Plug welding method

Abstract

To suppress occurrence of tearing of a film at a welded lower edge of a plug.SOLUTION: There is provided a plug welding method for welding a resin plug 3 to a body film 4 of a pouch body 2, comprising: a protrusion forming process in which a heated mold 40 is used to melt a welding surface 36 of a welding portion 33 to form a plurality of ribs 37 on the welding surface 36; and a welding process in which the body film 4 is brought into contact with the welding surface 36 in a state in which a temperature of the welding surface 36 heated in the protrusion forming process is equal to or higher than a melting point of the welding portion 33, and the body film 4 is pressed against the welding portion 33 to crush the ribs 37 while welding the body film 4 and the welding surface 36 to each other.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a plug welding method for welding a resin plug to a film of a pouch body. [Background technology]

[0002] Conventionally, as a container for accommodating contents such as liquid, a pouch with a stopper has been used in which a plurality of films are heat-sealed at predetermined locations to form a bag shape, and a resin stopper is heat-sealed to the films (see, for example, Patent Document 1). This stopper has a flow path extending in a first direction, a pouring portion extending in the first direction to form a part of the flow path, and a welding portion extending in the first direction to form another part of the flow path. The welding portion of the stopper is disposed between a pair of films, and the stopper is heat-sealed to the films, thereby attaching the stopper to the pair of films. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-523858 Summary of the Invention [Problem to be solved by the invention]

[0004] When welding a film to the welding surface of the welding part of the plug, the film is overlapped on the welding part of the plug, and the film is pressed onto the welding surface of the welding part while being heated with a seal bar. At that time, stress is likely to concentrate on the film at the lower end edge of the welding part of the welding part, and the film may become thin. The lower end edge of the welding part of the welding part is the end edge of the welding surface of the welding part opposite the pouring part side. If the film becomes thin at the lower end edge of the welding part, the film becomes easily torn, and the possibility of the contents leaking out increases. Therefore, the present invention relates to a plug welding method that can suppress the occurrence of tearing of the film at the lower end edge of the welding part of the plug. [Means for solving the problem]

[0005] The spout welding method of the present invention is, [1] "a spout welding method for welding a resin spout to a film of a pouch body, wherein the spout has a flow path extending in a first direction, a pouring portion extending in the first direction to form a part of the flow path, and a welding portion extending in the first direction to form another part of the flow path and having a welding surface on its surface to which the film is welded, the spout welding method including: a convex portion forming step of melting the welding surface using a heated mold to form a plurality of convex portions on the welding surface; and a welding step of bringing the film into contact with the welding surface in a state in which the temperature of the welding surface heated in the convex portion forming step is equal to or higher than the melting point of the welding portion, and pressing the film against the welding portion to crush the convex portions while welding the film and the welding surface to each other."

[0006] In this plug welding method, the film is brought into contact with the welding surface in a state where the temperature of the welding surface of the welding part heated in the convex part forming step is equal to or higher than the melting point of the welding part. In other words, the film is brought into contact with the welding surface before the temperature of the convex part formed in the convex part forming step falls below the melting point. Then, the film is pressed against the convex part, and the film and the welding surface are welded to each other while crushing the convex part. At this time, the film is pressed against the convex part, and the molten convex part is crushed. The resin of the crushed convex part spreads over a wide range of the welding surface. In this way, the film is first received by the molten convex part, and then received and welded by the entire welding surface of the welding part. In this way, the film is suppressed from being pressed against the lower end edge of the welding part from the early stage of the welding step, and the film is suppressed from becoming thin at the lower end edge of the welding part. As a result, in this plug welding method, it is possible to suppress the occurrence of tearing of the film at the lower end edge of the welding part of the plug.

[0007] The above-mentioned plug welding method may be [2] "the plug welding method according to the above-mentioned [1], in which in the convex portion forming step, the welding surface is heated by the mold to form the convex portion so that the temperature of the welding surface is equal to or higher than the melting point of the welding portion and the wall surface of the flow path in the welding portion is lower than the melting point of the welding portion." In this case, the plug welding method can form a convex portion on the welding surface of the welding portion of the plug while maintaining the shape of the flow path.

[0008] The above spout welding method may be [3] "the spout welding method according to the above [1] or [2], in which in the convex portion forming step, a rib extending in a direction perpendicular to the first direction is formed as the convex portion." Here, the film first abuts against the rib. Therefore, the portion of the welding portion where the rib is provided is more reliably welded to the film. For example, when poor welding occurs, the contents in the pouch body move along the first direction between the welding surface of the welding portion and the film and tend to leak out. Therefore, in this spout welding method, the rib that is more reliably welded extends in a direction perpendicular to the first direction and is welded to the film, so that the path through which the contents leak out can be blocked. In this way, this spout welding method can further suppress the contents in the pouch body from leaking out to the outside.

[0009] The above-mentioned spout welding method may be [4] "the spout welding method according to the above-mentioned [1] or [2], in which in the convex portion forming step, a rib extending parallel to the lower end edge of the welded portion, which is the end edge of the welded surface opposite to the pouring portion side, is formed as the convex portion." In this case, when the film is pressed against the welded portion, the rib extending along the lower end edge of the welded portion receives the film first. Therefore, the film is prevented from contacting the lower end edge of the welded portion from an early stage of the welding step. As a result, in the spout welding method, it is possible to prevent the film from becoming thin at the lower end edge of the welded portion of the spout, and to further prevent the film from breaking.

[0010] The above-mentioned spout welding method may be [5] "the spout welding method according to the above-mentioned [4], in which in the convex portion forming step, the rib is formed so that a convex portion non-formed portion is provided adjacent to the lower end edge of the welded portion, and the convex portion non-formed portion is a portion where the rib is not formed." In this case, when the film is pressed against the rib in the welding step, the resin of the crushed rib spreads to the convex portion non-formed portion. In the later stage of the welding step after the rib is crushed, the portion of the film adjacent to the lower end edge of the welded portion is received and welded by the convex portion non-formed portion. In this way, the spout welding method can suppress the film from being pressed against the lower end edge of the welded portion from the early stage of the welding step. This can suppress the film from becoming thin at the lower end edge of the welded portion of the spout, and further suppress the occurrence of film tearing.

[0011] The above-mentioned spout welding method may be [6] "the spout welding method according to any one of the above-mentioned [1] to [5], wherein the height positions of the apexes of the plurality of protrusions are the same." In this case, in the spout welding method, when the film is pressed against the plurality of protrusions, the film is received by the plurality of protrusions. That is, the stress applied to the film is dispersed. As a result, in the spout welding method, it is possible to prevent the film from becoming thin at the welded portion. Effect of the Invention

[0012] According to the present invention, the occurrence of tearing of the film at the lower edge of the welded portion of the plug can be suppressed. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a front view showing a spouted pouch according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 3 is a perspective view showing the plug in a state before it is welded. [Figure 4]FIG. 4 is a view of the plug being clamped by the metal mold in the convex portion forming step, as viewed from the bottom side. [Diagram 5] FIG. 5 is a side view of the plug being clamped by the metal mold in the convex portion forming step. [Figure 6] FIG. 6 is a side view of the plug sandwiched between the dies in the protruding portion forming step. [Figure 7] FIG. 7 is a front view of the plug with the ribs formed in the protrusion forming step. [Figure 8] FIG. 8 is an enlarged cross-sectional view showing a state in which the body film is brought into contact with the welding portion in the welding step. [Figure 9] 9(a) to 9(c) are enlarged cross-sectional views showing how the ribs are crushed and the body film is welded to the welded portion in the welding process. [Figure 10] FIG. 10 is a table showing the evaluation test results of the spouted pouches. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0015] (Pouch with spout) The spouted pouch 1 shown in Fig. 1 is used, for example, for packaging refill contents, beverage packaging, cosmetic packaging, etc. As shown in Figs. 1 and 2, the spouted pouch 1 comprises a pouch body 2 and a spout 3. The pouch body 2 comprises a first body film (film) 4A and a second body film (film) 4B arranged to face each other, and a folding film 5 folded between the first body film 4A and the second body film 4B. Note that the pouch body 2 may not comprise the folding film 5, or may further comprise another film.

[0016] In the spouted pouch 1, the first body film 4A and the second body film 4B are welded (thermally welded) to each other at their outer edges, and the first body film 4A and the second body film 4B are welded to each other at their outer edges, so as to form a storage area 6 for storing contents inside the spouted pouch 1. A spout 3 is disposed between the first body film 4A and the second body film 4B, and the outer edges of the first body film 4A and the second body film 4B are welded to the spout 3. The first body film 4A and the second body film 4B have the same shape, structure, etc., and are welded to the spout 3, so that hereinafter, the first body film 4A and the second body film 4B will be collectively described as body film (film) 4, unless otherwise specifically described separately.

[0017] The body film 4 is formed of a laminated sheet in which a base layer 7 and a sealant layer 8 are laminated together. The laminated sheet constituting the body film 4 may include layers other than the base layer 7 and the sealant layer 8.

[0018] The base layer 7 provides a predetermined rigidity to the body film 4 and has a barrier property that prevents the passage of gas and liquid. The material of the base layer 7 is not particularly limited, but can be, for example, polyolefin (e.g., polyethylene, very low density polyethylene, low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, or polypropylene) or polyester (e.g., polyethylene terephthalate).

[0019] The sealant layer 8 is a layer that can be melted by heat and welded to another member. The material of the sealant layer 8 is not particularly limited, but can be, for example, polyolefin (e.g., polyethylene, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, polypropylene, or ionomer polyethylene), ethylene-acrylic copolymer, ethylene glycol-methacrylic acid copolymer, or ethylene-vinyl acetate copolymer.

[0020] The contents accommodated in the accommodation area 6 of the spouted pouch 1 are not particularly limited, but are preferably liquids. Examples of the contents include daily necessities such as liquid detergents, cleaning agents, medicines, cosmetics, shampoos, and conditioners, liquid seasonings, foods such as soups, yogurt, soft drinks, and edible oils, and industrial products such as lubricating oils and industrial oils. The spouted pouch 1 may be a pouch with a contents inlet plug in which the contents are accommodated in the accommodation area 6.

[0021] The plug 3 is a resin member welded to the body film 4. The material of the plug 3 is not particularly limited, but may be, for example, a polymer composition, and is preferably made of polyolefin (e.g., high density polyethylene, polypropylene), and more preferably made of high density polyethylene from the viewpoint of ease of molding.

[0022] The spout 3 has a flow path 31 for circulating the contents contained in the pouch body 2, an outlet portion 32 arranged on the outside of the pouch body 2 and forming part of the flow path 31, a welded portion 33 welded to the body film 4 and forming another part of the flow path 31, and a flange portion 34 located between the outlet portion 32 and the welded portion 33.

[0023] (Plug) The plug 3 shown in Fig. 3 is in a state before being welded to the body film 4. The plug is also called a spout, etc. As shown in Fig. 3, the plug 3 includes a flow path 31, a pouring portion 32, a welded portion 33, and a flange portion 34.

[0024] The flow path 31 extends in a first direction D1 and penetrates the spout 3 to allow the content contained in the containing area 6 of the spouted pouch 1 to flow. In other words, the flow path 31 is a hole defined by the inner circumferential surfaces of the pouring portion 32, the welded portion 33, and the flange portion 34, and is a through hole that penetrates the spout 3 in the first direction D1.

[0025] The spouting portion 32 is disposed on the outside of the pouch body 2 of the spouted pouch 1, and is a portion for pouring out the contents contained in the storage area 6 of the spouted pouch 1. The spouting portion 32 extends in a first direction D1, and forms a part of the flow path 31. The spouting portion 32 is formed in a cylindrical shape. The flow path 31 is formed on the inner peripheral surface of the spouting portion 32, and a screw thread 32a is formed on the outer peripheral surface of the spouting portion 32 for detachably attaching a cap (not shown). The cap is a member that closes the flow path 31 in an openable and closable manner.

[0026] The welded portion 33 is a portion that is welded to the body film 4. In other words, the welded portion 33 is disposed between the first body film 4A and the second body film 4B, and is a portion that is welded to the first body film 4A and the second body film 4B. The welded portion 33 extends in the first direction D1 and forms another part of the flow path 31.

[0027] The flange portion 34 is a flange-shaped portion located between the pouring portion 32 and the welded portion 33. The flange portion 34 is disposed on the outer side of the pouch body 2 of the spouted pouch 1, and extends in a direction perpendicular to the first direction D1. The flange portion 34 is used, for example, to position the welded portion 33 relative to the body film 4. Note that, although only one flange portion 34 is provided in this embodiment, a plurality of flange portions 34 may be provided in the first direction D1.

[0028] As shown in Figs. 3 and 4, the welded portion 33 has a first welded surface (welded surface) 36A welded to the first body film 4A and a second welded surface (welded surface) 36B (see Fig. 4) welded to the second body film 4B. The welded portion 33 has a cross section perpendicular to the first direction D1 that is substantially rhombic. That is, the welded portion 33 is wider in a third direction D3 perpendicular to the first direction D1 and the second direction D2 than in a second direction D2 perpendicular to the first direction D1. The first welded surface 36A and the second welded surface 36B are positioned to face the second direction D2 and are connected to each other at both ends in the third direction D3 at an acute angle. Since the first welded surface 36A and the second welded surface 36B have the same shape, structure, etc., the first welded surface 36A and the second welded surface 36B will be collectively described as the welded surface 36 below unless otherwise specified.

[0029] Next, a plug welding method for welding the resin plug 3 to the body film 4 of the pouch body 2 will be described. In the plug welding method according to this embodiment, first, a convex portion forming step is performed to form a plurality of ribs on the welding portion 33 of the plug 3 shown in Fig. 3. Then, a welding step is performed to weld the body film 4 to the welding portion 33 of the plug 3.

[0030] (Convex forming process) First, the convex portion forming step will be described. As shown in Fig. 4 to Fig. 6, in the convex portion forming step, a heated metal mold (die) 40 is used to melt the welded portion 33 and form a plurality of ribs (convex portions) 37 (see Fig. 6) on the welded surface 36. More specifically, the metal mold 40 includes a first die 41 and a second die 42. The first die 41 and the second die 42 are heated by a heater (not shown). The first welded surface 36A and the second welded surface 36B of the welded portion 33 are sandwiched between the first die 41 and the second die 42.

[0031] The first mold 41 has a first molding surface 41a that is brought into contact with the first welding surface 36A of the welding portion 33. The first molding surface 41a has a shape that conforms to the shape of the first welding surface 36A. The first molding surface 41a is provided with a plurality of first grooves 41b extending along the third direction D3. The plurality of first grooves 41b have the same groove depth. The plurality of first grooves 41b are aligned in the first direction D1. In this embodiment, three first grooves 41b are provided. Similarly, the second mold 42 has a second molding surface 42a that is brought into contact with the second welding surface 36B of the welding portion 33. The second molding surface 42a has a shape that conforms to the shape of the second welding surface 36B. The second molding surface 42a is provided with a plurality of second grooves 42b extending along the third direction D3. The plurality of second grooves 42b have the same groove depth. The second grooves 42b are aligned in the first direction D1. In the present embodiment, three second grooves 42b are provided.

[0032] 6, in the convex portion forming step, the weld portion 33 of the plug 3 is sandwiched between heated first and second molds 41 and 42 from the second direction D2. At that time, the weld portion 33 is sandwiched between the first and second molds 41 and 42 so that the first molding surface 41a of the first mold 41 abuts against the first welding surface 36A of the weld portion 33 and the second molding surface 42a of the second mold 42 abuts against the second welding surface 36B of the weld portion 33. The first and second molds 41 and 42 heat the weld portion 33 until the temperature reaches or exceeds the melting point of the weld portion 33, causing the weld portion 33 to melt.

[0033] In the protrusion forming process, the welded portion 33 is heated so that the temperature of the welded surface 36 of the welded portion 33 is equal to or higher than the melting point of the welded portion 33, and the wall surface of the flow path 31 in the welded portion 33 is lower than the melting point of the welded portion 33. In other words, the periphery of the welded surface 36 of the welded portion 33 is heated to the melting point or higher in order to form the rib 37. On the other hand, in order to maintain the shape of the flow path 31 inside the welded portion 33, the welded portion 33 is heated so that the wall surface of the flow path 31 does not become equal to or higher than the melting point of the welded portion 33.

[0034] With the welding surface 36 of the welding portion 33 molten, the first mold 41 and the second mold 42 further sandwich the welding portion 33, so that the molten resin enters the first groove 41b and the second groove 42b. The resin that has entered the first groove 41b and the second groove 42b respectively forms a plurality of ribs 37. Then, the sandwiching by the first mold 41 and the second mold 42 is released. As a result, as shown in FIG. 7, the ribs 37 are formed on the first welding surface 36A and the second welding surface 36B of the welding portion 33, respectively (see FIG. 6 for the ribs 37 formed on the second welding surface 36B).

[0035] The first groove 41b and the second groove 42b provided in the first mold 41 and the second mold 42 respectively extend in the third direction D3. Therefore, the ribs 37 formed on the first welding surface 36A and the second welding surface 36B extend in the third direction D3. In this manner, in the protrusion forming step, the mold 40 is used to form the ribs 37 extending in the third direction D3.

[0036] 7, an edge of the welding surface 36 of the welding portion 33 on the opposite side to the pouring portion 32 side is referred to as the lower end edge 33a of the welding portion. The lower end edge 33a of the welding portion 33 extends in the third direction D3. In other words, the extending direction of the rib 37 and the extending direction of the lower end edge 33a of the welding portion 33 are the same. Thus, in the convex portion forming step, the rib 37 extending parallel to the lower end edge 33a of the welding portion 33 is formed.

[0037] Further, a portion of the welding surface 36 of the welding portion 33 where the rib 37 is not formed is referred to as a non-formed protruding portion 33b. The non-formed protruding portion 33b is a portion that does not have a shape that protrudes outward on the welding surface 36. In the protruding portion forming step, the rib 37 is formed so that the non-formed protruding portion 33b is provided adjacent to the lower end edge 33a of the welding portion 33. In other words, the rib 37 closest to the lower end edge 33a of the welding portion 33 is formed at a position spaced a predetermined length from the lower end edge 33a of the welding portion 33 in the first direction D1.

[0038] The first grooves 41b formed in the first molding surface 41a of the first mold 41 have the same groove depth. Therefore, the ribs 37 formed in the first welding surface 36A have the same height positions of their tops. Similarly, the second grooves 42b formed in the second molding surface 42a of the second mold 42 have the same groove depth. Therefore, the ribs 37 formed in the second welding surface 36B have the same height positions of their tops.

[0039] The rib 37 formed on the welding surface 36 of the welding portion 33 remains in a molten state for a predetermined period of time after the clamping by the first mold 41 and the second mold 42 is released. Even in the molten state, the rib 37 maintains its shape to some extent due to the viscosity of the resin.

[0040] In this manner, in the protrusion forming step, the rib 37 of the above-described embodiment is formed on the welding surface 36 of the welding portion 33. That is, the first groove 41b and the second groove 42b are provided in the first mold 41 and the second mold 42 so that the rib 37 of the above-described embodiment is formed.

[0041] As an example, the resin constituting the plug 3 is polyethylene. In this case, in the protruding portion forming step, as an example, the rib 37 can be formed by heating and compressing the welded portion 33 of the plug 3 for about 1 second using a mold 40 heated to 200°C.

[0042] (Welding process) Next, the welding process will be described. In the welding process, as shown in Fig. 8, the welding portion 33 of the spout 3 is disposed between the first body film 4A and the second body film 4B. Then, the first body film 4A and the second body film 4B are pressed by a heated seal bar 9, so that the first body film 4A and the second body film 4B are brought into contact with the first welding surface 36A and the second welding surface 36B of the welding portion 33, respectively. Note that Fig. 8 shows only the first welding surface 36A side of the welding portion 33.

[0043] In the welding step, the first and second body films 4A and 4B are brought into contact with the first and second welding surfaces 36A and 36B, respectively, in a state in which the temperature of the welding surface 36 of the welding portion 33 heated in the protrusion forming step is equal to or higher than the melting point of the welding portion 33. In other words, before the ribs 37 formed in the protrusion forming step harden, the first and second body films 4A and 4B are brought into contact with the ribs 37 that are still in a molten state.

[0044] The first welding surface 36A and the second welding surface 36B each have a rib 37 formed thereon. Therefore, when the first body film 4A is brought into contact with the first welding surface 36A, the first body film 4A first comes into contact with the tops of the ribs 37 provided on the first welding surface 36A. Similarly, when the second body film 4B is brought into contact with the second welding surface 36B, the second body film 4B first comes into contact with the tops of the ribs 37 formed on the second welding surface 36B.

[0045] After the first and second body films 4A and 4B are brought into contact with each other, the seal bar 9 presses the first and second body films 4A and 4B against the first and second welding surfaces 36A and 36B, respectively. Here, the first body film 4A and the first welding surface 36A are brought into close contact with each other while crushing the ribs 37 formed on the first welding surface 36A. At that time, as shown in Figs. 9(a) to 9(c), the resin of the crushed ribs 37 flows onto the surface of the convex non-forming portion 33b. Similarly, the second body film 4B and the second welding surface 36B are brought into close contact with each other while crushing the ribs 37 formed on the second welding surface 36B. After the body film 4 and the welding surface 36 are brought into close contact with each other for a predetermined time, the pressure by the seal bar 9 is released.

[0046] Here, after the convex portion forming step is completed, for example, the first and second cylinder films 4A and 4B are brought into contact with the first and second welding surfaces 36A and 36B, respectively, within about 1 second. This allows the first and second cylinder films 4A and 4B to be brought into contact with the molten ribs 37. Then, the first and second cylinder films 4A and 4B are pressed against the first and second welding surfaces 36A and 36B by the seal bar 9, for example, for about 0.6 seconds. Here, pressing the cylinder films 4 with a weak force over a period of time allows for strong welding.

[0047] Thereafter, the resin on the surfaces of the first welding surface 36A and the second welding surface 36B hardens, whereby the welding portion 33 is welded to the body film 4, thereby forming the pouch 1 with the spout described above.

[0048] As described above, in this plug welding method, the body film 4 is brought into contact with the welding surface 36 of the welding portion 33 of the plug 3 heated in the convex portion forming step while the temperature of the welding surface 36 of the welding portion 33 is at or above the melting point of the welding portion 33. In other words, the body film 4 is brought into contact with the welding surface 36 of the welding portion 33 before the temperature of the rib 37 formed in the convex portion forming step falls below the melting point. Then, the body film 4 is pressed against the body film 4, crushing the rib 37 while bringing the body film 4 and the welding surface 36 of the welding portion 33 into close contact with each other and welding them together.

[0049] At this time, as shown in Figs. 9(a) to 9(c), the first body film 4A is pressed against the ribs 37 formed on the first welding surface 36A, and the molten ribs 37 are crushed. The resin of the crushed ribs 37 flows onto the surface of the convex non-forming portion 33b and spreads over a wide range of the first welding surface 36A. In this way, the first body film 4A is first received by the molten ribs 37, and then the entire first welding surface 36A is received and welded to the first welding surface 36A. Similarly, the second body film 4B is first received by the molten ribs 37, and then the entire second welding surface 36B is received and welded to the second welding surface 36B. In this way, the body film 4 is prevented from being pressed against the lower end edge 33a of the welding portion from an early stage of the welding process, and the body film 4 is prevented from becoming thin at the lower end edge 33a of the welding portion. As a result, in this plug welding method, the occurrence of tearing of the body film 4 at the lower end edge 33a of the welded portion of the plug 3 can be suppressed.

[0050] In the early stages of the welding process, the body film 4 is brought into contact with the tops of the ribs 37. However, because the ribs 37 are in a molten state, even when the body film 4 is brought into contact with the ribs 37, stress is prevented from concentrating at the tops of the ribs 37 on the body film 4. This prevents the body film 4 from becoming thin at the tops of the ribs 37, and prevents the body film 4 from tearing.

[0051] In the protrusion forming step, the welded portion 33 is heated by the mold 40 to form the rib 37 so that the temperatures of the first welded surface 36A and the second welded surface 36B of the welded portion 33 are higher than the melting point of the welded portion 33 and the wall surface of the flow path 31 inside the welded portion 33 is lower than the melting point of the welded portion 33. In this case, in this spout welding method, the rib 37 can be formed on the welded surface 36 of the welded portion 33 while maintaining the shape of the flow path 31.

[0052] The rib 37 formed on the welding surface 36 extends in a third direction D3 perpendicular to the first direction D1. Here, the body film 4 first comes into contact with the rib 37 in the welding process. Therefore, the portion of the welding part 33 where the rib 37 is provided is more reliably welded to the body film 4. For example, if poor welding occurs, the contents in the pouch body 2 move between the welding part 33 and the body film 4 along the first direction D1 and tend to leak out. In this spout welding method, the rib 37, which is more reliably welded, extends in the third direction D3 perpendicular to the first direction D1 and is welded to the film, thereby blocking the path through which the contents leak out. In this manner, this spout welding method can further prevent the contents in the pouch body 2 from leaking out to the outside.

[0053] The rib 37 extends parallel to the lower end edge 33a of the welded portion 33. In this case, when the body film 4 is pressed against the welding surface 36 of the welded portion 33, the rib 37 extending along the lower end edge 33a of the welded portion receives the body film 4 first. This prevents the body film 4 from contacting the lower end edge 33a of the welded portion 33 from an early stage of the welding process. This prevents the body film 4 from becoming thin at the lower end edge 33a of the welded portion of the spout 3, and further prevents the body film 4 from tearing.

[0054] In the convex portion forming step, a convex portion non-forming portion 33b where the rib 37 is not formed is provided adjacent to the lower end edge 33a of the welding portion 33. In this case, when the body film 4 is pressed against the rib 37 in the welding step, the resin of the crushed rib 37 spreads to the convex portion non-forming portion 33b. In the later stage of the welding step after the rib 37 is crushed, the portion of the body film 4 near the lower end edge 33a of the welding portion 33 of the welding portion 33 is received and welded by the convex portion non-forming portion 33b. In this way, this spout welding method can prevent the body film 4 from being pressed against the lower end edge 33a of the welding portion 33 from the early stage of the welding step. As a result, this spout welding method can prevent the body film 4 from becoming thin at the lower end edge 33a of the welding portion of the spout 3, and can further prevent the body film 4 from breaking.

[0055] The multiple ribs 37 formed on the welding surface 36 have their tops at the same height. In this case, in this spout welding method, when the body film 4 is pressed against the multiple ribs 37, the body film 4 is received by the multiple ribs 37. This distributes the stress applied to the body film 4. This makes it possible to prevent the body film 4 from becoming thin in the welding portion welded to the welding portion 33.

[0056] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the number and shape of the ribs 37 formed on the welding surface 36 of the welding portion 33 are not limited to the configuration described using Fig. 7, etc. Also, on the welding surface 36 of the welding portion 33, multiple convex portions (protruding dots) may be formed instead of multiple ribs 37.

[0057] Examples of the present invention and the results of evaluation tests thereof will be described below, but the present invention is not limited to the following examples. The following materials were used to prepare a spouted pouch according to the embodiment. (Example) -Pouch body film composition Base layer: 2-layer structure of HDPE#30 and HDPE#32 Sealant layer: LLDPE#100 · Spout…12 Unilock spout ribless (Nippon Closure Co., Ltd.) -Mold used (with grooves) As described above, in the spouted pouch of the embodiment, the rib was formed by melting the welded portion of the spout using a grooved mold, and while the rib was in the melted state, the body film was abutted against the welded portion to weld the pouch body and the spout.

[0058] For comparison, spouted pouches according to Comparative Examples 1 and 2 were produced. Comparative Example 1 -Pouch body film composition Base layer: 2-layer structure of HDPE#30 and HDPE#32 Sealant layer: LLDPE#100 · Spout…12 Unilock spout ribless (Nippon Closure Co., Ltd.) · Mold used (without groove) In the spouted pouch of Comparative Example 1, the spout was the same as in the Examples, but the welding part of the spout was melted using a mold without a groove, and then the body film was brought into contact with the welding part to weld the pouch body and the spout. In other words, in Comparative Example 1, the molten ribs in the Examples were not formed.

[0059] Comparative Example 2 -Pouch body film composition Base layer: 2-layer structure of HDPE#30 and HDPE#32 Sealant layer: LLDPE#100 · Spout…12NC flap spout (Nippon Closure Co., Ltd.) · Mold used (without groove) A spouted pouch according to Comparative Example 2 used a spout that originally had a rib at the welding portion. In Comparative Example 2, the welding portion of the spout was melted using a mold that had no groove, as in Comparative Example 1, and then the body film was brought into contact with the welding portion to weld the pouch body and the spout. In other words, in Comparative Example 2, the molten rib as in the Examples was not formed.

[0060] As evaluation tests for spouted pouches, a pressure test and a bag drop test were conducted. In the pressure test, 160 ml of liquid at 50°C was sealed in the spouted pouch, and a load of 80 kg was applied for 3 minutes. In the pressure test, 10 spouted pouches were tested to evaluate the presence or absence of leakage from the welded part between the spout and the pouch body. In the bag drop test, 160 ml of liquid at 5°C was sealed in the spouted pouch, and the spouted pouch was dropped from a height of 1 m in a horizontal position (with the first body film facing down and the second body film facing up). In the bag drop test, 10 spouted pouches were tested to evaluate the presence or absence of tearing (bag breakage) in the welded part between the spout and the pouch body. In the pressure test and the bag drop test, the temperature conditions of the mold for melting the welded part of the spout were changed, and each test was conducted. Here, the tests were performed with the die temperatures set to 230°C, 200°C, and 170°C.

[0061] The evaluation test results are shown in Figure 10. In the spouted pouches according to the embodiment, no leaks occurred in the pressure test regardless of the temperature of the mold, and no breaks occurred in the bag drop test. On the other hand, in the spouted pouches according to comparative examples 1 and 2, some leaks occurred in the pressure test. Also, in the spouted pouches according to comparative examples 1 and 2, some leaks occurred in the pressure test depending on the temperature conditions of the mold.

[0062] In Comparative Example 1, when the mold temperature was 230°C, some resin pools occurred at the lower edge of the welded part of the plug. In Comparative Example 1, when the mold temperature was 170°C, some sealing defects (welding defects) occurred on the welded surface of the plug.

[0063] In Comparative Example 2, when the mold temperature was 230°C, some resin pools occurred at the lower edge of the welded portion of the plug, and some of the body film was torn at the lower edge of the welded portion. In Comparative Example 2, when the mold temperature was 200°C, some of the plugs leaked from the sides of the welded portion. In Comparative Example 2, when the mold temperature was 170°C, some of the body film was torn on the original rib on the welded surface of the plug.

[0064] In this way, it was found that the spouted pouch according to the embodiment, which was produced by the above-mentioned convex portion forming process and welding process, is superior to a spouted pouch to which these processes were not applied. [Explanation of symbols]

[0065] 2...pouch body, 3...stopper, 4...body film (film), 4A...first body film (film), 4B...second body film (film), 31...flow path, 32...pouring portion, 33...welded portion, 33a...lower edge of welded portion, 33b...non-molded portion of convex portion, 36...welded surface, 36A...first welded surface (welded surface), 36B...second welded surface (welded surface), 37...rib (convex portion), D1...first direction.

Claims

1. A method for welding a resin plug to a film of a pouch body, comprising the steps of: The plug is A flow path extending in a first direction; A pouring portion extending in the first direction and forming a part of the flow path; a welding portion extending in the first direction to form another part of the flow path and having a welding surface to which the film is welded, a protrusion forming step of melting the welding surface using a heated mold to form a plurality of protrusions on the welding surface; a welding step of bringing the film into contact with the welding surface in a state in which the temperature of the welding surface heated in the convex portion forming step is equal to or higher than the melting point of the welding portion, and pressing the film against the welding portion to crush the convex portion and weld the film and the welding surface to each other.

2. 2. The method for welding a plug according to claim 1, wherein in the convex portion forming step, the welding surface is heated by the mold to form the convex portion so that the temperature of the welding surface is equal to or higher than the melting point of the welding portion and the wall surface of the flow path in the welding portion is lower than the melting point of the welding portion.

3. The plug welding method according to claim 1 , wherein in the convex portion forming step, a rib extending in a direction perpendicular to the first direction is formed as the convex portion.

4. 2. The method for welding a spout according to claim 1, wherein in the convex portion forming step, a rib extending parallel to a lower end edge of a welding portion, which is an end edge of the welding surface opposite to the pouring portion side, is formed as the convex portion.

5. In the protrusion forming step, the rib is formed so that a protrusion non-formed portion is provided adjacent to a lower end edge of the welded portion, 5. The method for welding a plug according to claim 4, wherein the non-projection portion is a portion where the rib is not formed.

6. The plug welding method according to any one of claims 1 to 5, wherein the plurality of protrusions have apexes at the same height position.

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