How many production processes are available for stretch film？

Stretch  film is a new type of packaging material. The use of stretch  film for product packaging can effectively reduce the use cost. The use of stretch film is only about 15% of the original box packaging, about 35% of the heat shrinkable film, and about 50% of the carton packaging. There are many advantages to use stretch  film packaging, but do you know what the production process of stretch  film is?

Casting process

First, pour the raw materials into a container, and then use the suction pipe to suck them into the tape casting machine. During this process, the raw materials poured into the container should not be large solids. Make sure that the raw materials are clean, and prevent the produced stretch  film from being unqualified due to other particles. Next, the raw materials entering the tape casting machine are processed. The temperature here must be strictly controlled to prevent the production of unqualified stretch  film, which is then drawn by cooling with a cold roll. Then, roll up the stretch film produced by the  casting machine, and the stretch film roll is completed. In the process of extrusion casting and cooling shaping, there is no longitudinal stretching or transverse stretching. The thickness of the stretch  film formed by tape casting is even and transparent than that of the blow molded stretch  film.

Blow molding process

The stretch  film produced by blow molding is usually manufactured by extrusion blow molding. The material is plasticized and extruded to form a tube blank, which is then cooled, pulled and rolled. In blow molding film, the flat extrusion and upper blowing method is widely used. Production process of blown film by up blowing method: heating → feeding → extrusion → material lifting → roller feeding → inflation → adjustment → coiling → packaging → finished product.

The blow molding process is simple and easy to control. If there is no special requirement to add any plastic additives, the tensile stretch film produced by blow molding process has higher elongation at break than that produced by casting process.

Extrusion film forming process

The common extrusion film forming processes are unidirectional stretching and biaxial stretching. The basic principle of the biaxial stretching technology is that the polymer raw materials are first heated, melted and extruded into thick sheets through an extruder, and then, within the appropriate temperature range above the glass transition temperature and below the melting point, a certain number of times of stretching are successively carried out along the longitudinal and transverse directions through the stretching machine, so that the molecular chains are oriented and orderly arranged on the plane parallel to the film, and then heat setting is carried out under the tension state to fix the oriented macromolecular structure, Finally, the film is formed after cooling and subsequent treatment.

If you want to know more about the production and use of stretch film, please contact us, and we will provide you with a more comprehensive introduction.