JP7792470B2 - Two-layer bag, manufacturing method and manufacturing device thereof, and bagged body - Google Patents

Description

The present invention relates to two-layer bags, their manufacturing methods and manufacturing equipment, and bagged products using the two-layer bags.

Two-layer bags have been known as strong, flexible bags, having an inner layer forming an inner bag and an outer layer forming an outer bag, with the inner and outer layers bonded only in a partial area. These conventional two-layer bags have a cylindrical body with an opening at one end and a closed other end, and have a double-layered body consisting of an inner tubular portion formed by the inner layer and an outer tubular portion formed by the outer layer.

As an example of a conventional two-layer bag, Patent Document 1 below discloses a multi-layer bag. This multi-layer bag is made by stacking multiple rectangular sheets of material, joining two opposing edges together to form a tube, flattening the joined edges so that they are positioned approximately in the center, and joining all of the material together at one end of the tube to form the multi-layer bag. The material on the side of the bag opposite the edge that was originally joined together to form the tube is then joined in one or more linear lines that are approximately parallel to the edge that was originally joined together to form the tube.

Japanese Utility Model Publication No. 57-34991

However, in the conventional two-layer bag, the inner and outer layers are only bonded near the opening at the body seal and the one or more seams. As a result, in the conventional two-layer bag, the inner and outer layers are separated by a relatively large distance near the opening, which can lead to the risk of contents accidentally getting stuck between the inner and outer layers.

The present invention was made in light of these circumstances, and aims to provide a two-layer bag in which the inner and outer layers are less likely to separate near the opening, reducing the risk of contents accidentally getting between the inner and outer layers, as well as a manufacturing method and device for the bag, and a bagged product using the two-layer bag.

The following aspects are presented as means for solving the above-mentioned problems. A two-layer bag according to a first aspect has an inner layer forming an inner bag and an outer layer forming an outer bag, with the inner and outer layers bonded only in a partial region. The bag has a cylindrical body portion with an opening at one end and a closed other end, and has a double structure consisting of an inner cylindrical portion formed by the inner layer and an outer cylindrical portion formed by the outer layer. Incisions are formed in the inner and outer cylindrical portions from the edges of the cylindrical portions corresponding to the edges of the opening toward the other end of the body. The partial region includes an opening-side region bonded with adhesive. The opening-side region is positioned to avoid any of the incisions. The opening-side region is positioned so that the entire edge of the opening abuts somewhere in the opening-side region when the edge of the opening is virtually moved toward the other end of the body. A portion of the opening-side region is positioned closer to the edge of the opening than either tip of the incisions.

These notches may be formed in two-layer bags for a variety of reasons. For example, when forming a square bottom using a notch, when the notch for forming the square bottom is made on the bottom side, the same notch may also be made on the opening side of an adjacent two-layer bag that is being produced in succession.

According to the first aspect, the partial region includes the opening-side region, and the opening-side region is positioned so that when the edge of the opening is virtually moved toward the other end of the body, the entire edge of the opening comes into contact with some point in the opening-side region. Therefore, there is no risk of contents accidentally getting between the inner and outer layers further toward the bottom (toward the other end of the body) than the opening-side region.

Unlike the first aspect, if the opening-side region is configured solely from a circumferential region that continuously encircles the body at a position farther from the edge of the opening toward the other end of the body than either of the incisions, the circumferential region is positioned further from the edge of the opening toward the other end of the body than either of the incisions, and there is a limit to how close the circumferential region can be to the edge of the opening. Therefore, if the opening-side region is configured solely from the circumferential region, there is a high risk of the contents being accidentally trapped between the inner and outer layers between the circumferential region and the edge of the opening. However, according to the first aspect, a portion of the opening-side region is positioned closer to the edge of the opening than the tips of either of the incisions, thereby reducing the risk of the contents being accidentally trapped between the inner and outer layers compared to when the opening-side region is configured solely from the circumferential region. Furthermore, according to the first aspect, the opening side area avoids the incisions, so even if the incisions are formed after adhesive has been applied, there is no risk of the adhesive sticking to the blade forming the incisions and causing problems, and even if adhesive is applied after the incisions are formed, there is no risk of the adhesive leaking from the incisions to the back side of the application surface and causing problems.

In this way, according to the first aspect, even though the incisions are formed, it is possible to significantly reduce the risk of contents accidentally getting between the inner and outer layers, provided that there is no risk of adhesive sticking to the blades that form the incisions and causing problems during manufacturing, or of adhesive leaking from the incisions to the back of the application surface and causing problems.

The two-layer bag according to the second aspect is the same as the bag according to the first aspect, except that the opening-side region includes a circumferential region that continuously circumferentially surrounds the body from the edge of the opening toward the other end of the body at a position farther than any of the incisions, and a region located between the edge of the opening and the circumferential region.

This second aspect is an example of the opening-side region, but the first aspect is not limited to this example.

The two-layer bag according to the third aspect is the same as the bag according to the second aspect, except that the region located between the edge of the opening and the circumferential region is a region that circumferentially surrounds the body.

In this third aspect, the region located between the edge of the opening and the circumferential region is a region that intermittently circumferentially surrounds the body, which significantly reduces the risk of contents accidentally getting between the inner and outer layers compared to when the region located between the edge of the opening and the circumferential region is a small portion of the body's circumference. However, in the second aspect, the region located between the edge of the opening and the circumferential region may be a small portion of the body's circumference.

The two-layer bag according to the fourth aspect is a bag according to any one of the first to third aspects that does not have a heat-sealed adhesive portion. In the first to third aspects, it is not necessary for the bag to have a heat-sealed adhesive portion, as in the third aspect, or it may have a heat-sealed adhesive portion.

The two-layer bag according to the fifth aspect is any one of the first to fourth aspects, but is provided with a square bottom that closes the other end of the body.

This fourth aspect uses a square-bottom bag as an example of the bag shape. However, the first to fourth aspects do not necessarily have to have a square bottom.

A two-layer bag according to a sixth aspect has an inner layer forming an inner bag and an outer layer forming an outer bag, with the inner and outer layers bonded only in a partial region. The bag has a tubular body with an opening at one end and a closed other end, and has a double-layered structure consisting of an inner tubular portion formed by the inner layer and an outer tubular portion formed by the outer layer. Band-like regions extending in the lengthwise direction of the inner tubular portion are heat-sealed to each other so that the inner layer forms the inner tubular portion. The partial region includes a surrounding region that continuously wraps around the body near the edge of the opening and is bonded with an adhesive.

As far as the inventors know, there have been no two-layer bags in which band-shaped regions extending in the longitudinal direction of the inner tubular portion are heat-sealed together, and the partial region includes the circumferential region. This is presumably due to circumstances such as those described in the first comparative example below. As a result of research, the inventors discovered that the two-layer bag according to the sixth aspect can be realized using the manufacturing method according to the tenth aspect described below, and thus invented the two-layer bag according to the sixth aspect.

According to the sixth aspect, even though the band-shaped regions extending in the longitudinal direction of the inner tubular portion are heat-sealed to each other, the partial region includes the circumferential region, thereby reducing the risk of contents accidentally getting between the inner and outer layers.

The two-layer bag according to the seventh aspect is the same as the sixth aspect, except that one surface of the inner layer is heat-sealable and the other surface of the inner layer is non-heat-sealable (i.e., not heat-sealable), and a strip-shaped portion along one side of the inner layer extending in the length direction of the inner tubular portion is folded back so that the one surface faces outward and the folded state is maintained by adhesive, and the strip-shaped portion is heat-sealed to a strip-shaped region along the other side of the inner layer extending in the length direction of the inner tubular portion.

According to this seventh aspect, the inner layer can be affixed to the body in an envelope-like manner rather than a hem-and-shoulder style.

The two-layer bag according to the eighth aspect is the sixth or seventh aspect, and is provided with a square bottom that closes the other end of the body.

This eighth aspect uses a square-bottom bag as an example of the bag shape. However, the sixth and seventh aspects do not necessarily have to have a square bottom.

The bagged product according to the ninth aspect uses a two-layer bag according to any one of the first to eighth aspects, with the desired contents placed inside the inner bag and the opening closed.

The two-layer bag manufacturing method according to the tenth aspect is a manufacturing method for manufacturing a two-layer bag according to any one of the sixth to eighth aspects, in which the adhesive for bonding the circumferential region is applied to a first sheet forming the continuous outer layer, and the first and second sheets are guided so that the adhesive applied to the first continuous sheet does not transfer to the intended facing region of the second sheet forming the continuous inner layer, until the intended facing region that will face the heater bar that performs the heat sealing has passed the point facing the heater bar.

According to this tenth aspect, two-layer bags according to the sixth to eighth aspects can be manufactured without the inconveniences that arise when using the manufacturing apparatus shown in Figure 16, which will be described later.

The two-layer bag manufacturing apparatus according to the eleventh aspect is a two-layer bag manufacturing apparatus used to manufacture the two-layer bags according to any one of the sixth to eighth aspects, and includes an application unit that applies the adhesive that bonds the circumferential region to a first sheet that forms the continuous outer layer, and a guide unit that guides the first and second sheets so that the adhesive applied to the first continuous sheet does not transfer to the intended facing region of the second sheet that forms the continuous inner layer, which will face the heater bar that performs the heat sealing, until the intended facing region has passed the point facing the heater bar.

According to this eleventh aspect, two-layer bags according to the sixth to eighth aspects can be manufactured without the inconveniences that arise when using the manufacturing apparatus shown in Figure 16, which will be described later.

The present invention provides a two-layer bag in which the inner and outer layers are less likely to separate near the opening, reducing the risk of contents accidentally getting between the inner and outer layers, as well as a manufacturing method and device for the bag, and a bagged product using the two-layer bag.

1 is a schematic perspective view showing a state in which the opening of a two-layer bag according to a first embodiment of the present invention is opened to a medium degree. FIG. 2 is a schematic perspective view showing the two-layer bag shown in FIG. 1 with the opening completely opened. FIG. 2A and 2B are a schematic front view and a schematic right side view showing the two-layer bag shown in FIG. 1 in a flattened state. 2 is a schematic cross-sectional view taken along line A-A' in FIG. 1. FIG. 5 is a schematic enlarged cross-sectional view of a portion B in FIG. 4 . This is a schematic cross-sectional view taken along line C-C' in Figure 1. FIG. 5 is a schematic enlarged cross-sectional view of a portion D in FIG. 4 . 2 is a schematic development view showing the outer layer of the two-layer bag shown in FIG. 1. 2 is a schematic development view showing the inner layer of the two-layer bag shown in FIG. 1. 2A and 2B are a schematic side view and a schematic plan view showing an example of a two-layer bag manufacturing apparatus used to manufacture the two-layer bag shown in FIG. 1 . 11A and 11B are a schematic enlarged side view and a schematic enlarged plan view showing the vicinity of the heater bar in FIG. 10 . 2 is a schematic rear view showing the process of forming the bottom of the two-layer bag shown in FIG. 1. 13 is a schematic rear view showing the process of forming the bottom of the two-layer bag shown in FIG. 1 after the state shown in FIG. 12. 14 is a schematic rear view showing the process of forming the bottom of the two-layer bag shown in FIG. 1 after the state shown in FIG. 13. 2 is a schematic rear view showing the state after the formation of the bottom portion of the two-layer bag shown in FIG. 1 has been completed. FIG. 11A and 11B are a schematic side view and a schematic plan view showing a manufacturing apparatus according to a comparative example to be compared with the manufacturing apparatus shown in FIG. 10 . 17A and 17B are a schematic enlarged side view and a schematic enlarged plan view showing an example of the state in the vicinity of the heater bar in FIG. 16 . 17A and 17B are a schematic enlarged side view and a schematic enlarged plan view showing another example of the state in the vicinity of the heater bar in FIG. 16 . 2 is a schematic perspective view showing a state in which an opening of a two-layer bag according to a first comparative example, which is compared with the two-layer bag shown in FIG. 1, is opened to a moderate degree. FIG. FIG. 20 is a schematic perspective view showing the two-layer bag shown in FIG. 19 with the opening completely opened. This is a schematic cross-sectional view taken along line E-E' in Figure 19. FIG. 22 is a schematic enlarged cross-sectional view of a portion F in FIG. 21 . FIG. 10 is a schematic perspective view showing a state in which the opening of a two-layer bag according to a second embodiment of the present invention is opened to a moderate degree. FIG. 24 is a schematic perspective view showing the two-layer bag shown in FIG. 23 with the opening completely opened. 24A and 24B are a schematic front view and a schematic right side view showing the flattened state of the two-layer bag shown in FIG. 23. This is a schematic cross-sectional view taken along line G-G' in Figure 23. This is a schematic cross-sectional view taken along line H-H' in Figure 23. This is a schematic cross-sectional view taken along line I-I' in Figure 23. FIG. 24 is a schematic development view showing the outer layer of the two-layer bag shown in FIG. 23. FIG. 24 is a schematic development view showing the inner layer of the two-layer bag shown in FIG. 23. 24A and 24B are a schematic side view and a schematic plan view showing an example of a two-layer bag manufacturing apparatus used to manufacture the two-layer bag shown in FIG. 23. FIG. 32 is a schematic plan view showing a part of a continuous sheet of the outer layer in FIG. 31 . 32 is a schematic plan view showing a part of a continuous sheet of the inner layer in FIG. 31. FIG. 24 is a schematic rear view showing the process of forming the bottom of the two-layer bag shown in FIG. 23. 35 is a schematic rear view showing the process of forming the bottom of the two-layer bag shown in FIG. 23 after the state shown in FIG. 34. 36 is a schematic rear view showing the process of forming the bottom of the two-layer bag shown in FIG. 23 after the state shown in FIG. 35. 24 is a schematic rear view showing the state after the formation of the bottom of the two-layer bag shown in FIG. 23 has been completed. FIG. 24 is a schematic perspective view showing a state in which the opening of a two-layer bag according to a second comparative example, which is compared with the two-layer bag shown in FIG. 23, is opened to a moderate degree. 10A to 10C are partially enlarged schematic front views showing examples of patterns in the region on the opening side that is bonded with an adhesive.

The following describes the two-layer bag, its manufacturing method and manufacturing apparatus, and a bagged product using the two-layer bag according to the present invention, with reference to the drawings.

[First embodiment]

1 is a schematic perspective view of a two-layer bag 1 according to a first embodiment of the present invention, with the opening 2a moderately open. FIG. 2 is a schematic perspective view of the two-layer bag 1 shown in FIG. 1, with the opening 2a fully open. FIG. 3(a) is a schematic front view of the two-layer bag 1 shown in FIG. 1 in a flattened state. FIG. 3(b) is a schematic right side view of the two-layer bag 1 shown in FIG. 1 in a flattened state. Note that FIG. 3(b) omits the illustration of the right side portion 13, which constitutes the gusset portion. FIG. 4 is a schematic cross-sectional view taken along line A-A' in FIG. 1. FIG. 5 is a schematic enlarged cross-sectional view of portion B in FIG. 4. FIG. 6 is a schematic cross-sectional view taken along line C-C' in FIG. 1. FIG. 7 is a schematic enlarged cross-sectional view of portion D in FIG. 4. FIG. 8 is a schematic development of the outer layer 1A of the two-layer bag 1 shown in FIG. 1. FIG. 9 is a schematic development of the inner layer 1B of the two-layer bag 1 shown in FIG. 1.

In the following explanation, the front side of the page in Figure 1 will be referred to as the front side or front side, and the back side of the page in Figure 1 will be referred to as the rear side or rear side, but the reverse is also possible. Regarding "front" and "rear," which side is the "front" and which side is the "rear" are not fixedly determined, and if "front" refers to one side, "rear" means the opposite side.

The two-layer bag 1 of this embodiment has a cylindrical body 2 with an opening 2a at one end (the upper end in Figure 1) and a closed other end (the lower end in Figure 1). The two-layer bag 1 of this embodiment has a square bottom 3 that closes the lower end of the body 2, making it a square-bottom bag. However, the two-layer bag of this invention does not necessarily have to have a square bottom, and is not limited to square-bottom bags. Furthermore, the two-layer bag of this invention does not necessarily have a gusset portion (described below).

In this embodiment, the body 2 has a front portion 11, a back portion 12, and side portions 13, 14 forming gusset portions, and is configured in a rectangular cylindrical shape. Fold lines 13a-13d are formed on the right side 13 of the two-layer bag 1, and fold lines (not shown) similar to fold lines 13a-13d are formed on the left side 14 of the two-layer bag 1, allowing the two-layer bag 1 to be folded flat as shown in Figure 3. In this flat state, the opening 2a is closed. In the example shown in Figure 3, the square bottom portion 3 is folded toward the back portion 12, but the square bottom portion 3 may also be folded toward the front portion 11. This also applies to Figure 25, which will be described later.

1 to 3 show a single-layer bag, but as shown in FIGS. 4 to 9, the two-layer bag 1 of this embodiment is a two-layer bag having an inner layer 1B forming an inner bag and an outer layer 1A forming an outer bag, with the inner layer 1B and the outer layer 1A bonded only in a partial region. The body 2 of the two-layer bag 1 has a double structure consisting of an inner tubular portion made of the inner layer 1B and an outer tubular portion made of the outer layer 1A. In this embodiment, as shown in FIGS. 1, 2, and 4 to 7, the inner tubular portion made of the inner layer 1B and the outer tubular portion made of the outer layer 1A are bonded with adhesive 22 only in a circumferential region R2 that continuously circumferentially surrounds the body 2 near the edge of the opening 2a; the inner layer 1B and the outer layer 1A are not bonded in other locations on the body 2. Thus, in this embodiment, the partial region includes a surrounding region R2 that continuously surrounds the body 2 near the edge of the opening 2a and is adhered with adhesive 22.

The outer layer 1A is composed of a rectangular sheet when unfolded as shown in Figure 8, and has a layer structure of one or more layers (not shown). The inner layer 1B is also composed of a rectangular sheet when unfolded as shown in Figure 9, and has a layer structure of one or more layers (not shown). In this embodiment, one surface of the inner layer 1B (the surface on the far side of the page in Figure 9, i.e., the surface that mainly forms the inside of the two-layer bag 1) is heat-sealable, and the other surface of the inner layer 1B (the surface on the near side of the page in Figure 9, i.e., the surface that mainly forms the outside of the two-layer bag 1) is not heat-sealable.

The outer layer 1A can be a single-layer sheet made of one-sided gloss bleached kraft paper, with the side facing the page in Figure 8 (i.e., the side that will become the outside of the two-layer bag 1) being white. The inner layer 1B can be, for example, a four-layer sheet made of polyethylene/aluminum/polyethylene/unbleached kraft paper layered in this order from the one side, or a two-layer sheet made of polyethylene/unbleached kraft paper layered in this order from the one side. However, in the present invention, the outer layer 1A and inner layer 1B are not limited to these examples and can be modified as appropriate depending on the contents to be stored.

In Figure 8, the mountain fold lines of outer layer 1A are indicated by dashed lines, and the valley fold lines of outer layer 1A are indicated by broken lines. As shown in Figure 8, outer layer 1A has portion 2A, which becomes the outer tubular portion that forms body 2 of two-layer bag 1, and portion 3A, which forms corner bottom 3. The left side of outer layer 1A in Figure 8 corresponds to the edge of opening 2a of two-layer bag 1. Of portion 2A, portion 11A forms front portion 11 of two-layer bag 1, portion 12A forms back portion 12, portion 13A forms right portion (gore portion) 13, and portion 14A forms left portion (gore portion) 14. Portion 1Aa of the band-shaped region along the bottom edge of outer layer 1A in Figure 8 corresponds to the glue tab.

The band-shaped region R1 at the back of the page in FIG. 8, which extends along the top edge of the outer layer 1A near the top edge, is the region where adhesive 21 is applied. As shown in FIGS. 4 and 6, this adhesive 21 bonds the band-shaped region R1 of the outer layer 1A to the portion 1Aa, forming the outer tubular portion. The band-shaped region R2 at the back of the page in FIG. 8, which extends along the left edge of the outer layer 1A near the left edge, corresponds to the circumferential region R2 in FIGS. 1 and 2, and is the region where the adhesive 22 described above is applied. The regions R3 at the back of the page in FIG. 8, which are scattered near the left edge of the outer layer, are the region where adhesive 23 is applied, and adhesive 23 bonds the inner layer 1B and the outer layer 1A at the corner base 3. The partial region also includes this region R3.

In Figure 9, the mountain fold lines of the inner layer 1B are indicated by dashed lines, and the valley fold lines of the inner layer 1B are indicated by dashed lines. As shown in Figure 8, the inner layer 1B has a portion 2B that becomes the inner tubular portion that constitutes the body 2 of the two-layer bag 1, and a portion 3B that constitutes the corner bottom 3. The left side of the inner layer 1B in Figure 9 corresponds to the edge of the opening 2a of the two-layer bag 1. Of the portion 2B, portion 11B constitutes the front portion 11 of the two-layer bag 1, portion 12B constitutes the back portion 12, portion 13B constitutes the right portion (gore portion) 13, and portion 14B constitutes the left portion (gore portion) 14. The strip-shaped portion 1Ba along the bottom edge of the inner layer 1B in Figure 9 corresponds to the strip-shaped portion along one side of the inner layer 1B extending in the length direction of the inner tubular portion, and corresponds to the folded portion that is folded over to overlap the adjacent strip-shaped region 1Bb. The thin strip-shaped region of strip portion 1Ba on the front side of the paper in Figure 9 that extends along the lower edge of inner layer 1B in Figure 9 near the lower edge is the region to which adhesive 24 is applied. As shown in Figures 4 to 7, this adhesive 24 keeps strip portion 1Ba folded over strip region 1Bb.

The heat-sealable region of band-shaped portion 1Bc extending along the top edge of inner layer 1B in FIG. 9, located at the rear of the page in FIG. 9, is heat-sealed to the heat-sealable surface of band-shaped portion 1Ba, which is folded over band-shaped portion 1Bb with adhesive 24, as shown in FIGS. 4 and 6, to form the inner tubular portion. In FIGS. 4 and 6, the heat-sealed location between band-shaped portion 1Bc and folded-over band-shaped portion 1Ba is indicated by the reference numeral 25.

Figure 10(a) is a schematic side view showing an example of a two-layer bag manufacturing apparatus (bag making machine) 31 used to manufacture the two-layer bag 1 shown in Figure 1. In Figure 10(a), the thick dashed line shows the path of the continuously transported outer layer sheet 1A', and the thick solid line shows the path of the continuously transported inner layer sheet 1B'. Figure 10(b) is a schematic plan view showing some elements 43, 52, 53 of the manufacturing apparatus 31, as well as the outer layer sheet 1A' and inner layer sheet 1B'.

The manufacturing device 31 includes a sheet supply section 32, a folding and coating section 33, a cylindrical forming and heat sealing section 34, a cutting section 35, a bottom folding section 36, and an accumulation section 37.

The sheet supply unit 32 supports an outer layer sheet roll 1A" around which an outer layer sheet (first sheet) 1A' is wound as a raw web, and an outer layer sheet roll 1A" around which an inner layer sheet (second sheet) 1B' is wound as a raw web, and unwinds the outer layer sheet 1A' from the outer layer sheet roll 1A" and unwinds the inner layer sheet 1A' from the inner layer sheet roll 1B", supplying them to be transported in the transport direction X. At this time, the sheet supply unit 32 supplies the outer layer sheet 1A' and the inner layer sheet 1B' so that the inner layer sheet 1B' overlaps the outer layer sheet 1A', with the outer layer sheet and the inner layer sheet 1B' offset by a predetermined distance in the lateral direction (a direction perpendicular to the transport direction X).

Outer layer sheet 1A' corresponds to a continuous body (first sheet forming a continuous body of outer layers 1A) in which outer layers 1A shown in Figure 8 are successively connected in the transport direction X. However, in Figure 10(b), the state from outer layer sheet roll 1A" to guide roller 41 corresponds to outer layer 1A shown in Figure 8 being flipped over, with the left and right sides reversed. Therefore, the front side of the paper in Figure 10(b) corresponds to the back side of the paper in Figure 8.

The inner layer sheet 1B' corresponds to a continuous body (a second sheet forming a continuous body of inner layers 1B) in which the inner layers 1B shown in Figure 9 are successively connected in the transport direction X. However, in Figure 10(b), the state from the inner layer sheet roll 1B" to the guide roller 41 corresponds to the inner layer 1A shown in Figure 9 reversed left to right. Therefore, in this state, the front side of the paper in Figure 10(b) corresponds to the back side of the paper in Figure 9. For this reason, in this state, the surface of inner layer sheet 1B' facing the front side of the paper in Figure 10(b) is heat-sealable, and the surface of inner layer sheet 1B' facing the back side of the paper in Figure 10(b) is not heat-sealable. Inner layer sheet 1B' overlaps outer layer sheet 1A' on the front side of the paper in Figure 10(b). The outer layer sheets 1A' and inner layer sheets 1B' are shifted laterally by the specified distance so that the lateral positions of portion 11A of outer layer 1A constituting front surface portion 11 in Figure 8 and portion 11B of inner layer 1B constituting front surface portion 11 in Figure 9 coincide with each other.

As shown in Figure 10, the folding/application section 33 includes guide rollers 41, 42, 44, 45, 46, and 51, an application nozzle 43 that applies adhesive 24 to region R4 of the inner layer 1B in Figure 9, a folding mechanism (not shown) that folds back the band-shaped portion 1Ba along the lower edge of the inner layer 1B in Figure 9 so that it overlaps band-shaped region 1Bb, an application device that applies adhesives 22 and 23 to regions R2 and R3 of the outer layer 1A in Figure 8, respectively, and an application nozzle 52 that applies adhesive 21 to region R1 of the outer layer 1A in Figure 8. The applicator that applies adhesives 22 and 23 to regions R2 and R3 of outer layer 1A in Figure 8 includes a container 47 that contains adhesive to become adhesives 22 and 23, a take-out roller 48 that takes the adhesive from container 47, and an applicator roller 49 made of rubber or the like that applies the adhesive taken out by the take-out roller 48 to outer layer sheets 1A'R22 and R23 that pass between it and a receiving roller 50.

As shown in FIG. 10, after adhesive 24 is applied to region R4 of inner layer sheet 1B' by application nozzle 43, strip portion 1Ba is folded back, and then the sheet leaves folding and application section 33 and enters cylindrical forming and heat sealing section 34. Meanwhile, after adhesives 22 and 23 are applied to regions R2 and R3 of outer layer sheet 1A' by application roller 49, adhesive 24 is applied to region R1 by application nozzle 52, and then the sheet leaves folding and application section 33 and enters cylindrical forming and heat sealing section 34.

Inner layer sheet 1B' remains completely flat until strip portion 1Ba is folded back, and after strip portion 1Ba is folded back, it remains flat in that folded state until it passes guide roller 45. Outer layer sheet 1A' remains completely flat until it passes guide roller 52. In this manufacturing device 31, guide rollers 41, 42, 44, 45, 46, 51, etc., serve as guide members, so that inner layer sheet 1B' and outer layer sheet 1A' are completely separated without contact from guide roller 41 to position P within cylindrical forming/heat sealing section 34.

The cylindrical forming and heat sealing unit 34 forms the inner layer sheet 1B' and the outer layer sheet 1A' into a cylindrical shape and folds them, completing the bonding of each part with adhesives 21, 22, and 23. The cylindrical forming and heat sealing unit 34 has a forming member that performs the above-mentioned forming, but this is not shown. The cylindrical forming and heat sealing unit 34 has a heater bar 53 that heat seals the cylindrically folded inner layer sheet 1B' between the band-shaped portions 1Ba and 1Bc in Figure 9 (see also heat-sealed portion 25 in Figures 4 to 7). The heat sealing process is shown in Figure 11.

Figure 11(a) is a schematic enlarged side view showing the area around heater bar 53 in Figure 10. Figure 11(b) is a schematic enlarged plan view showing the area around heater bar 53 in Figure 10. In Figure 11(b), R53 indicates the area of inner layer sheet 1B' that will face heater bar 53 as it is transported, and R53' indicates the area of inner layer sheet 1B' that has passed the point facing heater bar 53. As shown in Figure 11(a), heater bar 53 is slightly tilted so that its outlet end (lower left end in Figure 11(a)) comes into contact with inner layer sheet 1B' and its inlet end leaves a slight gap between it and inner layer sheet 1B'.

From position P in Figure 10(a) onward, the cylindrical forming/heat sealing section 34 maintains the overlapping state of portion 11B of inner layer sheet 1B' (Figure 9) in contact with portion 11A of outer layer sheet 1A' (Figure 8), and raises both sides of portion 11B of inner layer sheet 1B' to form a cylindrical shape, while also raising both sides of portion 11A of outer layer sheet 1A' to form a cylindrical shape. At this time, the cylindrical folding of inner layer sheet 1B' is completed before inner layer sheet 1B' reaches heater bar 53. Meanwhile, as shown in Figure 11, portions 12A and the like of outer layer sheet 1A' (Figure 8) are not yet overlapping with inner layer sheet 1B' until they pass heater bar 53, but after passing heater bar 53, they overlap with inner layer sheet 1B' and are completely formed into a cylindrical shape. This ensures that in this manufacturing apparatus 31, the adhesive 22 applied to region R1 of outer sheet 1A' by applicator roller 49 does not transfer to the intended facing region R53 of inner sheet 1B' on the top surface (including intended facing region R53) of cylindrically folded inner sheet 1B' until it has passed the point facing heater bar 53. However, to ensure this, if necessary, a guide member (for example, a thin metal wire such as a wire with a certain degree of rigidity; not shown) may be used to guide one or both of outer layer sheet 1A' and inner layer sheet 1B' so that inner layer sheet 1B', which forms the top surface of cylindrically folded inner layer sheet 1B', does not come into contact with region R1 of outer layer sheet 1A'.

The outer layer sheet 1A' is then formed into a complete cylindrical shape by the tubular forming/heat sealing unit 34, passing through the heater bar 53. Once the outer layer sheet 1A' and inner layer sheet 1B' form a complete cylindrical body, this cylindrical body passes through guide rollers 54 and is cut into cylindrical bodies 1' for one two-layer bag 1 by the cutting unit 35. One end of each cylindrical body 1' for one two-layer bag 1 is folded by the bottom folding unit 36 into the folded state shown in Figure 12 (the folded state during the process of forming the square bottom 3). The cylindrical bodies 1' in the folded state shown in Figure 12 are accumulated in the accumulation unit 37.

The cylindrical body 1' shown in Figure 12 accumulated in the accumulation section 37 is a semi-finished two-layer bag 1, but will be the product of the manufacturing apparatus 31. The manufacturing apparatus 31 can be realized, for example, by modifying a portion of a known bag-making machine (for example, by adding or repositioning guide rollers or adding the metal wire described above to guide the inner layer sheet 1B' and outer layer sheet 1A' so that the adhesive 21 applied to region R2 of the outer layer sheet 1A' does not transfer to the intended facing region R53 of the inner layer sheet 1B' that will face the heater bar 53 until the intended facing region R53 has passed the point facing the heater bar 53).

Figure 12 is a schematic rear view showing the process of forming the bottom 3 of the two-layer bag shown in Figure 1. Figure 13 is a schematic rear view showing the process of forming the bottom 3 of the two-layer bag 1 shown in Figure 1 after the state shown in Figure 12. Figure 14 is a schematic rear view showing the process of forming the bottom 3 of the two-layer bag 1 shown in Figure 1 after the state shown in Figure 13. Figure 15 is a schematic rear view showing the state after formation of the bottom 3 of the two-layer bag 1 shown in Figure 1 has been completed.

The cylindrical body 1' shown in Figure 12 is folded as shown in Figure 13 by a known bottom forming device (not shown), and region R61 in the figure is heat-sealed. It is then folded as shown in Figure 14, and a bottom sheet 3a made of paper or the like is attached as shown in Figure 15. This completes the two-layer bag 1 shown in Figure 1. The manufacturing device 31 shown in Figure 10 and the bottom forming device may also be integrated to form a manufacturing device that performs all processes continuously.

The two-layer bag 1 according to this embodiment is manufactured, for example, by a bag manufacturer and supplied to a manufacturer of the contents. The manufacturer places the desired contents into the body 2 through the opening 2a at the top of the body 2, and then closes the opening 2a to complete the bag. Any method can be used to close the opening 2a, but one method may involve, for example, folding both side sections 13, 14 over to flatten the opening 2a, then rolling the opening 2a and gluing it at predetermined points with an adhesive to maintain the folded state. The contents are not limited in any way and may be, for example, pesticides, food, medicines, powders, liquids, solids, etc.

In the two-layer bag 1 according to this embodiment, although the band-shaped regions 1Ba, 1Bc extending along the length of the inner tubular portion of the inner layer sheet 1B' are heat-sealed to each other, they are bonded with adhesive 22 in the surrounding region R2 that continuously encircles the body portion 2 near the edge of the opening 2a, thereby reducing the risk of contents accidentally getting between the inner and outer layers.

Figure 16(a) is a schematic side view of a comparative manufacturing apparatus 61, which is compared with the manufacturing apparatus 31 shown in Figure 10, and corresponds to Figure 10(a). Figure 16(b) is a schematic plan view of some elements 43, 52, 53 of the manufacturing apparatus 61, as well as the outer layer sheet 1A' and inner layer sheet 1B', and corresponds to Figure 10(b). In Figure 16, elements that are the same as or correspond to elements in Figure 10 are given the same reference numerals, and redundant explanations will be omitted.

The manufacturing apparatus 61 shown in Figure 16 differs from the manufacturing apparatus 31 shown in Figure 10 mainly in that the guide roller 51 is removed, and the flat outer layer sheet 1A' after adhesive 22 has been applied to region R2 by the application roller 49 is also guided to the guide roller 45, where the flat outer layer sheet 1A' and the flat inner layer sheet 1B' after the belt-shaped portion 1Ba has been folded back come into contact and are temporarily superimposed on the guide roller 45, and that an application nozzle 52 that applies adhesive 21 to region R1 of the outer layer 1A is positioned near the guide roller 45.

In the manufacturing apparatus 61 shown in FIG. 16 , after adhesive 22 is applied to region R2 by the application roller 49, the flat outer layer sheet 1A' is brought into contact with the flat inner layer sheet 1B' after the strip-shaped portion 1Ba is folded back on the guide roller 45, and the flat outer layer sheet 1A' is then superimposed on the guide roller 45. Therefore, the entire area of the folded flat inner layer sheet 1B' that overlaps region R2 of the outer layer sheet 1A' on the guide roller 45 becomes an adhesive-transferable region R2' to which the adhesive 22 applied to region R2 can be transferred. As shown in FIG. 17(b), this adhesive-transferable region R2' also includes the upper surface of the cylindrically folded inner layer sheet 1B' (the surface facing the page in FIG. 17(b)).

Figure 17(a) is a schematic enlarged side view showing an example of the state near heater bar 53 in Figure 16, and corresponds to Figure 11(a). Figure 17(b) is a schematic enlarged plan view showing an example of the state near heater bar 53 in Figure 16, and corresponds to Figure 11(b). In Figure 17, elements that are the same as or correspond to elements in Figure 11 are given the same reference numerals, and redundant explanations will be omitted.

Therefore, as shown in Figure 17(b), a portion of the adhesive-transferable region R2' overlaps with the intended facing region R53 that will face the heater bar 53. As shown in Figure 17(a), if adhesive 22' resulting from the transfer of adhesive 22 is present in this overlapping region, this adhesive 22' will accumulate in the gap between the inner layer sheet 1B' and the heater bar 53 and be pushed out to the tip of the heater bar 53, as shown in Figure 17, causing problems with the two-layer bag 1. These problems include the adhesive 22' forming clumps and being mixed into the two-layer bag 1, the inner layer sheet 1B' being rubbed and damaged or torn, and the adhesive being scraped off from the overlapping region, preventing adhesion between the inner layer 1B and the outer layer 1A in that region.

To avoid this problem when using the manufacturing apparatus 61 shown in FIG. 16, it is necessary to remove a portion of the region R2 of the outer layer sheet 1A' where the adhesive 22 is applied by the application roller 49 so that the adhesive transferable region R2' does not overlap with the intended facing region R53, as shown in FIG. 18. In this case, the transferred adhesive 22, i.e., adhesive 22', is not present in the intended facing region R53, and the above-mentioned problem does not occur. FIG. 18(a) is a schematic enlarged side view showing another example of the state near the heater bar 53 in FIG. 16, and corresponds to FIGS. 11(a) and 17(a). FIG. 18(b) is a schematic enlarged plan view showing another example of the state near the heater bar 53 in FIG. 16, and corresponds to FIGS. 11(b) and 17(b). In FIG. 18, elements that are the same as or correspond to elements in FIGS. 11 and 17 are designated by the same reference numerals, and redundant explanations will be omitted.

A two-layer bag 71 according to a first comparative example manufactured in this manner is shown in Figures 19 to 22. Figure 19 is a schematic perspective view of a two-layer bag 71 according to a first comparative example, compared to the two-layer bag 1 shown in Figure 1, with the opening 2a moderately opened, and corresponds to Figure 1. Figure 20 is a schematic perspective view of the two-layer bag 71 shown in Figure 19 with the opening 2a fully opened, and corresponds to Figure 2. Figure 21 is a schematic cross-sectional view taken along line E-E' in Figure 19, and corresponds to Figure 6. Figure 22 is a schematic enlarged cross-sectional view of part F in Figure 21, and corresponds to Figure 7. In Figures 19 to 22, elements that are the same as or correspond to elements in Figures 1 to 7 are designated by the same reference numerals, and redundant explanations will be omitted.

In this first comparative example, the adhesive 22 is attached to the body 2 in a missing region R2 near the edge of the opening 2a, rather than going around the body 2. This means that contents can accidentally enter between the outer layer 1A and the inner layer 1B through the missing portion of region R2.

As such, as long as a manufacturing apparatus 61 such as that shown in Figure 16 is used, it is not possible to avoid the above-mentioned disadvantages by bonding the body portion 2 with adhesive 22 in the circumferential region R2 that continuously circumferentially surrounds the body portion 2 near the edge of the opening 2a, as in the two-layer bag 1 of this embodiment. This is presumably the reason why, as far as the inventors know, there have been no two-layer bags in which strip-shaped regions extending in the lengthwise direction of the inner tubular portion are heat-sealed together, with the partial region including the circumferential region.

In contrast, as described above, the manufacturing apparatus 31 shown in FIG. 10 ensures that the adhesive 22 applied to region R1 of the outer layer sheet 1A' by the application roller 49 does not transfer to the intended facing region R53 of the inner layer sheet 1B' on the upper surface of the cylindrically folded inner layer sheet 1B' (including the intended facing region R53) until the upper surface passes the point facing the heater bar 53. Therefore, even though the band-shaped regions 1Ba and 1Bc extending along the length of the inner tubular portion of the inner layer 1B are heat-sealed together, the manufacturing apparatus 31 shown in FIG. 10 can produce the two-layer bag 1 of this embodiment, bonded with adhesive 22 in the surrounding region R2 that continuously encircles the body portion 2 near the edge of the opening 2a, without the above-mentioned inconvenience. Incidentally, in FIG. 11, the upper surface of the cylindrically folded inner layer sheet 1B' does not have an adhesive-transferable region R2' to which the adhesive 22 applied to region R2 could transfer.

In the two-layer bag 1 of this embodiment, although the band-shaped regions 1Ba, 1Bc extending along the length of the inner tubular portion of the inner layer 1B are heat-sealed to each other, they are bonded with adhesive 22 in the surrounding region R2 that continuously encircles the body portion 2 near the edge of the opening 2a. This reduces the risk of contents accidentally getting between the inner and outer layers compared to the two-layer bag 71 of the first comparative example.

[Second embodiment]

Figure 23 is a schematic perspective view of a two-layer bag 81 according to a second embodiment of the present invention, with the opening 2a moderately open, corresponding to Figure 1. Figure 24 is a schematic perspective view of the two-layer bag 81 shown in Figure 23 with the opening 2a fully open, corresponding to Figure 2. Figure 25(a) is a schematic front view of the two-layer bag 81 shown in Figure 23 in a flattened state, corresponding to Figure 3(a). Figure 25(b) is a schematic right side view of the two-layer bag 81 shown in Figure 23 in a flattened state, corresponding to Figure 3(b). Figure 26 is a schematic cross-sectional view taken along line G-G' in Figure 23, corresponding to Figure 4. Figure 27 is a schematic cross-sectional view taken along line H-H' in Figure 23, corresponding to Figure 6. Figure 28 is a schematic cross-sectional view taken along line I-I' in Figure 23. Figure 29 is a schematic development view of the outer layer 1A of the two-layer bag 81 shown in Figure 23, corresponding to Figure 8. Figure 30 is a schematic development showing the inner layer 1B of the two-layer bag 81 shown in Figure 23, and corresponds to Figure 9. In Figures 23 to 30, elements that are the same as or correspond to elements in Figures 1 to 9 are given the same reference numerals, and redundant explanations will be omitted.

The two-layer bag 81 of this embodiment differs from the first two-layer bag 1 in the following ways:

Like the two-layer bag 1 according to the first embodiment, the two-layer bag 81 according to the present embodiment has an inner layer 1B forming an inner bag and an outer layer 1A forming an outer bag, with the inner layer 1B and the outer layer 1A being bonded only in a partial region. As with the first embodiment, the body 2 according to the present embodiment has a double structure consisting of an inner tubular portion made of the inner layer 1B and an outer tubular portion made of the outer layer 1A. In this embodiment, as shown in Figures 23, 24, 28, 29, and 30, the inner tubular portion made of the inner layer 1B has cuts 95b, 96b, 97b, and 98b formed from the edge of the tubular portion corresponding to the edge of the opening 2a toward the bottom 3. The outer tubular portion made of the outer layer 1A has cuts 91b, 92b, 93b, and 94b formed from the edge of the tubular portion corresponding to the edge of the opening 2a toward the bottom 3.

In this embodiment, as shown in Figures 23, 24, and 26 to 30, for the body 2, the inner tubular portion made of the inner layer 1B and the outer tubular portion made of the outer layer 1A are bonded with adhesive 22 in a circumferential region R2 that continuously circumferentially surrounds the body 2, and only a region R82 located closer to the edge of the opening 2a than the tips of any of the notches 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b is bonded with adhesive 82; the inner layer 1B and the outer layer 1A are not bonded at other locations on the body 2. Thus, in this embodiment, the partial region includes the circumferential region R2 and region R82.

In this embodiment, the circumferential region R2 is located relatively close to the edge of the opening 2a and continuously circumferentially around the body 2 at a position farther from the edge of the opening 2a toward the bottom 3 than any of the notches 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b. Region R82 is located between the edge of the opening 2a and the circumferential region R2 and intermittently circumferentially around the body 2 to avoid any of the notches 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b. In this embodiment, the circumferential region R2 and region R82 are regions on the opening 2a side that are bonded with adhesive, and are positioned so that when the edge of the opening 2a is virtually moved toward the bottom 3, the entire edge of the opening 2a hits somewhere in the region on the opening 2a side, and a portion of this region is positioned closer to the edge of the opening 2a than the tips of any of the notches 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b.

In the two-layer bag 1 according to the first embodiment, the band-shaped regions 1Ba, 1Bc extending along the length of the inner tubular portion of the inner layer 1B are heat-sealed to each other. However, in the two-layer bag 81 according to the present embodiment, as shown in Figures 26 to 28 and 30, adhesive 99 is instead applied to a band-shaped region R99 on the far side of the page in Figure 30, which extends along the upper edge of the inner layer 1B in Figure 30 near the upper edge, and the adhesive 99 bonds the band-shaped region R99 to a band-shaped region 1Bd on the near side of the page in Figure 30, which extends along the lower edge of the inner layer 1B in Figure 30.

In this embodiment, since heat sealing is not performed, neither the outer layer 1A nor both sides of the inner layer 1B need to have heat sealability. For example, both the outer layer 1A and the inner layer 1B may be made of kraft paper alone. However, in this embodiment, the same materials as in the first embodiment may be used for the outer layer 1A and the inner layer 1B.

In this embodiment, the outer layer 1A has incisions 91a, 92a, 93a, and 94a extending from the right side to the left side in Figure 29, on the extension lines of incisions 91b, 92b, 93b, and 94b, respectively. Furthermore, the inner layer 1B has incisions 95a, 96a, 97a, and 98a extending from the right side to the left side in Figure 30, on the extension lines of incisions 95b, 96b, 97b, and 98b, respectively. In this embodiment, as can be seen from Figures 34 to 37 described below, the corner bottom 3 can be formed using incisions 91a, 92a, 93a, 94a, 95a, 96a, 97a, and 98a.

Figure 31(a) is a schematic side view showing an example of a two-layer bag manufacturing apparatus (bag making machine) 101 used to manufacture the two-layer bag 81 shown in Figure 23, and corresponds to Figures 10(a) and 16(a). Figure 31(b) is a schematic plan view showing some elements 52, 114 of the manufacturing apparatus 101 and the appearance of the outer layer sheet 1A' and inner layer sheet 1B', and corresponds to Figures 10(b) and 16(b). In Figure 31, elements that are the same as or correspond to elements in Figures 10 and 16 are given the same reference numerals, and redundant explanations will be omitted.

The manufacturing apparatus 101 differs from the manufacturing apparatus 61 shown in Figure 16 in the following ways:

The manufacturing apparatus 101 includes a sheet supply unit 102 similar to the sheet supply unit 32 in Figures 10 and 16, a slit forming/application unit 103, a cylindrical forming unit 104, a cutting/bottom forming unit 105, and an accumulation unit 106.

As shown in FIG. 10, the incision forming and application unit 103 includes guide rollers 41, 42, 44, 45, 46, 111, 117, and 118, a rotor 112 with cutting blades that forms incisions 95a, 96a, 97a, 98a, 95b, 96b, 97b, and 98b in the inner layer sheet 1B' as shown in FIG. 33, a receiving roller 113 that receives the rotor 112 with cutting blades, an application nozzle 114 that applies adhesive 99 to region R99 of the inner layer 1B in FIG. 30, and an application nozzle 114 that applies incisions 91a, 92a, 93a, 94a, and 91b in the outer layer sheet 1A' as shown in FIG. 32. b, 92b, 93b, and 94b; a receiving roller 116 that receives the cutting blade rotor 115; an application nozzle 52 that applies adhesive 21 to region R1 of outer layer 1A in FIG. 29; a container 47 that contains adhesive to become adhesives 22, 82, and 23; a take-out roller 48 that takes the adhesive from container 47; and an application roller 49 made of rubber or the like that applies the adhesive taken out by the take-out roller 48 to regions R22, R82, and R23 of outer layer sheet 1A' that passes between the take-out roller 48 and the receiving roller 50.

Note that Figure 32 is a schematic plan view showing a portion of outer layer sheet 1A', which forms a continuation of outer layer 1A in Figure 31, and showing the locations of incisions 91a, 92a, 93a, 94a, 91b, 92b, 93b, and 94b. Figure 33 is a schematic plan view showing a portion of inner layer sheet 1B, which forms a continuation of inner layer 1B in Figure 31, and showing the locations of incisions 95a, 96a, 97a, 98a, 95b, 96b, 97b, and 98b.

As shown in Figure 31, after the cutting blade rotor 112 forms incisions 95a, 96a, 97a, 98a, 95b, 96b, 97b, and 98b in the inner layer sheet 1B', the coating nozzle 114 applies adhesive 99 to region R99 in the inner layer sheet 1B', and the inner layer sheet 1B' is then guided to the guide roller 45. After the cutting blade rotor 115 forms incisions 91a, 92a, 93a, 94a, 91b, 92b, 93b, and 94b in the outer layer sheet 1A', the coating nozzle 52 applies adhesive 24 to region R1, and the coating roller 49 applies adhesives 22, 82, and 23 to regions R2, R82, and R3 in the outer layer sheet 1A', and the outer layer sheet 1A' is then guided to the guide roller 45. The inner layer sheet 1B' and outer layer sheet 1A' are guided by the guide rollers 45, where they overlap again, exit the incision forming and coating section 103, and enter the cylindrical forming section 104.

The cylindrical molding unit 104 molds the inner layer sheet 1B' and the outer layer sheet 1A' into a cylindrical shape, folds them, and completes the bonding of each part with adhesives 21, 22, 23, 82, and 99. The cylindrical molding unit 104 has molding members that perform the molding, but these are not shown in the figure.

Once the outer layer sheet 1A' and inner layer sheet 1B' are formed into a complete cylindrical body by the cylindrical forming unit 104, this cylindrical body passes through guide rollers 54 and is cut into cylindrical bodies 81' for one two-layer bag 1 by the cutting and bottom forming unit 105. Each cylindrical body 81' for one two-layer bag 1 is folded by the cutting and bottom forming unit 105 using the incisions 91a, 92a, 93a, 94a, 95a, 96a, 97a, and 98a as shown in FIG. 34, and then adhesive is applied to region 121 as shown in FIG. 35. The bag is then folded again as shown in FIG. 36, and a bottom sheet 3a such as paper is attached as shown in FIG. 36. In this way, the two-layer bag 81 shown in FIG. 23 is completed, and the completed two-layer bag 81 is accumulated in the accumulation unit 106.

Note that Figure 34 is a schematic rear view showing the process of forming the bottom 3 of the two-layer bag 81 shown in Figure 23. Figure 35 is a schematic rear view showing the process of forming the bottom 3 of the two-layer bag 91 shown in Figure 23 after the state shown in Figure 34. Figure 36 is a schematic rear view showing the process of forming the bottom 3 of the two-layer bag 81 shown in Figure 23 after the state shown in Figure 35. Figure 37 is a schematic rear view showing the state after formation of the bottom 3 of the two-layer bag 91 shown in Figure 23 has been completed.

In the two-layer bag 81 of this embodiment, similar to the two-layer bag 1 of the first embodiment, the desired contents are placed into the body portion 2 through the opening 2a at the top of the body portion 2, and then the opening 2a is closed to complete the bag.

In the two-layer bag 81 of this embodiment, the inner tubular portion made of the inner layer 1B and the outer tubular portion made of the outer layer 1A are bonded together in the circumferential region R2 with adhesive 22, eliminating the risk of contents accidentally getting between the inner layer 1B and the outer layer 1A on the bottom 3 side. Furthermore, in the two-layer bag 81 of this embodiment, the inner tubular portion made of the inner layer 1B and the outer tubular portion made of the outer layer 1A are bonded together in the region R82 with adhesive 82, further reducing the risk of contents accidentally getting between the inner layer 1B and the outer layer 1A.

Figure 38 is a schematic perspective view of a two-layer bag 131 according to a second comparative example, which is compared to the two-layer bag 81 shown in Figure 23, with the opening moderately opened, and corresponds to Figure 1. In Figure 38, elements that are the same as or correspond to elements in Figure 23 are given the same reference numerals, and redundant explanations will be omitted.

The two-layer bag 131 shown in Figure 38 differs from the two-layer bag 81 shown in Figure 23 only in that, in the two-layer bag 81 shown in Figure 23, the inner tubular portion made of the inner layer 1B and the outer tubular portion made of the outer layer 1A are bonded together with adhesive 82 in region R82, whereas in the two-layer bag 131 shown in Figure 38, there is no bonding in region R82.

In the two-layer bag 131 shown in Figure 38, the area on the opening 2a side that bonds the inner tubular portion made of the inner layer 1B and the outer tubular portion made of the outer layer 1A is composed only of the circumferential region R2. The circumferential region R2 is positioned farther from the edge of the opening 2a toward the bottom 3 than any of the notches 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b, meaning there is a limit to how close the circumferential region R2 can be to the edge of the opening 2a. Therefore, if the area on the opening 2a side that bonds the inner tubular portion made of the inner layer 1B and the outer tubular portion made of the outer layer 1A is composed only of the circumferential region R2, as in the two-layer bag 131 shown in Figure 38, there is a high risk of contents accidentally getting between the inner layer 1B and the outer layer 1A between the circumferential region R2 and the edge of the opening 2a. However, in the two-layer bag 81 according to this embodiment, the region R82 bonded with the adhesive 82 is positioned closer to the edge of the opening 2a than the tips of any of the incisions 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b, so the risk of contents accidentally getting between the inner layer 1B and the outer layer 1A is reduced compared to the two-layer bag 81 shown in Figure 38. Moreover, in the two-layer bag 81 according to this embodiment, not only the circumferential region R2 but also the region R82 avoids the incisions 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b, so even if the incisions 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b are formed after the application of the adhesive 82, the incisions 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b are formed. There is no risk of the adhesive 22, 82 sticking to the cutting edges 112, 115 and causing problems, and even if the adhesive 22, 82 is applied after the cuts 91b, 92b, 93b, 94b, 95b, 96b, 97b, 98b are formed, there is no risk of the adhesive 22, 82 leaking from the cuts 91b, 92b, 93b, 94b, 95b, 96b, 97b, 98b to the back side of the applied surface and causing problems.

In the present invention, in the two-layer bag 81 according to this embodiment, the region R82 disposed between the circumferential region R2 and the edge of the opening 2a may be limited to a portion of that region. For example, the region R82 does not have to be disposed on both side portions 13, 14.

Furthermore, Figure 39 shows examples of patterns for the region on the opening 2a side that can be used in a two-layer bag such as this embodiment, where an adhesive is used to bond the inner tubular portion made of the inner layer 1B and the outer tubular portion made of the outer layer 1A. Figure 39 is a partially enlarged schematic front view showing examples of patterns for the region on the opening 2a side, and shows the portion of the front surface 11 on the opening 2a side.

Figure 39(a) shows the pattern of the area on the opening 2a side in this embodiment.

Figure 39(b) shows an example in which the region R82 bonded with adhesive 82 is configured as shown by the dashed line.

Figure 39 (c) shows an example in which the region R182 adhered with adhesive 182 is configured with the same thickness so as to be as close as possible to the edge of the opening 2a while avoiding the notches 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b.

Figure 39(d) shows an example in which the region R222 adhered with adhesive 222 is configured with different thicknesses so as to be as close as possible to the edge of the opening 2a while avoiding the notches 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b.

Figure 39(d) shows an example in which region R322, which is bonded with adhesive 322, is configured to close the gap in region R82, which is bonded with adhesive 82, at a position below region R322 with sufficient horizontal space.

In all of the examples shown in Figure 39, the region on the opening 2a side where the adhesive bonds the inner tubular portion made of inner layer 1B and the outer tubular portion made of outer layer 1A is positioned so as to avoid any of the incisions 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b, and the opening side region is positioned so that when the edge of opening 2a is virtually moved toward bottom 3, the entire edge of opening 2a comes into contact with somewhere in the opening side region, with a portion of the opening side region being positioned closer to the edge of opening 2a than the tip of any of the incisions 91b, 92b, 93b, 94b, 95b, 96b, 97b, and 98b.

Even when this type of opening side region is adopted, the same advantages as the two-layer bag 81 of this embodiment can be obtained.

Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

1, 81 Two-layer bag 1A Outer layer 1A' Outer layer sheet 1B Inner layer 1B' Inner layer sheet 2 Body 2a Opening 22, 82 Adhesive 25 Heat-sealed portion 91b, 92b, 93b, 94b, 95b, 96b, 97b, 98b Cuts

Claims (6)

A two-layer bag having an inner layer forming an inner bag and an outer layer forming an outer bag, the inner layer and the outer layer being bonded only in a partial region,
a cylindrical body portion having an opening at one end and a closed other end, the body portion having a double structure consisting of an inner cylindrical portion made of the inner layer and an outer cylindrical portion made of the outer layer,
band-like regions extending in the length direction of the inner tubular portion are heat-sealed to each other so that the inner layer forms the inner tubular portion;
an outer surface region of the inner cylindrical portion that continuously surrounds the inner cylindrical portion at a position close to the edge of the opening and an inner surface region of the outer cylindrical portion that continuously surrounds the outer cylindrical portion at a position close to the edge of the opening are bonded together with an adhesive so as to face each other over the entire circumference of these regions;
A two-layer bag characterized by: one surface of the inner layer has heat sealability;
the other surface of the inner layer is non-heat-sealable,
a band-shaped portion along one side of the inner layer extending in the length direction of the inner tubular portion is folded back so that the surface on the one side faces outward, and the folded state is maintained by adhesion with an adhesive,
The band-shaped portion is heat-sealed to a band-shaped region along another edge of the inner layer extending in the length direction of the inner tubular portion.
2. The two-layer bag according to claim 1. A two-layer bag according to claim 1 or 2, characterized in that it has a square bottom that closes the other end of the body. A bagged product comprising a two-layer bag according to any one of claims 1 to 3, a desired content being placed inside the inner bag, and the opening being closed. A method for producing the two-layer bag according to any one of claims 1 to 3, comprising the steps of:
applying the adhesive to a first sheet that forms a contiguous portion of the outer layer;
the first and second sheets are guided so that the adhesive applied to the first sheet does not transfer to the intended facing region of the second sheet forming the continuous inner layer, which will face the heater bar that performs the heat sealing, until the intended facing region has passed the point facing the heater bar.
A method for manufacturing a two-layer bag. A manufacturing apparatus used to manufacture the two-layer bag according to any one of claims 1 to 3,
an application unit that applies the adhesive to a first sheet that forms a continuous outer layer;
a guide section for guiding the first and second sheets so that the adhesive applied to the first sheet does not transfer to a planned facing region of the second sheet forming the continuous inner layer, which will face a heater bar that performs the heat sealing, until the planned facing region has passed a point facing the heater bar;
A manufacturing apparatus for two-layer bags, comprising: