JP2020007022A - Paper container for liquid - Google Patents

Abstract

To provide a paper container for liquid in which pinholes and foam never occur, and leakage of contents and defective appearances do not occur easily, even when heated air is blown at the time of welding for sealing of a bottom portion and a top portion.SOLUTION: In a paper container for liquid which is constituted by a sealant layer 11 which is placed in the inner face side of a paper base 13, and a layered body 10 where a resin layer 14 is placed in the outer face side, air gap portions 16 are provided between the paper base and the sealant layer. A temperature rise of the paper base is inhibited at the time of heat-sealing by a heat insulation effect of the air gap portion, so that discharge of water vapor from the paper base is inhibited.SELECTED DRAWING: Figure 1

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper container for storing a liquid, and more particularly to a liquid paper container in which leakage of contents hardly occurs and appearance defects are less likely.

  BACKGROUND ART Paper containers for storing liquids are known in various shapes and have been put to practical use. Patent Literature 1 discloses a liquid paper container that is one of them, a so-called Goebel top type.

  The gobel-top type liquid paper container is obtained by bending a blank 70 as shown in FIG. 7 and sealing both ends of each other to form a rectangular tube, sealing one of the openings as a bottom, and then sealing the liquid content. An object is filled and finally the top part is sealed and formed. In the figure, 70A indicates a portion constituting the body of the liquid paper container of the blank 70, 70B indicates a portion constituting the bottom portion, and 70C indicates a portion constituting the top portion, respectively.

  This liquid paper container is usually composed of a laminate using paper as a structural support (substrate). FIG. 8 shows a typical layer structure, that is, a laminate 80 is formed by laminating an intermediate layer 83 for preventing the permeation of a liquid content through an adhesive layer 82 on the inner surface side of a paper base 81. The sealant layer 84 is laminated on the inner surface side of the intermediate layer 83. An outer resin layer 85 is provided on the outer surface of the paper base 81. In the drawing, a1 and a2 indicate printing ink layers arranged on the inner and outer surfaces of the paper base material 81.

  By the way, when the bottom portion is sealed or the top portion is sealed using such a blank 70, heated air is blown to a predetermined position of the blank 70 to melt the sealant layer 84. The sealed sealant layers 84 are sealed by pressing each other. That is, when the step of sealing the top portion is illustrated, as shown in FIG. 9, the nozzle 90 is inserted into the opening of the rectangular tubular blank, and the top portion is formed from the heated air ejection hole provided at the tip thereof. The heated air is blown toward the inner surface of the portion 70C. Then, after the nozzle 90 is withdrawn, the heated and melted sealant layers 84 are bonded to each other by pressing with a jig (not shown) from the outer surface side of the portion 70C constituting the top portion.

  When the bottom portion and the top portion are sealed as described above, the paper air 81 is also heated by the heated air to blow the heated air. Generally, since the paper base material 81 contains moisture, the water vapor evaporated by the heating expands, and a pinhole may be formed in the intermediate layer 83 or the sealant layer 84 in some cases. Further, even without generation of pinholes, a foaming phenomenon in which the intermediate layer 83 and the sealant layer 84 swell inside the container may occur. When a pinhole is generated in the intermediate layer 83 or the sealant layer 84 as described above, or when a foaming phenomenon occurs without reaching the pinhole, the liquid content infiltrates the paper base material 81 and the like. As a result, the quality as a liquid paper container was spoiled.

JP 2007-176538 A

Therefore, the present invention is directed to a liquid paper that is free from pinholes and foaming even when heated air is blown at the time of welding for sealing the bottom portion and the top portion, and is unlikely to cause leakage of contents and poor appearance. It is intended to provide a container.

In order to solve the above problems, the invention according to claim 1 of the present invention is:
In a liquid paper container composed of a laminate in which a sealant layer is disposed on an inner surface side of a paper base material and a resin layer is disposed on an outer surface side, a gap is provided between the paper base material and the sealant layer. It is a liquid paper container.

The invention according to claim 2 of the present invention
2. The liquid paper container according to claim 1, wherein the void is formed in an uneven recess provided on an inner surface side of the paper base. 3.

In addition, the invention according to claim 3 of the present invention provides:
3. The liquid paper container according to claim 1, wherein an intermediate layer is provided between the paper base material and the sealant layer. 4.

The invention according to claim 4 of the present invention is
4. The liquid paper container according to claim 3, wherein the void is formed in a concave and convex portion provided on the paper base side of the intermediate layer. 5.

Further, the invention according to claim 5 of the present invention,
The liquid paper container according to claim 3, wherein the intermediate layer is a gas barrier layer.

  According to the present invention, due to the heat insulating effect of the voids, heat due to the heated air is hardly transmitted to the paper substrate, the evaporation of moisture from the paper substrate is suppressed, and the occurrence of pinholes and foaming phenomenon can be suppressed. Thus, it is possible to provide a liquid paper container free from leakage of contents and poor appearance.

It is sectional drawing of the laminated body which comprises one Embodiment of the liquid paper container of this invention. It is sectional drawing of the laminated body which comprises 2nd Embodiment of the liquid paper container of this invention. It is sectional drawing of the laminated body which comprises 3rd Embodiment of the liquid paper container of this invention. It is sectional drawing of the laminated body which comprises the 4th Embodiment of the liquid paper container of this invention. FIG. 4 is a cross-sectional view illustrating a layer configuration of a laminate of Comparative Example 1. FIG. 9 is a cross-sectional view illustrating a layer configuration of a laminate of Comparative Example 2. It is a development view of the blank of the conventional liquid paper container. It is sectional drawing which shows the layer structure of the laminated body which comprises the conventional liquid paper container. FIG. 11 is a diagram showing a state in which heated air is blown toward the inner surface of a conventional liquid paper container.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below.

  FIG. 1 is a cross-sectional view of a laminate constituting one embodiment of the liquid paper container of the present invention. The laminate 10 is provided with an outer resin layer 14 on the surface of the paper base 13 on the outside of the liquid paper container, and the adhesive layer 12 on the surface of the paper base 13 on the inner side of the liquid paper container. Thus, the sealant layer 11 is sequentially laminated. Each layer may be laminated by any known method. Although not shown, an intermediate layer may be provided between the paper base 13 and the sealant layer 11.

  A printing ink layer 15 is provided on the outer surface of the outer resin layer 14. The printing ink layer 15 is not an essential element of the present invention, and its position and number are arbitrary. For example, it can be arranged on the inner surface side of the outer resin layer 14 or on the inner surface side of the paper base material 13. Moreover, it can also be arrange | positioned in multiple places.

  The surface on the inner surface side of the paper base material 13 is formed with irregularities, and the concave portion is a gap portion 16 and is filled with air. When a liquid paper container is prepared from a blank prepared by using the laminated body 10, when a predetermined portion of the blank such as a bottom portion and a top portion is bonded and heated air is blown to seal the container, a gap 16 is formed. Since it is filled with air and has a lower thermal conductivity than other resin materials, it acts as a heat insulating layer for heat conducted from the sealant layer 11 side and exhibits a heat insulating effect. As a result, it becomes difficult for the heat of the heated air to be transmitted to the paper base 13, and the temperature rise of the paper base 13 is suppressed, so that the release of water vapor from the paper base 13 can be suppressed.

  For this reason, the laminate 10 can suppress the occurrence of pinholes and the occurrence of a foaming phenomenon in the sealant layer 11 which is likely to be caused by the influence of water vapor released from the paper base material 13, resulting in poor liquid leakage and appearance. It is possible to form a liquid paper container that is unlikely to cause defects.

  As the paper base material 13, a paperboard having a strength required for a liquid paper container, such as stiffness and tear strength, and an appropriate thickness can be suitably used, and the concave portion is provided as the void portion 16 as described above. In this case, it is preferable to have a thickness necessary for providing the gap portion 16. The method for providing the concave portion in the paper base material 13 is not particularly limited, but it can be formed by embossing. Alternatively, a concave portion may be cut off by cutting. The gap 16 is formed by laminating another layer by lamination or the like on the surface where the concave portion is formed.

  The gaps 16 are formed by the air remaining in the concave portions formed as described above, but the gaps 16 may be independent or communicate with each other.

  An outer resin layer 14 provided on the surface of the paper substrate 13 on the outer side of the liquid paper container protects the paper substrate 13, imparts water resistance to the laminate 1, and protects the laminate 1 from dirt and damage. have. Further, when a liquid paper container is formed and folded in accordance with its shape, it is melted by heating when bonding the outer surfaces to form a welded layer.

  Examples of such an outer resin layer 14 include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, ethylene-based resins such as ethylene-α-olefin copolymer, and homo-block random. Each polypropylene resin and a propylene-based resin such as a propylene-α-olefin copolymer can be used. It is also possible to use polyethylene terephthalate resin, polybutylene terephthalate resin, polyamide resin and the like.

  The adhesive layer 12 can be made of, for example, a urethane-based adhesive, an acrylic-based adhesive, or an epoxy-based adhesive.

  The sealant layer 11 is a layer necessary for thermally bonding the sealant layers 11 to each other to form a sealed liquid paper container. As the sealant layer 11, a polyethylene resin or a polypropylene resin can be used. Specifically, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, ethylene-based resins such as ethylene-α-olefin copolymer, homo-block random polypropylene resins, propylene Propylene resins such as α-olefin copolymers, ethylene-α, β unsaturated carboxylic acid copolymers such as ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer, ethylene-methyl acrylate and ethylene- Esterified products of ethylene-α, β-unsaturated carboxylic acid copolymers such as ethyl acrylate, ethylene-methyl methacrylate and ethylene-ethyl methacrylate, ethylene-α, Ion crosslinked product of β-unsaturated carboxylic acid copolymer, ethylene-maleic anhydride Acid anhydride-modified polyolefins represented by terpolymers such as in-acid graft copolymers and ethylene-ethyl acrylate-maleic anhydride, epoxy compound-modified polyolefins such as ethylene-glycidyl methacrylate copolymer, ethylene- A single resin or a blend of two or more resins selected from vinyl acetate copolymers can be exemplified.

  The sealant layer 11 may be a sealant film previously formed into a film. Further, it can be formed by extruding and coating a molten resin onto the intermediate layer. Alternatively, a sealant film previously formed into a film is used as the sealant layer 11, and the molten resin is extruded between the sealant film and the intermediate layer, and the sealant layer 11 is formed by a sand lamination method or a dry lamination method in which the whole is pressurized. It may be formed.

  Further, the outer surface side resin layer 14 can be formed in the same manner. That is, a melt extrusion coating method, a sand lamination method or a dry lamination method.

  FIG. 2 is a cross-sectional view of a laminate constituting a second embodiment of the liquid paper container of the present invention. The laminated body 20 constituting the liquid paper container of the present embodiment is provided with a paper base material 25 having a concave portion and a void portion 28 formed therein, an outer surface side resin layer 26 and a printing ink layer 27 provided on an outer surface side thereof, On the inner surface side of the paper base material 25, an inner resin layer 24 and a film 22 provided with a transparent vapor-deposited layer 23 are laminated to form an intermediate layer, and a sealant layer 21 is laminated. In addition, a void 28 is formed in a recess provided in the paper base material 25.

  By providing a film 22 provided with a transparent vapor-deposited layer 23 on the intermediate layer, a gas barrier property is imparted to the liquid paper container. As the film 22 provided with the transparent vapor-deposited layer 23, a vapor-deposited film having an inorganic vapor-deposited film is used. Can be used. Examples of the film 22 that is the base material of the vapor deposition film include polyester, polypropylene, and polyamide. Silicon oxide and aluminum oxide can be exemplified as the inorganic substance of the transparent vapor deposition layer 23. As the inner resin layer 24 and the outer resin layer 26, the same resin as the outer resin layer 14 described above can be suitably used. In addition, as the sealant layer 21, the same resin as the above-described sealant layer 11 can be exemplified.

  FIG. 3 is a cross-sectional view of a laminate constituting a third embodiment of the liquid paper container of the present invention. The laminate 30 constituting the liquid paper container of the present embodiment is provided with a printing ink layer 37 and an outer resin layer 38 on the outer surface side of a paper base 36, and a printing ink layer 37 on the inner surface side of the paper base 36. 35, an inner resin layer 34, a metal foil 33 provided with a concave portion, and a film 32 are laminated to form an intermediate layer, and a sealant layer 31 is further laminated. In addition, a void 39 is formed in a recess provided in the metal foil 33.

  By providing the intermediate layer with the metal foil 33, the liquid paper container is provided with gas barrier properties. The film 32 can be the same as the above-described film 22, and the metal foil 33 is preferably an aluminum foil. . Further, as the inner resin layer 34 and the outer resin layer 38, the same resin as the above-described outer resin layer 14 can be preferably used. Further, as the sealant layer 31, the same resin as the above-described sealant layer 11 can be exemplified. In order to provide a concave portion in the metal foil 33, an embossing method can be suitably applied.

  In this embodiment, the gap 39 is provided in the metal foil 33 forming the intermediate layer. However, as in the above-described embodiment, the gap layer 39 exhibits a heat insulating effect, and the temperature rise of the paper base material 36 increases. Is suppressed, the release of water vapor from the paper base material 36 is suppressed, and the occurrence of pinholes and the occurrence of a foaming phenomenon can be suppressed. It can be formed.

  FIG. 4 is a cross-sectional view of a laminate constituting a liquid paper container according to a fourth embodiment of the present invention. The laminated body 40 constituting the liquid paper container of the present embodiment is provided with a paper base material 45 having a concave portion and a void portion 49 formed therein, an outer surface side resin layer 46 and a printing ink layer 47 provided on the outer surface side thereof, On the inner surface side of the paper base material 45, a metal foil 43 provided with a concave portion via an adhesive layer 44 and a film 42 are laminated to form an intermediate layer, and a sealant layer 41 is laminated. In addition, a cavity 48 is formed in a recess provided in the metal foil 43.

  By providing the intermediate layer with the metal foil 43 in the same manner as in the above-described embodiment, the liquid paper container is provided with a gas barrier property. The film 42 may be the same as the film 22 described above. Is preferably an aluminum foil. The voids are formed by the concave portions provided in both the paper base 45 and the metal foil 43, so that a more effective heat insulating effect is obtained, and the release of water vapor from the paper base 45 is more effectively suppressed. In addition, it is possible to suppress the occurrence of pinholes and the occurrence of a foaming phenomenon, and as a result, it is possible to form a liquid paper container in which liquid leakage failure and appearance failure are unlikely to occur.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not construed as being limited to the embodiments described below. In addition, the code | symbol attached to each drawing is used.

<Example 1>
(sample)
-The laminated body 20 of the structure illustrated in FIG. 2 was created as follows.
-Sealant layer 21: Low-density polyethylene resin-Film 22: Polyethylene terephthalate film-Transparent vapor-deposited layer 23: Aluminum oxide vapor-deposited film-Inner resin layer 24: Polyethylene resin-Paper base material 25: Paperboard with depressions formed by embossing -Outer resin layer 26: polyethylene resin-Printing ink layer 27: gravure printing

(Evaluation)
The laminate 20 was heated at 300 ° C. for 1 second using a hot air gun, and the occurrence of a foaming phenomenon was visually checked.
-When no occurrence was observed, it was evaluated as ○, and when it occurred, as x.
-The results are summarized in Table 1.

<Example 2>
-The laminated body 10 of the structure illustrated in FIG. 1 was created as follows.
・ Sealant layer 11: non-stretched polypropylene resin ・ Adhesive layer 12: urethane-based adhesive ・ Paper substrate 13: recessed portion formed by embossing paperboard ・ Outer resin layer 14: polypropylene resin ・ Printing ink layer 15: gravure The printed and prepared laminate was evaluated in the same manner as in Example 1.
-The results are summarized in Table 1.

<Example 3>
-The laminated body 30 of the structure illustrated in FIG. 3 was created as follows.
・ Sealant layer 31: Low density polyethylene resin ・ Film 32: Polyethylene terephthalate film ・ Metal foil 33: Depressed portion formed on aluminum foil by embossing ・ Inner resin layer 34: Polyethylene resin ・ Printing ink layer 35: Gravure printing ・ Paper base Material 36: paperboard / printing ink layer 37: gravure printing / outside resin layer 38: polyethylene resin The prepared laminate was evaluated in the same manner as in Example 1.
-The results are summarized in Table 1.

<Example 4>
-The laminated body 40 of the structure illustrated in FIG. 4 was created as follows.
-Sealant layer 41: Low-density polyethylene resin-Film 42: Polyethylene terephthalate film-Metal foil 43: Forming recesses in aluminum foil by embossing-Adhesive layer 44: Epoxy adhesive-Paper substrate 45: Embossing on paperboard A concave portion was formed in this manner. An outer surface side resin layer 46: a polyethylene terephthalate film and a printing ink layer 47: gravure printing.
-The results are summarized in Table 1.

<Comparative Example 1>
-The laminated body 50 illustrated in FIG. 5 was created with the following configuration.
-Sealant layer 51: low-density polyethylene resin-Film 52: polyethylene terephthalate film-Metal foil 53: aluminum foil-Inner resin layer 54: polyethylene resin-Paper substrate 55: paperboard-Outer resin layer 56: polyethylene resin-printing Ink layer 57: The laminated body 50 produced by gravure printing was evaluated in the same manner as in Example 1.
-The results are summarized in Table 1.

<Comparative Example 2>
-The laminated body 60 illustrated in FIG. 6 was created with the following configuration.
• Sealant layer 61: non-stretched polypropylene resin • Film 62: polyethylene terephthalate film • Transparent vapor-deposited layer 63: aluminum oxide-deposited film • Inner surface resin layer 64: polyethylene resin • Paper substrate 65: paperboard • Outer surface resin layer 66: polypropylene Resin / printing ink layer 67: A gravure-printed and formed laminate was evaluated in the same manner as in Example 1.
-The results are summarized in Table 1.

  The laminates of Comparative Examples 1 and 2 did not occur in the laminates of Examples 1 to 4, in which foaming occurred due to the blowing of heated air. From these results, it was confirmed that in the laminate of the present invention, foaming was unlikely to occur even in the step of sealing the bottom portion and the top portion of the liquid paper container.

10, 20, 30, 40, 50, 60, 80 ... laminated body 11, 21, 31, 41, 51, 61 ... sealant layer 12, 44 ... adhesive layer 13, 25, 36, 45 , 55, 65 ... paper base material 14, 26, 38, 46, 56, 66 ... outer surface side resin layer 15, 27, 35, 37, 47, 57, 67 ... printing ink layer 16, 28 , 39, 48, 49 ... voids 22, 32, 42, 52, 62 ... films 23, 63 ... transparent evaporation layers 24, 34, 54, 64 ... inner surface side resin layers 33, 43 , 53 ... metal foil 70 ... blank

Claims (5)

  A liquid paper container comprising a laminate in which a sealant layer is provided on an inner surface side of a paper base material and a resin layer is provided on an outer surface side, wherein a void is provided between the paper base material and the sealant layer. Liquid paper container.   2. The liquid paper container according to claim 1, wherein the gap is formed in a concave and convex portion provided on an inner surface side of the paper base. 3.   The liquid paper container according to claim 1 or 2, wherein an intermediate layer is provided between the paper base material and the sealant layer.   4. The liquid paper container according to claim 3, wherein the void is formed in a concave and convex portion provided on the paper base side of the intermediate layer. 5.   The liquid paper container according to claim 3, wherein the intermediate layer is a gas barrier layer.

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