JPS644698Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an easily tearable plastic sheet with tear lines formed thereon.

Prior Art Conventionally, in order to impart easy tearability to a plastic sheet, a tear line consisting of perforated holes or a cut groove of a certain depth has been provided. However, with these tear lines, dirt tends to adhere to the holes and grooves, leaving a dirty impression that cannot be removed.

Purpose of the invention The present invention aims to provide an easily tearable plastic sheet with tear lines that do not attract dirt.

Structure of the idea The present invention will be explained below based on the accompanying drawings.

FIG. 1 is a cross-sectional view of the easily tearable plastic sheet of the present invention, and FIG. 2 is a perspective view showing an example in which it is applied to a cap seal.

The easily tearable plastic sheet of this invention is the first
As shown in Figures 1 and 2, the creases 11 of the plastic sheet 1 are pressed to create minute crazes (cracks) 2 inside the plastic sheet to make it easier to tear, thereby making the creases 11 into tear lines. This is a characteristic feature.

As the plastic sheet 1, one made of polyvinyl chloride, polyethylene terephthalate, etc. can be used.

The creases 11 formed by folding this plastic sheet 1 may be pressed at a relatively low temperature with a predetermined pressure using a nip roll or the like to generate crazes 2 inside the thick wall. The temperature and pressure at this time vary depending on the resin constituting the sheet, but will be explained below using a sheet using polyvinyl chloride as an example.

Example: A heat-shrinkable tube made of hard polyvinyl chloride with a circumference of 100 mm and a wall thickness of 0.1 mm was heated to 35°C.
The material was passed through a pair of pressure rolls adjusted to a pressure of 85 kg/cm ² at a speed of 30 m/min while being pressed.

When this tube is sliced into thin rounds and observed under a microscope, as shown in Figure 1, crazes 2 are formed within the thickness of the tube (plastic sheet 2) 1, and the crazes 2 are exposed on the surface. It had a beautiful appearance.

Next, this tube was cut to a predetermined length to make a cap seal with tabs 3 provided on both sides of the crease line 11 at the upper end as shown in FIG. 2, and the mouth of the bottle was covered with heat shrink. The crease line 11 was smooth and free of dust and the like, and by pulling the tab piece 3, it was possible to tear cleanly along the crease line 11.

It is preferable that the cuts 31 between the tab pieces 3, which are continuous with the fold line 11, be provided deeply all the way to the top surface, since this will prevent the tube from becoming difficult to cut due to the increase in thickness of the tube due to shrinkage.

Effects of the invention As described above, the easily tearable plastic sheet of the present invention has a tearing effect due to the crazes formed within the wall thickness, so the tear line is smooth and it is excellent in that it does not attract dirt or the like.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the easily tearable plastic sheet of the present invention, and FIG. 2 is a perspective view showing an example in which it is applied to a cap seal. 1...Plastic sheet, 11...Fold line, 2...Craze.

Claims (1)

[Scope of utility model registration request] 1. An easily tearable plastic sheet, characterized in that the folds of the plastic sheet are pressed to generate fine crazes within the thickness of the plastic sheet to make it easier to tear, thereby making the folds a tear line.