In the molding and processing of plastic products, almost everyone has used black masterbatch. It is used for dyeing, anti-aging, and conductive products. Many problems in use often plague us.

1. What materials are the black masterbatch made of?

The materials that make up the black masterbatch are: A. Carbon black; B. Carbon black carrier; C. Carbon black wetting agent; D. Carbon black dispersant; E. Other processing aids.

2. Please introduce carbon black for black masterbatch.

According to international classification, there are more than 30 varieties in my country. Mainly divided into two categories: rubber and non-rubber. Among the carbon blacks for rubber, wear-resistant carbon blacks are mainly used, which can effectively improve the abrasion resistance of rubber tires. Among the carbon blacks for non-rubbers, there are only a few types of carbon blacks that can be used as black masterbatches. Channel carbon black is the most widely used in plastics, mainly due to its abundant source, high purity, and small particle size.

3. What is the carbon black carrier?

The carrier is the substance that carries carbon black. Generally, what raw materials are used in plastic products, and what raw materials are used in the carrier. The black masterbatch manufactured in this way has better compatibility with plastic raw materials. Such as: PS (polystyrene) plastic products, the black masterbatch carrier used is PS.

For polyethylene plastic products, the carrier is polyethylene. However, LDPE (High Pressure Polyethylene) is generally used because LDPE has strong carbon black carrying capacity and good processing performance. Other polyethylene HDPE and LLDPE can only produce low-concentration black masterbatch. For PP (polypropylene) plastic products, only black masterbatches with PP and LDPE as carriers can be used, but black masterbatches with HDPE, LLDPE and other plastics as carriers cannot be used. Of course, there is also a black masterbatch with recycled materials as a carrier.

4. Why does carbon black need a 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 looks fluffy and seems very light. For smooth processing, the carbon black must first be wetted. The choice of wetting agent is very critical. In order to reduce costs, there are not a few companies that use a large amount of products such as white oil or paraffin, which will seriously affect the strength of the processed products.

5. What dispersants are used in carbon black masterbatch?

There are two types of organic dispersant and inorganic dispersant. The high-grade black masterbatch uses organic dispersant, which is mainly used for plastic products with high environmental requirements. Low-grade black masterbatch uses inorganic dispersant, and calcium carbonate is commonly used. It can be judged from the packaging of the masterbatch that if there is only half a bag of 25 kg, inorganic dispersant must be used; the full bag is black masterbatch with organic dispersant. The use of inorganic dispersants can greatly reduce the cost of black masterbatch, but the fatal thing is that calcium carbonate has the effect of accelerating the aging of plastic products.

6. Does black masterbatch also need processing aids?

Of course it needs. A smooth process requires the correct selection of antioxidants, internal lubricants, external lubricants, modifiers and antistatic agents.

7. What are the processing methods for black masterbatch?

There are three types: single screw method, twin screw method and internal mixing method. Single-screw method: After mixing the materials with a mixer, they are pelletized by a single-screw extruder. Generally, the carbon black concentration is 18-20%. The process is backward and the environmental conditions of the production site are poor. Some start-up small factories still use this method for processing.

Twin-screw method: After mixing the materials with a mixer, the twin-screw extruder is used for stranding or water ring granulation. Due to the limited mixing capacity of the twin-screw machine, the masterbatch generally has a carbon black concentration of 25-32%. Internal mixing method: After mixing the materials with a mixer, adding them to the internal mixer for kneading, they are fed into the twin-screw extruder from the feeder, and pelletized by water ring or underwater. The masterbatch generally has a carbon black concentration of 40- 45%.

8. Does the processing method affect the performance of the masterbatch?

Yes. Obviously, the internal mixing method improves the carrier's carrying capacity for carbon black, and at the same time, the carbon black can enter the carrier more uniformly. Taking advantage of the mechanical kneading of the internal mixer, crushing the agglomerated particles, greatly reducing the agglomeration particle size of carbon black particles. The particle size and distribution of carbon black in the masterbatch are uniform, which cannot be replaced by the other two methods.

9. In what respects does the black masterbatch have outstanding performance?

In the dyeing of plastic products, the black masterbatch only needs 0.6%-0.8%, it will be extremely black, and it will not be blacker if you add more.

According to the test data, for products used outdoors in Xinjiang, if you need to rely on black masterbatch to prevent aging, you only need to use high-quality black masterbatch (not the kind that is used as a carrier, white oil wetting, calcium carbonate dispersion, etc.) , The content of carbon black in the product reaches 2-2.5%, that is: every 100 kilograms of raw materials, there are 5-6 parts (weight) of 40% carbon black masterbatch, which far exceeds any anti-aging product , The product life can reach more than 10 years. This is why drip irrigation products, water delivery products, and communication cable products are all black. In addition, carbon black has a special contribution to the increase of product strength and conductivity.

10. It seems that there are not so many black masterbatch used in actual production?

That's right. In actual production, about 2 parts of black masterbatch is generally used, and anti-aging additives are added to use the synergistic effect of anti-aging and carbon black to prevent aging, so as to reduce product costs. In addition, the length of outdoor use and product life requirements also determine the appropriate reduction in the amount of black masterbatch used. The premise is that the carbon black must form a continuous phase in the product, that is, there is a carbon black "film" to protect the plastic.

If too little black masterbatch is added, the carbon black phase (that is, the part with high concentration of small pieces) is discontinuous in the product. At the boundary between the phases, the plastic molecules are the most fragile and are directly hit by ultraviolet light, which accelerates the oxygen aging reaction. When carbon black is like an impurity in the product, it is better not to add it.