Calcium carbonate filling masterbatch is a particle with a similar volume to the base resin of plastic products, which is made by mixing, mixing and granulating calcium carbonate and carrier resin. It has a wide application value in the plastic industry. Before the masterbatch processing, the surface of calcium carbonate powder is modified to increase its dispersion, which can greatly improve the cross-linking with the resin.  polyethylene wax for filling masterbatch

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However, there are still five problems needing attention in the production of calcium carbonate filling masterbatch:

1. Surface modification of calcium carbonate

In order to make the calcium carbonate particles in the filling masterbatch evenly dispersed into the matrix plastic, the calcium carbonate particles must be completely coated. If calcium carbonate has agglomerated in the process of producing filling masterbatch, the agglomerated particles cannot be opened in the extruder of blown film, which is bound to form many white spots on the film. Even white hard particles may form "clouds".

To solve the agglomeration problem of calcium carbonate particles, two aspects should be paid attention to:

(1)The first is to prevent excessive friction during surface treatment. Once static electricity is generated due to friction, it is very easy to agglomerate.

(2)Secondly, the amount of surface treatment agent should be sufficient. When the particle surface is changed to lipophilic by the action of coupling agent, its surface energy decreases greatly and it is not easy to agglomerate with each other.

2. Filling ratio of calcium carbonate

The higher the proportion of calcium carbonate in the filling masterbatch, the lower the raw material cost of the product and the more competitive it is in the market. Because the particle size of calcium carbonate is small, the number of particles is large, and the total surface area is also large, it needs more carrier resin to cover it, which requires not only small melt viscosity of carrier resin, but also sufficient amount.

In order to obtain film grade filling masterbatch with good performance, the weight percentage of calcium carbonate is generally not more than 80%, while the weight percentage of carrier resin is generally not less than 13%.

3. Physical mixing state

There are different views on what form the materials in the high-speed mixer should be stirred. Some people have tried to put the material after stirring it into a complete paste and only mechanically mixing it evenly, and put the material when the particles of the carrier resin still maintain the original particle shape. There is no obvious difference in the application effect of the filling masterbatch made in the two extreme cases in the film.

Our experience is that the best carrier resin has begun to melt and fully contact with the surface treated heavy calcium to form a pimple, but do not form a paste. At this time, put the material immediately. If the paste is formed, it is very difficult to discharge the material, which delays the time and reduces the production efficiency. If the material remains in the state of particles and powder, not only the components can not be uniform, but also the particles and powder are separated again when feeding into the twin-screw extruder, resulting in more heavy calcium and resin in the product, which will lead to uneven material during film blowing, "Clouds" or white spots are easy to occur.

4. Selection of extruder

The extruder used for material mixing, mixing and granulation is also very important. The co-directional parallel twin-screw extruder is far better than the single-screw extruder with mixing section, while the reciprocating single-screw extruder is better than the co-directional parallel twin-screw extruder in producing film grade filling masterbatch with ultra-fine heavy calcium as the main raw material.

The advantages of mixing and granulation equipment can make up for the shortcomings of calcium carbonate surface treatment in high mixer and initial mixing with carrier resin. Therefore, the selection and arrangement of manual extrusion mixing and granulation equipment and threaded sleeve are also very important.

5. Cooling method

In the granulation part, the operation mode of brace water cooling should be avoided as far as possible. Because of the level of manual operation and sense of responsibility, once the material carries water, it will bring major hidden dangers to the blown film. If polyethylene resin is used as the carrier resin, the air-cooled die surface hot cutting process is suitable. The shape and size of the particles are very particular. Generally, a disc with a diameter of 3 ~ 5mm is suitable, and its thickness is about 1mm. It is mainly for easy mixing with the particles of the matrix resin when blowing the film, rapid melting in a short time, and easy mixing with the matrix resin materials.

When the diameter of the extruder is large (e.g. the diameter is Φ 72mm and above), when the output is higher than 300kg / h, it is difficult to do a good job of the hot head of the air-cooled die surface, the temperature is not easy to control, the particles cannot be cooled down and are easy to adhere. At this time, the cooling mode of conveyor belt should be used, and this mode is suitable for the production of various filling masterbatch or modified special materials, but it needs a long distance cooling and requires a large site.

Qingdao Sainuo Chemical Co., Ltd. We are a manufacturer for PE wax, PP wax, OPE wax, EVA wax, PEMA, EBS,Zinc/Calcium Stearate…. Our products have passed the REACH, ROHS, PAHS, FDA testing. Sainuo rest assured wax, welcome your inquiry!

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