Method for sealing tube containers

Abstract

To provide a method of sealing a tube container capable of increasing seal strength while suppressing thermal deformation and air bubble occurrence at one end of a trunk of the tube container.SOLUTION: Provided is a method of sealing a tube container, the tube container comprising: a spout that has a spout cylinder portion and a flange portion connected to one end of the spout cylinder portion and extending outward of the spout cylinder portion; and a tubular trunk that consists of a sheet, has a back-lined seal portion extending from one end over to the other end formed therein, is closed at the one end, and is attached with the spout at the other end, wherein a content is stored. The method of sealing the tube container includes: a first heating step of heating an inner face at one end of the back-lined seal portion of the trunk formed with the back-lined seal portion, attached with the spout at the other end and filled with the content and an inner face of an opposed portion facing the one end of the back-lined seal portion; and a second heating step of closing the one end of the back-lined seal portion and the one end of the trunk including the opposed portion together by heat seal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sealing method for tube containers. [Background Art]

[0002] Tube containers are widely used as packaging materials for pharmaceuticals, cosmetics, foods and the like. For example, Patent Document 1 describes a tube container configured including a pouring unit that pours out contents, and a body portion welded to the pouring unit and accommodating the contents. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2016-199280 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The body portion of the above-mentioned tube container is formed by forming a sheet into a cylindrical shape, partially overlapping the sheets to perform back-sealing, and then sealing one end of the body portion. Among the sealed one end of the body portion, three or more sheets overlap in a portion including the back-sealed portion, and two sheets overlap in a portion not including the back-sealed portion. Therefore, at one end of the body portion, the heat capacity of the portion including the back-sealed portion is larger than the heat capacity of the portion not including the back-sealed portion. Accordingly, when sealing one end of the body portion by heat sealing, if one end of the body portion is heated until the sealing strength of the portion including the back-sealed portion reaches a desired sealing strength, the temperature of the portion not including the back-sealed portion becomes excessively high, which may cause thermal deformation and air bubble entrapment. Further, when one end of the body portion is heated so as not to cause thermal deformation and air bubble entrapment in the portion not including the back-sealed portion, there is a risk that the sealing strength of the portion including the back-sealed portion becomes insufficient.

[0005] Based on the above circumstances, the present invention aims to provide a method for sealing a tube container that can increase the seal strength while suppressing thermal deformation and the occurrence of air bubbles at one end of the body of the tube container. [Means for solving the problem]

[0006] The present invention relates to a method for sealing a tube container, comprising: a cylindrical dispensing cylinder portion; a spout portion having a flange portion connected to one end of the dispensing cylinder portion and extending outward from the dispensing cylinder portion; and a tubular body portion made of a sheet, having a back-sealed portion extending from one end to the other end, with one end closed and the spout portion attached to the other end, the method for sealing a tube container that contains contents, wherein the inner surface of one end of the back-sealed portion of the body portion, which has the back-sealed portion formed and the spout portion attached to the other end and is filled with contents, and the inner surface of the opposing portion facing the one end of the back-sealed portion When they are separated from each other, the inner surface of one end of the back-sealed portion and the inner surface of the opposing portion The process includes a first heating step of heating the material, and a second heating step of closing one end of the body portion, including the back-sealed portion and the opposing portion, by heat sealing. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a method for sealing a tube container that can increase the seal strength while suppressing thermal deformation and the occurrence of air bubbles at one end of the body of the tube container. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing the schematic configuration of a tube container according to the embodiment. [Figure 2] This is a cross-sectional view along the line II-II shown in Figure 1. [Figure 3] This is an end view along the line III-III shown in Figure 1. [Figure 4] This is an end view along the IV-IV line shown in Figure 1. [Figure 5] This is a cross-sectional view showing an example of the layered structure of the sheets that make up the body of a tube container. [Figure 6] This is a flowchart showing the method for manufacturing a tube container according to the embodiment. [Figure 7] This is a bottom view showing the first heating step according to the embodiment. [Figure 8] This is a bottom view showing the second heating step according to the embodiment. [Modes for carrying out the invention]

[0009] Figure 1 is a perspective view showing the schematic configuration of a tube container according to an embodiment, Figure 2 is a cross-sectional view along the line II-II shown in Figure 1, Figure 3 is an end view along the line III-III shown in Figure 1, and Figure 4 is an end view along the line IV-IV shown in Figure 1. In the following explanation, "one end of the torso" refers to the lower end of the torso as shown in Figure 2. Furthermore, "one end of the torso" is a concept that includes both the end of the torso and a predetermined range extending from that end. "One end of the back-sealed portion" refers to the lower end of the back-sealed portion shown in Figure 2. Furthermore, "one end of the back-sealed portion" is a concept encompassing both one end of the back-sealed portion and a predetermined range extending from that end.

[0010] As shown in Figure 1, the tube container 100 comprises a tubular body 1 and a spout 2 attached to the body 1.

[0011] The body portion 1 is a component for containing the contents and is formed from a sheet 41 as shown in Figure 5. The body portion 1 is formed by rolling up a roughly rectangular sheet 41 having a pair of roughly parallel edges, overlapping and welding the portions of the sheet 41 that include each of the pair of edges, and then overlapping and welding the inner surfaces of one end of the sheet 41 together. The body portion 1 can be manufactured using a bag-making machine or a pillow / stick packaging machine, etc.

[0012] As shown in Figure 1, the spout portion 2 is a spout for dispensing the contents contained in the body portion 1 to the outside, and is molded from a material containing thermoplastic resin. The spout portion 2 has a dispensing cylinder portion 3 and a flange portion 4. The dispensing cylinder portion 3 is cylindrical. In this embodiment, the dispensing cylinder portion 3 is cylindrical. The shape of the dispensing cylinder portion 3 is not limited to cylindrical, and may be a square cylinder, hexagonal cylinder, or other rectangular cylinder shape.

[0013] As shown in Figure 2, the flange portion 4 is a flat plate that is connected to one end 6a of the dispensing cylinder portion 3 and extends outward from the dispensing cylinder portion 3. In this embodiment, the flange portion 4 extends in a direction perpendicular to the axial direction of the dispensing cylinder portion 3. In this embodiment, the flange portion 4 is formed in an annular shape, but the shape of the flange portion 4 is not limited as long as it can be joined to the body portion 1, and may be elliptical, oblong, track-shaped, polygonal, etc.

[0014] The thermoplastic resin used for the spout section 2 can be, for example, one of polyethylene, polypropylene, polyester, polyamide, and cyclopolyolefin, or a combination of two or more of these. The spout section 2 may also be molded from a material containing a thermoplastic resin and a filler other than resin. The filler can be one of talc, kaolin, paper powder, and cellulose fiber, or a combination of two or more of these. By using a mixture of thermoplastic resin and a filler other than resin as the material for the spout section 2, the amount of resin used can be reduced while maintaining moldability and heat-welding properties with the body section 1. The molding method for the spout section 2 is not particularly limited, but existing molding methods such as injection molding, thermoforming such as vacuum forming and hot plate pressure forming, and compression molding can be used.

[0015] A back-sealed seal portion 7 where sheets 41 are sealed to each other is formed on the body portion 1. As shown in FIG. 1, the back-sealed seal portion 7 extends from one end 5a to the other end 5b of the body portion 1. As shown in FIG. 3, in the present embodiment, the back-sealed seal portion 7 is formed by abutting the inner surfaces of the sheets 41 against each other in a palm-to-palm configuration and welding them. The back-sealed seal portion 7 is folded along the body portion 1. In the present embodiment, the back-sealed seal portion 7 is formed by overlapping three sheets 41. The configuration of the back-sealed seal portion 7 and the forming step for forming the back-sealed seal portion 7 will be described in detail later.

[0016] As shown in FIG. 1 and FIG. 2, a closed portion 10 sealed by welding the sheets 41 to each other is formed at one end 5a of the body portion 1. One end 5a of the body portion 1 is closed by the closed portion 10. As shown in FIG. 4, the closed portion 10 is formed by welding the inner surfaces 1a of the body portion 1 to each other. In the present embodiment, the closed portion 10 is formed by heat sealing. As shown in FIG. 1, the closed portion 10 includes a first closed portion 10a and a second closed portion 10b.

[0017] As shown in FIG. 4, the first closed portion 10a is a portion of the closed portion 10 that includes one end 7a of the back-sealed seal portion 7 and an opposing portion 9. The opposing portion 9 is a portion of the one end 5a of the body portion 1 that is welded to the one end 7a of the back-sealed seal portion 7. The opposing portion 9 is a portion of the one end 5a of the body portion 1 that opposes the one end 7a of the back-sealed seal portion 7. The first closed portion 10a is formed by welding the inner surface 7b of the one end 7a of the back-sealed seal portion 7 and the inner surface 9a of the opposing portion 9 by heat sealing. The inner surface 7b of the one end 7a of the back-sealed seal portion 7 and the inner surface 9a of the opposing portion 9 are each part of the inner surface 1a of the body portion 1. In the present embodiment, the first closed portion 10a is formed by overlapping the three sheets of the back-sealed seal portion 7 and the one sheet of the opposing portion 9. That is, the first closed portion 10a is formed by overlapping four sheets.

[0018] As shown in Fig. 1 and Fig. 4, the second blocking portion 10b is a portion of the blocking portion 10 that does not include the back seal portion 7 and the opposing portion 9. The second blocking portion 10b is formed by heat-sealing a pair of opposing inner surfaces 1a of the sheet 41 to each other. As shown in Fig. 4, in the present embodiment, the second blocking portion 10b is formed by overlapping two sheets.

[0019] As shown in Fig. 2, a portion within a predetermined range from the other end 5b of the body portion 1 is folded and sealed to the outer surface 8 of the flange portion 4 of the spout portion 2.

[0020] Fig. 5 is a cross-sectional view showing an example of the layer configuration of the sheet 41 constituting the body portion 1 of the tube container 100.

[0021] The body portion 1 of the tube container 100 is constituted by a sheet 41 mainly made of paper. The sheet 41 is a multilayer sheet obtained by laminating a base film layer 33, a barrier layer 34 and a sealant layer 35 in this order on one surface of a paper layer 32, laminating a paper protective layer 37 on the other surface of the paper layer 32, laminating an ink layer 38 and an overcoat varnish layer 39 on the paper protective layer 37, and pattern-coating a heat-weldable coating layer 40. Details of each layer will be described below. In the present embodiment, one surface side of the paper layer 32 is the inner surface side of the body portion 1, and the other surface side of the paper layer 32 is the outer surface side of the body portion 1.

[0022] The paper layer 32 is a structural layer that imparts strength and stiffness to the tube container 100. The type of paper constituting the paper layer 32 is not particularly limited, but single-gloss kraft paper or double-gloss kraft paper is preferably used in terms of having strength, bending resistance, and printability. Further, as the paper constituting the paper layer 32, water-resistant paper or oil-resistant paper may be used as necessary. Further, the paper layer 32 only needs to be paper containing 50% or more of pulp fibers, and may be a mixed paper containing resin fibers in addition to pulp fibers. The basis weight of the paper used for the paper layer 32 is 30 to 200 g / m 2 , and is preferably 50 to 120 g / m 2 in this embodiment.

[0023] The base film layer 33 is a layer that imparts heat resistance and physical strength to the sheet 41. The base film layer 33 also serves as the base layer for the barrier layer 34. The material of the base film layer 33 is not particularly limited, but from the viewpoint of heat resistance and physical strength, it is preferable to use a stretched film such as polypropylene, polyester, or polyamide.

[0024] The barrier layer 34 is a functional layer that blocks oxygen, water vapor, etc., to improve the preservation of the contents. The barrier layer 34 can be composed of one or more of the following: a vapor-deposited film of an inorganic compound such as silica or alumina, a vapor-deposited film of a metal such as aluminum, a metal foil such as aluminum, a plate-like mineral, and / or a coating film of a barrier coating agent containing a barrier resin. As the barrier resin used in the barrier coating agent, ethylene-vinyl alcohol copolymer (EVOH) or polyvinylidene chloride (PVDC) can be used, and a binder resin other than the barrier resin may be appropriately blended into the barrier coating agent.

[0025] The sealant layer 35 is a layer that provides heat-sealability to the inner surface of the sheet 41, i.e., the inner surface of the body portion 1. The material of the sealant layer 35 is not particularly limited, but it is preferably a thermoplastic resin such as polypropylene, polyethylene, cyclic polyolefin, or polyester. The sealant layer 35 uses a resin whose softening temperature is 20°C or more lower than the softening temperature of the base film layer 33. Preferably, the softening temperature of the sealant layer 35 is 40°C or more lower than the softening temperature of the base film layer 33. If the softening temperature of the sealant layer 35 is not 20°C or more lower than the softening temperature of the base film layer 33, it is undesirable because the base film layer 33 will soften when the closure portion 10 is sealed by heat sealing, which increases the likelihood of pinholes occurring. In this embodiment, the inner surfaces of one end 5a of the body portion 1 are heat-sealed together by the sealant layer 35.

[0026] The paper protective layer 37 is a layer that protects the paper layer 32 from the adhesion of contents and dirt. The material and formation method of the paper protective layer 37 are not particularly limited, but the paper protective layer 37 can be laminated by extrusion coating of a thermoplastic resin or by coating with a coating agent such as a water-resistant agent or an oil-resistant agent. The thickness of the paper protective layer 37 is preferably 0.2 to 50 μm, and more preferably 1 to 20 μm.

[0027] The ink layer 38 is a layer applied by printing for the purpose of displaying various information. The overcoat varnish layer 39 is a layer that provides abrasion resistance and other properties. The layering order of the ink layer 38 and the overcoat varnish layer may be reversed from that shown in Figure 5. Also, the overcoat varnish layer 39 may also serve as the paper protection layer 37.

[0028] The heat-weldable coating layer 40 is a layer that provides heat-weldability to the outer surface of the body 1. The heat-weldable coating layer 40 can be formed by applying a coating agent containing a thermoplastic resin with a melting point of 200°C or less, such as an acrylic polymer, polyolefin, polyvinyl acetate, or polyester, and drying it. In addition to the thermoplastic resin, the coating agent may also contain inorganic substances to prevent blocking.

[0029] The heat-weldable coating layer 40 may be applied to the entire outer surface of the sheet 41, but in this case, the coefficient of friction of the surface of the sheet 41 will increase, which may reduce the machinability in the process of processing the body portion 1 and subsequent processes. Therefore, it is more preferable in terms of machinability to apply the heat-weldable coating layer 40 to a part of the outer surface of the sheet 41 by pattern coating the coating agent. In this embodiment, the heat-weldable coating layer 40 is applied to at least the outer surface 23b of one edge portion 23 of the sheet 41 (described later) and the outer surface 25b of the first portion 25 (described later), as shown in Figure 3. The heat-weldable coating layer 40 may be applied to only one of either the outer surface 23b of one edge portion 23 of the sheet 41 or the outer surface 25b of the first portion 25 of the sheet 41.

[0030] The thickness of the sheet 41 constituting the body portion 1 is not particularly limited, but is preferably 100 to 300 μm. If the thickness of the sheet 41 constituting the body portion 1 is within this range, the body portion 1 can be easily processed into a cylindrical shape using a bag-making machine or a pillow / stick packaging machine. In addition, since the paper layer 32 provides strength and rigidity, it can be made thinner than a typical laminate tube (thickness 300 to 500 μm), and the amount of resin used can also be reduced. In this embodiment, the thickness of the sheet 41 is 250 μm. That is, the thickness of the sheet 41 is 100 μm or more. In this embodiment, as shown in Figure 4, the thickness of the first closure portion 10a is 1000 μm, and the thickness of the second closure portion 10b is 500 μm.

[0031] In addition, in the layer configuration of sheet 41 shown in Figure 5, one or more layers of the base film layer 33, barrier layer 34, paper protection layer 37, ink layer 38, and overcoat varnish layer 39 may be omitted.

[0032] As shown in Figure 1, the tube container 100 may further be equipped with a screw cap 11 that can be attached and detached by screwing it onto the dispensing cylinder portion 3 of the outlet portion 2. When the tube container 100 is equipped with a screw cap 11, it becomes easier to reseal the tube container 100 after it has been opened.

[0033] Furthermore, the tube container 100 may be equipped with a hinged cap instead of a screw cap 11. If a hinged cap is provided, the hinged cap may be attached to the spout portion 2 by screwing it onto the dispensing cylinder portion 3 shown in Figure 1. Alternatively, ribs may be provided on the outer surface of the dispensing cylinder portion 3 instead of screw threads, and the hinged cap may be attached to the spout portion 2 by fitting through the ribs.

[0034] Furthermore, a film that closes the dispensing cylinder 3 when the tube container 100 is unopened may be sealed to the other end 6b of the dispensing cylinder 3.

[0035] Furthermore, the tube container 100 may be designed so that the dispensing cylinder portion 3 can be opened with a pull tab. In this case, the dispensing cylinder portion 3 may also be further equipped with a screw cap that can be attached and detached by screwing.

[0036] The sealing method Ms for the tube container 100 according to this embodiment will be described below.

[0037] Figure 6 is a flowchart showing the manufacturing method of the tube container 100. The manufacturing method of the tube container 100 in this embodiment includes a back-sealing portion forming step S1, a spout attachment step S2, a filling step S3, a first heating step S4, and a second heating step S5. The sealing method Ms for the tube container 100 in this embodiment includes a first heating step S4 and a second heating step S5. In this specification, "workers, etc." includes workers and assembly equipment, etc., who perform each task. Each task may be performed by workers alone, by assembly equipment alone, or by workers and assembly equipment together.

[0038] The back-sealing portion formation step S1 is a step in which the back-sealing portion 7 is formed. In the back-sealing portion forming process S1, first, the worker wraps a roughly rectangular sheet 41 around a cylindrical jig (not shown) to roll it into a tube, and as shown in Figure 3, the inner surface 23a of one end edge 23 of the sheet 41 and the inner surface 24a of the other end edge 24 of the sheet 41 are overlapped in a gable shape. In other words, parts of the rolled-up tube of the sheet 41 are overlapped. Next, the worker folds the joined portions of the sheet 41 at approximately 90 degrees to create a stack of three sheets. At this time, the outer surface 23b of one edge portion 23 and the outer surface 25b of the first portion 25 adjacent to the one edge portion 23 come into contact. As described above, the outer surface 23b of one edge portion 23 and the outer surface 25b of the first portion 25 are provided with a heat-weldable coating layer 40 (not shown).

[0039] Next, the worker seals the overlapping portion of the three sheets using a sealing bar (not shown). At this time, the inner surface 23a of one edge 23 and the inner surface 24a of the other edge 24 are heat-sealed, and at the same time, the outer surface 23b of one edge 23 and the outer surface 25b of the first portion 25 are heat-sealed via a heat-sealable coating layer 40 (not shown). This forms a back-sealed portion 7 where the three sheets 41 overlap, and a substantially cylindrical body portion 1 with one end 5a and the other end 5b open. As shown in Figure 1, the back-sealed portion 7 is formed from one end 5a to the other end 5b of the body portion 1. Once the back-sealed portion 7 is formed, the back-sealed portion formation process S1 is completed.

[0040] The spout attachment step S2 is the step of attaching the spout 2 to the other end of the body 1. In the spout attachment process S2, as shown in Figure 2, the worker inserts the flange portion 4 of the spout portion 2 into the body portion 1 through the opening at the other end 5b of the body portion 1, folds a predetermined portion from the other end 5b of the body portion 1, and welds the predetermined portion from the other end 5b of the body portion 1 to the flange portion 4. As a method for welding the body portion 1 and the spout portion 2, ultrasonic welding, high-frequency welding, heat seal welding, hot air welding, compression molding of the body insert, etc. can be used, but ultrasonic welding is preferred because it is less affected by the heat insulation properties of the paper. When the body portion 1 is sealed to the spout portion 2 and the spout portion 2 is attached to the other end of the body portion 1, the spout attachment process S2 is completed.

[0041] The filling process S3 is the process of filling the inside of the body 1 with contents (not shown). The contents are filled into the inside of the body 1 through the opening at one end 5a of the body 1. The filling process S3 is completed when the inside of the body 1 is filled with contents.

[0042] The first heating step S4 is a step of heating the inner surface 7b of one end 7a of the back-sealed portion 7 of the body portion 1, which has a back-sealed portion 7 formed thereon, a spout portion 2 attached to the other end 5b, and is filled with contents, and the inner surface 9a of the opposing portion 9. In the first heating step S4, as shown in Figure 7, the worker first inserts the air blower nozzle 20 into the body 1 through the opening 5a at one end of the body 1. The air blower nozzle 20 is connected to a compressor (not shown). The air blower nozzle 20 has a first air blower hole 20a and a second air blower hole 20b. The worker holds the air blower nozzle 20 with the first air blower hole 20a facing the inner surface 7b of one end 7a of the back sealing portion 7 and the second air blower hole 20b facing the inner surface 9a of the opposing portion 9. At this time, it is preferable for the worker to hold the body 1 in a substantially elliptical shape so that the distance between one end 7a of the back sealing portion 7 and the opposing portion 9 is shortened. This allows the distance between one end 7a and the opposing end 9 of the back sealing portion 7 and the air blower nozzle 20 to be shortened, so that warm air HA can be blown accurately to the inner surface 7b of one end 7a and the inner surface 9a of the opposing end 9.

[0043] Next, the worker blows hot air HA from a compressor (not shown) into the blower nozzle 20. As a result, the hot air HA is blown to the inner surface 7b of one end 7a of the back-sealed portion 7 via the first blower hole 20a, and to the inner surface 9a of the opposing portion 9 via the second blower hole 20b. Therefore, the inner surface 7b of one end 7a of the back-sealed portion 7 and the inner surface 9a of the opposing portion 9 are heated and softened. The target temperature of the inner surface 7b of one end 7a of the back-sealed portion 7 and the target temperature of the inner surface 9a of the opposing portion 9 in the first heating step S4 can be appropriately set based on the softening temperature of the sealant layer 35, the heat capacity of the back-sealed portion 7 and the heat capacity of the opposing portion 9, and the thermal conductivity of the sheet 41. In the first heating step S4, the target temperature of the inner surface 7b of one end 7a of the back-sealed portion 7 and the target temperature of the inner surface 9a of the opposing portion 9 may be the same or different. When the temperature of the inner surface 7b of one end 7a of the back-sealed portion 7 and the temperature of the inner surface 9a of the opposing portion 9 reach their respective target temperatures, the first heating step S4 is terminated. In this embodiment, the temperature of the hot air HA was set to 220-270°C.

[0044] The second heating step S5 is a step in which one end 5a of the body portion 1 is sealed by heat sealing. In the second heating step S5, as shown in Figure 8, the worker inserts one end 5a of the body portion 1 between a pair of seal bars 21, bringing the inner surfaces 1a of one end 5a of the body portion 1 into contact with each other, while heating the entire outer surface 1b of one end 5a of the body portion 1. As a result, the inner surfaces 1a of one end 5a of the body portion 1 are heat-welded together, forming the closed portion 10 shown in Figure 1. More specifically, as shown in Figure 4, in the first closed portion 10a, the inner surface 7b of one end 7a of the back-sealed portion 7 and the inner surface 9a of the opposing portion 9 are heat-welded together to form a seal. In the second closed portion 10b, the inner surfaces 1a of the sheet 41 are heat-welded together to form a seal. At this time, the seal strength of the first closed portion 10a and the seal strength of the second closed portion 10b are approximately the same, and the entire closed portion 10 is sealed with an appropriate seal strength. Furthermore, no thermal deformation or air bubble inclusion occurred in the second closed portion 10b. In this embodiment, the temperature of the pair of sealing bars 21 was set to 250-300°C.

[0045] According to this embodiment, the sealing method for the tube container 100 comprises a spout 2 having a cylindrical spout 3 and a flange 4 connected to one end 6a of the spout 3 and extending outward from the spout 3, and a tubular body 1 made of a sheet 41, with a back-sealed portion 7 formed extending from one end 5a to the other end 5b, with one end 5a closed and the spout 2 attached to the other end 5b, and the sealing method for the tube container 100 which contains contents, comprising: a first heating step S4 in which the inner surface 7b of one end 7a of the back-sealed portion 7 and the inner surface 9a of the opposing portion 9 facing the one end 7a of the back-sealed portion 7 of the body 1 which has the back-sealed portion 7 formed and the spout 2 attached to the other end 5b and is filled with contents, and a second heating step S5 in which one end 5a of the body 1 including one end 7a of the back-sealed portion 7 and the opposing portion 9 is closed by heat sealing. Therefore, in the first heating step S4, the inner surface 7b of one end 7a of the back-sealed portion 7 and the inner surface 9a of the opposing portion 9, where multiple films overlap, are preheated to preheat the inner surface 7a of one end of the back-sealed portion 7 and the inner surface 9a of the opposing portion 9, and then in the second heating step S5, the entire one end 5a of the body portion 1 can be heat-sealed. Thus, even though the heat capacity of the first closed portion 10a, which is formed by one end 7a of the back-sealed portion 7 and the opposing portion 9 of the closed portion 10, is greater than the heat capacity of the second closed portion 10b, which is the portion of the closed portion 10 that does not include one end 7a of the back-sealed portion 7 and the opposing portion 9, the temperature difference between the temperature of the inner surface 1a of the sheet 41 in the first closed portion 10a and the temperature of the inner surface 1a of the sheet 41 in the second closed portion 10b can be reduced in the second heating step S5. Therefore, variations in the sealing strength of the first closure portion 10a and the second closure portion 10b can be suppressed, thereby increasing the overall sealing strength of the closure portion 10. Furthermore, since it is possible to suppress the temperature of the second closure portion 10b from becoming too high, it is possible to suppress thermal deformation of the second closure portion 10b due to overheating, and to suppress the trapping of air bubbles in the second closure portion 10b.

[0046] According to this embodiment, in the first heating step S4, hot air HA is blown onto the inner surface 7b of one end 7a of the back-sealed portion 7 and the inner surface 9a of the opposing portion 9. Therefore, in the first heating step S4, the inner surface 7b of one end 7a of the back-sealed portion 7 and the inner surface 9a of the opposing portion 9 can be directly heated. As a result, compared to the case where the outer surface of one end 7a of the back-sealed portion 7 and the outer surface of the opposing portion 9 are heated separately, the temperature of the inner surface 7b of one end 7a of the back-sealed portion 7 and the temperature of the inner surface 9a of the opposing portion 9 can be brought more favorably closer to their respective target temperatures. Consequently, in the second heating step S5, fluctuations in the temperature of the inner surface 1a of the sheet 41 in the first closure portion 10a can be suppressed, and the temperature difference between the temperature of the inner surface 1a of the sheet 41 in the first closure portion 10a and the temperature of the inner surface 1a of the sheet 41 in the second closure portion 10b can be more favorably reduced. Therefore, variations in the sealing strength of the first closure portion 10a and the second closure portion 10b can be more effectively suppressed, thereby more effectively increasing the overall sealing strength of the closure portion 10, and also more effectively suppressing thermal deformation of the second closure portion 10b and the trapping of air bubbles in the second closure portion 10b.

[0047] According to this embodiment, in the second heating step S5, the entire outer surface of one end 5a of the body portion 1 is heated while the inner surfaces of the two ends 5a of the body portion 1 are brought into contact with each other. Therefore, temperature variations throughout the entire closure portion 10 can be suppressed, and thus variations in the seal strength of the entire closure portion 10 can be suppressed.

[0048] In this embodiment, the thickness of the sheet 41 is 100 μm or more. Furthermore, in this embodiment, as described above, in the first heating step S4, the inner surface 7b of one end 7a of the back-sealed portion 7 that forms the first closure portion 10a and the inner surface 9a of the opposing portion 9 are preheated, and then in the second heating step S5, the entire one end 5a of the body portion 1 is heat-sealed. Therefore, because the thickness of the sheet 41 constituting the body portion 1 is 100 μm or more, even if the difference between the heat capacity of the first closure portion 10a and the heat capacity of the second closure portion 10b is large, the temperature difference between the temperature of the inner surfaces 7b and 9a of the sheet 41 in the first closure portion 10a and the temperature of the inner surface 1a of the sheet 41 in the second closure portion 10b can be suitably reduced in the second heating step S5. Therefore, variations in the sealing strength of the first closure portion 10a and the second closure portion 10b can be more effectively suppressed, thereby more effectively increasing the overall sealing strength of the closure portion 10, and also more effectively suppressing thermal deformation of the second closure portion 10b and the trapping of air bubbles in the second closure portion 10b.

[0049] As mentioned above, in this embodiment, one end 5a of the body portion 1 is sealed by heat sealing, but it is also conceivable to seal one end 5a of the body portion 1 by ultrasonic welding. However, when ultrasonic welding is performed, if ultrasonic welding is carried out to achieve an appropriate seal strength between one end 7a of the back sealing portion 7 and the opposing portion 9, the thickness of the back sealing portion 7 makes it easy for the outer layer of one end 7a of the back sealing portion 7 to tear. On the other hand, in this embodiment, in which one end 5a of the body portion 1 is heat-sealed by the first heating step S4 and the second heating step S5, it is possible to suppress the temperature of one end 7a of the back sealing portion 7 from becoming too high, and thus it is possible to suppress the tearing of the outer layer of one end 7a of the back sealing portion 7.

[0050] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the spirit of the present invention are also included. Furthermore, the components shown in the above-described embodiment and the following modifications can be combined as appropriate.

[0051] The back-sealed portion is not limited to the configuration of this embodiment, which is formed by overlapping and sealing the inner surfaces of one edge of the sheet with the inner surfaces of the other edge of the sheet in a girdle shape. The back-sealed portion may also be formed, for example, by facing the inner surface of one edge of the sheet with the outer surface of the other edge of the sheet, and overlapping and sealing the two edges. In this case, the back-sealed portion is formed by overlapping two sheets, and the first closing portion of the closing portion is formed by overlapping three sheets. Even in this case, by appropriately setting the target temperature of the inner surface of one end of the back-sealed portion and the target temperature of the inner surface of the opposing portion in the first heating step, it is possible to increase the overall seal strength of the closing portion 10 while suppressing thermal deformation of the second closing portion due to overheating and the trapping of air bubbles in the second closing portion.

[0052] The layer structure of the sheet forming the body is not limited to this embodiment. For example, the sheet does not have to have a paper layer and a paper protective layer. In this case, the physical strength of the sheet and the body can be ensured by increasing the thickness of the base film layer, etc. [Explanation of symbols]

[0053] 1 Torso 2 Spout part 3 Dispensing tube part 4. Flange section 5a One end 5b other end 6a One end of the dispensing cylinder 7. Back seal section 9 Opposite part 41 sheets 100 tube containers HA Hot Air S4 1st heating process S5 2nd heating process

Claims

1. A dispensing port having a cylindrical dispensing tube and a flange connected to one end of the dispensing tube and extending outward from the dispensing tube, It consists of a sheet, with a back-sealed portion extending from one end to the other, a tubular body portion with one end closed and the spout portion attached to the other end, A method for sealing a tube container that contains contents, comprising: A first heating step involves heating the inner surface of one end of the back-sealed portion and the inner surface of the opposing portion, respectively, in a state where the inner surface of one end of the back-sealed portion of the body, which has the back-sealed portion formed and the spout portion attached to the other end, and the inner surface of the opposing portion facing the one end of the back-sealed portion is separated from each other. A method for sealing a tube container, comprising a second heating step of closing one end of the back-sealed portion and one end of the body portion including the opposing portion by heat sealing.

2. The method for sealing a tube container according to claim 1, wherein in the first heating step, hot air is blown onto the inner surface of one end of the back-sealed portion and the inner surface of the opposing portion, respectively.

3. A method for sealing a tube container according to claim 1 or 2, wherein in the second heating step, the entire outer surface of one end of the body is heated while the inner surfaces of the two ends of the body are brought into contact with each other.

4. The method for sealing a tube container according to claim 1, wherein the thickness of the sheet is 100 μm or more.

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