Container and container manufacturing method

Abstract

A container includes a cylindrical barrel part, a flange part, and a bottom part. The cylindrical barrel part has a side seam part at a side surface thereof, the side seam part being formed by bonding a paper material coated with a thermoplastic resin. The flange part is formed of the paper material rolled at one edge of the barrel part, to which a lid material is bonded by heat sealing. The bottom part is formed at another edge of the barrel part. The flange part has a step part with a predetermined height and a predetermined width at an outer peripheral edge of an upper surface thereof.

Description

Technical Field

[0001] The present invention relates to a container for food and beverage and a manufacturing method therefor.Background Art

[0002] Conventionally, those fabricated by hermetically sealing an opening edge of a container including a barrel part with a side seam part (bonding part) and a bottom part attached to the inside of the barrel part, which are made of sheet-like materials, with a film-like lid material, are widely used as containers (paper cups) for food and beverage.

[0003] The opening edge of the container is provided with a flange part extending outward from the container. After the container is filled with contents such as beverage, the lid material is bonded to the flange part through a heat sealing, for example.

[0004] Patent Literature 1 below has described that such a flange part (mouth roll) is formed to have a circular (curl-shaped) cross-section.

[0005] Patent Literature 2 below has described that such a flange part (cup rim) is vertically pressed to be flat.Citation ListPatent Literature

[0006] Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2008-507458 Patent Literature 2: Japanese Patent Application Laid-open No. 2004-042987 Disclosure of InventionTechnical Problem

[0007] However, in a case where the flange part is curl-shaped as described in Patent Literature 1 above, the flange part may be deformed at the time of sealing with the lid material, changing opening outer diameter dimensions. As a result, the fitting property of a lid (over-cap) fitted to the flange part is deteriorated.

[0008] Moreover, in a case where the flange part is curl-shaped as described in Patent Literature 1 above and in a case where the flange part has a pressed flat shape as described in Patent Literature 2 above, the flange part may be deformed at the time of opening the lid material. As a result, it is difficult to stably open the lid material and the fitting property of the lid is deteriorated.

[0009] In view of the above-mentioned circumstances, it is an object of the present invention to provide a container whose flange part can be suppressed from being deformed at the time of sealing with a lid material and at the time of opening the lid material without changing sealing conditions of the lid material and to provide a container manufacturing method.Solution to Problem

[0010] In order to accomplish the above-mentioned object, a container according to an embodiment of the present invention includes a cylindrical barrel part, a flange part, and a bottom part. The cylindrical barrel part has a side seam part at a side surface thereof, the side seam part being formed by bonding a paper material coated with a thermoplastic resin. The flange part is formed of the paper material rolled at one edge of the barrel part, to which a lid material is bonded by heat sealing. The bottom part is formed at another edge of the barrel part. The flange part has a step part with a predetermined height and a predetermined width at an outer peripheral edge of an upper surface thereof.

[0011] With this configuration, due to the presence of the step part in the outer peripheral edge of the upper surface of the flange part, a seal head comes into contact only with the inside of the flange part without coming into contact with the step part at the time of sealing with the lid material. As a result, the deformation of the flange part can be prevented. Moreover, at the time of opening the lid material, a working point of an opening force with respect to a fulcrum point (boundary between the barrel part and the flange part) is located inside (starting point of the step part) with respect to the outer peripheral edge of the flange part. Therefore, the moment of the force decreases, which can suppress the deformation of the flange part.

[0012] The predetermined height may be equal to or larger than a half of a thickness of the paper material.

[0013] Accordingly, it is possible to secure a minimum height for the step part and prevent the step part from being sealed at the time of sealing with the lid material.

[0014] Assuming that a boundary between the barrel part and the flange part is a fulcrum point of force for opening the lid material and a starting point of the step part is a working point of the force , the predetermined width may be set to be such a length that a moment of the force is smaller than 60 N*mm.

[0015] Accordingly, due to setting the moment of the force for opening to be smaller than 60 N*mm, the deformation of the flange part at the time of opening can be suppressed while keeping the sealing strength. If the moment of the force is equal to or larger than 60 N*nm, the flange part may be deformed at the time of opening. It should be noted that such a width of the step part is substantially equal to or larger than twice of the thickness of the paper material.

[0016] The flange part may include a double-layered part which is located in a lower portion of the step part, where two portions of the paper material overlap each other in a cross-sectional view in a radial direction of the barrel part, and a triple-layered part which is located on an inner peripheral side with respect to the double-layered part, where three portions of the paper material overlap one another in the cross-sectional view. In this case, the double-layered part may have a single bonding part that bonds two pieces of paper, and the triple-layered part may have two bonding parts that adhere three pieces of paper.

[0017] Accordingly, it is possible to increase the strength of the step part in the double-layered part and to perform sealing in the triple-layered part with stably high strength at the time of sealing with the lid material.

[0018] The flange part may have a space between the bonding parts of the double-layered part and the bonding parts of the triple-layered part.

[0019] Accordingly, due to the space formed between the triple-layered part of the lid material with higher sealing strength and the double-layered part of the lid material with lower sealing strength, a portion whose sealing strength is lower than the triple-layered part and higher than the double-layered part is formed and the sealing strength can stepwisely increase from the outer peripheral side to the inner peripheral side of the flange part, and therefore it is possible to improve the opening property by gradually increasing the moment of force for opening the lid material from the outer peripheral side to the inner peripheral side .

[0020] A container manufacturing method according to another embodiment of the present invention includes: forming a cylindrical barrel part having a side seam part at a side surface by bonding a paper material coated with a thermoplastic resin; forming a bottom part at one edge of the barrel part; forming a curl-shaped flange part by rolling another edge of the barrel part; and forming a step part with a predetermined height and a predetermined width by stamping an outer peripheral edge of the flange part.

[0021] Accordingly, only adding the stamping step for the outer peripheral edge to the conventional manufacturing process for the curl part enables manufacture of a container whose flange part can be suppressed from being deformed at the time of sealing with a lid material and at the time of opening the lid material.Advantageous Effects of Invention

[0022] As described above, in accordance with the present invention, it is possible to provide a container whose flange part can be suppressed from being deformed at the time of sealing with a lid material and at the time of opening the lid material without changing sealing conditions of the lid material and to provide a container manufacturing method. It should be understood that this effect does not limit the present invention.Brief Description of Drawings

[0023] [Fig. 1] A view showing the front outer appearance of a paper cup according to an embodiment of the present invention. [Fig. 2] An enlarged cross-sectional view of a flange part in Fig. 1. [Fig. 3] A diagram showing results of examination for selecting a height of a step part of the flange part. [Fig. 4] A diagram showing experimental results for selecting a width of the step part of the flange part. [Fig. 5] A diagram showing experimental results about deformation and changes in opening outer diameter dimensions at the time of sealing with the flange part in comparison with a conventional rounded curl-shaped flange part. [Fig. 6] A flowchart showing a manufacturing process for the paper cup. Mode(s) for Carrying Out the Invention

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.[Outer Appearance of Paper Cup]

[0025] Fig. 1 is a diagram showing the front outer appearance of a paper cup as a container according to an embodiment of the present invention. The figure is partially shown in a cross-section.

[0026] As shown in the figure, a paper cup 100 according to the present embodiment includes a barrel part 1 and a bottom part 2.

[0027] The barrel part 1 is fabricated by covering (laminating) a paper material (paper sheet) as a raw material with a thermoplastic resin, e.g., polyethylene, polypropylene, or polyester, punching it into a fan-shaped blank, wrapping it around a cylindrical die, and bonding side edge parts overlapping each other. As a result of the bonding of the side edge parts, the barrel part 2 has a side seam part 4 vertically formed at a side surface thereof.

[0028] The bottom part 2 is fabricated by choking a circular bottom paper punched out from a paper material similar to the paper material of the barrel part 1 and bonding the circular bottom paper to an inner bottom edge of the barrel part 1 simultaneously with bonding of the barrel part 1.

[0029] The bottom edge of the barrel part 1 to which the bottom part 2 is bonded is press-fitted with its paper material folded inward. Moreover, a flange part 3 where the paper material is rolled outward is formed at a top edge of the barrel part 1 and the barrel part 1 is opened at the flange part 3.

[0030] After the paper cup 100 is filled with contents such as beverage and ice cubes, the paper cup 100 is hermetically sealed by bonding a lid material such as a polyethylene film to the flange part 3 by heat sealing, for example.

[0031] Each of the paper materials as the raw materials of the barrel part 1 and the bottom part 2 have a plurality of layers, for example. A synthetic resin layer, a foam layer, a metal layer, an inorganic vapor deposition film, and the like in addition to a laminate layer made of the thermoplastic resin may be stacked on the paper material.

[0032] In order to prevent hard objects such as ice cubes employed as contents from breaking the paper cup 100, a resin film such as polyethylene terephthalate may be further stacked on the barrel part 1 and the bottom part 2.[Shape of Flange Part]

[0033] Fig. 2 is an enlarged cross-sectional view of the flange part 3 ("E" part in Fig. 1).

[0034] As shown in the figure, the flange part 3 includes a sealing surface 31 to which the lid material is bonded, a rolled part 32 in which the barrel part 1 is rolled, and a step part 33.

[0035] A width A of the flange part 3 is 2 to 5 mm and a thickness B of the flange part 3 is substantially equal to three times a thickness T of the paper material.

[0036] The step part 33 is formed at an outer peripheral edge of an upper surface of the flange part 3. As it will be described later, the step part 33 is formed by stamping an outer peripheral edge of a rounded curl-shaped flange part.

[0037] Due to the presence of the step part 33, a seal head comes into contact only with the inside (sealing surface 31) of the flange part 3 without coming into contact with the step part 33 at the time of sealing with the lid material. As a result, the deformation of the flange part 3 can be prevented. Moreover, at the time of opening the lid material, a working point W of an opening force (arrow in the figure) with respect to a fulcrum point F (boundary between the barrel part 1 and the flange part 3) is located inside (starting point of the step part 33) with respect to the outer peripheral edge of the flange part 3. Therefore, the moment of the force decreases, which can suppress the deformation of the flange part 3.

[0038] Moreover, the flange part 3 includes a double-layered part 34 and a triple-layered part 35. The double-layered part 34 is located in a lower portion of the step part 33. In the double-layered part 34, two portions of the paper material overlap each other in a cross-sectional view of the barrel part 1 in a radial direction (X direction). The triple-layered part 35 is located on the inner peripheral side with respect to the double-layered part 34. In the triple-layered part 35, three portions of the paper material overlap one another in the cross-sectional view. That is, the step part 33 is formed by pressing the portion of the rounded curl-shaped flange part where the two portions of the paper material overlap each other at the outer peripheral edge while leaving the portion of the rounded curl-shaped flange part where the three portions of the paper material overlap one another on the inner peripheral side as it is.

[0039] The double-layered part 34 has a single bonding part 34a bonding such two pieces of paper by fusion, for example. The triple-layered part 35 has two bonding parts 35a and 35b bonding such three pieces of paper by fusion, for example. Accordingly, it is possible to increase the strength of the step part 33 in the double-layered part 34 and to perform sealing in the triple-layered part 35 with stably high strength at the time of sealing with the lid material.

[0040] Moreover, a space S is formed between the bonding part 34a of the double-layered part 34 and the bonding parts 35a and 35b of the triple-layered part 35. Accordingly, due to the space S formed between the triple-layered part 35 of the lid material with higher sealing strength and the double-layered part 34 of the lid material with lower sealing strength, a portion whose sealing strength is lower than the triple-layered part 35 and higher than the double-layered part 34 is formed. Therefore, since the sealing strength can stepwisely increase from the outer peripheral side to the inner peripheral side of the flange part 3, it is possible to improve the opening property by gradually increasing the moment of the force from the outer peripheral side to the inner peripheral side at the time of opening the lid material.

[0041] Here, a height D of the step part 33 (distance between the sealing surface 31 and a bottom surface of the step part 33) is set to be equal to or larger than a half of the thickness T of the paper material.

[0042] Fig. 3 is a table showing results of examination for selecting the height D of the step part 33. As shown in the figure, the inventors of the present invention calculated a thickness of the paper sheet compressed at the time of stamping four types of paper sheets (paper sheets A to D) with different density.

[0043] The paper sheet of the paper cup 100 has density of 0.75 g / cm 3< or more and density specific to cellulose that is a main component of the paper sheet is 1.5 g / cm 3< on the basis of the actual usage. Therefore, the compression ratio is 2 or less.

[0044] As described above, the step part 33 is formed by pressing the portion (corresponding to the double-layered part 34) of the curl-shaped flange part where the two portions of the paper sheet overlap each other at the outer peripheral edge while leaving the portion (corresponding to the triple-layered part 35) of the curl-shaped flange part where the three portions of the paper sheet overlap one another on the inner peripheral side as it is. Therefore, as shown in the figure, a difference between the thickness of three pieces of paper compressed and the thickness of two pieces of paper compressed (equivalent to the height of the step part 33) is 0.15 mm (half of the thickness T of the paper sheet). Therefore, the height D of the step part 33 is desirably set to T / 2 or more.

[0045] Moreover, assuming that the boundary between the barrel part 1 and the flange part 3 is the fulcrum point F of force for opening the lid material and the starting point of the step part 33 is the working point W of the force, a width C of the step part 33 (distance between a boundary between the sealing surface 31 and the step part 33 and the outer peripheral edge of the flange part 3) is set to be such a length that the working point W is positioned in vicinity of substantially the center of the flange part 3 in the direction of the width A (X direction).

[0046] Fig. 4 is a table showing experimental results for selecting the width C of the step part. As shown in the figure, the inventors of the present invention changed a distance between the fulcrum point F and the working point W (width of the flange part 3 - width of the step part 33) and measured peel strength and moment of the force at the time of opening the sealed lid material.

[0047] The thickness of the paper sheet used in experiment was set to about 0.30 mm and the width of the flange part 3 was set to 3.0 mm. Moreover, conditions at the time of sealing with the lid material were set so that a sealing time is 1.2 sec, a sealing temperature is 130 °C, and a sealing pressure is 130 kgf.

[0048] As shown in the figure, it was possible to maintain peel strength of 15N to 20N and retain the opening function by setting the distance between the fulcrum point F and the working point W to be smaller than 3.0 mm and setting the moment of the force for opening to be smaller than 60 N*mm. On the other hand, in a case of a width whose peel strength is equal to or larger than 20N (the moment of the force is equal to or larger than 60 N*mm), the flange part 3 was deformed (lifted up) and the opening was impossible in some cases.

[0049] Therefore, the width C of the step part 33 is favorably set to be such a length that the moment of the force applied to the working point W at the time of opening the lid material is smaller than 60 N*mm. The width C is substantially larger than twice of the thickness T of the paper material.

[0050] Fig. 5 is a table showing experimental results as to deformation and changes in opening outer diameter dimensions at the time of sealing the configured flange part 3 as described above in comparison with the conventional rounded curl-shaped flange part.

[0051] As shown in the figure, regarding the conventional rounded curl-shaped flange part and the flange part 3 according to the present embodiment, opening outer diameter dimensions in the X direction (outer diameter not including the side seam part 4) and the Z direction (outer diameter including the side seam part 4) (Fig. 1) before and after the lid material is sealed were measured and its average value, maximum value, minimum value, range (difference between the maximum value and the minimum value), and standard deviation were calculated.

[0052] As to the conventional rounded curl-shaped flange part, dimension changes were large, specifically, +0.7 mm in the X direction and +0.9 mm in the Z direction as average values. Meanwhile, as to the flange part 3 according to the present embodiment, dimension changes were extremely small, specifically, -0.1 mm in the X direction and -0.1 mm in the Z direction as average values.

[0053] Therefore, it was demonstrated that the step part 33 according to the present embodiment can prevent deformation and a port outer shape dimension change at the time of sealing.[Manufacturing Method for Paper Cup]

[0054] Next, a manufacturing method for the paper cup 100 will be described. Fig. 6 is a flowchart showing a flow of a manufacturing process for the paper cup 100.

[0055] As shown in the figure, first of all, a fan-shaped blank is punched out from a paper material laminated with the above-mentioned thermoplastic resin, is wrapped around a cylindrical die in a state in which its both edge parts are fused through a gas burner for example, and joined to each other, thereby forming the barrel part 1 (Step 61).

[0056] Moreover, circular bottom paper punched out from a similar paper material is choked and is joined to the inside of the bottom edge of the barrel part 1 while it is vacuum-adsorbed by the cylindrical die simultaneously with bonding of the edge parts of the barrel part 1. Then, the bottom edge of the barrel part 1 is folded and press-fitted to the side of the bottom part 2, thereby joining the bottom part 2 to the barrel part 1 (Step 62) .

[0057] Subsequently, in a curling process, the top edge of the barrel part 1 is rolled outward while being rotated through a tool, thereby forming a flange part having a circular cross-section in the radial direction (X direction) of the barrel part 1 (Step 63).

[0058] Subsequently, the outer peripheral edge of the flange part with the circular cross-section is pressed as shown in Fig. 2, thereby forming the step part 33 (Step 64). Accordingly, the paper cup 100 opened at an upper part thereof is manufactured.

[0059] Then, the paper cup 100 is filled with contents such as ice cubes and beverage and a lid material is joined to the aperture (sealing surface 31 of the flange part 3) by heat sealing, thereby hermetically sealing the paper cup 100 (Step 65) .

[0060] At this heat sealing time, the seal head first presses the sealing surface 31 and then presses the step part 33 with a delay. Therefore, the sealing strength in the sealing surface 31 is higher and the sealing strength in the step part 33 is lower by an amount corresponding to the time lag.[Conclusion]

[0061] As described above, in accordance with the present embodiment, providing the outer peripheral edge of the upper surface of the flange part 3 with the step part 33 enables suppression of the deformation of the flange part 3 at the time of sealing with a lid material and at the time of opening the lid material. Accordingly, without changing sealing conditions of the lid material, it is possible to prevent a change of the opening outer diameter dimensions of the flange part 3 at the time of sealing and prevent deterioration of the fitting property of the lid (over-cap) fitted to the flange part 3 and to stably open it at the time of opening.[Modified Examples]

[0062] The present technology is not limited to the above-mentioned embodiment and various modifications can be made without departing from the gist of the present technology.

[0063] The shapes of the flange part 3 and the step part 33 are not limited to those shown in the Fig. 2. For example, the step part 33 shown in Fig. 2 is constituted by the bottom surface substantially parallel to the sealing surface 31 and the oblique surface connecting the sealing surface 31 and the bottom surface. However, the oblique surface may be a surface closer to the perpendicular surface and the bottom surface may be formed to be wider.

[0064] In the above-mentioned embodiment, the paper cup 100 is manufactured by forming the barrel part 1 and the bottom part 2 as different parts and bonding the bottom part 2 to the barrel part 1. However, a container such as a paper cup may be manufactured by integrally forming a barrel part and a bottom part from a single paper material. Also in this case, the flange part can be molded in a similar way to that in the above-mentioned embodiment.

[0065] In the above-mentioned embodiment, the paper cup 100 is shown as the container. However, the application of the container is not limited to the cap, and for example, may be storage of food products such as confectionery products.

Claims

1. A container comprising: a cylindrical barrel part having a side seam part at a side surface thereof, the side seam part being formed by bonding a paper material coated with a thermoplastic resin; a flange part which is formed of the paper material rolled at one edge of the barrel part and to which a lid material is bonded by heat sealing; and a bottom part formed at another edge of the barrel part, wherein the flange part has a step part with a predetermined height and a predetermined width at an outer peripheral edge of an upper surface thereof.

2. The container according to claim 1, wherein the predetermined height is equal to or larger than a half of a thickness of the paper material.

3. The container according to claim 1, wherein assuming that a boundary between the barrel part and the flange part is a fulcrum point of force for opening the lid material and a starting point of the step part is a working point of the force, the predetermined width is set to be such a length that a moment of the force is smaller than 60 N*mm.

4. The container according to claim 1, wherein the flange part includes a double-layered part which is located in a lower portion of the step part, where two portions of the paper material overlap each other in a cross-sectional view in a radial direction of the barrel part, and a triple-layered part which is located on an inner peripheral side with respect to the double-layered part, where three portions of the paper material overlap one another in the cross-sectional view, the double-layered part has a single bonding part that bonds two pieces of paper, and the triple-layered part has two bonding parts that adhere three pieces of paper.

5. The container according to claim 4, wherein the flange part has a space between the bonding parts of the double-layered part and the bonding parts of the triple-layered part.

6. A container manufacturing method comprising: forming a cylindrical barrel part having a side seam part at a side surface by bonding a paper material coated with a thermoplastic resin; forming a bottom part at one edge of the barrel part; forming a curl-shaped flange part by rolling another edge of the barrel part; and forming a step part with a predetermined height and a predetermined width by stamping an outer peripheral edge of the flange part.

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