Common composite methods and characteristics of plastic film.

2024-07-31

    Flexible packaging occupies a very important position in the packaging and printing industry, and composite packaging made of plastic film is widely used in various fields such as medicine and food. The composite bag made of plastic film, because of its low price, high quality, excellent heat sealing, barrier property, acid resistance, alkali resistance, leak proof and other characteristics to meet the needs of different levels of packaging. Today, let's take a look at what kinds of composite plastic films there are and their respective characteristics.

1, dry compound method

     Dry composite is made by stacking two or more materials together at high temperatures and forming a whole after pressure and heat treatment. This composite processing technology has great flexibility for batch and quantity requirements, and can be used for composite processing of multi-variety and multi-layer films.

      Dry composite can achieve a solid bond between materials, improve the strength and hardness of the product; The preparation process of dry composite does not need to use any harmful solvent, which is more friendly to the environment. Dry composite can realize the composite of a variety of materials, making the performance of the product more diversified.

       However, the shortcomings of dry composite are also obvious, the need for high temperature pressure, high equipment cost, and the preparation process is relatively complex. Due to the need for high temperature heating, the performance of some materials may be reduced, the size and shape of the product is limited, and it is difficult to achieve large-scale applications.

      This kind of processing method is especially suitable for the characteristics of food and small food varieties in China, less batch and fast renovation. At present, two-component adhesives are widely used in domestic dry composite, and small manufacturers and individual products also use single-component adhesives. Water-soluble adhesives meet the requirements of environmental protection, and there is no solvent residue, but the composite of plastics and plastics has not yet been used in batches, but it is only used in the wet composite of metal aluminum foil and paper. The smell of single-component adhesive is large, non-curing, non-temperature resistance, and the compound is firm and poor, and it is not suitable for use in food packaging.

2, wet compound method

      The wet compounding method is to apply the adhesive (glue) to the film (foil), press together with the composite, and then dry through the drying channel. It is usually a composite method used in the composite processing of metal aluminum foil or plastic film and paper, and a water-soluble adhesive is used in the composite.

3, extrusion (casting, film) compound method

      Extrusion (casting, coating) compound method refers to the PE or PP material after hot melt extrusion film, that is, the resin is melted, extrusion on plastic film, web paper, rolled metal aluminum foil, vacuum aluminized film, after pressing and cooling composite processing technology. The composite product formed by hot pressing composite on the printing film is characterized by low cost and reduced glue pollution. However, it is necessary to choose the model of the extrusion material and control the extrusion temperature, and the effect of adding a small amount of primer or AC agent as the coupling agent between the film will be better. The extrusion (casting, coating) composite method is suitable for the production of large quantities of varieties, but it can not be the film after the composite (more than 0.05mm film).


4, co-extrusion method

    The co-extrusion method is a process in which a single resin or a variety of resins are melted and then extruded through several die heads to form a film (blown film or cast film). This composite does not use adhesives, so there is no solvent residue after the composite film.

Multi-layer co-extruded composite is a green composite production process, especially for the current food packaging industry, the raw materials generally used by the United States food and health and safety agencies certified materials, raw materials by a special feed pipe centralized unified feed for each layer, processing without raw material exposure, no environmental pollution and other phenomena. Its binding layer is the modified LLDPE as the raw material, which is not toxic to the environment, food and human body, and will not appear traditional dry compounding, that is, the so-called solvent residue phenomenon, no waste gas pollution; It is also different from dry composite, solvent-free composite and general single-layer extrusion composite processes, which require drying chambers for processing, so energy consumption is also less.

     In terms of application, multi-layer co-extruded composite products can cover almost all packaging fields: food, daily chemical products, beverages, pharmaceuticals, protective films and even aerospace products, etc. At present, many dry composite products in China have adopted co-extruded composite processes in foreign countries. Toothpaste tubes that cannot be produced by the dry compounding process. Paper-plastic aluminum composite products. Aerospace and other products are also used to achieve the co-extrusion composite process. With the in-depth research and continuous innovation of co-extruded composite resin, process and equipment, multi-layer co-extruded composite will be extended to a wider range.

5, no solvent compound method

      Solventless composite is a new process using polymer material film melting and bonding under high temperature and pressure, due to the use of solventless, the solventless composite process will not produce any pollutants, is a very environmentally friendly process. Moreover, in the process of solvent-free composite, the performance of the polymer will not be affected by external solvents, and it can maintain its own excellent performance. Solventless composite does not need to use additional toxic and harmful substances, and the operation is simpler and faster than traditional solvent composite.

      However, the cost is high, because the solvent-free composite requires sophisticated equipment and fine processes, so its cost is high, and some small and medium-sized enterprises are economically difficult to bear. And requires a higher processing temperature and a longer processing cycle, so its production efficiency is relatively low.

       In summary, this composite way of energy saving, energy saving, time saving, less pollution, is the direction of future development. However, due to the high cost of solvent-free composite equipment, as well as composite adhesive and technical reasons, it is rarely used in China.

Hunan Kexin Packaging Co., Ltd.
sale@kxpackage.com
86-19174886769
RM1124,Bld 1, Jinqiao International Weilai Town, Changsha, China
Leave a Message
*Email
*Message
Send
China Good Quality Plastic Pouch Bags Supplier. Copyright © 2023-2025 plasticpouchbags.com . All Rights Reserved.