The classification of carbon black in China can be generally divided into two categories according to past customs: classification by manufacturing method and classification by use and usage characteristics.
1. According to the manufacturing method, carbon black can be divided into three categories: Contact process carbon black, furnace method carbon black and pyrolysis method carbon black.
(1) Contact process carbon black
The Contact process is to make the flame of the feed gas combustion contact with the collection surface at a lower temperature, so that the carbon black generated by pyrolysis is cooled and attached to the collection surface, and then collected to generate carbon black. This method includes slot method carbon black, drum method carbon black, and disc method carbon black. The first two types of carbon black are both produced on a large scale in China, while the latter is not common.
Tank method carbon black: Tank method is a method of using natural gas as raw material, using a specially designed fire nozzle to burn in contact with air in the fire chamber. The flame then contacts the slowly reciprocating channel steel, causing carbon black to deposit on the channel steel and collect it to generate carbon black. Because its raw material mainly uses natural gas with methane as the main component, it is also known as natural gas tank black or gas tank black.
The carbon black produced by using solid raw materials such as naphtha, anthracene, or anthracene oil, supplemented by coke oven gas or natural gas with low methane content, is called trough mixed gas carbon black, also known as mixed gas carbon black or crude anthracene carbon black. In the production of slot mixed carbon black, the carbon black produced by removing the cooling surface of the channel steel is called slot free mixed carbon black. This type of carbon black, as long as reasonable control is carried out in the production process, there is no significant difference in the quality of mixed gas carbon black with the same tank method. Bath process carbon black is one of the older and important carbon black varieties, and is a typical representative of Contact process carbon black.
Drum method carbon black: Drum method carbon black is a method of producing carbon black by using a rotating steel drum to cool the collection surface and make it come into contact with the raw material flame for collection. This method is usually used in areas without natural gas resources. Most use tar gas, water gas, or city gas as gas raw materials; Solid or liquid raw materials are mostly made of anthracene, anti-corrosion oil, etc. The production capacity of the equipment is higher than that of the tank method carbon black.
(2) Furnace process carbon black
The furnace method is used to produce carbon black by using gaseous hydrocarbons, liquid hydrocarbons, or a mixture of gaseous and liquid hydrocarbons in a certain proportion as raw materials, supplied with an appropriate amount of air, and burned and cracked in a specially designed reaction furnace at a certain high temperature. The produced carbon black is suspended in the flue gas and then cooled and collected. Carbon black produced using only gaseous hydrocarbon raw materials, such as natural gas and oilfield gas, is called gas furnace method carbon black; Carbon black produced by using only liquid hydrocarbon raw materials, such as oil from coal tar system or petroleum system, is called oil furnace carbon black; The carbon black produced by the simultaneous use of gaseous and liquid hydrocarbon raw materials is called oil gas furnace method carbon black. Lamp smoke carbon black, which has a long history in China, is a type of carbon black produced by adding liquid raw materials dropwise to a disc and burning it in a large flame under restricted air conditions. Due to the ancient method of producing carbon black using wick, it is still used today, hence the name lampblack. It has now been replaced by a new variety of carbon black. Lamp smoke carbon black can actually be classified as furnace process carbon black. Furnace method carbon black, especially oil furnace method, has been a rapidly developing method for carbon black production in the past fifty years.
(3) Pyrolytic carbon black
Pyrolysis of carbon black is a method of generating carbon black through intermittent (combustion heat storage and thermal decomposition stages) or continuous (single pyrolysis method) thermal cracking using natural gas (CH4) or acetylene gas (CH2) as raw materials in a preheated reactor, isolating air. The carbon black produced by cracking natural gas as the main raw material is called thermal cracking carbon black. The carbon black particles generated by thermal cracking are different in size and can be further divided into two types: fine particle thermal cracking carbon black (100-200 ù) and medium particle thermal cracking carbon black (200-500 ù). The carbon black generated by the thermal cracking of acetylene gas as a raw material is called acetylene carbon black. The use of arc method and explosion method to produce acetylene black also belongs to pyrolysis method. Acetylene black has a well-developed chain branch structure and good conductivity, making it suitable for making conductive products.
2. Classification by purpose and usage characteristics
Carbon black can also be divided into three categories based on its purpose and usage characteristics: rubber carbon black, pigment carbon black, and conductive carbon black.
(1) Carbon black used in rubber products, when combined with a certain amount of carbon black, can cause reinforcement and filling effects to improve the performance of rubber products. The carbon black used is called rubber carbon black. There are many kinds of carbon black for rubber, including furnace carbon black, Contact process carbon black and pyrolysis carbon black.
According to the usage characteristics of carbon black in rubber, such as operational performance, wear resistance and reinforcement of products, it can be further divided into fast pressing carbon black, high elongation carbon black, semi reinforced carbon black, universal furnace black, etc. These are just customary forms of address, without any taxonomic significance. In the past decade, on the basis of normal structure oil furnace method carbon black, various new varieties of high structure and low structure oil furnace method carbon black with different particle sizes have been produced, such as high structure medium ultra wear-resistant furnace black and low structure ultra wear-resistant furnace black. This method of structural classification has practical significance. In addition, in the rubber industry, in order to demonstrate the reinforcing effect of carbon black on rubber, it is sometimes customary to classify carbon black into two categories: hard carbon black and soft carbon black. The former has a good reinforcing effect on rubber; The latter has poor reinforcement effect and largely plays a filling role. Most of the Contact process carbon black and oil furnace method carbon black belong to hard carbon black; A small portion of oil furnace method carbon black, gas furnace black, and thermal cracking carbon black belong to soft carbon black.
There are ten types of carbon black used in rubber in China's standard (HG4-48-74). It is classified and named based on production methods, raw materials used, and performance.
In recent years, the United States has adopted a new naming method for carbon black used in rubber. It is named based on the principle of linking the vulcanization rate of carbon black rubber, the particle size and structure of carbon black, etc. Usually, a naming convention of one prefix and three digits is used. The prefix represents the curing rate (N represents the normal curing rate, S represents the slow curing rate); The first digit in the back represents the range of particle size (represented by the particle size measured by an electron microscope), and the particle size range of carbon black for rubber can be divided into ten grades from 0 to 9 as listed in Table 1-1; The second and third numbers can be selected arbitrarily.
(2) Pigment carbon black
Pigment carbon black is mainly used as a black pigment in industries such as ink and paint. The requirements for pigment carbon black vary among different industries, so the variety of pigment carbon black is also increasing. Pigmented carbon black can be divided into three types based on its coloring intensity (blackness) and particle size: high colored carbon black, medium colored carbon black, and ordinary colored carbon black (see HG4-564-74). In the ink industry, carbon black is customarily divided into long flow, medium flow, and short flow carbon black based on its viscosity and fluidity in the base material. Various chemical post-treatment methods, such as ozone post-treatment, can increase the fluidity of carbon black in ink.
(3) Conductive carbon black
Utilizing the low or high resistance properties of certain carbon black to be used in different products, such as conductive rubber, radio components, etc., is called conductive carbon black. Acetylene black is an important type of conductive carbon black, commonly used in the battery industry. In addition, there are also furnace method conductive carbon black and trough method conductive carbon black.
