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　　Carbon black characteristics and application of relations

1, blackness and particle size

Blackness directly associated with the particle size of carbon black, the smaller the particle size distribution, specific surface area is larger, the higher the blackness of the carbon black. This is because even though the primary particles fuse into a native has aggregate, than table can still play a role, but its native fine particles, the greater the specific surface area of condensed matter. Color more black, presented by the uv effect is better. Due to the fine particles of carbon black absorbance is higher than the coarse particle of carbon black, so the tinting strength is stronger. But when the particle size reduced, because the blue light is absorbed by priority, for this color become brown.

Small primary particles gives larger specific surface area, carbon black dispersion and increase the difficulty of general wettability can be adjusted by surface treatment and improve the dispersion.

　　Carbon black particle specific surface area and performance relationship

　　2, the structure

Carbon black particles not only in the form of primary particles, and in the production of fused into condensed matter. This kind of condensed matter is made up of primary particles by chemical bonds. In the process of coagulation, composed of a large number of chain branch primary condensed matter called high structure carbon black carbon black. And native agglomerations composed of primary particles less chain branches carbon black, it is called a structure of low carbon black. See below:

	High structure	Low structure

　　Of aggregate structure of carbon black is black, the more general chain branches closer to its structure, the higher, the lower structure conversely, the influence of carbon black structure on performance, see the table below:

The influence of carbon black structure on performance

　　3, surface chemical

Different carbon black production methods of the surface chemical properties. Carbon black surface with different oxygen functional groups such as carboxyl, aliphatic and phenolic groups, carbonyl, etc.) within. Generally high oxygen containing functional groups of carbon black, high volatile flux, its color is adjustable performance is good, the fluidity is higher also. Carbon black sample heated to 825 + 25 oc expressed as a percentage weight loss after the volatilization of carbon black. Black carbon oxygen gene, the more volatile portion.

4, hygroscopicity and density

Carbon black is a kind of large surface area of material, thus has certain moisture absorption. Moisture absorption amount of silica is mainly determined by surface area size. Can strengthen measures, especially in the packaging, storage and transportation process to take measures to reduce the hygroscopicity of the product. Because of high moisture content (moisture absorption quantity) may cause problems for processing, so is a special packing requirements for some varieties of carbon black.

Powder or granular pigment carbon black black pigment used in a given plastic mixing depend on the type of dispersion and the characteristics of the resin, but processing capacity is also very important factors, most of today's dispersing equipment can play a shear force, enough to granular dispersed evenly.

Carbon black in the application of plastic industry in the choice before, must determine its purposes, such as used for coloring, prevent ultraviolet light, or conductive and so on.

　　1, tinted with carbon black

Usually better to the plastic coloring black pigment, black pigment could be selected according to color features or physical and chemical properties, of black coloring with the choice of varieties are basically with the blackness of the finished product must be achieved. Complete blackness with very fine black pigment can be particularly high requirements of coloring; PE bags, plastic bags, cable materials, such as product of medium level blackness, can use low specific surface area, high structure carbon black varieties; Plastic color, black there was a tiny error of weighing and ingredients, all can lead to clear off color, therefore, appropriate USES particle size is larger, tinting strength poor low carbon black pigment, dosage of carbon black can be slightly larger, so weighing error is relatively small, and has the advantages of dispersivity is good, price is low.

For gray plastic, adopt fine grained often appear brown, gray, black pigment and the thick black pigment particles can produce blue gray.

Compared with other organic pigment, carbon black in addition to the scattered difficult, other performance are good. Amount of carbon black with science, can provide good antistatic or conductive.　

Carbon black is essentially non-toxic, but more easily to float in the sky and pollution, reason often in the form of masterbatch for plastics industry, in eliminating pollution at the same time improve the carbon black dispersion in the plastic.

Carbon black for plastic pigments, commonly used dosage forms of powder and granular. Less granular carbon black dust dispersed more difficult, so using powdered carbon black in the plastics colouring.

2, the application of uv protective

Carbon black in the plastic industry is one of purposes of anti ultraviolet aging, because carbon black have higher optical absorption, and can effectively prevent the plastic from the sun and light oxidation degradation. Black as the role of ultraviolet light stabilizers in the plastic are: to convert light energy into heat energy. To protect the plastic surface from a certain wavelength of radiation exposure; Intercept groups and anti aging effect, preventing catalytic degradation. Ultraviolet particularly harmful to polyolefin, tests showed that when the concentration of the carbon black of a certain fineness in the sophomore can achieve perfect ultraviolet shielding effect.

Carbon black for plastic uv aging protection, depends on the size, structure and surface chemical carbon black.

Carbon black particle size is small, because surface area increases, the ability to absorb light or shading increased, so the enhanced uv protection, but the particle size of less than 20 nm, its protective effect to the same level, the reason is that when the particle size through the hours, the backward scattering is reduced, and the light of the continued will endanger the stability of the polymer.

Lower structure, namely, aggregate size is small, with aggregate geometric smaller size, will enhance the protection of polymer, which is the cause of the structure of low carbon black is black.

Carbon black surface oxygen groups, namely the volatilization of high, can eliminate polymer decomposed gene, so protection is also enhanced.

　　Carbon black dispersing equipment: