Film for wrapping

Abstract

A film having a large tensile stress in the machine direction, excellent mechanical properties and stretch-wrapping property, and that is less broken at the time of wrapping, can be favorably torn off in the transverse direction, can be intimately adhered on the container walls to be wrapped, and excellently restores its shape after it is depressed and deformed as a result of wrapping. The film for stretch-wrapping is formed of a resin composition containing, as a chief component, an ethylene / (meth)acrylic acid / (meth)acrylic acid ester terpolymer that contains not more than 7% by weight of a (meth)acrylic acid ester unit, and, optionally, containing an anti-fogging agent or a tackifier.

Description

TECHNICAL FIELD This application claims priority to Japanese Patent Application No. 11-103239 field on Apr. 9, 1999, which is incorporated herein by reference. The present invention relates to a film for stretch-wrapping. More particularly, the invention relates to a film for stretch-wrapping comprising chiefly an ethylene-(meth)acrylic acid-(meth)acrylic acid ester terpolymer or a metal salt ionomer thereof. BACKGROUND ART PVC films have heretofore been chiefly used as stretchable films (for wrapping foamed polystyrene trays containing foods) for business use such as in supermarkets and convenience stores. However, from the environmental viewpoints in recent years, it has been urged to provide a substitute for the PVC. In the field of stretchable films for stretch-wrapping, the PVC films have rapidly been substituted by the olefin resin films. Many films for stretch-wrapping have so far been proposed using an ethylene / unsaturated carboxylic acid copolymer, an ethylene / unsaturat...

AI Technical Summary

Benefits of technology

It is therefore an object of the present invention to provide a film constituted by the above-mentioned terpolymer or an ionomer thereof, having a large tensile stress in the machine direction, excellent mechanical properties and stretch-wrapping property, i.e., to provide a film for stretch-wrapping that is less broken at the time of wrapping, that can be favorably torn off in the transverse direction, that can be intimately adhered on the container walls to be wrapped, and that excellently restores its shape after it is depressed and deformed as a result of wrapping.

Another object of the present invention is to provide a film for stretch-wrapping that can be easily formed and easily treated, that is homogeneous even optically, exhibiting less external haze and enabling the content to be seen through.

A further object of the present invention is to provide a film for stretch-wrapping, which suppresses the gelling tendency when it is blended with an anti-fogging agent without impairing the appearance or without being foamed during the working.

The film for stretch-wrapping can be prepared by the inflation method. However, the terpolymer used in the invention can be molded into a film by the T-die method offering an advantage that the film can be produced at a high speed.

This ionomer, too, has an advantage that it can be molded into a film by the T-die method.

Problems solved by technology

There have been described that the above bipolymer alone or the terpolymer alone exhibits a 100% tensile stress that does not lie within a suitable range (110 to 170 kg / cm2 in the machine direction of the film, and 60 to 110 kg / cm2 in the transverse direction), and is not suited for the automatic wrapping.

However, these two copolymers are not necessarily compatible to each other and, hence, the external haze value tends to increase.

Therefore, the film is not still satisfactory from the standpoint of seeing through the wrapped content.

When the ionomers of the above-mentioned copolymers are used, however, gel tends to be formed during the molding operation with the passage of time, making it difficult to prepare the film itself.