As we all know, plastic boasts good electrical isolation property. Therefore, it is widely used in every field of industry and our daily life. But the high resistivity on the plastic surface usually makes it easy to generate the accumulation of static electricity, which will cause bad phenomena such as dust collection, electric shock or spark discharge, all of which are not conducive to the processing and the use of plastic products.
Ⅰ. The use of antistatic agent
There are many antistatic treatment methods for plastics, such as mechanical methods, humidity adjustment, and physical and chemical modification. As the first two methods will be restricted by equipment and environment, a chemical modification that adds antistatic agent is widely used at present. That is, add an antistatic agent into resin or apply it on the surface of the plastic to reduce the resistance on the surface of plastic products and alleviate or dissipate the accumulation of static electricity in the process of plastic processing and usage.
There are many ways to classify antistatic agents, and we always classify them according to chemical structure and usage. According to chemical structure, antistatic agents can be divided into cationic type, anionic type, zwitterionic type, and nonionic type.
According to the usage, there are two kinds of antistatic agents, namely, the coating method and the compounding method. The coating method has the advantages of quick effect, material saving, and low requirements on the heat resistance of antistatic agents. But the antistatic effect can not last, and after washing and friction, the coating of the antistatic agent will disappear. The compounding method has the advantages of washing resistance, friction resistance, long-lasting antistatic effect, and simple usage.
Ⅱ. The ideal antistatic agent should have the following conditions:
1. Antistatic effect is large and long lasting;
2. It has good heat resistance and will not decompose under high temperature (120~300℃) of processing or repeated thermal processing;
3. Moderate compatibility with plastics, etc. It can be well compatible with resins during mixing and melt processing. There will be no obvious blooming and precipitation after molding. However, antistatic agents and resins need to have certain incompatibility to ensure that when the molecular layer of the antistatic agent on the surface is damaged, the internal antistatic agent can be precipitated in time to form a new molecular layer and restore the antistatic effect;
4. It will not affect the processing properties (such as melting point, viscosity, solubility) and product properties (such as transparency, coloring, printability, heat sealability and mechanical properties) of the product;
5. Good compatibility with other additives, no antagonistic effect;
6. It should be odorless, tasteless, non-irritating to the skin.