Polyethylene thermal shrinkage film

Abstract

The invention relates to a polyethylene thermal shrinkage film, and belongs to the technical field of polyolefin films. The polyethylene thermal shrinkage film is characterized in that the thickness of the thermal shrinkage film is 50-60[mu]m; the thermal shrinkage film comprises an inner layer, a middle layer and an outer layer; in the inner layer and the outer layer, the mass ratio of metallocene polyethylene resin is 1 / 2-1 / 3, and the mass ratio of each of low-density polyethylene and high-density polyethylene is 1 / 4-1 / 3; in the middle layer, the mass ratio of the metallocene polyethylene resin is 1 / 2-4 / 5, and the mass ratio of the low-density polyethylene and / or the high-density polyethylene is 1 / 4-1 / 5; and the metallocene polyethylene resin is a copolymer of ethylene and alpha-olefin, the density is 0.930-0.940g / cm<3>, and the melt mass flow rate is 0.3-1.0g / 10min. By adding the specific metallocene polyethylene resin, the shrinkage performance of each layer is more coordinated; and the shrinkage performance and mechanical properties of the polyethylene thermal shrinkage film are ensured at a lower thickness.

Description

technical field [0001] A polyethylene heat shrinkable film belongs to the technical field of polyolefin films. Background technique [0002] Heat shrinkable film, commonly known as shrinkable film, is a film that can shrink greatly after being heated, so it can tightly wrap objects and maintain its shape for a long time. The heat-shrinkable film is designed by the principle of polymer molecular chain stretching and orientation, and is formed by rapid cooling and setting. The physical principle is: when the plastic raw material is heated and plasticized and extruded into a mother film, the polymer is forced to stretch along the vertical and horizontal directions between the glass transition temperature and the viscous flow temperature, so that the molecular chain of the polymer is stretched along the stretching direction. Orientation, and then the polymer is quenched, and the molecular orientation is frozen. When the film is reheated to the "thawing" temperature, stress rel...

AI Technical Summary

Problems solved by technology

[0003] In the early stage, most polyethylene heat-shrinkable films on the market were processed and produced by using low-density polyethylene alone or blending high-density polyethylene and low-density polyethylene. Although heat-shrinkable films have high shrinkage and mechanical properties, film products are relatively Thick, usually more than 100μm, and poor transparency, affecting the appearance of the packaged goods