Why Black Silicone Rubber Products Can't Resist High Temperature
Carbon black is mainly composed of carbon, and contains a small amount of hydrogen, oxygen, nitrogen, sulfur, metal and other elements, these small amounts of hydrogen, oxygen, nitrogen, sulfur, metal and other elements.
Main chemical constituents of carbon black:
The content of carbon/carbon (C) elements (Wt%) is more than 93%.
The content of oxygen group (Wt%) is less than 7%.
Usually the chemical composition of carbon black products is these, but the chemical composition of different carbon black products will change, but the change is not very big.
What are the impurities in carbon black? 7_6 t: S* d: G / 4 G & X
Carbon black is not a pure substance. Carbon is the main component of carbon, and contains a small amount of hydrogen, oxygen, nitrogen, sulfur, metal and other elements. These impurity elements mainly exist in the form of hydroxyl, carbonyl, amino or cyanogen. B & H ~, R6 C5 y (}$Y, O6 f)
Carbon black is mainly produced by incomplete combustion or thermal decomposition of carbon-containing materials (coal, natural gas, heavy oil, fuel oil, etc.) under the condition of insufficient air. Incomplete combustion, oh, so it's not pure, nor is the pigment carbon black.


So what are the impurities in carbon black? Mainly as follows:
$N6 [3 V3 Q% P B + F
1. Moisture: Usually the moisture requirement of coal tar products is 4% of the national standard.
2. Mechanical impurities: The removal of impurities from raw oil makes it necessary for coal tar suppliers to have storage and processing capabilities. Of course, it also depends on the quality requirements when signing contracts with customers. In any case, impurities such as coke particles, refractory slag and rust will eventually affect the surface finish, gelling properties, tensile strength, flexibility, crack resistance and service life of rubber products. $Q}* z% J (V (e, p#) (B7 c)
8 X7 e33. Sulfur content: The existence of sulfur in silicone rubber early vulcanization, and even cause scorch, so that the change of plasticity-elasticity of silicone rubber ahead of time, resulting in the decline of tensile strength and elongation strength at the later stage of gelling.  Because coal tar is one of the by-products of medium coking, the sulfur content of coal tar depends on the supply of raw coal in the coking process. ) G * q "t (@'4). Metal impurities and salts: high content of metal impurities and salts will result in surface cracking, accelerated aging and shortened service life of rubber products. Among them, the content of metal elements is too high, which will reduce the reinforcement of carbon black, and then affect the wear resistance and hardness of rubber products. In the traditional coal tar quality index, the ash content of coal tar is generally required to be less than or equal to 0.13%.