What are the composite ways of plastic film?
Extrusion (casting, lamination) composite method refers to the PE or PP material after hot melt film extrusion, namely resin melting, extrusion pour in the plastic film, paper, aluminum foil, metal rolling drum vacuum aluminum plating film, the processing technology of the compound pressure after cooling. The composite product formed by pressing on the printing film is characterized by low cost and reduced glue pollution. But it is better to choose the type of extrusion material and control the extrusion temperature. In addition, a small amount of base rubber or AC agent is used as a coupling agent in the film. Extrusion (casting, lamination) composite method suitable for large quantities of varieties, but the film is not composite after (film above 0.05mm).
Wet laminating is the application of an adhesive (glue) to a film (foil), pressed together with a compound, and then dried by a drying oven. It is usually a composite method used in the composite processing of metal foil or plastic film and paper, and the water-soluble adhesive is used in the composite process.
Dry composite method is to glue (glue) coated on a plastic film, and then through the drying of the excess solvent evaporation, and then hot roller and another kind of plastic film pressed together, a composite processing technology. This kind of compound processing technology has great flexibility in batch and quantity, and can be used for compound processing of many varieties and multilayer films. Suitable for complex products, small batch, a wide range of packaging products, composite processing. This kind of processing method is especially suitable for our country's food and small food variety, the pattern is diverse, the batch quantity is few, renovates fast characteristic. The disadvantage of the processing method is that the composite thin film (below 0.02mm film) is not good, the cost is expensive, and the residual adhesive, flux and odor are easy to be left. The glue dry laminating machine itself oven length, heating mode, glue way, glue feeding control, tension control, temperature control and heat drum have cooling device determines its price and grade level. At present, a large number of domestic dry composite is the use of two-component adhesives, small manufacturers and individual products are also using a single component adhesive. Water soluble adhesives meet the requirements of environmental protection and no residual solvents, but the plastic and plastic composite has not been used in batches, but only when the wet combination of metal foil and paper is adopted. The single component adhesive is not suitable for food packaging because of its high odor, non curing, temperature resistance and complex bonding.In addition to the long-term use of PE film as the material of composite, especially PE film composite thick, with particular attention to PE (polyethylene) film surface tension, usually should be more than 42~52dyn to ensure the firmness of the film (recommend that the machine in the laminating machine is installed on the spark office).
The coextrusion process is the process of extruding a single resin or a variety of resins and extruding them through several molds to form a film (blown into film or cast into film). This composite does not use adhesives, so the composite film will have no residual solvents.
The solvent free composite method is a plastic film with pre - coated hot melt adhesive. Press the rollers together with another layer of plastic film. This way, less pollution, energy saving and energy-saving composite section, is the direction of future development. However, because of the high cost of solvent free composite equipment, as well as composite glue and technical reasons, there is still very little domestic use.
