Antistatic agent

Antistatic agents are chemical agents that increase the electrical conductivity and volume conductivity of the dielectric surface and prevent it from generating static electricity. The harm of static electricity spreads to various industrial and mining enterprises. It not only affects the quality of the product, but also generates sparks due to the excessive electric field strength of the static charge, igniting flammable vapor, gas or a mixture of dust and air, causing a major explosion accident. When the static electricity reaches a certain charge density, the interaction force occurs in different parts of the processed dielectric material, which affects the progress of the normal production process, which is the process interference caused by the electrostatic force. The weak current caused by static electricity, flowing through the human body for a long time, or instantaneous discharge to the human body will damage the health of the human body. [Types of Antistatic Agents] Antistatic agents can be classified into two types according to their properties: hygroscopic and surface active. The hygroscopic antistatic agent has hygroscopic or moisturizing properties and can form a water film on the surface of the dielectric; such materials include polysiloxanes, polyhydric alcohol amines, ethylene glycol, glycerin, sorbitol and inorganic salts ( Calcium chloride, lithium chloride, magnesium chloride). The surfactant-type antistatic agent has a lipophilic portion in the molecule firmly attached to the surface of the dielectric, and the hydrophilic portion absorbs moisture from the air to form a thin conductive layer on the surface of the resin to eliminate static electricity. According to the method of use, the antistatic agent can be classified into a external antistatic agent and an internal antistatic agent. In the mining, mineral processing and metallurgical industries, in order to prevent the electrostatic effects generated by the processing of mineral powders and metal powders, external antistatic agents are generally used; the surface coating antistatic agents used in the production of synthetic fibers are also externally used. The antistatic agent added during the manufacture of the synthetic resin film and the molded article is an internal antistatic agent. In the case of spraying (external) antistatic agent on the surface of the material, the antistatic effect of the conductive layer formed on the surface is removed by friction or washing, and the surface conductive layer formed by the internal antistatic agent may be lost. However, since a new antistatic agent molecule is moved from the inside to the surface in the near future, an antistatic effect can still be produced, so that the antistatic effect can be maintained for a long time. The external antistatic agent is a surfactant, a silicon compound or the like. In addition to the surfactant, there are other inorganic substances, such as filling metal powder, carbon black and the like in the solid dielectric, which can increase the volume conductivity and achieve antistatic effect. The surface active antistatic agent can be classified into a cationic type, an anionic type, a nonionic type or the like according to its ion form. Representative products of anionic antistatic agents are higher alcohol sulfate salts, aliphatic sulfonates, higher alcohol phosphate salts. Such an antistatic agent has a cationic moiety of a counter ion, and an alkylalkanolamine such as triethanolamine can be used in addition to a metal ion such as sodium or potassium. Anionic antistatic agents are characterized by good thermal stability. The cationic antistatic agent is represented by an alkyl quaternary ammonium salt and an alkylamine salt having 8 to 22 carbons, and a balanced ion of an anion portion may be used in addition to a halogen ion, nitric acid, sulfuric acid, perchloric acid or the like. This type of surfactant is one of the best in antistatic agents, but its thermal stability is slightly inferior to other types. The nonionic antistatic agent is a partially esterified product of a polyvinyl chloride derivative and a polyhydric alcohol, and has good thermal stability and can be used as an internal antistatic agent for food packaging films and the like. In addition, there are polymeric antistatic agents for spraying, which have the advantage of being durable and washable. [Mechanism of Antistatic Agent] There are four main ways in which antistatic agents can eliminate static electricity: (1) The hydrophilic group of the antistatic agent increases the hygroscopicity of the surface of the product to form a single molecule conductive film. (2) The ionic antistatic agent increases the ion concentration on the surface of the article, thereby increasing conductivity. (3) An antistatic agent having a large dielectric constant can increase the dielectric property between the friction body gaps. (4) Increase the smoothness of the surface of the product and reduce its friction coefficient. Among the above four modes of action, (1) and (2) can reduce the electrical resistance of the article, increase its conductivity, and accelerate the leakage of electric charge. (3) and (4) can reduce the generation of electric charge when rubbed. It is generally believed that the first two functions are the main functions of the antistatic agent. Of course, it is not necessarily all of the above functions for an antistatic agent. [Performance requirements of antistatic agent] The ideal antistatic agent should have the following conditions: (1) Antistatic effect is large and long lasting. (2) The heat resistance is good, and it does not decompose at the high temperature (120 to 300 ° C) of the molding process or when the hot working is repeated. (3) It has moderate compatibility with plastics, has certain compatibility, and has certain incompatibility. It can be well compatible with resin during mixing and melt processing, and it will not be obviously sprayed after molding. Precipitation, but the antistatic agent and the resin must also have certain incompatibility to ensure that when the surface of the antistatic agent molecular layer is damaged, the internal antistatic agent can ooze out in time to form a new molecular layer and restore the anti-static Electrical performance. (4) Does not affect the processing properties (such as melting point, viscosity, solubility, etc.) of the plastic and the properties of the product (such as transparency, colorability, printability, heat and mechanical properties, etc.). (5) Good compatibility with other additives, no antagonistic effect. (6) Non-toxic, odorless, no irritation to the skin. (7) The price is low.