In the molding and processing of plastic products, black masterbatch is almost universally used, used for dyeing, anti-aging, conductive products, etc. Many problems that arise during use often trouble us. The editor will now discuss some issues that everyone is concerned about together, hoping to bring you a harvest.

What information is the black masterbatch composed of?

The materials that make up black masterbatch include: A. carbon black; B. Carbon black carrier; C. Carbon black tide wetting agent; D. Carbon black dispersing agent; E. Other processing aids.

2. Please introduce carbon black for black masterbatch.

According to world classification, there are over thirty types in China. It is mainly divided into two categories: rubber and non rubber. The primary carbon black used in rubber is wear-resistant carbon black, which can enhance the wear resistance of rubber tires; There are only a few types of carbon black that can truly serve as black masterbatch in non rubber carbon black. The slot method carbon black is widely used in plastic guessing, mainly due to its rich history, high purity, and small particle size. During this period, it is further 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 types of carbon black, there is a significant difference in pricing. Carbon black particles, due to their high vividness, rarely exist as native particles, and are simply aggregated particles of a certain size.

3. What's wrong with carbon black carriers?

The carrier is the substance that carries carbon black. Usually, plastic products use the same material as the carrier. The black masterbatch produced in this way has good compatibility with plastic materials. For example, the black masterbatch carrier used in PS (polystyrene) plastic products is PS. Regarding polyethylene plastic products, the carrier is polyethylene. However, LDPE (High Pressure Polyethylene) is usually chosen because LDPE has strong carbon black bearing capacity and good processing function. However, other polyethylene HDPE and LLDPE can only produce low concentration black masterbatch. Regarding 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, black masterbatches can also be used as carriers with recycled materials.

Why does carbon black require a wetting agent?

The specific gravity of carbon black is about 2g/cm, because the particle size of carbon black is very small, it reflects a low density and appears loose, appearing very light. To achieve smooth processing, it is necessary to first wet the carbon black. The selection of wetting agents is crucial. To reduce costs, many companies use products such as white oil or white wax, which will seriously affect the strength of the processed products.

What are the dispersants used in carbon black masterbatch?

There are two types of dispersants: organic dispersants and inorganic dispersants. Black masterbatch uses organic dispersants and is primarily used in plastic products with high environmental requirements, such as drip irrigation products. Low grade black masterbatch uses inorganic dispersants, commonly including calcium carbonate. Judging from the packaging of the mother batch, if only half a bag of 25 kilograms is needed, it is definitely using inorganic dispersants; The bag is filled with black masterbatch using organic dispersants. The use of inorganic dispersants can greatly reduce the cost of black masterbatch, but what is fatal is that calcium carbonate has the effect of accelerating the aging of plastic products.

6. Do black masterbatches also require processing aids?

Of course it is necessary. A smooth processing process requires accurate selection of antioxidants, internal lubricants, external lubricants, modifiers, and anti-static agents.

What are the processing methods for black masterbatch?

There are three methods: single screw method, double screw method, and close fitting method. Single screw method: After mixing the materials with a mixer, the single screw extruder is used to pull and granulate them. Usually, the carbon black concentration is between 18-20%, and the technology is outdated. The production site environmental conditions are poor, which is a screened technology. Some small factories that have just started still use this method for processing. Twin screw method: After using a mixer to mix the materials, the twin-screw extruder is used to pull or water ring granulate them. Due to the limited mixing ability of the twin-screw machine itself, the concentration of carbon black in the master batch is usually between 25-32%. Internal mixing method: After mixing the materials with a mixer, they are kneaded in the mixer, and then fed into a twin-screw extruder by a feeder. After being cut into pellets through a water ring or underwater, the masterbatch usually has a carbon black concentration of 40-45%.

Does the processing method affect the functionality of the mother batch?

Yes. Obviously, the mixing method has improved the carrier's ability to carry carbon black, and together, carbon black can enter the carrier more evenly. The mechanical kneading advantage of the internal mixer is demonstrated by crushing aggregated particles, greatly reducing the particle size of carbon black particles. The size and even distribution of carbon black particles in the master batch cannot be replaced by the other two methods.

9. In what aspects do black masterbatches stand out?

In terms of plastic finished product dyeing, black masterbatch only needs 0.6% -0.8%, which will be extremely black, and no matter how much it is added, it will not become even darker. According to experimental data, for finished products used in the field of Xinjiang region, if it is required to rely on black masterbatch for anti-aging, only excellent black masterbatch needs to be used (instead of using recycled materials as carriers, such as wet white oil, loose calcium carbonate, etc.), and the content of carbon black in the finished product reaches 2-2.5%. That is to say, for every 100 kilograms of raw materials, 5-6 parts (by weight) of masterbatch containing 40% carbon black have a far greater effect than any anti-aging product, The lifespan of the product can reach more than 10 years. That's why drip irrigation products, water delivery products, and communication cable products are all black. In addition, carbon black has special contributions to increasing the strength and conductivity of finished products.

10. It seems that such a large number of black masterbatches have not been used in practical production?

That's right. In practical production, about 2 parts of black masterbatch are usually used, and anti-aging additives are added. The synergistic effect of anti-aging and carbon black is used to prevent aging and reduce the cost of the product. In addition, the length of time it is used in the wild and the lifespan of the product can be requested, which also determines the appropriate reduction of the amount of black masterbatch used, provided that carbon black is necessary to form a continuous phase in the product, that is, there is a carbon black "film" to maintain the plastic. If there are too few black masterbatches involved, the carbon black phase (i.e. some with high concentration of small flakes) will not be connected in the finished product. At the boundary between phases, plastic molecules are weak and are directly impacted by ultraviolet light, accelerating the oxygen aging reaction. At this moment, carbon black appears as an 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 good.

How to judge the quality of black masterbatch from its appearance?

A high-quality black masterbatch with a glossy and moderate softness and hardness. Excessive oil and excessive brightness indicate that too much oil has been added, and a dull luster indicates that the carrier is either recycled material or excessive calcium carbonate. High quality black masterbatch bitten with teeth, soft with a crispy texture. Too soft indicates too much organic dispersant, soft and lax indicates low carbon black concentration with more calcium carbonate, too brittle indicates high carbon black content, or the carrier is recycled material.

12. What is the reason for the small pitted surface on the surface of the finished product after using black masterbatch?

If the pockmarked surface is a protruding small tip, it is necessary to clarify that the loose processing equipment of the finished product can only limit the ability of the masterbatch. The masterbatch cannot cut the carbon black particles evenly, and a lower concentration of black masterbatch should be used; Perhaps the mother batch contains too much calcium carbonate and too much white oil, which are extruded by single screw and twin screw machines under high pressure, forming small rigid blocks that cannot be dispersed. If the pockmarked surface is concave, it is formed by the evaporation of small molecular substances in the mother's guess, which means there is too much oil.

Can black masterbatch containing calcium carbonate be used?

Let's summarize it. Firstly, if the black female guesses that the fineness of calcium carbonate is 1000 mesh and the content is within 10%, it is a good choice for finished products without outdoor exposure requirements, and the quotation is low. The appearance of the product has good luster, and the carbon black is loose and uniform during processing. The blackness is not affected, and the impact on the strength of the product is relatively small. If the fineness of calcium carbonate is less than 1000 mesh, it may appear dull in luster, rough in appearance, and reduced in strength of the finished product. If the amount of calcium carbonate used exceeds 10%, the appearance of the finished product will be dull and grayish white, with insufficient blackness, resulting in a decrease in the strength of the finished product. Secondly, in any outdoor product with anti-aging requirements, containing calcium carbonate is not good, and whether to use it depends on the lifespan of the product.

Article source: Taishan conductive mica particles

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