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Characteristics of Extrusion Technology of Multi-layer Co-extruded Cast Film
  • 2018-09-27 17:04:19

The multi-layer co-extruded cast film extrusion technology is a conventional film extrusion production process. The biggest advantage of this process is the extremely high machining accuracy and the ability to maximize the performance of the material being processed. Especially in the processing of high barrier multi-layer co-extruded cast film, it has unparalleled advantages.


The multi-layer co-extruded cast film extrusion technology is a composite die in which two or more different plastics are passed through a multi-channel extruder using two or more extruders to join a multi-layer structure. Composite film technology for forming by chill roll. The multi-layer co-extruded cast film extrusion technology is also a conventional extrusion production process for producing Thermoforming Film.


This method can produce films of various materials and has high processing precision, especially when processing semi-crystalline thermoplastics, this processing method can fully exert the performance of the material to be processed while maintaining the most good dimensional accuracy. Thus the cast film has excellent optical properties and thickness uniformity, and a high production speed can be obtained by using a chill roll, and the morphological structure of the PA/PE Lidding Film is improved.


Compared with other films (such as blown film), the film prepared by the method has the advantages of high production speed and high output, and its favorable for mass production; the thickness control precision of the product is high, the thickness uniformity is good; transparency and gloss excellent performance; excellent balance performance. The general method or even the only method for processing certain materials, such as polypropylene (PP) film, polyester film (PET) film, which is the only multilayer coextrusion casting method.


The main technical features of the multi-laye casting coextrusion are:


     ●Precise control of mixing and conveying of various raw materials and auxiliary materials;


     ● 2 or more extruders for co-extrusion;


     ● The co-extruded melt is extruded through a T-shaped flat die and then quenched and re-solidified on a large-diameter chill roll to form;

     ●The design of the multi-layer co-extrusion compound die enables the layers of the melt to be evenly distributed after the die is unfolded, and prevents the mutual entanglement between the materials of the layers;


     ● It can accurately monitor and adjust the overall thickness, and accurately monitor and adjust the thickness of certain key functional layers.


     ● The automatic control system of the equipment is very complicated, such as mixing and conveying of raw materials, temperature control, speed control, co-extrusion control, thickness uniformity control, etc., and the control of the process is also quite complicated.


     ●Compared with the dry composite technology, the multi-layer co-extruded cast film extrusion technology can greatly reduce the production cost, achieve clean and safe production, and the hygienic reliability of the product is best.


Since the multilayer Coextruded Cast Film is a multilayer composite film directly obtained by one-step processing. Therefore, the multilayer co-extruded cast film has the advantages of less production process, less energy consumption, and lower cost than the dry composite film method.


In general, the use of multi-layer co-extrusion casting film formation compared to the most commonly used dry composite film formation, production costs can be reduced by 20% to 30%, while the structural quality of the product is better and more stable. In the production process of multi-layer coextrusion casting, no three waste materials are produced, which will not pollute the surrounding environment and have good adaptability to environmental protection.


At the same time, due to the use of substances such as flammable and explosive organic solvents in the production process, production safety is also good. In contrast, the commonly used dry composite film-forming method uses and discharges a large amount of organic solvents in the production process. These solvents are more or less harmful to people's health, and are often flammable and explosive. Dangerous, need to be handled properly.


In the multilayer coextrusion casting production process, since the organic solvent and the binder are not used, in the multilayer coextruded cast film, the problem of residual solvent does not occur like the dry composite film.


In addition, the multi-layer co-extruded cast film is produced in one step, and the intermediate product of the composite film is not required to be manufactured in advance, thereby avoiding the hygienic performance degradation caused by the contamination of the semi-finished product during the storage and transportation process, thereby making it Has better hygiene and reliability.

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