Method for producing sheet welded structure, method for producing tube container, and sheet welded structure and tube container

Abstract

To provide a sheet welded structure formed by firmly welding two sheets containing a polyester resin to each other.　In a method for producing a sheet welded structure based on the present invention, a first sheet portion SP1 having a thickness of a1 and a second sheet portion SP2 having a thickness of a2 are welded to each other. The method for producing a sheet welded structure satisfies relational expressions (1) and (2) when b is a distance in the thickness direction DT between the surface closest to the first sheet portion SP1 on a first surface M11a and the surface farthest from the first sheet portion SP1 on a second surface M11b when a first member M1 starts to press on the first sheet portion SP1 and c' is a distance in the thickness direction DT between the second surface M11b and a second pressing surface M21 when the first member M1 and a second member M2 are closest to each other during welding of the first sheet portion SP1 and the second sheet portion SP2.　

Description

Method for manufacturing a sheet welding structure and a tube container, and sheet welding structure and tube container

[0001] The present invention relates to a method for manufacturing a sheet welding structure and a tube container, as well as a sheet welding structure and a tube container.

[0002] Patent Document 1 (Japanese Patent No. 6976032) discloses a conventional tube container and a manufacturing method thereof. The tube container comprises a pouring unit and a body portion. The body portion is formed by overlapping one side edge of one side edge of a film with the other side edge of the other side edge, and the overlapped one side edge and the other side edge are welded together. An inner layer constituting the inner surface of the body portion and an outer layer constituting the outer surface of the body portion are each formed from a resin containing a non-adsorbent resin. It is disclosed that examples of the non-adsorbent resin constituting the inner layer and the outer layer include polyester-based resins and cyclic polyolefin-based resins.

[0003] The welding is carried out by heat sealing, and it is disclosed that examples of the heat sealing include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

[0004] Patent No. 6976032

[0005] For example, a tube container described in Patent Document 1 has a sheet welding structure formed by welding sheets (films) together. To improve the recyclability of such containers, such as tube containers, it has been considered to form a sheet welding structure using a sheet containing a polyester resin. However, there is room for further improvement in firmly welding sheets containing polyester resin together.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a sheet welding structure formed by firmly welding two sheets containing polyester-based resin to each other.

[0007] A method for manufacturing a sheet welding structure according to a first aspect of the present invention includes: １ a first sheet portion containing a polyester resin and having a thickness of a ２ and a second sheet portion having a shape similar to that of the first sheet portion and a second sheet portion having a shape similar to that of the first sheet portion and a second sheet portion having a shape similar to that of the second sheet portion, overlapping the first sheet portion and the second sheet portion in a thickness direction, and pressing the first sheet portion from one side in the thickness direction with a first member and pressing the second sheet portion from the other side in the thickness direction with a second member, thereby welding the first sheet portion and the second sheet portion to each other. The first member is one of an anvil and an ultrasonic horn and has a first pressing surface that presses the first sheet portion. The second member is the other of the anvil and the ultrasonic horn and has a second pressing surface that presses the second sheet portion. The first pressing surface includes one or more first surfaces and one or more second surfaces. The one or more first surfaces are arranged in a pattern when viewed from the first sheet portion when pressing by the first member begins, and include a surface that is closest to the first sheet portion. The one or more second surfaces are arranged in a pattern so as not to overlap with the first surface when viewed from the first sheet portion when the first member begins to press the first sheet portion, and include a surface that is located farther than the first surface and is farthest from the first sheet portion. When the distance in the thickness direction between the surface of the first surface closest to the first sheet portion and the surface of the second surface farthest from the first sheet portion when the first member begins to press the first sheet portion is b, and the distance in the thickness direction between the second surface and the second pressing surface when the first member and the second member are closest to each other during welding of the first sheet portion and the second sheet portion is c', the manufacturing method of a sheet welding structure satisfies the following relational expressions (1) and (2):

[0008] A sheet welding structure according to a second aspect of the present invention includes a polyester resin and has a thickness of a １ and a first sheet portion containing a polyester resin and having a thickness of a ２The sheet welding structure is formed by overlapping a second sheet portion, each of which has a shape such that the first sheet portion is located on one side in the thickness direction and the second sheet portion is located on the other side in the thickness direction, and welding the first sheet portion and the second sheet portion together. The sheet welding structure includes one or more thin-walled portions and one or more thick-walled portions. The one or more thin-walled portions are arranged in a pattern when the sheet welding structure is viewed from the one side in the thickness direction, and include portions of the sheet welding structure that are thinnest in the thickness direction. The one or more thick-walled portions are arranged in a pattern so as not to overlap the thin-walled portions when the sheet welding structure is viewed from the one side in the thickness direction, and are thicker in the thickness direction than the thin-walled portions and include portions of the sheet welding structure that are thickest in the thickness direction. When the thickness of the thickest portion of the thick-walled portion is c and the thickness of the thinnest portion of the thin-walled portion is d, the sheet welding structure satisfies the following relational expressions (5) and (6).

[0009] According to the present invention, it is possible to provide a sheet welded structure formed by firmly welding two sheets containing polyester-based resin together.

[0010] 11 is a schematic cross-sectional perspective view showing sheet portions and the like for forming a sheet welding structure according to one embodiment of the present invention. FIG. 12 is a schematic cross-sectional perspective view showing a sheet welding structure according to one embodiment of the present invention. FIG. 13 is a schematic cross-sectional view showing a first sheet portion and a second sheet portion. FIG. 14 is a flow diagram showing a manufacturing method of a sheet welding structure. FIG. 14 is a schematic cross-sectional view showing each sheet portion and the like when pressure on the first sheet portion and the second sheet portion begins. FIG. 15 is a schematic cross-sectional view showing each sheet portion and the like when pressure on the first sheet portion and the second sheet portion stops. FIG. 16 is a partial plan view of a first member viewed from the first pressing surface side. FIG. 17 is a plan view showing a first pressing surface according to a modified example. FIG. 18 is a plan view showing a first pressing surface according to another modified example. FIG. 19 is a cross-sectional view of the first member of FIG. 9 viewed in the direction of the X-X arrows. FIG. 19 is a schematic cross-sectional view showing a sheet welding structure. FIG. 19 is a plan view of a sheet welding structure according to a modified example. FIG. 19 is a plan view showing a sheet welding structure according to another modified example. FIG. 19 is a cross-sectional view of the sheet welding structure of FIG. 14 viewed in the direction of the XV-XV arrows. FIG. 19 is a perspective view showing a tube container equipped with the sheet welding structure according to this embodiment. FIG. 17 is a schematic cross-sectional view of the tube container of FIG. 16 as viewed in the direction of the arrows along line XVII-XVII. FIG. 18 is a schematic exploded perspective view of a tube container. FIG. 19 is a schematic cross-sectional view showing a sheet immediately before an end seal portion is formed by ultrasonic welding. FIG. 20 is a flow chart showing a method for manufacturing a tube container according to the present embodiment. FIG. 21 is a perspective view of a pack container having a sheet welding structure according to the present embodiment. FIG. 22 is a perspective view showing a pack container having a sheet welding structure according to the present embodiment in a partially unfolded state.

[0011] The following describes a sheet welding structure and a manufacturing method thereof according to one embodiment of the present invention. Also described are a container such as a tube container equipped with the sheet welding structure according to one embodiment of the present invention, and a manufacturing method thereof. In the following description of the embodiment, the same or corresponding parts in the drawings are designated by the same reference numerals, and their description will not be repeated.

[0012] <Sheet Welding Structure> Fig. 1 is a schematic cross-sectional perspective view showing a sheet portion and the like for forming a sheet welding structure according to one embodiment of the present invention. Fig. 2 is a schematic cross-sectional perspective view showing a sheet welding structure according to one embodiment of the present invention.

[0013] 1 and 2, the sheet welding structure 1 is formed by overlapping a first sheet portion SP1 and a second sheet portion SP2 with each other in the thickness direction DT and welding the first sheet portion SP1 and the second sheet portion SP2 to each other. The first sheet portion SP1 and the second sheet portion SP2 are overlapped with each other so that the first sheet portion SP1 is located on one side DT1 in the thickness direction DT and the second sheet portion SP2 is located on the other side DT2 in the thickness direction DT.

[0014] First, a description will be given of the first sheet portion SP1 and the second sheet portion SP2, which are materials of the sheet welding structure 1. Both the first sheet portion SP1 and the second sheet portion SP2 contain polyester-based resin.

[0015] First, the first sheet portion SP1 will be described. Fig. 3 is a schematic cross-sectional view showing the first sheet portion and the second sheet portion. As shown in Figs. 1 and 3, the first sheet portion SP1 according to this embodiment includes a first base layer SL1, one or more first reinforcing layers RL1, and a second base layer SL2.

[0016] In this embodiment, the first base layer SL1 is the outermost layer on the other side DT2 of the first sheet portion SP1. The first base layer SL1 contains a polyester-based resin as a main component. From the viewpoint of improving recyclability, it is preferable that the first base layer SL1 contains a polyester-based resin as a main component. Note that it is also preferable that the content of the polyester-based resin in the first base layer SL1 is 95% by mass or more, or 99% by mass or more.

[0017] Examples of polyester-based resins include polyethylene terephthalate, polyethylene naphthalate, glycol-modified polyethylene terephthalate (PETG, polyethylene terephthalate in which part of the glycol component is modified with cyclohexanedimethanol (CHDM) or neopentyl glycol, etc.), polylactic acid, etc. The first base layer SL1 preferably contains only polyester-based resins as resin components.

[0018] From the viewpoint of the recyclability of the sheet welding structure 1 and containers including the same, the polyester-based resin in the first base layer SL1 is preferably homopolyethylene terephthalate, polyethylene terephthalate such as copolymerized polyethylene terephthalate obtained by copolymerizing ethylene glycol, terephthalic acid, and a third component, or glycol-modified polyethylene terephthalate, with homopolyethylene terephthalate being more preferred. Furthermore, from the viewpoint of welding the first sheet portion SP1 and the second sheet portion SP2 together with relatively low energy and efficiently transmitting ultrasonic vibrations, the polyester-based resin in the first base layer SL1 is preferably an amorphous polyester-based resin (such as amorphous polyethylene terephthalate or glycol-modified polyethylene terephthalate). Therefore, from the viewpoints of both the recyclability of the sheet welding structure 1 and containers including the same and the weldability between the first sheet portion SP1 and the second sheet portion SP2, the first base layer SL1 is most preferably amorphous homopolyethylene terephthalate. From the viewpoint of reducing the environmental load, it is preferable that the polyester-based resin in the first base layer SL1 is made from recycled materials or biomass materials. However, when contents are to be stored in a container having the sheet welding structure 1, it is also preferable that the polyester-based resin in the first base layer SL1 is made from virgin materials.

[0019] The first base layer SL1 may be a single-layer film or a part of a laminate film. The film (single-layer film or laminate film) constituting the first base layer SL1 is an unstretched film. This suppresses crystallization of the surface of the first base layer SL1, improving weldability with the second sheet portion SP2 when ultrasonic welding, which will be described later, is performed to form the sheet welding structure 1.

[0020] The one or more first reinforcing layers RL1 are laminated on one side DT1 of the first base layer SL1 in the thickness direction DT. This improves the strength of the sheet welding structure 1 and a container including the same. This in turn can prevent the container from being damaged when dropped. The one or more first reinforcing layers RL1 may be laminated on the first base layer SL1 via another layer.

[0021] In this embodiment, a plurality of first reinforcing layers RL1 are stacked on one side DT1 of the first base layer SL1 in the thickness direction DT. The plurality of first reinforcing layers RL1 may have the same configuration as each other. The plurality of first reinforcing layers RL1 may have different configurations from each other. The plurality of first reinforcing layers RL1 are stacked on each other. The plurality of first reinforcing layers RL1 may be stacked on each other with other layers interposed therebetween.

[0022] The first reinforcing layer RL1 contains a resin component as a main component, such as a polyester-based resin, a polyolefin-based resin, or a polyamide-based resin. From the viewpoint of improving recyclability, the first reinforcing layer RL1 preferably contains a polyester-based resin as a main component, similar to the first base layer SL1. From the viewpoint of improving strength, the first reinforcing layer RL1 also preferably contains a polyamide-based resin as a main component.

[0023] The polyester-based resin of the first reinforcing layer RL1 is preferably homopolyethylene terephthalate, polyethylene terephthalate such as copolymerized polyethylene terephthalate obtained by copolymerizing ethylene glycol, terephthalic acid, and a third component, glycol-modified polyethylene terephthalate, or polybutylene terephthalate (PBT). It is also preferable that the first reinforcing layer RL1 contains only a polyester-based resin or polybutylene terephthalate as a resin component.

[0024] From the viewpoint of recyclability, the polyester-based resin of the first reinforcing layer RL1 is preferably homopolyethylene terephthalate, polyethylene terephthalate such as copolymerized polyethylene terephthalate obtained by copolymerizing ethylene glycol, terephthalic acid, and a third component, or glycol-modified polyethylene terephthalate, and more preferably homopolyethylene terephthalate. From the viewpoint of reducing the environmental load, the polyester-based resin of the first reinforcing layer RL1 is preferably made from recycled materials or biomass materials. From the viewpoint of reducing the manufacturing costs of the sheet welding structure 1 and a container including the same, it is also preferable that the polyester-based resin of the first reinforcing layer RL1 be made from virgin materials.

[0025] From the viewpoint of further improving the strength of the sheet welding structure 1, it is also preferable that the polyester resin of the first reinforcing layer RL1 is polybutylene terephthalate. Polybutylene terephthalate has a lower melting point and glass transition temperature than polyethylene terephthalate. However, polybutylene terephthalate has higher impact strength than polyethylene terephthalate. Therefore, by using polybutylene terephthalate as the polyester resin of the first reinforcing layer RL1, the recyclability of the sheet welding structure 1 and containers equipped therewith can be improved, while further preventing the container from being damaged by the sheet welding structure 1.

[0026] Examples of the polyolefin resin for the first reinforcing layer RL1 include polyethylene, polypropylene, and cyclic olefin polymer. From the viewpoint of recyclability, the polyolefin resin for the first reinforcing layer RL1 is preferably polypropylene. The polyolefin resin may also be polyethylene.

[0027] Examples of the polyamide-based resin for the first reinforcing layer RL1 include aliphatic polyamides such as polyamide 6 (nylon 6), polyamide 66 (nylon 66), polyamide 610 (nylon 610), polyamide 10 (nylon 10), polyamide 12 (nylon 12), and polyamide 6-12 (nylon 6-12), copolymers thereof, and semi-aromatic polyamides synthesized from aromatic dicarboxylic acids and aliphatic diamines. The polyamide-based resin is preferably polyamide 6 (nylon 6) or polyamide 66 (nylon 66), which are relatively easy to handle.

[0028] Films containing polyamide resins such as nylon 6 and nylon 66 have higher drop strength than polyester resins such as polyethylene terephthalate, so if the first reinforcing layer RL1 contains a polyamide resin, breakage of the sheet welding structure 1 from the container when the container is dropped can be further prevented.

[0029] The film constituting the first reinforcing layer RL1 is a biaxially stretched film. This allows the thickness of the first sheet portion SP1 to be thin while maintaining its strength. Furthermore, when the first sheet portion SP1 includes a first barrier layer BL1 described below, the film constituting the first reinforcing layer RL1 is a biaxially stretched film, which can suppress cracking of the first barrier layer BL1. The first reinforcing layer RL1 may be a single-layer film or may be part of a laminate film. When the first reinforcing layer RL1 is part of a laminate film, the first reinforcing layer RL1 may be configured as one layer of the laminate film together with the first base layer SL1. In this case, the first reinforcing layer RL1 may be laminated directly to the first base layer SL1 without an adhesive layer or the like.

[0030] The first reinforcing layer RL1 is preferably made of a biaxially oriented film containing, for example, a polyester resin as a main component. This allows the sheet welding structure 1 and a container equipped therewith to be made thinner while maintaining their strength. Furthermore, the recyclability of the container equipped with the sheet welding structure 1 is improved.

[0031] The first reinforcing layer RL1 may be a biaxially oriented film containing polyethylene terephthalate, which further improves the recyclability of a container having the sheet welding structure 1. The first reinforcing layer RL1 may be a biaxially oriented film containing polybutylene terephthalate, which improves the strength of the sheet welding structure 1 and a container having the same and suppresses pinhole formation, compared to when the first reinforcing layer RL1 is a biaxially oriented film containing polyethylene terephthalate.

[0032] When multiple first reinforcing layers RL1 are laminated on one side DT1 of the first base layer SL1 in the thickness direction DT, at least one of the multiple first reinforcing layers RL1 may be a biaxially stretched film. However, it is preferable that all of the first reinforcing layers RL1 are biaxially stretched films. All of the multiple first reinforcing layers RL1 contain the resin components that can be contained in the first reinforcing layers RL1 described above. The resin components contained in the multiple first reinforcing layers RL1 may be the same or different among the multiple first reinforcing layers RL1. It is preferable that the first sheet portion SP1 includes two first reinforcing layers RL1, and it is preferable that the first reinforcing layer RL1 on the second base layer SL2 side is a biaxially stretched film containing polyethylene terephthalate as a main component, and the first reinforcing layer RL1 on the first base layer SL1 side is a biaxially stretched film containing polybutylene terephthalate as a main component. In addition, the first sheet portion SP1 may include three first reinforcing layers RL1, and in particular, it is preferable that the first reinforcing layer RL1 on the second base layer SL2 side and the first reinforcing layer RL1 on the first base layer SL1 side are biaxially oriented films containing polyethylene terephthalate as a main component, and the first reinforcing layer RL1 between them is a biaxially oriented film containing polybutylene terephthalate as a main component.

[0033] In this embodiment, the second base layer SL2 is the outermost layer of one side DT1 of the second sheet portion SP2. The second base layer SL2 is laminated on the opposite side of the one or more first reinforcing layers RL1 from the first base layer SL1. That is, the second base layer SL2 is disposed on one side DT1 of the one or more first reinforcing layers RL1 in the thickness direction DT.

[0034] In this embodiment, the second base layer SL2 contains a resin component as a main component, and may contain, for example, a polyolefin-based resin or a polyester-based resin as a main component. The second base layer SL2 may contain a polyester-based resin as a resin component, similar to the first base layer SL1, or may contain a polyester-based resin, polyolefin-based resin, or polyamide-based resin that can be used as a resin component of the first reinforcing layer RL1. The second base layer SL2 preferably contains, as a main component, the same type of resin component as the main component of the first base layer SL1. From the viewpoint of recyclability, the second base layer SL2 preferably also contains, as a main component, a polyester-based resin, similar to the first base layer SL1.

[0035] The polyester-based resin that can be used as the main component of the second base layer SL2 is preferably polyethylene terephthalate or glycol-modified polyethylene terephthalate, and more preferably homopolyethylene terephthalate. From the viewpoint of reducing the environmental impact, the polyester-based resin in the second base layer SL2 is preferably made from recycled materials or biomass materials. From the viewpoint of reducing the manufacturing costs of the sheet welding structure 1 and a container including the same, it is also preferable that the polyester-based resin in the second base layer SL2 be made from virgin materials.

[0036] The second base layer SL2 may be a single layer film or a part of a laminate film. The film (single layer film or laminate film) constituting the second base layer SL2 may be composed of any of a non-stretched film, a uniaxially stretched film, and a biaxially stretched film. The second base layer SL2 is preferably composed of a non-stretched film or a uniaxially stretched film, and more preferably composed of a non-stretched film. It is particularly preferable that the second base layer SL2 contains a polyester resin as a main component and is composed of a non-stretched film.

[0037] In this embodiment, the first sheet portion SP1 further includes a first barrier layer BL1. The first barrier layer BL1 is located on the other side DT2 of one or more first reinforcing layers RL1 in the thickness direction DT, but may also be located on the one side DT1 of one or more first reinforcing layers RL1. The first barrier layer BL1 may also be located between multiple first reinforcing layers RL1. Note that the first sheet portion SP1 does not necessarily include the first barrier layer BL1.

[0038] The material constituting the first barrier layer BL1 is not particularly limited. Examples of the first barrier layer BL1 include a ceramic barrier layer such as a silica barrier layer or an alumina barrier layer, and a metal barrier layer such as an aluminum barrier layer. The ceramic barrier layer may be a transparent vapor deposition layer. In this embodiment, the first barrier layer BL1 is laminated by vapor deposition on one of the films constituting the one or more first reinforcing layers RL1.

[0039] The first sheet portion SP1 may include a plurality of first barrier layers BL1. In this case, the first sheet portion SP1 may include a plurality of first barrier layers BL1 laminated on a plurality of first reinforcing layers RL1 by vapor deposition. The first sheet portion SP1 may simultaneously include one or more first reinforcing layers RL1 on which one or more first barrier layers BL1 are vapor-deposited and one or more first reinforcing layers RL1 on which one or more first barrier layers BL1 are not vapor-deposited. For example, the first sheet portion SP1 may include both a ceramic barrier layer and a metal barrier layer as the plurality of first barrier layers BL1, or may include two ceramic barrier layers.

[0040] In this embodiment, the first sheet portion SP1 further includes a plurality of adhesive layers AL. The plurality of adhesive layers AL are respectively positioned between the first base layer SL1 and the first barrier layer BL1, between the second base layer SL2 and the first reinforcing layer RL1, and between adjacent first reinforcing layers RL1. The adhesive constituting the adhesive layers AL is not particularly limited, but it is preferable to use a dry lamination adhesive. Conventionally known dry lamination adhesives can be used as the dry lamination adhesive.

[0041] The first sheet portion SP1 may further include a printed layer for improving design. The printed layer may be located, for example, on one side DT1 of the first base layer SL1 in the thickness direction DT. It is also preferable that the first sheet portion SP1 does not include a printed layer. The printed layer is made of, for example, ink. Examples of ink include oil-based ink (including solvent-based ink using an organic solvent as a solvent), water-based ink (including water-dispersed emulsion ink), and UV-curable ink.

[0042] The first sheet portion SP1 may further include an anchor coat layer. The anchor coat layer is located between the printed layer and another layer. The anchor coat layer enhances adhesion between the printed layer and another layer. The anchor coat layer can be formed using a conventionally known anchor coating agent or the like.

[0043] When the first sheet portion SP1 includes a printed layer, a transparent protective layer may be further laminated on the printed layer. The transparent protective layer may be a resin film such as a polypropylene film, or a layer made of transparent ink. The first sheet portion SP1 may further include a heat insulating layer. The heat insulating layer is preferably made of a foam material made of a resin component such as polyethylene terephthalate.

[0044] The first sheet portion SP1 as a whole preferably has a content of polyester resin such as polyethylene terephthalate of 85% by mass or more, and more preferably 90% by mass or more.

[0045] From the viewpoint of manufacturing the sheet welding structure 1 according to this embodiment by the manufacturing method described later, the thickness (a １ The thickness (a) of the first sheet portion SP1 is preferably, for example, 12 μm or more and 250 μm or less. １ ) is more preferably 100 μm or more, and even more preferably 120 μm or more.

[0046] The thickness of the first base layer SL1 is preferably thicker than that of the first reinforcing layer RL1. The thickness of the first base layer SL1 is preferably at least 1.5 times, more preferably at least 3 times, and even more preferably at least 5 times that of the first reinforcing layer RL1. The thickness of the first base layer SL1 is preferably at least 10 μm, more preferably at least 60 μm, and is preferably at most 250 μm, more preferably at most 200 μm, and even more preferably at most 80 μm. The thickness of the first base layer SL1 may be, for example, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm.

[0047] The thickness of the first reinforcing layer RL1 is, for example, 5 μm or more and preferably 200 μm or less, and more preferably 100 μm or less. From the viewpoint of reducing the total thickness of the first sheet portion SP1, the thickness of the first reinforcing layer RL1 may be, for example, 5 μm or more and 25 μm or less. When the first barrier layer BL1 is vapor-deposited on the first reinforcing layer RL1, the total thickness of the first reinforcing layer RL1 and the first barrier layer BL1 may be 5 μm or more and 25 μm or less. The total thickness of the first reinforcing layer RL1 and the first barrier layer BL1 may be, for example, 12 μm or 25 μm.

[0048] The thickness of the second substrate layer SL2 is preferably 10 μm or more, more preferably 60 μm or more, and preferably 250 μm or less, more preferably 200 μm or less, and even more preferably 80 μm or less. The thickness of the second substrate layer SL2 may be, for example, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm. The thickness of the second substrate layer SL2 may be the same as that of the first substrate layer SL1. This makes it possible to form the second substrate layer SL2 using the same film as that forming the first substrate layer SL1. The thickness of the second substrate layer SL2 may be different from that of the first substrate layer SL1. It is also preferable that the thickness of the second substrate layer SL2 is thicker than that of the first substrate layer SL1. The second substrate layer SL2 may be the thickest layer in the first sheet portion SP1. The second substrate layer SL2 may be thicker than the first reinforcing layer RL1.

[0049] Next, the second sheet portion SP2 will be described. As shown in Figures 1 and 3, the second sheet portion SP2 according to this embodiment includes a third base material layer SL3, one or more second reinforcing layers RL2, and a fourth base material layer SL4. The second sheet portion SP2 according to this embodiment also includes a second barrier layer BL2 and multiple adhesive layers AL.

[0050] The second sheet portion SP2 can have the same configuration as the first sheet portion SP1. In this embodiment, the third base material layer SL3, one or more second reinforcing layers RL2, the fourth base material layer SL4, the second barrier layer BL2, and the multiple adhesive layers AL of the second sheet portion SP2 can have the same configuration as the first base material layer SL1, one or more first reinforcing layers RL1, the second base material layer SL2, the first barrier layer BL1, and the multiple adhesive layers AL of the first sheet portion SP1, respectively. In this embodiment, the first sheet portion SP1 and the second sheet portion SP2 have the same configuration.

[0051] The fourth base layer SL4 is welded to the first base layer SL1 of the first sheet portion SP1. For this reason, the fourth base layer SL4 is preferably composed of a non-stretched film or a uniaxially stretched film, and more preferably a non-stretched film. If the fourth base layer SL4 is composed of a non-stretched film, crystallization of the surface of the fourth base layer SL4 is suppressed, thereby improving the weldability of the first sheet portion SP1 to the first base layer SL1 when ultrasonic welding is performed.

[0052] The fourth base layer SL4 preferably contains, as a main component, the same resin component as that contained in the first base layer SL1. Similarly to the first base layer SL1, the fourth base layer SL4 also preferably contains, as a main component, a polyester-based resin.

[0053] The second sheet portion SP2 as a whole preferably has a content of polyester-based resin such as polyethylene terephthalate of 85% by mass or more, and more preferably 90% by mass or more.

[0054] From the viewpoint of manufacturing the sheet welding structure 1 according to this embodiment by the manufacturing method described later, the thickness (a ２ The thickness (a) of the second sheet portion SP2 is preferably, for example, 12 μm or more and 250 μm or less. ２ ) is more preferably 100 μm or more, and even more preferably 120 μm or more.

[0055] Next, a method for manufacturing the sheet welding structure will be described with reference to Fig. 4.

[0056] As shown in Figures 1 to 4, a manufacturing method of a sheet welding structure according to one embodiment of the present invention includes overlapping a first sheet portion SP1 and a second sheet portion SP2 in the thickness direction DT (step S1), and welding the first sheet portion SP1 and the second sheet portion SP2 to each other (step S2).

[0057] FIG. 5 is a schematic cross-sectional view showing the first and second sheet portions when pressure is started to be applied to the first and second sheet portions.

[0058] As shown in FIG. 5 , prior to step S2, in step S1, a portion of the first sheet portion SP1 and a portion of the second sheet portion SP2 are overlapped with each other in the thickness direction DT. In this embodiment, the first sheet portion SP1 has a first end face SE1 facing in a direction perpendicular to the thickness direction DT. The second sheet portion SP2 has a second end face SE2 facing in a direction perpendicular to the thickness direction DT. A portion of the first sheet portion SP1 and a portion of the second sheet portion SP2 are overlapped with each other so that the first end face SE1 and the second end face SE2 face in opposite directions. In addition, the surface of the other side DT2 of the first sheet portion SP1 and the surface of one side DT1 of the second sheet portion SP2 contact each other. The first base layer SL1 of the first sheet portion SP1 and the fourth base layer SL4 of the second sheet portion SP2 contact each other.

[0059] FIG. 6 is a schematic cross-sectional view showing the first and second sheet portions when the pressure on the first and second sheet portions has stopped.

[0060] 1, 5, and 6, in step S2, the overlapping first sheet portion SP1 and second sheet portion SP2 are pressed between the first member M1 and the second member M2 so as to sandwich the overlapping first sheet portion SP1 and second sheet portion SP2. Specifically, the first member M1 presses the first sheet portion SP1 from one side DT1 in the thickness direction DT. The second member M2 presses the second sheet portion SP2 from the other side DT2 in the thickness direction DT.

[0061] The first member M1 is one of an anvil and an ultrasonic horn. In this embodiment, the first member M1 is an ultrasonic horn.

[0062] 7 is a partial plan view of the first member M1 as seen from the first pressing surface side. As shown in FIGS. 1 and 5 to 7, the first member M1 has a first pressing surface M11 that presses the first sheet portion SP1.

[0063] The first pressing surface M11 includes one or more first surfaces M11a, one or more second surfaces M11b, and one or more third surfaces M11c.

[0064] The one or more first surfaces M11a are arranged in a pattern when viewed from the first sheet portion SP1 when pressing by the first member M1 begins (hereinafter, this may be referred to as "viewed from the first sheet portion SP1 when pressing begins"; see Figures 5 and 7). The pattern in which the one or more first surfaces M11a are arranged may be a design visible to the naked eye. The pattern in which the one or more first surfaces M11a are arranged may be, for example, stripes, twill (grid), dots, stripes, staggered, or zigzag. The one or more first surfaces M11a may be arranged in a continuous pattern or a discontinuous (random) pattern when viewed from the first sheet portion SP1 when pressing begins.

[0065] In this embodiment, a plurality of first surfaces M11a are arranged on the first member M1. The plurality of first surfaces M11a are arranged in a dotted pattern. Each of the plurality of first surfaces M11a has a substantially rectangular outer shape. The plurality of first surfaces M11a are arranged in a continuous pattern. When viewed from the first sheet portion SP1 at the start of pressing, the plurality of first surfaces M11a are arranged at equal intervals in one direction and in a direction perpendicular to the one direction.

[0066] The one or more first surfaces M11a include a surface that is closest to the first sheet portion SP1 when viewed from the first sheet portion SP1 at the start of pressing. In this embodiment, each of the multiple first surfaces M11a includes a surface that is closest to the first sheet portion SP1 when viewed from the first sheet portion SP1 at the start of pressing.

[0067] The one or more first surfaces M11a may be flat. In this embodiment, each of the plurality of first surfaces M11a is flat. The entirety of the plurality of first surfaces M11a is the surface closest to the first sheet portion SP1.

[0068] The one or more second surfaces M11b are arranged in a pattern so as not to overlap with the first surface M11a when viewed from the first sheet portion SP1 at the start of pressing. The one or more second surfaces M11b can also be arranged in a pattern in which the one or more first surfaces M11a can be arranged.

[0069] In this embodiment, the first member M1 has one second surface M11b arranged in a chevron pattern so as to surround each of the first surfaces M11a when viewed from the first sheet portion SP1 at the start of pressing.

[0070] The one or more second surfaces M11b are located farther from the first sheet portion SP1 than the first surface M11a when the pressing starts. The one or more second surfaces M11b include a surface that is farthest from the first sheet portion SP1 when the pressing starts. Any one of the multiple second surfaces M11b may include this farthest surface, or each of the multiple second surfaces M11b may include this farthest surface.

[0071] One or more of the second surfaces M11b may be flat. In this embodiment, one second surface M11b is flat. Therefore, the entire second surface M11b is the surface farthest from the first sheet portion SP1.

[0072] The one or more third surfaces M11c are disposed between the one or more first surfaces M11a and the one or more second surfaces M11b. The third surfaces M11c connect the first surfaces M11a and the second surfaces M11b. In this embodiment, the multiple third surfaces M11c are disposed so as to surround each of the multiple first surfaces M11a.

[0073] The third surface M11c is inclined with respect to the thickness direction DT at the start of pressing by the first member M1. Of the third surface M11c, a first edge M12 connecting to the first surface M11a is rounded when viewed from the direction in which the first edge M12 extends. Of the third surface M11c, a second edge M13 connecting to the second surface M11b is rounded when viewed from the direction in which the second edge M13 extends. The rounded first edge M12 and / or second edge M13 can prevent the first sheet portion SP1 and the second sheet portion SP2 from being cut by the pressure of the first member M1.

[0074] As described above, the one or more first surfaces M11a and the one or more second surfaces M11b of the first pressing surface M11 can be arranged in various patterns. Fig. 8 is a plan view showing a first pressing surface according to a modified example. Fig. 8 illustrates a first pressing surface M11x according to a modified example in the same plan view as the first pressing surface M11 in Fig. 7.

[0075] As shown in Fig. 8, in the first pressing surface M11x according to the modified example, the plurality of second surfaces M11bx may be arranged in a dotted pattern. Each of the plurality of second surfaces M11bx may have a substantially rectangular outer shape. The plurality of second surfaces M11bx may be arranged in a continuous pattern. When viewed from the first sheet portion SP1 at the start of pressing, the plurality of second surfaces M11bx may be arranged at equal intervals in one direction and in a direction perpendicular to the one direction.

[0076] In the modified example, one first surface M11ax may be arranged in a twill pattern, and the first surface M11ax may be arranged so as to surround each of the plurality of second surfaces M11bx when viewed from the first sheet portion SP1 at the start of pressing.

[0077] Fig. 9 is a plan view showing a first pressing surface according to another modified example. Fig. 10 is a cross-sectional view of the first member in Fig. 9 as seen in the direction of the arrows X-X. Fig. 9 shows a first pressing surface M11y according to another modified example in the same plan view as the first pressing surface M11 in Fig. 7.

[0078] As shown in FIGS. 9 and 10, in a first pressing surface M11y according to another modified example, the third surface M11cy may extend perpendicular to the thickness direction DT when viewed from the first sheet portion SP1 at the start of pressing.

[0079] Next, the second member M2 will be described. The second member M2 is the other of the anvil and the ultrasonic horn. In this embodiment, the second member M2 is an anvil. The second member M2 has a second pressing surface M21 that presses the second sheet portion SP2. In this embodiment, the second pressing surface M21 is flat. The second pressing surface M21 extends in a planar direction perpendicular to the thickness direction DT when viewed from the second sheet portion SP2 where pressing by the second pressing surface M21 begins.

[0080] 5 and 6 , the first pressing surface M11 of the first member M1 presses the first sheet portion SP1, and the second pressing surface M21 of the second member M2 presses the second sheet portion SP2, causing a portion of each of the first sheet portion SP1 and the second sheet portion SP2 to melt and mix together. In this embodiment, the above pressing may be performed by displacing the first member M1 toward the other side DT2 in the thickness direction DT without displacing the second member M2. Alternatively, the above pressing may be performed by displacing the second member M2 toward the one side DT1 in the thickness direction DT without displacing the first member M1.

[0081] In Figure 6, the flow of resin in each layer is schematically indicated by open arrows. The opposing first base layer SL1 of the first sheet portion SP1 and the fourth base layer SL4 of the second sheet portion SP2 (see Figure 5) melt and mix with each other due to the vibrations from the ultrasonic horn. This forms an integrated layer ML between the first reinforcement layer RL1 and the second reinforcement layer RL2 (see Figure 6). The integrated layer ML leaks further from the first end face SE1 and the second end face SE2 in a planar direction intersecting the thickness direction DT due to pressure from the first member M1 and the second member M2.

[0082] The second base layer SL2 of the first sheet portion SP1 is pressed by the first surface M11a of the first pressing surface M11. As a result, immediately after pressing begins, strong local pressure is applied to the second base layer SL2, causing it to quickly melt locally due to vibrations from the ultrasonic horn. The resin (polyester-based resin in this embodiment) of the second base layer SL2 locally melted by the first surface M11a flows into the recessed space formed by the second surface M11b and the third surface M11c. This suppresses local melting by the first surface M11a, and pressing by the second surface M11b begins. That is, the molten second base layer SL2 is further pressed uniformly in a planar direction perpendicular to the thickness direction DT by the first pressing surface M11 (the first surface M11a, the second surface M11b, and the third surface M11c) and the second pressing surface M21.

[0083] In this embodiment, the second surface M11b is arranged in a single twill pattern. This allows the polyester resin of the second base layer SL2, which is first pressed by the first surface M11a and melted, to flow into the twill-patterned recesses formed by the second surface M11b. The twill-patterned recesses increase the number of flow paths for the polyester resin. This allows for a quick transition from localized pressing to overall pressing.

[0084] The molten second base layer SL2 then leaks from the first end surface SE1 in a planar direction intersecting the thickness direction DT. The integrated layer ML and the second base layer SL2 leaking from the first end surface SE1 further intermix. In other words, the first end surface SE1 is embedded in the fourth base layer SL4 by the resin of the fourth base layer SL4 that has flowed in, and is not exposed. As a result, a first mixture portion MX1 formed by the intermixing of the first base layer SL1, second base layer SL2, and fourth base layer SL4 is located on the first end surface SE1 of the first reinforcing layer RL1.

[0085] The third base material layer SL3 of the second sheet portion SP2 is pressed by the second member M2 and melts entirely due to vibrations from the ultrasonic horn. As a result, the third base material layer SL3 leaks from the second end surface SE2 in a planar direction intersecting the thickness direction DT. The integrated layer ML and the third base material layer SL3 leaking from the second end surface SE2 further intermix. In other words, the second end surface SE2 is embedded in the first base material layer SL1 by the resin of the first base material layer SL1 that has flowed in, and is not exposed. As a result, a second mixture portion MX2 formed by the intermixing of the first base material layer SL1, second base material layer SL2, and third base material layer SL3 is located on the second end surface SE2 of the second reinforcing layer RL2.

[0086] Here, as shown in Fig. 5, when the first member M1 starts to press the first sheet portion SP1, the distance in the thickness direction DT between the surface of the first surface M11a closest to the first sheet portion SP1 and the surface of the second surface M11b farthest from the first sheet portion SP1 is defined as b. Then, as shown in Fig. 6, when the first member M1 and the second member M2 are closest to each other during welding of the first sheet portion SP1 and the second sheet portion SP2, the distance in the thickness direction DT between the second surface M11b and the second pressing surface M21 is defined as c'. In this case, the manufacturing method of the sheet welding structure according to this embodiment satisfies the following relational expressions (1) and (2).

[0087] According to the above-mentioned relational expression (1), the first surface M11a can locally press relatively deeply in the thickness direction DT before the entire first pressing surface M11 presses. Therefore, the first sheet portion SP1 and the second sheet portion SP2 can be sandwiched with a relatively high pressing force in the initial pressing stage. Furthermore, in the final pressing stage, both the first surface M11a and the second surface M11b of the first pressing surface M11 reliably press the first sheet portion SP1 and the second sheet portion SP2 so that the above-mentioned relational expression (2) is satisfied. Therefore, the first sheet portion SP1 and the second sheet portion SP2 can be sandwiched with a relatively high pressing force even when the polyester-based resin has progressed to melting. This allows for the provision of a sheet welding structure 1 formed by firmly welding the first sheet portion SP1 and the second sheet portion SP2, each containing a polyester-based resin, to each other.

[0088] The manufacturing method of the sheet welding structure further satisfies the following relations (3) and (4). １ is the thickness of the first sheet portion SP1, and a ２ is the thickness of the second sheet portion SP2.

[0089] By adjusting the distance b so that the above relational expression (4) is satisfied, the first surface M11a can be prevented from breaking through the first sheet portion SP1 and the second sheet portion SP2, thereby preventing partial fracture of the sheet welding structure 1.

[0090] In addition, compared to other resins or biaxially stretched films of polyester-based resin (polyethylene terephthalate), unstretched or uniaxially stretched films of polyester-based resin (polyethylene terephthalate), the viscosity of the unstretched or uniaxially stretched film of polyester-based resin (polyethylene terephthalate) decreases quickly when heated, and the film hardens quickly when cooled. Therefore, when the second base layer SL2 is an unstretched or uniaxially stretched film of polyester-based resin (polyethylene terephthalate), the polyester-based resin of the second base layer SL2 that flows into the recesses described above solidifies easily. A gap may form between the solidified polyester-based resin of the second base layer SL2 and the second surface M11b. If a gap forms, the pressing force applied by the second surface M11b may be insufficient, resulting in insufficient uniform pressing force applied by the first pressing surface M11.

[0091] Therefore, the length of b is a １ The above and (3a １ It is also preferable that the length of b is smaller than that of a １ The length of b may be less than 1.5 times, 1.4 times or less, 1.3 times or less, 1.2 times or less, or 1.1 times or less. １ Greater than and a １ The shorter the length of b, the more likely it is that a gap will be prevented from occurring between the second surface M11b and the molten polyester resin of the second base layer SL2.

[0092] As described above, in the manufacturing method of the sheet welding structure 1 according to this embodiment, both the second surface M11b and the second pressing surface M21 are flat. This allows the first sheet portion SP1 and the second sheet portion SP2 to be sandwiched relatively uniformly even at the end of the pressing process, when the polyester resin has melted. This in turn prevents partial breakage of the sheet welding structure 1.

[0093] Next, the sheet welding structure 1 manufactured by the above manufacturing method will be described in more detail. Fig. 11 is a schematic cross-sectional view showing the sheet welding structure. Fig. 12 is a plan view of the sheet welding structure seen from one side. Fig. 11 shows the same cross-sectional view as the first sheet portion SP1 and second sheet portion SP2 shown in Fig. 5 and the sheet welding structure being melted shown in Fig. 6.

[0094] As shown in Figures 2, 11 and 12, the sheet welding structure 1 comprises one or more thin-walled portions 10, one or more thick-walled portions 20, one or more connecting portions 30, a first extending sheet portion 40 and a second extending sheet portion 50.

[0095] The one or more thin-walled portions 10 are arranged in a pattern when the sheet welding structure 1 is viewed from one side DT1 in the thickness direction DT. The pattern in which the one or more thin-walled portions 10 are arranged may be a design visible to the naked eye. The pattern in which the one or more thin-walled portions 10 are arranged may be, for example, striped, twill (grid), dotted, striped, staggered, or zigzag. The one or more thin-walled portions 10 may be arranged in a continuous pattern or a discontinuous (random) pattern when viewed from one side DT1 in the thickness direction DT.

[0096] In this embodiment, the one or more thin-walled portions 10 are a plurality of thin-walled portions 10. The plurality of thin-walled portions 10 are arranged in a dotted pattern. Each of the plurality of thin-walled portions 10 is arranged in a continuous pattern when viewed from one side DT1 in the thickness direction DT. When viewed from one side DT1 in the thickness direction DT, the plurality of thin-walled portions 10 are arranged at equal intervals in one direction and in a direction perpendicular to the one direction.

[0097] The one or more thin-walled portions 10 include a portion 11 having the thinnest thickness in the thickness direction DT in the sheet welding structure 1. In this embodiment, each of the plurality of thin-walled portions 10 includes the portion 11.

[0098] The one or more thin-walled portions 10 have a first structural surface 12 and a second structural surface 13. The first structural surface 12 faces one side DT1 in the thickness direction DT. The first structural surface 12 may be flat. In this embodiment, each of the multiple first structural surfaces 12 is flat. The multiple first structural surfaces 12 are aligned in a direction perpendicular to the thickness direction DT.

[0099] The second structure surface 13 faces the other side DT2 in the thickness direction DT. The second structure surface 13 may be flat. In this embodiment, each of the multiple second structure surfaces 13 is flat. The multiple second structure surfaces 13 are aligned in a direction perpendicular to the thickness direction DT. In this embodiment, the entire multiple thin-walled portions 10 form the thinnest part 11 in the sheet welding structure 1 in the thickness direction DT.

[0100] The one or more thick portions 20 are arranged so as not to overlap with the thin portions 10 when the sheet welding structure 1 is viewed from one side DT1 in the thickness direction DT. The one or more thick portions 20 are arranged in a pattern when viewed from one side DT1 in the thickness direction DT. The one or more thick portions 20 can also be arranged in a pattern in which the one or more thin portions 10 can be arranged.

[0101] The sheet welding structure 1 according to this embodiment has one thick portion 20. The thick portion 20 is arranged in a twill pattern. When viewed from one side DT1 in the thickness direction DT, the thick portion 20 is arranged so as to surround each of the plurality of thin portions 10.

[0102] The one or more thick portions 20 have a thickness in the thickness direction DT greater than that of the thin portion 10. Each of the multiple thick portions 20 may have a thickness in the thickness direction DT greater than that of the thin portion 10. The one or more thick portions 20 include a portion 21 that is thickest in the thickness direction DT in the sheet welding structure 1. Any one of the multiple thick portions 20 may include this portion 21, or each of the multiple thick portions 20 may include this portion 21.

[0103] The one or more thick portions 20 have a third structural surface 22 and a fourth structural surface 23. The third structural surface 22 faces one side DT1 in the thickness direction DT. In this embodiment, the third structural surface 22 is flat. Each of the multiple third structural surfaces 22 may be flat. The multiple third structural surfaces 22 may be aligned in a direction perpendicular to the thickness direction DT.

[0104] The fourth structural surface 23 faces the other side DT2 in the thickness direction DT. In this embodiment, the fourth structural surface 23 is flat. In this embodiment, the entire thick portion 20 is the thickest part 21 in the thickness direction DT in the sheet welding structure 1. Note that each of the multiple fourth structural surfaces 23 may be flat. Each of the multiple fourth structural surfaces 23 may be aligned in a direction perpendicular to the thickness direction DT.

[0105] In this embodiment, the fourth structural surface 23 of the thick portion 20 and the second structural surface 13 of the thin portion 10 are aligned with each other in a direction perpendicular to the thickness direction DT and are flat.

[0106] One or more connection portions 30 are arranged between one or more thin portions 10 and one or more thick portions 20. The connection portions 30 connect the thin portions 10 and the thick portions 20. In this embodiment, the multiple connection portions 30 are arranged so as to surround each of the multiple thin portions 10.

[0107] The multiple connection portions 30 have a fifth structural surface 31 and a sixth structural surface 34. The fifth structural surface 31 faces one side DT1 in the thickness direction DT. The fifth structural surface 31 connects the first structural surface 12 and the third structural surface 22. The fifth structural surface 31 is inclined with respect to the thickness direction DT. Of the fifth structural surface 31, a first edge 32 connecting with the first structural surface 12 is rounded when viewed from the extending direction of the first edge 32. Of the fifth structural surface 31, a second edge 33 connecting with the third structural surface 22 is rounded when viewed from the extending direction of the second edge 33. The sixth structural surface 34 is aligned with the fourth structural surface 23 of one or more thick portions 20 and with the second structural surface 13 of one or more thin portions 10 in a direction perpendicular to the thickness direction DT, and further, the sixth structural surface 34 is flat.

[0108] As described above, the one or more thin portions 10 and the one or more thick portions 20 can be arranged in various patterns. Fig. 13 is a plan view showing a modified sheet welding structure. In Fig. 13, the modified sheet welding structure 1 is shown in the same plan view as the sheet welding structure 1 in Fig. 12. The modified sheet welding structure 1x is a sheet welding structure 1x manufactured using a first member M1x having a first pressing surface M11x shown in Fig. 8.

[0109] As shown in Fig. 13, in a sheet welding structure 1x according to a modified example, a plurality of thick portions 20x may be arranged in a dotted pattern. Each of the plurality of thick portions 20x may have a substantially rectangular outer shape. The plurality of thick portions 20x may be arranged in a continuous pattern. The plurality of thick portions 20x may be arranged at equal intervals in one direction and in a direction perpendicular to the one direction.

[0110] The thin portions 10x in this modified example may be arranged in a twill pattern. The thin portions 10x may be arranged so as to surround each of the plurality of thick portions 20x.

[0111] Fig. 14 is a plan view showing a sheet welding structure according to another modification. Fig. 15 is a cross-sectional view of the sheet welding structure of Fig. 14 as seen in the direction of the arrows XV-XV. Fig. 14 shows a sheet welding structure 1y according to another modification in the same plan view as the sheet welding structure 1 in Fig. 12.

[0112] As shown in FIGS. 14 and 15, in a sheet welding structure 1y according to another modification, a thin portion 10y and a thick portion 20y may be directly connected to each other.

[0113] The sheet welding structure 1 according to this embodiment will be described in further detail. As shown in Figures 5, 6, and 11, the thin-walled portions 10, the thick-walled portions 20, and the connecting portions 30 are formed of first sheet portions SP1 and second sheet portions SP2 in the manufacturing method described above. One or more thin-walled portions 10, one or more thick-walled portions 20, and one or more connecting portions 30 may include the second base material layer SL2, one or more first reinforcing layers RL1, the integral layer ML, one or more second reinforcing layers RL2, and the first base material layer SL1 that are melted and solidified in step S2 of the manufacturing method described above.

[0114] The one or more thin portions 10, the one or more thick portions 20, and the one or more connecting portions 30 do not necessarily have to include the first mixed portion MX1 and the second mixed portion MX2. The first mixed portion MX1 and the second mixed portion MX2 are located at the edge portions in the direction perpendicular to the thickness direction DT of the region of the sheet welding structure 1 that is configured by the thin portions 10, the thick portions 20, and the connecting portions 30 (hereinafter, sometimes referred to as the "welded region").

[0115] The first extending sheet portion 40 includes a portion of the first sheet portion SP1 that is not welded to the second sheet portion SP2. The first extending sheet portion 40 includes a portion of the first sheet portion SP1 that is not pressed by the first member M1 in step S2 of the manufacturing method of the sheet welding structure 1 described above.

[0116] The first extending sheet portion 40 extends from the welded region in a direction perpendicular to the thickness direction DT. The second base material layer SL2 of the first sheet portion SP1 is continuous with the melted and solidified second base material layer SL2 in the welded region. The first base material layer SL1 of the first sheet portion SP1 is continuous with the second mixed portion MX2.

[0117] The second extending sheet portion 50 includes a portion of the second sheet portion SP2 that is not welded to the first sheet portion SP1. The second extending sheet portion 50 includes a portion of the second sheet portion SP2 that is not pressed by the second member M2 in step S2 of the manufacturing method of the sheet welding structure 1 described above.

[0118] The second extending sheet portion 50 extends from the welded region in a direction perpendicular to the thickness direction DT. In this embodiment, the second extending sheet portion 50 extends on the opposite side from the first extending sheet portion 40. However, the second extending sheet portion 50 may extend from the welded region along the first extending sheet portion 40. The third base material layer SL3 of the second sheet portion SP2 is continuous with the third base material layer SL3 that has melted and solidified in the welded region. The fourth base material layer SL4 of the second sheet portion SP2 is continuous with the first mixed portion MX1.

[0119] 2 and 11, the thickness of the thickest part 21 in the thick-walled portion 20 is c, and the thickness of the thinnest part 11 in the thin-walled portion 10 is d. In this case, the sheet welding structure 1 according to this embodiment satisfies the following relational expressions (5) and (6).

[0120] As shown in the above relational expression (5), the sheet welding structure 1 has a relatively large thickness between the patterned thin portions 10 and the patterned thick portions 20. Therefore, the polyester resin of the first sheet portion SP1 and the polyester resin of the second sheet portion SP2 flow not only in the thickness direction DT but also in a direction intersecting the thickness direction DT (from the thin portions 10 toward the thick portions 20), resulting in thorough mixing. Furthermore, as shown in the above relational expression (6), the sheet welding structure 1 is sufficiently compressed relative to the first sheet portion SP1 and the second sheet portion SP2 before welding. Therefore, this embodiment can provide a sheet welding structure 1 in which the first sheet portion SP1 and the second sheet portion SP2 are firmly welded to each other.

[0121] The dimensions of (cd) are a１ For example, the length of cd is a １ It may be less than 1.5 times, 1.4 times or less, 1.3 times or less, 1.2 times or less, or 1.1 times or less.

[0122] Furthermore, the sheet welding structure 1 further satisfies the following relations (7) and (8). １ is the thickness of the first sheet portion SP1 before welding, and a ２ is the thickness of the second sheet portion SP2 before welding. １ is the thickness of the first extending sheet portion 40, and a ２ may be the thickness of the second extending sheet portion 50.

[0123] As shown in the above formula (8), the thickness of the thin-walled portion 10 is configured not to be too thin, thereby providing a sheet welding structure 1 in which the formation of pinholes is suppressed.

[0124] Furthermore, in this embodiment, both surfaces of the thick portion 20 (the third structural surface 22 and the fourth structural surface 23) are flat.

[0125] As a result, the thick portion 20 compressed as shown in the above formula (5) is compressed uniformly, thereby providing a sheet welding structure 1 in which the first sheet portion SP1 and the second sheet portion SP2 are more firmly welded to each other.

[0126] <Container> Next, a container that can be provided with the sheet welding structure 1 according to this embodiment and a method for manufacturing the same will be described. First, a tube container that can be provided with the sheet welding structure 1 according to this embodiment will be described.

[0127] <Tube container> Fig. 16 is a perspective view showing a tube container having a sheet welding structure according to this embodiment. As shown in Fig. 16, the tube container 100 has a body portion 110, a spout portion 120, an end seal portion 130, and a cap portion 140. The tube container 100 does not necessarily have to have the cap portion 140.

[0128] Figure 17 is a schematic cross-sectional view of the tube container of Figure 16 as viewed in the direction of the arrows along line XVII-XVII. Figure 18 is a schematic exploded perspective view of the tube container. The body portion 110 is formed by shaping a sheet S including a first sheet portion SP1 and a second sheet portion SP2 into a cylindrical shape. The body portion 110 has the sheet welding structure 1 according to this embodiment as a side seal portion 112.

[0129] This makes it possible to provide a tube container 100 that is molded from a sheet S containing a polyester resin, which improves recyclability and has a more firmly formed side seal portion 112.

[0130] The side seal portion 112 is formed by welding together the side edges of the cylindrically formed sheet S. That is, in this embodiment, the first sheet portion SP1 and the second sheet portion SP2 are one side edge and the other side edge of the sheet S, respectively.

[0131] In this embodiment, one side DT1 of the side seal portion 112 (sheet welding structure 1) in the thickness direction DT is on the exterior side of the trunk portion 110. The other side DT2 of the side seal portion 112 (sheet welding structure 1) in the thickness direction DT is on the storage space side of the trunk portion 110. Note that the one side DT1 of the side seal portion 112 in the thickness direction DT may be on the storage space side of the trunk portion 110. The other side DT2 of the side seal portion 112 in the thickness direction DT may be on the exterior side of the trunk portion 110. The side seal portion 112 (sheet welding structure 1) extends in a strip shape in the trunk portion 110. Furthermore, an uneven surface is formed on the one side DT1 of the side seal portion 112 (sheet welding structure 1) in the thickness direction DT, i.e., the surface on the exterior side of the trunk portion 110.

[0132] Furthermore, in this embodiment, the first base layer SL1 and the third base layer SL3 are continuous in the sheet S. The first base layer SL1 and the third base layer SL3 are composed of a single film. The second base layer SL2 and the fourth base layer SL4 are continuous in the sheet S. The second base layer SL2 and the fourth base layer SL4 are composed of a single film. One or more first reinforcing layers RL1 and one or more second reinforcing layers RL2 are each continuous to one another in the sheet S. The first reinforcing layer RL1 and the corresponding second reinforcing layer RL2 are composed of a single film.

[0133] The trunk 110 further includes a main body 111, which is a portion other than the side seal portion. The main body 111 is connected to the first extending sheet portion 40 and the second extending sheet portion 50 of the side seal portion 112 (sheet welding structure 1).

[0134] A spout portion 120 is joined to one axial end 113 of the cylindrically molded body portion 110. An end seal portion 130 is connected to the other axial end 114 of the cylindrically molded body portion 110.

[0135] The outlet 120 is preferably composed of a resin composition containing a polyester resin as a main component. The polyester resin in the outlet 120 can be the same as the polyester resin in the first base layer SL1 and the third base layer SL3. From the viewpoint of the recyclability of the tube container 100, the polyester resin in the outlet 120 is preferably homopolyethylene terephthalate, polyethylene terephthalate such as copolymerized polyethylene terephthalate obtained by copolymerizing ethylene glycol, terephthalic acid, and a third component, or glycol-modified polyethylene terephthalate, and more preferably homopolyethylene terephthalate. Furthermore, from the viewpoint of the moldability of the outlet 120, the polyester resin in the outlet 120 is preferably an amorphous polyester resin (such as amorphous polyethylene terephthalate or glycol-modified polyethylene terephthalate). The polyester resin in the outlet 120 may also be a crystalline polyester resin (for example, crystalline polyethylene terephthalate). From the viewpoint of recyclability of the tube container 100, the resin composition constituting the pouring portion 120 preferably contains only a polyester-based resin as a resin component. The resin composition constituting the pouring portion 120 may further contain a conventionally known additive. From the viewpoint of reducing the environmental load, the polyester-based resin in the resin composition is preferably made from recycled materials or raw materials derived from biomass, but from the viewpoint of reducing the manufacturing cost of the pouring portion 120, it is also preferable that the polyester-based resin in the resin composition is made from virgin raw materials.

[0136] In this embodiment, the pouring portion 120 is an injection-molded product of a resin composition. The intrinsic viscosity (IV) value of the polyester resin material used to mold the pouring portion 120 may be, for example, 0.60 or more and 0.90 or less when measured in accordance with JIS standard (K7390-1:2015). If the IV value is 0.60 or more and 0.90 or less, the pouring portion 120 can be easily molded.

[0137] The end seal portion 130 closes the other axial end portion 114 of the body portion 110. The end seal portion 130 has a flattened outer shape.

[0138] End seal portion 130 is formed by butting together and welding the inner peripheral surfaces of sheets S formed into a cylindrical shape to form body portion 110. End seal portion 130 may be formed by joining the inner peripheral surfaces of sheets S formed into a cylindrical shape by so-called hot air welding. Note that the configuration of end seal portion 130 is not particularly limited as long as it seals the other end portion 114 of body portion 110.

[0139] The end seal portion 130 may have a configuration that can be possessed by the sheet welding structure 1 according to this embodiment. Fig. 19 is a schematic cross-sectional view showing a sheet immediately before the end seal portion is formed by ultrasonic welding. Fig. 19 shows a cylindrically formed sheet S from a cross-sectional direction similar to the cross-sectional direction of Fig. 17.

[0140] As shown in FIG. 19 , the end seal portion 130 can be formed by further sandwiching the cylindrically formed sheet S between a third member M3 and a fourth member M4. One of the third member M3 and the fourth member M4 is an ultrasonic horn, and the other is an anvil. The third member M3 can have the same configuration as the first member M1. The fourth member M4 can have the same configuration as the second member M2. In this case, it is preferable that the side seal portion 112, which is provided to form the sheet S into a cylindrical shape, be positioned on the side of the fourth member M4, which has a flat pressing surface. This allows the side seal portion 112 to have relatively little effect on the sheet welding structure 1 when forming the end seal portion 130.

[0141] 19, when the sheet welding structure 1 formed as the end seal portion 130 is used as a reference, it can be understood that the third base material layer SL3z is continuous with the second base material layer SL2, and the fourth base material layer SL4z is continuous with the first base material layer SL1 in the sheet S. When the sheet welding structure 1 formed as the end seal portion 130 is used as a reference, it can be understood that the third base material layer SL3z and the second base material layer SL2 are composed of a single film, and the fourth base material layer SL4z and the first base material layer SL1 are composed of a single film.

[0142] The cap portion 140 is made of a resin composition. From the viewpoint of recyclability of the tube container 100, the cap portion 140 is preferably made of a resin composition containing a polyester-based resin as a main component. When the tube container 100 is provided with the cap portion 140, it is preferable that the content of the polyester-based resin, such as polyethylene terephthalate, in the tube container 100 as a whole is 95 mass % or more.

[0143] The polyester-based resin in the cap portion 140 can be the same as the polyester-based resin in the first base layer SL1. From the viewpoint of recyclability of the tube container 100, the polyester-based resin in the cap portion 140 is preferably homopolyethylene terephthalate, polyethylene terephthalate such as copolymerized polyethylene terephthalate obtained by copolymerizing ethylene glycol, terephthalic acid, and a third component, or glycol-modified polyethylene terephthalate, and more preferably homopolyethylene terephthalate. Furthermore, from the viewpoint of formability of the cap portion 140, the polyester-based resin in the cap portion 140 is preferably an amorphous polyester-based resin (such as amorphous polyethylene terephthalate or glycol-modified polyethylene terephthalate).

[0144] The method for manufacturing the tube container 100 will be described in more detail. Fig. 20 is a flow chart showing the method for manufacturing the tube container according to this embodiment. As shown in Fig. 20, the method for manufacturing the tube container according to this embodiment includes preparing a sheet S (step S10), forming a cylindrical body including a body portion 110 (step S20), joining the spout portion 120 to the cylindrical body (step S30), attaching the cap portion 140 to the spout portion 120 (step S40), and forming the end seal portion 130 (step S50).

[0145] In step S10, a sheet S including a first sheet portion SP1 and a second sheet portion SP2 is prepared. Step S20 includes overlapping the first sheet portion SP1 and the second sheet portion SP2 while curling the sheet S (S1), and welding the first sheet portion SP1 and the second sheet portion SP2 to each other (S2). Thus, step S2 includes a method for manufacturing the sheet welding structure 1 according to this embodiment (see FIG. 4).

[0146] In step S30, spout portion 120 is joined to a cylindrical body including body portion 110 formed from sheet S. Spout portion 120 can be joined to the cylindrical body by so-called insert molding. Note that spout portion 120 may be joined to the cylindrical body by compression molding or ultrasonic welding instead of the insert molding.

[0147] In step S40, the pre-molded cap portion 140 is attached to the dispensing portion 120. The cap portion 140 can be molded by a conventionally known method such as injection molding or compression molding. If the tube container 100 does not have the cap portion 140, the manufacturing method for the tube container does not need to include step S5.

[0148] In step S50, as described above, the inner surfaces of the cylindrical bodies are hot air welded or ultrasonically welded (see FIG. 19) to form end seal portion 130.

[0149] The tube container 100 according to this embodiment is manufactured as described above. Note that the manufacturing method for the tube container 100 according to this embodiment includes step S40 and step S50 in this order, but this order may be reversed. Furthermore, when manufacturing a tube container containing a content, which will be described later, for example, after step S30 or step S40 and before step S50, the content may be filled into the cylindrical body from the opening on the side opposite the dispensing portion 120. Furthermore, when manufacturing a tube container containing a content, the content may be filled into the cylindrical body from the dispensing portion 120 after step S50.

[0150] As described above, the manufacturing method of a tube container according to this embodiment includes forming a body portion 110 by molding a sheet S including a first sheet portion SP1 and a second sheet portion SP2 into a cylindrical shape so as to form a side seal portion 112 consisting of a sheet welding structure 1 manufactured by the manufacturing method of a sheet welding structure described above.

[0151] This allows the tube container 100 to be manufactured using a sheet S containing a polyester resin, which improves recyclability and has a more firmly formed side seal portion 112.

[0152] Furthermore, the tube container 100 according to the embodiment described above has excellent recyclability because the sheet S constituting the cylindrical body portion 110 can contain a polyester-based resin as a primary component. Furthermore, the cylindrical body portion 110, the spout portion 120, and the end seal portion 130 as a whole contain a polyester-based resin as a primary component, thereby further improving the recyclability of the tube container 100. Furthermore, the tube container 100 according to the embodiment described above contains a polyester-based resin as a primary component, thereby further improving the recyclability of the tube container 100. Therefore, the tube container 100 according to one embodiment of the present invention is in line with the sustainable circular economy sought by the SDGs (Sustainable Development Goals) and can significantly contribute to reducing plastic waste. In this specification, a component containing a polyester-based resin as a primary component can mean that the polyester-based resin content in the component is 85% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more.

[0153] <Tube container filled with contents> In the body 110 of the tube container 100 according to this embodiment, the resins (first base material layer SL1 and third base material layer SL3) that come into direct contact with the contents are polyester-based resins, which relatively prevents the components adsorbable to polyolefin-based resins from being adsorbed onto the tube container 100 and prevents the tube container 100 from absorbing these components and swelling. In addition, because the side seal 112 is firmly joined, it is possible to prevent the surfactant from leaking out of the side seal 112.

[0154] Examples of oil-soluble compounds include tocopherols such as DL-α-tocopherol, D-δ-tocopherol, DL-α-tocopherol acetate, DL-α-tocopherol succinate, DL-α-tocopherol nicotinate, and DL-α-tocopherol linoleate; 3-methyl-4-isopropylphenol (also known as isopropylmethylphenol); and the like. For example, oil-soluble compounds are contained in the contents when the contents are pharmaceuticals, foods, or cosmetics. The tocopherols are known as vitamin E and its derivatives, and are incorporated into the contents in the hopes of anti-aging effects, peripheral vasodilating effects, and promoting blood circulation. 3-methyl-4-isopropylphenol is incorporated as a disinfectant and preservative into cosmetics such as acne cosmetics and pharmaceuticals.

[0155] Examples of oily components include triacylglycerol; diacylglycerol; natural oils and fats such as rapeseed oil, rapeseed oil, sesame oil, sunflower oil, corn oil, rice oil, grape oil, camellia oil, macadamia nut oil, olive oil, castor oil, safflower oil, soybean oil, tea seed oil, cocoa butter, coconut oil, hardened coconut oil, palm oil, Japan wax, hardened castor oil, beeswax, candelilla wax, carnauba wax, lanolin, liquid lanolin, jojoba wax, hard lanolin, polyoxyethylene lanolin alcohol ether, and polyoxyethylene cholesterol ether; hydrocarbon oils and fats such as liquid paraffin, ozokerite, squalene, paraffin, ceresin, petrolatum, and microcrystalline wax; isopropyl myristate, octyldodecyl myristate, and isopropyl palmitate. Examples of suitable oil-based ingredients include synthetic oil components such as ethanol, cholesteryl 12-hydroxystearate, ethylene glycol di-2-ethylhexyl, dipentaerythritol fatty acid ester, pentaerythritol tetra-2-ethylhexyl, glycerin tri-2-ethylhexyl, trimethylolpropane triisostearate, cetyl-2-ethylhexanoate, and castor oil fatty acid methyl ester; and linear polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane; cyclic polysiloxanes such as decamethylpolysiloxane, dodecamethylpolysiloxane, and tetramethyltetrahydrogenpolysiloxane; silicone resins capable of forming a three-dimensional network structure; and silicones such as silicone rubber. These oil-based ingredients are contained in the contents, for example, when the contents are foods such as mayonnaise or cosmetics.

[0156] Examples of volatile oily components include relatively low molecular weight silicone oils, relatively low molecular weight hydrocarbon oils, ether oils, etc. Silicone oils include linear silicones and cyclic silicones. Specific examples of silicone oils include linear dimethylpolysiloxanes and cyclic dimethylpolysiloxanes. The linear dimethylpolysiloxanes may be either linear or branched, and linear ones include dimethylpolysiloxane (1.5cs), dimethylpolysiloxane (2cs), etc., while branched ones include methyltrimethicone, tris(trimethylsilyl)methylsilane, tetrakis(trimethylsilyl)silane, etc. Cyclic dimethylpolysiloxanes include octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, etc. Examples of hydrocarbons include isododecane, isotridecane, isohexadecane, light isoparaffin, light liquid isoparaffin, etc. Examples of ether oils include ethyl perfluorobutyl ether, etc. These volatile oily components are mainly contained in the contents when the contents are cosmetics such as sunscreen oil-in-water emulsion cosmetics.

[0157] Examples of fragrances include peppermint oil, spearmint oil, anise oil, eucalyptus oil, wintergreen oil, cassia oil, clove oil, thyme oil, sage oil, lemon oil, orange oil, mint oil, cardamom oil, coriander oil, mandarin oil, lime oil, lavender oil, rosemary oil, laurel oil, chamomile oil, caraway oil, marjoram oil, bay oil, lemongrass oil, origanum oil, pine needle oil, neroli oil, rose oil, jasmine oil, grapefruit oil, sweetie oil, yuzu oil, cinnamon bark oil, perilla oil, wintergreen oil, clove oil, and pi Natural fragrances such as menthol oil, tea tree oil, taban oil, star anise oil, fennel oil, diatomaceous oil, basil oil, iris concrete, peppermint absolute, rose absolute, orange flower, and nutmeg, or fragrances obtained by processing these natural fragrances (such as front-end cutting, back-end cutting, fractional distillation, liquid-liquid extraction, essence preparation, and powdered fragrance preparation); camphor, menthol, carvone, benzyl succinate, anethole, cineole, methyl salicylate, cinnamic aldehyde, eugenol, methyleugenol, 3-l-menthoxy Propane-1,2-diol, thymol, linalool, linalyl acetate, limonene, menthone, menthyl acetate, N-substituted-paramenthan-3-carboxamide, pinene, octyl aldehyde, citral, pulegone, carbeth acetate, anisaldehyde, ethyl acetate, ethyl butyrate, allyl cyclohexane propionate, methyl anthranilate, ethyl methylphenylglycidate, vanillin, undecalactone, hexanal, butanol, isoamyl alcohol, hexenol, dimethyl sulf Examples of flavorings include single flavorings such as methyl acrylate, cyclotene, furfural, trimethylpyrazine, ethyl lactate, ethyl thioacetate, ocimene, n-decyl alcohol, methyl acetate, citronellyl acetate, ethyl linalool, vanillin, and benzaldehyde; and compound flavorings such as strawberry flavor, apple flavor, banana flavor, pineapple flavor, grape flavor, mango flavor, butter flavor, milk flavor, fruit mix flavor, and tropical fruit flavor.These flavors are contained in the contents when the contents are oral compositions, for example.Flavors may also be contained in the contents as food aroma components such as wasabi, mustard, and the like.

[0158] Examples of sweeteners include saccharin, saccharin sodium, acesulfame potassium, stevia extract, stevioside, neohesperidyl dihydrochalcone, glycyrrhizin, perillartine, thaumatin, aspartylphenylalanine methyl ester, methoxycinnamic aldehyde, palatinose, palatinit, erythritol, maltitol, xylitol, lactitol, etc. These sweeteners are contained in the contents when the contents are, for example, an oral composition.

[0159] Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Examples of anionic surfactants include fatty acid soaps, higher alkyl sulfates, alkyl ether sulfates, N-acylsarcosinic acid, higher fatty acid amide sulfonates, phosphate salts, sulfosuccinates, alkylbenzene sulfonates, higher fatty acid ester sulfates, N-acylglutamates, sulfated oils, POE-alkyl ether carboxylic acids, POE-alkyl allyl ether carboxylates, α-olefin sulfonates, higher fatty acid ester sulfonates, secondary alcohol sulfates, higher fatty acid alkylolamide sulfates, sodium lauroyl monoethanolamide succinate, N-palmitoyl aspartic acid ditriethanolamine, and sodium caseinate. Examples of cationic surfactants include alkyltrimethylammonium salts, alkylpyridinium salts, distearyldimethylammonium chloride, dialkyldimethylammonium salts, poly(N,N'-dimethyl-3,5-methylenepiperidinium) chloride, alkyl quaternary ammonium salts, alkyldimethylbenzylammonium salts, alkylisoquinolinium salts, dialkylmorphonium salts, POE-alkylamines, alkylamine salts, polyamine fatty acid derivatives, amyl alcohol fatty acid derivatives, benzalkonium chloride, and benzethonium chloride. Examples of amphoteric surfactants include imidazoline-based amphoteric surfactants and betaine-based surfactants. Examples of nonionic surfactants include polyoxyethylene hydrogenated castor oil, polyoxyethylene alkyl ethers, sucrose fatty acid esters, alkyl glycosides, polyoxyethylene-polyoxypropylene block copolymers, polyoxyethylene ethers of glycerin esters, fatty acid alkylolamides, and glycerin fatty acid esters.

[0160] <Packaging container> Finally, a packaging container including the sheet welding structure 1 according to this embodiment will be described. Fig. 21 is a perspective view showing a packaging container including the sheet welding structure according to this embodiment. Fig. 22 is a perspective view showing a packaging container including the sheet welding structure according to this embodiment in a partially unfolded state.

[0161] 21 and 22, the pack container 200 includes a body portion 210, a top surface portion 220, and a bottom surface portion 230. The pack container 200 may be substantially made up of the sheet S only.

[0162] The body 210 of the pack container 200 can be formed from the same sheet S as the sheet S used to manufacture the tube container 100. The body 210 has a rectangular cylindrical shape. Like the tube container 100, the body 210 can have a side seal portion (not shown) including the sheet welding structure 1 on the back or front.

[0163] The top surface portion 220 and the bottom surface portion 230 close one end and the other end, respectively, of the rectangular cylindrical body portion 210. The top surface portion 220 and the bottom surface portion 230 can be formed by welding the inner surfaces of one end and the other end of a sheet S formed into a cylindrical shape to form the body portion 210. More specifically, the top surface portion 220 and the bottom surface portion 230 can be formed by folding the portion of the sheet S formed in this manner that is located on one side of the body portion 210 and the portion that is located on the other side of the body portion 210, respectively.

[0164] The top surface portion 220 may have a first end seal portion 221. The first end seal portion 221 may have a configuration that may be included in the end seal portion 130 of the tube container 100. In other words, the first end seal portion 221 may have the sheet welding structure 1 according to this embodiment.

[0165] The bottom portion 230 may have a second end seal portion 231. The second end seal portion 231 may have a configuration that may be included in the end seal portion 130 of the tube container 100. In other words, the second end seal portion 231 may have the sheet welding structure 1 according to this embodiment.

[0166] (Additional Notes) As described above, the embodiments of the present invention include the following disclosures.

[0167] <Configuration 1> A film containing a polyester resin and having a thickness of a １ a first sheet portion containing a polyester resin and having a thickness of a ２ and a second sheet portion having a shape of: overlapping a first sheet portion and a second sheet portion having a shape of: in a thickness direction, pressing the first sheet portion from one side in the thickness direction with a first member against the overlapping first sheet portion and the second sheet portion from the other side in the thickness direction with a second member, thereby welding the first sheet portion and the second sheet portion to each other, wherein the first member is one of an anvil and an ultrasonic horn, and has a first pressing surface that presses the first sheet portion, and the second member is the other of the anvil and the ultrasonic horn, and has a second pressing surface that presses the second sheet portion, and the first pressing surface comprises: one or more first surfaces that are arranged in a pattern when viewed from the first sheet portion when pressing by the first member is started, and that include a surface that is closest to the first sheet portion; and one or more second surfaces that are arranged in a pattern so as not to overlap with the first surface when viewed from the first sheet portion when the first member starts pressing, and that are located farther than the first surface and include a surface that is farthest from the first sheet portion, and when the distance in the thickness direction between the surface of the first surface that is closest to the first sheet portion and the surface of the second surface that is farthest from the first sheet portion when the first member starts pressing the first sheet portion is b, and when the distance in the thickness direction between the second surface and the second pressing surface when the first member and the second member are closest to each other during welding of the first sheet portion and the second sheet portion is c', the following relational expressions (1) and (2) are satisfied: Method for manufacturing sheet welding structure.

[0168] <Configuration 2> Further satisfying the following relations (3) and (4): A method for manufacturing the sheet welding structure described in <Configuration 1>.

[0169] <Configuration 3> The method for manufacturing a sheet welding structure according to <Configuration 1> or <Configuration 2>, wherein the second surface and the second pressing surface are both flat.

[0170] <Configuration 4> A method for manufacturing a tube container having a body portion, comprising forming the body portion by molding a sheet including the first sheet portion and the second sheet portion into a cylindrical shape so as to form a side seal portion made of a sheet welding structure manufactured by the method for manufacturing a sheet welding structure described in any one of <Configuration 1> to <Configuration 3>.

[0171] <Configuration 5> A film containing a polyester resin and having a thickness of a １ and a first sheet portion containing a polyester resin and having a thickness of a ２ a sheet welding structure formed by overlapping second sheet portions, each of which is a first sheet portion and a second sheet portion, in the thickness direction so that the first sheet portion is located on one side in the thickness direction and the second sheet portion is located on the other side in the thickness direction, and welding the first sheet portion and the second sheet portion to each other, the sheet welding structure comprising: one or more thin portions that are arranged in a pattern when the sheet welding structure is viewed from the one side in the thickness direction and include portions of the sheet welding structure that are thinnest in the thickness direction; and one or more thick portions that are arranged in a pattern so as not to overlap the thin portions when the sheet welding structure is viewed from the one side in the thickness direction, and are thicker in the thickness direction than the thin portions and include portions of the sheet welding structure that are thickest in the thickness direction; and the following relational expressions (5) and (6) are satisfied when the thickness of the thickest portion of the thick portion is c and the thickness of the thinnest portion of the thin portion is d: Sheet welded structure.

[0172] <Configuration 6> Further satisfying the following relations (7) and (8): The sheet welding structure according to <Configuration 5>.

[0173] <Configuration 7> The sheet welding structure according to <Configuration 5> or <Configuration 6>, wherein both surfaces of the thick portion are flat.

[0174] <Configuration 8> A tube container having a body portion, wherein the body portion is formed by shaping a sheet including the first sheet portion and the second sheet portion into a cylindrical shape, and the tube container has the sheet welding structure described in any one of <Configuration 5> to <Configuration 7> as a side seal portion.

[0175] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0176] DESCRIPTION OF SYMBOLS 1, 1x, 1y Sheet welding structure, 10, 10x, 10y Thin portion, 12 First structural surface, 13 Second structural surface, 20, 20x, 20y Thick portion, 22 Third structural surface, 23 Fourth structural surface, 30 Connection portion, 31 Fifth structural surface, 32 First edge, 33 Second edge, 34 Sixth structural surface, 40 First extending sheet portion, 50 Second extending sheet portion, 100 Tube container, 110 Body portion, 111 Main body portion, 112 Side seal portion, 113 One end portion, 114 Other end portion, 120 Spout portion, 130 End seal portion, 140 Cap portion, 200 Pack container, 210 Body portion, 220 Top surface portion, 221 First end seal portion, 230 Bottom surface portion, 231 Second end seal portion, AL Adhesive layer, BL1 First barrier layer, BL2 Second barrier layer, M1, M1x First members M11y, M11x, M11 First pressing surface, M11a, M11ax First surface, M11b, M11bx Second surface, M11cy, M11c Third surface, M12 First edge, M13 Second edge, M2 Second member, M21 Second pressing surface, M3 Third member, M4 Fourth member, ML Integrated layer, MX1 First mixed portion, MX2 Second mixed portion, RL1 First reinforcing layer, RL2 Second reinforcing layer, S Sheet, SE2 Second end surface, SL1 First base material layer, SL2 Second base material layer, SL3, SL3z Third base material layer, SL4, SL4z Fourth base material layer, SP1 First sheet portion, SP2 Second sheet portion.

Claims

1. Contains polyester resin and has a thickness of a １ a first sheet portion containing a polyester resin and having a thickness of a ２ and a second sheet portion having a shape of: overlapping a first sheet portion and a second sheet portion having a shape of: in a thickness direction, pressing the first sheet portion from one side in the thickness direction with a first member against the overlapping first sheet portion and the second sheet portion from the other side in the thickness direction with a second member, thereby welding the first sheet portion and the second sheet portion to each other, wherein the first member is one of an anvil and an ultrasonic horn, and has a first pressing surface that presses the first sheet portion, and the second member is the other of the anvil and the ultrasonic horn, and has a second pressing surface that presses the second sheet portion, and the first pressing surface comprises: one or more first surfaces that are arranged in a pattern when viewed from the first sheet portion when pressing by the first member is started, and that include a surface that is closest to the first sheet portion; and one or more second surfaces that are arranged in a pattern so as not to overlap with the first surface when viewed from the first sheet portion when the first member starts pressing, and that are located farther than the first surface and include a surface that is farthest from the first sheet portion, and when the distance in the thickness direction between the surface of the first surface that is closest to the first sheet portion and the surface of the second surface that is farthest from the first sheet portion when the first member starts pressing the first sheet portion is b, and when the distance in the thickness direction between the second surface and the second pressing surface when the first member and the second member are closest to each other during welding of the first sheet portion and the second sheet portion is c', the following relational expressions (1) and (2) are satisfied: Method for manufacturing sheet welding structure.

2. Further satisfy the following relations (3) and (4): A method for manufacturing the sheet welding structure of claim 1.

3. The method for manufacturing a sheet welding structure according to claim 1, wherein the second surface and the second pressing surface are both flat.

4. A method for manufacturing a tube container having a body portion, comprising forming the body portion by molding a sheet including the first sheet portion and the second sheet portion into a cylindrical shape so as to form a side seal portion consisting of a sheet welding structure manufactured by the method for manufacturing a sheet welding structure described in any one of claims 1 to 3.

5. Contains polyester resin and has a thickness of a １ and a first sheet portion containing a polyester resin and having a thickness of a ２ a sheet welding structure formed by overlapping second sheet portions, each of which is a first sheet portion and a second sheet portion, in the thickness direction so that the first sheet portion is located on one side in the thickness direction and the second sheet portion is located on the other side in the thickness direction, and welding the first sheet portion and the second sheet portion to each other, the sheet welding structure comprising: one or more thin portions that are arranged in a pattern when the sheet welding structure is viewed from the one side in the thickness direction and include portions of the sheet welding structure that are thinnest in the thickness direction; and one or more thick portions that are arranged in a pattern so as not to overlap the thin portions when the sheet welding structure is viewed from the one side in the thickness direction, and are thicker in the thickness direction than the thin portions and include portions of the sheet welding structure that are thickest in the thickness direction; and the following relational expressions (5) and (6) are satisfied when the thickness of the thickest portion of the thick portion is c and the thickness of the thinnest portion of the thin portion is d: Sheet welded structure.

6. Further satisfy the following relations (7) and (8): The sheet welding structure according to claim 5 .

7. The sheet welding structure according to claim 5, wherein both surfaces of said thick portion are flat.

8. A tube container having a body portion, wherein the body portion is formed by shaping a sheet including the first sheet portion and the second sheet portion into a cylindrical shape, and the tube container has a sheet welding structure as described in any one of claims 5 to 7 as a side seal portion.

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