Factors affecting the transparency of blown film in blown film machines and corresponding measures
The commonly used blown film raw material for blown film machines is polyolefin, which is a highly crystalline polymer. Therefore, the important factor affecting transparency is the resin raw material. Of course, improving the quality of the blown film machine is also a consideration, but the technology of the blown film machine itself has little impact on the transparency of the blown film. Transparency refers to the percentage of transmitted light intensity with a scattering angle less than 0.1 ° to the incident light intensity when the incident light passes through the sample. The higher the transparency of the film, the clearer the image when viewed from a distance through the film. Transparency is related to the crystallinity and surface smoothness of the film. The lower the crystallinity, the more amorphous areas there are, and the smoother the surface, the higher the transparency usually.
It can be seen that a better method to improve the transparency of thin films is to use lower crystallinity and small spherical crystals. This can reduce the surface tension of the film, thereby lowering the thickness of the film. In addition, adding a certain amount of plasticizer to the film can also improve its transparency. Even the most advanced blown film technology can only improve transparency to a certain extent.
How to solve the problem of blown film transparency when the raw materials are relatively good? Firstly, it is necessary to consider that the extrusion temperature of the blown film machine is too low, resulting in poor plasticization of the melt. To solve this problem, simply increasing the melt temperature is usually sufficient. Another point is that poor cooling after blown film can also affect transparency, and the corresponding mechanism is to increase the cooling air volume.
Returning to the raw materials of the blown film machine, the high moisture content of the resin balls can also affect the transparency of the blown film. This problem is relatively simple, as long as the resin balls are thoroughly dried. But if it is glass fiber, special treatment is needed, such as coating a layer of transparent protective film on the surface of the resin ball, which can prevent the resin ball from reducing transparency due to excessive moisture.
The above is the relevant content about the blown film machine. In summary, the factors that affect the processing technology of thin films include cooling, raw material polyethylene resin parameters, additives, temperature, and formula design. By analyzing different problems specifically, they can be easily solved.
It can be seen that a better method to improve the transparency of thin films is to use lower crystallinity and small spherical crystals. This can reduce the surface tension of the film, thereby lowering the thickness of the film. In addition, adding a certain amount of plasticizer to the film can also improve its transparency. Even the most advanced blown film technology can only improve transparency to a certain extent.
How to solve the problem of blown film transparency when the raw materials are relatively good? Firstly, it is necessary to consider that the extrusion temperature of the blown film machine is too low, resulting in poor plasticization of the melt. To solve this problem, simply increasing the melt temperature is usually sufficient. Another point is that poor cooling after blown film can also affect transparency, and the corresponding mechanism is to increase the cooling air volume.
Returning to the raw materials of the blown film machine, the high moisture content of the resin balls can also affect the transparency of the blown film. This problem is relatively simple, as long as the resin balls are thoroughly dried. But if it is glass fiber, special treatment is needed, such as coating a layer of transparent protective film on the surface of the resin ball, which can prevent the resin ball from reducing transparency due to excessive moisture.
The above is the relevant content about the blown film machine. In summary, the factors that affect the processing technology of thin films include cooling, raw material polyethylene resin parameters, additives, temperature, and formula design. By analyzing different problems specifically, they can be easily solved.
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