Review of the previous issue (review the past and learn the new can be a teacher)

1. Why should rubber be molded?

2. What factors affect rubber plasticization in internal mixer?

3. Why do all kinds of rubbers have different plasticizing properties?

4. Why is the plasticity of raw rubber used as the main quality standard of plastic rubber?

5. What is the purpose of mixing?

6. Why does the mixture agglomerate?

7. Why does too much carbon black in the compound produce "dilution effect"?

8. How does the structure of carbon black affect the properties of the compound?

9. Why does carbon black affect the scorch property of rubber compound?

10. What is one-stage mixing and what is two-stage mixing?

11. Why should the film be cooled before storage?

12. Why should the sulfur adding temperature be controlled below 100 ℃?

Technical dry goods delivery in this period:

1. Why should the mixed film be stored for a certain period of time before it can be used?

There are four purposes for the storage of mixed rubber film after cooling: (1) to recover the fatigue of rubber compound and relax the mechanical stress during mixing; (2) to reduce the shrinkage of rubber compound

(3) make the mixture continue to diffuse in the process of parking, promote the uniform dispersion; (4) make the rubber and carbon black further form rubber, improve the reinforcement effect.

2. What is the order of dosing in mixing?

Dosing sequence and pressure time are important factors affecting mixing quality. The mixing efficiency and uniformity can be improved by adding chemicals in different stages

There are special rules in the order, such as: liquid softener and carbon black should not be added at the same time to avoid agglomeration. Therefore, it is necessary to strictly implement subsection dosing.

If the pressure time is too short, the rubber and the medicine can not be fully rubbed and kneaded, resulting in uneven mixing; if the pressure time is too long, resulting in too high temperature in the mixing chamber, affecting the quality,

Reduce efficiency. Therefore, the pressurization time must be strictly enforced.

3. What is the effect of filling capacity on the quality of mixing and mixing?

The filling capacity refers to the actual mixing capacity of the internal mixer, which often only accounts for 50-60% of the total capacity of the mixing chamber of the internal mixer. If the capacity is too large, there will be no sufficient space for mixing, so it is not suitable for mixing

It can be fully stirred, resulting in uneven mixing; high temperature, easy to cause self sulfur rubber; but also cause motor overload. The capacity is too small and there is not enough friction between the rotors

Resistance, idling, also cause uneven mixing, so that the quality of rubber mixture is affected, but also reduce the utilization of equipment.

4. Why should liquid softener be added at last in rubber mixing?

If liquid softener is added in the mixing process of rubber compound, the raw rubber will expand excessively, which will affect the mechanical friction between rubber molecules and fillers and reduce the viscosity

At the same time, it will cause uneven dispersion and even agglomeration. Therefore, liquid softener is usually added at the end of mixing.

5. Why does the rubber mixture "self sulfur" after a long time of storage?

The main reasons for "self sulfur" during the storage of rubber compound are: (1) too many vulcanizing agents and accelerators are used; (2) large filling capacity and over temperature of rubber mixer

If the temperature is too high, the film cooling is not enough; (3) if the sulfur is added too early, the medicine material is not evenly dispersed, resulting in local concentration of accelerator and sulfur; (4) improper parking, that is, the temperature of the parking place is too high

High temperature, no air circulation, etc.

6. Why should there be a certain air pressure for mixing rubber in internal mixer?

During mixing, in addition to raw rubber and chemicals, there are quite a number of voids in the mixing chamber of internal mixer. If the pressure is insufficient, raw rubber and chemicals will not be enough

After increasing the pressure, the rubber compound will be subjected to strong friction and kneading up and down, so that the raw rubber and the compounding agent can be mixed evenly quickly

Even. Theoretically, the greater the pressure, the better. However, due to the limitation of equipment and other aspects, it is impossible for the pressure to be unlimited. Generally speaking, the wind pressure is the highest

6kg / cm2.