JP2005035071A - End closing treatment method of plastic cellular board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for closing the opened end of a plastic cellular board, which is obtained by pasting up a flat back sheet and a flat liner sheet on the bottom and top surfaces of the caps of a cap sheet having a large number of cap-like projections obtained by molding a plastic sheet extruded in a molten state, using a simple technique and an apparatus comprising common constituent parts. <P>SOLUTION: The end of the cellular board is heated by the irradiation with heat rays using an infrared heater (4) to soften the walls of the caps exposed to the end, the walls (31) of the caps arranged in the vicinity of the end, the edge (11) of the back sheet and the edge (21) of the liner sheet, and the softened edges (11) and (21) of both of the back sheet and the linear sheet are bonded under pressure by a press bonding stand (5) and a press bonding press (6) to close the end of the cellular board. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for closing an open end face of a plastic foam board.
[0002]
[Prior art]
A plastic, typically polypropylene, is melt extruded from a T-die, and the sheet is usually formed into a cap sheet having a large number of cap-shaped protrusions by vacuum forming, and is flat on the bottom and top surfaces of the cap. A plastic foam board (hereinafter abbreviated as "bubble board") made by fusing the back sheet and liner sheet into a hollow plate is manufactured, and its light weight and rigidity are bought for various applications. in use.
[0003]
An important application of the foam board is the manufacture of a container for packaging or transportation, but depending on the use of the container, it is often difficult to have a structure in which the end face of the foam board is open. For example, a fresh fish container to be washed with water is an example, and not only fresh fish but generally a food container must prevent water and dust from entering the bubble board from the open end face.
[0004]
Therefore, various techniques for closing the end face of the bubble board have been devised, and some of them have been put into practical use. The applicant has also developed and disclosed a method for treating the edges of plastic corrugated cardboard (a generic term for rigid plastic hollow plates, including bubble boards in which the corrugated paper structure is made of plastic material). (Japanese Patent Laid-Open No. 2003-62917). There are two types of edge treatment methods: an embodiment using a plastic dressing band and an embodiment not using a plastic dressing band.
[0005]
The mode of using the decorative band is that the edge of the plastic corrugated cardboard and the outside thereof are regulated from both sides with a pressing plate, and a plastic decorative band having a width equal to the thickness of the plastic corrugated cardboard is applied to the edge, and from the outside It consists of applying a metal backing plate and heating it with a heater from behind through the backing plate to fuse the decorative band to the edge. A mode in which a decorative band is not used is a metal having a U-shaped cross section and a cross section of a portion that transitions from both sides to a bottom surface while being curved with a pressing plate from both sides, leaving at least a certain width near the edge of the plastic cardboard. A plastic jig near the edge is softened and melted and deformed along a curved surface by applying a jig made to the edge and pressing the jig while heating with a heater from behind.
[0006]
According to such a technique, it is possible to form a neat edge, but it is necessary to prepare a dressing band or to use a jig having a specific structure, and the process is complicated and takes time. There is a difficulty. Depending on the application of the bubble board, the edges often do not have to be correctly U-shaped in cross section. Therefore, there has been a demand for a technique that can close the end face of the bubble board by using a simpler method and gathering the common components of the device.
[0007]
[Problems to be solved by the invention]
In view of the above circumstances, an object of the present invention is to provide a method for realizing a process of closing an open end portion of a bubble board by a simple method and using an apparatus composed of common components. .
[0008]
[Means for Solving the Problems]
The method for closing an end face of a foam board according to the present invention that achieves the above object is to form a cap sheet having a large number of cap-shaped protrusions by molding a melt-extruded plastic sheet, and to the bottom and top surfaces of the cap A method for closing an open end face of a plastic foam board formed by attaching a flat back sheet and a liner sheet, as shown in FIG. 1, for example, an infrared heater (4) is disposed toward the end face of the foam board. The cap wall exposed to the end face and / or the cap wall (31) lined up near the end face, and the edge (11) and liner sheet of the back sheet (1) 2) After softening each part of the edge (21) as shown in FIG. 2 (the shaded area is heated to melt or soften) As shown in FIG. 3, the edge (11) of the back sheet and the edge (21) of the liner sheet are crimped by, for example, a crimping stand (5) and a crimping press (6) to close the end face. . FIG. 1 is represented by caps arranged near the end face, and the cap exposed at the end face is not shown. In the figure, reference numeral (3) represents a cap sheet.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Needless to say, there are various grades of foam board, thickness of cap sheet, back sheet and liner sheet, cap dimension (diameter x height), placement (density and pitch) Along with this, some changes are required in the way the end face is closed. Now, as the simplest grade classification, when discussing with the weight per unit area (1 m ² ) of the foam board product (called “meshing” in field terms), each sheet with a low weight of 800 g or 1500 g is thin. Therefore, softening due to irradiation with heat rays occurs easily, and there is no particular problem with the above-described crimping.
[0010]
On the other hand, in a bubble board with a high basis weight of 2000 g or more, since each sheet is thick, it takes time to advance softening by irradiation with heat rays. If it is not softened after sufficiently softening, the cap resists and requires a large force for pressure bonding. However, if too much time is taken for heating, not only the efficiency is deteriorated, but the air in the cap expands due to the heating, and the cap portion is swollen and the appearance of the product may be impaired.
[0011]
As a countermeasure, it is recommended that the cap wall exposed at the end face and / or the cap wall lined up near the end face is cut or provided with a notch and then irradiated with heat rays. FIG. 4 shows a case where a notch (32) is formed along a plane substantially parallel to the surface of the plastic bubble board prior to the irradiation of the heat ray, with respect to the wall of the cap arranged near the end face. The cut may not be made in the entire wall of the cap, but may be made only in a portion on the end face side of the wall. In any case, such a cut can be easily made by means of, for example, a rotary saw. The same effect as the notch can also be obtained by providing a notch (not shown) that cuts off the wall of the cap.
[0012]
If the above cuts are made or notches are provided, the strength of the cap will be reduced, and it will be possible to perform crimping with a small force, the air in the cap will be able to escape, No longer occurs. However, if a cap is cut or a notch is provided for a low-weight bubble board, the strength near the end face decreases, so it is usually advisable not to perform such processing. Should be determined according to the basis weight value, the physical properties of the material used, the use of the foam board, and the like.
[0013]
There may be several forms of the closed end surface formed by crimping the edges of the backsheet and the linersheet. The choice of whether the two sheets are brought together from both sides and crimped in the middle, or the edge of one sheet keeps its original position, i.e. it is not curved and the edge of the other sheet is curved and crimped This is because in either case, there is a choice of whether the degree of curvature of the sheet is abrupt or gradual. The recommended form is that the edge (11) of the backsheet retains its original position and the edge (21) of the liner sheet gradually approaches it as shown in FIG. Is a form in which the cross section is sandwiched between parallel lines and protrudes straight from the back sheet (we call it the “dolphin head” from the association of the form).
[0014]
The closed end face formed in accordance with the present invention need only have a constant and relatively narrow width in order to ensure closure and ensure the strength of the edge portion. Therefore, it is preferable to cut off the closed end face in order to make the dimensions of the product precise and enhance the beauty. The decorative cutting can be easily performed using an appropriate shearing blade or saw.
[0015]
The end surface closing treatment method of the present invention may be performed by a continuous method or by a batch operation. When the end face to be processed is relatively short, it is easy to construct a device that heats the whole or presses the whole at once, and it is advantageous to use batch operation. Specifically, an apparatus combining an infrared heater having a length corresponding to the length to be processed, a crimping table, and a crimping bar may be assembled. On the other hand, when the end surface to be processed is long, for example, when it is desired to continuously perform this closing process on the bubble board production line, the end surface of the bubble board is placed next to the heater provided with an appropriate length. A device is used that moves and presses the heated end face sequentially with a rotating roll to continuously press and bond.
[0016]
【The invention's effect】
The method for closing the end face of the foam board of the present invention does not require any other material such as a decorative band, can be easily implemented by a device that gathers common components, and ensures the open end of the foam board reliably and beautifully. Can be closed at a low cost. Since the air bubble board that has been closed by this method does not allow water or dust to enter the air bubble board, it can be used without problems as a material for containers that handle food, and it is desirable that the end face be closed. , Can be directed to any other use.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a heating step in an end face closing method for a plastic foam board according to the present invention.
2 is a cross-sectional view showing a portion softened by the heating process of FIG. 1;
FIG. 3 is a cross-sectional view showing a crimping process subsequent to a heating process.
FIG. 4 is a cross-sectional view showing a step of forming a cut or notch in a cap, which is performed in a modified embodiment of the end face closing processing method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Back sheet 11 Edge of back sheet 2 Liner sheet 21 Edge of liner sheet 3 Cap sheet 31 Wall of cap lined up near end face 32 Notch 4 Infrared heater 5 Crimp base 6 Crimp press

Claims (4)

A plastic foam board formed by molding a melt-extruded plastic sheet into a cap sheet having a large number of cap-shaped protrusions, and a flat back sheet and liner sheet pasted on the bottom and top surfaces of the cap. A method of closing an end face, which is irradiated with heat rays toward the end face and heated to expose the cap wall exposed to the end face and / or the cap wall lined up near the end face, and the edge of the backsheet and A method for closing an end face of a plastic foam board, comprising: softening each edge portion of a liner sheet and then crimping the edge of the back sheet and the edge of the liner sheet to close the end face. 2. The end face closing method according to claim 1, wherein the cap wall exposed at the end face and the cap wall arranged close to the end face are cut or provided with a notch and then irradiated with heat rays. The end face closure according to claim 1, wherein the edge of the back sheet and the edge of the liner sheet are crimped so that the edge of the back sheet retains its original position and the edge of the liner sheet forms a cross section gradually approaching it. Processing method. The end surface closing method according to claim 1, further comprising a step of cutting off the closed end surface formed by pressure bonding.

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