Category: Antistatic rubber

1) When mixing black antistatic rubber compound, the structure of carbon black is easily damaged after mechanical shearing, and the plasticity is increased. As a result, the antistatic property (ie, electrical conductivity) is impaired, so that the kneading can reach a uniform dispersion degree. Be careful to prevent refining. The plasticity of the rubber compound should be controlled at 0.4~0.45.

2) The hot-smelting time of the film-out type should not be too long, and the pitch should not be too small. The reason is the same as above.

3) The deeper the vulcanization cross-linking, the smoother the electrostatic path and the better the electrostatic discharge effect.

The antistatic properties of rubber have a lot to do with rubber, but it is equally important to use suitable antistatic additives. It can even be said that its significance is even worse. At present, antistatic agents for commonly used rubbers fall into two categories: conductive carbon blacks and ionic surfactants. They are suitable for black and light colored products, respectively.

1) Among the carbon black carbon blacks, the conductive varieties are acetylene black, conductive furnace black, conductive black, etc.; and the most used and most widely used acetylene black, because its price is relatively low. Moreover, since it contains a large amount of volatile matter, the electrical conductivity is somewhat poor, and this can satisfy the need for antistatic. In addition, conductive carbon black can also provide some reinforcing effects, including increased tensile stress and hardness. When used as an antistatic agent, the amount of acetylene black is generally from 20 to 30 parts. However, it is not suitable for light-colored antistatic products, nor for products with high hygienic requirements (such as medical antistatic products).

2) Ionic surfactants Their antistatic properties are derived from surface polarity and are also related to their ability to diffuse and to be compatible. If such surfactants have good compatibility with rubber, their diffusion and migration will be constrained, and the conductivity will be pinned. Conversely, if the compatibility is too poor, it will spread out and migrate too quickly. Sex is also difficult to last. Therefore, the principle chosen should be to match the compatibility of the rubber. Theoretically, the hydrophilic group in the surfactant-type antistatic agent molecule has a good antistatic effect because it can form a uniform molecular layer on the surface. The antistatic agent SAS variable has been formulated into natural rubber, and the amount of such antistatic agent is preferably 7 to 10 parts.

3) Vulcanization system should note that in the antistatic formula of black products (with carbon black as antistatic agent), it is not advisable to use effective or semi-effective vulcanization systems such as low sulfur high or no sulfur, because the crosslinked structure of these systems is single. The main disulfide bond is not conducive to the formation of long-chain structure of carbon black, thus affecting the establishment of conductive channels. Conventional high sulfur and low vulcanization systems should be used as much as possible to improve electrical conductivity. Typical vulcanization system ratios are: sulfur 2.5, zinc oxide 5, stearic acid 2, accelerator 1.5. In the case of using a light-colored antistatic agent, since the surfactant has a plasticizing effect, the distance between the rubber molecules is increased, and the performance is affected, and the level of sulfur (3-3.5 parts) can be appropriately increased.

4） The filling system uses a large amount of silicate filler to adsorb the surfactant, which will offset its antistatic effect. In addition, it also affects the foaming of the sponge, so it is best to use calcium carbonate as a filler.

5） Plasticizers, such as the production of antistatic sponge products, can use more plasticizers to facilitate foaming.

More and more applications have raised the antistatic requirements, especially with the expansion of rubber in electronic computer applications, the probability of static electricity is also increasing, and people’s awareness of static electricity is also increasing. In many countries, antistatic measures are increasingly standardized. The most important of these is the development of various antistatic devices, one of which is antistatic rubber. Antistatic rubber products must not only act to remove static electricity, but also prevent electric shock accidents caused by leakage of low voltage lines. Depending on the application, antistatic rubber can be classified into the following categories.

1） Antistatic rubber is required in some places where it is prone to danger, such as roads and tires that tend to accumulate static electricity. Compared with metal or concrete paving materials, they are more secure and hygienic in the workplace, and they also have good antistatic effects.

2 ）The possibility of fire and explosion during the transportation of flammable and explosive liquids exists. In this case, rubber hoses with good electrical insulation properties are prone to fire. If the oil hose is antistatic, it can ensure the safety of oil transportation.

3） Anti-static conveyor belts used in explosive and flammable places can eliminate accidents caused by sparks, especially in places where tape is used to transport chemical fiber, which can effectively prevent fire accidents caused by fibers being adsorbed on the surface of the belt.

4) Anti-static rubber shoes are also anti-static bulk products. The volume resistance of these special shoes on the ground is 10 10^3〜8Ω∙CM. When the shoes are grounded, the current through the human body should be <5mA. anti-static rubber shoes used in hospital operating rooms. To remove static electricity generated by the floor, moving stretchers, and tool cart wheels.

5) Some factories have high-purity production sites and need to establish a long-term antistatic environment. Antistatic equipment must be used.

Rubber is an electrically insulating material, and when its surface is rubbed, the charge in a static state accumulates to form static electricity. When static electricity accumulates to a certain amount, it is released in the form of a spark. If the amount of discharge is slight, it will not pose a hazard to the human body, but when the discharge reaches a certain level, it will cause an electric shock. In order to protect personal safety, the rubber used in this case must be an antistatic rubber that can remove static electricity. The dangers caused by static electricity are roughly the following:

1 When static electricity is released, if there is fire, flammable or explosive materials around, it will cause fire;

2 Injury to the human body, although this kind of electric shock is not fatal, it is always harmful to the human body;

3 The surface with static electricity will absorb the surrounding dust. For example, when the skin of a textile mill draws a yarn, static electricity is generated between the yarn and the yarn due to friction. When the static electricity accumulates to a certain extent, it will adsorb the flying yarn in the surrounding air and affect the operation.

In short, the exact definition of antistatic is not to prevent the generation of static electricity, but to remove the static electricity that has accumulated.

(1) Resistivity of rubber

The electrical insulation capability of rubber is conventionally characterized by resistivity (unit: Ω ∙ CM), where the range of 10^4〜7Ω ∙ CM is used as the semiconductor rubber, which is greater than this as the insulating rubber, and less than this is the conductive rubber. All kinds of rubber have good electrical insulation properties. In contrast, neoprene and nitrile rubber have the lowest resistivity and are called “semiconductor rubber”. They are often used as the first choice for antistatic, but they are not the only consideration. The object can be adjusted by adding an antistatic agent.