ESD research on antistatic materials
The level of static charge accumulated by a material is related to the speed of static dissipation. Generally, the lower the resistance value of a material, the faster its static dissipation speed is, and it is not easy to accumulate static electricity. On the contrary, the higher the resistance value of a material, the slower its static dissipation speed is, and it is easy to accumulate high static electricity. Under normal circumstances, the surface or volume resistivity of static materials can be below 1011Ω/square or 1010Ω˙m. If it is in an explosive environment, the surface or volume resistivity of antistatic materials must be below 108Ω/square or 106Ω˙m. There are three ways to make a material have antistatic ability:
1. The material itself has antistatic ability, such as cotton, wood, paper and soil, but the antistatic ability of these materials will be affected by temperature and relative humidity, and become insulating materials.
2. Coating antistatic materials such as carbon powder, antistatic agent, etc. on the surface of insulating materials can form a conductive layer on the surface of insulating materials. Most commercial antistatic agents are applied to the surface of materials. Through the hydrophilic group on the outside, they absorb moisture in the air and increase the conductivity of the surface of the material. Therefore, the relative humidity in the environment will affect the effect of the conductive layer on the surface of the material. Generally, when the relative humidity is below 40% ~ 50% [5], its effect will be reduced.
3. Adding carbon powder, antistatic liquid or metal fiber to the insulating material manufacturing process makes the material into an antistatic material or a conductive material. In the manufacturing process of rubber, plastic or liquid, adding carbon powder or metal powder can improve its conductivity and make it a conductive material. Its effect is not affected by relative humidity, but it will change the durability of the material itself. In the chemical process, static electricity often accumulates on insulating products or equipment. If antistatic products or equipment can be used and grounded, the static electricity can be easily dissipated to the ground.