JPS6026693B2 - Method for manufacturing bending film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a bendable film, and more specifically, a method for producing a film having a structure in which box-like protrusions of uniform depth are arranged without gaps.

The term "film" as used herein includes a sheet having a thickness of about 1 liter. Films having a large number of box-like protrusions of uniform depth are widely used as materials for packaging containers and sweetfish seasoning films.

Among them, the box-like protrusions are lined up without gaps. When a bent film with a similar structure is used in a laminated film, it becomes an excellent heat-retaining sheet, so it is expected to have a wide range of uses.
Flexible films, which consist of a large number of box-like protrusions of uniform depth, are usually made of thermoplastic resin. This film can also be made by passing a flat film between a pair of rolls and embossing the roll surface, but this method does not allow the box-like protrusions to be lined up without gaps. Further, this bent film can also be made by air pressure forming or suction forming, but even with this method, it is not easy to form a structure in which the protrusions are lined up without gaps. This inventor applied air pressure molding and suction molding,
Therefore, without using a mold that restricts the outer shape of the box-like protrusion,
Instead, we devised a method to obtain a film with a structure in which a large number of box-like protrusions of uniform depth are lined up without gaps by using a net-like material.

The gist of this invention is to use a mesh material instead of a mold to produce a bendable film by air pressure molding, suction molding, or a combination of these methods. This invention involves placing heat-softened thermoplastic resin films on a perforated plate in parallel so as to overlap them, moving them in the same direction at a constant speed, protruding the film toward the perforated plate, and forming the film. In this method, a silk-like material is inserted between the film and the perforated plate, the net-like material is kept under tension and placed parallel to the perforated plate, the mesh-like material is advanced together with the film, and compressed air is applied from the top surface of the film. The film inside the mesh is made to protrude and the protruding end of the film is brought into close contact with the perforated plate by applying suction or suction from the bottom surface, or by using a combination of these. The present invention relates to a method for manufacturing a flexible film, which is characterized in that the film is formed in close contact with each other.

The method of this invention will be explained as follows based on the drawings.

FIG. 1 is a partially cutaway sectional view schematically showing the method of this invention. In FIG. 1, 1 is a thermoplastic resin film, 2 is a perforated plate, 3 is a roll that advances the perforated plate 2, 4 is a vacuum suction chamber, and 5 is a heater. , 6 are on both sides of the perforated plate 2, and the perforated plate 2
This is a tenter that moves at the same speed in the same direction as the tenter. The tenter 6 is provided with clamps 7 intermittently. 8 is a silk-like material, which is held between clamps 7 and advanced by a tenter 6. The silk material 8 is stretched out in one plane by the tenter 6 and maintained under tension without any sagging. In addition, the net-like material 8 is a perforated plate 2
The perforated plate 2 is located a certain distance away from the
is held parallel to. The film 1 is folded over the mesh 8 and is advanced in the direction of the arrow at the same speed as the perforated plate 2, and therefore also in the same direction as the mesh 8.

In the meantime, the film 1 is heated by the heater 5, softened, and advances into contact with the silk material 8. As the film, it is possible to use a film that has just been extruded by an extruder and has not yet been cooled.
In this way, when the softened film 1 and the net-like material 8 are overlapped and placed above the suction chamber 4, the air between the film and the perforated plate 2 is sucked, and the film 1 is attracted to the perforated plate 2. At this time, the silk material 8 is maintained under tension by the tenter 6 and is located parallel to and spaced apart from the perforated plate 2 by a certain distance.

Therefore, the part of the film that is in contact with the vertical object 8 is
It is locked by the mesh 8. However, the portions of the film 1 between the meshes of the silk 8 are stretched and protrude toward the perforated plate 2. The protruding tip is brought into close contact with the perforated plate 2. Therefore, a box-shaped protrusion is formed between the mesh and the perforated plate. Further, the portion of the film 1 located at the silk material 8 is folded back by the mesh material 8, and the film 1' in the vicinity thereof hangs down from the mesh material 8, forming a double wall. The height of the side walls of the box-shaped protrusion is equal to the distance between the mesh 8 and the perforated plate 2. The protruding film 1 is formed of a large number of closely spaced box-like protrusions of uniform depth, and most of the side walls are fused together. When the film formed as described above is cooled as it is, a bent film having a structure in which a large number of box-shaped protrusions of uniform depth are provided closely to each other is obtained.

In the bent film thus obtained, the portion corresponding to the closing portion of the box-like projection is folded back, and the mesh material 8 is integrally enclosed inside the folded portion. Therefore, the bending film is reinforced by the net-like material 8, and a strong bending film is obtained. This flexible film can thus be used as a rigid packaging container suitable for storing various items within the box-like projection.

Further, this bending film can be made into a two-layer sheet over the entirety by pasting another film on the opening. This sheet can be used as a heat retention sheet. The method of this invention has the advantage that such versatile flexible films can be easily and continuously produced. This invention method is an improvement on conventional pressure molding and suction molding.

In conventional air pressure molding and suction molding, the silk material 8 is not used, but a mold is used instead. The mold specifies the shape to be molded and is either placed directly on the perforated plate 2 or made integrally with the perforated plate 2. Further, in the continuous suction molding method, the thermoplastic resin film 1 is held between the clamps 7 of the tenter 6, is advanced together with the tenter 6, and is suctioned into a mold above the suction chamber 4 to perform molding. In contrast, the method of this invention does not use a mold, but instead uses a mesh 8.

Moreover, the net-like material 8 is placed at a distance from the perforated plate 2, and for this purpose, the silk-like material 8 is held between the clamps 7 of the tenter 6 and moved together with the perforated plate 2. Also,
During molding, a part of the film 1 is locked onto the silk-like material 8, and the remaining film is made to protrude from between the meshes of the net-like material 8 toward the perforated plate, and only the tip is placed on the perforated plate. The box-shaped protrusions are formed without any gaps, and the side walls of each protrusion are in close contact with each other. In these respects, the method of the present invention differs from the conventional suction molding method. Various thermoplastic resin films can be used as the film in this invention.

Among them, ethylene resins, vinyl chloride resins, and styrene resins are most suitable. Film thickness is 0.0
The material is not limited to a sheet as thin as 0.2 or 0.1 willow, but may be as thick as approximately 1 side, which is called a general sheet, as mentioned earlier. The net-like material in this invention is not only the binding net of the present pot, but also is formed by intersecting a large number of filamentous materials, and as a result, gaps are formed between the meshes through which the film can protrude. If there is, it can be anything.

The intersections of the filaments do not necessarily need to be fixed. In addition to natural fibers and synthetic fibers, filamentous materials include
Various materials such as synthetic resin fibers, glass fibers, metal wires, etc. can be used. As natural fibers, in addition to cotton and silk, recycled fibers such as rayon and cupro can be used. Further, as the synthetic fiber, polyester, polyamide, polyacrylonitrile, etc. can be used. Furthermore, a polyethylene film made into silk by making cuts can also be used as a net-like material. Further, the shape of the mesh is not limited to a quadrangle, but may be a triangle or a polygon of pentagon or more. Also,
The mesh size is preferably 3 to 30 ribs in diameter, particularly preferably 5 to 15 ribs, if expressed as the diameter of a circle with the same area. When synthetic fibers are used as the net-like material, it is desirable that the silk-like material be made of a material having a softening point higher than that of the film. Further, in the above description, an example was shown in which the suction chamber 4 is provided and vacuum suction is performed to provide the protrusions on the film 1, but the provision of the protrusions is not limited to this example. For example, the projections can be provided by applying pressurized air from above the film, or by using both suction and pressurized air to press the film 1 toward the perforated plate 2. The depth of the protrusions is 2 mm, 2 mm, preferably 3 mm, 6 mm.
The inventive method described above gives good results when the silk material 8 is relatively narrow and has low elongation under tension.

However, when the silk material 8 becomes wide, the tenter 6
If only both sides are supported, the net-like material 8 will sag in some places, making it difficult to maintain the net-like material 8 in a tensioned state, and therefore making it difficult to maintain the mesh-like material 8 parallel to the perforated plate 2. Therefore, the second invention is an improvement on this point. The gist of the second invention is that a special partition plate is provided between the mesh material 8 and the perforated plate 2 in the first invention described above.

That is, the gist is to slide the net-like material 8 along the upper surface of the side slope and prevent the net-like material 8 from sagging using the partition plate. Further, in the second invention, the tip of the partition plate is positioned above the suction chamber 4, and the partition plate above the suction chamber 4 is cut out at some places to provide unevenness on the partition plate, and the defective recesses are formed. The main idea is to first make the film partially protrude, and then make the remaining part of the film protrude away from the diaphragm, thus making the film protrude in stages. In the second invention, a heat-softened thermoplastic resin film is placed in parallel with a perforated plate so as to overlap, and these are advanced in the same direction at a constant speed so that the film protrudes toward the perforated plate. In the method of forming, a partition plate with many irregularities on one side is inserted between the film and the perforated plate, a net-like material is inserted between the film and the partition plate, and the net-like material is inserted into the partition plate. First, pressurized air is applied from the top surface of the film in the recessed part of the partition plate, or suction is applied from the bottom surface of the film, or by using a combination of these, the film inside the mesh is made to protrude and the protruding ends are inserted into the holes. Place it in close contact with the perforated board,
After that, after leaving the convex part of the partition plate, pressurized air is applied from the top surface of the film, suction is applied from the bottom surface, or a combination of these is used to cause the remaining film within the mesh to protrude by air force, and the protruding end This invention relates to a method for manufacturing a bending film, characterized in that the film is brought into close contact with a perforated plate, and box-shaped protrusions of uniform depth are formed in many stages in close contact with each other.

The second invention will be explained as follows based on the drawings.

FIG. 2 is a partially cutaway sectional view similar to FIG. 1 schematically showing the method of the second invention. In Figure 2, 1 is absent,
8 is the same as that shown in FIG. Figure 2 is the first
The main difference from the figure is that a special partition plate 9 is inserted between the silk material 8 and the perforated plate 2. Partition plate 9
is fixed in front of the suction chamber 4, with the tip 10 extending into the suction chamber 4. FIG. 3 is an enlarged perspective view of a part of FIG. 2.

In Fig. 3, a perforated plate 2 and a thermoplastic resin film 1 are shown.
is made to proceed at a constant speed in the direction of arrow a. A net-like material 8 is positioned below the film 1, and the net-like material 8 is held between the clamps 7 of the tenter 6 and is advanced in the direction of arrow a at the same speed as the film 1. The silk material 8 is maintained under tension by the tenter 6. A partition plate 9 is provided below the net-like material 8, and the corner plate 9 has its tip 10 located in the center of the suction chamber 4 and is fixed in this state.
Therefore, above the suction chamber 4, the mesh 8 is initially exposed to the partition plate 9.
It will slide on the top surface of the. The partition plate 9 will be explained in more detail as follows.

The partition plate 9 has a generally flat plate shape, on which the silk-like material 8 is slid, and serves to maintain the net-like material 8 parallel to the perforated plate 2. The partition plate 9 is provided with unevenness along the tip 10, and the protrusion forms a protrusion 11 that protrudes in the direction of arrow a. In other words, a pincer-shaped recess 12 is provided on the side of the tip 10 facing in the opposite direction to the arrow a. Moreover, the protrusion 11 and the depression 12 are located directly above the suction chamber 4, and the bottom of the depression 12 has a structure on which the perforated plate 2 slides. The film 1 placed on the partition plate 9 has already been heated and softened. Therefore, when the film 1 is placed over the recess 12 provided in the partition plate 9, the film 1 is sucked by the suction chamber, and only the portion corresponding to the recess 12 is made to protrude. At this time, since the net-like material 8 is stretched over the recess 12, the film 1 is locked at the mesh-like material 8. Therefore, only the film 1 between the meshes protrudes to form a box-like protrusion. Since the recess 12 gradually becomes wider as it progresses in the direction of the arrow a, the proportion of the protruding portion of the film 1 gradually increases as it progresses in the direction of the arrow a. thus,
When leaving the tip 10 of the diaphragm 9, a box-like protrusion will be formed over the entire width of the film 1. Partition plate 9
As mentioned above, the film 1 is first removed at the tip of the recess 12.
is partially protruded to form a box-like protrusion.

At this time, since the silk-like material 8 is partially supported by the base of the protrusion 11, it does not sag in the width direction. For this reason,
The protruding height of the film 1 can be reliably made uniform. In other words, the protruding height of the film is set to a length equal to the thickness of the corner plate 9,
You can definitely arrange it. Moreover, since the width of the recess 12 was gradually widened earlier, the protrusion of the film 1 gradually widens in the width direction as it progresses. Since the spread is gradual, it is natural to form a protrusion. Also,
During the protrusion formation, the silk 8 is always held at least slightly by the diaphragm 9 at the midpoint in the width direction, so that the mesh 8 is always kept parallel to the perforated plate 2. Therefore, the height of the protrusion formed between the net-like material 8 and the perforated plate 2 is uniform throughout. Thus, according to this method, it is possible to easily produce a uniformly bent film over a wide width. Although FIG. 3 shows an example in which the partition plate 9 is provided with a sliding door-shaped recess and a protrusion at its tip, the unevenness is not limited to this.

The unevenness may consist of depressions and protrusions in the shape of a right-angled quadrilateral in a horizontal cross section. It is desirable that the width of the unevenness is larger than the width of the mesh. In addition, in Figures 2 and 3,
Although an example has been shown in which suction is performed using the suction chamber 4, the film 1 may be made to protrude by applying pressurized air from above the film.

[Brief explanation of the drawing]

FIG. 1 is a cutaway sectional view schematically showing one embodiment of the present invention. FIG. 2 schematically shows another embodiment of the invention.
It is a cutaway sectional view. FIG. 3 is an enlarged perspective view of a part of FIG. 2. In the figure, 1 is a thermoplastic resin film, 2 is a perforated plate, 3 is a roll for advancing the perforated plate 2, 4 is a vacuum suction chamber, 5 is a heater, 6 is a tenter, 7 is a clamp, and 8 is a In the net-like material, 9 is a partition plate, 10 is a tip of the partition plate, 11 is a protrusion of the partition plate 9, and 12 is a depression in the partition plate 9. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Films of heat-softened thermoplastic thermoplastic resin are placed in parallel to a perforated plate so as to overlap, and the films are advanced in the same direction at a constant speed to project the film toward the perforated plate. , a method for forming a film, in which a net-like material is inserted between the film and a perforated plate, the net-like material is maintained in a tensioned state and placed parallel to the perforated plate, the net-like material is advanced together with the film, and the film is formed. By applying compressed air from the top surface, by suction from the bottom surface, or by using a combination of these, the film is made to protrude and the protruding end of the film is brought into close contact with the perforated plate, thereby forming a large number of box-like protrusions of uniform depth to each other. A method for producing a bent film, characterized by forming the film in close contact with each other. 2. A method of forming a film by placing a heat-softened thermoplastic resin film in parallel with a perforated plate and moving them in the same direction at a constant speed to project the film toward the perforated plate. In this method, a diaphragm with many irregularities on one side edge is inserted between the film and the perforated plate, a net-like material is inserted between the film and the diaphragm, and the net-like material is placed along the surface of the diaphragm. First, pressurized air is applied from the top surface of the film in the recessed part of the partition plate, or suction is applied from the bottom surface, or by using a combination of these, the film in the mesh is made to protrude, and the protruding end of the film is inserted into the perforated plate. After that, when the film leaves the convex part of the partition plate, compressed air is applied from the top surface of the film, or suction is applied from the bottom surface, or by using a combination of these, the remaining film inside the mesh is protruded and the film is removed. A method for producing a bent film, characterized in that the protruding end is brought into close contact with a perforated plate, thereby forming a number of box-like protrusions of uniform depth in close contact with each other in stages.