First, the dispersion should be high
Black masterbatch is produced by carbon black. Raw carbon black is mixture that is dirty and very difficult to clean, it’s dusty, lightweight and fluffy. Unless large-scale treatment measures are used, it will foul machines and workers and make the working environment dirty. Because of this, casters generally choose to finish carbon black predispersion on a resin carrier, that is, black masterbatch. This resin carrier is clean, free flowing and easy to use. In addition, apart from being dirty, carbon black also has a characteristic that it is difficult to perform dispersion. If the raw carbon black is melted directly during injection molding, the coloring effect will be very poor. The carbon black stripes and spots that have no dispersion will clearly show up next to the less colored areas. Standard injection molding machines cannot disperse carbon black effectively.
Carbon black, which is difficult to disperse, also confuses color masterbatch producers. The high load black masterbatch produced by single or double screw extruders has very poor dispersibility. When the end user mixes or molds these black masterbatches, its performance is only slightly better than carbon black, but the effect is equally unsatisfactory. In order to achieve a stable high degree of dispersion, a high-level shearing mixer must be used to mix carbon black, such as a mixture of FCM or BANBURY. With sufficient strength, these mixers can completely mix the carbon black with the base resin. The type of carbon black used also affects the dispersibility. The smaller the carbon black particles, the harder the dispersion is.
The application of thin wax is in most demanding of dispersion requirements. The final product of poorly dispersed masterbatch can be easily seen by the naked eye from the corners. In addition to the lack of beauty, the poor dispersion of carbon black in the film significantly reduced the weathering resistance of the black film. Small particles with good dispersibility are the main features of the fiber industry. These fibers are used in ropes, yarns, carpets and other industries. Large machines simultaneously produce 30,000 strands of fiber at a speed of more than 5,000 meters per minute. If the dispersion of the masterbatch is too poor, it will break the fiber and cause production shutdown.
Second, strong coverage
The second factor that determines the quality of black masterbatch is coverage. This factor is especially important for masterbatches for scrap or recycled polymers. In these cases, the role of black is to cover the other colors in the scrap. Large-particle carbon black has poor coloring capabilities and does not easily cover all the other underlying colors. As a result, the final product is only deviated from the color. In the melting process, the ability to properly select the carbon black with high coloring ability to cover the existing color is the so-called covering power.
 Third, the liquidity is good
The third factor that determines the quality of black masterbatch is rheology and fluidity. If masterbatch itself has good dispersibility, but it cannot flow into the material to be molded, the effect of the production is not ideal. In general, the base resin used to produce the masterbatch has a higher rheology. In order to save costs, some masterbatch manufacturers use recycled materials, scrap as resin carriers. The flow properties of the masterbatches being produced thus will be significantly reduced, and if the rheology is not good, the labor will have troubles in the cycle time and appearance. It is worth noting that if the dispersibility and rheology are not high, some end-users will compensate by increasing the dilution ratio, but this will only increase the using  cost of masterbatch. Color masterbatch with the smallest dilution yields a uniform, well-dispersed black color.
 Fourth, compatibility is big
The compatibility is the fourth factor that determines the quality of the black masterbatch. If the masterbatch is produced by swarf or recycled material, it may contain contaminants or other non-meltable polymers. This can cause some unforeseen and difficult constraints, wasting final consumers' time and raw materials. At this time, the base resin can be selected to produce high-quality masterbatch, and the masterbatch has good compatibility in the melting process. High-quality masterbatches can be produced by using LLDPE, LDPE, HDPE, PP, PS, SAN, PA and other materials. If engineering grade and stringent physical properties have been noted, special polymer masterbatches can be obtained. Several international large-scale masterbatch manufacturers are conducting research to produce so-called "global universal" masterbatches. These masterbatches can be used in a wide range of other raw materials, have good rheology, and can be applied flexibly.
Fifth, the stability should be consistent
This is also the fifth factor that determines the quality of black masterbatch. One of the main manifestations of stability is the smooth carbon black ratio. If the percentage of carbon black is fluctuating, the amount of masterbatch that needs to be melted is not the same, and it is impossible to produce a product with the same hue. Some end-users have reported that the dilution ratios required by chemical manufacturers are usually 5-8% different, depending on how much material the masterbatch manufacturer has put into production. Obviously this is unacceptable. Of course, other factors such as the fluidity and dispersibility of the injected melt should be consistent with the amount of feed to each batch.
Sixth, the shade must be clear
The final factor that determines the quality of the black masterbatch is the shade of the color. There are various types of carbon black available on the market for the coloring of masterbatches, but the colors and prices of various types are also quite different. Large particle carbon black has a lower degree of coloration and different background color than small particle carbon black. Large-particle masterbatches are suitable for the production of bags such as garbage bags, but are not suitable for the production of aesthetically pleasing products such as TV signs or areas where UV protection is required, such as agricultural films or external pipes. For these products, only the higher-priced, small-particle carbon blacks are used. In addition, low transparency is also a characteristic of small particle carbon black.