JP2015089612A - Method of producing packaging bag and packaging bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the configuration in which only one side is a porous surface and pores directed upward during loading are eliminated prevents invasion of water from above but tends to prevent escape of gases lighter than air.SOLUTION: When a porous surface is formed by superimposing tubular films through fusion by laser irradiation, adhesion of the front and back surfaces possibly becomes poor. So the front and back surfaces are separated from each other immediately after irradiation of the laser beam, and fusion of the films is progressed. When cooled to such an extend that fusion does not occur, the film body is caused to be adhered flatly by using a pinch roll so as to prevent fusion. Air vents of pore diameters of 100-500 μm having deaeration performance are formed on one of the front and back surfaces, and in the other of the front and back surfaces, superfine pores of a pore diameters of 100 μm or smaller which prevent invasion of water but allow ventilation are formed.

Description

TECHNICAL FIELD The present invention relates to a method for producing a tubular film having a hole used for packaging rice grains having a hole for degassing, fertilizer, and the like, and a packaging bag produced using the method.

As a manufacturing method of the packaging bag, there are a method in which two films are bonded together and a method in which both ends of the film are bonded in a tube shape to form a bag.

Taking rice grains as an example of the use of these bags, polished rice is filled into a packaging bag made of a film for each predetermined weight, and the content inlet is sealed and then transported and stored. When it was stacked with air remaining inside the packaging bag at the time of sealing, it was the cause of bag breakage and collapse. In order to prevent this, a bag is generally provided with a deaeration hole.
As a method of opening, drilling with a needle as shown in Patent Document 1 and drilling with laser irradiation as shown in Patent Document 2 are performed.

When opening parts are provided on both sides of the packaging bag as shown in Patent Document 1, when the packaging bags filled with the contents are stacked, if the placement surface is wet with water, the inside of the packaging bag Moisture easily penetrates into. In order to prevent this, it is conceivable to make the holes small enough to prevent the ingress of moisture, but a large number of holes are required to ensure deaeration, leading to deterioration of the bag strength. Furthermore, in the case of opening by laser irradiation, the productivity is deteriorated due to an increase in the number of times of irradiation. So far, this problem has been addressed by making holes on only one side.

Japanese Patent No. 3816468 JP 2011-25678 A Japanese National Patent Publication No. 3-505063

Although the opening surface is one side and the hole on the surface facing upward during loading is eliminated, the intrusion of moisture from above can be prevented, but the structure is designed to prevent gas lighter than air from escaping. There was a problem that it became difficult to dry due to the filling of water and the location where water vapor escapes when the contents were wet.

In order to solve these problems, a ventilation hole with emphasis on deaeration of 100 μm to 500 μm is provided on one of the front and back surfaces of the packaging bag, and the other is 100 μm or less capable of venting while preventing water from entering the inside. The ultra fine opening hole is formed. By providing ultra-fine holes, it is possible to promote the discharge of gas that is lighter than the water vapor inside the packaging bag or the full air.

When using a needle as shown in Patent Document 1 as a means of opening, it is possible to make holes on the front and back surfaces simultaneously, but make a desired ultra-fine hole, and provide a difference between the front and back sides. It is difficult to make a hole.

In addition, in the case of opening with a conventional laser, for example, when opening on both sides is performed in the configuration shown in Patent Document 2, variation in film thickness and position when passing through the film due to the separation of the front and back surfaces Due to the instability of the laser, laser irradiation to the back surface cannot be performed stably. Although it is possible to use two laser irradiation devices as in Patent Document 3 and simultaneously open holes on both sides while the film is in progress, it cannot be easily introduced with an increase in the size of the manufacturing apparatus.

Therefore, it was decided to carry out hole opening with a laser with one laser irradiation device in a state where the front and back sides overlap. The aperture size is adjusted by adjusting the laser irradiation focusing position and the laser irradiation output. When the hole is opened by overlapping the tube-like film by melting by laser irradiation or the like, the front and back surfaces are separated immediately after irradiation at the laser position, but the film is advanced. Welding was prevented by flatly using a pinch roll when it was cooled to such an extent that welding did not occur.

It is the schematic of the tubular film manufacturing apparatus which concerns on embodiment of this invention.

FIG. 1 shows a film manufacturing apparatus in which the present invention is implemented. An embodiment of the present invention will be described with reference to FIG.

The target film raw material is supplied from the hopper 1 to the extruder 2. In the extruder 2, the resin is melted at a high temperature and kneaded inside to perform extrusion. The resin extruded into the extruder 2 is extruded vertically upward by the mold 3. The resin extruded from the mold 3 is cooled by air ejected from a ring-shaped slit inside the cooling device 4, and at the same time, the resin is stretched in the vertical direction while expanding by an internal pressure to form a thin tube-shaped resin film 5.

There is a pinch roll 7 for pulling up the tubular resin film 5 at the top of the film manufacturing apparatus, and a stable structure for folding the cooled and solidified tubular resin film 5 into a flat sheet under the pinch roll 7. A plate 6 is attached in parallel to the pinch roll 7. The resin film 5 fed upward and folded from the tube shape to the flat shape by the stabilizer 6 is brought into close contact with the front and back by the pinch roll 7 and again sent vertically upward through the guide rolls 8, 9 and 10.

When the film is fed vertically upward from the guide roll 10, a holding plate 12 is installed on the opposite side of the laser irradiation device 11 with the film interposed therebetween, so that the film at the time of progress is stabilized so as not to shake at the laser irradiation position. Above that, guide rolls 13 for sending the films separated from each other again are installed, and a separating tool 14 for separating the films is installed at the first passage of the film. Here, the guide roll 13 is intended to send the film separated by the separating tool 14, and is separated with a width that allows the separated film to pass therethrough.

The holding plate 12 is installed so that laser irradiation can be performed immediately before the film adhered by the separating tool 14 and the guide roll 13 starts to open. The purpose is to perform laser irradiation from the laser irradiation device 11 to melt and penetrate the front and back of the resin film 5, and to separate the overlapped front and back without welding. While the separated film is sent upward, the temperature drops below the temperature at which welding can be performed, and re-welding is prevented.

After passing through the guide roll 13, the front and back surfaces of the resin film 5 are brought into close contact with the pinch roll 15, the direction is adjusted with the guide roll 16, and the roll is wound up by the winder 17.

1 Hopper
2 Extruder
3 Mold
4 Cooling device
5 Resin film
6 Stabilizer
7 Pinch roll
8,9,10 Guide roll
11 Laser irradiation machine
12 Retaining plate
13 Guide roll
14 Separation tool
15 Pinch roll
16 Guide roll
17 Winder

Claims (2)

After flattening the tubular film with a pinch roll, it proceeds vertically to the horizontal, and it pierces on both sides of the film by irradiating the front and back of the film surface with laser irradiation from either front or back side. In addition, a tubular film manufacturing method is characterized in that a separator for separating the surface of the film is placed in the path, and welding is prevented by separating the front and back immediately after laser irradiation. A packaging bag formed from a plastic film formed in a tube shape, wherein holes having different sizes of holes having a size of 100 μm to 500 μm and holes having a size of 100 μm or less are formed at opposite positions on the front and back sides according to claim 1.

Images