Introduction to the concept of masterbatch carbon black and related problems
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Introduction to the concept of masterbatch carbon black and related problems

In plastic products processing, black masterbatch is used by almost everyone. It is used for dyeing, anti-aging, conductive products and so on. But in the process of use, there are often a variety of problems that perplex us. Today’s small carbon black manufacturers will discuss some issues of common concern, hoping to bring you harvest.
1: Composition of black masterbatch
The materials of black masterbatch are: A. carbon black; B. carbon black carrier; C. carbon black wetting agent; D. carbon black dispersant; e. other processing aids.
2: Types of black masterbatch carbon black
According to the international classification, there are more than 30 varieties in China. It is mainly divided into rubber and non rubber. The main carbon black for rubber is wear-resistant carbon black, which can effectively improve the wear resistance of rubber tire; in non rubber carbon black, there are only several kinds of carbon black that can be used as black masterbatch.
The trough carbon black is widely used in plastics because of its rich sources, high purity and small particle size. Among them, it can be divided into high pigment carbon black (particle size 9-17mm), medium pigment carbon black (particle size 18-25mm) and low pigment carbon black (particle size 26-37mm).
Due to the different varieties of carbon black, the price varies greatly. Carbon black particles, because of their multi activity, rarely exist as primary particles, almost all exist in a certain range of particle size agglomerated particles.
3: What is carbon black carrier?
The carrier is the material carrying carbon black. General plastic products use what raw materials, carrier uses what raw materials. The black masterbatch made in this way has good compatibility with plastic raw materials. For example: PS (polystyrene) plastic products, its use of black masterbatch carrier is PS. For polyethylene plastic products, the carrier is polyethylene.
However, LDPE (high pressure polyethylene) is generally used because LDPE has the strongest carbon black bearing capacity and good processability. Other polyethylene HDPE and LLDPE can only produce low concentration black masterbatch. For PP (polypropylene) plastic products, only the black masterbatch with PP and LDPE as the carrier can be used, but the black masterbatch with HDPE, LLDPE and other plastics as the carrier cannot be used. Of course, there are also black masterbatches with recycled materials as carriers.
4: Why carbon black needs wetting agent
The specific gravity of carbon black is about 2G / cm. Due to the small particle size of carbon black, the apparent density is very small, and it seems to be very light. In order to process smoothly, carbon black must be wetted first. The choice of wetting agent is very important. In order to reduce costs, a large number of enterprises use white oil or paraffin wax and other products, which will seriously affect the strength of processed products.
5: What dispersants will be used in carbon black masterbatch?
It can be divided into organic dispersant and inorganic dispersant. High grade black masterbatch uses organic dispersant, which is mainly used for plastic products with high environmental requirements, such as drip irrigation products. Low grade black masterbatch uses inorganic dispersant, and calcium carbonate is commonly used.
Judging from the masterbatch packaging, only half a bag of 25kg must use inorganic dispersant; the full bag is black masterbatch with organic dispersant. The use of inorganic dispersant can greatly reduce the cost of black masterbatch, but calcium carbonate can accelerate the aging of plastic products.
6: Does black masterbatch need processing aids?
Of course. The right antioxidant, internal lubricant, external lubricant, modifier and antistatic agent should be selected for smooth processing.
7: What are the processing methods of black masterbatch?
There are three processing methods: single screw method, twin-screw method and close contact method.
Single screw process: the materials are mixed by the mixer and granulated by single screw extruder. Generally, the carbon black concentration is 18-20%. The process is backward and the environmental conditions on the production site are poor. It is an obsolete process. It is not ruled out that some small factories still use this method for processing.
Twin screw method: the material is mixed by a mixer, and then pelletized by a double-screw extruder. Due to the limited mixing capacity of the twin-screw extruder, the carbon black concentration of masterbatch is generally 25-32%.
Internal mixing method: the materials are mixed by the mixer and kneaded in the internal mixer, and then fed into the twin-screw extruder by the feeder, and the particles are cut through the water ring or under water. The carbon black concentration of the masterbatch is generally 40-45%.
8: Do processing methods affect the properties of masterbatch?
That’s for sure. Among them, the internal mixing method can improve the bearing capacity of carbon black, and carbon black can enter the carrier more evenly. The other two methods can’t be replaced by the other two methods to make full use of the advantages of internal mixer in crushing agglomerated particles, greatly reducing the agglomeration particle size of carbon black particles, and even distribution of carbon black particles in masterbatch.
9: In which aspects should black masterbatch have outstanding performance?
In the dyeing of plastic products, the black masterbatch only needs 0.6% – 0.8%, and it will be extremely black, and it will not be blacker any more. According to the test data, if the products used outdoors in Xinjiang need to rely on black masterbatch for anti-aging, only high-quality black masterbatch should be used (instead of black masterbatch with recycled material as carrier, white oil wetting, calcium carbonate dispersion, etc.).
The content of carbon black in products reaches 2-2.5%, that is, there are 5-6 masterbatches (weight) containing 40% carbon black per 100 kg of raw materials, which plays a far more important role than any anti-aging products, and the product life can reach more than 10 years.
That’s why drip irrigation products, water delivery products, communication cable products are all black. In addition, carbon black has a special contribution to the strength and conductivity of products.
10: It seems that there are not so many parts of black masterbatch in actual production?
you ‘re right. Generally, about 2 parts of black masterbatch are used in actual production, and anti-aging additives are added. The synergistic effect of anti-aging and carbon black is used to reduce the product cost. In addition, the use of black masterbatch should be reduced according to the requirements of product life and the length of outdoor use. The premise is that carbon black must form a continuous phase in the product, that is, there is a carbon black “film” to protect plastic.
If too little black masterbatch is added, the carbon black phase (i.e. the part with high concentration of small pieces) is discontinuous in the product. At the boundary between phases, plastic molecules are the most vulnerable, which is directly hit by ultraviolet light and accelerates the oxygen aging reaction. At this time, carbon black is like impurities in the products, so it is better not to add carbon black. When the boundary between phases is less than 280mm, the product can avoid the impact of ultraviolet light, and the product is safe.

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