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Esd Antistatic Products

Feb 08, 2019

Method used in antistatic products

In order to prevent the harm of static electricity in daily production, from the perspective of electrostatic engineering or safety engineering, it should start from controlling the occurrence and accumulation of electric charge and rapidly eliminating or leaking the generated electric charge.

For the electronic products, the ion wind nozzle can be selected; for the flammable electrified body such as oil products and organic solvents, explosion-proof electric consumers, radiation type electric consumers, safety self-inductive electric consumers, etc. can be selected; dust, particles and the like are distributed in the space. The charged body can be selected from the air-type consumer; the surface charged body formed by film forming, processing, paper processing, printing plastic or rubber sheet forming, processing, fabric forming, processing, and the like. A safe self-inductive consumer can be selected.

The most active and effective antistatic method is to quickly leak the generated static electricity to the earth, and there are three methods for leaking static electricity:

1) Grounding

Connecting live objects to the ground, even when other anti-static measures are used, grounding is essential. Compared with the general electrical grounding method, since the amount of static electricity is small, when it is converted into a current, it is generally only a few tens of microamperes, so it is only necessary to use a simple grounding. That is, the grounding wire with a cross-section of 1.25 mm and a total resistance of less than 1000 ohms can achieve the purpose of leaking static electricity. In the case where the charged body is a vibrating body or the grounding wire is susceptible to mechanical damage, the grounding wire must have sufficient strength. In some cases, if the grounding device is improperly installed or removed for a selected time, or if the grounding site is improperly selected, electrostatic discharge may occur due to the disaster. For example, when a flammable liquid is poured into a metal container, if a grounding wire is placed during the filling process, a spark discharge may occur and cause a fire. Therefore, the grounding device should be connected before filling. If a conductive tire or a conductive positioning wheel is used to mount the bottom of the container, the container can be automatically grounded when it is placed in a predetermined position. For a filament body with a low conductivity and almost no leakage of static electricity, even if a grounding device is installed, it is difficult to leak accumulated static electricity. In this case, an antistatic additive or a conductive material is added to increase the insulator. Conductivity, plus grounding device.

Grounding is a very important measure for ESD protection.

2) Improve the humidity of the surrounding environment

The sheet resistance of organic synthetic polymers is related to the relative humidity and temperature of the surrounding environment. The higher the humidity, the lower the surface resistance drops. Generally, it can be humidified by discharging steam, sprinkling water, or using a humidifier or an ultrasonic evaporator. These methods can be empty

The relative humidity of the gas is increased to more than 70%. However, when using the humidification method for electronic products, consideration should be given to the increase in failure caused by the drop in insulation. If an antistatic pen is added to the insulating material, the method of increasing the ambient humidity is more effective.

3) Increase the conductivity of the material

This measure is the most fundamental and important method of antistatic. The main methods for increasing the conductivity of materials are:

a. External antistatic agent method. For example, methods such as external spraying, dipping, and application of an antistatic agent are used. Simple spray-type antistatic agents and eluents for recordings, clothing, etc. fall into this category.

b. External durable antistatic agent method. For example, in the post-processing of plastics, rubber, fibers, etc., an antistatic agent is added to cause the surface of the material to be attracted to each other by anion or a cation, or to be crosslinked by heat treatment, or to fix the antistatic agent with an adhesive, etc. The material is resistant to washing and dry cleaning and antistatic.

c. Internal antistatic agent method. For example, in rubber, fiber, paper, plastics, and coatings, an antistatic agent is added to a solid or liquid by blending. This method of adding an antistatic agent has a durable antistatic effect. However, the antistatic agent to be added is required to have form stability, workability, compatibility with materials, and does not adversely affect metal corrosion and friction properties, and also considers whether or not there is toxicity.

d. Mixed with conductive materials. The polymer material is mixed with a conductive material to make it a conductive material that always has antistatic properties. Examples of the conductive material include a metal (for example, stainless steel wire), graphite, a metal coating material, a conductive metal compound covering material, a covering or composite material containing a conductive carbon black polymer, and the like. In the insulator, usually mixed into o. 05% to 2% conductive material, can achieve long-lasting antistatic effect.

e. Other methods. For example, electroplating, coating, surface modification, and the like. The surface modification method can form a hydrophilic high polymer skin layer on the surface of the material, or carry out graft polymerization on the surface of the material with a hydrophilic monomer, and can also use physical methods such as irradiation, heat treatment and discharge treatment. To improve the static conductivity of the surface.

Anti-static products adopt more methods described in the above paragraph c, that is, high-density polymer materials with anti-static penalty, mixed with carbon black to increase the conductivity and promote the leakage of static electricity.