Everything you need to know about the application of black master in plastic products

Table of Contents

As a professional in the field of plastics production, it is important to be aware of the latest advances in technology. In this blog post, we will discuss the use of black master batch in plastics production.

We will describe what black masterbatch is, how to use it, and its benefits. By understanding black masterbatch, you can apply it in your production process to achieve better results. So, let’s get started!

1. What plastic materials are black masterbatches 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 the international classification, there are more than 30 varieties in my country. It is mainly divided into two categories: rubber and non-rubber. In carbon black for rubber, it is mainly wear-resistant carbon black, which can effectively improve the wear resistance of rubber tires; in non-rubber carbon black, there are only a few carbon blacks that can be used as a black masterbatch. Channel black is the most widely used in plastics, mainly due to its abundant sources, high purity, and small particle size.

3. What is the carbon black carrier?

The carrier is the substance that carries the black carbon. Generally, what kind of raw materials are used for plastic injection molded products, and what kind of raw materials are used for the carrier?

Theblack masterbatch produced 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 selected, because LDPE has the strongest ability to carry carbon black and has good processability.

While other polyethylene HDPE and LLDPE can only manufacture low-concentration black masterbatch. For PP (polypropylene) plastic products, only black masterbatches with PP and LDPE as carriers can be used, but black plastic masterbatches with HDPE, LLDPE, and other plastics as carriers cannot be used. Of course, there are also black masterbatches that use recycled materials as carriers.

4. Why does carbon black need a wetting agent?

The specific gravity of carbon black is about 2g/cm2. Due to the small particle size of carbon black, the apparent density is very small, and it looks fluffy and light. For smooth processing, the carbon black must first be wetted.

The choice of wetting agent is critical. To reduce costs, there are not a few companies that use a large number of products such as white oil or paraffin, which will seriously affect the strength of the processed products.

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

There are two types of organic dispersants and inorganic dispersants. The high-grade black masterbatch uses organic dispersant, which is mainly used for plastic products with high environmental requirements.

Low-grade black masterbatches use inorganic dispersants, usually calcium carbonate. It can be judged from the color masterbatch packaging that only half a bag of 25 kg must use an inorganic dispersant; the full bag is a black masterbatch using an organic dispersant.

The use of inorganic dispersants can greatly reduce the plastic production cost of black masterbatch, but it is fatal that calcium carbonate has the effect of accelerating the aging of plastic products.

6. Do black masterbatches also need processing aids?

Of course, you need to. A smooth machining plastic processing requires the correct selection of antioxidants, internal lubricants, external lubricants, modifiers, and antistatic agents.

7. What are the processing methods of black masterbatch?

There are three kinds: single-screw method, twin-screw method, and ban burying method. Single-screw method: After mixing the materials with a mixer, the single-screw extruder is used to granulate the strands.

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, they are granulated by a twin-screw extruder or a water ring. Due to the limited mixing capacity of the twin-screw machine itself, the carbon black concentration of the master batch is generally 25-32%.

Banbury mixing method: use a mixer to mix the materials, add them to the Banbury mixer and knead them, then feed them into the twin-screw extruder from the feeder, and pelletize them through a 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. The ban burying man burying over the carrying capacity of the carrier to the 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 to break the agglomerated particles, the agglomerated particle size of the carbon black particles is greatly reduced, and the particle size and distribution of the carbon black in the masterbatch are uniforms, which cannot be replaced by the other two methods.

9. What are the outstanding performances of black masterbatch?

In terms of dyeing of plastic products, only 0.6%-0.8% of black masterbatch is needed, it will be extremely black, and it will not be darker if more is added.

According to the test data, if the products used outdoors in Xinjiang need to rely on black masterbatch for anti-aging, as long as high-quality black masterbatch is used (instead of recycled materials as carriers, white oil wetting, calcium carbonate dispersion, etc.), the content of carbon black in the product reaches 2-2.5%.

That is, for every 100 kg of raw materials, there are 5-6 parts (weight) of masterbatches containing 40% carbon black, which is far more effective than any anti-aging product, and the product life 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 the increase of product strength and electrical conductivity.

10. It seems that so many parts of black masterbatch are not used in actual production.

That’s right. In actual production, about 2 parts of black masterbatch are generally used, and anti-aging additives are added to reduce injection molded products costs by using the synergistic effect of anti-aging and carbon black to prevent aging.

In addition, the length of outdoor use and the requirements of product life also determine that the amount of black masterbatch used should be appropriately reduced, provided that 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 a high concentration of small pieces) will be discontinuous in the product.

At the boundary between phases and phases, the plastic molecules are the most fragile, and they will be directly hit by ultraviolet light to accelerate the oxygen aging reaction. When carbon black is like an impurity in the injection molded products, it is better not to add it.

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