Method for dispensing contents from a double-walled container

Abstract

To provide a method for discharging a content in a double container which enables a reduction in the final residual amount of a content.SOLUTION: According to the invention, a method for discharging a content in a double container is provided, in which the double container comprises a container body and a cap fitted on the mouth part of the container body, and in which the container body comprises an inner bag and an outer shell arranged to cover the inner bag, with the content stored in the inner bag, and the cap engaged with the inner bag. This method includes an extraction step and a discharge step: in the extraction step, the inner bag is extracted out of the container body in the condition that the cap remains engaged with the inner bag with a part of the content remaining in the inner bag; and in the discharge step, the content remaining in the inner bag is discharged after extraction out of the container body.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for discharging the contents in a double container.

Background Art

[0002] Conventionally, a double container including a container body having an outer shell and an inner bag is known. For example, Patent Document 1 discloses a double container formed by performing biaxial stretch blow molding in a state where an outer shell preform and an inner bag preform are overlapped.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in such a double container, it is desired that the contents of the inner bag can be used up to the end, and it is desired to minimize the residual amount (hereinafter, "final residual amount") when further discharge becomes impossible.

[0005] The present invention has been made in view of such circumstances, and provides a method for discharging the contents in a double container capable of reducing the final residual amount of the contents.

Means for Solving the Problems

[0006] According to the present invention, the following invention is provided. [1] A method for discharging contents from a double-walled container, wherein the double-walled container comprises a container body and a cap fitted to the mouth of the container body, the container body comprises an inner bag and an outer shell positioned to cover the inner bag, the contents are contained in the inner bag, the cap is engaged with the inner bag, and the method comprises a withdrawal step and a discharge step, wherein in the withdrawal step, the inner bag is withdrawn from the container body with a portion of the contents remaining in the inner bag and the cap engaged with the inner bag, and in the discharge step, the contents remaining in the inner bag are discharged after the inner bag has been withdrawn from the container body. A method according to [2][1], wherein the bottom of the container body is provided with a recess having a flattened cross-section. A method according to [3] [1] or [2], wherein the inner bag comprises an annular projection that engages with the cap in the axial direction and an engaging projection that engages with the cap in the circumferential direction, the lower surface of the engaging projection being flush with the lower surface of the annular projection or positioned closer to the opening end of the inner bag than the lower surface of the annular projection. A method according to any one of [4][1] to [3], wherein the inner bag includes a thin-walled portion having a wall thickness of 100 μm or less.

[0007] In this invention, the inner bag is pulled out of the container body while the cap is engaged with the inner bag, and then the contents remaining in the inner bag are discharged. Since the inner bag is more flexible than the outer shell, the contents are easier to discharge, and according to the method of this invention, the final amount of residual contents can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a double-walled container 1 according to the first embodiment of the present invention. The dashed lines in the figure represent boundary lines where the curvature of the surfaces constituting the surface shape changes. The same applies to the other figures. [Figure 2] Figure 1 is an exploded perspective view. [Figure 3] This is a magnified view of region A in Figure 2. [Figure 4]Figure 3 is an exploded perspective view. Only a portion of the inner bag 4 near the opening end 5c is shown. [Figure 5] This is a perspective view of the vicinity of the open end of the outer shell 3. [Figure 6] This is a perspective view of the overcap 27 and inner stopper 26, seen from a diagonal downward angle. [Figure 7] Figure 7A shows the inner stopper 26 installed in the inner bag 4. The inner bag 4 is a perspective view showing the vicinity of the opening 5, and the inner stopper 26 is a longitudinal cross-sectional perspective view. Figure 7B is a longitudinal cross-sectional perspective view of the inner stopper 26. [Figure 8] This is a longitudinal cross-sectional view of the double container 1 shown in Figure 1, passing through the center of the mouth 5, before the overcap 27 is opened. [Figure 9] This is a front view showing the container body 2 and the mouth attachment member 8 with the shrink film 33 attached to cover them. [Figure 10] This is a perspective view of the container body 2 from below. [Figure 11] This is a vertical cross-sectional view passing through the center of the mouth 5 of the container body 2. [Figure 12] Figures 12A to 12C are the AA, BB, and CC cross-sectional views from Figure 11, respectively. [Figure 13] This is a cross-sectional view corresponding to Figure 12C, showing that a bent shape 2c is easily formed when the inner bag 4 is rotated relative to the outer shell 3. [Figure 14] This is a perspective view of the inner bag 4 with the cap 8a attached. [Figure 15] This diagram shows the layer structure of the inner bag 4. [Figure 16] This is a perspective view showing the inner preform 14 and outer preform 13 separated. [Figure 17] Figure 17A is a front view of the inner preform 14, Figure 17B is a right side view of the inner preform 14, and Figures 17C to 17D are perspective views of the area near the bottom of the inner preform 14, viewed from diagonally below. [Figure 18] This is a perspective view showing a preform 15 constructed by placing an outer preform 13 over an inner preform 14. [Figure 19] A cross-sectional view of a state in which a tubular parison 34 is disposed between split molds 35 and 36 in an open state. [Figure 20] A cross-sectional view after forming a molded body 38 by closing the split molds 35 and 36 and blowing air thereinto. [Figure 21] FIG. 21A is a cross-sectional view showing a state after removing the molded body 38 from the split molds 35 and 36 and removing burrs 39 from the state of FIG. 20. FIG. 21B is an enlarged view of region B in FIG. 21A. [Figure 22] FIG. 22A is a cross-sectional view showing a state after cutting out a bag portion 40 from the state of FIG. 21 to form an inner preform 14. FIG. 22B is an enlarged view of region B in FIG. 22A. FIG. 22C is a view corresponding to FIG. 22B when burrs 14p remain at the open end of the inner preform 14. [Figure 23] FIG. 23A is an enlarged view of a portion corresponding to region A in FIG. 22A in a form in which no stretching suppression structure is provided in the protruding seal portion 42. FIG. 23B shows a portion corresponding to FIG. 23A after biaxial stretch blow molding. [Figure 24] FIG. 24A is an enlarged view of region A in FIG. 22A. FIG. 24B shows a state after bending the protruding seal portion 42 to form a stretching suppression structure from the state of FIG. 24A, and FIG. 24C shows a portion corresponding to FIG. 24B after biaxial stretch blow molding of the inner preform 14 in which the stretching suppression structure is introduced. [Figure 25] FIG. 25A is a perspective view near the bottom of the inner preform 14 in the second embodiment of the present invention. FIG. 25B is a cross-sectional view of a cross-section perpendicular to the longitudinal direction of the protruding seal portion 42 of the inner preform 14 in FIG. 25A. FIG. 25C is an enlarged view of region C in FIG. 25B. In this form, the protruding seal portion 42 serves as a stretching suppression structure without post-processing. [Figure 26]Figure 26A is a perspective view of the vicinity of the bottom of the inner preform 14 in a third embodiment of the present invention. Figure 26B is a cross-sectional view of the inner preform 14 in Figure 26A, perpendicular to the longitudinal direction of the protruding seal portion 42. Figure 26C is an enlarged view of region C in Figure 26B. Figure 26D shows the state after the protruding seal portion 42 in Figure 26C has been remelted to form a stretch-suppressing structure. [Figure 27] Figure 27A is a perspective view of the vicinity of the bottom of the inner preform 14 in the fourth embodiment of the present invention. Figure 27B is a cross-sectional view of the inner preform 14 of Figure 27A, perpendicular to the longitudinal direction of the protruding seal portion 42. Figure 27C is an enlarged view of region C in Figure 27B. Figure 27D shows the state after the protruding seal portion 42 in Figure 27C has been bent to form a stretch-suppressing structure. [Figure 28] Figure 28A is a perspective view of the vicinity of the bottom of the inner preform 14 in the fifth embodiment of the present invention. Figure 28B is a cross-sectional view of the inner preform 14 in Figure 28A, perpendicular to the longitudinal direction of the protruding seal portion 42. Figure 28C is an enlarged view of region C in Figure 28B. Figure 28D shows the state after the protruding seal portion 42 in Figure 28C has been bent to form a stretch-suppressing structure. [Figure 29] This is a perspective view of the internal preform 14 in the sixth embodiment of the present invention. [Figure 30] This is a perspective view of the inner preform 14 and outer preform 13 in the seventh embodiment of the present invention. [Figure 31] This is a perspective view of the inner preform 14 and outer preform 13, which have the same configuration as the seventh embodiment of the present invention, except that the protruding seal portion 42 does not have an elongation suppression structure. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below. The various features shown in the embodiments below can be combined with each other. Furthermore, each feature constitutes an independent invention.

[0010] In the embodiments shown below, the invention of the first to ninth aspects is disclosed, and the claims relate to at least a portion thereof. The first to fifth embodiments relate to the first to ninth aspects. The sixth to seventh embodiments relate to the first to third and fifth to ninth aspects.

[0011] (First perspective) From this perspective, a method for manufacturing a double-walled container is provided, comprising the step of manufacturing a container body having an inner bag and an outer shell covering it by biaxially stretched blow molding a preform constructed by covering an inner preform with an outer preform, wherein the inner preform is formed by direct blow molding using a molten cylindrical parison, the inner preform is provided with a protruding seal portion which protrudes from the main body of the inner preform and is formed by welding the inner surfaces of the cylindrical parisons together, and the protruding seal portion is provided with a stretch-inhibiting structure which suppresses the stretching of the seal portion during the biaxial stretched blow molding.

[0012] (Second perspective) From this perspective, a method for manufacturing a double-walled container is provided, comprising the step of manufacturing a container body having an inner bag and an outer shell covering it by biaxial stretch blow molding a preform constructed by covering an inner preform with an outer preform, wherein the inner preform is formed by direct blow molding using a molten cylindrical parison, the mouth of the inner preform is provided with an engaging portion used for pulling the inner bag out of the container body, and if the outer diameter of the inner preform at the mouth is D1, the total height of the inner preform is H, and the outer diameter of the inner preform at a height position where the height from the bottom of the inner preform is 0.1H is D2, then D2 / D1 is 0.35 or more.

[0013] (Third perspective) From this perspective, a method for manufacturing a double-walled container is provided, comprising the step of manufacturing a container body having an inner bag and an outer shell covering it by biaxially stretch blow molding a preform constructed by covering an inner preform with an outer preform, wherein the inner preform is formed by direct blow molding using a molten cylindrical parison, the inner bag includes a thin-walled portion with a wall thickness of 100 μm or less, and the inner preform has an uneven shape on the outer surface of the region including the portion corresponding to the thin-walled portion, or a lubricant is present.

[0014] (Fourth perspective) From this perspective, a method for manufacturing a double-walled container is provided, comprising the step of manufacturing a container body having an inner bag and an outer shell covering it by biaxial stretch blow molding a preform constructed by covering an inner preform with an outer preform, wherein the inner preform is formed by direct blow molding using a molten cylindrical parison, the mouth of the inner preform is provided with an engaging portion used to pull the inner bag out of the container body, if the outer diameter of the inner preform at the mouth is D1 and the outer diameter of the cylindrical parison is D3, then D1 / D3 is 1.5 or more, and the opening end of the inner preform is provided with an expanding structure to suppress deformation of the mouth.

[0015] (Fifth perspective) In this view, a double-walled container is provided, comprising a container body and a mouth attachment member, wherein the container body comprises an inner bag and an outer shell disposed to cover the inner bag, and the mouth attachment member is attached to the mouth of the container body by a stopper, and is configured such that the inner bag moves in a direction away from the container body by rotating the mouth attachment member relative to the outer shell.

[0016] (6th perspective) In this view, a double-walled container is provided, comprising a container body, a mouth attachment member, and a shrink film attached so as to cover the container body and the mouth attachment member, wherein the container body comprises an inner bag and an outer shell disposed to cover the inner bag, the mouth attachment member comprises a stopper and an overcap, the stopper is engaged with the mouth of the inner bag in the circumferential and axial directions, the overcap is engaged with the stopper and configured such that the inner bag moves in a direction away from the container body by rotating the stopper relative to the outer shell, and the shrink film is attached in a covering state that covers the container body and the stopper but not the overcap, or has an easy-cut line so that the covering state is achieved after removing a part of the shrink film.

[0017] (Perspective 7) In this view, a method for discharging contents from a double-walled container is provided, wherein the double-walled container comprises a container body and a cap attached to the mouth of the container body, the container body comprises an inner bag and an outer shell positioned to cover the inner bag, the contents are contained within the inner bag, the cap is engaged with the inner bag, and the method comprises a withdrawal step and a discharge step, wherein in the withdrawal step, the inner bag is withdrawn from the container body with a portion of the contents remaining in the inner bag and the cap engaged with the inner bag, and in the discharge step, the contents remaining in the inner bag after being withdrawn from the container body are discharged.

[0018] (Perspective 8) In this view, a double-walled container is provided, comprising a container body, wherein the container body comprises an inner bag and an outer shell disposed to cover the inner bag, and, if the total height of the container body is J, the container body has three or more corners spaced apart in the circumferential direction in a cross-section at a position 0.2J from the bottom surface of the container body, and connecting portions with a radius of curvature larger than that of the corners are provided between the corners.

[0019] (Perspective 9) From this perspective, a double-walled container is provided, comprising a container body, wherein the container body comprises an inner bag and an outer shell disposed to cover the inner bag, and the inner bag comprises, in order from the inside of the container body, an inner layer, a gas barrier layer, and an outer layer.

[0020] 1. First Embodiment 1-1. Composition of Double Container 1 <Basic configuration> As shown in Figure 1, the double-walled container 1 of the first embodiment of the present invention comprises a container body 2 and a mouth attachment member 8.

[0021] As shown in Figures 2 and 3, the container body 2 comprises a mouth portion 5, a body portion 6, and a bottom portion 7. The mouth portion 5 is a cylindrical (preferably cylindrical) portion having an open end 5c. The mouth portion 5 is equipped with an engaging portion 4m to which a mouth portion attachment member 8, such as a cap or a pump, can be attached. Details of the engaging portion 4m will be described later. The mouth portion 5 is provided with a flange 5b. The flange 5b can be used to support the mouth portion 5 when attaching a mouth portion attachment member 8 to the mouth portion 5.

[0022] The body portion 6 is positioned adjacent to the mouth portion 5 on the side further away from the opening end 5c than the mouth portion 5. The body portion 6 has a larger outer diameter than the mouth portion 5 (in this specification, "outer diameter" means the equivalent diameter of a circle if the cross-section is not circular). The body portion 6 is cylindrical, and the bottom portion 7 is provided at the lower end of the body portion 6, closing the lower end of the body portion 6. The body portion 6 has a shoulder portion 6b whose outer diameter increases as it moves away from the mouth portion 5. The body portion 6 also has a body body 6c on the bottom 7 side of the shoulder portion 6b. The body body 6c has a shape in which the outer diameter is substantially constant toward the bottom 7, or a shape in which the diameter decreases toward the bottom 7.

[0023] As shown in Figure 4, the container body 2 comprises an inner bag 4 and an outer shell 3 positioned to cover the inner bag 4. The inner bag 4 has its body 4d, excluding the protruding portion 4c, housed within the outer shell 3. In the following description, the parts of the inner bag 4 corresponding 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.

[0024] The average wall thickness of the outer shell 3 at the center of the height direction of the body 6 is, for example, 200 to 800 μm, with a preferred wall thickness of 250 to 500 μm. Specifically, this wall thickness is, for example, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, and 800 μm, and may be within the range of any two of the values ​​exemplified here.

[0025] The average wall thickness of the inner bag 4 at the center of the height direction of the body 6 is, for example, 50 to 250 μm, and preferably 50 to 100 μm. Specifically, this wall thickness is, for example, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, and 250 μm, and may be within the range between any two of the values ​​exemplified herein or less than or equal to either of them. In this specification, the average wall thickness at a predetermined height position means the average value of the measurements taken at eight measurement points set at equal intervals in the circumferential direction at that height position.

[0026] If the mouth attachment member 8 is not equipped with a check valve, the inner bag 4 will not contract after the contents of the inner bag 4 have been discharged, making it difficult to pull out the inner bag 4 through the mouth 5 of the outer shell 3. The present invention makes it easy to pull out the inner bag 4 through the mouth 5 of the outer shell 3, and therefore the significance of applying the present invention is particularly evident when the mouth attachment member 8 is not equipped with a check valve.

[0027] The inner diameter of the opening 5 of the outer shell 3 is, for example, 20 to 50 mm, and preferably 25 to 40 mm. Specifically, the inner diameter of the opening 5 of the outer shell 3 is, for example, 20, 25, 30, 35, 40, 45, 50 mm, and may be within the range of any two of the values ​​exemplified here. The length of the opening 5 is, for example, 15 to 45 mm, specifically, for example, 15, 20, 25, 30, 35, 40, 45 mm, and may be within the range of any two of the values ​​exemplified here.

[0028] <Detailed structure of outer shell 3 and inner bag 4> As shown in Figures 3 and 4, the inner bag 4 is provided with a protruding portion 4c that extends from the open end 3a of the outer shell 3. The protruding portion 4c comprises a protruding cylinder 4c1, an engaging projection 4c2, an annular projection 4c5, and a contact flange 4c4.

[0029] The annular projection 4c5 engages with the mouth attachment member 8 in the axial direction. The engaging projection 4c2 engages with the mouth attachment member 8 in the circumferential direction. In this specification, "axial direction" refers to the direction in which the central axis C of the mouth 5 extends, or in other words, the direction in which the inner bag 4 is pulled out from the container body 2. "Circumferential direction" refers to the direction in which the mouth 5 rotates around the central axis C, or in other words, the direction in which the inner bag 4 rotates relative to the outer shell 3 at the mouth 5.

[0030] It is preferable that the engaging projections 4c2 are provided at multiple locations (eight locations in this embodiment) spaced apart in the circumferential direction. The engaging projections 4c2 are positioned on the annular projection 4c5 and are provided so as to protrude radially outward from the annular projection 4c5. Tapered surfaces 4c8 and 4c3 are provided on the upper surfaces of the annular projection 4c5 and the engaging projection 4c2. This makes it easier for the annular projection 28c (shown in Figure 7A) of the mouth mounting member 8 to overcome the annular projection 4c5 and the engaging projection 4c2, as will be described later.

[0031] Furthermore, as shown in Figure 7A, the lower surface 4c6 of the engaging projection 4c2 is either flush with the lower surface 4c7 of the annular projection 4c5, or is positioned closer to the opening end of the inner bag 4 than the lower surface 4c7 of the annular projection 4c5. With this configuration, the axial engagement between the annular projection 4c5 and the mouth attachment member 8 is reinforced by the engaging projection 4c2, thus strengthening the engagement between the mouth attachment member 8 and the inner bag 4.

[0032] The contact flange 4c4 is positioned to contact the open end 3a and is an annular portion with a larger diameter than the protruding cylinder 4c1. The contact of the contact flange 4c4 with the open end 3a prevents the inner bag 4 from falling into the outer shell 3.

[0033] As shown in Figure 4, the outer circumferential surface of the inner bag body 4d is provided with a cam projection 4g and an engaging projection 4h. The engaging projection 4h is provided on the cam projection 4g. The lower surfaces of the cam projection 4g and the engaging projection 4h are inclined such that, when viewed from the opening end 5c side of the mouth 5, they approach the opening end 5c as one moves counterclockwise.

[0034] As shown in Figure 5, the inner circumferential surface of the outer shell 3 is provided with a cam rail 3l, an engagement recess 3m, and an engagement projection 3n. The engagement recess 3m is provided such that its lower surface is continuous with the upper surface of the cam rail 3l. The upper surface of the cam rail 3l and the lower surface of the engagement recess 3m are inclined so that, when viewed from the opening end 3a side, they approach the opening end 3a as one moves counterclockwise. The engagement projection 3n is positioned adjacent to the engagement recess 3m.

[0035] Before the inner bag 4 is removed from the container body 2, the engaging projection 4h is positioned within the engaging recess 3m, and the lower surface of the cam projection 4g is in contact with the upper surface of the cam rail 3l. The cam projection 4g and the cam rail 3l constitute the cam mechanism 31. In this embodiment, the engaging recess 3m is a through hole, but it may also be a non-through hole.

[0036] When attempting to rotate the inner bag 4 counterclockwise, the engaging projection 4h comes into contact with the engaging projection 3n, restricting rotation. This restriction is not strong; if a strong torque (a torque greater than or equal to the inner plug rotation torque T2 described later) is applied to the inner bag 4, the engaging projection 4h overcomes the engaging projection 3n, allowing the inner bag 4 to rotate freely relative to the outer shell 3. When the inner bag 4 is further rotated counterclockwise, the inner bag 4 moves in a direction that allows it to detach from the container body 2 due to the action of the cam mechanism 31. At this time, the inner bag 4 is twisted and its diameter is reduced.

[0037] An enlarged diameter structure 4k is provided at the opening end 4l of the inner bag 4. The enlarged diameter structure 4k increases the rigidity of the mouth portion 5 of the inner bag 4, suppressing deformation of the mouth portion 5 of the inner bag 4. In this embodiment, the inner bag 4 is pulled out using the engaging portion 4m (more specifically, the annular projection 4c5 and the engaging projection 4c2) provided on the inner bag 4, so a high load may be applied to the inner bag 4. In such cases, if the opening end 4l of the inner bag 4 is easily deformed, it may become difficult to pull out the inner bag 4. However, in this embodiment, deformation of the opening end 4l of the inner bag 4 is suppressed, so the inner bag 4 can be pulled out smoothly.

[0038] <Removal of inner bag 4 by simple operation> The mouth attachment member 8 is configured to be attached to the mouth 5 of the container body 2 by a stoppering mechanism. By placing the mouth attachment member 8 over the mouth 5 and pressing it toward the bottom 7, the mouth attachment member 8 can be engaged with and attached to the mouth 5. The stoppering mechanism of the mouth attachment member 8 has the advantage of simplifying the attachment process of the mouth attachment member 8 in the content filling line, as it can be attached simply by pressing.

[0039] Incidentally, the stopper-type mouth attachment member generally has a separation band that can be separated from the inner stopper, and is configured to be attached to the container body by engaging the engaging portion of the separation band with the engaging portion of the outer shell. When removing the mouth attachment member from the mouth, the first step is to tear the connecting portion between the inner stopper and the separation band to remove the separation band, thereby weakening the engagement force between the mouth attachment member and the outer shell (usually releasing the engagement), and then the mouth attachment member is removed from the mouth. However, it is cumbersome to weaken the engagement force between the mouth attachment member and the outer shell before removing the mouth attachment member from the mouth. The operation to weaken the engagement force could be, for example, by making a cut in the separation band without removing the separation band, thereby weakening the engagement force between the separation band and the outer shell.

[0040] In this embodiment, to solve these problems, the mouth attachment member 8 is configured to move in a direction that allows the inner bag 4 to detach from the container body 2 (i.e., the inner bag 4 to float) by rotating the mouth attachment member 8 relative to the outer shell 3. Furthermore, it is possible to rotate the mouth attachment member 8 relative to the outer shell 3 without performing any operation to weaken the engagement force between the mouth attachment member 8 and the outer shell 3 before rotating the mouth attachment member 8 relative to the container body 2. In other words, the mouth attachment member 8 can be rotated while maintaining the engagement relationship between the mouth attachment member 8 and the outer shell 3 as it was when the mouth attachment member 8 was attached to the mouth 5 of the container body 2.

[0041] More specifically, the mouth attachment member 8 is a stopper type and is engaged with the mouth 5 of the inner bag 4 in the circumferential and axial directions, and is configured so that the inner bag 4 rotates relative to the outer shell 3 as the mouth attachment member 8 rotates. Furthermore, a cam mechanism 31 provided between the inner bag 4 and the outer shell 3 is configured so that the inner bag 4 moves in a direction that allows it to detach from the container body 2 as it rotates.

[0042] With this configuration, the inner bag 4 can be moved away from the container body 2 simply by rotating the mouth attachment member 8, without having to perform troublesome operations such as removing the separation band beforehand. After that, the inner bag 4 can be pulled out of the container body 2 by pulling the mouth attachment member 8. In other words, the inner bag 4 can be pulled out simply by rotating and pulling the mouth attachment member 8, making the operation required to pull out the inner bag 4 very simple. Preferably, the rotation of the mouth attachment member 8 in this case is in the direction of loosening a standard screw (i.e., counterclockwise when viewed from the top of the double container 1). In this case, there is the advantage that it is easy to intuitively understand that the inner bag 4 is moving away from the container body 2.

[0043] Furthermore, since the body 6 of the container body 2 has a larger outer diameter than the opening 5, simply pulling the inner bag 4 will not easily allow it to pass through the opening 5 of the outer shell 3. However, by rotating the opening 5 of the inner bag 4 and twisting the inner bag 4, the body 6 of the inner bag 4 will be able to pass through the opening 5 of the outer shell 3 more easily, allowing the inner bag 4 to be easily pulled out of the container body 2.

[0044] <Detailed structure of the mouth attachment member 8> As shown in Figure 2, in this embodiment, the mouth attachment member 8 is a cap 8a, comprising an inner stopper 26 and an overcap 27. The inner stopper 26 is a press-fit type and is engaged with the mouth 5 of the inner bag 4 in the circumferential and axial directions. The overcap 27 is screwed onto the inner stopper 26.

[0045] As shown in Figures 2, 6, and 8, the overcap 27 comprises an outer cylinder 27a, an intermediate cylinder 27b, an inner cylinder 27c, and a top plate 27d.

[0046] The outer circumferential surface of the outer cylinder 27a is provided with knurling 27e, making it easier to grip and rotate the overcap 27. The inner circumferential surface of the outer cylinder 27a is provided with a female threaded portion 27f. The top plate 27d is provided on the upper surface of the outer cylinder 27a. The lower surface of the top plate 27d is provided with an intermediate cylinder 27b and an inner cylinder 27c. The intermediate cylinder 27b has a smaller diameter than the outer cylinder 27a and is a so-called inner ring positioned inside the outer cylinder 27a. The inner cylinder 27c has a smaller diameter than the intermediate cylinder 27b and is positioned inside the intermediate cylinder 27b.

[0047] As shown in Figures 2 and 6 to 8, the stopper 26 comprises a main body 28 and an opening portion 32. The main body 28 and the opening portion 32 are connected to each other via an easily tearable connecting portion 30.

[0048] The main body 28 comprises an outer cylinder 28a, an inner cylinder 28b, an annular projection 28c, an engaging projection 28d, a top plate 28e, a discharge cylinder 28f, and a mounting cylinder 28g. The opening portion 32 and the connecting portion 30 are located inside the discharge cylinder 28f and the inner cylinder 28b. The opening portion 32 is provided with an engaging cylinder 32a having an engaging portion (not shown), and the inner cylinder 27c and the engaging cylinder 32a are engaged in the circumferential and axial directions. With this configuration, by rotating the overcap 27 relative to the main body 28, the engaging cylinder 32a can be rotated relative to the main body, making it possible to break the connecting portion 30. By breaking the connecting portion 30, the opening portion 32 is separated from the main body 28, and a flow hole is formed inside the discharge cylinder 28f and the inner cylinder 28b. The contents of the inner bag 4 can be discharged through this flow hole.

[0049] The outer surface of the outer cylinder 27a is provided with knurling 28i, making it easier to grip and rotate the inner stopper 26. The top plate 28e is provided on the upper surface of the outer cylinder 28a. The inner cylinder 28b is provided on the lower surface of the top plate 28e. The inner cylinder 28b has a smaller diameter than the outer cylinder 28a and is a so-called inner ring positioned inside the outer cylinder 28a. When the inner stopper 26 is attached to the opening 5, the inner cylinder 28b is inserted into the inner bag 4, and the outer surface of the inner cylinder 28b comes into close contact with the inner surface of the inner bag 4.

[0050] A discharge tube 28f and a mounting tube 28g are provided on the upper surface of the top plate 28e. The contents of the inner bag 4 are discharged through the discharge tube 28f. As shown in Figure 2, a male threaded portion 28h is provided on the outer circumference of the mounting tube 28g, and the overcap 27 is screwed onto the inner plug 26 by the male threaded portion 28h engaging with a female threaded portion 27f provided on the inner circumference of the outer cylinder 27a of the overcap 27. In this case, the overcap 27 can be attached to and detached from the inner plug 26 by rotating the overcap 27 relative to the inner plug 26. When the overcap 27 is attached to the inner plug 26, the intermediate tube 27b is inserted into the discharge tube 28f, and the outer circumference of the intermediate tube 27b is in close contact with the inner circumference of the discharge tube 28f. The upper side of the discharge tube 28f is closed by the overcap 27.

[0051] The annular projection 28c is an annular projection provided on the inner circumferential surface of the outer cylinder 28a so as to extend in the circumferential direction. The annular projection 28c engages with the engaging projection 4c2 in the axial direction, thereby causing the main body 28 to engage with the opening 5 of the inner bag 4 in the axial direction. It is preferable that the engaging projections 28d are provided at multiple locations (eight locations in this embodiment) spaced apart in the circumferential direction. The engaging projections 28d are positioned on the annular projection 28c and are provided so as to protrude radially inward from the annular projection 28c. The engaging projections 28d are positioned between adjacent engaging projections 4c2, thereby causing the main body 28 to engage with the opening 5 of the inner bag 4 in the circumferential direction.

[0052] <Rotational direction and torque of overcap 27 and inner plug 26> The overcap 27 is preferably screwed onto the inner stopper 26 by a right-hand thread. Therefore, the screw connection between the overcap 27 and the inner stopper 26 can be released by rotating the overcap 27 in the right-hand thread loosening direction relative to the inner stopper 26. Also, by rotating the inner stopper 26 in the right-hand thread loosening direction relative to the outer shell 3, the inner bag 4 moves in a direction that allows it to detach from the container body 2. In this way, the overcap 27 can be removed by rotating the overcap 27 in the right-hand thread loosening direction, and the inner bag 4 can be lifted up by rotating the inner stopper 26 in the right-hand thread loosening direction. Since both operations are performed in the same rotational direction, there is an advantage in that the operation is simple.

[0053] On the other hand, in the above configuration, if the container body 2 and the overcap 27 are grasped and the overcap 27 is rotated in the direction of loosening the right-hand thread, the overcap 27 does not rotate relative to the inner stopper 26, but rather the overcap 27 and the inner stopper 26 rotate together relative to the container body 2, and as a result there is a risk that the inner bag 4 will float up.

[0054] To suppress the occurrence of such problems, in this embodiment, if T1 is the rotational torque of the overcap 27 required to first rotate the overcap 27 in the right-hand thread loosening direction relative to the inner plug 26, and T2 is the rotational torque of the inner plug 26 required to first rotate the inner plug 26 in the right-hand thread loosening direction relative to the outer shell 3, then it is preferable that T2 / T1 is 1.2 or more. By applying a torque of T1 or more to the overcap 27, the overcap 27 can be rotated in the loosening direction. By applying a torque of T2 or more to the inner plug 26, the inner plug 26 can be rotated in the loosening direction.

[0055] In this case, if the container body 2 and the overcap 27 are grasped and the overcap 27 is rotated in the direction of loosening the right-hand thread, the overcap 27 rotates relative to the inner stopper 26 before the inner stopper 26 rotates relative to the outer shell 3, thus suppressing the occurrence of the above problem. T2 / T1 is, for example, 1.2 to 5, and preferably 1.5 to 3. Specifically, T2 / T1 is, for example, 1.2, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, and may be within the range of any two of the values ​​exemplified here.

[0056] T1 is, for example, 40 to 120 N·cm, preferably 60 to 100 N·cm. T2 is, for example, 100 to 200 N·cm, preferably 130 to 170 N·cm. Specifically, T1 is, for example, 40, 50, 60, 70, 80, 90, 100, 110, 120 N·cm, and may be within the range between any two of the values ​​exemplified here, or greater than or less than any of them. Specifically, T2 is, for example, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 N·cm, and may be within the range between any two of the values ​​exemplified here, or greater than or less than any of them.

[0057] In this embodiment, the overcap rotation torque T1 is the torque required to break the connecting portion 30 and separate the opening portion 32 from the main body portion 28. In another embodiment, instead of providing the opening portion 32 on the inner plug 26, an opening ring is provided on the overcap 27 via an easily tearable connecting portion, and the opening ring engages with the inner plug 26 in the circumferential direction. In this configuration, the overcap rotation torque T1 is the torque required to break the thin-walled portion and separate the opening ring from the overcap 27. Furthermore, in yet another embodiment, a rotation restricting structure is provided to restrict the rotation of the overcap 27 relative to the inner plug 26, and when the rotation restriction by the rotation restricting structure is released by a predetermined torque (for example, when the rotation is restricted by the contact between the protrusion of the overcap 27 and the protrusion of the inner plug 26, and the rotation restriction is released when the protrusion of the overcap 27 overcomes the protrusion of the inner plug 26), the torque required to release the restriction is the overcap rotation torque T1.

[0058] In this embodiment, the plug rotation torque T2 is the torque required for the engaging projection 4h to overcome the engaging projection 3n. In another embodiment, for example, the plug 26 and the outer shell 3 may be engaged in the circumferential direction, and the engagement may be released when the plug rotation torque T2 is applied.

[0059] Furthermore, if T3 is the overturn torque required to first rotate the stopper 26 in the right-hand thread loosening direction relative to the inner bag 4, then T3 / T2 is preferably 1.2 or greater. This prevents the stopper 26 from spinning freely relative to the inner bag 4. T3 / T2 is, for example, 1.2 to 5, and preferably 1.5 to 3. Specifically, T3 / T2 may be, for example, 1.2, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0, and may be within the range between any two of the values ​​exemplified here, or greater than or equal to either of them.

[0060] T3 is, for example, 200 N·cm or more, preferably 200 to 1000 N·cm, specifically, for example, 200, 250, 300, 350, 400, 500, and 1000 N·cm, and may be within the range of any two of the values ​​exemplified here. In this embodiment, the overturn torque T3 is the torque required for the engaging projection 28d to overcome the engaging projection 4c2.

[0061] <Preventing operational errors using shrink film> By the way, there is a risk that when intending to grasp and rotate the overcap 27, one might accidentally grasp and rotate the inner stopper 26 instead. In this case, there is a risk that the inner bag 4 will twist as the inner stopper 26 rotates, causing the contents to spill out.

[0062] In this embodiment, as shown in Figure 9, a shrink film 33 is used to suppress the occurrence of such problems. In this embodiment, before opening, the shrink film 33 covers the container body 2, the inner stopper 26, and the overcap 27. The shrink film 33 is provided with easy-cut lines 33a and 33b. The easy-cut lines 33a and 33b are lines that facilitate cutting the shrink film, such as perforations or half-cut lines. The easy-cut line 33a is provided at the boundary between the inner stopper 26 and the overcap 27, or at a position facing the inner stopper 26, so as to extend in the circumferential direction of the inner stopper 26. If a part of the shrink film 33 (i.e., the upper part 33c above the easy-cut line 33a) is removed along such an easy-cut line 33a, the shrink film 33 becomes a covering that covers the inner stopper 26 but not the overcap 27. In this state, it is difficult to grip and rotate the inner stopper 26, thus suppressing the erroneous operation of accidentally rotating the inner stopper 26. Alternatively, instead of providing an easy-cut line 33a, the shrink film 33 may be attached so that its upper edge is positioned at the boundary between the inner plug 26 and the overcap 27, or opposite the inner plug 26. In this case, a covering state is achieved where the inner plug 26 is covered but the overcap 27 is not, before removing a portion of the shrink film 33.

[0063] Furthermore, the easy-cut line 33b is provided to facilitate the removal of the lower portion 33d of the shrink film 33 that is below the easy-cut line 33a. The easy-cut line 33b is preferably provided non-parallel to the easy-cut line 33a and perpendicular to the easy-cut line 33a. It is also preferable that the easy-cut line 33b is connected to the easy-cut line 33a and reaches the lower edge of the lower portion 33d.

[0064] Furthermore, the method of preventing accidental operation using shrink film is also applicable when the cap 8a is not of the snap-on type. When the cap 8a is screw-on, the cap 8a is attached to the container body 2 by screwing it onto the opening of the outer shell 3. In addition, the method of preventing accidental operation using shrink film is also applicable when the overcap is not screwed on but engages with the inner stopper 26 by, for example, a snap engagement. Moreover, it is also applicable when the inner bag 4 is raised by rotating the inner stopper 26 in the reverse thread loosening direction.

[0065] <Shape of container body 2> In this embodiment, as shown in Figures 2 and 10-12, the container body 2 has a roughly rectangular cross-section (a rectangular shape with rounded corners) as the shape of the body 6 approaches the bottom 7. More specifically, at the upper end of the shoulder 6b, the cross-section is circular as shown in Figure 12A, at the body 6c, the cross-section is roughly rectangular as shown in Figure 12C, and in the middle of the shoulder 6b, the cross-section is a shape between circular and roughly rectangular as shown in Figure 2B. In other words, at the shoulder 6b, the container body 2 expands in diameter towards the bottom 7, and its shape gradually approaches a roughly rectangular cross-section. Furthermore, a recess 7a is provided at the bottom 7.

[0066] Figure 12C shows a cross-section P of the container body 2 at a position 0.2J from the bottom surface, where J is the total height of the container body 2. In cross-section P, the container body 2 has three or more corners 2a spaced apart in the circumferential direction, and connecting portions 2b with a radius of curvature greater than that of the corners 2a are provided between the corners 2a. The inner bag 4 has the same shape as the container body 2. Unless otherwise specified, the radius of curvature refers to the value on the outer surface of the container body 2.

[0067] In a container body 2 of this shape, when the inner bag 4 is rotated counterclockwise relative to the outer shell 3, the connecting portion 2b rotates more easily than the corner portion 2a, so as shown in Figure 13, a bent shape 2c is easily formed near the boundary between the connecting portion 2b and the corner portion 2a. If the inner bag 4 is further rotated counterclockwise in this state, the inner bag 4 is reduced in diameter so that the corner portion 2a of the inner bag 4 folds, making it easier to pull out the inner bag 4. In this embodiment, there are four corner portions 2a, but the same effect is obtained even if there are three corner portions 2a or five or more. The number of corner portions 2a is, for example, 3 to 12, and 3 to 6 is preferred.

[0068] In cross-section P, if the length of the longest connecting portion 2b is L1 and the length of the shortest connecting portion 2b is L2, then it is preferable that the value of [(L1-L2) / L1] is 0.1 or less. In this case, the lengths of all connecting portions 2b are approximately the same, and the cross-section becomes a roughly regular polygon. In this case, the connecting portions 2b are more easily rotated, so the corners 2a of the inner bag 4 are more easily folded.

[0069] In cross-section P, if R1 is the radius of curvature at the point where the radius of curvature is smallest at corner 2a, and R2 is the radius of curvature at the point where the radius of curvature is largest at connecting portion 2b, then R2 / R1 is preferably 3 or greater. In this case, the corner 2a of the inner bag 4 becomes even easier to fold. The connecting portion 2b may be a flat surface, in which case the radius of curvature is infinite. The corner 2a is preferably convex toward the outside of the container body 2. The connecting portion 2b may be convex toward the outside, flat, or convex toward the inside. R2 / R1 is, for example, 3 to 1000, specifically, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 100, 500, 1000, and may be within the range between any two of the values ​​exemplified here, or greater than or equal to either of them.

[0070] The radius of curvature R1 is, for example, 5 to 20 mm, specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 mm, and may be within the range of any two of the values ​​exemplified here. The radius of curvature R2 is, for example, 30 mm or more, preferably 30 to 200 mm, specifically, for example, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 mm, and may be within the range of any two of the values ​​exemplified here or greater than or equal to either of them. If R3 is the equivalent radius of the circle of the container body 2 at cross-section P, then R1 / R3 is, for example, 0.2 to 0.6, specifically, for example, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, and may be within the range of any two of the values ​​exemplified here. The equivalent radius R3 is, for example, 15 to 40 mm, specifically, for example, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 mm, and may be within the range of any two of the values ​​exemplified here.

[0071] In cross-section P, if T1 is the thickness of the inner bag 4 at the corner 2a where the wall thickness is minimum, and T2 is the thickness of the inner bag 4 at the connecting portion 2b where the wall thickness is maximum, then T1 / T2 is preferably 0.90 or less. In cross-section P, if T1a is the average value of the wall thickness of the inner bag 4 at all corners 2a, and T2a is the average value of the wall thickness of the inner bag 4 at all connecting portions 2b, then T1a / T2a is preferably 0.90 or less. In this case, the corners 2a of the inner bag 4 become even easier to fold. T1 / T2 or T1a / T2a are, for example, 0.40 to 0.90, specifically, for example, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, and 0.90, and may be within the range of any two of the values ​​exemplified here. T1 and T1a are preferably 95 μm or less. T1 and T1a are, for example, 50 to 95 μm, specifically, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, and 95 μm, and may be within the range of any two of the values ​​exemplified here or less. T2 and T2a are, for example, 60 to 150 μm, specifically 60, 70, 80, 90, 100, 110, 120, 130, 140, and 150 μm, and may also be within the range of any two of the values ​​exemplified here.

[0072] <Method for dispensing contents from double container 1> As described above, in the double-walled container 1 of this embodiment, the inner bag 4 can be pulled out from the container body 2 using the mouth attachment member 8. As shown in Figure 14, the mouth attachment member 8 remains engaged with the inner bag 4 after it has been pulled out.

[0073] If the mouth attachment member 8 is a cap 8a, the inner bag 4 can be pulled out from the container body 2 with some of the contents remaining inside the inner bag 4 (pulling step), and then the contents remaining inside the inner bag 4 can be discharged (discharge step).

[0074] Since the inner bag 4 is more flexible than the outer shell 3, the contents can be easily dispensed by squeezing or compressing the inner bag 4, and the amount of residue (hereinafter referred to as "final residue") can be reduced when further dispensing is no longer possible.

[0075] The final residual amount generally tends to increase with increasing viscosity, but according to the method of this embodiment, even at high viscosity, the increase in the final residual amount can be suppressed. Therefore, the technical significance of the method of this embodiment is particularly pronounced when the contents have high viscosity (for example, 100 mPa·s or more). The viscosity of the contents is, for example, 100 to 10000 mPa·s, specifically, for example, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, and 10000 mPa·s, and may be within the range between any two of the values ​​exemplified here, or greater than or equal to either of them.

[0076] Incidentally, as shown in Figure 10, a frustoconical recess 7a is provided at the bottom 7 of the container body 2. The recess 7a is also provided at the bottom 7 of the inner bag 4. Since the frustoconical recess 7a has a circular cross-section (a cross-section perpendicular to the central axis C), it is difficult to deform, and if a frustoconical recess 7a is present in the inner bag 4, there is a risk that the reduction of the final residual amount will be insufficient. From this viewpoint, it is preferable to provide a recess with a flattened cross-section at the bottom of the container body 2. Since such a recess is easier to deform than a recess with a circular cross-section, the final residual amount can be further reduced.

[0077] Furthermore, if the engagement force between the inner bag 4 and the cap 8a is weak, there is a risk that the cap 8a may detach from the inner bag 4 after the inner bag 4 is pulled out, causing the contents to leak out. On the other hand, in this embodiment, the axial engagement between the annular projection 4c5 and the mouth attachment member 8 is reinforced by the engagement projection 4c2, so that the engagement between the cap 8a and the inner bag 4 is strengthened, and the detachment of the cap 8a from the inner bag 4 is suppressed.

[0078] <Thickness of inner bag 4> The inner bag 4 is preferably thin. This is because the thinner the inner bag 4 is, the more flexible it becomes, making it easier to reduce the final residue amount and allowing for a reduction in the amount of resin used.

[0079] From this perspective, it is preferable that the inner bag 4 has a thin-walled portion with a wall thickness of 100 μm or less. Furthermore, it is preferable that the thin-walled portion be located closer to the bottom than the center in the height direction of the body portion 6. The wall thickness of the thin-walled portion is preferably 95 μm or less, more preferably 90 μm or less, for example, 50 to 100 μm, specifically for example 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 μm, and may be within the range of any two of the values ​​exemplified here.

[0080] <Layer structure of inner bag 4> The inner bag 4 may be a single-layer or multi-layer structure. As shown in Figure 15, it is preferable that the inner bag 4 comprises, in order from the inside out, an inner layer 4i, a gas barrier layer 4j, and an outer layer 4e.

[0081] The inner layer 4i is positioned inside the inner bag 4, beyond the gas barrier layer 4j. By having the inner layer 4i in the inner bag 4, the gas barrier layer 4j is prevented from being exposed to moisture contained in the contents.

[0082] The thickness of the inner layer 4i is, for example, 5 to 60 μm, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 μm, and may be within the range of any two of the values ​​exemplified here. Preferably, the inner layer 4i comprises, in order from the inside of the inner bag 4, an innermost layer 4i1, a reproduction layer 4i2, and an adhesive layer 4i3.

[0083] The innermost layer 4i1 is preferably made of a resin with excellent moisture barrier properties, such as polyolefin (e.g., polyethylene, polypropylene) or PET. The innermost layer 4i1 is the layer that comes into contact with the contents inside the inner bag 4, and in order to suppress contamination of the contents, it is preferable to make it of new resin (hereinafter referred to as "virgin resin") rather than recycled resin.

[0084] The repro layer 4i2 is preferably composed of a resin containing recycled resin, and more preferably a mixed resin composed of recycled resin and virgin resin. By providing the repro layer 4i2, environmental impact and container manufacturing costs can be reduced. The repro layer 4i2 can be omitted if it is not needed.

[0085] When the total mass of the mixed resin is considered to be 100%, the mixed resin preferably contains 15-50% by mass of recycled resin (15, 20, 25, 30, 35, 40, 45, 50%) and 50-85% by mass of virgin resin (50, 55, 60, 65, 70, 75, 80, 85%). The ratio of recycled resin to virgin resin may be within the range of any two of the numerical values ​​exemplified in parentheses. The recycled resin is a resin obtained by recycling scrap generated during the molding of the container body 2. Since the scrap contains all the layers of the container body 2, the recycled resin is a mixture of the resin compositions that make up each of the layers of the container body 2.

[0086] The adhesive layer 4i3 is composed of an adhesive resin. Examples of adhesive resins include acid-modified polyolefin resins (e.g., maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene). By providing the adhesive layer 4i3, the adhesion between layers adjacent to the adhesive layer 4i3 is improved.

[0087] The outer layer 4e is positioned outside the inner bag 4, beyond the gas barrier layer 4j. By having the outer layer 4e in the inner bag 4, the gas barrier layer 4j is prevented from being exposed to moisture contained in the outside air.

[0088] The thickness of the outer layer 4e is, for example, 5 to 60 μm, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 μm, and may be within the range of any two of the values ​​exemplified here. Preferably, the outer layer 4e comprises, in order from the outside of the inner bag 4, an outermost layer 4e1 and an adhesive layer 4e2.

[0089] The outermost layer 4e1 is preferably made of a resin with excellent moisture barrier properties, such as polyolefin (e.g., polyethylene, polypropylene) or PET. The outermost layer 4e1 is a layer exposed to the outside of the inner bag 4, and is preferably made of virgin resin in order to suppress contamination from the external environment.

[0090] The description of adhesive layer 4e2 is the same as that of adhesive layer 4i3.

[0091] The value of (thickness of inner layer 4i / thickness of outer layer 4e) is preferably, for example, 0.2 to 5. Specifically, this value is, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.5, 4.0, 4.5, 5.0, and may be within the range of any two of the values ​​exemplified here.

[0092] If the inner layer 4i is thicker than the outer layer 4e, the gas barrier layer 4j can be more reliably protected from moisture in the contents. If the outer layer 4e is thicker than the inner layer 4i, the gas barrier layer 4j can be more reliably protected from external moisture.

[0093] In this embodiment, the thickness of the inner layer 4i is made greater than that of the outer layer 4e, and the reproduction layer 4i2 is placed on the inner layer 4i, which makes it possible to make the thickness of the reproduction layer 4i2 relatively large. However, the reproduction layer 4i2 may be provided on both the inner layer 4i and the outer layer 4e, or it may be provided only on the outer layer 4e. Furthermore, the reproduction layer 4i2 may contain materials that may contain components that have a strong odor or component migration to the contents, such as post-consumer materials. In this case, it is preferable to place the reproduction layer 4i2 on the outer layer 4e in order to suppress the migration of odor and components from the reproduction layer 4i2 to the contents. In this case, the thickness of the outer layer 4e may be made greater than that of the inner layer 4i, so that the amount of resin used in the reproduction layer 4i2 is increased.

[0094] The gas barrier layer 4j is composed of a gas barrier resin. In this specification, the gas barrier resin, in the form of a 20 μm thick film, has an oxygen permeability of 50 cc / (m²) in an environment of 20°C and 65% RH. 2 This means less than 24 hours (atm). The above oxygen permeability is, for example, 0-49 cc / (m³). 2 ·24 hours·atm), specifically for example 0.01, 0.1, 0.2, 0.5, 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 49 cc / (m 2 The hours are 24 hours (atm), and may be within the range between any two of the values ​​exemplified here, or less than or equal to any two of them.

[0095] The gas barrier resin preferably has a value of (oxygen permeability under conditions of 20°C and 100% RH) / (oxygen permeability under conditions of 20°C and 40% RH) of 2 or more, and more preferably 5 or more. A larger value indicates lower gas barrier properties under high humidity, highlighting the significant technical importance of applying the present invention. This value is, for example, between 2 and 10000, specifically, for example, 2, 5, 10, 20, 50, 100, 200, 1000, and 10000, and may be within the range of any two of the values ​​exemplified here, or greater than or equal to either of them.

[0096] The gas barrier resin may consist solely of resins with high gas barrier properties, such as EVOH or polyamide, or it may be a mixed resin of the above resin with another resin. An example of another resin is an adhesive resin. By incorporating an adhesive resin into the gas barrier layer 4j, the adhesive layers 4i3 and 4e2 can be omitted, thereby reducing the number of layers constituting the inner bag 4.

[0097] The thickness of the gas barrier layer 4j is, for example, 20 to 100 μm, specifically, for example, 20, 30, 40, 50, 60, 70, 80, 90, and 100 μm, and may be within the range of any two of the values ​​exemplified here.

[0098] 1-2. Manufacturing method of double-walled container 1 As shown in Figures 16 to 18, the container body 2 can be formed by heating the preform 15 and biaxially stretched blow molding it.

[0099] <Composition: Inner preform 14, outer preform 13, preform 15> In one example, the preform 15 can be constructed by covering an inner preform 14, which will become the inner bag 4, with an outer preform 13, which will become the outer shell 3.

[0100] As shown in Figure 16, the inner preform 14 is a bottomed cylindrical shape and comprises a mouth portion 14a, a body portion 14b, and a bottom portion 14c. A projection 14d is provided at the open end of the mouth portion 14a. The projection 14d remains unchanged in shape during molding and becomes the projection 4c. Therefore, the matters described for the projection 4c also apply to the projection 14d. An engaging portion 14m is provided on the projection 14d. The engaging portion 14m becomes the engaging portion 4m after molding and is used to pull out the inner bag 4. The bottom portion 14c is provided to close the lower end of the body portion 14b. A positioning pin (not shown) may be provided on the bottom portion 14c.

[0101] As shown in Figure 16, the outer preform 13 is a bottomed cylindrical shape and comprises a mouth portion 13a, a body portion 13b, and a bottom portion 13c. The bottom portion 13c is provided to close the lower end of the body portion 13b. The bottom portion 13c is provided with an annular projection 13d and a positioning hole (not shown).

[0102] As shown in Figure 18, a preform 15 can be formed by placing an outer preform 13 over an inner preform 14. If the inner preform 14 is provided with positioning pins, these positioning pins can be inserted into positioning holes in the outer preform 13 to position the inner preform 14 and the outer preform 13 relative to each other. In the preform 15, the openings 14a and 13a face each other, and the body portions 14b and 13b face each other.

[0103] The openings 13a and 14a become the opening 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. The body portion 15b and the bottom portion 15c are mainly stretched in biaxial stretch blow molding.

[0104] <Materials and manufacturing method of inner preform 14 and outer preform 13> The inner preform 14 and outer preform 13 can be formed by direct blow molding or injection molding of thermoplastic resins such as polyester (e.g., PET) or polyolefin (e.g., polypropylene, polyethylene). In one example, the inner preform 14 is made of polyolefin (e.g., polypropylene), and the outer preform 13 is made of PET. Polypropylene is preferred over polyethylene as the polyolefin used in the inner preform 14 because its temperature for biaxially oriented blow molding is closer to that of PET than that of polyethylene.

[0105] <Manufacturing of internal preform 14 by direct blow molding> The inner preform 14 is preferably formed by direct blow molding using a molten cylindrical parison. Direct blow molding makes it easier to thin the wall compared to injection molding, so forming the inner preform 14 by direct blow molding makes it possible to thin the wall of the inner bag 4. Furthermore, in order to form a multilayer inner bag 4, it is desirable that the inner preform 14 be configured to have an inner layer 14i, a gas barrier layer 14j, and an outer layer 14e in order from the inside, as shown in Figure 23. However, an inner preform 14 with such a configuration is not easy to form by multilayer injection molding. In addition, if a gate is provided at the bottom 14c of the inner preform 14, for example, the resin constituting the gas barrier layer 14j may not reach the opening end of the inner preform 14, which could lead to a decrease in gas barrier properties. In particular, the smaller the wall thickness of the inner preform 14, the less the resin flows, and the more pronounced the above problem becomes. On the other hand, in direct blow molding, a cylindrical parison is used which has a configuration corresponding to an inner layer 14i, a gas barrier layer 14j, and an outer layer 14e, making it easy to provide the gas barrier layer 14j over the entire inner preform 14.

[0106] Direct blow molding can be performed by placing a molten cylindrical parison 34 between open split molds 35 and 36, as shown in Figure 19, and then closing the split molds 35 and 36, as shown in Figure 20, to form a bag-shaped parison. Air is then blown into the bag-shaped parison to form the shape along the shaping surfaces of the split molds 35 and 36. Direct blow molding forms a molded body 38 with burrs 39. After this, the molded body 38 is removed from the split molds 35 and 36, and the burrs 39 are removed to obtain the molded body 38 shown in Figure 21.

[0107] The molded body 38 has a shape in which a bag portion 40 is connected to the open end 14o of the inner preform 14. An annular recess 41 indicating a cut portion is provided at the boundary between the inner preform 14 and the bag portion 40.

[0108] Next, as shown in Figure 22, the molded body 38 is cut along the annular recess 41 and the bag portion 40 is removed to obtain the inner preform 14. The annular recess 41 is a recess on the outside of the molded body 38, but it is an annular protrusion 41a on the inside of the molded body 38. When the molded body 38 is cut along the annular recess 41, the annular protrusion 41a may partially remain, resulting in a burr 14p protruding inward toward the inside of the inner preform 14, as shown in Figure 22C. Alternatively, even if the annular protrusion 41a is not formed on the inside of the molded body 38, a burr 14p may be formed during cutting. If an expanding structure 14l is not provided at the open end 14o of the inner preform 14, the burr 14p may hinder the tight seal between the outer circumferential surface of the inner cylinder 28b of the inner stopper 26 and the inner circumferential surface of the inner bag 4. However, in this embodiment, the burr 14p is formed in the expanding structure 14l, so the burr 14p does not hinder the tight seal.

[0109] <Relationship between the shape of the inner preform 14 and the outer diameter of the cylindrical parison 34> As shown in Figure 17B, if D1 is the outer diameter of the part of the inner preform 14 where the outer diameter is largest at the mouth 14a (outer diameter at the contact flange 14n), and as shown in Figure 19, if D3 is the outer diameter of the cylindrical parison 34, then it is preferable that D1 / D3 is 1.5 or more. The larger D1 / D3 is, the larger the blow ratio when forming the inner preform 14, so the wall thickness of the mouth 14a of the inner preform 14 tends to be smaller. If the wall thickness of the mouth 14a of the inner preform 14 is small, the rigidity of the mouth 14a decreases, and when cutting the molded body 38 along the annular recess 41, the mouth 14a may deform, making it difficult to cut accurately. On the other hand, in this embodiment, the opening end 14o of the inner preform 14 is provided with an expanding structure 14l that suppresses deformation of the mouth 14a, so deformation of the mouth 14a is suppressed.

[0110] D1 / D3 is preferably 2 or more, and preferably 2.5 or more. D1 / D3 is, for example, 1.5 to 4.0, specifically, for example, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, and may be within the range of any two of the values ​​exemplified here. D1 is, for example, 25 to 40 mm, specifically, for example, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 mm, and may be within the range of any two of the values ​​exemplified here. D3 is, for example, 8-25mm, specifically 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25mm, and may also be within the range of any two of the values ​​exemplified here.

[0111] The inner preform 14 preferably has a wall thickness of 1.5 mm or less at its open end 14o. In this case, the rigidity of the opening 14a of the inner preform 14 and the opening 5 of the inner bag 4 is particularly low, so the technical significance of providing the enlarged diameter structure 14l,4k is remarkable. This wall thickness is, for example, 0.5 to 1.5 mm, specifically, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 mm, and may be within the range of any two of the values ​​exemplified here.

[0112] As shown in Figure 17B, if the total height of the inner preform 14 is H, and the outer diameter of the inner preform 14 at a height position where the height from the bottom 14c of the inner preform 14 is 0.1H is D2, then it is preferable that D2 / D1 is 0.35 or more, and more preferably 0.50 or more. When the split molds 35 and 36 are closed, the cylindrical parison 34 is sandwiched between the pinch-off portions 35a and 36a of the split molds 35 and 36, causing the inner surfaces of the cylindrical parison 34 to weld together and form a seal.

[0113] Since the seal portion is aesthetically unpleasing, it is undesirable for it to be formed on the body portion 14b of the inner preform 14. The larger D2 is, the less likely it is that a seal portion will be formed on the body portion 14b of the inner preform 14, so the outer diameter of the usable cylindrical parison 34 will increase. Also, the smaller D1 is, the smaller the blow ratio at the mouth portion 14a of the inner preform 14, and the thicker the mouth portion 14a becomes. As a result, the rigidity of the mouth portion 5 of the inner bag 4 increases, making it easier to pull out the inner bag 4.

[0114] D2 is, for example, 12 to 30 mm, specifically 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30 mm, and may also be within the range of any two of the values ​​exemplified here.

[0115] Furthermore, it is preferable that D2 / D1 be 0.8 or less. If D2 / D1 is too large, the wall thickness of the body 6 of the inner bag 4 tends to increase, which may result in poor discharge of the contents.

[0116] D2 / D1 is, for example, 0.35 to 1.0, specifically, for example, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, and may also be within the range of any two of the numbers exemplified here.

[0117] D2 / D3 is preferably 1.1 or higher, and more preferably 1.4 or higher. In this case, a seal portion is less likely to form on the body portion 14b of the inner preform 14, and the aesthetic appearance of the inner preform 14 is improved. D2 / D3 is, for example, 1.1 to 2.0, specifically, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, and may be within the range of any two of the values ​​exemplified here.

[0118] <Protruding seal portion 42> The seal portion formed by welding the inner surfaces of the cylindrical parison 34 together may have insufficient strength. Therefore, as shown in Figure 23A, it is preferable to make the seal portion 43 protrude from the main body portion 14q of the inner preform 14 to form a protruding seal portion 42. The protruding seal portion 42 is formed by welding the inner surfaces of the cylindrical parison 34 together and protrudes from the main body portion 14q of the inner preform 14. The main body portion 14q refers to the part of the inner preform 14 other than the protruding seal portion 42. As shown in Figure 23A, by making the seal portion 43 protrude to form a protruding seal portion 42, the area of ​​the sealing surface 43a is increased, and the sealing strength at the seal portion 43 is improved.

[0119] Incidentally, if the inner preform 14 comprises an inner layer 14i, a gas barrier layer 14j, and an outer layer 14e in that order from the inside, as shown in Figure 23A, opposing inner layers 14i are welded to each other at the sealing surface 43a, but the gas barrier layers 14j are not welded to each other, nor are the outer layers 14e. Therefore, a non-barrier region 44 is provided near the sealing portion 43 where the gas barrier layer 14j is not present. The wider the non-barrier region 44, the lower the gas barrier performance against the contents.

[0120] When the outer preform 13 is placed over the inner preform 14 and biaxial stretch blow molding is performed, stretching also occurs in the protruding seal portion 42, resulting in the structure shown in Figure 23B, which widens the non-barrier area 44 and further reduces the gas barrier properties. The inner layer 14i, gas barrier layer 14j, and outer layer 14e of the main body portion 14q of the inner preform 14 correspond to the inner layer 4i, gas barrier layer 4j, and outer layer 4e of the main body portion 4q of the inner bag 4, respectively. Furthermore, in the configurations shown in Figures 23A to 23B, stretching at the seal portion 43 is not suppressed, so forces are applied from both sides of the seal surface 43a in a direction that peels off the seal surface 43a, which may cause the seal surface 43a to peel off.

[0121] To solve these problems, in this embodiment, the protruding seal portion 42 shown in Figure 24A is formed by direct blow molding, and then the protruding seal portion 42 is bent to form a bent structure as shown in Figure 24B. The protruding seal portion 42 can be bent, for example, after being reheated and softened.

[0122] When the outer preform 13 is placed over the inner preform 14 and biaxial stretch blow molding is performed, the bent protruding seal portion 42 suppresses stretching at the seal portion 43. In addition, even if the seal portion 43 is stretched, the non-barrier area 44 does not expand, thus suppressing a decrease in gas barrier properties. Therefore, in this embodiment, the bent protruding seal portion 42 becomes a stretch-suppressing structure that suppresses stretching of the seal portion 43 during biaxial stretch blow molding.

[0123] Preferably, the main body portion 14q is provided with a groove 14r along the protruding seal portion 42. In this case, by bending the protruding seal portion 42 and housing it within the groove 14r, the amount of protrusion of the protruding seal portion 42 from the main body portion 14q is reduced, and the portion corresponding to the protruding seal portion 42 becomes less noticeable even after biaxial stretch blow molding.

[0124] The protruding seal portion 42 is preferably provided with a base portion 42a and an outer portion 42b, in that order from the main body portion 14q side, and the outer portion 42b preferably has a portion with a greater wall thickness than the base portion 42a. With such a configuration, the protruding seal portion 42 is easily bent at the base portion 42a. Furthermore, as shown in Figures 17C to 17D, it is preferable that the protruding seal portion 42 is provided spanning the bottom portion 14c and the body portion 14b of the main body portion 14q. The outer portion 42b is preferably provided with a thick portion 42b1 and a thin portion 42b2 with a smaller wall thickness than the thick portion 42b1, and the thin portion 42b2 is provided at a position adjacent to the boundary between the bottom portion 14c and the body portion 14b. If the thick portion 42b1 is provided at the boundary between the bottom portion 14c and the body portion 14b, the thick portions 42b1 will interfere with each other when trying to bend the protruding seal portion 42, making it difficult to bend the protruding seal portion 42. By providing a thin-walled portion 42b2 at the boundary between the bottom portion 14c and the body portion 14b, the protruding seal portion 42 can be easily bent even when it spans both the bottom portion 14c and the body portion 14b. It is preferable that the thick-walled portion 42b1 has a greater wall thickness than the base portion 42a. It is preferable that the thin-walled portion 42b2 has a smaller wall thickness than the base portion 42a.

[0125] <Surface treatment of internal preform 14> When the inner preform 14 is formed by direct blow molding, it is possible to make the inner preform 14 thinner compared to when the inner preform 14 is formed by injection molding. As a result, it is also possible to make the inner bag 4 thinner, and the inner bag 4 may contain thin-walled portions with a wall thickness of 100 μm or less. The adhesion force between the inner bag 4 and the outer shell 3 tends to be stronger as the wall thickness of the inner bag 4 decreases. In addition, depending on the combination of materials of the inner preform 14 and the outer preform 13, the shrinkage rate of the inner bag 4 may be greater than the shrinkage rate of the outer shell 3 during the cooling process after biaxial stretch blow molding.

[0126] In such cases, the inner bag 4 does not shrink uniformly, but rather selectively shrinks in areas of the inner bag 4 where the adhesion to the outer shell 3 is relatively weak. As a result, wrinkles may form in the inner bag 4, resulting in an unsightly appearance.

[0127] To solve these problems, in this embodiment, the inner preform 14 is configured such that the outer surface of the region including the thin-walled portion has either an uneven shape or a lubricant. In either case, the adhesion force between the inner bag 4 and the outer shell 3 is reduced, so that the inner bag 4 shrinks uniformly and the occurrence of wrinkles is suppressed.

[0128] Methods for forming the uneven shape include forming the uneven shape by post-processing of the inner preform 14, transferring the uneven shape formed on the shaping surface of the split mold for forming the inner preform 14 to the inner preform 14, and forming the uneven shape by mixing particles into the resin constituting the inner preform 14 and reflecting the shape of the particles on the surface of the inner preform 14.

[0129] Methods for forming an uneven surface by post-processing include rubbing the surface of the inner preform 14 with sandpaper or sandblasting the inner preform 14. Methods for forming an uneven surface on the shaped surface include rubbing the shaped surface with sandpaper or sandblasting the shaped surface. The particles to be mixed into the resin include inorganic particles (e.g., synthetic silicates such as talc or synthetic zeolites). The particle size is, for example, 1 to 50 μm, and the particle ratio is, for example, 0.5 to 10 mass%, with 1 to 5 mass% being preferred. This method is preferred because when an uneven surface is formed by post-processing, the adhesion between the inner bag 4 and the outer shell 3 decreases significantly.

[0130] Any lubricant with a release effect can be used. The lubricant may be applied to the outer surface of the inner preform 14, or it may be mixed into the resin constituting the inner preform 14 so that it is present on the outer surface of the inner preform 14 by bleed-out.

[0131] The uneven surface is preferably random in shape. Furthermore, the uneven surface is preferably arithmetic mean roughness Ra of 1 to 200 μm. In this case, the adhesion force between the inner bag 4 and the outer shell 3 can be reduced particularly effectively. Specifically, Ra is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, and 200 μm, and may be within the range of any two of the values ​​exemplified here. The arithmetic mean roughness Ra can be measured in accordance with JIS B 0601:2013.

[0132] Other embodiments will be described below. The contents described in the first embodiment are also applicable to the following embodiments, insofar as they do not contradict the spirit of the first embodiment.

[0133] 2. Second Embodiment In the first embodiment, a protruding seal portion 42 that is not bent is formed by direct blow molding, and the protruding seal portion 42 is bent by post-processing to form a bent structure. On the other hand, in this embodiment, as shown in Figure 25, the bent structure is formed in the protruding seal portion 42 when the inner preform 14 is direct blow molded. Even with this configuration, the stretching of the seal portion 43 during biaxial stretch blow molding can be suppressed by the same action as in the first embodiment. According to this embodiment, the effort required for post-processing can be reduced.

[0134] 3. Third Embodiment In this embodiment, the stretch-suppressing structure is formed by remelting the protruding seal portion 42 after direct blow molding of the inner preform 14, thereby reducing its surface area. Remelting causes the protruding seal portion 42 to become solid and increase its rigidity, thus functioning as a stretch-suppressing structure.

[0135] Preferably, the aspect ratio defined by [height of protruding seal portion 42 / thickness of protruding seal portion 42] is 3 or more before remelting, and the aspect ratio is reduced by remelting. In other words, in direct blow molding, as shown in Figures 26A to 26C, the protruding seal portion 42 is formed as a thin film, and the thin film protruding seal portion 42 is remelted into a block. By forming the protruding seal portion 42 as a thin film, the non-barrier region 44 where the gas barrier layer 14j is not provided is narrowed, and the protruding seal portion 42 becomes easier to remelt.

[0136] The wall thickness of the protruding seal portion 42 is, for example, 0.1 to 0.5 mm, preferably 0.1 to 0.3 mm, specifically, for example, 0.1, 0.2, 0.3, 0.4, 0.5 mm, and may be within the range of any two of the values ​​exemplified here. The height of the protruding seal portion 42 is, for example, 1.0 to 4.0 mm, preferably 1.0 to 3.0 mm, specifically, for example, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 mm, and may be within the range of any two of the values ​​exemplified here. The aspect ratio before remelting and the [aspect ratio before remelting - aspect ratio after remelting] values ​​are, for example, between 3 and 20, specifically, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20, and may also be within the range of any two of the values ​​exemplified here.

[0137] Preferably, the main body portion 14q is provided with a groove 14r along the protruding seal portion 42. In this case, the molten resin generated by remelting can be contained within the groove 14r.

[0138] 4. Fourth Embodiment In this embodiment, as shown in Figure 27, a bent structure is formed by bending the protruding seal portion 42 in a post-processing step, similar to the first embodiment. Except for the absence of the groove 14r, this embodiment functions as an elongation suppression structure through the same action as the first embodiment.

[0139] 5. Fifth Embodiment In this embodiment, as shown in Figure 28, a bent structure is formed by bending the protruding seal portion 42 by post-processing, similar to the first embodiment. This embodiment functions as a stretch-suppressing structure through the same action as the first embodiment.

[0140] 6. Sixth Embodiment As shown in Figure 29, this embodiment is similar to the first embodiment except that the mouth portion 14a of the inner preform 14 is longer than that of the first embodiment, and the shape of the protruding seal portion 42 is that of the second embodiment. By preparing an outer preform 13 and a mouth portion mounting member 8 having dimensions that fit the inner preform 14 of this embodiment, the double-walled container 1 can be manufactured in the same way as in the first embodiment. In this embodiment, the protruding seal portion 42 may be the same as that of the first or third to fifth embodiments.

[0141] 7. Seventh Embodiment This embodiment is the same as the first embodiment, except that, as shown in Figure 30, the cam mechanism 31 is composed of a cam projection 14s provided on the inner preform 14 and a cam rail 13e provided on the outer preform 13, and the inner bag 4 moves in a direction that allows it to detach from the container body 2 when rotated in the reverse screw loosening direction, an engaging projection 13f is provided on the outer preform 13, and the shape of the protruding seal portion 42 is that of the second embodiment.

[0142] A double-walled container 1 can be manufactured in the same manner as in the first embodiment using a mouth mounting member 8 that fits the inner preform 14 and outer preform 13 of this embodiment. The mouth mounting member 8 may be configured to firmly engage with the engaging projection 13f in the circumferential direction, making it impossible to rotate relative to the outer shell 3, or it may be configured to engage with the engaging projection 13f in the circumferential direction to the extent that it becomes rotatable when the inner plug rotation torque T2 described in the first embodiment is applied. In the former case, a separation band that engages with the engaging projection 13f is provided on the mouth mounting member 8, and the mouth mounting member 8 can be removed by separating the separation band. In the latter case, the mouth mounting member 8 can be removed by applying a torque of the inner plug rotation torque T2 or greater to the mouth mounting member 8 without performing an operation such as separating the separation band.

[0143] In this embodiment, the protruding seal portion 42 may be configured as that of the first or third to fifth embodiments. [Examples]

[0144] The following describes various test examples related to the above embodiment.

[0145] 1. Test Example 1 (Demonstration of the effect of the stretch-inhibiting structure) Sample 1 In Sample 1, as shown in Figure 31, an outer preform 13, as shown in Figure 31, was placed over an inner preform 14 having a protruding seal portion 42 without a stretch-suppressing structure to form a preform 15. The preform 15 was heated to 110°C (temperature at the center of the preform 15 in the height direction) and biaxially stretched blow-molded to produce a container body 2 (capacity 200 mL) with the shape shown in Figure 2 (however, the mouth portion 5 has the shape shown in Figure 31).

[0146] The inner preform 14 was manufactured by direct blow molding. The layer structure of the inner preform 14 was, from the inside out, inner layer [polypropylene / adhesive resin] / gas barrier layer [EVOH] / outer layer [adhesive resin / polypropylene / polypropylene containing 5% by mass of talc]. The thickness of each layer was measured at four points in the circumferential direction (two points in the direction of the parting line and two points perpendicular to the parting line) at the center of the height direction of the inner preform 14, and the average thickness was obtained by averaging the measured values. The thickness ratio was obtained by dividing the thickness of each layer by the total thickness of the inner preform 14. The obtained results are shown in Table 1.

[0147] [Table 1]

[0148] The outer preform 13 was manufactured by injection molding PET (type: titanium catalyst grade, manufactured by Teijin Corporation) at 300°C to form the outer preform shape, and then rapidly cooling it to 20°C. Rapid cooling converted the molten PET into an amorphous state. The outer preform 13 had an average wall thickness of 750 μm at the center in the height direction.

[0149] The inner bag 4 of the container body 2, obtained by biaxial stretch blow molding, has a height of 120 mm. The wall thickness of each layer of the inner bag 4 was measured at eight measurement points at a height of 60 mm from the bottom surface, and the average wall thickness was obtained by averaging the measured values. The wall thickness ratio was obtained by dividing the wall thickness of each layer by the total wall thickness of the inner bag 4. The obtained results are shown in Table 2. [Table 2]

[0150] When the inner bag 4 was pulled out from the container body 2 and the condition of the protruding seal portion 42 was checked, it was found that tears had occurred in the outer layer and the gas barrier layer, exposing the inner layer.

[0151] Sample 2 In Sample 2, a protruding seal portion 42 with the structure shown in Figure 28 was formed by direct blow molding, and then the protruding seal portion 42 was bent to create a stretch-suppressing structure. In other respects, the container body 2 was manufactured in the same manner as in Sample 1.

[0152] Similar to Sample 1, when the condition of the protruding seal portion 42 was checked, no cracks were found in the outer layer or the gas barrier layer.

[0153] 2. Test Example 2 (Demonstration of the effect of providing an uneven surface on the outer surface of the inner preform 14) Sample 3 In Sample 3, the container body 2 was manufactured in the same manner as in Sample 1, except that the inner preform 14 was made of a single layer of polypropylene. The body of the inner bag 4 had a height of 120 mm, and the wall thickness of the inner bag 4 was measured at eight measurement points at height positions in 10 mm increments. The average wall thickness of the joints was the average of the measurements taken at the center of the four joints 2b, the average wall thickness of the corners was the average of the measurements taken at the center of the four corners 2a, and the average wall thickness was the average of the measurements taken at the eight measurement points. The results obtained are shown in Table 3.

[0154] [Table 3]

[0155] Upon examining the exterior of container body 2 after it had cooled, numerous vertical lines were found to have formed.

[0156] Sample 4 In Sample 4, the inner preform 14 was manufactured by direct blow molding, and then the outer surface of the inner preform 14 was rubbed with #320 sandpaper to create an uneven surface. The container body 2 was manufactured in the same manner as in Sample 3. When the appearance of the container body 2 was checked after it had cooled, the inner bag 4 had shrunk uniformly and no vertical lines had formed.

[0157] Sample 5 In Sample 4, the inner preform 14 was manufactured by direct blow molding using a segmented mold with an uneven surface created by sandblasting. The container body 2 was manufactured in the same manner as in Sample 3. Upon inspection of the container body 2 after cooling, slight vertical lines were found, but these were far less pronounced than in Sample 3.

[0158] Sample 6 In Sample 6, the container body 2 was manufactured in the same manner as in Sample 3, except that 3% by mass of talc, a synthetic silicate, was added as inorganic particles to polypropylene. When the appearance of the container body 2 was examined after cooling, no vertical lines were found.

[0159] Sample 7 In Sample 7, the container body 2 was manufactured in the same manner as in Sample 3, except that 3% by mass of synthetic zeolite was added as inorganic particles to polypropylene. When the appearance of the container body 2 was examined after cooling, no vertical lines were found.

[0160] 3. Test Example 3 (Demonstration of the effect of reducing the final residue amount by squeezing out the inner bag 4) Tests No. 1 to 10 were conducted under the conditions shown in Table 4.

[0161] • Test No. 1 In Test No. 1, container body 2 was manufactured under the same conditions as Sample 3, and the contents with the viscosity shown in Table 4 were filled into container body 2 in the filling amounts shown in the same table. Then, cap 8a shown in Figure 1 was attached to the mouth 5 of container body 2.

[0162] Next, the overcap 27 was removed, and the container body 2 was tilted to dispense the contents until no more came out, and the remaining amount was measured (amount remaining after tilting). Then, the inner stopper 26 was rotated to pull the inner bag 4 out of the container body 2, and the contents were further dispensed by squeezing the inner bag 4 (amount remaining after squeezing).

[0163] • Exam No. 2 Test No. 2 was conducted in the same manner as Test No. 1, except that the inner preform 14 was formed by injection molding of PET.

[0164] • Exams No. 3-4 and 7-10 Tests No. 3-4 and 7-10 were conducted using the same method as tests No. 1-2.

[0165] • Exam No. 5-6 In tests No. 5 and 6, after pouring, the contents were dispensed until no more came out by lightly tapping the bottom 7 of the container body 2, and the remaining amount was measured (residual amount after tapping). Other aspects of the test were carried out in the same manner as in tests No. 1 and 2. [Table 4]

[0166] In all of the tests from No. 1 to 10, the final residue amount could be reduced by squeezing out the inner bag 4. A comparison between No. 1 and No. 2 showed that test No. 1, in which inner bag 4 is made of highly flexible PP, resulted in less residue after squeezing. Furthermore, while the residue amount after pouring increased significantly with increasing viscosity, the residue amount after squeezing did not increase as much as the residue amount after pouring, even with increasing viscosity. [Explanation of Symbols]

[0167] 1:Double container 2: Container body 2a: Corner 2b:Connection part 2c: Bent shape 3: Outer shell 3a: Open end 3L: Cam Rail 3m: Engaging recess 3n: Engagement protrusion 4: Inner bag 4c:Protrusion 4c1:Protruding tube 4c2: Engagement convex part 4c3: Tapered surface 4c4: Contact flange 4c5: Annular protrusion 4c6: Bottom surface 4c7 :Bottom surface 4c8: Tapered surface 4d: Inner bag body 4e: outer layer 4e1: Outermost layer 4e2: Adhesive layer 4g: Cam protrusion 4h: Engagement protrusion 4i :Inner layer 4i1: Innermost layer 4i2: Reproduction layer 4i3: Adhesive layer 4j: Gas barrier layer 4k: Expanded diameter structure 4l: Open end 4m: Engagement part 4q: Main body 5: Mouth 5b: Flange 5c: Open end 6: Torso 6b:Shoulder 6c: Torso body 7: Bottom 7a: recess 8: Mouthpiece mounting member 8a: Cap 13: External preform 13a: Mouth 13b: Torso 13c: Bottom 13d: Annular protrusion 13e: Cam rail 13f: Engagement convex part 14: Internal preform 14a: Mouth 14b: Torso 14c: Bottom 14d:Protrusion 14e :Outer layer 14i :Inner layer 14j: Gas barrier layer 14L: Expanded diameter structure 14m: Engagement part 14n: Contact flange 14o: Open end 14p: Bali 14q: Main body 14r: Groove 14s: Cam protrusion 15: Preform 15a: Mouth 15b: Torso 15c: bottom 26: Inner stopper 27: Overcap 27a: Outer cylinder 27b: Intermediate cylinder 27c: Inner cylinder 27d: Tabletop 27e: Knurling 27f: Female thread section 28: Main body 28a: Outer cylinder 28b: Inner cylinder 28c: Annular protrusion 28d: Engagement convex part 28e: Top plate 28f:Discharge tube 28g: Mounting tube 28h: Male screw part 28i: Knurled 30:Connection part 31: Cam mechanism 32: Opening part 32a: Engagement tube 33: Shrink film 33a: Easy cutting line 33b: Easy cutting line 33c: Upper part 33d: lower part 34: Cylindrical parison 35: Split mold 35a: Pinch-off section 36: Split mold 36a: Pinch-off section 38: Molded body 39: Bali 40: Fukuro 41: Annular recess 41a: Annular protrusion 42: Protruding seal portion 42a: Root part 42b:Outer part 42b1: Thick wall part 42b2: Thin-walled section 43: Seal part 43a: Sealing surface 44: Non-barrier areas

Claims

1. A method for dispensing the contents from a double container, The double-walled container comprises a container body and a cap fitted to the mouth of the container body. The container body comprises an inner bag and an outer shell positioned to cover the inner bag. The contents are contained within the inner bag. The cap is engaged with the inner bag, It includes a drawing process and a discharge process, In the extraction process, with a portion of the contents remaining inside the inner bag and the cap engaged with the inner bag, the inner bag is pulled out from the container body. In the aforementioned dispensing step, after withdrawing from the container body, the contents remaining in the inner bag are dispensed. The inner bag comprises an annular projection that engages with the cap in the axial direction and an engaging projection that engages with the cap in the circumferential direction. The method wherein the lower surface of the engaging projection is flush with the lower surface of the annular projection, or is located closer to the opening end of the inner bag than the lower surface of the annular projection.

2. The method according to claim 1, A method wherein the bottom of the container body is provided with a recess having a flattened cross-section.

3. A method according to claim 1 or claim 2, The method wherein the inner bag includes a thin-walled portion having a wall thickness of 100 μm or less.

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