The use of antistatic agents can be divided into external coating method and internal blending method Two kinds. The external coating method has the advantages of simple operation, low material consumption, low heat resistance requirements for antistatic agents, and does not affect the molding and processing properties of the product. However, the antistatic effect is not long-lasting. After washing or rubbing, the antistatic agent coating The layer peels off easily, so it is a temporary antistatic treatment. The internal blending method has the advantages of washing resistance, friction resistance, heat resistance, long-lasting antistatic effect, and simple use.
How to use antistatic agents
1) Cleaning In order to obtain a uniform and dense antistatic agent coating, the plastic surface must be cleaned to completely remove surface dust, grease, etc. before applying the antistatic agent. It can be cleaned with a neutral detergent solution of about 1%. After cleaning, it needs to be placed in a dust-free room to dry.
2) Mix the antistatic agent with water, ethanol or ethyl acetate and other solvents to a concentration of 0.2%~2% Solution, the concentration of the solution should be as thin as possible while ensuring the antistatic effect, because a solution with a high concentration will be sticky and easily absorb dust.
3) Coating The coating method is selected according to the shape of the product. Commonly used coating methods include direct method, dipping method and spraying method. The direct method is to use tools such as cotton cloth, flannel, brushes and rollers to apply the antistatic agent liquid on the product. It is simple, effective and the most widely used. The dipping method is to immerse the product in an antistatic agent liquid. It is suitable for small products with complex shapes or large quantities. The spraying method uses a spray gun to spray the antistatic agent liquid on the product. It has the advantages of fast speed, high efficiency, and uniform coating.
4) Drying The coated product should be fully dried to harden the coating layer at a temperature of 30 ~ 40C and a relative humidity of Under the conditions of 60% ~80%, it takes about 3 hours to dry. After drying, it must be placed under natural environmental conditions for 5 hours.
Internal blending method operation requirements
The blending method is to mechanically mix antistatic agents and resins and then process them to form antistatic products. Commonly used antistatic agents are cationic and zwitterionic.
Antistatic agents are hygroscopic compounds that contain a certain amount of moisture. During the molding process, the presence of a small amount of moisture will cause a decrease in product quality, so the antistatic agent should be fully dried before being added to the resin. Can be dried under hot air at 70 ~ 80C for 4 hours.
The amount of antistatic agent added should be based on the performance of the antistatic agent itself, the type of resin, processing conditions, product form and resistance 0%。 Depends on the degree of electrostatic effect requirements, the general amount is 0.3% ~3. 0%. Thin products require less addition than thick products.
The mechanism of action of antistatic agents
Different types of antistatic agents not only have different chemical compositions and usage methods, but also have different mechanisms of action.
(1) Mechanism of action of externally applied antistatic agent
This type of antistatic agent generally uses water, alcohol or other organic solvents as solvents or dispersants. When a polymer material is impregnated with an antistatic agent, the lipophilic groups in the antistatic agent molecules will be adsorbed on the surface of the material. After impregnation and drying, the hydrophilic groups in the antistatic agent molecules on the surface of the polymer material after the moisture is removed are arranged toward the air side, which can easily absorb environmental moisture, or combine with moisture in the air through hydrogen bonds to form a The single-molecule conductive layer allows the generated static charge to leak quickly to achieve antistatic purposes.
(2) Mechanism of action of surfactant internal blend antistatic agent
And during the molding process of polymer materials, if it contains a sufficient concentration of antistatic agent, when the mixture is in a molten state, the antistatic The agent molecules form the densest alignment at the interface between resin and air or resin and metal (machinery or mold), in which the lipophilic group extends to the inside of the resin and the hydrophilic group extends to the outside of the resin. After the resin is cured, the hydrophilic groups on the antistatic agent molecules are aligned toward the air side, forming a single-molecule conductive layer.
During processing and use, stretching, friction, and washing will cause defects in the antistatic agent molecular layer on the surface of the material. Antistatic propertiesEnergy also decreased accordingly. However, unlike externally applied antistatic agents, after a period of time, the antistatic agent molecules inside the material will continue to migrate to the surface, allowing the defective parts to recover and show the antistatic effect again.
Since the above two types of antistatic agents achieve antistatic purposes by absorbing environmental moisture and reducing the surface resistivity of the material, they are Dependence on ambient humidity is large. Obviously, the higher the ambient humidity, the stronger the water absorption of the antistatic agent molecules and the more significant the antistatic performance.
(3) Action mechanism of polymer permanent antistatic agent
Polymer permanent antistatic agent is a new type of antistatic agent that has been researched and developed in recent years and is a hydrophilic polymer.
When it is blended with the polymer matrix, on the one hand, due to the strong mobility of its molecular chain, it is easy for protons to move between molecules Move, conduct and release the generated electrostatic charge through ionic conduction;
On the other hand, antistatic ability is achieved through its special Reflected in dispersed form. That is, the polymer permanent antistatic agent is mainly distributed in fine layers or tendons on the surface of the product to form a conductive surface layer, and is distributed almost in a spherical shape in the center, forming a so-called “core-shell structure”. Path leaks static charge.
Because the polymer permanent antistatic agent achieves the antistatic effect by reducing the volume resistivity of the material, it does not completely rely on surface water absorption. , so it is less affected by the humidity of the environment.
