Application of black masterbatch in plastic products

2020-05-12 739

In the plastic product molding process, black masterbatch has been used by almost everyone. It is used for dyeing, anti-aging, conductive products and so on. Many problems in the application often bother us. We will discuss some issues of common concern and hope to bring you harvest.

1. What information does the black masterbatch consist of?

The materials of black masterbatch are: A. carbon black; B. carbon black carrier; C. carbon black moisture wetting agent; D. carbon black Huan powder; e. other processing aids.

2. Please introduce carbon black for black masterbatch.

According to the world classification, there are more than 30 kinds in China. Mainly divided into rubber and non rubber two categories. In rubber carbon black, wear-resistant carbon black is the most important, which can effectively improve the wear resistance of rubber tires; in non rubber carbon black, only a few kinds of carbon black can be obtained as black masterbatch. Carbon black produced by tank method is widely used in plastic guess, mainly because of its rich origin, high purity and small particle size. In the meantime, it is 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). Because of the different types of carbon black, the quotation is very different. Because of its vivid nature, carbon black particles rarely exist as primary particles, and almost all exist as aggregate particles of certain size.

3. What about the carbon black carrier?

The carrier is the material carrying carbon black. Generally, the material used in plastic products is the material used in carriers. The black masterbatch produced in this way has good compatibility with plastic materials. For example: PS (polystyrene) plastic products, the use of black masterbatch carrier is PS. As for polyethylene plastic products, the carrier is polyethylene. However, LDPE (high-pressure polyethylene) is usually selected, because LDPE can bear carbon black best and has good processing function. While other polyethylene HDPE and LLDPE can only produce low concentration black masterbatch. As for the finished PP plastic products, only the black masterbatch with PP and LDPE as carriers can be used, but the black masterbatch with HDPE, LLDPE and other plastics as carriers cannot be used. Of course, there are also black masterbatch with recycled material as carrier.

4. Why does carbon black need wet agent?

The specific gravity of carbon black is about 2G / cm, because the particle size of carbon black is very small, the density is very small, it seems loose and light. To smooth processing, it is necessary to wet the carbon black first. The selection of wetting agent is very important. In order to reduce the cost, many companies use white oil or white wax and other products, which will seriously affect the intensity of processed products.

5. What are the dispersants used for carbon black masterbatch?

It can be divided into organic and inorganic laxatives. High grade black masterbatch uses organic dispersant, mainly for the use of plastic products with high environmental requirements, such as drip irrigation products. Low grade black masterbatch uses inorganic laxative, commonly calcium carbonate. It can be judged from the package of masterbatch. If only half a bag of 25kg is needed, inorganic laxative will be used; if the bag is full, black masterbatch with organic laxative will be used. The use of inorganic dispersants can greatly reduce the cost of black masterbatch, but it is fatal that calcium carbonate can accelerate the aging of plastic products.

6. Do black masterbatch need processing aids?

Of course. Smooth processing requires accurate selection of antioxidants, internal lubricants, external lubricants, modifiers and antistatic agents.

7. What are the processing methods of black masterbatch?

There are three methods: single screw method, double screw method and close love method. Single screw method: after the materials are mixed by the mixer, the single screw extruder is used to stretch and pelletize the materials. Generally, the carbon black concentration is 18-20%. The technology is backward, and the production site environment conditions are poor. It belongs to the screening technology, which is still used in some small start-up factories without cleaning up. Twin screw method: after the materials are mixed by the mixer, they are pulled by the twin-screw extruder or granulated by the water ring. Because the mixing ability of the twin-screw extruder is limited, the carbon black concentration of the masterbatch is usually 25-32%. Internal mixing method: after mixing the materials with the mixer, kneading with the mixer, feeding the materials into the twin-screw extruder by the feeder, and cutting the particles through the water ring or underwater, the carbon black concentration of the masterbatch is usually 40-45%.

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

Yes. Obviously, the internal mixing method improves the carrier's ability to carry carbon black, and carbon black can enter the carrier more evenly together. It shows the mechanical kneading advantage of internal mixer, which can break the gathering particles and greatly reduce the gathering particle size of carbon black particles. The other two methods can not replace the carbon black particle size and its distribution uniformity in the master particle.

9. In which aspects does black masterbatch have outstanding embodiment?

In terms of the dyeing of plastic products, the black masterbatch only needs 0.6% - 0.8%, which will be extremely black, no matter how much it is added, it will not be blacker. According to the test data, for the finished products used in the field in Xinjiang, if they need to rely on the black masterbatch for anti-aging, they only need to use excellent black masterbatch (instead of the kind with recycled materials as the carrier, white oil is wet, calcium carbonate is lax, etc.), and the content of carbon black in the finished products reaches 2-2.5%, that is to say, 5-6 masterbatches (weight) containing 40% carbon black per 100 kg of original guess have far exceeded the effect Any anti-aging goods, commodity life can reach more than 10 years. This is why drip irrigation goods, water delivery goods and communication cable goods are all black. In addition, carbon black has a special contribution to the strength and conductivity of finished products.


10. It seems that so many copies of black masterbatch are not used in practice?

That's right. In practice, we usually use about 2 parts of black masterbatch, add anti-aging additives, and use the synergistic effect of anti-aging and carbon black to reduce the cost of goods. In addition, the application time in the field and the service life of the products are required. It is also decided that the application amount of black masterbatch should be properly reduced, provided that carbon black in the products is necessary to form a continuous phase, that is, carbon black "film" maintenance plastic. If there are too few black masterbatch, the carbon black phase (i.e. some with high concentration of small pieces) is not connected in the finished product. At the boundary between the phase and the phase, the plastic molecule is the weakest, and it is directly impacted by ultraviolet light to accelerate the oxygen aging reaction. At the moment, carbon black seems to be impurity in the finished product, so it is better not to add it. When the boundary between phases is less than 280mm, it can avoid the impact of ultraviolet light, and the finished product is safe.

11. How to distinguish the quality of black masterbatch from its appearance?

Good quality black masterbatch with moderate luster and hardness. Too much oil, too much oil, too much gloss, too much calcium carbonate. The black masterbatch of good quality is bited with teeth, soft with crispness. Too soft indicates that there are too many organic laxatives, too soft and lax indicates that the carbon black concentration is low and contains more calcium carbonate, too brittle indicates that the carbon black content is too high, or the carrier is recycled.

12. What's wrong with the appearance of the finished product with pockmarked surface after using black masterbatch?

If the pockmarked surface is a protruding small point, it is clarified that only the loose masterbatch of the finished product processing equipment can be limited, and the carbon black aggregate particles can not be cut evenly, so the black masterbatch with lower concentration should be used; perhaps the masterbatch has too much calcium carbonate and too much white oil, which is extruded by single screw and twin-screw machines under high pressure, forming a small rigid block, unable to be loose. If the pockmarked surface is concave, it is formed by evaporation of small and medium molecular substances, so there is more oil.

13. Can the black masterbatch containing calcium carbonate be used?

To sum up. First of all, black mother guessed that if the fineness of calcium carbonate is 1000 mesh and the content is within 10%, the finished product without field exposure application request is a good choice with low price. The appearance of the product is glossy, the carbon black in the processing is even, the blackness is not affected, and the effect on the product strength is small. If the fineness of calcium carbonate is less than 1000 mesh, it may present dim luster, rough appearance and reduced strength of finished product. If the amount of calcium carbonate exceeds 10%, the appearance of the finished product will be dull and gray, the blackness will not be enough, and the strength of the finished product will be reduced. Secondly, in any field application of finished products with anti-aging requirements, calcium carbonate is not good. It depends on the service life of the product.

Article origin: Taishan conductive mica particles

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