Linearly easy-to-rupture thermoplastic resin film, and method and device for manufacturing the resin film

Abstract

A method for forming substantially parallel linear scratches on a thermoplastic resin film, comprising bringing the film into sliding contact with a means having a lot of fine projections for forming linear scratches, and pressing the film onto the linear-scratch-forming means from the opposite side of the linear-scratch-forming means by a film-pressing means, in a region in which the film is in sliding contact with the linear-scratch-forming means.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a thermoplastic resin film easy to straight tear in one direction, and a method and apparatus for producing such a film. BACKGROUND OF THE INVENTION [0002] In recent progress of barrier-free items, easy opening is considered to be an important function for wrapping films. Typical methods for making the wrapping bags easily openable include a method of providing the wrapping bags with cutting-start points such as V-shaped notches, etc. in their edge portions (heat-sealing portions), and methods needing no cutting-start points such as a magic cut method, a fancy cut method and a method of providing the wrapping bags with fine pores. [0003] The magic cut and the fancy cut comprise providing the wrapping bags with fine scratches in their edge portions and bending portions in place of notches. However, even with the magic cut or the fancy cut, it has been difficult to open the wrapping bags straight in directions not aligned ...

AI Technical Summary

Benefits of technology

[0008] Accordingly, an object of the present invention is to provide an inexpensive thermoplastic resin film easily torn straight in one direction regardless of the orientation of the original film, free from the above-mentioned defects of the conventional films.

[0012] Thus, the easy-to-straight-tear thermoplastic resin film of the present invention has substantially parallel linear scratches formed at least on one surface, so that it is easily torn straight from any point along the linear scratches.

[0014] The easy-to-straight-tear thermoplastic resin film of the present invention may further have a lot of fine penetrating and / or non-penetrating pores uniformly. The easy-to-straight-tear thermoplastic resin film of the present invention may be a single-layer film or a laminate film. The laminate film preferably has at least one film layer having the linear scratches, and a sealant film layer.

[0017] In one preferred embodiment of the present invention, the film-pressing means is an air-blowing means. Air blowing makes it possible to apply a substantially uniform pressure onto the film surface in sliding contact with the linear-scratch-forming means. The pressure of an airflow blown onto the film is preferably 0.05 to 5 kgf / cm2. Preferable as an air-blowing means is a blower or a nozzle.

Problems solved by technology

However, even with the magic cut or the fancy cut, it has been difficult to open the wrapping bags straight in directions not aligned with the molecular orientation of plastic films.

Further, when cut lines progress in conventional easy-to-open wrapping bags beyond their edge portions to regions in which contents are included, the cut lines are likely to unintentionally go toward the regions having contents even though plastic films for the bags have molecular orientation, resulting in falling, dropping or scattering of the contents.

However, because the vapor-deposited transparent films are composed of thermoplastic resin films vapor-deposited with metals, metal oxides, etc. and coated with resins, they have insufficient easy-to-tear characteristics even though the plastic base films have easy-to-tear characteristics.

As a result, the films cannot be moved at a high speed in the production of the wrapping films, resulting in low productivity and high production cost.

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