JP6554812B2 - Method for fixing a lid to a paper cup, method for producing a sealed paper container, and sealed paper container - Google Patents

Description

  The present invention relates to a method for fixing a lid to a paper cup, a method for manufacturing a sealed paper container, and a sealed paper container.

  In the packaging field for packaging food products, drinking water, etc., paper containers are widely used from the viewpoint of environmental friendliness.

  Improve oxygen barrier properties and water vapor barrier properties after sealing the opening of the paper container with a lid for the purpose of improving the protection function of the contents stored in the paper container and extending the expiration date of the contents. It is requested.

  In a paper container provided with a cylindrical body part in which both sides of a paper sheet material are bonded together to form a cylindrical shape, a step is generated at the bonding position. When a flange portion is formed at the upper end by winding the upper end periphery of the cylindrical body portion outward, a step is also formed in the flange portion. By simply heat-sealing the lid on the upper surface of the flange, the gap between the upper surface of the flange and the lid at the stepped portion may not be completely filled (not closed), and the paper container may not be sealed. .

  In order to achieve sealing, it is conceivable to enhance the sealing conditions (sealing heat quantity, sealing pressure and sealing time) of the lid. However, if the sealing conditions are strengthened, the adhesive strength of the lid becomes stronger, and it becomes difficult to open (peel) the lid. The lid can be easily opened (easy peelability, easy openability), and the contents can be easily taken out.

  In Patent Document 1, a thermoplastic resin laminated on a paper layer constituting a body part of a paper cup is provided so as to extend from a side edge of the body paper layer, and a step is formed by folding the extended thermoplastic resin. It is described that a large amount of thermoplastic resin is secured in the portion, and the step is eliminated by this large amount of thermoplastic resin. A large amount of thermoplastic resin is required, and a large amount of heat must be applied to melt a large amount of thermoplastic resin, which is costly. In addition, when a large amount of heat is applied, the adhesive strength between the lid material and the paper cup increases, resulting in lack of easy peel properties.

  Patent document 2 describes what joins a ring-shaped auxiliary | assistant flange board to the flange part of a paper container main body, and heat-seals a cover material to an auxiliary | assistant flange board. Since the ring-shaped auxiliary flange plate must be manufactured in addition to the paper container main body, this is also costly, and the joining process of the paper container main body and the ring-shaped auxiliary flange is separately required, so that the production efficiency is lowered.

Japanese Patent No. 5532939 Japanese Patent No. 4681694

  An object of the present invention is to provide a lid fixing method that can ensure sealing performance and that is excellent in manufacturing cost and production efficiency.

  Another object of the present invention is to fix the lid without gaps without completely sacrificing easy peelability (easy opening).

  The present invention also provides a method for manufacturing a sealed paper container, in which the lid member is fixed using the above-described fixing method, so that the sealing performance is ensured and the manufacturing cost and production efficiency are excellent, and the sealed paper container.

  According to the lid fixing method of the present invention, a step portion formed by bonding both side portions of a paper sheet material provided with a thermoplastic resin on one side with the one surface provided with the thermoplastic resin as an inner surface is provided. The flange portion of the paper cup having a body portion, a bottom portion that is fixed to the lower end of the body portion and closes the lower surface of the body portion, and a flange portion that is formed by winding the upper end periphery of the body portion outward. , For fixing a lid member provided with a thermoplastic resin on the inner surface, and covering the upper surface of the flange portion with the inner surface of the lid member so that the outer surface of the lid member extends along the entire upper surface of the flange portion. The lid material is heat-sealed to the upper surface of the flange portion by applying heat to the flange portion, the stepped portion of the flange portion and the vicinity thereof are internally heated, and the lid material in the range is attached to the flange portion. Is pressed toward the surface (pressing) it is characterized.

  A step portion having a height corresponding to the thickness of the sheet material is generated in the body portion formed by bonding both side portions of the sheet material. Since the flange portion is formed by winding the upper peripheral edge of the body portion outward, a step portion is also formed in the flange portion. The trunk may be cylindrical or rectangular. The flange portion may be flattened by being crushed outward and then lightly crushed from above and below.

  A lid member is fixed to the upper surface of the flange portion where the step portion is located. The fixing between the flange part and the cover material is realized by welding the thermoplastic resin of the flange part and the cover material. Since the flange portion is formed by outwardly winding the upper edge of the barrel portion provided with the thermoplastic resin on the inner surface, the outer surface (surface) of the flange portion exposes the thermoplastic resin. The lid member is put on the upper surface of the flange portion from the inner surface provided with the thermoplastic resin.

  By applying heat to the outer surface of the lid material along the entire upper surface of the flange portion, the lid material is heat sealed to the upper surface of the flange portion. According to the present invention, the stepped portion of the flange portion and the vicinity thereof are further internally heated and the lid member in the range is pressed toward the upper surface of the flange portion. Even when a gap remains between the lid material and the upper surface of the flange portion due to the step portion of the flange portion when heat sealing is finished, the step portion of the flange portion and the vicinity thereof are further heated and pressed internally. Therefore, the remaining gap between the lid member and the upper surface of the flange portion can be filled with the thermoplastic resin that is melted by the internal heat generation (the passage that penetrates into and out of the container can be eliminated). The sealed paper container is completely sealed, and the blocking effect (barrier effect) of oxygen, nitrogen, carbon dioxide, moisture (water vapor), etc. is greatly improved. In addition, since complete sealing is realized without using a large amount of thermoplastic resin, the manufacturing cost and production efficiency are excellent.

  Preferably, the heat sealing to the upper surface of the flange portion of the lid member is performed so as to exhibit easy peel properties. Since the body part is formed by bonding both side parts of the paper sheet material, there is one step part formed on the flange part, and the upper surface of the flange is flat except for this one step part ( There is no step). Even if heat sealing is performed so as to exhibit easy peelability, the lid material can be fixed to the upper surface of the flange portion without any gap except at the stepped portion. Here, if the lid material is heat-sealed to the upper surface of the flange part under conditions that exhibit easy peel properties (sealing heat quantity, sealing pressure, and sealing time), a gap is likely to occur at the stepped portion at the stage where the heat sealing is completed. As described above, the stepped portion of the flange portion and the vicinity thereof are further heated and pressed internally, so that the gap between the lid and the upper surface of the flange portion can be filled with a thermoplastic resin that melts by the internal heat generation. The lid material can be fixed to the entire top surface of the flange including the step portion without any gap. The lid can be peeled off from the upper surface of the flange portion with a light force except for the stepped portion of the flange portion and the vicinity thereof.

  In the case where a knob portion protruding outward is provided at a part of the periphery of the lid member, the lid member is placed on the upper surface of the flange portion so that the knob portion is located distal to the stepped portion of the flange portion. One of the lid member and the paper cup may be positioned when covering. When the lid is peeled from the top surface of the flange by grasping the knob by hand, it is possible to easily peel off the heat-sealed range with easy peel properties. For example, the knob portion may be positioned at a position farthest from the stepped portion of the flange portion (on the opposite side). However, in the case where the barrel is in the shape of a square tube, it is preferable in design to provide a knob for the lid at the corner of the barrel, so that the knob is located at the corner farthest from the stepped portion of the flange. May be positioned.

  For the internal heat generation, ultrasonic waves, high frequency or local heating can be used. In the flange portion where both sides of the sheet material are bonded, the thermoplastic resin, the sheet material, the thermoplastic resin, and the sheet material are arranged in this order from the outside (upper surface) to the inside. Internal heat generated by ultrasonic, high-frequency or local heating melts not only the outer thermoplastic resin but also the inner thermoplastic resin, thereby filling the gap generated in the stepped portion.

  The method for producing a sealed paper container according to the present invention comprises a step formed by bonding both side portions of a paper sheet material provided with a thermoplastic resin on one side, with the one surface provided with the thermoplastic resin as an inner surface. Forming a paper cup having a body portion having a portion, a flange portion formed by winding the upper end periphery of the body portion outward, and a bottom portion closing the lower end of the body portion; Put the contents, cover the top surface of the flange part with a cover with thermoplastic resin on the inner surface, and apply heat to the outer surface of the cover material along the entire top surface of the flange part. The lid material is heat-sealed on the upper surface of the flange portion, the stepped portion of the flange portion and the vicinity thereof are internally heated, and the lid material in the range is directed toward the upper surface of the flange portion. Wherein the pressure. For example, food or beverage can be stored in the paper cup. Since the lid member including the stepped portion is fixed to the upper surface of the flange portion without any gap, the contents do not come into contact with the outside air, and therefore the expiration date of the contents can be extended.

  The sealed paper container according to the present invention is bonded to the barrel portion having a flange portion formed at the peripheral edge of the upper edge, the bottom portion provided at the lower end of the barrel portion so as to close the lower surface thereof, and the upper surface of the flange portion, A lid member for closing the upper surface of the body part, wherein the body part is formed in a cylindrical shape by adhering both side parts of a paper sheet material, and the flange part is a peripheral edge at the upper end of the body part Indentation is formed on the surface of the lid material at the step part formed on the flange part by the bonding and the part bonded to the vicinity thereof. It is characterized by. Indentation is formed partially (locally) on the surface of the lid member when internally generating heat and pressing the stepped portion of the flange portion and the vicinity thereof. A stepped portion is located at a location where the indentation is formed.

It is a perspective view of a sealed paper container. It is a partially cutaway front view of the sealed paper container along the II-II line of FIG. It is sectional drawing of the cover material and flange part before welding. It is sectional drawing of the cover material and flange part after heat sealing. It is sectional drawing of the cover material and flange part after ultrasonic sealing.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  1 and 2 show a sealed paper container. 1 is a perspective view of the sealed paper container, and FIG. 2 is a partially cutaway front view of the sealed paper container along the line II-II in FIG.

  The sealed paper container 1 includes a lid member 10, a trunk portion (tubular portion) 12, and a bottom portion 13.

  The body 12 of the container 1 has a cylindrical shape with a large diameter at the top and a diameter that decreases as it goes down. The entire peripheral edge of the upper end of the trunk 12 is wound outward and is crushed slightly flat, thereby having an outward spread. Hereinafter, the annular portion that spreads outward at the upper end of the body portion 12 is referred to as a flange portion 11. The bottom part 13 is circular, and its peripheral part is bent downward (bent part 13A). The bottom portion 13 fits snugly into the lower surface opening of the body portion 12, and the lower end portion of the body portion 12 is folded back inside (folded portion 12A), and the folded portion 12A sandwiches the bent portion 13A of the bottom portion 13. Both the inner and outer surfaces of the bent portion 13A of the bottom portion 13 and the inner surface of the folded portion 12A at the lower end portion of the body portion 12 sandwiching the bent portion 13A are bonded or welded with a thermoplastic resin without a gap.

  The body 12 of the container 1 is formed in a cylindrical shape by bonding the left and right sides of a sheet material (blank) formed in an arc shape, and then the upper peripheral edge is rolled outward and then flattened from above and below. In addition, the lower end portion is bent inward. The bonding portion between the side portions of the blank material is welded by adhesion or thermoplastic resin. The bonding portion is provided from the flange portion 11 to the body portion 12 of the container 1. In the following description, the portion located outside of the double stacked sheet material constituting the bonded portion of the flange portion 11 is referred to as the outer flange end portion 11L and is located inside the outer flange end portion 11L. This portion is referred to as an inner flange end portion 11R. A stepped portion 11A having a height corresponding to the thickness of the blank sheet material is generated in the bonded portion.

  The body portion 12 (including the flange portion 11) and the bottom portion 13 are composed of a base material and a protective layer, and a thermoplastic resin layer (thermal welding resin layer, sealant layer) for welding provided on the innermost surface. The substrate is mainly composed of paper, and may have a laminated structure in which a coat layer or the like is provided on the surface of the paper. The protective layer can include a thermoplastic resin layer, a metal layer, and the like. For example, the body 12 is formed by laminating paper / PE (polyethylene) / AL (aluminum) / PE in this order from the outer surface (outer layer) to the inner surface (inner layer), paper / PE / AL / DL. (Dry laminate) / PET (polyethylene terephthalate) / PE laminated in this order can be used. The innermost PE is used for welding. The bottom 13 is formed by laminating paper / PE / AL / PE / LLDPE (linear low density polyethylene) in this order from the outer surface to the inner surface, paper / PE / AL / DL / PET / PE / What laminated | stacked LLDPE in this order can be used. Needless to say, the laminated structure of the body portion 12 and the bottom portion 13 can be appropriately changed according to the type of contents stored in the container 1, the required storage period of the contents, and the like. Here, since the flange portion 11 is formed by winding the upper end of the body portion 12 outward (see FIG. 2), the inner surface of the body portion 12 becomes the outer surface of the flange portion 11 and is a thermoplastic resin layer for welding. (PE) is the outermost layer in the flange portion 11.

  The lid member 10 has a circular shape that is slightly larger than the size (diameter) of the upper end opening of the trunk portion 12, and closes the entire upper end opening of the trunk portion 12. A triangular knob 10B for facilitating pinching of the lid member 10 is formed on a part of the outer edge of the lid member 10 so as to protrude outward.

  The lid member 10 is also composed of a base material mainly composed of paper, a protective layer provided on the inner surface of the base material, and a thermoplastic resin layer (thermal welding resin layer, sealant layer) for welding. For example, paper / PE (polyethylene) / AL (aluminum) / PE laminated in this order from the outer surface (outer layer) to the inner surface (inner layer) of the cover material 10, paper / DL / AL / DL / PET / What laminated | stacked PE in this order etc. can be used. The innermost PE is used for welding. Needless to say, the laminated structure of the lid member 10 is not limited to these.

  As described in detail below, the lid member 10 is sealed on the upper surface of the flange portion 11 in two steps (two stages). The first step is a step of covering the upper surface of the flange portion 11 with the inner surface of the cover member 10 and applying heat to the outer surface of the cover member 10 along the entire upper surface of the flange portion 11 (hereinafter referred to as normal seal or normal seal). Process). Normally, the sealing step is performed to such an extent that the lid member 10 can be easily peeled off from the flange portion 11 (maintaining easy peel properties) (details will be described later). Of course, it goes without saying that the contents, such as food or beverage, are put into the internal space partitioned by the body 12 and the bottom 13 from the upper end opening of the body 12 prior to the normal sealing process.

  The second step is a step in which ultrasonic waves, high frequencies, or heat is applied to the lid member 10 at the portion covering the stepped portion 11A of the flange portion 11 from the outer surface thereof (hereinafter, referred to as “high pressure”). Point seal or point seal process). The point seal process is performed, for example, in a range of width 0.5 cm on both sides of the center (center) where the step portion 11A on the upper surface of the flange portion 11 is formed. The point seal process is performed relatively strongly to the extent that the lid member 10 cannot be easily peeled off from the flange portion 11 (details will be described later).

  An indentation (concave portion) 10A appears in the range of the point-sealed lid member 10. For example, when applying ultrasonic waves, the tip of the resonator (horn) is pressed against the lid member 10, and at this time, a fine depression (indentation) 10A is formed. Even when high frequency or heat is applied, an indentation 10A appears on the lid member 10. Since the point seal is performed locally, the indentation 10A also appears locally. A step portion 11A is located in the range of the indentation 10A.

  3 to 5 show the state of sealing between the lid member 10 and the upper surface of the flange portion 11 described above, and a part of the lid member 10 and a part of the flange portion 11 along the line V-V in FIG. FIG. FIG. 3 shows a state before sealing, FIG. 4 shows a state where a normal sealing process is performed, and FIG. 5 shows a state where a point sealing process is performed. In FIG. 3 to FIG. 5, for the sake of easy understanding, the lid member 10 and the flange portion 11 are both shown as having a two-layer structure of a paper layer and a thermoplastic resin layer.

  With reference to FIG. 3, as described above, the outer flange end portion 11L and the inner flange end portion 11R overlap each other at the bonded portion of the flange portion 11, and there is a step portion 11A.

  Referring to FIG. 4, the cover member 10 is placed on the upper surface of the flange portion 11, and heat is applied to the entire outer peripheral portion of the cover member 10 (normally seal). The thermoplastic resin 15 on the inner surface of the lid member 10 and the thermoplastic resin 15 on the upper surface of the flange portion 11 are melted by the heat applied through the lid member 10.

  Here, in the pasted portion, the thermoplastic resin 15 laminated on the inner surface of the lid member 10 and the outer flange end portion 11L can be sufficiently transferred with heat, but can be melted by the inner flange located inside these. The thermoplastic resin 15 laminated on the end portion 11R hardly melts. In order to ensure easy peelability, the amount of heat (seal temperature) applied to the lid member 10 in the heat sealing process, the pressure when the lid member 10 is pressed against the upper surface of the flange portion 11 (seal pressure), and This is because the time (sealing time) cannot be made so long (long) and there is a paper layer on the outer flange end portion 11L. In order to ensure easy peelability, for example, a sealing temperature of 160 ° C., a sealing pressure of 0.2 Mpa, and a sealing time of 1 second are employed as sealing conditions.

  The thermoplastic resin 15 laminated on the lid member 10 and the outer flange end portion 11L flows into the gap between the lid member 10 and the upper surface of the flange portion 11 generated by the step portion 11A. However, if the entire gap cannot be filled with the thermoplastic resin 15 melted by heat sealing, a small gap 20 remains. The gap 20 serves as a passage connecting the inside and the outside of the container 1. When heat sealing is performed so as to exhibit easy peel properties as described above, there is a high possibility that the gap 20 is generated in the stepped portion 11A.

  Then, point seal is performed next. Referring to FIG. 5, for example, ultrasonic waves are applied partially (locally) to the lid member 10 at the portion covering the step portion 11 </ b> A of the flange portion 11 (ultrasonic seal). In the range where the ultrasonic wave is applied, in addition to the thermoplastic resin 15 laminated on the lid 10 and the outer flange end portion 11L, the thermoplastic resin 15 laminated on the inner flange end portion 11R also melts due to internal heat generation. . The thermoplastic resin 15 laminated on the inner flange end portion 11R also flows, so that the gap 20 remaining during normal sealing is filled with the thermoplastic resin 15. As described above, the indentation 10A remains on the lid member 10 in the range where the ultrasonic waves are applied.

  The molten thermoplastic resin 15 is then naturally cooled to be cured, whereby the lid member 10 is welded to the upper surface of the flange portion 11 without any gap including the stepped portion 11A.

  In the point-sealed range (the range where the indentation 10A appears), the lid 10 and the upper surface of the flange 11 are sealed relatively strongly. On the other hand, in other ranges, as described above, the lid member 10 and the upper surface of the flange 11 exhibit easy peel properties. In order to make it easy to peel off the cover material 10 that has been welded with an easy peel property, the knob 10B, which is gripped when the cover material 10 is peeled off from the flange 11 and triggers the peeling, has a point seal range. It is arranged as far as possible (distal) from (the expression range of the indentation 10A), preferably on the opposite side (see FIG. 1). However, if the force is relatively strong, the lid member 10 can be completely peeled off from the flange portion 11. When the cover material 10 is forcibly peeled off with a strong force, the base material (paper material) included in the cover material 10 or the flange portion 11 is exposed in the point seal range.

  Table 1 shows the results of the barrier evaluation test.

  In the barrier evaluation test, a paper container sample in which the lid 10 was welded to the upper surface of the flange portion 11 only with a normal seal was compared with a paper container sample (the paper container of the present invention) that was point-sealed in addition to the normal seal. . All samples were sealed with an oxygen scavenger in the container, and the lid 10 was sealed. After leaving for one day and night, the presence or absence of decompression was confirmed. The lid member 10 and the upper surface of the flange portion 11 are welded without a gap, and therefore, a completely sealed paper container sample is dented in the body portion 12 when the inside of the container is depressurized by an oxygen scavenger. On the other hand, if there is even a slight gap (passage through the inside and outside of the container) between the top surface of the flange portion 11 of the lid member 10, the inside of the container is not depressurized, so that no dent is generated. Thereby, the presence or absence of pressure reduction can be confirmed. The container sample in which the reduced pressure is confirmed is a sealed container, and the container sample in which the reduced pressure cannot be confirmed is a container having a gap.

  Table 1 shows a paper container sample in which the lid 10 is welded to the upper surface of the flange portion 11 only with a normal seal (normal seal only), and a paper container sample with a point seal in addition to the normal seal (normal seal + point seal) For each of the above, the number of container samples for which no decompression was confirmed (no dent) was shown in the numerator (left side), and the number of samples tested was shown in the denominator (right side). It can be seen that the paper container that is normally kept only in the seal does not cause any pressure reduction for all the samples, and there is a gap between the lid 10 and the upper surface of the flange portion 11. On the other hand, in the case of paper containers that were point-sealed in addition to normal sealing, decompression occurred for all samples. The paper container sample (the paper container of the present invention) that has been point-sealed in addition to the normal seal is completely sealed with no gap between the lid 10 and the upper surface of the flange 11 including the stepped portion 11A. I understand that

1 Sealed paper container
10 Lid
10A indentation
10B knob
11 Flange
11A Stepped part
12 Torso
13 Bottom
15 Thermoplastic resin

Claims (7)

A body having a step portion formed by bonding both sides of a paper sheet material provided with a thermoplastic resin on one side with the one surface provided with the thermoplastic resin as an inner surface, and a lower end of the body A thermoplastic resin is provided on the inner surface of the flange portion of the paper cup that has a bottom portion that is fixed to the bottom portion and closes the lower surface of the barrel portion, and a flange portion that is formed by winding the upper edge of the barrel portion outward. A method of fixing the lid,
Cover the top surface of the flange with the inner surface of the lid.
Heat-sealing the lid on the flange top surface by applying heat to the outer surface of the lid material along the entire top surface of the flange portion;
The above-mentioned step portion of the flange portion and the vicinity thereof are internally heated, and the cover member in that range is pressed toward the upper surface of the flange portion
Lid fixing method. The heat sealing of the lid material on the upper surface of the flange portion is performed so as to exhibit an easy peel property.
The lid fixing method according to claim 1. A knob portion protruding outward is provided on a part of the periphery of the lid member,
Positioning the lid or the cup when the lid is placed on the upper surface of the flange so that the knob is located distal to the stepped portion of the flange;
The lid fixing method according to claim 1 or 2. Causing the internal heat generation by applying ultrasonic waves from the outer surface to the stepped portion of the flange portion of the lid and the portion covering the vicinity thereof,
The lid fixing method according to any one of claims 1 to 3. Causing the internal heat generation by applying a high frequency from the outer surface to the stepped part of the flange part of the lid and the part covering the vicinity thereof,
The lid fixing method according to any one of claims 1 to 3. Causing the internal heat generation by locally heating the stepped portion of the flange portion of the lid and the portion covering the vicinity thereof from the outer surface thereof,
The lid fixing method according to any one of claims 1 to 3. A body having a step portion formed by bonding both sides of a paper sheet material provided with a thermoplastic resin on one side, with the one surface provided with the thermoplastic resin as an inner surface, and an upper end of the body Forming a paper cup comprising a flange portion formed by winding the periphery outward, and a bottom portion closing the lower end of the body portion;
Put the contents into the paper cup from the top opening,
Cover the upper surface of the flange part with a cover material with a thermoplastic resin on the inner surface.
Heat-sealing the lid on the flange top surface by applying heat to the outer surface of the lid material along the entire top surface of the flange portion;
The above-mentioned step portion of the flange portion and the vicinity thereof are internally heated, and the cover member in that range is pressed toward the upper surface of the flange portion
Manufacturing method of sealed paper container.

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