22. Why should the dosing sequence be specified?
The purpose of the dosing sequence is to improve the efficiency of refining, to ensure the quality of mixed rubber. Generally speaking, the dosing order is: (1) add plasticizing rubber softening, so that it is easy to mix with the matching agent. (2) add small drugs: zinc oxide, stearic acid, accelerator, antioxidant, etc., these are important components of the rubber, the first to join to facilitate their uniform dispersion in the rubber. (3) Carbon black or other fillers such as clay, calcium carbonate and so on. (4) Liquid softener, rubber material expansion so that carbon black and rubber is easy to mix. If not in accordance with this dosing order (except for special requirements of the formula), it will seriously affect the quality of rubber mixing.

23. Why the same formula has several kinds of raw rubber and use
With the development of rubber industry raw materials, synthetic rubber varieties are increasing, in order to improve the rubber and improve the physical and mechanical properties of vulcanized rubber, improve the processing performance of rubber, reduce the cost of rubber products, is often in the same formulation of several kinds of raw rubber and used.

24. Why does the rubber produce too high or too low plasticity?
The main reason for this situation is that the plasticizing rubber plasticity is not appropriate; mixing time is too long or too short; mixing temperature is not appropriate; and with the rubber is not mixed well; plasticizer added more or less; less carbon black added more or more varieties with the wrong will be produced. Improvement is appropriate to grasp the plasticity of the plasticizer, control the mixing time and temperature, and with the rubber needs to be mixed evenly, with the agent should be weighed accurately and strengthen the inspection.

25. Why is the specific gravity of the rubber mixing material is too large or too small?
Caused by the matching agent weighing inaccuracy, omission and misallocation. Carbon black, zinc oxide, calcium carbonate more than the prescribed amount of raw rubber, oil plasticizers, etc. less than the prescribed amount, there will be a specific gravity of the rubber over the prescribed situation. On the contrary, the result is also opposite. In addition to the rubber mixing, too much powder flying or sticking to the container wall (such as a small pill box), add material failed to pour clean, can cause the specific gravity of the rubber material is too large or too small, to improve the method is to check with the weighing of no error, strengthen the operation, to prevent powder flying and pay attention to the uniformity of the rubber mixing.

26. Why the hardness of the mixing compound will produce too high, too low
Caused by the hardness of the rubber material is mainly due to inaccurate weighing of agents, such as vulcanizing agent, reinforcing agent, accelerator weighing higher than the formula dosage, resulting in vulcanized rubber hardness is too high; on the contrary, such as rubber, plasticizer weighing more than the formula dosage or reinforcing agent, vulcanizing agent, accelerator weighing less than the formula dosage is bound to cause vulcanized rubber material hardness is on the low side. Improvement measures and overcome plasticity fluctuations in the same factors. In addition, the addition of sulfur, such as uneven pounding, will also cause fluctuations in hardness (localized too large or too small).

27. Why does the rubber have a slow vulcanization start?
The main reason for the slow start of vulcanization of rubber is that the weighing of accelerator is less than the specified amount, or the mixing omits to add zinc oxide or stearic acid; secondly, the carbon black variety is wrong, which sometimes also causes delay in the vulcanization speed of rubber. Improvement measures are to strengthen the three inspections, weighing materials accurately and so on.

28. Why does the rubber produce undersulfurization?
The under-sulfurization of rubber is mainly caused by the omission or under-matching of accelerator, vulcanizing agent and zinc oxide, etc. However, improper mixing operation and excessive flying of powder can also lead to under-sulfurization of rubber. Improvement measures are: in addition to weighing accurately, strengthen the three inspections, do not miss or misallocation of materials, but also should strengthen the mixing process operation, and to prevent a large number of powder fluttering and dispersion.