Yuan Lei tells you the requirements of rubber products for fillers and the role of various carbon blacks in rubber.
Yuan Lei tells you the requirements of rubber products for fillers and the role of various carbon blacks in rubber.
(1) The surface of the reinforcing filler particles must have strong chemical activity, which can produce a good combination with rubber, and can improve the mechanical properties, aging resistance and adhesion properties of vulcanized rubber. The surface of non-reinforcing filler particles is chemically inert, and does not produce chemical combination with rubber, and does not affect the mechanical properties and weather resistance, acid and alkali resistance and water resistance of vulcanized rubber.
(2) It has high chemical purity, uniform fineness, and good wettability and dispersibility to rubber.
(3) It is not volatile, odorless, tasteless, non-toxic, and has good storage stability.
(4) Fillers for white, light-colored and colored rubber products also require no pollution and no discoloration.
(5) cheap and easy to get.
(1) Fineness: Generally speaking, the finer the reinforcing filler particles, the larger the specific surface area, the larger the contact area with the rubber, and the better the reinforcing effect. The finer the non-reinforcing filler particles, the better the mixing effect after adding rubber. However, it must be evenly dispersed, such as uneven dispersion, even if the particles are very fine, the mixing effect is not good.
(2) particle shape and crystal form: the shape of the filler particles is better to be spherical, and the sheet-shaped or needle-shaped filler is easy to produce directional arrangement when the vulcanizate is stretched, resulting in an increase in permanent deformation and a decrease in tear resistance. The carbon black and white carbon black in the reinforcing filler are amorphous, and other fillers are also crystalline. For example, although the chemical composition of silica powder and white carbon black is silica, the former is crystalline and the latter is amorphous. Crystalline packing is divided into two kinds of heteroaxial crystallization and equiaxial crystallization. Coaxial crystalline x, y, z triaxial similar, isotropic. Heteroaxial crystallization of x, y, z triaxial has significant difference, anisotropy in the commonly used non-metallic mineral filler, clay, graphite, diatomite belong to hetero-axial crystallization system. Calcium carbonate is an equiaxed crystal system. Rubber products with good wear resistance and tear resistance are required, and it is not suitable to use non-axial crystalline materials as reinforcing fillers.
(3) Surface properties: The powder filler is mixed with rubber, and its particles are surrounded by rubber molecules. The degree of wetting of the particle surface by rubber has a great influence on the reinforcement performance. Not easy to wet particles, in the rubber is not easy to disperse, easy to agglomerate, reduce its reinforcement. This condition can be improved by adding certain substances that help to increase wetting. For example, the reinforcing effect of calcium carbonate is very small. After adding fatty acids, the surface tension is reduced, the wetting degree is increased, and the reinforcing effect is improved.
Carbon black is the main reinforcing filler of rubber, and its composition is 90% ~ 99% of elemental carbon, and the rest is a small amount of volatile matter and water. In the production process of carbon black, its surface adsorption or combination of a small amount of carboxyl, quinone, phenol, lactone and other chemical groups. In the past, it has been considered that the reinforcing efficiency of carbon black depends only on its particle size (specific surface area) and structure, and has nothing to do with the chemical nature of its surface. In recent years, a large number of research results show that the chemical groups on the surface of carbon black particles can chemically react with rubber in the mixing process, so that the binder increases, and then improves the mechanical properties and aging resistance of vulcanizates.
Carbon black, or carbon black, is an amorphous carbon. Light, loose and very fine black powder, the surface area is very large, ranging from 10-3000m 2/g, is a carbonaceous material (coal, natural gas, heavy oil, fuel oil, etc.) under the condition of insufficient air by incomplete combustion or thermal decomposition of the product.
According to the performance of carbon black, there are "reinforcing carbon black", "conductive carbon black", "wear-resistant carbon black" and so on. Carbon black can be used as a black dye, used in the manufacture of Chinese ink, ink, paint, etc., but also often used in rubber production reinforcing agent; carbon black according to different uses, usually divided into pigment with carbon black, rubber with carbon black, conductive carbon black and special carbon black.
China is one of the earliest countries in the world to produce carbon black. In ancient times, people burned animal and vegetable oils and pine branches to collect black ash condensed from fire smoke, which was used to prepare ink and black pigments. This is called "soot" black ash is the earliest carbon black.
In 1912, it was found that carbon black has a reinforcing effect on rubber, and carbon black has gradually become an indispensable raw material for the rubber industry.
Carbon black generally refers to the carbon particles, generally due to the organic combustion is not sufficient, the hydrogen and oxygen elements into water, and carbon combustion is not sufficient, will be separated from the molecule, the formation of carbon black. With the furnace black production process can be obtained almost all the particle size range of carbon black, the same variety of carbon black, the particle size is not exactly the same, showing a particle size distribution range. Generally speaking, the particle size distribution is narrow for finer varieties. The finer the pigment black, the more contact points between the carbon black aggregates, and the stronger the cohesion between them. When the pigment black is added to the material, that is, when the initial carbon black is uniformly distributed, the work to be done for dispersion is greater, so as to separate the carbon black particles and finally reach the highest blackness and coloring.
There are two kinds of density of carbon black, one is the true density, which is determined by the elements and structure (or crystal structure) of carbon black. Without special instructions, the density of carbon black refers to the true density; the other is pour density or apparent density, which varies with the processing conditions of carbon black and needs to be measured frequently. The apparent density mainly provides the basis for the volume calculation of engineering equipment and containers such as packaging, storage and transportation.
Small particle size, high structure of carbon black pouring density is small. Carbon black with small particles, high structure, pure surface and large surface roughness has good conductivity. Rubber Technology Network learned that when preparing conductive rubber, the amount of carbon black should not be less than a certain critical value, otherwise too little carbon black in the rubber can not form a conductive channel or can not trigger field emission, so that the conductivity of the rubber can not meet the requirements.
1. Increase the wear resistance and service life of rubber products (reinforcing agent)
2. Cost savings, general rubber products are two parts of rubber and one part of carbon black (filler)
According to the use can be divided into two categories: rubber with carbon black, pigment carbon black
1. Classification of carbon black for pigment
According to the coloring ability of carbon black, it is usually divided into three categories, namely high pigment carbon black, medium pigment carbon black and low pigment carbon black. This classification system is often represented by three English letters. The first two letters indicate coloring ability, the last one indicates production method
For example: high pigment black: HCC(high color channel)
High pigment furnace black HCF(high color furnace)
The classification of color pigments is mainly based on particle size and blackness. High pigment channel black (10-14nm), medium pigment channel black (15-27 nm), medium pigment furnace black (17-27 nm), low pigment furnace black (28-70 nm)
2. Classification of carbon black for rubber
The nomenclature system takes into account the vulcanization speed and structure of the carbon black compound and consists of four systems. The first letter represents the vulcanization speed of the compound. N represents a normal vulcanization speed, and S represents a slow vulcanization speed. The first three letters of the following letter represent the carbon black nitrogen surface area range. The second and third numbers reflect different degrees of structure.
The nomenclature system takes into account the vulcanization speed and structure of the carbon black compound and consists of four systems. The first letter represents the vulcanization speed of the compound. N represents a normal vulcanization speed, and S represents a slow vulcanization speed. The first three letters of the following letter represent the carbon black nitrogen surface area range. The second and third numbers reflect different degrees of structure. (These are by national standards)
N220 is suitable for all kinds of rubber, wear resistance is 10%-20% higher than N330, can give the rubber particles high tensile strength and tear strength, and has a certain conductivity. It is mainly used for tread rubber of truck tire and passenger tire, and rubber products that need high strength and high wear resistance.
The wear resistance of N234 is about 10% higher than that of N220, and it can show good wear resistance when used under high severity. Mainly used for high-speed tire tread rubber and high-quality rubber products.
N326 has high tensile strength, tear strength, abrasion resistance and anti-cracking performance in natural rubber. It is mainly used for tread rubber of tires (including off-road tires) with high strength and low heat generation. It is also suitable for conveyor belts, sealing products and other high-quality rubber industrial products.
N330 is a kind of carbon black with good reinforcing performance, which can give the colloidal particles good tensile properties, tear resistance, abrasion resistance and elasticity. Mainly used for tire tread, cord rubber, sidewall and various rubber industrial products.
The reinforcing performance, wear resistance and crack resistance of N339 in tread compound are close to those of N220 carbon black, especially suitable for the combination system of styrene-butadiene rubber and butadiene rubber. Mainly used for passenger tires, truck tire tread rubber, conveyor belts, rubber hoses and various rubber industrial products with high wear resistance.
N375 and N339 performance is basically the same, heat generation is slightly lower than N339. Mainly used for car tires, truck tires and off-road tire tread rubber.
N550 is suitable for natural rubber and all kinds of synthetic rubber, easy to disperse, can give the rubber material high stiffness, extrusion speed, small mouth expansion, extrusion surface smooth. The high temperature performance and thermal conductivity of the vulcanizate are good, and the reinforcing performance, elasticity and recovery are also better. Mainly used in tire cord rubber, sidewall, inner tube and extrusion, calendering products rubber.
N539 rubber used in this product, the extrusion surface is smooth, small mouth expansion. The tensile strength and elongation of the vulcanizate are higher, the constant elongation stress is lower than that of N550, and the elasticity and fatigue resistance are better. It is mainly used for tire carcass compound, especially for natural rubber-based buffer layer compound, and can also be used for tire base compound, tape covering and other rubber products and wire and cable sheath materials.
N660 This product is suitable for all kinds of rubber. Compared with semi-reinforced carbon black, it has a higher structure, finer particles, and easy to disperse in rubber. The tensile strength, tear strength and constant elongation stress of vulcanized rubber are higher, while the deformation is small, the heat generation is low, and the elasticity and flexibility are good. Mainly used for tire wheel curtain tape, inner tube, bicycle, hose, tape, cable, footwear and calendering products, model products, etc.
N774 is suitable for all kinds of rubber. It is the carbon black with the largest particle size (product particle size is 80-170nm) and the lowest structure except thermal cracking carbon black. It is mostly used for buffer layer and ply rubber compound of tire carcass, rubber hose, extruded products, various industrial rubber products, wires and cables, etc. It can be filled in large quantities in rubber compound. Its vulcanized rubber has high elongation, low heat generation, high elasticity and good aging resistance. It can also be used instead of thermal cracking carbon black.
Thermal cracking method carbon black: rubber carbon black N990 series carbon black uses natural gas as raw material, no flame combustion under the condition of isolated air, cracking generation, called thermal cracking method carbon black, carbon black N990 its basic performance and furnace method carbon black have a big difference.
The advantages of carbon black N990 are mainly manifested in:
1. particle size and distribution, the average particle size is 280nm, the nitrogen surface area is 7-11 m2/g, the sulfur absorption value is 10 g/kg, and the CTAB method surface area is 9 m2/g;
The 2. particle aggregation degree is very small or the structure is very low, showing many individual spherical carbon black particles, and the base part is composed of a few fused particles. Compared with other varieties of carbon black, the overall aggregation degree is very low.
Pyrolytic carbon black is the largest particle size of all carbon black varieties (N990:200-500nm,N880:100-200nm). Earlier, pyrolytic carbon black was used as a filler for auto parts. At that time, the use of pyrolytic carbon black was relatively narrow and the price was relatively cheap. Later, it was found that thermal cracking carbon black has high filling amount, good elasticity of rubber compound and superior permanent non-deformation performance, which is widely used in rubber products such as automobiles and machine tools. The price also increases with the increase of demand and the increase of natural gas price. Due to rising prices, downstream manufacturers are mostly replacing natural gas semi-reinforced and sprayed carbon black, and the demand for pyrolytic carbon black has declined, but in individual industries, pyrolytic carbon black is still in use for its good performance.
Carbon is an element, a predominantly tetravalent non-metallic element, found in nature (e. g. as diamond and graphite) and a constituent of coal, petroleum, asphalt, limestone and other carbonates, and all organic compounds.
A black pigment consisting of a charred substance (such as charcoal or bone charcoal).
Both are currently in vogue.There are no specific authoritative standards and definitions. If you do online promotion, these two words should pay attention to publicity. No one can say that carbon black N220, carbon black N330, carbon black N550 and carbon black N660 are more standardized than carbon black N220, carbon black N330, carbon black N550 and carbon black N660.
Rubber, carbon black, properties, used, vulcanization, particle, filler, pigment, main
The difference between barium sulfate（BaSO4） and barium sulfite（BaSO3）
Kaolin is a non-metallic mineral, which is a kind of clay and clay rock mainly composed of kaolinite clay minerals. Because it is white and delicate, also known as white earth. It is named after Gaoling Village, Jingdezhen, Jiangxi Province.