JP2000317663A - Method for perforating film sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suck away a small piece cut off by a laser beam and to prevent the generation of a build-up around a perforated hole by irradiating the front surface of a small-thickness film sheet with the laser beam to bore a small hole while bringing a jig having suction hole into direct contact with the rear side of the film sheet. SOLUTION: The film sheet 1 of PE, etc., is bored with the small hole 2 by laser beam processing. At this time, the jig 4 having the suction hole 6 is brought into direct contact with the rear side of the film sheet 1 and the front surface is irradiated with the laser beam in this state. The irradiation is preferably executed by moving the laser beam along the contour of the hole to be bored with the position where the contact part 5 of the film sheet 1 in direct contact with the jig 4 is irradiated with the laser beam as a start point. At this time, the jig 4 is cooled down to <=30 deg.C, more preferably about 20 to 10 deg.C. As a result, the cut off small piece is sucked away without allowing the small piece to fuse and remain at the film sheet body. In addition, the clean hole free of the build-up in the aperture may be bored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for making small holes in a film sheet by laser light treatment. In particular, the present invention relates to a method of providing a small hole having no cut in the opening and a uniform cut shape.

[0002]

2. Description of the Related Art As a packaging material used for a food and drink package cooked in a microwave oven, there is a material obtained by laminating a film sheet having no small holes on a film sheet having small holes (for example, JP-A-10-147381). . When food or beverage is enclosed in the packaging material and heated by a microwave oven, the temperature inside the package gradually increases, and the pressure also increases. When this pressure exceeds a certain value, the non-perforated film layer corresponding to the perforations of the perforated film layer is cleaved to release the excess pressure. And it has the feature that cooking can be performed at the optimum temperature and pressure for each food and drink.

[0003] The size of a small hole in a film sheet used for a food or drink package is about 4 to 10 mm in diameter. In order to provide a small hole in a film sheet, a mechanical method is generally used. That is, a film sheet is punched out using a blade having a size to be opened and a shape to be opened. However, this method has a thickness of 1
For a film sheet of 00 μm or more, the holes can be effectively punched, but the thickness is less than 80 μm, particularly,
When applied to a film sheet of 50 μm or less, there is a problem that the blade (male) bites into the receiving side (female) and it is difficult to make a hole.

[0004] Instead of a mechanical method, a method of forming a hole by laser light treatment is conceivable. That is, a method of irradiating a laser beam to a position of a hole to be opened and cutting out a portion corresponding to the hole of the film sheet to form a hole. However, when trying to make small holes by irradiating a thin film sheet with laser light, the temperature of the part irradiated with the laser light rises,
In the periphery of the film sheet to be perforated, the film sheet is in a molten state, small pieces to be cut out for perforation are fused to the main body of the film sheet, the small pieces cannot be removed, and the part irradiated with laser light is There is a problem in that the shape of the swelled and drilled holes is disturbed, resulting in an unnatural shape.

[0005] For example, FIG. In the case where the small holes 2 are provided in the film sheet 1, simply irradiating the laser beam causes the periphery of the small holes 2 to be melted to be in a state 3 in which the periphery of the small holes 2 is melted and shrunk. In addition, the small pieces to be removed when making the holes are fused to the film sheet, and the small pieces cannot be removed. That is, in FIG. 5 in which the small hole 2 portion is enlarged, the small hole portion to be cut out shrinks into a small piece 7, and the small piece 7 is fused to the film sheet and removed by suction from the suction hole 6 of the jig. You will not be able to. In addition, the shape of the holes becomes irregular, resulting in a decrease in commercial value when used in a food or beverage package, and when a film sheet having been perforated is wound up, the peripheral portion of the hole is raised, so that the film is raised. The roll of the sheet swells at a portion corresponding to the small hole, and has a problem that the efficiency of the subsequent work is reduced.

[0006]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned problem of piercing a small hole by irradiating a film sheet with a laser beam, and there is no swelling around the opened hole, so that the shape of the hole is beautiful. Accordingly, it is an object of the present invention to provide a perforation method in which small pieces to be removed can be easily removed by suction without fusing to a film sheet and remaining.

[0007]

According to the first aspect of the present invention, when a small hole is formed in a film sheet by laser light treatment,
On the non-laser light irradiating side of the film sheet, a part of a portion to be perforated is brought into direct contact with the surface of a jig having a hole for sucking a small piece of the film sheet to be cut off by laser light irradiation. And piercing the film sheet by irradiating a laser beam to the film sheet.

According to a second aspect of the present invention, a portion of the film sheet which is in direct contact with the surface of the jig is irradiated with a laser beam, and the laser beam is moved from the position along the contour of the hole to be drilled. 2. The method according to claim 1, wherein the film is irradiated to form holes. In the invention of claim 3, the temperature of the jig is set to 30.
3. The method for perforating a film sheet according to claim 1 or 2, wherein the temperature is set to not more than ℃.

The film sheet provided with the small holes according to the present invention comprises:
It can be used for food and drink packages cooked in a microwave oven. Examples of usable film sheets include polyolefin film sheets such as polyethylene film sheets and polypropylene film sheets, polyester film sheets, polyamide film sheets, polyvinyl chloride film sheets, polyvinylidene chloride film sheets and polystyrene film sheets. Further, a multilayer film sheet obtained by laminating these films can also be used.

When drilling is performed by laser light treatment, a work piece, dust, or smoke is generated, and it is necessary to appropriately remove these. Generally, these are sucked and removed by vacuum. That is, a small piece is cut out of a part of the film sheet in order to make a hole with a laser beam, and the small piece is removed by vacuum. At the same time, dust and smoke and soot are generated, which are also removed by vacuuming. At this time, a jig for vacuuming is provided.

The present invention is characterized in that a part of a film sheet is brought into contact with a jig used for vacuum-removing small pieces, dust, smoke and the like, and laser light treatment is performed.
Then, at this time, the laser light is first irradiated on the jig contact portion, and then the laser light is moved along the contour of the shape and size of the hole to be drilled, and reaches the position where the laser light is first irradiated, The irradiation of the laser beam ends. It is important to first irradiate the laser beam to the portion of the film sheet that is in contact with the surface of the jig. Further, the temperature of the jig itself affects the degree of drilling of the drilled hole. If the temperature of the jig is high, the drilled holes will be irregular, so it is preferable to keep the temperature below a certain temperature. In addition, the temperature of the jig gradually rises due to the irradiation of the laser beam, so it is preferable to appropriately cool the jig. From this viewpoint, the temperature of the jig should be at least 30 ° C.
It is better to: The temperature of the jig should be less than 20 ℃ and 10 ℃
It is particularly preferable to make the above.

Due to the laser light irradiation, the temperature of the film sheet is increased in the laser light irradiated portion. This is because heat generated by laser beam irradiation is accumulated. At the time point when the irradiation of the laser beam is completed, the accumulated heat amount is the maximum. The heat is accumulated most in the portion irradiated with the laser beam first. When this laser beam is simply applied to the film sheet, the film sheet around the opening is melted due to the accumulated heat, the shapes of the holes formed are irregular, and a bulge is formed in the opening. The small piece to be cut by the laser beam shrinks due to heat, becomes much smaller than the size of the hole to be actually drilled, and is fused to the sheet body.

On the other hand, if the film sheet portion where the amount of heat accumulates the highest is in direct contact with the surface of the jig, the accumulated amount of heat moves to the jig and the temperature rise of the film sheet is suppressed, As a result, it is possible to form a beautiful hole having a uniform shape and no swelling in the opening. At this time, the area of the film sheet portion to be brought into contact with the jig surface depends on the thickness of the film sheet to be perforated, the size of the perforated hole, etc., but is about 10% to 60% of the area of the perforated hole. .

On the other hand, if the portion of the film sheet to be perforated is completely in contact with the jig, the small piece to be cut is not removed by the laser beam, and the small piece to be cut is deposited on the jig. Therefore, even if the first few holes can be drilled, it is difficult to continue the drilling work after that, and the work may be interrupted.

Further, the temperature of the jig affects the degree of opening of the holes. It is preferable to lower the temperature of the jig appropriately. The temperature is 30 ° C. or less. The appropriate temperature depends on the thickness of the film sheet and the size of the holes to be formed, but is preferably 20 ° C. or lower. The lower the temperature of the jig, the better. If the temperature is too low, there is a problem that water droplets are condensed on the periphery and workability is deteriorated, and the time required for drilling is long. In consideration of these, it is preferable to keep the temperature at 5 ° C. or higher. A particularly preferred temperature range is
10-20 ° C.

The perforation of the film sheet can be performed batchwise, but it is efficient to perform the perforation continuously. The film sheet is sent out from one side, and the film sheet is guided to a laser processing site via a balancer. When the film sheet reaches the laser processing station, the movement of the film sheet in the laser processing station is temporarily stopped, and a laser beam is applied to the film sheet in combination with a mirror to make a hole of a predetermined size in a predetermined shape. When the holes have been made, the stopped film sheet is moved. When the position where a hole is to be made next to the film sheet reaches the laser processing station, the movement of the film sheet is similarly stopped, and a predetermined position is irradiated with a laser beam to the film sheet to make a predetermined hole in the film sheet. After piercing, the film sheet is moved.
The same operation is continuously performed. The perforated film sheet is sequentially wound up. The feeding and winding of the film sheet is processed continuously. Since the drilling process using laser light is a batch operation, the balance between the continuous operation and the batch operation is adjusted by a balancer. The shape of the hole can take various shapes such as a square, a triangle, a polygon, a circle and an ellipse. Generally, a circle is preferred.

For drilling, various laser beams can be used. Gas lasers such as a He-Ne laser, an argon laser, a carbon dioxide gas laser, and an excimer laser, and solid lasers such as a ruby laser, an Nd-YAG laser, and an Nd-glass laser can be used. Among them, a carbon dioxide gas laser can be used easily and conveniently.

[0018]

Next, the present invention will be described with reference to embodiments. FIG. 3 shows an example of a method for making small holes in a film sheet. A polyamide film sheet is fed out from a roll of polyamide film sheet 32 having a thickness of 25 μ via a supply roller 33. The polyamide film sheet reaches the laser processing station 40 via the balancers 34 and 38. In the laser processing station 40, two holes having a diameter of 6 mm are formed in the polyamide film sheet by the laser beam 44 per unit package. At this time, the laser beam oscillated from the laser oscillator 35 is reflected by the mirrors 42 and 43 and irradiated on the film sheet. By operating the mirrors 42 and 43, holes of a predetermined size are formed on the film sheet in a predetermined shape. The light-perforated film sheet is wound up as a sheet roll 37 through balancers 36 and 39.

The speed of the film sheet to be delivered depends on the dimensions of the packaging material for cooking food and drink, the output of the laser oscillator, and the like. Assuming a bag-shaped packaging material having a size of 180 mm × 120 mm, when a carbon dioxide laser oscillator having an output of 30 W is used, the time required for punching is 1.9 seconds, and the sending speed of the film sheet is 6 m / m. Minutes. The polyamide film sheet delivered from the sheet roll 32 has the dimensions of the packaging material, here, every 180 mm,
A hole is drilled. When the holes are made, the running of the film sheet is temporarily stopped. When the holes are formed, the film sheet is moved by 180 mm, temporarily stopped, and laser light is oscillated to make holes in the film sheet. After drilling,
A hole is made by running the film sheet 180 mm. These operations are repeated to make holes in the film sheet. Delivery of the film sheet is performed continuously,
Since the drilling is performed batchwise, adjustment during that time is performed by the balancers 34, 36, 38, and 39. The perforated film sheet is wound up in this example, but may be supplied directly to the next step, for example, a lamination step, without winding up.

FIG. 2 shows a portion where a film sheet is irradiated with a laser beam. A small hole 2 is made in the film sheet 1. The laser beam is irradiated from above in the figure (not shown). The non-irradiated side of the film sheet with laser light,
That is, a jig 4 for sucking a small piece generated when making a small hole is provided below the figure. The jig 4 is provided with a suction hole 6 having a diameter larger than the diameter of the hole to be drilled.

In FIG. 2, the film sheet 1 advances to the left in the figure. A jig 4 is provided near a position where the hole 2 of the film sheet 1 is to be formed. The film sheet is in direct contact with the jig centering on the contact portion 5 which is the tip of the hole to be drilled. The suction hole of the jig is set to be larger than the diameter of the hole to be formed in the film sheet. The contact portion 5 which is the tip of the hole 2 to be drilled in the film sheet 1 is in direct contact with the jig 4. In this state, the film sheet is irradiated with laser light to make holes in the film sheet.

The laser beam is focused and applied to a target position. The position where the laser beam is first irradiated is the contact portion 5 which is in contact with the jig 4. Thereafter, the laser beam is irradiated while moving the laser beam along the contour of the hole to be drilled. When the laser beam is irradiated along a predetermined contour, the portion irradiated with the laser beam is cut, resulting in a hole. The film sheet corresponding to the hole portion becomes a small piece and is sucked through the suction hole 6.

In FIG. 2, by contacting a contact portion 5 which is a part of a small hole to be drilled with the surface of the jig 4,
This makes it possible to make beautiful holes in the film sheet that are uniform in shape and have no swelling in the openings. The jig is preferably cooled by passing cold water through the jig. The temperature of the jig is appropriately set according to the thickness of the film sheet and the size of the hole to be formed. The temperature of the jig can be set by changing the temperature of a cooling medium passing through the jig, for example, water.

The small holes can be made by a set of laser light irradiators as shown in FIG. 2, but are not limited to this. A plurality of small holes can be simultaneously drilled using a plurality of laser light irradiators. 2 sets of laser light irradiators
FIG. 4 shows an example in which individual small holes are formed.

FIG. 5 is an enlarged view of the vicinity of the small hole. The film sheet in the small holes 2 shrinks due to heat to form small pieces 7. The small pieces 7 are sucked and removed from the suction holes 6 of the jig 4. As described above, when the film sheet is irradiated with the laser beam without being brought into contact with the jig, the contracted small pieces 7 tend to be fused to the film sheet 1 and cannot be removed from the suction holes.

A film sheet provided with small holes as described above, for example, a nylon film sheet having a thickness of 25 μm and having two holes having a diameter of 6 mm is laminated with a polyethylene film sheet. On the other hand, a food and drink package can be obtained by manufacturing a tray from a two-layer film sheet in which polyethylene is laminated on polypropylene, putting food and drink in the tray portion, and further covering the laminate film sheet thereon. This food and drink package can be easily cooked in a microwave oven.

[0027]

According to the present invention, there is provided a method for forming small holes by subjecting a film sheet used for a food or beverage package to laser light treatment. There is no swelling around the hole, making it possible to make a beautifully aligned hole. Since there is no bulge around the hole of the film sheet, even when the film sheet is wound up, there is no swollen portion, and there is no hindrance to the work in the subsequent process.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a case where laser light irradiation is performed. (A) is a side view, (b) is a plan view.

FIG. 2 is a diagram illustrating a laser beam irradiation part.
(A) is a side view, (b) is a plan view.

FIG. 3 is a diagram illustrating an example of a step of making small holes in a film sheet.

FIG. 4 is a diagram showing a laser beam irradiation portion when two small holes are made. (A) is a side view, (b) is a plan view.

FIG. 5 is an enlarged view of the vicinity of a small hole.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Film sheet 2 Small hole 3 Rise 4 Jig 5 Contact part 6 Suction hole 7 Small piece 32, 37 Sheet scroll 33, 41 Roller 34, 38, 36, 39 Balancer 35 Laser light oscillator 40 Laser processing place 42, 43 Mirror (reflection Mirror) 44 laser beam 71 film sheet 72, 73 small hole 74, 75 suction hole 76, 77 jig 78, 79 contact part

Claims (3)

[Claims] When a small hole is made in a film sheet by laser light treatment, a part of a part of the film sheet to be made hole is cut off by laser light irradiation on a non-laser light irradiation side of the film sheet. A method for perforating a film sheet, comprising irradiating a laser beam onto the film sheet while directly contacting a surface of a jig having holes for sucking small pieces. 2. A film sheet is irradiated with a laser beam on a portion of the film sheet which is in direct contact with the surface of the jig. The laser beam is irradiated while moving the laser beam along the contour of a hole to be drilled from that position. The method according to claim 1, wherein holes are formed in the sheet. 3. The method for perforating a film sheet according to claim 1, wherein the temperature of the jig is set to 30 ° C. or lower.