As a new type of plastic products, PVC conveyor belts are widely used in coal mines and various factories and enterprises due to their light weight, long life, good flame retardancy, and resistance to friction. However, because PVC is a good insulator with high surface resistance and poor electrical conductivity, it is easy to cause explosions or fires and other major accidents due to the accumulation of static electricity in coal mines, which are rich in gas and easy to generate static electricity. Therefore, it is necessary to improve the antistatic performance of PVC flame-retardant conveyor belts through formulation design.
How does static electricity happen?
When a conveyor belt made of plastic and rubber materials is running in a coal mine, the positive and negative charges on the belt body will lose balance due to friction and generate static charges. The static charge accumulated on the surface of the conveyor belt is not easy to disappear. When it reaches a certain value, it Will produce discharge sparks to grounded objects, causing fire or gas explosion.
Antistatic method
The method of plastic antistatic is mainly to control the generation and accumulation of static electricity. Controlling the generation of static electricity is mainly to reduce the generation of static electricity by reducing or preventing friction; controlling the accumulation of static electricity is mainly through grounding conduction, increasing the relative humidity of the environment, and adding antistatic agents or conductive materials (such as conductive carbon black, metal powder, etc.) Accelerate the leakage of static electricity and avoid the accumulation of static electricity.
Antistatic formula
For PVC flame retardant conveyor belts used in coal mines, the antistatic properties of the formulation are very important. In order to make the static charge generated during the operation of the conveyor belt timely conduct and leak through itself, we must consider various factors such as process and production cost, and choose appropriate antistatic agents and conductive materials to reduce the flame retardant PVC conveyor belt Surface resistance, to ensure that the surface resistance of the conveyor belt is not more than 3×10 8Ω.
Antistatic agent
In order to make PVC flame-retardant conveyor belts have good antistatic properties, the traditional method used in China is to add quaternary ammonium salt cationic antistatic agents to the formulation; the practice has proved that quaternary ammonium salt cationic antistatic agents have strong adhesion, Excellent antistatic performance, but it has many shortcomings in actual use.
First of all, the quaternary ammonium salt antistatic agent itself has a poor heat resistance and is easily decomposed by heat, which can reduce the thermal stability of the PVC resin and accelerate the aging process of the PVC resin.
Secondly, the quaternary ammonium salt cationic antistatic agent can chemically react with the lead stearate, barium stearate and other metal soap heat stabilizers in the PVC flame retardant conveyor belt formulation to form a stable compound, thus affecting the antistatic effect of the belt, reduces the thermal stability of the resin.
Therefore, quaternary ammonium salt cationic antistatic agents should not be used in the production process of PVC flame-retardant conveyor belts with extremely high heat resistance requirements, and non-ionic antistatic agents with good thermal stability and antistatic properties should be used. .
Conductive materials
Because carbon black is a natural semiconductor material, its conductive properties are durable and stable, and the resistivity of polymer materials can be greatly adjusted. In addition, it has a wide range of sources and is cheap. Therefore, carbon black is used as a conductive filler.
Conclusion
In the production process of PVC flame-retardant conveyor belt, adding non-ionic antistatic agent and conductive material acetylene carbon black can greatly improve the anti-static and flame-retardant performance of PVC conveyor belt while reducing production costs. And make it have good physical and mechanical properties.