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.