JPH08133207A - Method for hermetically sealing liquid paper container - Google Patents

Abstract

PURPOSE: To reliably seal even a liquid container having a polyester-based sealing layer in the inner surface thereof with respect to a method for hermetically sealing a liquid paper container in a sealing process in a liquid-filling device. CONSTITUTION: Firstly, inner sealing surfaces 21 previously provided on an inner surface 2 of an open part of a liquid paper container 1 shaped into a square tube form are so folded as to be proximately opposed to each other. Next, the opposed inner sealing surfaces 21 are contact bonded to each other from outside, and a high-frequency electromagnetic wave is applied to a metal film provided under the inner sealing surfaces 21. An inner layer material of a thermoplastic resin or the like forming the inner sealing surfaces 21 is heated through the metal film for hermetically sealing a liquid paper container.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hermetically sealing a liquid paper container used in a sealing process in a liquid filling device. In particular, the present invention relates to an improvement in reliably sealing even a liquid container having a polyester-based sealing layer on its inner surface.

[0002]

2. Description of the Related Art A liquid filling apparatus for filling a liquid such as juice has a structure in which liquid paper containers stacked in layers are formed into a rectangular tube shape, and the bottom portion of the liquid paper container is heat-sealed to remove the liquid paper container. It is an automatic line that sterilizes the inside and outside surfaces, fills a liquid paper container with liquid, heat-seals the top part of the liquid paper container, and sends it out. In this process, the bottom heat-sealing process and the top heat-sealing process are
It is manufactured by the same procedure, and the heat sealing process of the bottom part will be described as an example.

Referring to FIG. 2, in FIG. 2, 1 is a liquid paper container, 21 is an inner sealing surface, 31 is an outer adhesive surface, and a dashed line indicates a fold line. White arrows indicate the order of steps.

In the heating process, the inner sealing surface 21 and the outer bonding surface 3 which are predetermined areas near the edge of the opening of the liquid paper container.
Hot air is blown as indicated by arrows on 1 and to heat.

In the temporary folding step, the liquid paper container 1 is folded along the creases formed in advance and is temporarily folded into the shape of the bottom portion.

In the pressing process, pressure is applied by pressing in the direction indicated by the arrow.

FIG. 3 shows the layer structure of the container material used for the liquid paper container 1.

Referring to FIG. 3, in FIG. 3, 11 is a container core made of paper or the like.
Reference numeral 2 is a metal film of aluminum or the like, which is laminated via 13 plastic layers. When the container material is a liquid container having a rectangular tube shape, the metal film 12 is placed inside the tube. An outer layer material 14 is formed in contact with the container core material 11. Reference numeral 15 denotes an inner layer material, which is formed in contact with the metal film 12.

As the outer layer material 14 and the inner layer material 15, since a sealant such as a thermoplastic resin which is solid at room temperature and melts by heating and has an adhesive ability is used, the heating step of the liquid filling device (see FIG. 2 again). In, the sealant such as thermoplastic resin is melted by the hot air, and in the pressing step (see FIG. 2 again), the overlapping inner sealing surfaces 21 of the liquid paper container 1 are sealed by the pressure bonding by the press, and the overlapping outer bonding surfaces 31 The two are glued together. Then, the sealing of the enclosed liquid and the formation of the shape of the liquid paper container are completed.

[0010]

Polyethylene has been often used as a sealant for thermoplastic resins, but polyester may be used as the inner layer material 15. Polyester has the advantage that it is less adsorbable for the aroma compounds of the contents, and has the advantage that the odor of polyester is less likely to attach to the contents, and is used especially when the odor is disliked. By the way, a liquid paper container having polyester as the inner layer material 15 is heated with hot air to the inner sealing surface 21 and the outer bonding surface 31, which are predetermined regions,
Then, even if pressure bonding is performed by pressing, the melted polyester may be crystallized between the heating and the pressing, and it may not be possible to reliably seal the polyester.

An object of the present invention is to solve this problem, and it is possible to reliably seal even a material such as polyester which can be crystallized in a relatively short time by heating. It is to provide a sealing method.

[0012]

In order to solve the above problems, first, an inner sealing surface (21) provided in advance on the inner surface (2) of the opening of the liquid paper container (1) formed in the shape of a rectangular tube is provided. The inner sealing surfaces (21) facing each other are bent so as to be close to each other, and then the opposing inner sealing surfaces (21) are pressure-bonded from both outer sides, and high-frequency electromagnetic waves are applied to the metal film (12) inscribed in the inner sealing surfaces (21). Is applied to heat the inner layer material (15) made of a thermoplastic resin or the like that constitutes the inner sealing surface (21) through the metal film (12), thereby achieving a hermetic sealing method for a liquid paper container.

Then, following the step of heating the inner sealing surface (21), hot air is blown to the outer bonding surface (31) provided in advance on the outer surface (3) of the opening to blow the outer bonding surface (31). If the outer layer material (14) made of a thermoplastic resin or the like which constitutes 31) is heated and the outer adhesive surface (31) is superposed and pressure-bonded, the outer shape of the liquid paper container can be regulated. It is convenient for transportation and storage.

[0014]

The method of hermetically sealing a liquid paper container according to the present invention is
First, the inner sealing surfaces 21 provided in advance are made to face each other and bent so as to be close to each other, and then, the inner sealing surfaces 21 that face each other are pressure-bonded from both outsides, so that the inner sealing surface 21 of the liquid paper container 1 is pressed. It is known that a high frequency electromagnetic wave is applied to the metal film 12 inscribed in, and the inner layer material 15 is heated through the metal film 12.

When a high frequency electromagnetic wave is applied, an eddy current flows through the metal film 12 in the field of the high frequency electromagnetic wave by electromagnetic induction, and the metal film 12 is heated by the eddy current. This heat is conducted to the inner layer material 15. At this time, pressure is applied to the inner sealing surfaces 21 facing each other, so that the inner layer materials 15 melted by the conducted heat adhere to each other. Unlike the prior art, since the time from melting to pressing is short, even if the inner layer material 15 is polyester, it adheres before crystallization. For this reason, it is surely sealed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for hermetically sealing a liquid paper container according to an embodiment of the present invention will be described below in more detail with reference to the drawings.

Referring to FIG. 1, FIG. 1 is a process diagram illustrating the process of hermetically sealing the bottom portion of a liquid paper container according to a procedure. The white arrows indicate the order of steps. In FIG. 1, 1 is a liquid paper container, and a metal film 1 is provided on the inner surface side of a container core material 11 (see FIG. 2 again).
2 (see FIG. 2 again), an inner layer material 15 (see FIG. 2 again) made of a sealant that is melted by heating such as a thermoplastic resin and has an adhesive ability, and an outer layer material 14 (see FIG. 2 again). Two
Is the inner surface of the opening of the upper and lower openings of the liquid paper container 1 formed in the shape of a rectangular tube, and 21 is the surface of the inner surface 2 of the opening which is bonded at the time of sealing. It is an inner sealing surface up to a specified range. 3 is an outer surface of the opening, 31 is a surface in the outer surface 3 of the opening, which is adhered when the outer shape of the liquid paper container 1 is formed, and is an outer adhering surface up to a predetermined range from the edge of the opening. . The alternate long and short dash line indicates a fold line.

In step A, the inner sealing surfaces facing each other of the inner surface 2 of the opening of the bottom portion (the bottom portion is arranged at the top of the drawing for convenience of explanation) of the liquid paper container 1 formed into a rectangular tube shape. 21 is bent so as to overlap in a V shape when viewed from above, and is supported so as to maintain this state.

In step B, a sealing jaw (not shown) having a pressure plate and a high frequency electromagnetic wave transmitter is used,
While the inner sealing surface 21 is overlapped in a V shape, the high frequency electromagnetic wave generator is actuated by applying pressure from both outer sides as shown by the arrow, and the high frequency electromagnetic wave is applied to the metal film 12 inscribed in the inner sealing surface 21. Apply. Then, the operation of the high frequency electromagnetic wave generator is stopped after a predetermined period of time, and the pressurization is stopped after a predetermined period of time to remove the seal jaws from the liquid paper container 1.

In this step B, an induced eddy current caused by a high frequency electromagnetic wave flows through the metal film 12 forming the liquid paper container 1 and the metal film 12 is heated. The inner layer material 15 in contact with the metal film 12 is also heated by heat conduction and melted. And since it is pressurized before the application of high frequency electromagnetic waves,
The inner sealing surfaces 21 that are overlapped are bonded to each other,
The sealing is completed when the heating is completed and the pressurization is completed. Sealing is reliable because the sealant, even polyester, is adhered before it crystallizes because melting and pressing are performed simultaneously.

In step C, hot air is blown to the outer adhesive surface 31 of the liquid paper container 1 in the direction of the arrow to heat the outer adhesive surface 31. The outer layer material 14 on the outer adhesive surface 31 is in a molten state.

In step D, a press pad (not shown) is pressed from both inner and outer surfaces of the bottom portion of the liquid paper container 1 as indicated by an arrow, and the outer adhesive surfaces 31 are pressed against each other. By this process D, the overlapping outer adhesive surfaces 31 are bonded to each other, and the bottom portion of the liquid paper container 1 is molded.

By the above procedure, the process of hermetically sealing the bottom portion of the liquid paper container 1 is completed.

The step of hermetically sealing the top part of the liquid paper container 1 may be steps A and B when the top part is a gable top type (sloping roof type), and when the top part is a flat top type. Steps A to D may be the same as in the bottom portion. However, if the overlapping part of the flat top has a shape that can be bent not only to the upper surface but also to the side surface of the square tube,
In step C, hot air is blown even to the outer bonding surface 31 corresponding to this shape, and in step D, the side surfaces of the rectangular tube corresponding to this shape are also pressed from the inner and outer surfaces.

[0025]

As described above, according to the method for hermetically sealing a liquid paper container according to the present invention, since heating and pressurization are performed without delay between the portions of the adhesive surface, the liquid paper container Even if the inner layer material of (3) is a material that is rapidly crystallized, such as polyester, since it is bonded before crystallization, reliable sealing is realized.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method for hermetically sealing a liquid paper container according to an embodiment of the present invention.

FIG. 2 is a process drawing showing a method for hermetically sealing a liquid paper container according to a conventional technique.

FIG. 3 is a layer configuration diagram of a liquid paper container.

[Explanation of symbols]

 1 Liquid Paper Container 2 Inner Surface of Opening 3 Outer Surface of Opening 11 Container Core Material 12 Metal Film 13 Plastic Layer 14 Outer Layer Material 15 Inner Layer Material 21 Inner Sealing Surface 31 Outer Adhesive Surface

Claims (2)

[Claims] 1. First, the inner sealing surfaces (21) provided in advance on the inner surface (2) of the opening of the liquid paper container (1) formed in the shape of a rectangular tube are made to face each other so that they are close to each other. Bending, then, the inner sealing surfaces (21) facing each other are pressure-bonded from both outer sides, and the metal film (1) inscribed in the inner sealing surfaces (21) is inscribed.
A liquid paper container characterized in that a high frequency electromagnetic wave is applied to 2) to heat an inner layer material (15) made of a thermoplastic resin or the like which constitutes the inner sealing surface (21) through the metal film (12). Sealing method of. 2. Subsequent to the step of heating the inner sealing surface (21), hot air is blown to the outer adhesive surface (31) provided in advance on the opening outer surface (3) to blow the outer adhesive surface (31). Outer layer material (1) made of a thermoplastic resin or the like constituting
4. The method for hermetically sealing a liquid paper container according to claim 1, wherein 4) is heated and the outer adhesive surface (31) is superposed and pressure-bonded.