissipation difficulty, high mixing temperature and difficult to control, make the rubber is restricted, sensitive to temperature It is not suitable for mixing light colored rubber materials and frequently changing varieties of rubber materials. In addition, the mixer also needs to be equipped with the corresponding chip device.

(1) The amount of glue

A reasonable amount of glue should be able to ensure the maximum friction and shear in the mixing chamber, so that the compound dispersed evenly. The size of the glue loading depends on the characteristics of the equipment and the characteristics of the glue. It is generally calculated according to the total volume and filling coefficient of the mixing chamber, and the filling coefficient is 0.55 ~ 0.75. If the equipment has been used for a long time, the filling coefficient can be larger and the amount of glue can be increased because of the wear in the inner mixer. As the pressure of the top plug is larger, or the plastic material is more plastic, the amount of glue can also be increased accordingly.

(2) pressure of the top plug

To improve on the roof bolt stress, not only can increase the loading capacity, and can make the rubber and between equipment and rubber internal parts more quickly and effectively contact with each other and extrusion, accelerate the compound mixed with rubber process, so as to shorten the mixing time, improve the production efficiency, and can also reduce the material in the equipment of the sliding contact surface, increase the rubber, the shear stress Improve the dispersion of the compound and improve the quality of the compound. Therefore, at present, the measures of increasing the diameter of the top bolt air duct or increasing the wind pressure are mostly taken to improve the mixing efficiency and the quality of the mixing glue.

(3) Rotor speed and rotor structure shape

In the mixing process, the shear speed of the compound is proportional to the rotor speed. It is the main measure to improve the efficiency of the mixer to increase the shear speed of the compound and shorten the mixing time. At present, the speed of the mixer has been increased from the original 20 r/min to 40 r/min, 60r/min, up to 80 r/min, so that the smelting cycle has been reduced from 12 ~ 15 min to the shortest l ~ l.5 min. In recent years, in order to meet the requirements of mixing technology, we have adopted multi-speed or variable speed mixer mixing, according to the characteristics of rubber material and process requirements, the speed can be changed at any time, in order to get the best mixing effect. The structure shape of rotor of mixer has great influence on mixing process. The convex edges of the oval rotor of the mixer are increased from two to four, which can play a more effective role in shearing and stirring. It can increase production efficiency by 25 ~ 30 % and reduce energy consumption. In recent years, in addition to the oval, there are triangular, cylindrical and other rotor shape mixer in production has been applied.

(4) mixing temperature

In the mixing process of the mixer, the heat generation is large and the heat dissipation is difficult, so the rubber material warms up quickly and the temperature is high. Generally by the refining temperature in 100 ~ 130℃ bog, there are 170 ~ 1 90 ℃ high temperature I kun refining, this process has been used in the synthetic rubber mixing, the rubber discharging temperature of slow mixing is generally controlled at 125 ~ 135℃, the rubber discharging temperature of fast mixing is more than 160℃. Elder brother I refined, high temperature will reduce the effect on mechanical shear of the rubber, the mixed unevenly, and raise the thermal oxidation of rubber molecule cracking, reduce rubber physical and mechanical properties, at the same time, also would lead to produce too much chemical combination between rubber and carbon black and generate too much gel, make rubber plasticity drops, rubber surface rough, rolling, extrusion processing difficulties.

(5) Dosing sequence

Plastic rubber, mother rubber should be the first to join, so that the formation of the whole, and then add other coordination agent. Solid softeners and small agents are added before carbon black and other fillers are added to ensure adequate mixing time. Liquid softener must be added after adding carbon black to avoid agglomeration of carbon black and difficult dispersion; Super accelerator and sulfur are added after cooling in the lower chip machine, or added in the dense mixer during the second stage mixing, but the discharging temperature should be controlled below 100 ℃.

(6) Mixing time

The mixing time depends on the performance characteristics of the mixer, the amount of glue and the formula of the compound. Mixing: the increase of post and time can improve the dispersion of the compound, but too long time is easy to cause over-refining, and will also affect the vulcanization characteristics of the compound. At present, the mixing time of XM-250/20 mixer is 10 ~ 12min.