EP4635867A1

EP4635867A1 - Gable-top paper container

Info

Publication number: EP4635867A1
Application number: EP23903041.4A
Authority: EP
Inventors: Kouya Nakamura; Atsushi Tanaka; Masayasu ISHII; Tatsuya HORIKOSHI; Haoran MI; Sou Takahashi; Junichi Masuda; Kiyoshi SAITAKA; Katsuyuki Okubo
Original assignee: Nippon Paper Industries Co Ltd; Jujo Paper Co Ltd
Current assignee: Nippon Paper Industries Co Ltd; Jujo Paper Co Ltd
Priority date: 2022-12-13
Filing date: 2023-08-30
Publication date: 2025-10-22
Also published as: JPWO2024127737A1; JP7534561B1; KR20250124101A; WO2024127737A1

Abstract

An object is to provide a gable top type paper container that is easily deformed and hardly returns to the original shape. Provided as a solution is a gable top type paper container formed of a paper base material including base paper and thermoplastic resin layers formed on both front and back surfaces thereof, the paper base material satisfying all of (a) to (c) below,
in which a body panel on an opening side has at least one lateral score line on an upper side thereof, and, when a region between an upper edge of the body panel (a top lateral folding line) and the lateral score line is pushed inward, the gable top type paper container can be deformed so that a space for inserting a finger is widened:
(a) a grammage of the base paper is 230 g/m² or more and 350 g/m² or less;
(b) a yield angle at the lateral score line portion of the paper base material from 0° to 90° is 70° or less; and
(c) a thickness of the paper base material is 280 µm or more and 600 µm or less.

Description

Technical Field

The present invention relates to a gable top type paper container.

Background Art

Conventionally, gable top type paper containers have been used as paper containers for storing liquid contents such as milk and juice.
A gable top type paper container is typically made of a paper base material having thermoplastic resin layers on both front and back surfaces thereof and includes four body panels. Edge portions are joined by a longitudinal-direction seal panel to form a square tubular body portion. A pair of opposing gable roof forming panels having outer top seal panels at the upper parts thereof and a pair of opposing gable wall forming panels having inner top seal panels at the upper parts thereof, one of which is to be opened to be used as a pouring spout, adjoin the upper ends of the body panels. The pair of gable wall forming panels are folded between the pair of gable roof forming panels, and the outer top seal panels and the inner top seal panels are heated, sealed, and tightly closed at a predetermined position to form a gable top (gable-roof)-shaped top portion.
Such a gable top type paper container may be used for drinking by inserting a straw into a pre-processed insertion hole, but in recent years, there has been an increasing need for an environment-conscious container, and there has been a demand for reduction in the use of straws derived from petroleum resources. In order to pour out the contents from such a gable top type paper container without using a straw, a finger is inserted into a space surrounded by the pair of gable roof forming panels, the body panel, and the gable wall forming panel, and the gable wall forming panel is spread to the left and right with the finger to peel apart the heat-sealed opposing surfaces of the outer top seal panels and the inner top seal panels on the opening side. Then, the gable wall forming panel folded between the pair of gable roof forming panels is pulled out and bent outward from a top lateral folding line at the boundary with respect to the body panel adjoining the gable wall forming panel via the top lateral folding line to open a pouring spout. However, when a user has a large hand, when the paper container is small, or when the height of the gable roof-shaped top portion is reduced for the purpose of space saving, the space formed between the body panel and the gable wall forming panel is small. This leads to a problem that it is difficult to put a finger on the gable wall forming panel, and an opening task cannot be easily performed. In addition, there is a problem that a visually impaired person cannot know on which side of the gable roof forming panel an opening part is provided. Furthermore, there has been a case where a user touches the vicinity of the opening side with his/her hand before opening the container, which has led to a concern about hygiene.
As a paper container that solves such a problem, the present applicant has proposed in PTL 1 a paper container in which a lateral score line is provided on the upper side of the gable wall forming panel to be pulled out at the time of opening the paper container and the body panel on the opening side adjoining the gable wall forming panel. When a region between the upper edge of the body panel (the top lateral folding line) and the lateral score line is pushed inward, the paper container can be deformed such that the space into which a finger is inserted is widened.

Citation List

Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 2021-147100

Summary of Invention

Technical Problem

In the paper container described in PTL 1, the space for inserting a finger is widened by deforming the container as designed, and thus, the container can be easily opened. However, because the lateral score line is deformed so as to be mountain-folded on the outside of the container and is not deformed by putting a finger thereon, there have been cases where the container is not bent as designed and where the container is insufficiently bent and returns to the original shape when the finger is released. In addition, there have been cases where the deformation operation is difficult for children, the elderly, people with disabilities in fingers, and the like.
An object of the present invention is to provide a gable top type paper container that is easily deformed and hardly returns to the original shape. Another object of the present invention is to provide a container having an antibacterial layer in the vicinity of an opening part, and a paper container that allows a user to easily distinguish an opening side.

Solution to Problem

The means for solving the problems of the present invention is as follows.

1. A gable top type paper container formed of a paper base material including base paper and thermoplastic resin layers formed on both front and back surfaces thereof, the paper base material satisfying all of (a) to (c) below,
wherein a body panel on an opening side has at least one lateral score line on an upper side thereof, and, when a region between an upper edge of the body panel (a top lateral folding line) and the lateral score line is pushed inward, the gable top type paper container can be deformed so that a space for inserting a finger is widened:
1. (a) a grammage of the base paper is 230 g/m² or more and 350 g/m² or less;
2. (b) a yield angle at a lateral score line portion of the paper base material from 0° to 90° is 70° or less; and
3. (c) a thickness of the paper base material is 280 µm or more and 600 µm or less.
2. The gable top type paper container according to 1, wherein a longitudinal score line is additionally provided in the region.
3. The gable top type paper container according to 1 or 2, wherein a width of the body panel on the opening side is 40 mm or more and 65 mm or less.
4. The gable top type paper container according to any one of 1 to 3, wherein an internal bond strength (internal bond) of the paper base material is 15 N·cm or more and 50 N·cm or less.
5. The gable top type paper container according to any one of 1 to 4, wherein (d) a stiffness of the paper base material in a container longitudinal direction is 3 mN·m or more and 25 mN·m or less.
6. The gable top type paper container according to any one of 1 to 5, wherein an antibacterial layer is provided at least in the region between the upper edge of the body panel (the top lateral folding line) and the lateral score line.
7. The gable top type paper container according to any one of 1 to 6, wherein a point indicator is provided at a central portion of the upper edge of the body panel (the top lateral folding line) or in the vicinity thereof.
8. The gable top type paper container according to 7, wherein the point indicator is formed by embossing. Advantageous Effects of Invention

The gable top type paper container of the present invention has at least one lateral score line on the upper side thereof, and can be deformed so that the space for inserting a finger is widened by pushing the region between the upper edge of the body panel (the top lateral folding line) and the lateral score line inward.
In the gable top type paper container of the present invention, it is easy to push and deform the region between the upper edge of the body panel (the top lateral folding line) and the lateral score line, the space for inserting a finger can be more reliably widened, the deformed portion is less likely to return to the original state, and the deformed shape is easily maintained. In addition, when the drinking spout is pulled out and the lateral score line is bent to the opposite side, the bent portion is less likely to return to the original state and the deformed shape is easily maintained. The gable top type paper container of the present invention having a longitudinal score line in addition to the lateral score line is bent at the score line as designed and is easily deformed, and the space for inserting a finger can be more reliably widened.
The gable top type paper container of the present invention can be opened more easily than conventional gable top type paper containers even by children, the elderly, people with disabilities in fingers, and the like. With the gable top type paper container of the present invention, the space for inserting a finger is widened. Thus, the gable top type paper container can be suitably used as a small gable top type paper container.
The gable top type paper container of the present invention having an antibacterial layer in the vicinity of the opening part is hygienic because the portion to be touched by hand at the time of opening is subjected to antibacterial treatment. With the gable top type paper container of the present invention, which allows a user to easily identify the opening side, the elderly, a visually impaired person, or the like can easily identify the opening side.

Brief Description of Drawings

[Fig. 1] Fig. 1 illustrates a gable top type paper container according to a first embodiment of the present invention.
[Fig. 2] Fig. 2 is a plan view of a carton blank for forming the gable top type paper container according to the first embodiment of the present invention.
[Fig. 3] Fig. 3 illustrates the deformed gable top type paper container according to the first embodiment of the present invention.
[Fig. 4] Fig. 4 is a plan view of a carton blank for forming a gable top type paper container according to a second embodiment of the present invention.
[Fig. 5] Fig. 5 is a plan view of a carton blank for forming a gable top type paper container according to a third embodiment of the present invention.

Description of Embodiments

[Gable Top Type Paper Container]

Fig. 1 illustrates a gable top type paper container (hereinbelow, also referred to as a paper container) according to a first embodiment of the present invention.
The gable top type paper container according to the first embodiment is formed from a carton blank 1 illustrated in Fig. 2. The carton blank 1 includes four body panels 5, 6, 7, and 8 adjoining one another via body longitudinal folding lines 2, 3, and 4. When the paper container is formed, a longitudinal-direction seal panel 10 adjoining the body panel 8 via a body longitudinal folding line 9 and an edge 11 of the body panel 5 are joined, so that the four body panels 5, 6, 7, and 8 form a tubular body portion 12 having a square tubular shape.
A pair of opposing gable roof forming panels 15 and 16, having outer top seal panels 13 and 14 at the upper parts thereof, adjoin the upper ends of the body panels 6 and 8 via top lateral folding lines 17 and 18. A pair of opposing gable wall forming panels 22 and 23, having inner top seal panels 19 and 20 at the upper parts thereof, adjoin the upper ends of the body panels 5 and 7 via top lateral folding lines 24 and 25. One of the gable wall forming panels 22 and 23 is to be opened to be used as a pouring spout. In the first example, the gable wall forming panel 23 is the gable wall forming panel on the opening side to be used as a pouring spout 21.
The gable roof forming panels 15 and 16 are provided with, at positions closer to the gable wall forming panel 23 on the opening side, guide folding lines 26 and 27 for guiding bending of the gable roof forming panels 15 and 16 at the time of opening.
The gable wall forming panels 22 and 23 are provided with inward folding lines 28, 29, 30, and 31 for inwardly folding the gable wall forming panels 22 and 23. Furthermore, substantially triangular surface portions 32 and 33 surrounded by the inward folding lines 28, 29, 30, and 31 and the top lateral folding lines 24 and 25 are formed.
In forming the gable top type paper container, the pair of gable wall forming panels 22 and 23 are folded between the pair of gable roof forming panels 15 and 16, and the outer top seal panels 13 and 14 and the inner top seal panels 19 and 20 are heated, sealed, and tightly closed at a predetermined position. As a result, a gable top (gable roof)-shaped top portion 34 of the gable top type paper container as illustrated in Fig. 1 is formed. In the thus-formed gable top-shaped top portion 34, a space 35 surrounded by the pair of gable roof forming panels 15 and 16, the body panel 7 on the opening side, and the gable wall forming panel 23 on the opening side is formed. A substantially triangular surface portion 33 formed in the gable wall forming panel 23 is positioned on a farther side of the space 35. The space 35 allows a user to put a finger on the gable wall forming panel 23 on the opening side when the gable top type paper container is opened.
Bottom-surface forming panels 40 and 41 adjoin the lower ends of the body panels 5 and 7, and inner panels 42 and 43 adjoin the lower ends of the body panels 6 and 8. By folding the inner panels 42 and 43 inside the bottom-surface forming panels 40 and 41, bonding the contact surfaces together, and sealing the bottom of the tubular body portion 12, a bottom part 44 of the paper container is formed.
A lateral score line 37 is formed on the upper side of the body panel 7 on the opening side. The lateral score line 37 is formed in a downward curved shape connecting intersections 36 of the upper ends of the body longitudinal folding lines 3 and 4 on both sides of the body panel 7 and the ends of a top lateral folding line 25, or the positions in the vicinity of the intersections 36. In the present invention, the shape of the lateral score line 37 is not particularly limited as long as the advantage of the present invention can be obtained, and may be an arc shape, a V shape, a W shape, a shape formed of three or more straight lines and/or curved lines (such as a part of a polygon), or the like, and may be a divided discontinuous line. The ends of the lateral score line need not reach the body longitudinal folding lines 3 and 4 or the top lateral folding line 25 as long as the ends are located near the intersections 36 of the body panel 7 on the opening side.
The lateral score line 37 is used to mountain-fold the body panel 7 at the lateral score line 37. By mountain-folding the body panel 7 at the lateral score line 37, the region between the upper edge of the body panel 7 (the top lateral folding line 25) and the lateral score line 37 is pushed inward. Then, the substantially triangular surface portion 33 is also recessed inward following the movement of the top lateral folding line 25 at the upper edge of the body panel 7. As a result, the space 35 is widened into a shape allowing a user to more easily insert a finger, and the gable top type paper container can be easily opened by inserting a finger into the space 35.
A longitudinal score line 39 is formed on the upper side of and above the body panel 7 on the opening side. In the gable top type paper container of the present invention, the longitudinal score line 39 is optional and may be omitted, but it is preferable to provide the longitudinal score line 39. The longitudinal score line 39 is formed at the center in the width direction of the body panel 7 so as to extend from the lateral score line 37, which is the lower end, to the vicinity of an apex 38 of the substantially triangular surface portion 33 across the top lateral folding line 25. By forming the longitudinal score line 39 in addition to the lateral score line 37, it is possible to guide such that the longitudinal score line 39 is valley-folded when the lateral score line 37 is mountain-folded, that is, the upper edge of the body panel 7 (the top lateral folding line 25) is bent to the inside of the paper container. Thus, the region between the upper edge of the body panel 7 (the top lateral folding line 25) and the lateral score line 37 can be more reliably pushed inward. The shape of the longitudinal score line 39 is not particularly limited as long as the advantage of the present invention can be obtained, and may be linear, curved, a shape formed of two or more straight lines and/or curved lines (such as a part of a polygon), or the like, and may be a divided discontinuous line. In addition, when the longitudinal score line 39 is formed, the longitudinal score line 39 only need to be formed in at least a part of the portion between the lateral score line 37 and the top lateral folding line 25. The lower end of the longitudinal score line 39 need not reach the lateral score line 37 or may be located beyond the lateral score line 37, and the upper end of the longitudinal score line 39 need not reach the top lateral folding line 25 or may be located beyond the top lateral folding line 25 and reach the middle of the substantially triangular surface portion 33. Furthermore, a plurality of longitudinal score lines 39 may be formed. When a plurality of longitudinal score lines 39 are formed, the longitudinal score lines 39 are preferably formed line-symmetrically with respect to the center line in the width direction of the body panel 7.

(Paper Base Material)

The gable top type paper container is formed of a paper base material having a base paper and thermoplastic resin layers formed on both front and back surfaces of the base paper. From the standpoint of the difference in strength of the paper base material between the MD and CD directions (for preventing the occurrence of swelling of the body portion or the like), derived from the orientation directions of pulp fibers, and the ease of forming score lines, it is preferable that the CD direction of the paper base material be the container longitudinal direction and the MD direction be the container lateral direction. In this specification, the container longitudinal direction and the container lateral direction mean the vertical (up-down) direction and the horizontal direction, respectively, when the gable top type paper container of the present invention is erected.
The base paper is obtained by making paper from a paper stock containing pulp, a filler, various additives, and the like. The paper base material of the present invention may have one or two or more functional layers such as an adhesive layer, a filler layer, an ink receiving layer, a water resistant layer, an oil resistant layer, a water vapor barrier layer, and a gas barrier layer between the base paper and the thermoplastic resin layers.
The pulp constituting the base paper is not particularly limited, but preferably contains softwood kraft pulp (NKP) or hardwood kraft pulp (LKP), and more preferably contains softwood kraft pulp. The weight ratio of NKP to LKP (N/L ratio) is preferably in the range of 30/70 to 100/0. The paper container of the present invention is produced by subjecting the paper base material to bending processing or the like. When the weight ratio of LKP is larger than 70, cracks may easily occur at the time of bending. When cracks occur, the appearance may deteriorate, and furthermore, the thermoplastic resin layer may be broken and liquid may ooze out.
Any thermoplastic resin that can be heat-sealed can be used without particular limitation as the thermoplastic resin constituting the thermoplastic resin layer, and examples thereof include low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), polyvinyl acetate (PVAc), polyester resin (PET), ethylene-methacrylic acid copolymer resin (EMAA), ethylene-methyl acrylate copolymer resin (EMA), ethylene-acrylic acid copolymer resin (EAA), ethylene-vinyl acetate copolymer resin (EVA), styrene-acrylic acid ester copolymer resin, polylactic acid resin (PLA), and a copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoate (PHBH).
In the present invention, the paper base material satisfies all of (a) to (c) below:

(a) a grammage of the base paper is 230 g/m² or more and 350 g/m² or less;
(b) a yield angle at the lateral score line portion of the paper base material from 0° to 90° is 70° or less; and
(c) a thickness of the paper base material is 280 µm or more and 600 µm or less.

In the paper base material used in the present invention, (a) the grammage of the base paper is 230 g/m² or more and 350 g/m² or less. When the grammage of the base paper is within this range, the bending property and the shape stability are excellent. The grammage of the paper base material is measured in accordance with JIS P8124:2011. The grammage of the base paper is preferably 240 g/m² or more, more preferably 250 g/m² or more, and is preferably 340 g/m² or less, more preferably 330 g/m² or less.
In the paper base material used in the present invention, (b) the yield angle at the lateral score line portion from 0° to 90° (the bending angle when the maximum bending load value is exhibited when the bending load is measured within the range of 0° to 90° when the paper base material is provided with a score line and is bent about the score line) is 70° or less. Here, the paper is elastically deformed when bent up to the yield angle, but is plastically deformed when bent beyond the yield angle. This is a phenomenon in which the inter-fiber bonds of the paper base material are broken before and after the yield angle, making elastic deformation to return to the original shape impossible. In the shape of the paper container of the present invention after being pushed in with a finger, the bending angle at the lateral score line 37 with respect to the longitudinal direction is approximately 50° to 70°, with the angle being larger at the center portion in the width direction of the body panel 7 (angle θ1 in Fig. 3) and the angle being smaller at the ends in the width direction (angle θ2 in Fig. 3). Hence, in the paper base material having a yield angle of 70° or less, at least the central portion in the width direction of the lateral score line 37 is transferred to plastic deformation when the paper base material is pushed with a finger and deformed. Thus, the lateral score line 37 is easily bent along the score line. Furthermore, in the state in which the lateral score line 37 is bent, the inter-fiber bonds are already broken. Thus, a fold is formed along the lateral score line, and the shape is not easily returned to the original shape. The yield angle of the paper base material is preferably 60° or less, more preferably 55° or less. The lower limit value of the yield angle of the paper base material is preferably 20° or more, more preferably 30° or more. The yield angle of the paper base material can be adjusted with the type of pulp used, the fiber length, the freeness, and the internal bond described below.
In the paper base material used in the present invention, (c) the thickness of the paper base material is 280 µm or more and 600 µm or less. When the thickness exceeds 600 µm, the resistance to bending is high, increasing the force required for bending (making bending difficult). Note that, when bent at the same angle, paper having a larger thickness has a larger strain generated on the mountain-fold side of the paper base material (the mountain-fold side is stretched, generating a strain) and a larger strain generated on the valley-fold side (the valley-fold side is compressed, generating a strain). Thus, a shear force due to the strains in opposite directions strongly acts near the center in the thickness direction of the paper base material, and delamination (interfiber bond failure) is likely to occur inside the paper layer. Hence, there is also an aspect that a fold is easily formed and is not easily returned. When the thickness is less than 280 µm, a fold is less likely to be formed due to small strain, and is likely to return to its original shape after pressing. The thickness of the paper base material is preferably 300 µm or more, more preferably 320 µm or more, and is preferably 560 µm or less, more preferably 520 µm or less.
The paper base material used in the present invention preferably has a maximum bending load value (the value of the bending load at the yield angle, and hereinbelow also referred to as the yield value) measured in (b) of 60 cN or less. When the yield value is 60 cN or less, the paper base material can be deformed with a small force. Thus, the longitudinal score line 39 provided on the upper side of and above the body panel 7 on the opening side can be easily pushed inward. The yield value is more preferably 55 cN or less, and more preferably 50 cN or less. Furthermore, if the yield value is too low, when the longitudinal score line 39 provided on the upper side of and above the body panel 7 on the opening side is pushed inward, the portion other than the score line is bent, and the expected space 35 may not be obtained. Hence, the yield value is preferably equal to or higher than 20 cN, and more preferably equal to or higher than 25 cN.
The yield angle and yield value of the paper base material can be adjusted with the grammage of the base paper and the paper base material, the type of pulp, the freeness, the internal bond strength, the score height (the depth of the score line), and the like. For example, the shorter the fiber length of the pulp, the smaller the yield angle and the yield value, making bending easy. However, if the proportion of short fibers is too high, score lines tend to crack. Hence, the base paper containing 30% by weight or more and 80% by weight or less of softwood pulp in the total pulp makes it easy to achieve the desired yield angle of the present invention. In addition, because the bonding between pulp fibers is stronger when the freeness of pulp is lower, the displacement between the fibers is less likely to occur at the time of bending. Thus, the yield angle tends to increase and the yield value tends to increase. Meanwhile, if the freeness is too high, the bonding between pulp fibers is weak, and it is difficult to obtain stiffness at the same grammage. Hence, by making the freeness of pulp 400 ml or more and 650 ml or less (CSF), it is easy to achieve the desired yield angle of the present invention.
The internal bond strength (internal bond) of the paper base material used in the present invention is preferably from 15 N·cm or more and 50 N·cm or less. When the internal bond strength of the paper base material is 15 N·cm or more, the stiffness of the paper base material is high, and thus, a fold is easily made along the score line when the score line is bent. When the internal bond strength is 50 N·cm or less, the inside of the paper layer at the bent portion is easily broken. As a result, a fold is easily formed (forming failure is less likely to occur), and, when the paper base material is bent to the opposite side again, the paper base material is easily bent along the score line. The internal bond strength of the paper base material is more preferably 18 N·cm or more, and even more preferably 20 N·cm or more, and is more preferably 45 N·cm or less, and even more preferably 40 N·cm or less. The internal bond strength of the paper base material can be measured in accordance with "Paper and board - Determination of internal bond strength - Part 2: Internal bond tester method" specified in J. TAPPI No. 18-2:2000.
The internal bond strength of the paper base material can be adjusted by adjusting the pulp raw material used for the paper base material. The pulp raw material of the base paper of the present invention preferably contains softwood kraft pulp (NKP) in an amount of 30% by weight or more in the total raw material pulp. The internal bond strength of the paper base material can also be adjusted with the degree of beating of raw material pulp fibers of the paper base material, and it is desirable that the freeness of the disintegrated material pulp be 400 ml or more and 650 ml or less (CSF). The degree of beating of pulp fibers can be expressed by Canadian Standard Freeness (CSF) defined in JIS P8121-2:2012.
The paper base material used in the present invention in a state in which no score line is formed preferably has (d) a stiffness in the container longitudinal direction of 3 mN·m or more and 25 mN·m or less. If the stiffness is 25 mN·m or less, the paper container can be deformed with a smaller force, and is easily bent along the score line. If the stiffness is less than 3 mN·m, only the portion pressed by the finger and the vicinity thereof may be depressed, and the paper container may not be bent along the score line, making the size and shape of the space 35 unstable. The stiffness is more preferably 4 mN·m or more, and even more preferably 5 mN·m or more, and is more preferably 20 mN·m or less, and even more preferably 15 mN·m or less.

(Antibacterial Layer)

Fig. 4 illustrates a carton blank 1 for forming a paper container having an antibacterial layer 45 according to a second embodiment. The same reference numerals denote the same components as those of the carton blank illustrated in Fig. 1.
The paper container of the present invention is deformed such that the body panel 7 is mountain-folded at the lateral score line 37 by pushing the body panel 7 with a finger, and the region between the upper edge of the body panel 7 (top lateral folding line 25) and the paper container is bent at the lateral score line 37 inward. However, this region is a portion to be touched with a finger, and bacteria and the like may be adhered. In addition, because this region is a portion close to the spout, there is a possibility that the adhered bacteria may enter the mouth when a user drinks the beverage directly. In order to prevent these problems, it is hygienic to provide the antibacterial layer 45 at least in the region between the upper edge of the body panel 8 (top lateral folding line 25) and the lateral score line 37.
The antibacterial layer 45 is provided by printing a mixed liquid obtained by mixing an antibacterial agent with an adhesive binder on the outer surface of the gable wall forming panel 23, spray coating, coating, or forming a laminated layer using a masterbatched antibacterial agent.
Known antibacterial agents can be used as the antibacterial agent, and metal-based antibacterial agents, such as silver-based inorganic antibacterial agents, copper-based inorganic antibacterial agents, and zinc-based inorganic antibacterial agents, are preferable because of their excellent antibacterial performance. Among the metal-based antibacterial agents, silver-based inorganic antibacterial agents are particularly preferable because of their high food safety. More specifically, an antibacterial varnish, such as "Rab coat W-101" and "Rab coat U-6501" manufactured by SAKATA INX CORPORATION, may be used. The antibacterial varnish may be a water-based ink or a UV-curable ink. The adhesive binder to be used is also a known adhesive binder.
The antibacterial layer 45 only needs to be provided in the region between the upper edge of the body panel 7 (the top lateral folding line 25) and the lateral score line 37, and is preferably provided so as to extend on at least one of the gable wall forming panel 23 and the body panel 7, and is more preferably provided on the gable wall forming panel 23, which is closer to the spout. Although the antibacterial layer may be provided on the entire surface of the body panel 7, providing the antibacterial layer on the surface above the lowest point of the lateral score line 37 suppresses the growth of bacteria in the spout portion and saves costs.

(Visual Effect and Tactile Effect)

Fig. 5 illustrates a carton blank 1 for forming a paper container according to a third embodiment, having a point indicator 46 in the vicinity of the intersection of the top lateral folding line 25 and the longitudinal score line 39. The same reference numerals denote the same components as those of the carton blank illustrated in Fig. 1.
The point indicator 46 is a mark indicating a portion (push point) to be pushed in order to deform the paper container of the present invention into a desired shape. By pushing the point indicator 46, the paper container of the present invention can be bent along the score line and reliably deformed into a desired shape. The point indicator 46 is not particularly limited as long as the presence thereof can be recognized, and may be formed by embossing or printing. Embossing is preferable because even a person with impaired vision can operate the point indicator 46.
The point indicator is provided so as to straddle the substantially triangular surface portion 33 and the body panel 7, or in either of the substantially triangular surface portion 33 and the body panel 7, at the center part of the top lateral folding line 25 or in the vicinity thereof. In the third embodiment illustrated in Fig. 5, the point indicator 46 is provided at the center of the top lateral folding line 25 so as to straddle the substantially triangular surface portion 33 and the body panel 7.
The shape of the point indicator 46 is not particularly limited, and for example, the use of the point indicator 46 as a design provides the paper container with a design effect. It is also effective to add a tactile effect, such as braille, to indicate the portion to be opened or the portion to be pushed in, thus providing universal design for a visually impaired person or the like.
The gable top type paper container of the present invention can be used as a container for storing a liquid such as: a beverage such as milk or juice; an edible liquid including a seasoning such as soy sauce or vinegar, and oil; or a non-beverage liquid such as shampoo, conditioner, kitchen detergent, or laundry detergent. The gable top type paper container of the present invention allows a user to easily widen the space for inserting a finger, and thus can be suitably used for a small paper container having a small space for inserting a finger before deformation, and can be suitably used for a gable top type paper container in which the width of the body panel on the opening side is 40 mm or more and 65 mm or less.

EXAMPLES

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, the parts and percentages in the examples are parts by weight and percentages by weight.

[EXAMPLE 1]

A double-sided polyethylene coated base paper (standard grammage value 313 g/m²), manufactured by Nippon Dynawave Packaging Co., was used as the paper base material. The thickness of the polyethylene coating film was 16 g/m² on the front surface (surface exposed to the outside, non-glossy surface) and 26 g/m² on the back surface (surface facing the inside of the container, non-glossy surface).
In the preparation of gables for evaluation described below, paper base materials were used so that the container longitudinal direction was the CD direction.

[EXAMPLE 2]

A double-sided polyethylene coated base paper (standard grammage value 285 g/m²), manufactured by Nippon Dynawave Packaging Co., was used as the paper base material. The thickness of the polyethylene coating film was 14 g/m² on the front surface (surface exposed to the outside, non-glossy surface) and 24 g/m² on the back surface (surface facing the inside of the container, glossy surface).
In the preparation of gables for evaluation described below, paper base materials were used so that the container longitudinal direction was the CD direction.

[EXAMPLE 3]

A double-sided polyethylene coated base paper (standard grammage value 256 g/m²), manufactured by Nippon Dynawave Packaging Co., was used as the paper base material. The thickness of the polyethylene coating film was 15 g/m² on the front surface (surface exposed to the outside, non-glossy surface) and 24 g/m² on the back surface (surface facing the inside of the container, non-glossy surface).
In the preparation of gables for evaluation described below, paper base materials were used so that the container longitudinal direction was the CD direction.

[COMPARATIVE EXAMPLE 1]

A double-sided polyethylene coated base paper (standard grammage value 420 g/m²), manufactured by Nippon Dynawave Packaging Co., was used as the paper base material. The thickness of the polyethylene coating film was 16 g/m² on the front surface (surface exposed to the outside, non-glossy surface) and 26 g/m² on the back surface (surface facing the inside of the container, non-glossy surface).
In the preparation of gables for evaluation described below, paper base materials were used so that the container longitudinal direction was the CD direction.

[COMPARATIVE EXAMPLE 2]

The same paper base material as in Comparative Example 1 was used except that the paper base material was used so that the container longitudinal direction was the MD direction in the preparation of the gable for evaluation described below.

[COMPARATIVE EXAMPLE 3]

The same paper base material as in Example 3 was used except that the paper base material was used so that the container longitudinal direction was the MD direction in the preparation of the gable for evaluation described below.

[COMPARATIVE EXAMPLE 4]

A base paper (manufactured by WestRock Company, standard grammage value 215 g/m²) having both sides coated with polyethylene was used as the paper base material. The thickness of the polyethylene coating film was 16 g/m² on the front surface (surface exposed to the outside, non-glossy surface) and 26 g/m² on the back surface (surface facing the inside of the container, non-glossy surface).
In the preparation of gables for evaluation described below, paper base materials were used so that the container longitudinal direction was the CD direction.
The obtained paper base material was evaluated as follows. The results are shown in Table 1.

(Evaluation Method)

Yield Angle and Yield Value

Score lines were formed in the paper base materials, and gable top type paper containers having the shape illustrated in Fig. 1 were formed. In these paper containers, the size of the body panels on the opening side was 6 cm wide and 7 cm high.
Samples having a rectangular shape of 20 mm width and 70 mm long and having score lines extending in the width direction were cut out from the center in the width direction of the body panels on the opening side in which the score lines were formed. Using a bending stiffness measuring machine BST-α (ASAHISOUKEN CORPORATION), the samples were bent at a right angle in the longitudinal direction so as to be bent along the score line from 0° (state before bending) to 90°, and the bending loads were measured.
The measured angles were plotted on the horizontal axis and the bending loads (cN) were plotted on the vertical axis, and the angle showing the maximum value was regarded as the yield angle and the maximum value was regarded as the yield value. The measurement was performed three times, and the average values are shown in Table 1. For the samples having a yield angle higher than 70°, the values of the bending loads at 70° are shown in the fields of the yield value in Table 1.

Internal Bond Strength (Internal Bond)

According to the internal bond tester method as specified in JAPAN TAPPI No. 18-2:2000 (Paper and Paper Board-Internal Bond Strength Test Method-Part 2), one surface of the sample was attached to a fixing stand with a double-sided tape, an L-shaped metal fitting was attached to the opposite surface, and this was pressure-bonded for a certain period of time. Then, an impact was applied to the L-shaped metal fitting with a hammer, and the amount of work when the sample was peeled off together with the L-shaped metal fitting was measured.

Stiffness in Container Longitudinal Direction

The bending moment in the container longitudinal direction was measured according to the bending resistance measuring method specified in JIS P8125-2:2017 (Paper and board-Determination of bending resistance-Part 2: Taber-type tester).

Freeness of Disintegrated Base Paper

The paper base materials used in Examples and Comparative Examples were immersed in water for 12 hours. Then, the paper was rubbed with fingers in both MD and CD directions to peel off the laminated layers on the surfaces in the water to prepare samples. Samples having a bone dry pulp weight of 24 g were torn by hand into about 2 cm squares, and water was added thereto until a weight of 1200 g was reached (pulp concentration was 2%).
These were disintegrated by using a standard disintegrator according to the pulp disintegration method specified in JIS P8220-1 (2012), and the Canadian standard freeness (CSF) was measured according to the method specified in JIS P8121-2 (2012).

Ease of Pushing

Paper base materials were provided with score lines and formed into the shape illustrated in Fig. 1.
The push point, which is the intersection of the top lateral folding line and the longitudinal score line, was pushed at an angle of 45° (until the moment when the paper starts to be bent) with a silicon finger (contact area: 10 × 14 mm), and the force (N) applied to the silicon finger at that time was measured. The evaluation was performed according to the following criteria:

○: The force applied was 16 N or less;
×: The force applied was greater than 16 N.

Return Resistance

Paper base materials were provided with score lines and formed into the shape illustrated in Fig. 1.
The push point was pushed at an angle of 45° (until the paper base material was bent at the lateral score line at 70° at the maximum angle portion) with a silicon finger (contact area: 10 × 14 mm), and the pushed portion after the finger was released was visually observed and evaluated according to the following criteria:

○: The paper base material was kept bent at the lateral score line and did not return to the original state;
Δ: The bent state was kept immediately after the finger was released, but gradually returned to the original state;
×: The pressed portion returned to the original shape immediately after the finger was released.

Ease of Opening (Shape Stability)

Gable top type paper containers having the same shape as those used for the measurement of the yield angle and the yield value were formed.
The push point was pushed at an angle of 45° (until the lateral score line was bent at 70° at the maximum angle portion) with a silicon finger (contact area: 10 × 14 mm). Then, fingers were inserted into the space surrounded by the gable roof forming panels, the body panel on the opening side, and the gable wall forming panel, the fingers were put on the gable wall forming panel to spread the gable wall forming panel to the left and right to peel apart the heat-sealed opposing surfaces of the top seal panel from each other, and the folded gable wall forming panel was pulled out.
The state of the pouring spout when pulled out was visually observed.

1: The pouring spout was appropriately bent along the score lines, and could be opened as expected;
2: The portion pulled out was not rigid and was bent in the shapes of the fingers, and wrinkled;
3: The portion pulled out was bent at a portion other than the longitudinal score line.

[Table 1]

			EXAMPLE 1	EXAMPLE 2	EXAMPLE 3	COMPARATIVE EXAMPLE 1	COMPARATIVE EXAMPLE 2	COMPARATIVE EXAMPLE 3	COMPARATIVE EXAMPLE 4
GRAMMAGE	PAPER BASE MATERIAL	g/m²	360	327	303	487	487	303	257
GRAMMAGE	(a) BASE PAPER	g/m²	316	288	261	434	434	261	215
PAPER THICKNESS	(c) PAPER BASE MATERIAL	µm	481	447	397	642	642	397	310
PAPER THICKNESS	BASE PAPER	µm	433	406	351	584	584	351	265
(b) YIELD ANGLE		∘	40.7	44.4	53.9	GREATER THAN 90	GREATER THAN 90	GREATER THAN 90	87.8
YIELD VALUE (IF GREATER THAN 70°, VALUE AT 70°)		cN	44.1	38.0	31.1	25.1	73.5	34.6	56.8
INTERNAL BOND STRENGTH		N·cm	25.8	33.7	25.2	24.5	24.5	26.7	14.0
(d) STIFFNESS IN CONTAINER LONGITUDINAL DIRECTION		mN·m	10.8	7.9	5.2	23.3	56.9	14.8	2.3
SCORE HEIGHT		µm	140	140	140	140	140	140	140
SCORE WIDTH		µm	722	673	670	722	722	670	1200
FREENESS OF DISINTEGRATED BASE PAPER		mICSF	575	540	525	490	490	525	630
EASE OF PUSHING			○	○	○	x	x	x	○
RETURN RESISTANCE			○	○	○	○	x	○	x
EASE OF OPENING (SHAPE STABILITY)			1	1	1	1	3	1	2

Reference Signs List

1 Carton blank
2, 3, 4 Body longitudinal folding line
5, 6, 7, 8 Body panel
9 Body longitudinal folding line
10 Longitudinal-direction seal panel
11 Edge
12 Tubular body portion
13, 14 Outer top seal panel
15, 16 Gable roof forming panel
17, 18 Top lateral folding line
19, 20 Inner top seal panel
21 Pouring Spout
22, 23 Gable wall forming panel
24, 25 Top lateral folding line
26, 27 Guide folding line
28, 29, 30, 31 Inward folding line
32, 33 Substantially triangular surface portion
34 Gable top-shaped top portion
35 Space
36 Intersection
37 Lateral score line
38 Apex
39 Longitudinal score line
40, 41 Bottom-surface forming panel
42, 43 Inner panel
44 Bottom part of paper container
45 Antibacterial layer
46 Point indicator

Claims

A gable top type paper container formed of a paper base material including base paper and thermoplastic resin layers formed on both front and back surfaces of the base paper, the paper base material satisfying all of (a) to (c) below,
wherein a body panel on an opening side has at least one lateral score line on an upper side thereof, and, when a region between an upper edge of the body panel (a top lateral folding line) and the lateral score line is pushed inward, the gable top type paper container can be deformed so that a space for inserting a finger is widened:
(a) a grammage of the base paper is 230 g/m² or more and 350 g/m² or less;

(b) a yield angle at a lateral score line portion of the paper base material from 0° to 90° is 70° or less; and

(c) a thickness of the paper base material is 280 µm or more and 600 µm or less.
The gable top type paper container according to Claim 1, wherein a longitudinal score line is additionally provided in the region.
The gable top type paper container according to Claim 1 or 2, wherein a width of the body panel on the opening side is 40 mm or more and 65 mm or less.
The gable top type paper container according to Claim 1 or 2, wherein an internal bond strength (internal bond) of the paper base material is 15 N·cm or more and 50 N·cm or less.
The gable top type paper container according to Claim 1 or 2, wherein (d) a stiffness of the paper base material in a container longitudinal direction is 3 mN·m or more and 25 mN·m or less.
The gable top type paper container according to Claim 1 or 2, wherein an antibacterial layer is provided at least in the region between the upper edge of the body panel (the top lateral folding line) and the lateral score line.
The gable top type paper container according to Claim 1 or 2, wherein a point indicator is provided at a central portion of the upper edge of the body panel (the top lateral folding line) or in the vicinity thereof.
The gable top type paper container according to Claim 7, wherein the point indicator is formed by embossing.