JPS6058013B2 - Method for manufacturing mesh-reinforced bending film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a flexible film reinforced with a mesh.

The term "film" here includes sheets having a thickness of 1 Tfgn or more. Films with a large number of box-like projections of uniform depth are widely used as packaging containers and as materials for laminated films. Among them, the bending film has a structure in which box-like protrusions are lined up without gaps.
When used in laminated films, it becomes an excellent heat-retaining sheet, so it is expected to have a wide range of uses. A bent film with a structure in which a large number of box-like protrusions of uniform depth are lined up is produced by passing a thermoplastic resin film between a pair of embossing rolls, or applying pressure or suction onto a perforated mold. This can be made by molding.

However, by these methods, it is not possible to obtain a bent film having a structure in which the protrusions are arranged without gaps. The inventor previously proposed a convenient method for producing a bent film with a structure in which box-like protrusions of uniform depth are lined up without gaps.

This method does not use the above-mentioned embossing roll or perforated die, but instead uses a net-like material. Specifically, a net is placed above a flat perforated plate, the net is kept parallel to the perforated plate in a tensioned state, and a thermoplastic resin film is placed on top of the net. The film is heated and softened, and pressurized or reduced pressure air is applied to the film to bring the film into close contact with the perforated plate, causing the film located within the mesh of the mesh to protrude in a box-like manner. The film is folded back twice to create a bent film with a structure in which the side walls of the box-like object are connected in a net-like manner. According to this method, a bent film having a structure in which box-like protrusions are consecutively arranged without gaps can be obtained. This film has a structure that includes a mesh material, so it can be seen as a flexible film reinforced with a mesh material. According to the above-described method, even if the net-like material has some degree of elasticity, it is possible to easily produce a bent film having a relatively small area. However, it is difficult to obtain a flexible film with a large area. This is because, in the case of large-area products, the suction or pressure during molding causes the net-like material, especially the elastic net-like material, such as plastic net, to be displaced together with the heat-softened film, and the box-like protrusions near the fulcrums at both ends are displaced. This is because, although the desired depth is obtained, the depth of the box-shaped protrusion at a portion far from the fulcrum is shallow. In order to hold the elastic wide net-like material parallel to the perforated plate during molding, the inventor installed a support in the form of a base grid at a constant height between the net-like material and the perforated plate. I thought of inserting it.

The inventor decided to construct a base mesh-like support with a large number of strips, and the strips were made of a thin, strong material with equal width and thickness, and the widths were oriented vertically and the longitudinal direction was arranged vertically and horizontally. We decided to intersect them and configure them in the shape of a base pattern. Then, this support is placed on a perforated plate, the mesh is placed under tension on the support, and a polyethylene film that has been softened by heat is placed on top of it to absorb air from under the perforated plate. Then vacuum forming was performed. In this way, the ends of the net and the support were folded back, and the side walls were fused together to form an adjacent box-shaped continuous body. Thereafter, the perforated plate was first removed from the box-like continuous body, and then the support was removed, and a box-like continuous body in which the film and the net-like material were integrated was obtained. The inventor confirmed that the resulting box-like connected body was supported by a support, and thus became a box-like body in which all the side walls had substantially uniform heights. Further, the inventor has confirmed that this box-shaped continuous body can be easily separated from the support. This invention was made based on such confirmation. This invention arranges a large number of strips of equal width,
The width direction is upright and the longitudinal direction is crossed vertically and horizontally to form a support in the form of a base mesh, and the support is placed on a perforated plate, and a net-like material is placed on the support to create a tensioned state. A heat-softened thermoplastic resin film is placed on top of the net and maintained under tension, and pressurized air is applied from the top of the film, suction is applied from the bottom, or a combination of these is applied. The film is plunged into the gap between the mesh of the net and the support, the plunge end is brought into close contact with the perforated plate, and the film is formed into a number of box-like connected bodies, and the film is inserted into the support and the perforated plate together with the net. The present invention relates to a method for producing a flexible film reinforced with a mesh material, characterized in that it is separated from a plate.

The method of this invention will be explained with reference to the drawings as follows.

FIG. 1 is a vertical cross-sectional view schematically showing a method for manufacturing a flexible film according to the present invention. FIG. 2 is a partially cutaway perspective view of the process of manufacturing a bendable film according to the present invention. FIG. 3 is a partially cutaway perspective view of a bendable film obtained by the inventor. FIG. 4 is a partially cutaway exploded perspective view of the support used in the present invention.
In FIG. 1, reference numeral 1 denotes a band-shaped body, and the band-shaped body 1 has its width upright and its longitudinal direction intersecting both vertically and horizontally, thereby forming a base-like support.

The support is placed on the perforated plate 2. 3 is a net-like material, and the net-like material 3 is placed on a support and maintained under tension.

4 is a thermoplastic resin film, and the film 4 is placed on the mesh 3 and maintained under tension.

The space between the film 4 and the perforated plate 2 is closed by a frame 5,
Maintained airtight. 7 is a decompression chamber, and 8 is an air suction port.

As shown in FIG. 1, a support consisting of a strip 1 and a net 3 are placed on a perforated plate 2, and a film 4 that has been softened by heating is placed on top of the support at another location.

Next, air is removed from the suction port 8, and the pressure inside the decompression chamber 7 is reduced. Then, the film 4 plunges into the mesh of the net-like material 3 and the base meshes or gaps of the support, and the tip of the film that plunges in comes into close contact with the perforated plate 2. As a result, the film 4 is formed into a box-like projection with the perforated plate 2 at the bottom within the mesh and the gaps. At this time, the part of the film 4 in contact with the net-like material 3 is folded back along the net-like material 3 and hangs down to surround the net-like material 3, and the hanging portions are closely placed back to back to form a double wall. Further, the portion of the film 4 that is in contact with the strip 1 is bent along the strip 1,
This constitutes a narrow groove in which the strip 1 is accommodated. The height of the side wall of the box-like projection is equal to the width of the strip 1. In this way, the protruding film 4 becomes a series of box-like protrusions of substantially uniform depth. The state at this time is shown in FIG.

FIG. 2 shows the state in which the lower part is formed into a series of box-like protrusions, and the upper part shows the state before that. Figure 2 1
The two box-like bodies 9 are connected to adjacent box-like bodies 10 with the tips of their side walls folded back. A net-like material 3 is enclosed in the folded portion. Where the mesh 3 is enclosed, the side walls of the adjacent box-like bodies 9 and 10 are in close contact with each other, with almost no gap between them, forming a double wall. are doing. However, since the strip 1 is present where the box 9 contacts the adjacent box 11, the film is bent along the strip 1 to form a narrow groove with the strip 1 sandwiched therebetween. Become. After forming into a box-like continuous body in this manner, the decompression chamber 7 is opened, and then the film 4 is cooled.

Thereafter, when the film 4 is pulled away from the perforated plate 2, the film 4 is taken out while containing the support made of the strip 1 and the net-like material 3. The box-like connected body thus taken out has the bottom edge exposed at the end of the support made of the band-like body 1. When the support is removed from the exposed surface, the film 4 is obtained as a series of box-like protrusions in which the net-like material 3 is enclosed. This series of box-shaped protrusions is the bent film that is the object of the method of this invention. The bent film thus obtained is shown in FIG.

In FIG. 3, between two adjacent box-like bodies 9 and 10, the side walls of each box-like body form a double wall that is in close contact with each other.
A mesh material 3 is enclosed in the folded portion of the double wall. However, between two adjacent box-shaped bodies 9 and 11, the side walls of each box-shaped body are folded back leaving a small gap to form a narrow groove 12, and the groove is formed by the bottom of the box-shaped body. It is open. This box-like connected body has a structure in which each box-like body is closely formed with no gaps except for the portion where the groove 12 is formed. The bending film thus obtained has a stable shape and is strong because the mesh material 3 is enclosed in the folded portion of the double wall, and the mesh material 3 acts as a reinforcing body.

Furthermore, since this bending film has box-like bodies arranged one after another with almost no gaps, it is possible to distinguish between items in each box-like body, and it is also possible to put the largest amount of objects in the most efficient manner. can. Therefore, this flexible film can be used for packaging articles. In addition, a film is attached to the opening of the bent film box to form independent air bubbles in the box, which can be used as a heat insulating material and a cushioning material. Therefore, this bent film formed into a box-like continuous body is useful. In the above explanation, one embodiment of the method of the present invention has been described using the vacuum forming method as an example, but the method can be said to be an improvement on the conventional vacuum forming method. The mesh 3 in the invention has not been used, instead a mold has been used.

The mold has the shape to be molded and is either placed directly on the perforated plate 2 or made integrally with the perforated plate 2. However, the above-mentioned method of the invention does not use a mold, but uses a mesh 3 instead. Moreover, the net-like material 3 is placed at a distance from the perforated plate 2 and parallel to the perforated plate 2. For this purpose, a support made of a strip 1 is used, which is interposed between the perforated plate 2 and the mesh 3 to ensure the maintenance of the spacing between them and the parallel relationship between them. There is. Moreover, by placing this support on the perforated plate 2, the lower end of the support can be removed from the molded body. In this respect, the method of the present invention differs from conventional molding methods. The main points of the inventive method have been explained above regarding one embodiment of the inventive method.
Below, detailed matters regarding the method of this invention will be explained for each requirement.

An example of the support is shown in FIG.

The support is made into a grid pattern by combining a large number of strips 1 of the same width. Each of the strips 1 has its width direction perpendicularly oriented and its longitudinal direction parallel to each other. At the intersection of the vertically oriented strip and the horizontally oriented strip, a notch 13 extending in the width direction is provided from the end to the center of the width, making it convenient to combine them in a cross shape. As a result, in the support, the upper edge and the lower edge of each strip-shaped body 1 are on the same plane, and the plane connecting the upper edges and the plane connecting the lower edges are parallel to each other. Therefore, when this support is placed on the perforated plate 2, the lower edge of each strip 1 comes into close contact with the perforated plate 2, and the surface connecting the upper edge of each strip is the same as that of the perforated plate. It becomes a plane parallel to 2. The distance between the strips 1 in the support material, ie, the size of the base mesh, is made larger than the distance between the meshes in the mesh material 3, and is usually several times larger.

The distance should be as large as possible within a range that does not cause the net-like material placed on top of it to bend significantly. Moreover, the band-shaped body 1 is
If possible, make this from a heat-resistant material and make it as thin as possible. In addition, a mold release agent is applied to the surface of the strip 1,
The formed film becomes easier to separate from the strip 1. The support does not require that the base lines formed between the strips be rectangular.

The base-like gaps may be triangular, pentagonal, or circular.
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. The thickness of the film is 0
．． The material is not limited to a thin material of about 0.02 to 0.1 wn, but as mentioned earlier, it may be a thick material of about 17 m or more, which is generally called a sheet. The net-like material according to the present invention includes not only a net formed by tying threads together, but also any material formed by intersecting a large number of thread-like materials. That is, this net-like material may be of any kind as long as it has a mesh with gaps that allow the film to protrude from the mesh. The intersection of the threads does not necessarily need to be fixed. The threads include natural fibers, synthetic fibers, synthetic wood fibers,
Various materials such as glass fiber and metal wire can be used. As natural fibers, in addition to cotton and silk, recycled fibers such as rayon and Kyupura can be used. Further, as the synthetic fiber, polyester, polyamide, polyacrylonitrile, etc. can be used. Also, medium and low pressure poly. A net made by making cuts in an ethylene film, a rotating die extrusion net, etc. can be used as the net. 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, if the size of the mesh is expressed as the diameter of a circle with the same area, the diameter is 3 to 30rrn.
It is preferable to have a size of 5 to 15 wn.
Particularly preferred. When synthetic fibers (including plastic nets) are used, the netting is a material with a softening point higher than that of the film, preferably 10
It is made of a material with a softening point as high as ℃ or higher. In the above explanation, an example was shown in which vacuum forming is performed by providing a decompression chamber 7 and sucking air in order to form the film 4 into a series of box-shaped protrusions, but the attachment of protrusions is not limited to this. .

For example, pressurized air may be applied from above the film 4, or a combination of vacuum and pressure may be used. The depth of the protrusion is 2 to 10 rfr! Ill preferably 3 to 6T
It is n. However, if it is used for packaging, it may be larger than this. It is desirable to apply a mold release agent to the surface of the perforated plate 2 in order to facilitate the separation of the molded box-like projections. As described above, the bendable film obtained according to the present invention has a large number of box-like protrusions of uniform depth and is reinforced by the mesh, making it extremely durable.

Therefore, it can be used as a packaging container with a large number of storage spaces, and by applying a film thereto, a heat insulating sheet having a large number of closed cells can be obtained.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view schematically showing a method for manufacturing a flexible film according to the present invention.

Claims (1)

[Claims] 1 A large number of strips of equal width are arranged, their width directions are upright, and their longitudinal directions are crossed vertically and horizontally to form a support in the shape of a base mesh, and the support is placed on a perforated plate. A net-like material is placed on a support and maintained in a tensioned state, a heat-softened thermoplastic resin film is placed on the mesh-like material and maintained in a tensioned state, and pressurized air is applied from the top surface of the film or from the bottom surface. Using suction or a combination of these, the film is plunged into the mesh of the mesh and the base mesh of the support, and the plunge end is brought into close contact with the perforated plate to form the film into a number of box-like continuous bodies. A method for producing a flexible film reinforced with a mesh, characterized in that the film is separated from a support and a perforated plate together with the mesh.