1. Field of the Invention
The present invention relates to a film derived from a linear low density polyethylene and used for stretch packaging.
2. Description of the Related Art
Stretch packaging methods have been proposed in which packaging is performed by winding stretchable band-shaped plastic film around articles to be packaged while stretching the films according to known stretching methods (e.g., Japanese Examined Patent Publication (Kokoku) Nos. 57-13442 and 58-7524). In these methods, highly stretchable stretch films are used to effect high stretch packaging or irregular shape packaging.
Examples of such films used for stretch packaging in the prior art are low density polyethylene, ethylene/vinyl acetate copolymer, and linear low density polyethylene.
According to the prior art methods, the stretch packaging machines stretch films by only about 30% during packaging, and recently, to reduce packaging costs, a stretch packaging machine capable of stretching a film by about 300% has been proposed. But, a single layer or composite stretch film composed of the above-mentioned low density polyethylene or ethylene-vinyl acetate can be stretched to a limit of about 150%, and therefore, a problem arises in that the film may be broken at a higher degree of stretching.
Also, in the case of a film composed of a linear low density polyethylene, the setting of the conditions for stretching by 300% or higher is severe, and even if stretching by 300% or higher is possible, too much stress may be applied to the packaged article after packaging, and thus the packaged article is deformed, or the film stretched to an irregular shape, whereby the appearance after packaging becomes undersirable. To solve this problem, the density of the linear low density polyethylene can be lowered, but if only the density is lowered, the starting material pellets or the film may become very sticky, thereby causing problems during the production thereof and in the handling of the packaged product after packaging. Also, although the stretch film has an inherent tackiness, an excessive tackiness will cause problems during the production of the film, and thus the film yield may be lowered.
USPTO Backgrounds
USPTO Backgrounds