Container and container manufacturing method

Abstract

A container includes: a cylindrical body part that is formed from a body member; a flange part that is formed by rolling one end of the body member outward; a bottom part that is formed from another end of the body member and a bottom member; and a seal member that has a thermoplastic resin to be bonded to an upper surface of the flange part by heat sealing. The flange part includes a first curl portion located on an outermost circumference of the body part in a radial direction, and a second curl portion overlapping with the first curl portion on an inside of the first curl portion. The flange part also includes a bonding portion that bonds the first curl portion and the second curl portion to each other in at least one location in a cross-sectional view in the radial direction, and has a space inside the second curl portion, the space having a thickness equal to or larger than a thickness of the body member.

Description

Technical Field

[0001] The present invention relates to a container for food and beverages and to a method of manufacturing the container.Background Art

[0002] Conventionally, as containers (paper cups) for food and beverages, containers each including a body part including a side seam part (bonded part) and a bottom part attached to the inside of the body part, which are both made of a sheet-like material, and each having an open end that is sealed using a film-like seal member (top seal member), have been widely used.

[0003] The open end of the above-mentioned container is provided with a flange part facing outward from the container. After the container is filled with contents such as beverages, a seal member is bonded to the flange part by heat sealing, for example.

[0004] Patent Literature 1 mentioned below describes that the flange part (mouth roll) described above is formed such that its cross-section has a circular shape (curl shape).

[0005] Patent Literature 2 mentioned below describes that the flange part (cup rim part) described above is pressed in a vertical direction 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, if the flange part has the curl shape as described in Patent Literature 1 above, the flange part is deformed during sealing with a seal member, and the dimension of an outer diameter is changed, which may deteriorate fitting property of a lid (over cap) to be fitted to the flange part.

[0008] In addition, if the flange part has the curl shape as described in Patent Literature 1 above and if the flange part has the pressed flat shape as described in Patent Literature 2 above, the flange part is deformed when the seal member is opened, which makes it impossible to open the seal member stably, and as in the above case, the fitting property of the lid may be deteriorated.

[0009] Further, if a sealing machine is adjusted for sealing resin cups, and a load applied during sealing cannot be adjusted for paper cups, the sealing must be strong, resulting in poor openability.

[0010] In view of the circumstances as described above, it is an object of the present invention to provide a container and a method of manufacturing the container that are capable of suppressing deformation of a flange part (deformation of an outer diameter) during sealing and opening of a seal member, and easily opening the seal member even under strong sealing conditions.Solution to Problem

[0011] In order to achieve the above object, a container according to an embodiment of the present invention includes: a cylindrical body part that is formed from a body member; a flange part that is formed by rolling one end of the body member outward; a bottom part that is formed from another end of the body member and a bottom member; and a seal member that has a thermoplastic resin to be bonded to an upper surface of the flange part by heat sealing. The flange part includes a first curl portion located on an outermost circumference of the body part in a radial direction, and a second curl portion overlapping with the first curl portion on an inside of the first curl portion. The flange part also includes a bonding portion that bonds the first curl portion and the second curl portion to each other in at least one location in a cross-sectional view in the radial direction, and has a space inside the second curl portion, the space having a thickness equal to or larger than a thickness of the body member.

[0012] With this configuration, providing the bonding portion between the first curl portion and the second curl portion makes it possible to suppress the turning-up of the curl during opening. Further, if the space is provided inside the second curl portion, the space works as a cushion during the heat sealing of the seal member (springback effect), and a resin pool formed between the flange part and the seal member when the space is crushed once by a seal head is peeled when the space is restored, to thereby form a notch. The notch works as a point of action during opening, which makes it possible to easily open the seal member even under strong sealing conditions. Here, the thickness of the paper material is about 0.3 mm, for example, but it is not limited thereto.

[0013] The container may include a resin pool portion between the flange part and the seal member, the resin pool portion being formed of the thermoplastic resin melted during the heat sealing, and a notch that is formed between the resin pool portion and the flange part, the notch being formed by peeling of the resin pool portion from the flange part due to a springback effect of the space during the heat sealing.

[0014] The flange part may have a first length in a height direction and a second length larger than the first length in a width direction.

[0015] Thus, the flange part has a crushed shape more than a conventional round curl shape, which makes it possible to further suppress deformation of the flange part during sealing and opening of the seal member and stabilize the outer diameter.

[0016] The flange part may include a step portion having a predetermined height and a predetermined width at an outer circumferential end of the upper surface of the flange part.

[0017] This makes it possible to stabilize the outer diameter and also locate a point of action during opening on the further inner circumferential side in order not to heat-seal the step portion. In addition, a resin pool is more likely to be formed in the step portion during the heat sealing and thus a notch is more likely to be formed, which makes it possible to further improve the openability. Further, a space on the outer circumferential end side of the flange part becomes narrower than a space on the inner circumferential side of the flange part due to the step portion, which makes it possible to achieve both the springback effect and the stability of the outer diameter.

[0018] The bonding portion may be provided on a side closer to a boundary between the flange part and a side surface of the body part than an end portion of the body member, the end portion being rolled outward.

[0019] This makes it possible to further suppress the turning-up of the curl of the flange part during opening and to improve the openability.

[0020] A method of manufacturing a container according to another embodiment of the present invention includes: joining side surfaces of a body member to form a cylindrical body part; joining one end of the body member and a bottom member to form a bottom part; performing processing of rolling another end of the body member outward to form a curl-shaped flange part; bonding a first curl portion and a second curl portion of the flange part to each other, the first curl portion being located on an outermost circumference of the body part in a radial direction, the second curl portion overlapping with the first curl portion on an inside of the first curl portion, to form a space inside the second curl portion, the space having a thickness equal to or larger than a thickness of the body member; and bonding a seal member to an upper surface of the flange part by heat sealing.Advantageous Effects of Invention

[0021] As described above, according to the present invention, it is possible to suppress deformation of the flange part during sealing and opening of the seal member and to easily open the seal member even under strong sealing conditions. However, this effect does not limit the present invention.Brief Description of Drawings

[0022] [Fig. 1] Fig. 1 is a view showing a front outer appearance of a paper cup according to an embodiment of the present invention. [Fig. 2] Fig. 2 is an enlarged cross-sectional view of a flange part in Fig. 1. [Fig. 3] Fig. 3 is a diagram showing experimental results of openability of the flange part as compared to a comparative example. [Fig. 4] Fig. 4 is a diagram showing curves of a relationship between an elapsed time (opening position) during opening of the flange part and an opening strength as compared to the comparative example. [Fig. 5] Fig. 5 is a diagram showing a state of a resin pool at an outer circumference portion of the flange part as compared to the comparative example. [Fig. 6] Fig. 6 is a cross-sectional view showing a state change of the flange part during top sealing. [Fig. 7] Fig. 7 is a flowchart showing a manufacturing process of the paper cup. Mode(s) for Carrying Out the Invention

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.[Outer Appearance of Paper Cup]

[0024] Fig. 1 is a view showing a front outer appearance of a paper cup as a container according to an embodiment of the present invention. Fig. 1 is partially shown in cross-section.

[0025] As shown in the figure, a paper cup 100 according to this embodiment includes a body part 1 and a bottom part 2.

[0026] The body part 1 is made of a paper material (base paper) as a raw material, which is obtained by being coated (laminated) with a thermoplastic resin such as polyethylene, polypropylene, or polyester, punched out as a fan-shaped blank (body member), wrapped around a cylindrical mold to overlap side end portions thereof, and bonded together. By bonding of the side end portions together, a side seam part 4 is formed on the side surface of the body part 1 from the top to the bottom of the body part 1.

[0027] The bottom part 2 is a circular bottom paper (bottom member) that is punched out from the same paper material as the body part 1, subjected to drawing, and bonded to the inside of the bottom end of the body part 1 at the same time as the bonding of the body part 1 as described above.

[0028] At the bottom end of the body part 1 to which the bottom part 2 has been bonded, the paper material is folded inward and crimped. At the top end of the body part 1, a flange part 3 is formed with one end of the body member being rolled outward. The body part 1 is open at the flange part 3.

[0029] After the paper cup 100 is filled with contents such as beverages and ice, for example, a seal member such as a polyethylene film is bonded to the flange part 3 by heat sealing, so that the paper cup 100 is sealed.

[0030] The paper material as a raw material of the body part 1 and the bottom part 2 is formed of a plurality of layers, for example. In the paper material, a synthetic resin layer, a foam layer, a metal layer, an inorganic vapor-deposited film, and the like may be laminated other than the laminated layer made of a thermoplastic resin.

[0031] To make the paper cup 100 more difficult to tear when the contents are hard objects such as ice, the body part 1 and the bottom part 2 may be further laminated with a resin film made of polyethylene terephthalate or the like.[Shape of Flange Part]

[0032] Fig. 2 is an enlarged cross-sectional view of the flange part 3 (E part in Fig. 1).

[0033] As shown in the figure, the flange part 3 includes a seal surface 31 to which the seal member described above is to be bonded, a curl portion 32 in which the body part 1 is rolled, and a step portion 33.

[0034] A width (length in the X-direction) A of the flange part 3 is larger than a height (thickness: length in the Y-direction) B of the flange part 3. In other words, unlike a conventional round curl shape, the flange part 3 of this embodiment has a crushed shape in the height direction (Y-direction).

[0035] The width A of the flange part 3 is, for example, 2 to 5 mm, and the thickness B of the flange part 3 is about 1 to 1.5 mm, which is more than four times a thickness T of the paper material (e.g., 0.3 mm).

[0036] Further, the flange part 3 includes a first curl portion 34 located at the outermost circumference of the body part 1 in a radial direction (X-direction) and a second curl portion 35 that overlaps with the first curl portion 34 on the inside thereof. The flange part 3 includes a bonding portion 36 that bonds the first curl portion 34 and the second curl portion 35 at only one location in the cross-sectional view in the radial direction. In other words, the curl portion 32 of the flange part 3 is bonded only at the single bonding portion 36.

[0037] The bonding portion 36 prevents the curl of the flange part 3 from being turned up when the seal member is opened. The bonding portion 36 is favorably provided on the side closer to the boundary between the flange part 3 and the side surface of the body part 1 (left side in Fig. 2) than the rolled end portion of the paper material. This can further enhance the above-mentioned effect of preventing the turning-up.

[0038] A space S is formed inside the second curl portion 35 of the flange part 3. The space S is formed as a result of the bonding of the curl portion 32 only at the bonding portion 36 (not bonding of the second curl portion 35 and a layer located below). The space S is secured by the thickness T of the paper material in the Y-direction or larger (in the example of the figure, about twice the thickness T).

[0039] The step portion 33 is formed at an outer circumferential end of the upper surface of the flange part 3. As will be described later, the step portion 33 is formed by press-molding the outer circumferential end of the round-curled flange part.

[0040] If the step portion 33 is provided and when the seal member is sealed, a seal head does not come into contact with the step portion 33 but comes into contact with only the inner side of the flange part 3 (seal surface 31) (or even if seal head does, the contact is weak), which can prevent the flange part 3 from being deformed. Additionally, when the seal member is opened, since the point of action with respect to the fulcrum of the opening force (the boundary between the body part 1 and the flange part 3) is located inside (a starting point of the step portion 33) relative to the outer circumferential end of the flange part 3, the moment of the force is reduced, which is effective for easy openability (easy peeling). Further, when the step portion 33 is provided, the curl is subjected to pressing (crushed once before sealing), so that the deformation of the flange part 3 can be suppressed.

[0041] Here, a height D of the step portion 33 (a distance between the seal surface 31 and the bottom surface of the step portion 33) is about equal to the thickness T of the paper material, but it is not limited thereto and may be about half of the thickness T.

[0042] Additionally, a width C of the step portion 33 (a distance from the boundary between the seal surface 31 and the step portion 33 to the outer circumferential end of the flange part 3) is, for example, about one-fourth to one-third of the width A of the flange part 3. If the sealing conditions are appropriate (if strong sealing is not performed near the step portion 33), a larger width C reduces the moment required for opening, thus improving the easy openability.[Openability in Flange Part]

[0043] Fig. 3 is a diagram showing experimental results of the openability of the seal member in the flange part 3 described above as compared to a comparative example. In the comparative example, the layers of a flange part are bonded at multiple locations such that the space S described above is not formed.

[0044] Note that a seal member is sealed under the sealing conditions of: temperature of 165°C; load of 130 kg / cup; and two times of crimping. A sealing load for paper cups is generally about 60 kg / cup, and the above-mentioned load can be considered to be a strong sealing condition (this sealing load is equivalent to a sealing load for cups made of resin (PET)).

[0045] As shown in the figure, in a total of five opening experiments, the flange part in the comparative example could not be opened even once, whereas the flange part 3 in this embodiment was successfully opened all five times with a stable opening strength with a maximum value of 26 N, a minimum value of 22 N, and an average value of 24 N.

[0046] Thus, the flange part 3 according to this embodiment makes it possible to stably open the seal member even under strong sealing conditions.

[0047] Fig. 4 is a diagram showing curves of the relationship between an elapsed time (opening position) during opening of the flange part 3 and an opening strength as compared to the above comparative example. Note that, in the flange part according to the comparative example, the seal member cannot be opened under the strong sealing conditions as shown in Fig. 3 above and the opening strength cannot be measured, and thus in the experiment shown in Fig. 4, the seal member was sealed under proper sealing conditions instead of the strong sealing conditions.

[0048] As shown in the diagram, the flange part according to the comparative example has a peak of 14 N at the boundary between the body part and the flange part, which is the fulcrum of the force to open the seal member, and also has a strong peak of 16 N at the outer circumferential end of the flange part, which is the point of action of the opening force. The fact that the opening strength is high at the outer circumferential end, which is the point of action of the opening force, is thought to cause an opening failure as described above under the strong sealing conditions.

[0049] In contrast, in the flange part 3 according to this embodiment, although a slightly strong peak of 13 N occurs at the boundary between the body part 1 and the flange part 3, which is the fulcrum, the opening strength at the point of action (step portion 33) on the outer circumferential side is 10 N, indicating that no strong peak that may lead to an opening failure occurs on the outer circumferential side.

[0050] Here, the reason why the flange part 3 of this embodiment has high openability (especially, the opening strength does not increase on the outer circumferential side) even under the strong sealing conditions as described above will be discussed.

[0051] Fig. 5 is a diagram showing a state of a resin pool at an outer circumference portion of the flange part 3 as compared to the comparative example.

[0052] As shown in the figure, in the flange part according to the comparative example, it is found that the resin pool that has been formed during heat sealing adheres to the boundary with the seal member.

[0053] Meanwhile, in the flange part 3 according to this embodiment, it is found that the resin pool at the boundary with the seal member is peeled off and a notch is formed between the seal member (resin pool) and the flange part 3.

[0054] Fig. 6 is a cross-sectional view showing a state change of the flange part 3 during top sealing. (A) of the figure shows an unsealed state, followed by (B) through (D), and then (E) shows a top-sealing completed state. The lower part of the same figure shows enlarged views of (D) and (E).

[0055] With the paper cup 100 being filled with contents, the flange part 3 is set in a seal bucket S1 as shown in (B) of the figure from the unsealed state shown in (A) of the figure, and a seal member 40 is then set on the seal surface 31 of the flange part 3.

[0056] Subsequently, as shown in (C) of the figure, a seal head S2 abuts on the seal member 40 from above to press the seal member 40 while heating it as shown in (D) of the figure. When the seal head S2 is raised as shown in (E) of the figure, the seal member 40 is fused onto the flange part 3, and the heat sealing is completed.

[0057] At that time, in the state where the flange part 3 is compressed as shown in (D) of the figure, the space S is crushed as indicated by the arrows in the same figure, and the resin melted from the surfaces of the seal member 40 and the flange part 3 flows to both ends of the flange part 3 in the X-direction, thus forming a resin pool portion P.

[0058] When the seal head S2 is raised as shown in (E) of the figure, the height of the flange part 3 returns to its original state due to a cushioning effect (springback effect) of the space S as indicated by the arrows in the same figure, and thus the resin pool portion P described above is peeled off from the flange part 3, and a notch (cutout) N is formed.

[0059] In other words, the paper cup 100 sealed with the seal member 40 in this embodiment includes the resin pool portion P, which is formed of a thermoplastic resin melted during heat sealing, between the flange part and the seal member 40, and the notch N formed between the resin pool portion P and the flange part 3 by the peeling of the resin pool portion P from the flange part 3 due to the springback effect of the space S during heat sealing.

[0060] The notch N formed in such a manner becomes the point of action of the opening force when the seal member 40 is opened, which makes it possible to easily open the seal member 40 even under the strong sealing conditions.[Method of Manufacturing Paper Cup]

[0061] Next, the method of manufacturing the paper cup 100 will be described. Fig. 7 is a flowchart showing a flow of a manufacturing process of the paper cup 100.

[0062] As shown in the figure, first, a fan-shaped blank is punched out from the above-mentioned paper material laminated with a thermoplastic resin, wrapped around a cylindrical mold with the two end portions of the blank being melted by a gas burner or the like, and then bonded together to form the body part 1 (Step 61).

[0063] In addition, a circular bottom paper punched out from the same paper material described above is subjected to drawing and, while being vacuum-suctioned by the cylindrical mold described above, bonded to the inside of the bottom end of the body part 1 at the same time as the bonding of the end portions of the body part 1. The bottom end of the body part 1 is then folded toward the bottom part 2 side and crimped, thereby joining the bottom part 2 to the body part 1 (Step 62).

[0064] Subsequently, in the curling processing, the top end of the body part 1 is rolled outward while being rotated with a tool, thereby forming a flange part (round curl) with a circular cross-section in the radial direction (X-direction) of the body part 1 (Step 63) .

[0065] At that time, before the body part 1 is rolled, the portion around the top end is rolled over the circumferential direction while being melted using hot air (heated air), a gas burner, ultrasonic waves, or the like, so that the first curl portion 34 and the second curl portion 35 are bonded to each other to form the bonding portion 36. As described above, the turning-up of the curl of the flange part 3 during opening can be further suppressed on the side closer to the boundary between the flange part 3 and the side surface of the body part 1. Additionally, the bonding portion 36 is formed between the first curl portion 34 and the second curl portion 35, so that the space S is also formed inside the second curl portion 35.

[0066] Subsequently, the flange part with the circular cross-section is then pressed by a mold with a convex portion on its outer circumferential end side to form a step portion 33 and also form a flange part 3 having a crushed shape in the height direction (horizontally long cross-section) (Step 64). An open-top paper cup 100 is thus manufactured. The flange part 3 is formed in a horizontally long cross-sectional shape, which makes it possible to prevent a change in the outer diameter of the flange part 3 during sealing and opening, and to both stabilize the outer diameter and improve the openability by forming the step portion 33 in the flange part 3.

[0067] The paper cup 100 is then filled with contents such as ice and beverages, and the seal member 40 is bonded to the opening (the seal surface 31 of the flange part 3) by heat sealing as shown in Fig. 6, so that the paper cup 100 is sealed (Step 65).

[0068] During the heat sealing, a notch N is formed from the resin pool P of the step portion 33 due to the cushioning effect (springback effect) of the space S in the flange part 3. This can improve the openability.[Conclusion]

[0069] As described above, according to this embodiment, bonding the flange part 3 at only one location makes it possible to suppress deformation of the flange part 3 during sealing and opening of the seal member 40. Further, bonding at only one location generates the space S inside the second curl portion 35, which makes it possible to form a notch N by the resin pool P between the flange part 3 and the seal member 40 when the seal member 40 is heat-sealed and, when the notch N works as the point of action during opening of the seal member 40, to easily open the seal member 40 even under the strong sealing conditions (when there is no choice but to take such conditions).

[0070] Further, since the step portion 33 is not heat-sealed, the point of action at the time of opening can be located on the further inner circumferential side. Additionally, since the resin flows to the step portion 33 during heat sealing and a resin pool P is easily formed, the notch N can be easily formed, thus further improving the openability.[Modified Examples]

[0071] The present technology is not limited to the embodiment described above, but may be variously modified within the scope that does not depart from the gist of the present technology.

[0072] In the embodiment described above, the bonding portion 36 of the flange part 3 is provided at only one location between the first curl portion 34 and the second curl portion 35 in the radial direction (X-direction) of the body part 1. However, the bonding portion 36 may be provided at multiple locations between the first curl portion 34 and the second curl portion 35. Note that if many bonding portions 36 are provided and the curl portion 32 is firmly fixed, the springback effect due to the space S cannot be obtained. Thus, from this viewpoint, it is favorable to provide the bonding portion 36 at only one location.

[0073] In the embodiment described above, the bonding portion 36 of the flange part 3 is formed when a round curl is formed by rolling, but after the round curl is formed by rolling, the bonding portion 36 may be formed by being pressed by an ultrasonic horn or the like during pressing to form the step portion 33.

[0074] The shapes of the flange part 3 and the step portion 33 are not limited to those shown in Fig. 2. For example, the step portion 33 shown in Fig. 2 is formed by a bottom surface nearly parallel to the seal surface 31 and a slope connecting the seal surface 31 and the bottom surface. However, the slope may be made more nearly perpendicular and the bottom surface may be formed wider.

[0075] In the embodiment described above, the paper cup 100 is manufactured by manufacturing the body part 1 and the bottom part 2 as different parts and bonding the bottom part 2 to the body part 1. However, a container such as a paper cup may be manufactured by integrally forming a body part and a bottom part from a single sheet of paper material. In this case as well, the flange part may be formed in the same manner as in the above embodiment.

[0076] Additionally, in the embodiment described above, the paper cup 100 is formed by forming the body part 1 with the side seam part 4 and the bottom part 2 from a paper material previously coated with a thermoplastic resin and connecting both of them. However, the paper cup 100 may also be formed as a composite paper container in which a body part and a bottom part are formed from a paper material not coated with a thermoplastic resin, the body part (side seam part thereof) and the bottom part are bonded to each other with a resin (adhesive) to form a paper container, and a resin film is attached to the inner surface of the paper container by vacuum- and / or pressure-forming.

[0077] In the embodiment described above, the paper cup 100 is shown as a container, but the use application of the container is not limited to cups, and the container may be used to contain food such as confectionery, for example.Reference Signs List

[0078] 1body part 2bottom part 3flange part 4side seam part 31seal surface 32curl portion 33step portion 34first curl portion 35second curl portion 36bonding portion 40seal member 100paper cup Sspace S1seal bucket S2seal head Presin pool Nnotch

Claims

1. A container, comprising: a cylindrical body part that is formed from a body member; a flange part that is formed by rolling one end of the body member outward; a bottom part that is formed from another end of the body member and a bottom member; and a seal member that has a thermoplastic resin to be bonded to an upper surface of the flange part by heat sealing, wherein the flange part includes a first curl portion located on an outermost circumference of the body part in a radial direction, and a second curl portion overlapping with the first curl portion on an inside of the first curl portion, includes a bonding portion that bonds the first curl portion and the second curl portion to each other in at least one location in a cross-sectional view in the radial direction, and has a space inside the second curl portion, the space having a thickness equal to or larger than a thickness of the body member.

2. The container according to claim 1, wherein the container includes a resin pool portion between the flange part and the seal member, the resin pool portion being formed of the thermoplastic resin melted during the heat sealing, and a notch that is formed between the resin pool portion and the flange part, the notch being formed by peeling of the resin pool portion from the flange part due to a springback effect of the space during the heat sealing.

3. The container according to claim 1 or 2, wherein the flange part has a first length in a height direction and a second length larger than the first length in a width direction.

4. The container according to claim 3, wherein the flange part includes a step portion having a predetermined height and a predetermined width at an outer circumferential end of the upper surface of the flange part.

5. The container according to claim 1 or 2, wherein the bonding portion is provided on a side closer to a boundary between the flange part and a side surface of the body part than an end portion of the body member, the end portion being rolled outward.

6. A method of manufacturing a container, comprising: joining side surfaces of a body member to form a cylindrical body part; joining one end of the body member and a bottom member to form a bottom part; performing processing of rolling another end of the body member outward to form a curl-shaped flange part; bonding a first curl portion and a second curl portion of the flange part to each other, the first curl portion being located on an outermost circumference of the body part in a radial direction, the second curl portion overlapping with the first curl portion on an inside of the first curl portion, to form a space inside the second curl portion, the space having a thickness equal to or larger than a thickness of the body member; and bonding a seal member to an upper surface of the flange part by heat sealing.

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