JP7733570B2 - Composite container and method of manufacturing the composite container - Google Patents

Description

The present invention relates to a composite container and a method for manufacturing a composite container.

In recent years, efforts have been made to reduce the amount of resin used in disposable containers in order to curb the burden on the natural environment caused by plastic waste, including microplastics. Specific efforts include reducing the amount of resin used in plastic containers and replacing plastic products with paper products. Furthermore, composite containers that combine plastic containers with paper components have also been proposed.

For example, Patent Document 1 proposes a composite container that combines a resin container with a paper sleeve (reinforcing member). In this composite container, the amount of resin is reduced by providing a thin-walled section with a thickness of 0.01 mm to 0.09 mm in the body of the resin container. However, providing such a thin-walled section in the body makes the body easily deformed and difficult to grip. Therefore, this resin container is provided with a flange section connected to the body, a thick-walled section connected to the flange section in the body, and a protrusion that protrudes radially outward from the thick-walled section, with the thin-walled section positioned closer to the bottom than the thick-walled section. The body of the resin container is then inserted into a cylindrical paper sleeve, and the sleeve is supported by the protrusion. This allows for easy attachment of the resin container and the paper sleeve, and the sleeve reinforces the rigidity of the resin container, which is reduced by the thin-walled section.

Japanese Patent Application Laid-Open No. 2021-116122

According to the composite container disclosed in Patent Document 1, the amount of resin in the body is reduced by providing rigidity through the use of a paper sleeve. However, the body has a thick-walled section at the top, and the bottom is also thicker than the thin-walled section in order to maintain a certain level of strength. As a result, there is still a large amount of resin, and there is a need to further reduce the amount of resin used.

Furthermore, with the above-mentioned composite container, the resin container and paper sleeve must be prepared separately, and then the paper sleeve must be attached to the resin container. The resin container is made by blow molding a preform, and the paper sleeve is made by rolling up paperboard or the like cut into a predetermined shape including a main body and a margin, and then adhering the main body and margin with an adhesive or the like. As such, the manufacturing process for the above-mentioned conventional composite containers is complicated, and improvements in manufacturing efficiency are required.

The paper sleeves mentioned above are made of laminated paper with a functional film laminated on the surface that provides water resistance and other properties. Such composite containers contain contents containing moisture, such as food. Because the cut surfaces of the paper sleeves are not covered with the functional film, moisture may penetrate through the cut surfaces, causing the paper sleeve to become swollen. In such cases, the paper sleeve may not be able to maintain the rigidity and other properties required. Furthermore, if the cut surfaces are exposed, the laminated structure may not be maintained, for example, as the functional film on the surface may peel off from the edges, and the paper sleeve may not be able to maintain the rigidity and appearance required.

The present invention aims to provide a composite container and a manufacturing method thereof that can significantly reduce the amount of resin used and improve manufacturing efficiency while maintaining the functionality required for the storage section. It also provides a new container with a storage section in which the face piece is joined with a resin rib, and a new manufacturing method for such a container.

In order to solve the above problem, the composite container of the present invention is a composite container having a storage section formed by joining one end and the other end of a paper panel with a resin joining rib, and at least one of the one end and the other end has a recess that is recessed into the inside of the surface, and the joining rib has a predetermined width and a constant width region that joins the one end and the other end so that both sides are covered with a predetermined distance D1 between them in the part other than the recess, and a widened region that covers both sides in the recess and is widened from the predetermined width in accordance with the amount of recess in the recess, and the joining rib has a top rib that forms the outer edge of the top surface of the storage section, and the top rib has an inner frame body joined to the top end of the side paper panel that forms the side of the storage section, a flange portion that protrudes outward at the upper end of the inner frame body, and an outer frame body that hangs down from the outer edge of the flange portion, and an inner circumferential rib is provided along the lower end of the inner circumferential surface of the outer frame body .
In the composite container according to the present invention, it is preferable that a peripheral rib be provided at the lower end of the outer peripheral surface of the outer frame so as to protrude radially outward.

In the composite container of the present invention, it is preferable that the one end is the outer peripheral end of a bottom paper panel that forms the bottom surface of the storage section, the other end is the bottom end of a side paper panel that forms the side surface of the storage section, the recess is provided on the outer peripheral end of the bottom paper panel or the bottom end of the side paper panel, and the joining rib is a bottom rib that joins the outer peripheral end of the bottom paper panel and the bottom end of the side paper panel to form the outer edge of the bottom surface.

In the composite container of the present invention, the side surface of the storage section has side ribs that join one side edge and the other side edge of one or more of the side paper panels from both sides, with the two edges spaced a predetermined distance D2 apart, and it is preferable that the side ribs and the bottom rib are joined in the widened region.

In the composite container according to the present invention, the joining rib is preferably an injection-molded member formed by injecting a resin material from a position corresponding to the widened region.

In order to solve the above problems, the manufacturing method of a composite container according to the present invention is a manufacturing method of a composite container for manufacturing a composite container having a storage section configured by joining one end and the other end of a paper face piece with a joining rib made of resin, wherein at least one of the one end and the other end is provided with a recess that is recessed into the inside of the surface, and the joining rib has a predetermined width and has a constant width region that joins the one end and the other end so as to cover both sides with a predetermined distance D1 between them in the part other than the recess, and a widened width region that covers both sides in the recess and is widened from the predetermined width in accordance with the amount of recession of the recess, and the joining The rib has a top rib that forms the outer edge of the top surface of the storage section, and the top rib has an inner frame body that is joined to the top end of the side paper face body that forms the side of the storage section, a flange portion that protrudes outward at the upper end of the inner frame body, and an outer frame body that is suspended from the outer edge of the flange portion, and an inner circumferential rib is provided along the inner circumferential surface at the lower end of the inner surface of the outer frame body, and a mold is used to form a resin filling section shaped according to the joining rib, and the paper face body is placed at a predetermined position in the mold with the one end and the other end separated by a predetermined distance D1, and a position corresponding to the widened region of the resin filling section is used as a gate section, and resin material is filled into the resin filling section from the gate section.

In the composite container of the present invention, the storage section is composed of a paper face piece and a resin joining rib, which allows for a significant reduction in the amount of resin used compared to when the entire storage section is made of resin. The joining rib also joins one end of the paper face piece to the other end, covering both sides. Therefore, even when the composite container is used as a container for storing contents containing moisture, such as food, or liquid, it is possible to prevent moisture from penetrating the inside of the paper face piece through the joint between the one end and the other end, which could cause problems such as a decrease in the rigidity of the paper face piece.

Furthermore, when manufacturing the composite container according to the present invention, for example, injection molding (insert molding) can be applied. That is, the paper face piece is placed in a predetermined position in a mold, and one end and the other end to be joined are inserted into the resin-filled portion of the mold. Then, by filling the mold with resin material, the two ends can be joined together while covering both sides of the ends, forming a single unit.

In this case, by providing a widened region in the joining rib and a recess in the paper face piece, as in the composite container of the present invention, and by designing the position of the mold corresponding to this widened region as the gate section, it becomes easy to design the gate diameter so that the resin material can be injected smoothly into the resin filling section, even when the constant width region is narrow. Furthermore, by applying the composite container manufacturing method of the present invention, by positioning one end and the other end of the paper face piece at a position at least a predetermined distance D3 away from the gate section, it is possible to prevent the filling pressure of the resin material from being directly applied to these ends, thereby preventing problems such as bending of these ends during molding. Therefore, the composite container manufacturing method of the present invention allows for the production of composite containers made of different materials with high yields using a method similar to conventional injection molding (insert molding).

As described above, the composite container and manufacturing method for a composite container according to the present invention can reduce the amount of resin used and improve manufacturing efficiency, while maintaining the functionality required for the storage section. It also provides a new container and a new manufacturing method for a container that has a storage section in which the face piece is joined with a resin rib.

1A and 1B are diagrams showing a composite container according to an embodiment of the present invention, in which (a) is a top view and (b) is a front view, part of which shows a cross section taken along line BB in FIG. 1A (and FIG. 3A). 2A and 2B are plan views showing the paper face pieces that make up the storage section of the composite container shown in FIG. 1, where (a) shows the bottom paper face piece that makes up the bottom surface of the storage section, and (b) shows the side paper face piece that makes up the side surface of the storage section. 2A and 2B are diagrams for explaining the composite container shown in FIG. 1, in which (a) is a cross-sectional view taken along line AA in FIG. 1, and (b) is a bottom view of the composite container. 2 is a diagram for explaining the constant width region A- _N and the widened width region A- _W , etc., according to the present invention, and is a diagram showing a part of the bottom surface of the composite container shown in FIG. 1. FIG. 1A is a cross-sectional view taken along CC in FIG. 3A, and FIG. 3B is a cross-sectional view taken along DD in FIG. 3A. 2A and 2B are schematic diagrams for explaining a method for manufacturing the composite container shown in FIG. 1, in which (a) shows the state before the resin material is filled into the mold, and (b) shows the state when the resin material is filled into the mold. 1A and 1B are diagrams showing a composite container as a comparative example of the present invention, in which (a) is a side view thereof, part of which shows a cross section at the same position as in FIG. 1B, and (b) is a top view thereof. FIG. 7 is a diagram showing a part of the bottom surface of the composite container shown in FIG. 6 as a comparative example. 10A and 10B are schematic diagrams for explaining a manufacturing method of a composite container of a comparative example.

The following describes a composite container and a method for manufacturing a composite container according to an embodiment of the present invention, with reference to the drawings.

1. Composite Container First, the schematic configuration of a composite container 100 of this embodiment will be described with reference to Figures 1 to 3. As shown in Figure 1(b), the composite container 100 has a bottom surface 11 and side surfaces 12, and a storage section 10 with an open top surface 13. The storage section 10 is configured into a bottomed, cylindrical cup-like shape by joining the ends of the paper panels (bottom paper panel 31, side paper panel 32) to be joined (the outer peripheral edge 31a of the bottom paper panel 31 and the bottom edge 32c of the side paper panel 32, and one side edge 32a and the other side edge 32b of the side paper panel 32 (see also Figures 2(a) and 2(b))) with joining ribs 20 so as to cover both sides. In this way, the composite container 100 is configured as a hybrid container made of different materials, namely, a resin material and a paper material.

As shown in Figures 1(a) and 3(b), the bottom surface 11 and the top surface 13 each have a coaxial circular shape, and as shown in Figures 1(a) and 1(b), the top surface 13 has a larger diameter than the bottom surface 11. Hereinafter, the line passing through the centers of the bottom surface 11 and the top surface 13 will be referred to as the central axis O, the direction along the central axis O will be referred to as the axial direction, the direction perpendicular to the central axis O will be referred to as the radial direction, and the direction circumferentially around the central axis O will be referred to as the circumferential direction. Furthermore, the vertical direction refers to the axial direction. Furthermore, when the composite container 100 is placed in the state shown in Figure 1, the bottom surface 11 side will be referred to as the "lower" side, and the top surface 13 side will be referred to as the "upper" side in the axial direction. Note that Figure 1(b) shows a cross-sectional view to the right of the central axis O.

First, the paper face piece will be described. The bottom surface 11 of the storage unit 10 includes a bottom paper face piece 31 shown in Figure 2(a), and the side surface 12 includes a side paper face piece 32 shown in Figure 2(b). As shown in Figure 2(a), the bottom paper face piece 31 has a roughly circular shape that matches the shape of the bottom surface 11, and a recess 31b is provided at the outer peripheral edge 31a, which is recessed into the inside of the face. Figure 2(a) shows an example of the recess 31b having a roughly semicircular shape cut out from the outer peripheral edge 31a of the bottom paper face piece 31, but the recess 31b may also have a roughly V-shaped cutout or a roughly rectangular cutout shape cut out into the inside of the face at the outer peripheral edge 31a, and the shape of the recess 31b is not particularly limited.

On the other hand, the side paper face piece 32 has a roughly fan-shaped configuration as shown in Figure 2(b). As shown in Figure 3(a), one side end 32a and the other side end 32b of the side paper face piece 32 are joined by the side rib 22, resulting in a cylindrical shape as shown in Figure 1(b).

Next, the joining rib 20 will be described. In this embodiment, the joining rib 20 is joined to at least one of the bottom paper panel 31 and the side paper panel 32, and has a bottom rib 21, a side rib 22, a top rib 23, and a reinforcing rib 24, as shown in Figure 1(b). The joining rib referred to in this invention mainly corresponds to the bottom rib 21 in the composite container 100 of this embodiment.

As shown in Figures 1(a) and (b), the bottom rib 21 forms the outer edge of the bottom surface 11 of the storage section 10 and joins the outer peripheral edge 31a of the bottom paper panel 31 and the bottom edge 32c of the side paper panel 32. As shown in Figure 1(b), the bottom rib 21 has a bottom annular frame 21a located on the bottom surface 11 side, covering both sides of the outer peripheral edge 31a of the bottom paper panel 31, and a side annular frame 21b located on the side surface 12 side, covering both sides of the bottom edge 32c of the side paper panel 32. The bottom annular frame 21a and the side annular frame 21b are connected together by connecting portions 21c, and are configured as a ring-shaped frame with a generally L-shaped cross section as a whole.

Next, the bottom rib 21 will be further described with reference to FIG. 4. FIG. 4 is a bottom view showing a portion of the bottom surface 11 of the storage section 10. In FIG. 4, the outer peripheral edge 31a of the bottom paper panel 31 and the bottom edge 32c of the side paper panel 32 are indicated by dashed lines. As shown in FIG. 4, the bottom rib 21 has a constant width region A _N having a predetermined width Wn along the outer edge of the bottom surface 11, and a widened width region A _W having a widened width at a position corresponding to the recess 31b provided in the bottom paper panel 31. In the bottom rib 21, the constant width region A _N extends from near one side edge 32a of the side paper panel 32 to the other side edge 32b. In the constant width region A _N , the outer peripheral edge 31a of the bottom paper panel 31 and the bottom edge 32c of the side paper panel 32 are covered and joined together with a predetermined distance D1 between them.

The widened region _A1W is connected to the constant width region _A1N , and the widened region _A1W and the constant width region _A1N are integrated. The widened region _A1W is an area wider than the constant width region _A1N depending on the amount of recession of the recess 31b into the surface. The widened region _A1W covers both sides of the recess 31b. In the widened region _A1W , the outer peripheral edge 31a of the recess 31b and the bottom edge 32c (one side edge 32a or the other side edge 32b) of the side paper panel 32 are spaced apart by more than the above-mentioned predetermined distance D1.

In Fig. 4, the roughly circular shape in the widened region A _W is a gate mark 40 that is created when the joining rib 20 is manufactured by injection molding (insert molding). In an injection-molded product, a mark 40 remains as a gate mark from a gate portion 54 (see Fig. 6) used to inject a resin material into a mold 50 during injection molding. The gate mark 40 is also shown in Fig. 3(b). However, although the gate mark 40 is shown by a solid line in Figs. 3(b) and 4, the gate mark 40 in an actual composite container 100 or in a composite container according to the present invention does not necessarily have to be circular, and may have another shape such as a square, and does not necessarily have to be clearly visible.

As shown in Figure 4, in the composite container 100 of this embodiment, the outer peripheral edge 31a of the bottom paper panel 31 and the bottom edge 32c of the side paper panel 32 are not positioned inside the gate mark 40 when viewed from the bottom, and each edge (31a, 32c) of these paper panels (31, 32) is positioned outside the outer edge of the gate mark 40. In this embodiment, each edge (31a, 32c) of the paper panels (31, 32) is positioned at a distance of at least a predetermined distance D3. However, D4 in Figure 4 indicates the distance between the gate mark 40 and the other side edge 32b of the side paper panel 32, and the distance between the gate mark 40 and one side edge 32a of the side paper panel 32 is also the same distance as D4, showing an example where D4 ≥ D3. However, the separation distance D4 may be less than the above-mentioned predetermined distance D3, and although there are no particular limitations on the relationship with the predetermined distance D3, it is preferable to set D4≧D3 as shown in Figure 4. However, if the separation distance D4 is too large, the amount of resin required for the side rib 22 will increase, so the separation distance D4 is preferably in the range of 0.1 mm to 2.5 mm, and more preferably in the range of 0.5 mm to 2.0 mm.

As shown in Figures 1(b) and 5(a), one end of the side rib 22 is connected to the bottom rib 21 and the other end is connected to the top rib 23. Note that Figure 5(a) is a cross-sectional view taken along the line C-C in Figure 3(a). As shown in Figure 3(a), one side end 32a and the other side end 32b of the side paper face piece 32 are joined by the side rib 22, spaced apart by a predetermined distance D2 as shown in Figure 4. Furthermore, both sides of the one side end 32a and the other side end 32b of the side paper face piece 32 are covered by the side rib 22. Furthermore, as shown in Figures 1(b) and 5(a), the side rib 22 is joined to the widened region A- _W of the bottom rib 21 and integrated with it. Furthermore, when viewed from the bottom, the side rib 22 is positioned outside the gate mark 40.

As shown in Figure 3(a) and other figures, a reinforcing rib 24 is provided on the side surface 12 of the storage section 10 at a position opposite the side rib 22 across the central axis O. In the example shown in Figure 3(a) and other figures, the reinforcing rib 24 is joined by being adhered to the outer surface of the side paper face piece 32, and like the side rib 22, one end is connected to the bottom rib 21 and the other end is connected to the top rib 23. However, the reinforcing rib 24 may also be adhered to the inner surface of the side paper face piece 32 instead of the outer surface of the side paper face piece 32.

In the example shown in Figure 3(a) and other figures, the side ribs 22 and reinforcing ribs 24 protrude radially outward from the outer surface of the side paper face piece 32, forming convex ribs extending from the bottom rib 21 to the top rib 23. As shown in Figure 3(a) and other figures, the side ribs 22 also protrude radially inward. However, this is not limited to the illustrated example, and the side ribs 22 may be arranged to protrude only radially outward from the outer surface of the side paper face piece 32, or may be arranged to protrude only radially inward from the inner surface. The reinforcing ribs 24 are also not limited to the illustrated example, and may be arranged on the inner surface of the side paper face piece 32 and protrude radially inward from the inner surface, or may be arranged on both sides of the side paper face piece 32. In the example shown in Figure 3(a) and other figures, the reinforcing ribs 24 may be replaced with side ribs 22, and the storage section 10 may be constructed by joining two side paper face pieces 32. In this case, as shown in Figure 3(a), the side ribs 22 may be used on both the outer and inner sides of the side paper panel 32, protruding radially inward and outward, or may protrude on only one side.

As shown in Figures 3(a) and 5(a) and (b), the side surface 12 of the storage section 10 is composed only of the side paper panel 32, except for the locations where the side ribs 22 and reinforcing ribs 24 are provided.

By joining the side ribs 22 as described above when forming the paper side panel 32 into a cylindrical shape, the side ribs 22 function not only as joining members but also as reinforcing members to supplement the strength (rigidity) of the storage section 10. Furthermore, by providing reinforcing ribs 24, as in this embodiment, the strength of the storage section 10 can be further improved. The reinforcing ribs 24 are joined (adhered) to the outer surface of the paper side panel 32 at a position approximately midway between one side end 32a and the other side end 32b of the paper side panel 32.

The top surface ribs 23 form the outer edge of the top surface 13 of the storage section 10. As shown in Figures 1(a), (b), and 3(b), the top surface ribs 23 comprise an inner frame body 23a joined to the top end 32d of the side paper panel 32, a flange portion 23b protruding outward from the upper end of the inner frame body 23a, and an outer frame body 23c suspended from the outer edge of the flange portion 23b. The inner frame body 23a and the outer frame body 23c each have a predetermined length in the axial direction and are configured as ring frames with a thin radial thickness. In other words, the top surface ribs 23 have a roughly U-shaped cross section that opens downward, formed by the inner frame body 23a, flange portion 23b, and outer frame body 23c. In the composite container 100 of this embodiment, the top rib 23 is configured to have a roughly U-shaped cross section, which allows the thickness of the inner frame 23a, flange portion 23b, and outer frame 23c to be thin, making it easier to maintain the required strength even when the amount of resin is reduced.

In addition, in this embodiment, as shown in Figures 1(b) and 3(b), four inner peripheral ribs 23d are provided at equal circumferential intervals along the inner peripheral surface at the lower end of the inner peripheral surface of the outer frame body 23c. The inner peripheral ribs 23d protrude radially inward from the inner peripheral surface of the outer frame body 23c and have a predetermined width in the circumferential direction. By providing the inner peripheral ribs 23d on the inner peripheral surface of the outer frame body 23c, the strength of the top rib 23 can be increased. Furthermore, when the composite container 100 is used as a refill container, the inner peripheral ribs 23d can be used to fit into undercuts provided at the joint location. Furthermore, an outer peripheral rib 23e is provided around the entire lower end of the outer peripheral surface of the outer frame body 23c so as to protrude radially outward. By providing these inner peripheral ribs 23d and outer peripheral ribs 23e, the strength required for the top surface 13 of the storage unit 10 can be better maintained even when the thicknesses of the inner frame body 23a, flange portion 23b, and outer frame body 23c are reduced.

Furthermore, in this embodiment, as shown in Figures 1(a) and 1(b), an annular convex rib 23f that protrudes axially upward is provided on the top surface 13 of the flange portion 23b. The annular convex rib 23f is used as a contact ring for the packing seal.

Next, the constituent materials of the composite container 100 will be described. In the composite container 100, the type of resin constituting the joining rib 20 is not particularly limited, but a wide range of general-purpose resins used as packaging container materials can be used, such as polypropylene (homopolymer, block copolymer, random copolymer), polyethylene (high-density polyethylene, low-density polyethylene, etc.), and polyethylene terephthalate resin. In particular, when employing the manufacturing method described below, it is more preferable to use an olefin-based resin such as polypropylene or polyethylene as the constituent material of the joining rib 20.

The paper face pieces (31, 32) that make up the storage section 10 may be formed thin and flat by agglutinating plant fibers or other fibers. They may be laminated or composite paper made by laminating multiple sheets of synthetic paper, gravure paper, or various plastics, or functional paper that has been given properties such as water resistance or oil resistance. The basis weight of the paper used can be designed as appropriate. In particular, when using the manufacturing method described below, it is more preferable to use laminated paper that has been given properties such as water resistance or oil resistance by laminating an olefin resin sheet such as polyethylene resin or a polyethylene terephthalate resin sheet on the surface.

In this invention, the container 10 is constructed primarily by joining paper face pieces (31, 32) with joining ribs 20 to reduce the amount of resin. However, the paper face pieces (31, 32) can also be replaced with resin face pieces, such as the packaging film for each main container. In this case, the amount of resin can be reduced by replacing most of the bottom surface 11 and side surfaces 12 of the container 10 with thin resin films. In this case, a multilayer film can be used in which a barrier layer (such as an EVOH layer) is used as an intermediate layer, and an olefin resin sheet such as a polyethylene resin or a polyethylene terephthalate resin sheet is laminated on the inner and outer surfaces of the barrier layer. This can also be manufactured using a method similar to the composite container manufacturing method described below. Furthermore, since barrier layers generally contain hydrophilic groups such as OH groups, contact with moisture (including water vapor) is undesirable. In this case, covering the end surfaces with joining ribs 20 as described above can prevent contact between the barrier layer and moisture.

2. Manufacturing Method of Composite Container Next, a method for manufacturing the composite container 100 will be described. When manufacturing the composite container 100, injection molding can be used, and so-called insert molding can also be applied. A mold 50 (see FIG. 6(a)) having a resin-filled portion 51 corresponding to the shape of the joining rib 20 and a clamping portion 52 for clamping the paper face pieces (31, 32) is prepared, along with the bottom paper face piece 31 and the side paper face piece 32 (see FIG. 2) that have been pre-cut to a predetermined shape. The bottom paper face piece 31 is provided with the recess 31b. The mold 50 is configured to be separable as appropriate, and the clamping portion 52 may be formed using a dividing surface other than the resin-filled portion 51 of the mold 50.

6(a) shows a side cross section of the mold 50, which corresponds to the B-B cross section in FIG. 3(a). The mold 50 is provided with a runner 53 for injecting molten resin material into the resin filling portion 51, and a gate 54 which serves as an inlet for the resin material from the runner 53 to the resin filling portion 51. In this embodiment, the runner 53 and the gate 54 are provided at a position corresponding to the widened region A _W of the bottom rib 21. The runner 53 is connected to an injection molding machine (not shown) and a distribution path for the resin material via a spool (also not shown).

The bottom paper face piece 31 and side paper face piece 32 are placed in predetermined positions within the mold 50 as inserts, and are clamped by the clamping section 52. Figures 6(a) and (b) show the bottom paper face piece 31 placed in a predetermined position within the mold 50. As shown in Figure 6(a), the outer peripheral end 31a of the bottom paper face piece 31 is inserted to a predetermined insertion depth into the resin-filled section 51. At this time, the outer peripheral end 31a of the bottom paper face piece 31 is positioned axially at approximately the center of the thickness direction of the resin-filled section 51, and is positioned so that the distance from the gate section 54 is the same as the predetermined distance D3 shown in Figure 4.

Although not shown, each end of the side paper face piece 32 (bottom end piece 32c, one side end piece 32a, the other side end piece 32b, and top end piece 32d) is also inserted to a predetermined insertion depth into the resin-filled section 51. At this time, in the region corresponding to the constant width region A- _N of the bottom rib 21, the outer peripheral edge piece 31a of the bottom paper face piece 31 and the bottom end piece 32c of the side paper face piece 32 are positioned so as to be spaced apart by the predetermined distance D1 shown in Figure 4. Similarly, in the resin-filled section 51, one side end piece 32a and the other side end piece 32b of the side paper face piece 32 are positioned so as to be spaced apart by the predetermined distance D2 shown in Figure 4, and the top end piece 32d of the side paper face piece 32 is also positioned so as to be inserted to a predetermined insertion depth.

After each paper face piece (31, 32) is placed in a predetermined position relative to the mold 50, molten resin material is injected from the injection molding machine. The resin material passes through the runner section 53 and flows into the resin-filled section 51 from the gate section 54, as shown by the arrows in FIG. 6(b). The resin material that flows into the resin-filled section 51 flows toward the area for molding the bottom rib 21 and the area for molding the side rib 22, and then toward the area for molding the reinforcing rib 24 and the area for molding the top rib 23. During this process, the resin material flows around both sides of each end (31a, 32a-32d) of the paper face pieces (31, 32), filling each area within the resin-filled section 51. As a result, both sides of each end (31a, 32a-32d) of each paper face piece (31, 32) are covered with resin material, and the joining rib 20 is molded into a predetermined shape. Then, the molded product is removed from the mold 50, and the gate portion 54 is cut off, thereby obtaining the composite container 100 having the storage portion 10 that has a bottomed cylindrical shape in which both surfaces of each end (31a, 32a-32d) of each paper face piece (31, 32) are covered with the joining rib 20 and joined to the joining rib 20. When the gate portion 54 is cut off, the gate mark 40 remains in the widened region A _W in the bottom annular frame 21a of the bottom rib 21.

Here, the above-mentioned predetermined width Wn and each of the predetermined distances D1, D2, D3, and D4 can be appropriately set based on the size of the composite container 100, the strength required for the storage section 10, the type and thickness of the paper face pieces (31, 32), the type and physical properties such as viscosity of the resin material constituting the joining rib 20, etc.

For example, the predetermined distance D1 is required to be a distance that ensures sufficient bonding strength between the outer peripheral edge 31a of the bottom paper panel 31 and the bottom edge 32c of the side paper panel 32 and sufficient resin to completely cover both end faces. The same applies to the predetermined width Wn and predetermined distance D2. In this case, even if the two can be bonded sufficiently, theoretically, if it is difficult to get enough resin material to flow between the outer peripheral edge 31a of the bottom paper panel 31 and the bottom edge 32c of the side paper panel 32 within the mold 50, the composite container 100 cannot be manufactured with a high yield. Therefore, it is preferable to appropriately determine the width of the widened region _AW and the depth of the recess 31b, taking these factors into consideration.

On the other hand, it is preferable to set the predetermined distance D3 to a distance that prevents each end (31a, 32c) inserted into the resin filling section 51 from being bent due to the influence of the filling pressure when the resin material is poured into the resin filling section 51 from the gate section 54.
The separation distance D4 is preferably set to, for example, the predetermined distance D3 or more, but may be set to an appropriate value as appropriate, and may be set to a value less than the predetermined distance D3 as described above.

Here, a polyolefin resin such as polypropylene or polyethylene terephthalate resin is used as the filler resin material filled into the mold 50, and the bottom paper face piece 31 and the side paper face pieces 32 are made of laminated paper with a polyolefin resin sheet such as a polyethylene layer or a polyethylene terephthalate resin sheet laminated on at least the surface that will be joined to the joining rib 20. By doing so, the joining rib 20 and each paper face piece (31, 32) are thermally fused together during molding, allowing the joining rib 20 to be satisfactorily joined to each paper face piece (31, 32) without the need for adhesives or the like.

In the composite container 100 described above, the bottom surface 11 and most of the side surfaces 12 of the storage section 10 are formed from paper panels (31, 32), and the outer peripheral edge 31a of the bottom paper panel 31 is joined to the bottom edge 32c of the bottom paper panel 31, and one side edge 32a of the side paper panel 32 is joined to the other side edge 32b of the side paper panel 32 by a resin bottom rib 21 or side rib 22, respectively, to form a bottomed cylindrical shape. Therefore, compared to when the entire storage section 10 is made of resin, the composite container 100 uses a significantly reduced amount of resin, while the joining ribs 20 allow the storage section 10 to maintain the strength required by the joining ribs 20.

In addition, in this embodiment, each end (31a, 32a-32d) of each paper face piece (31, 32) cut to a predetermined shape is joined with a joining rib 20. If moisture or other substances adhere to the cut end surfaces, moisture may penetrate into the interior of each paper face piece (31, 32), reducing the rigidity of each paper face piece (31, 32). If the paper face piece is made of laminated paper, this may result in problems such as the laminated sheets peeling off from the surface. However, as in the above embodiment, by joining each end (31a, 32a-32d) of the paper face piece (31, 32) so that both sides are covered with the joining rib 20, it is possible to prevent moisture from penetrating into the interior of the paper face piece (31, 32) through each end (31a, 32a-32d). Therefore, the composite container 100 can also be used suitably as a container for storing moist contents such as food or liquids. Furthermore, the joining rib 20 is joined so as to cover each end (31a, 32a-32d) of each paper face piece (31, 32) from both sides, ensuring good joining strength between the joining rib 20 and each paper face piece (31, 32).

Furthermore, the composite container 100 can be manufactured using the insert molding method described above. That is, the bottom paper panel 31 and side paper panel 32, cut to a predetermined shape, are placed in predetermined positions as inserts in the mold 50 used to manufacture the joining rib 20, and resin is then filled into the resin filling section 51 of the mold 50 through the gate section 54, thereby manufacturing the composite container 100 having the storage section 10 in which the resin joining rib 20 and the paper panel (31, 32) are joined together and integrated.

7(a), (b), and 8 show a comparative composite container 200 for comparison with the composite container 100 of the above-described embodiment. The composite container 200 has substantially the same configuration as the composite container 100 of the above-described embodiment, except that the bottom paper panel 201 does not have the recess 31b and the bottom rib 202 does not have the widened region _AW . In the comparative composite container 200, the same reference numerals as those in the composite container 100 of the above-described embodiment indicate substantially the same configuration, and therefore their description will be omitted here. Also, only some of the reference numerals are shown in FIGS. 7(a) and 7(b). Reference numeral 203 in FIGS. 7(b) and 8 indicates a gate mark, reference numeral 201b in FIG. 8 indicates a side annular frame, which has the same configuration and function as the side annular frame 21b of the composite container 100 of the above-described embodiment, and reference numeral 201c indicates a connecting portion, which has the same configuration and function as the connecting portion 21c of the composite container 100 of the above-described embodiment.

In the composite container 200 of this comparative example, as shown in Figures 7(b) and 8, the bottom rib 202 does not have an expanded width region A _1W , and therefore the bottom annular frame 202a of the bottom rib 202 is provided with only the constant width region A _1N as referred to in the composite container 100 of the above embodiment. Also, the gate portion 213 (see Figure 9) in the mold 210 is provided in this constant width region A _1N . Note that, because gate marks remain on injection-molded products, it is common to position the gate portion in a location on the molded product where they are difficult to see, and the gate portion is generally provided on the bottom side of the container.

In the composite container 200 of this comparative example, as shown in Figure 8(b), the outer peripheral edge 201a of the bottom paper panel 201 is positioned axially below the gate mark 203 on the bottom rib 202. Therefore, when the mold 210 shown in Figure 9(a) is used and resin material is filled into the resin filling section 211 from an injection molding machine via the runner section 212 and gate section 213 in the same manner as in the above embodiment, the filling pressure is directly applied to the outer peripheral edge 201a of the bottom paper panel 201. Therefore, as shown in Figure 9(b), there is a risk that the outer peripheral edge 201a of the bottom paper panel 201 will bend.

On the other hand, as in the composite container 100 of the above embodiment, by providing an expanded width region A _W in the bottom rib 21 and a recess 31 b in the bottom paper panel 31, and by defining a gate section 54 at _a position on the mold 50 corresponding to the expanded width region A W, it becomes easy to ensure the gate diameter of the gate section 54 while narrowing the constant width region A _N to reduce the amount of resin used. Furthermore, when designing the composite container 100 (and mold 50), it becomes easy to position each end (31 a, 32 a to 32 d) of each paper panel (31, 32) so that they are not positioned axially below the gate section 54. This makes it easy to design the gate diameter to achieve a flow rate and volume that will allow the resin material to be injected satisfactorily throughout the resin filling section 51. Furthermore, if the ends (31a (32a, 32b)) of the paper face pieces (31, 32) to be joined are positioned at a distance of at least the above-mentioned predetermined distance D3 from the gate portion 54, the filling pressure of the resin material is prevented from being directly applied to these ends, and problems such as bending of these ends during molding can be prevented. Therefore, according to the manufacturing method of the composite container of the present invention, the composite container made of different materials in which the paper face pieces (31, 32) and the joining rib 20 are joined can be manufactured with good yield using a method substantially similar to a normal injection molding method (insert molding method).

As described above, the composite container 100 and manufacturing method for the composite container 100 of the above embodiment can be used to form the storage section 10 by combining the resin joining rib 20 with the paper storage section 10, while reducing the amount of resin used and improving manufacturing efficiency, and maintaining the functionality required of the storage section 10.

The composite container 100 and the method for manufacturing the composite container 100 in the above embodiment are merely one aspect of the composite container and the method for manufacturing the composite container according to the present invention. The present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the present invention.

For example, in the above embodiment, a recess 31b is provided in the outer peripheral edge 31a of the bottom paper panel 31, and a widened region _AW is provided in the bottom annular frame 21a of the bottom rib 21. However, in the composite container of the present invention, it is sufficient if at least one of the one end and the other end to be joined has a recess that is recessed inwardly of the surface, due to a constant width region _{AN where} the one end and the other end to be joined are joined with a predetermined distance D1 between them, and a widened region _AW that is wider than the constant width region AN. Therefore, in the composite container 100 of the above embodiment, for example, the widened region _AW may be provided in the side annular frame 21b instead of the bottom annular frame 21a.

Alternatively, instead of the bottom rib 21, a widened region _AW may be provided in the side rib 22. In this case, for example, a constant-width region _AN may be formed by joining one side end 32a and the other side end 32b at a predetermined distance D1, with a portion of the constant-width region _AN being wider than the constant-width region _AN , and a recess may be formed in at least one of the side end 32a and the other side end 32b, with the widened region _AW covering both sides of the recess. As described above, when manufacturing the composite container 100, it is preferable to form a gate portion at a position corresponding to the widened region _AW , since this allows for a sufficient gate diameter while narrowing the width of the constant-width region _AN , thereby reducing the amount of resin used. Depending on the use of the composite container 100, it may be preferable to position the gate portion 54 on the side 12 (e.g., the back) rather than the bottom 11. Therefore, depending on the use mode and shape of the composite container 100, the positions of the recesses 31b provided in the paper face pieces (31, 32) and the widened regions _AW of the joining ribs 20 are not particularly limited.

In addition, in the above embodiment, the joining ribs 20 (bottom ribs 21, side ribs 22, top ribs 23) excluding the reinforcing ribs 24 cover both sides of each paper panel (bottom paper panel 31, side paper panel 32) and are joined to their respective ends (outer peripheral end 31a, bottom end 32c, one side end 32a, the other side end 32b, top end 32d), so that these joining ribs 20 protrude from the inner and outer sides of the storage section 10. However, depending on the contents and usage of the composite container 100, for example, each end may be bent toward the inner or outer side of the storage section 10 so that the joining ribs 20 protrude only from the inner or outer side of the storage section 10.

For example, if the contents are liquid or food with a high moisture content, it may be preferable for these joining ribs 20 not to protrude from the inner surface of the storage section 10. Furthermore, if the composite container 100 is used as a container in a bathroom, etc., water droplets may adhere to the outer surface of the composite container 100 due to condensation, etc., and it may be preferable for the joining ribs 20 not to protrude from the outer surface of the storage section 10. As described above, the manner in which the joining ribs 20 are provided can be determined arbitrarily depending on the contents and usage of the composite container 100. It is sufficient that the ends (31a, 32c, etc.) of each paper face piece (31, 32) are covered on both sides by the joining ribs 20, and if the ends (31a, 32c, etc.) of each paper face piece (31, 32) have cut end surfaces, the entire cut end surfaces are covered by the joining ribs 20. The joining ribs 20 referred to in this invention primarily refer to the bottom ribs 21 or side ribs 22, while the top ribs 23 and reinforcing ribs 24 are optional components in this invention.

In the above embodiment, side ribs 22 and reinforcing ribs 24 are provided on the side surface 12 of the storage section 10, but the number of reinforcing ribs 24 that make up the side ribs 22 can be increased or decreased depending on the strength (rigidity) required of the storage section 10. If the strength required of the storage section 10 is ensured by the side ribs 22, etc., there is no need to provide reinforcing ribs 24.

In the above embodiment, an example was shown in which the storage section 10 is formed in a cup shape with a circular bottom surface 11 and top surface 13, but the specific shape of the storage section 10 is not particularly limited. For example, it may be formed in a deep dish shape or a bottle shape, and the shapes of the bottom surface 11 and top surface 13 are not limited to circles but may be square, rectangular, polygonal, etc.

In the above embodiment, the side 12 of the storage unit 10 was formed by rolling one paper side panel 32 and joining one side end 32a and the other side end 32b with a side rib 22, but the number of paper side panels 32 used to form the side 12 of the storage unit 10 is not particularly limited. For example, two or more paper side panels 32 may be used and the ends of each paper side panel 32 may be joined together to form a cylindrical shape. Furthermore, one paper side panel 32 may have a cut portion, and the cut edges may be joined together using a portion of the side rib 22, as in the above embodiment. In this way, storage units 10 of a variety of shapes can be formed.

10: Storage section 11: Bottom surface 12: Side surface 13: Top surface 20: Joint rib 21: Bottom rib 21a: Bottom annular frame 21b: Side annular frame 21c: Connecting section 22: Side rib 23: Top rib 23a: Inner frame body 23b: Flange section 23c: Outer frame body 23d: Inner peripheral rib 23e: Peripheral rib 23f: Annular convex rib 24: Reinforcing rib 31: Bottom paper face body 31a: Peripheral edge 31b: Recess 32: Side paper face body 32a: Side edge 32b: Side edge 32c: Bottom edge 32d: Top edge 40: Gate mark 50: Mold 51: Resin filling section 52: Clamping section 53: Runner section 54: Gate section 100: Composite container 200: Composite container 201 : Bottom paper face piece 201a: Outer peripheral edge 202: Bottom rib 202a: Bottom annular frame 210: Mold 211: Resin filling portion 213: Gate portion A _N : Constant width region A _W : Widening region O: Central axis

Claims (6)

A composite container having a storage section formed by joining one end and the other end of a paper face piece with a resin joining rib,
At least one of the one end and the other end is provided with a recess recessed inward of a surface,
The joining rib has a constant width region having a predetermined width and joining the one end and the other end so that both surfaces are covered with a state in which the one end and the other end are separated by a predetermined distance D1 in a portion other than the recess, and a widened width region that covers both surfaces of the recess and is widened from the predetermined width in accordance with the recess amount of the recess,
The joining rib has a top surface rib that forms an outer edge of the top surface of the storage section,
The top rib has an inner frame body joined to the top end of the side paper body that constitutes the side of the storage section, a flange portion that protrudes outward at the upper end of the inner frame body, and an outer frame body that hangs down from the outer edge of the flange portion,
The composite container has an inner peripheral rib provided along the inner peripheral surface of the outer frame at a lower end of the inner peripheral surface . A peripheral rib is provided at a lower end of the outer peripheral surface of the outer frame so as to protrude radially outward.
The composite container according to claim 1 . The one end is an outer peripheral end of a bottom paper surface body that constitutes the bottom surface of the storage section,
The other end is a bottom end of a paper side surface that constitutes a side surface of the storage section,
The recess is provided on the outer peripheral edge of the bottom paper face piece or the bottom edge of the side paper face piece,
2. The composite container according to claim 1, wherein the joining rib is a bottom rib that joins the outer peripheral edge of the bottom paper panel and the bottom end of the side paper panel to form the outer edge of the bottom surface. The side surface of the storage section has a side rib that joins one side end and the other side end of one or more of the side paper face bodies from both sides, with the one side end and the other side end being spaced apart by a predetermined distance D2,
4. The composite container according to claim 3 , wherein the side ribs and the bottom rib are joined at the widened region. 5. The composite container according to claim 3 , wherein the joining rib is an injection-molded member formed by injecting a resin material from a position corresponding to the widened region. A method for manufacturing a composite container having a storage section formed by joining one end and the other end of a paper face piece with a resin joining rib,
a recessed portion recessed inwardly of a surface of at least one of the one end portion and the other end portion;
The joining rib has a predetermined width and includes a constant width region that joins the one end and the other end so as to cover both surfaces of the one end and the other end in a state where the two ends are spaced apart by a predetermined distance D1 in a portion other than the recess, and an expanded width region that covers both surfaces of the recess and is expanded from the predetermined width in accordance with the recess amount of the recess,
The joining rib has a top surface rib that forms an outer edge of the top surface of the storage section,
The top rib has an inner frame body joined to the top end of the side paper body that constitutes the side of the storage section, a flange portion that protrudes outward at the upper end of the inner frame body, and an outer frame body that hangs down from the outer edge of the flange portion,
an inner peripheral rib is provided along a lower end of an inner peripheral surface of the outer frame body,
A mold is used to form a resin filling portion having a shape corresponding to the joining rib,
A method for manufacturing a composite container, in which the paper face piece is placed at a predetermined position in the mold with the one end and the other end spaced a predetermined distance D1 apart, a position corresponding to the widened region of the resin filling section is designated as a gate section, and resin material is filled into the resin filling section from the gate section.