Double container and method for manufacturing the same

Abstract

To provide a double container capable of improving the dimensional accuracy of an outside air introduction hole.SOLUTION: According to the present invention, there is provided a double-walled container including a container body, wherein the container body is a biaxially stretched blow molded article, the container body includes an inner bag and an outer shell disposed to cover the inner bag, an outer peripheral surface of the outer shell is provided with first and second flange portions in order from an opening end side of the outer shell, and the outer shell is provided with a fresh air inlet in an intermediate region between the first and second flange portions. Since the double-walled container of the present invention is excellent in recyclability, it can be suitably used for producing a recycled material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a double container and a method for manufacturing the same. [Background technology]

[0002] Patent Document 1 discloses a method for producing a double-layered container by biaxially stretching blow molding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2022 / 215598 Summary of the Invention [Problem to be solved by the invention]

[0004] In the double container of Patent Document 1, an outside air inlet hole is provided in the container body, and a check valve is engaged and attached to this outside air inlet hole, so that the compressive force applied to the outer shell is transmitted to the inner bag and the outer shell returns to its original shape when the compressive force is removed.

[0005] In order to fit the check valve into the air inlet hole, the dimensional accuracy of the air inlet hole must be extremely high, but it is not easy to increase the dimensional accuracy of the air inlet hole.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a double container that can improve the dimensional accuracy of the outside air introduction hole. [Means for solving the problem]

[0007] According to the present invention, the following inventions are provided. [1] A double container comprising a container body, the container body being a biaxially stretched blow molded body, the container body comprising an inner bag and an outer shell arranged to cover the inner bag, the outer peripheral surface of the outer shell being provided with first and second flange portions in that order from the opening end side of the outer shell, and the outer shell being provided with an outside air inlet hole in the intermediate region between the first and second flange portions. [2] A double container as described in [1], wherein the double container is provided with an air flow regulating member that regulates the flow of air through the outside air inlet hole, and the air flow regulating member is positioned in the intermediate region. [3] A double container according to [2], wherein the air flow regulating member is a check valve having a valve body and a moving body, the moving body is configured to be movable within the space within the valve body, and the valve body is positioned in the intermediate region. [4] A double container as described in [3], wherein the valve body comprises a cylindrical portion having the space and an arm extending from the cylindrical portion, the arm having a protrusion, and the protrusion being inserted into a recess provided in the intermediate region. [5] A double container as described in [2], wherein the air flow regulating member is a check valve having a valve body and a moving body, the moving body is configured to be able to move within the space within the valve body, and the valve body is configured by the outer shell and the inner bag. [6] A double container comprising a container body and an air flow restricting member, wherein the container body comprises an inner bag and an outer shell arranged to cover the inner bag, the outer shell having an outside air inlet hole, the air flow restricting member comprising a valve body and a moving body, and a check valve configured to restrict the flow of air through the outside air inlet hole, the moving body being configured to be movable within the space within the valve body, the valve body comprising a tubular portion having the space and an arm extending from the tubular portion, the arm having a protrusion which is inserted into a recess provided in the outer shell. [7] A double container comprising a container body and an air flow regulating member, wherein the container body comprises an inner bag and an outer shell arranged to cover the inner bag, the outer shell having an outside air introduction hole, the air flow regulating member comprising a valve body and a moving body, and a check valve configured to regulate the flow of air through the outside air introduction hole, the moving body being configured to be movable within the space within the valve body, and the valve body being composed of the outer shell and the inner bag. [8] A method for manufacturing a double-layered container, comprising a biaxially stretched blow molding process, wherein in the biaxially stretched blow molding process, a preform is biaxially stretched blow molded, and the preform is constructed by placing an outer preform over an inner preform, and the outer preform has first and second flange portions provided in that order from the open end side of the outer preform, and an outside air introduction hole is provided in the outer preform in an intermediate region between the first and second flange portions. [Effects of the Invention]

[0008] In the double-walled container of the present invention, an air inlet hole is provided in the intermediate region between the first and second flanges of the outer shell. Since the intermediate region is hardly deformed during biaxially stretched blow molding, the dimensional accuracy of the air inlet hole can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view of a double container 1 according to a first embodiment of the present invention. The dashed-dotted line in the figure indicates the boundary line where the curvature of the faces that make up the surface shape changes. The same applies to the other figures. [Figure 2] 2 is an exploded perspective view of the container body 2 and the air flow regulation member 53 of the double container 1 of FIG. 1. FIG. [Figure 3] FIG. 3 is an enlarged view of the vicinity of the mouth 5 in FIG. [Figure 4] FIG. 2 is a vertical cross-sectional view of the double container 1 of FIG. [Figure 5] FIG. 5 is an exploded view of FIG. [Figure 6] Fig. 6A is a cross-sectional view taken along line AA in Fig. 4. Fig. 6B is an enlarged view of region B in Fig. 6A. [Figure 7] FIG. 2 is a perspective view showing a state in which the inner preform 14 and the outer preform 13 are separated. [Figure 8] 1 is a cross-sectional view showing a state in which a preform 15 is attached to a blow core 21 and brought close to a heater 32. FIG. [Figure 9] FIG. 2 is a cross-sectional view illustrating biaxial stretch blow molding of a preform 15. [Figure 10] FIG. 5 is a view corresponding to FIG. 4, showing a double container 1 according to a second embodiment of the present invention. [Figure 11] Fig. 11A is a cross-sectional view taken along line AA in Fig. 10. Fig. 11B is an enlarged view of region B in Fig. 11A. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Each feature can be an invention independently. In the following embodiments, elements not specified in the claims are optional and can be omitted. Any number of "0"s (for example, one or two) may be added to the end of numerical values ​​disclosed in the following description. For example, one or two "0"s may be added after "1.4" to make it "1.40" or "1.400."

[0011] The embodiments shown below include at least the inventions of the following aspects.

[0012] The invention of the first aspect is as follows: A double container comprising a container body, the container body is a biaxially stretched blow molded article, The container body includes an inner bag and an outer shell disposed to cover the inner bag, First and second flange portions are provided on the outer peripheral surface of the outer shell in this order from the open end side of the outer shell, The outer shell is provided with an air inlet hole in the intermediate region between the first and second flange portions, making it a double container.

[0013] The invention of the second aspect is as follows: A double container comprising a container body and an air flow restriction member, The container body includes an inner bag and an outer shell disposed to cover the inner bag, The outer shell is provided with an outside air introduction hole, the air flow regulating member is a check valve including a valve body and a moving body, and configured to regulate the flow of air through the outside air introduction hole, The movable body is configured to be movable within a space within the valve body, the valve body includes a cylindrical portion having the space and an arm extending from the cylindrical portion, The arm is provided with a protrusion, The protrusion is a double container inserted into a recess provided in the outer shell.

[0014] The invention of the third aspect is as follows: A double container comprising a container body and an air flow restriction member, The container body includes an inner bag and an outer shell disposed to cover the inner bag, The outer shell is provided with an outside air introduction hole, the air flow regulating member is a check valve including a valve body and a moving body, and configured to regulate the flow of air through the outside air introduction hole, The movable body is configured to be movable within a space within the valve body, The valve body is a double container constituted by the outer shell and the inner bag.

[0015] 1. First embodiment The double-sided container according to the first embodiment of the present invention will be described with reference to Figures 1 to 9. In the following description, terms relating to directions such as "upper" and "lower" refer to directions when the bottom 7 is in contact with the ground. In addition, in the following description, the "axial direction" refers to the direction in which the central axis C (shown in Figure 2) of the mouth 5 extends, in other words, the direction in which the inner bag 4 is pulled out from the container body 2. The "circumferential direction" refers to the direction of rotation around the central axis C of the mouth 5, in other words, the direction in which the inner bag 4 is rotated at the mouth 5 relative to the outer shell 3. Unless otherwise specified, "clockwise" and "counterclockwise" refer to directions as viewed from the top of the double-sided container 1.

[0016] 1-1. Structure of double container 1 As shown in Fig. 1, the double container 1 of the first embodiment of the present invention comprises a container body 2, a spout mounting member 8, and an air flow restricting member 53. Each component will be described in detail below.

[0017] <Basic configuration of container body 2> As shown in Figures 2 and 3, the container body 2 has a mouth 5, a body 6, and a bottom 7. The mouth 5 is a tubular (preferably cylindrical) portion having an open end 5c. The open end 5c is the open end of the container body 2 and also the open end of the inner bag 4. The mouth 5 has an engaging portion 4m to which a mouth attachment member 8 can be attached.

[0018] The body 6 is disposed adjacent to the mouth 5 on a side farther from the open end 5c than the mouth 5. The body 6 has a larger outer diameter (in this specification, "outer diameter" means the equivalent circular diameter when the cross section is not circular) than the mouth 5. The body 6 is cylindrical, and the bottom 7 is provided at the lower end of the body 6 and closes the lower end of the body 6. The body 6 has a shoulder 6b whose outer diameter increases with increasing distance from the mouth 5. The body 6 also has a body main body 6c on the bottom 7 side of the shoulder 6b. The body main body 6c has a shape in which the outer diameter is approximately constant toward the bottom 7, or a shape in which the diameter decreases toward the bottom 7, for example.

[0019] As shown in Fig. 5, the container body 2 includes an inner bag 4 and an outer shell 3 arranged to cover the inner bag 4. The inner bag 4 has an inner bag body 4d other than the protruding portion 4c housed within the outer shell 3. In the following description, the portions of the inner bag 4 that correspond to the mouth 5, body 6, and bottom 7 of the container body 2 will be referred to as the mouth 5, body 6, and bottom 7 of the inner bag 4, respectively. The same applies to the outer shell 3.

[0020] The container body 2 is a biaxially stretched blow molded article, and can be formed by biaxially stretching blow molding a preform 15, as will be described later.

[0021] <Detailed structure of outer shell 3 and inner bag 4> As shown in FIG. 5 , the inner bag 4 has a protrusion 4c that protrudes from the open end 3a of the outer shell 3. The inner bag 4 has a first tube 4a and a second tube 4b. The first tube 4a is disposed within the outer shell 3. The second tube 4b has a larger outer diameter than the first tube 4a and is disposed closer to the open end 5c of the inner bag 4 than the first tube 4a. The entire second tube 4b may be disposed outside the outer shell 3, or part or all of the second tube 4b may be disposed within the outer shell 3, with the remainder disposed outside the outer shell 3.

[0022] The lower surface 4b4 of the second tube 4b abuts against the outer shell 3. The lower surface 4b4 abuts against an inner bag support surface 3a3 provided on the outer shell 3. The lower surface 4b4 is supported by the inner bag support surface 3a3, thereby preventing the inner bag 4 from falling into the outer shell 3. The inner bag support surface 3a3 may be flush with the base surface 3a1 of the open end 3a, or may be provided at a higher or lower position than the base surface 3a1. In this embodiment, the inner bag support surface 3a3 is provided at a lower position than the base surface 3a1. Therefore, a portion of the second tube 4b is disposed inside the outer shell 3, and the remainder is disposed outside the outer shell 3. The base surface 3a1 is provided with an annular protrusion 3a2.

[0023] By having the lower surface 4b4 in close contact with the inner bag support surface 3a3, air leakage from the gap between the inner bag 4 and the outer shell 3 is suppressed, and the intermediate space between the inner bag 4 and the outer shell 3 can be made into a sealed space. Note that additional sealing means may be employed to more reliably suppress air leakage from the gap between the inner bag 4 and the outer shell 3. Examples of additional sealing means include a means for tightly contacting the mouth attachment member 8 with each of the outer shell 3 and the inner bag 4, and a means for tightly contacting the outer shell 3 and the inner bag 4 via an elastomer.

[0024] A cam mechanism 31 is preferably provided between the inner bag 4 and the outer shell 3. The cam mechanism 31 functions to displace the inner bag 4 in a direction that allows it to be removed from the container body 2 by rotating the inner bag 4 clockwise or counterclockwise relative to the outer shell 3. As shown in FIG. 6, the cam mechanism 31 can be configured, for example, with a ridge 4g provided on the outer peripheral surface of the inner bag 4 and a cam rail 3l provided on the inner peripheral surface of the outer shell 3. When the inner bag 4 is rotated relative to the outer shell 3 at the opening 5, the inner bag 4 is twisted and reduced in diameter, making it easier to pull out. The cam rail 3l is provided with an engaging ridge 3m that is positioned to restrict the movement of the ridge 4g, thereby preventing the inner bag 4 from rotating unexpectedly. The cam mechanism 31 is preferably provided in a position that does not interfere with the air inlet vent 3h. The cam mechanism 31 is also preferably provided in the intermediate region 3i to prevent deformation during biaxial stretch blow molding. Therefore, it is preferable that the cam mechanism 31 is provided in a position in the intermediate region 3i that does not interfere with the outside air introduction hole 3h.

[0025] As shown in Figures 3 and 5, first and second flange portions 3f1, 3f2 are provided on the outer peripheral surface of the outer shell 3 in this order from the opening end 3a of the outer shell 3. The first flange portion 3f1 is provided at a position adjacent to the opening end 3a. The outer shell 3 is provided with an air introduction hole 3h in an intermediate region 3i between the first and second flange portions 3f1, 3f2. Because the intermediate region 3i is hardly deformed during biaxial stretch blow molding, the dimensional accuracy of the air introduction hole 3h can be improved.

[0026] 5, the axial length L between the first and second flange portions 3f1, 3f2 is, for example, 3 to 9 mm, and preferably 4 to 7 mm (5 mm in this embodiment).Specific examples of the length L7 are 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, and 9.0 mm, and may be in a range between any two of the numerical values ​​exemplified here.

[0027] <Air flow control member 53> 1 and 4, the container body 2 is provided with an air flow restriction member 53 that restricts the flow of air through the outside air introduction hole 3h. The air flow restriction member 53 is disposed in the intermediate region 3i. This makes it possible to restrict the flow of air through the outside air introduction hole 3h without providing an air flow restriction member on the mouth-mounted member 8.

[0028] When the outer shell 3 is pressed from the outside of the container body 2 to discharge the contents of the inner bag 4, the air flow restricting member 53 is configured to either allow air to flow out of the intermediate space between the outer shell 3 and the inner bag 4 to an extent that the pressure in the intermediate space increases to facilitate the discharge of the contents, or to not allow air to flow out. When pressure is stopped, the air flow restricting member 53 is configured to allow air to flow into the intermediate space from outside the container body 2 so that the shape of the outer shell 3 is restored.

[0029] The air flow restricting member 53 may be a check valve 9 that restricts the flow of air as the movable body moves, or a breathable membrane that allows a small amount of air to flow. The breathable membrane may be a microporous membrane made primarily of polytetrafluoroethylene (PTFE), for example, and the microporous membrane may be a composite membrane containing nonwoven fabric or polyethylene terephthalate (PET) mesh. The means for disposing the air flow restricting member 53 in the intermediate region 3i is not limited, and may be any of engagement, press-fitting, welding, adhesion, etc.

[0030] The check valve 9 has the function of preventing air from flowing out through the outside air introduction hole 3h while allowing air to flow in through the outside air introduction hole 3h. As shown in FIG. 6B, the check valve 9 includes a valve body 9a and a movable body 9b. The movable body 9b is configured to be movable within a space 9a3 within the valve body 9a. The valve body 9a is attached to the intermediate region 3i. The space 9a3 includes a first opening 9a1 on the outside space side and a second opening 9a2 on the intermediate space side. The valve body 9a includes a first abutment portion 9a4 that abuts against the movable body 9b when it moves toward the outside space and a second abutment portion 9a5 that abuts against the movable body 9b when it moves toward the intermediate space. When the movable body 9b abuts against the first abutment portion 9a4, air is prevented from flowing out through the outside air introduction hole 3h. When the movable body 9b is in contact with the second contact portion 9a5, air is allowed to flow in through the outside air introduction hole 3h.

[0031] In this embodiment, the valve body 9a includes a cylindrical portion 9c having a space 9a3 and an arm 9f extending from the cylindrical portion 9c. The arm 9f is provided with a protrusion 9f1. The protrusion 9f1 is inserted into a recess 3j provided in the intermediate region 3i. This stably positions the valve body 9a in the intermediate region 3i. The protrusion 9f1 is provided with a claw portion 9f2, and the recess 3j is provided with an engaging protrusion 3j1 that engages with the claw portion 9f2. The engagement of the claw portion 9f2 with the engaging protrusion 3j1 prevents the arm 9f from coming off the recess 3j. The valve body 9a may be positioned in the intermediate region 3i by press-fitting, welding, adhesive bonding, or the like. Preferably, the valve body 9a includes a pair of arms 9f extending from the cylindrical portion 9c, and each of the pair of arms 9f is provided with a protrusion 9f1. Note that, from the perspective of a configuration for mounting the valve body 9a to the outer shell 3, the valve body 9a may be mounted to any portion of the outer shell 3. In this case, the protrusion 9f1 of the arm 9f is inserted into a recess 3j provided in an arbitrary position on the outer shell 3.

[0032] In this embodiment, the valve body 9a is constructed as a single unit, but the valve body 9a may also be constructed by combining an attachment member attached to the intermediate region 3i with the outer shell 3. In this case, it is preferable that the attachment member be provided with a first opening 9a1 and a first abutment portion 9a4, and that the outer shell 3 be provided with a second opening 9a2 and a second abutment portion 9a5. The attachment member can be attached to the intermediate region 3i by engagement, press-fitting, welding, adhesive bonding, or the like.

[0033] <Configuration of mouth-mounted member 8> The spout attachment member 8 is a member that is attached to the spout 5 of the container body 2. In this embodiment, the spout attachment member 8 is a cap 8a, but it may also be another member such as a pump. As shown in FIG. 5, the spout attachment member 8 has an engaging portion 8b that can engage with the engaging portion 4m. When the engaging portion 8b engages with the engaging portion 4m, the spout attachment member 8 engages with the spout 5 (preferably the protruding portion 4c) of the inner bag 4 in the axial direction.

[0034] The spout attachment member 8 preferably also circumferentially engages with the spout 5 (preferably the protruding portion 4c) of the inner bag 4. In this embodiment, as shown in Fig. 3, the inner bag 4 is provided with a circumferential engagement portion 4mb at a position farther from the open end 5c than the engagement portion 4m, and the spout attachment member 8 circumferentially engages with the spout 5 of the inner bag 4 at the circumferential engagement portion 4mb. The circumferential engagement portion 4mb preferably has a plurality of engagement protrusions 4c2 spaced apart along the circumferential direction, and when the engagement portion 8b is pressed against the engagement protrusions 4c2, the engagement portion 8b and the engagement protrusions 4c2 engage with each other in the circumferential direction.

[0035] The mouth-mounted member 8 preferably has a discharge port 8d for discharging the contents in the inner bag 4. The mouth-mounted member 8 also preferably includes a nozzle 8c.

[0036] The cap 8a preferably includes a cap body 41 and an overcap 42. The cap body 41 is configured to be able to engage with the protrusion 4c and includes a discharge port 8d. The overcap 42 is configured to be able to open and close the discharge port 8d.

[0037] The cap body 41 includes an outer tube 41a, an inner tube 41b, a nozzle 8c, and an upper wall 41d. The inner tube 41b is disposed inside the outer tube 41a. The outer tube 41a and inner tube 41b are connected via the upper wall 41d. The nozzle 8c is disposed above the upper wall 41d. A flow hole 41i is provided in the upper wall 41d, and the flow passage of the inner tube 41b and the nozzle 8c are connected through the flow hole 41i. The tip of the nozzle 8c serves as the discharge port 8d. The inner tube 41b is inserted into the protruding portion 4c and is in close contact with the inner surface 4f1 of the cylindrical seal portion 4f. An engagement portion 8b is provided on the inner peripheral surface of the outer tube 41a. The cap body 41 is provided with a discharge valve 44. The discharge valve 44 is configured to allow the contents to be discharged while preventing outside air from entering the inner bag 4. In this embodiment, the discharge valve 44 is provided in the nozzle 8c, but it may also be provided in, for example, the upper wall 41d.

[0038] <Attachment of mouth attachment member 8> As shown in FIG. 5, the mouth-mounting member 8 can be attached to the mouth 5 with the first flange 3f1 supported. The mouth-mounting member 8 is preferably a stopper type. With the first flange 3f1 supported, the mouth-mounting member 8 is placed over the protruding portion 4c. When a downward force is applied to the mouth-mounting member 8 in this state, the engaging portion 8b overcomes the engaging portion 4m, and the engaging portions 8b and 4m engage axially, thereby attaching the mouth-mounting member 8 to the mouth 5 (preferably the protruding portion 4c). In this embodiment, the mouth-mounting member 8 may be attached to the mouth 5 (preferably the protruding portion 4c) using a screw mechanism. The first flange 3f1 is provided as a support ring, and it is preferable that the first flange 3f1 does not engage with the mouth-mounting member 8. The second flange 3f2 may be too far from the open end 5c and may not fit into a device (e.g., a device conforming to the F-port standard) for attaching the mouth-mounting member 8. Therefore, it is preferable to use the first flange 3f1 as a support ring.

[0039] <Use of double container 1> In this embodiment, the opening-mounted member 8 is provided with a discharge valve 44, which causes the inner bag 4 to contract as the contents of the inner bag 4 are discharged. Furthermore, an outside air inlet hole 3h is provided through the outer shell 3, allowing the inner bag 4 to separate from the outer shell 3 and contract as the contents are discharged, creating a peelable container. Furthermore, an air flow restriction member 53 is provided to restrict the flow of air through the outside air inlet hole 3h, so that when the outer shell 3 is compressed, the pressure in the intermediate space increases, allowing the contents to be discharged from the inner bag 4. When the compressive force on the outer shell 3 is removed and the outer shell 3 returns to its original shape, outside air is introduced into the intermediate space, allowing the outer shell 3 to quickly restore its original shape. Therefore, this embodiment makes it possible to create a squeeze-type peelable container.

[0040] <Pull out inner bag 4> The mouth attachment member 8 is axially engaged with the mouth 5 of the inner bag 4, so by pulling the mouth attachment member 8, the inner bag 4 can be pulled out of the container body 2. Furthermore, if the mouth attachment member 8 is also circumferentially engaged with the mouth 5 of the inner bag 4, the inner bag 4 can be twisted and reduced in diameter by rotating the mouth attachment member 8. This reduces the force required to pull out the inner bag 4.

[0041] Furthermore, if a cam mechanism is provided between the inner bag 4 and the outer shell 3, the inner bag 4 is configured to move in a direction that causes it to come out of the container body 2 as it rotates. With this configuration, by rotating the mouth attachment member 8, the inner bag 4 can be moved in a direction that causes it to come out of the container body 2 while twisting, and then by pulling the mouth attachment member 8, the inner bag 4 can be pulled out of the container body 2.

[0042] 1-2. Manufacturing method of double container 1 The container body 2 can be manufactured by biaxially stretching blow molding the preform 15 shown in Figures 7 and 8. After the biaxially stretching blow molding, an arrangement step can be performed in which an air flow regulating member 53 is arranged in the intermediate region 3i. Furthermore, the double container 1 can be manufactured by attaching the mouth attachment member 8 to the container body 2.

[0043] 1-2-1. Preform 15 The preform 15 includes an inner preform 14 that will become the inner bag 4 and an outer preform 13 that will become the outer shell 3.

[0044] As shown in Fig. 7, the inner preform 14 is cylindrical with a bottom and includes a mouth portion 14a, a body portion 14b, and a bottom portion 14c. A protrusion 14d is provided on the mouth portion 14a. As shown in Figs. 7 and 8, the protrusion 14d is a portion of the preform 15 that protrudes from the open end 13f of the outer preform 13. The protrusion 14d does not deform during molding and remains in its original shape to become the protrusion 4c. The bottom portion 14c is provided to close the lower end of the body portion 14b.

[0045] 7, the outer preform 13 is cylindrical and has a bottom, a mouth 13a, a body 13b, and a bottom 13c. The bottom 13c is provided to close the lower end of the body 13b. The outer preform 13 has first and second flanges 13f1 and 13f2 and an outside air introduction hole 13h disposed in an intermediate region 13i therebetween. The first and second flanges 13f1 and 13f2, the intermediate region 13i, and the outside air introduction hole 13h correspond to the first and second flanges 3f1 and 3f2, the intermediate region 3i, and the outside air introduction hole 3h of the container body 2, respectively.

[0046] 8, a preform 15 can be formed by covering an inner preform 14 with an outer preform 13. In the preform 15, the mouth portion 14a faces the mouth portion 13a, and the body portion 14b faces the body portion 13b.

[0047] The mouth portions 13a and 14a become the mouth portion 15a of the preform 15, the body portions 13b and 14b become the body portion 15b of the preform 15, and the bottom portions 13c and 14c become the bottom portion 15c of the preform 15. In this embodiment, the portion of the second flange portion 13f2 closer to the bottom portion 15c than the lower surface 13f3 is mainly stretched during biaxial stretch blow molding. The portion of the second flange portion 13f2 closer to the opening end 15f than the lower surface 13f3 is hardly deformed during molding. With regard to the portion that is hardly deformed during biaxial stretch molding, the contents explained in relation to the container body 2 can also be applied to the preform 15, as long as it is not contrary to the spirit thereof.

[0048] <Materials and manufacturing methods for inner preform 14, outer preform 13, and preform 15> The inner preform 14 and the outer preform 13 can be formed from a thermoplastic resin such as polyester (e.g., PET) or polyolefin (e.g., polypropylene, polyethylene). The inner preform 14 and the outer preform 13 can be formed by direct blow molding or injection molding. The inner preform 14 is preferably formed by direct blow molding using a tubular parison in a molten state. Direct blow molding has the advantage that it is easier to make thinner and multi-layered parts than injection molding.

[0049] 1-2-2. Biaxial stretch blow molding process The biaxial stretch blow molding process will be described with reference to Figures 8 and 9. In the biaxial stretch blow molding process, the preform 15 is attached to the blow core 21 so that the insertion portion 21b of the blow core 21 is positioned within the preform 15, and the preform 15 is then biaxially stretch blow molded into the shape of the container body 2.

[0050] In one example, the biaxial stretch blow molding process includes a mounting step, a heating step, and a stretching step. Each step will be described below.

[0051] <Installation process> In the mounting step, as shown in FIG. 8, the preform 15 is mounted to the blow core 21 so that the insertion portion 21b of the blow core 21 is disposed within the preform 15. The blow core 21 includes a base portion 21a, an insertion portion 21b, and a through-hole 21c. The insertion portion 21b is provided so as to protrude from the base portion 21a. The insertion portion 21b is inserted into the preform 15.

[0052] <Heating process> The heating process can be performed using a heating device 35 shown in FIG. 8. In the heating process, the preform 15 is heated and softened to a softened state. In one example, the heating process can be performed by placing the preform 15 in close proximity to a heater 32 while the preform 15 is attached to a blow core 21, as shown in FIG. 8. The heating process is performed by covering the second flange portion 13f2 provided on the preform 15 with a heat shield 33 and heating a portion of the second flange portion 13f2 closer to the bottom 15c than the lower surface 13f3. This softens the heated portion. On the other hand, the portion of the second flange portion 13f2 closer to the opening end 15f than the lower surface 13f3 receives little or no heat from the heater 32 and is not softened. Furthermore, deformation of the intermediate region 13i between the first and second flange portions 13f1 and 13f2 is further suppressed by the first and second flange portions 13f1 and 13f2. Therefore, during biaxial stretch blow molding, the outside air introduction holes 13h arranged in the intermediate region 13i change shape little and become the outside air introduction holes 3h of the container body 2. In one example, the preform 15 can be heated while being rotated. Also, in one example, the heater 32 is composed of multiple rod-shaped heaters arranged along the side surface of the preform 15, but other configurations are also possible.

[0053] <Stretching process> The stretching step can be performed using a blow molding device 36 shown in Fig. 9. In the stretching step, the softened preform 15 is stretched to form the shape of the container body 2. In one example, the stretching step includes a first stretching step and a second stretching step.

[0054] <First stretching process> In the first stretching step, the preform 15 is stretched along a first axial direction (i.e., the vertical direction). The first axis is, for example, a direction parallel to the central axis C of the mouth portion 5, which is the vertical direction in FIG. 9. In one example, as shown in FIG. 9, this step can be performed by setting the heated preform 15 in a molding die 23, supporting the bottom 15c of the preform 15 with a bottom support die 22, and then pressing a stretch rod 25 inserted through a through hole 21c provided in a blow core 21 against the inner bottom surface of the inner preform 14 to stretch it. At this time, it is preferable to retract the bottom support die 22 in synchronization with the stretching of the stretch rod 25. This allows the preform 15 to be stably stretched.

[0055] The preform 15 can be transferred from the heating device 35 to the blow molding device 36 while supported by the blow core 21. The molding die 23 is composed of a split mold that can be opened and closed, and includes a cavity surface 23a corresponding to the outer surface shape of the container body 2 and a flange abutment surface 23d against which the lower surface 13f3 of the second flange portion 13f2 abuts. The first stretching step can be performed with the lower surface 13f3 of the second flange portion 13f2 abutting against the flange abutment surface 23d. If the second flange portion 13f2 were not present, the area closer to the bottom 15c than the lower surface of the first flange portion 13f1 would be heated, and the lower surface of the first flange portion 13f1 would be abutted against the flange abutment surface 23d for biaxial stretch blow molding, which would make the outside air introduction hole 13h more susceptible to deformation during biaxial stretch blow molding. In this embodiment, the outside air introduction hole 13h is provided in the intermediate region 13i between the first and second flange portions 13f1, f2, thereby suppressing deformation of the outside air introduction hole 13h.

[0056] <Second stretching process> In the second stretching step, after the first stretching step, air is blown into the inner preform 14 to stretch (i.e., expand) the preform 15 in the second axial direction (i.e., the lateral direction) and shape it into the shape of the cavity surface 23a, thereby obtaining the container body 2 shown in Fig. 2. Air can be blown in through the through holes 21c provided in the blow core 21.

[0057] 2. Second embodiment A second embodiment of the present invention will be described with reference to Figures 10 and 11. This embodiment is similar to the first embodiment, and the details described in the first embodiment can also be applied to this embodiment as long as they do not contradict the spirit of the first embodiment. This embodiment differs mainly from the first embodiment in the configuration of the check valve 9. The following description will focus on these differences.

[0058] In this embodiment, the valve body 9a of the check valve 9 is composed of an outer shell 3 and an inner bag 4. The outer shell 3 has a recess 3k on its inner circumferential surface at a position communicating with the outside air introduction hole 3h. The inner bag 4 has a recess 4n on its outer circumferential surface at a position facing the outside air introduction hole 3h. The movable body 9b is disposed in a space 9a3 formed by the recess 3k and the recess 4n. Note that the space 9a3 may be formed only by the recess 3k or only by the recess 4n.

[0059] The valve body 9a has a first contact portion 9a4 that contacts the moving body 9b when it moves toward the external space, and a second contact portion 9a5 that contacts the moving body 9b when it moves toward the intermediate space. When the moving body 9b contacts the first contact portion 9a4, air is prevented from flowing out through the outside air introduction hole 3h. When the moving body 9b contacts the second contact portion 9a5, air is allowed to flow in through the outside air introduction hole 3h.

[0060] According to this embodiment, the valve body 9a can be mounted without using any additional components. From the viewpoint that the valve body 9a is constituted by the outer shell 3 and the inner bag 4, it is not essential that the check valve 9 be disposed in the intermediate region 3i, and it may be disposed in any position.

[0061] 3. Other embodiments In the above embodiment, the air flow restricting member 53 is disposed in the intermediate region 3i, but the air flow restricting member 53 can be disposed at any position where it can restrict the flow of air through the outside air introduction hole 3h. The air flow restricting member 53 can be disposed on the mouth-attached member 8, for example. [Explanation of symbols]

[0062] 1:Double container 2: Container body 3: Outer shell 3a: Open end 3a1: Base surface 3a2: Annular convex part 3a3: inner bag support surface 3f1: First flange 3f2: Second flange part 3h: Outside air intake 3i: intermediate area 3j: Recess 3j1: Engagement protrusion 3k: recess 3l: Cam rail 3m: Engagement convex part 4: Inner bag 4a: 1st cylinder 4b: 2nd cylinder 4b4:Bottom surface 4c:Protrusion 4c2: Engagement convex part 4d: Inner bag body 4f: Seal cylinder 4f1: Inner surface 4g: Convex strip 4m: Engagement part 4mb: Circumferential engagement part 4n: recess 5: Mouth 5c: Open end 6: Body 6b:Shoulder 6c: Body 7: Bottom 8: Mouth attachment member 8a: Cap 8b: Engagement part 8c: Nozzle 8d:Discharge port 9: Check valve 9a: Valve body 9a1: 1st opening 9a2: 2nd opening 9a3 :Space 9a4: 1st contact part 9a5: 2nd contact part 9b: Mobile object 9c:Cylinder part 9f: Arm 9f1: Protrusion 9f2: Claw part 13: Outer preform 13a: Mouth 13b: Torso 13c: Bottom 13f: Open end 13f1: First flange 13f2: Second flange part 13f3: Bottom surface 13h: Outside air intake 13i: intermediate area 14: Inner preform 14a: Mouth 14b: Torso 14c: Bottom 14d:Protrusion 15: Preform 15a: Mouth 15b: Body 15c: bottom 15f: Open end 21: Blow Core 21a: base 21b: Insertion part 21c: Through hole 22: Bottom support type 23: Molding mold 23a: Cavity surface 23d: Flange contact surface 25: Stretching rod 31: Cam mechanism 32: Heater 33: Heat shielding section 35: Heating device 36: Blow molding equipment 41: Cap body 41a: Outer cylinder 41b: Inner cylinder 41d: Upper wall 41i :Flow hole 42: Overcap 44: Discharge valve 53: Air flow control member C: Central axis

Claims

1. A double container comprising a container body, the container body is a biaxially stretched blow molded article, The container body includes an inner bag and an outer shell disposed to cover the inner bag, a first flange portion and a second flange portion are provided on an outer peripheral surface of the outer shell in this order from an open end side of the outer shell, The outer shell has an air inlet hole in an intermediate region between the first and second flange portions.

2. The double container according to claim 1, the double container includes an air flow restriction member that restricts the flow of air through the outside air introduction hole, The air flow restriction member is disposed in the intermediate region.

3. The double container according to claim 2, the air flow restriction member is a check valve including a valve body and a moving body, The movable body is configured to be movable within a space within the valve body, The valve body is disposed in the intermediate region.

4. The double container according to claim 3, the valve body includes a cylindrical portion having the space and an arm extending from the cylindrical portion, The arm is provided with a protrusion, The protrusion is inserted into a recess provided in the intermediate region.

5. The double container according to claim 2, the air flow restriction member is a check valve including a valve body and a moving body, The movable body is configured to be movable within a space within the valve body, The valve body is a double container constituted by the outer shell and the inner bag.

6. A double container comprising a container body and an air flow restriction member, The container body includes an inner bag and an outer shell disposed to cover the inner bag, The outer shell is provided with an outside air introduction hole, the air flow regulating member is a check valve including a valve body and a moving body, and configured to regulate the flow of air through the outside air introduction hole, The movable body is configured to be movable within a space within the valve body, the valve body includes a cylindrical portion having the space and an arm extending from the cylindrical portion, The arm is provided with a protrusion, The protrusion is inserted into a recess provided in the outer shell.

7. A double container comprising a container body and an air flow restriction member, The container body includes an inner bag and an outer shell disposed to cover the inner bag, The outer shell is provided with an outside air introduction hole, the air flow regulating member is a check valve including a valve body and a moving body, and configured to regulate the flow of air through the outside air introduction hole, The movable body is configured to be movable within a space within the valve body, The valve body is a double container constituted by the outer shell and the inner bag.

8. A method for manufacturing a double-layered container, comprising a biaxially stretched blow molding process, In the biaxially stretched blow molding step, the preform is biaxially stretched blow molded, The preform is configured by covering an outer preform with an inner preform, the outer preform is provided with first and second flange portions in this order from an open end side of the outer preform, The method wherein the outer preform has an air inlet hole in an intermediate region between the first and second flange portions.

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