Requirements For Polyethylene Film

According to different processing methods, it can be divided into blown film, cast film and extrusion coating film. The thickness of the composite polyethylene film can be selected according to the requirements of the packaged material. The thinner can be about 20um, and the thicker can be greater than 100um. Since there are many additives in the resin used in the production of films, especially slip agents, the migration of additives should be paid attention to during production. The processing technology of the film is different, and the resin requirements are also different. The resin used for blown film has a melting index (mi) of 1 to 4; the resin used for cast film and extrusion coating has a melt index (mi) of 6. ~10. For packaging materials that require high heat sealing strength, six-carbon linear, eight-carbon linear and low-density polyethylene blends can be selected.

The metallocene polyethylene introduced in recent years can be said to be a revolution in polyethylene resin. First of all, Exxon of the United States invested in industrial production. Because metallocene polyethylene can set the molecular size, the molecular weight distribution is very narrow, and the density is between 0.9 and 0.93, so that the film made of metallocene polyethylene has good thermal adhesive strength and heat sealing strength. It has certain anti-sealing pollution performance. At present, the film produced by blending metallocene polyethylene and low-density polyethylene has been widely used in oil bags, shampoo bags, and washing powder bags. At present, most of the heat-sealing layer of composite packaging is made of polyethylene, such as instant noodles, biscuits, mustard and pickles. Blown film and cast film need to be processed by electric spark in the processing process, so that the surface tension of the film is greater than 38dyn/cm.