What is the Common Production Process of Plastic Films?

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Plastic film production process refers to the process of plastic raw materials into plastic films, soft film and rigid film, including raw material preparation, melting, extrusion, cooling, stretching, rolling. The common production process of plastic films include extrusion, blowing, calendering, casting and stretching.

1)   Extrusion process

Extrusion process is adding the plastic resin and additives into the extruder, heating and melting and extruded to be film sheet, which is quickly cooled and shaped, trimmed and then rolled. PET film is made of extrusion process .

2)   Blowing process

The blowing film is molten resin extruded and made into tube blank through the annular gap head. Meanwhile, compressed air is introduced from the axial direction of the mandrel, a pair of clamping rods clam the tubular membrane to maintain constant pressure, until expand to the desired diameter, then rolling after cooling and shaping. The blowing method include tubular film like LDPE tube film, LLDPE tube film and waterproof breathable TPU film.

3)   Calendering process

Calendering process is a method which the polymer is continuously formed into a thin film through the gaps of several rollers. The thickness of the film depends on the gap of the last set or rollers. The calendering process is commonly used in the production of flexible PVC film.

4)   Casting process

Firstly, dissolve the plastic resin in an organic solvent with a concentration of 10%-35%, after filtering and defoaming, then send to the casting machine to make the solution flow through the casting nozzle, and stretch to the desired thickness.  The casting process is commonly used in the production of TPU film and EVA film.

5)   Stretching process

Stretching process is stretching the thermoplastic plastic film in both vertical and horizontal directions. The stretching proves of plastic films is divided into uniaxial stretching and biaxial stretching, like BOPP film, BOPET film.

Different plastic film, with different production process. Each step of production process, requires precise control parameters to ensure excellent performance and quality of the plastic film.