A kind of polyethylene film

Abstract

The invention relates to polyethylene for a film, and belongs to the field of polyolefin films. The polyethylene is characterized in that the polyethylene is formed by copolymerization of ethylene and alpha-olefin in the presence of a supported metallocene catalyst, wherein the supported metallocene catalyst is composed of a bridged or unbridged metallocene compound and a cocatalyst which are supported on a porous carrier; the metallocene compound contains one or more eta-ligands; the metal is a Subgroup 4, 5 or 6 metal; the cocatalyst is a methylaluminoxane compound or modified methylaluminoxane; the carrier is an inorganic oxide, an inorganic chloride or a mixture thereof; the density of the polyethylene is 0.930-0.940g / cm<3>; and the melt mass flow rate of the polyethylene is 0.3-1.0g / 10min. The polyethylene composition is used for reducing the thickness of the film during thermal shrinkage film production and improving the comprehensive properties.

Description

technical field [0001] The invention discloses polyethylene for film and belongs to the field of polyolefin film. Background technique [0002] Heat shrinkable film, commonly known as shrink 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 rela...

AI Technical Summary

Problems solved by technology

[0003] In the early stage, most polyethylene heat shrinkable films in the market were processed and produced by using high-pressure polyethylene alone or blending high-density polyethylene and high-pressure polyethylene. Although the heat-shrinkable film has high shrinkage and mechanical properties, the film product is thicker. Usually more than 100μm, and the transparency is poor, which affects the appearance of the packaged goods

There is currently a lack of a polyethylene resin for films that is specially used for heat-shrinkable films, which can effectively reduce the thickness of the film while ensuring heat-shrinkable performance and mechanical properties.