Double container

Abstract

To provide a double container that is reducible in force required to draw an inner bag out.SOLUTION: There is provided a double container having a container body, which comprises an inner bag and an outer shell arranged covering the inner bag. The inner bag is configured to be drawn out of the container body, the outer shell comprises a flange part, and the container body comprises a mouth part, a trunk part, and a bottom part. The mouth part comprises an upper mouth part and a lower mouth part, the upper mouth part is a portion between an opening end of the container body and an undersurface of the flange part, and the lower mouth part is a portion between the upper mouth part and the trunk part. The container body begins to increase in outer diameter at the root of the lower mouth part below the undersurface of the flange part, the bottom part closes a lower end of the trunk part, and the outer shell comprises an inner tapered part so configured that the outer shell decreases in inner diameter toward the root at least in part at the lower opening part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a double container. [Background technology]

[0002] Patent document 1 discloses a double container that is configured so that the inner bag can be rotated relative to the outer shell by rotating a mouth attachment member that is circumferentially engaged with the inner bag relative to the outer shell, thereby twisting the inner bag to reduce its diameter, and then the mouth attachment member can be pulled to pull the inner bag out of the container body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-018821 Summary of the Invention [Problem to be solved by the invention]

[0004] If a large force is required to pull the inner bag out of the container body, it will be difficult to separate the inner bag from the container body, so it is desirable that the force required for this pulling out be small.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a double-layered container that can reduce the force required to pull out the inner bag. [Means for solving the problem]

[0006] According to the present invention, the following inventions are provided. [1] A double-walled container comprising a container body, the container body comprising an inner bag and an outer shell arranged to cover the inner bag, the inner bag being configured to be removable from the container body, the outer shell comprising a flange, the container body comprising a mouth, a body, and a bottom, the mouth comprising an upper mouth and a lower mouth, the upper mouth being the portion between the open end of the container body and the underside of the flange, the lower mouth being the portion between the upper mouth and the body, the portion below the underside of the flange where the outer diameter of the container body begins to expand being the base of the lower mouth, the bottom being the portion that closes the lower end of the body, and the outer shell comprising an inner tapered portion configured in at least a part of the lower mouth so that the inner diameter of the outer shell narrows towards the base. [2] A double container according to [1], wherein the outer shell has an outer tapered portion in at least a portion of the lower opening, configured so that the outer diameter of the outer shell narrows toward the base. [3] A double-walled container according to [2], wherein, when the lengths of the lower opening and the outer tapered portion in the axial direction of the mouth of the container body are L and Lo, respectively, Lo / L is 0.50 to 1.0. [4] A double container according to any one of [1] to [3], wherein when the lengths of the lower opening and the inner tapered portion in the axial direction of the mouth of the container body are L and Li, respectively, Li / L is 0.50 to 1.0. [5] A double-walled container according to any one of [1] to [4], wherein when the lengths of the lower opening and the opening in the axial direction of the opening of the container body are L and La, respectively, L / La is 0.25 or more. [6] A preform for use in biaxially stretched blow molding, the preform being constructed by placing an outer preform over an inner preform, the outer preform having a flange portion, and the outer preform having an inner tapered portion at an adjacent portion adjacent to the bottom surface of the outer preform on the bottom side of the flange portion, the inner diameter of the outer preform narrowing toward the bottom of the outer preform. [7] The preform according to [6], wherein the outer preform has an outer tapered portion at the adjacent portion, configured so that the outer diameter of the outer preform narrows toward the bottom of the outer preform. [8] A method for manufacturing a double container according to any one of [1] to [5], comprising a biaxial stretching molding process for biaxially stretching a preform, wherein the preform is constructed by placing an outer preform over an inner preform, the outer preform having a flange portion, and the outer preform having an inner tapered portion at an adjacent portion adjacent to the bottom surface of the outer preform, on the bottom side of the outer preform closer to the bottom surface of the flange portion, configured so that the inner diameter of the outer preform narrows toward the bottom of the outer preform. [9] The method according to [8], wherein the outer preform has an outer tapered portion at the adjacent portion, configured so that the outer diameter of the outer preform decreases toward the bottom of the outer preform.

[10] The method according to [8] or [9], wherein, when the length of the lower opening in the axial direction of the mouth of the container body is L and the length of a portion of the lower opening whose outer surface shape does not change from the shape of the preform before and after the biaxial stretch molding process is Lp, Lp / L is 0.50 to 1.00. [Effects of the Invention]

[0007] The inventors discovered that the force required to separate the inner bag increases when the thickness of the inner bag is large at the height where the undercut portion, which becomes an undercut when the inner bag is pulled out of the container body, begins. They then discovered that by providing the outer shell with an inner tapered portion configured so that the inner diameter of the outer shell narrows toward the base of the lower opening, the thickness of the undercut portion can be reduced, and therefore the force required to pull out the inner bag can be reduced, leading to the completion of the present invention. [Brief explanation of the drawings]

[0008] [Figure 1]1 is a perspective view of a double container 1 according to a first embodiment of the present invention. The dashed-dotted line in the figure indicates the boundary line where the curvature of the faces that make up the surface shape changes. The same applies to the other figures. [Figure 2] FIG. 2 is an exploded perspective view of the double container 1 of FIG. [Figure 3] 3A and 3B are a plan view and a front view, respectively, of the container body 2 in FIG. [Figure 4] Figure 4A is a longitudinal cross-sectional view of the double container 1 of Figure 1 with the overcap 42 closed. Figure 4B is an enlarged view of region B in Figure 4A. [Figure 5] FIG. 4B is an exploded view of FIG. 4A with the overcap 42 slightly open. [Figure 6] Fig. 6A is an enlarged view of region A in Fig. 5. Fig. 6B is a view corresponding to Fig. 6A in the reference example. [Figure 7] FIG. 6 is an exploded view of the container body 2 in FIG. [Figure 8] Fig. 8A is a cross-sectional view taken along line AA in Fig. 5. Fig. 8B is an enlarged view of region B in Fig. 8A. [Figure 9] 6 is a cross-sectional view taken along the line BB in FIG. 5. [Figure 10] Fig. 10A is a cross-sectional view taken along CC in Fig. 5. Fig. 10B is an enlarged view of region B in Fig. 10A. Fig. 10C is an enlarged view of region C in Fig. 10B. [Figure 11] FIG. 3 is an exploded perspective view of the container body 2 in FIG. [Figure 12] FIG. [Figure 13] FIG. 2 is a perspective view showing a state in which the inner preform 14 and the outer preform 13 are separated. [Figure 14] FIG. 1 is a perspective view of a preform 15 formed by covering an outer preform 13 on an inner preform 14. [Figure 15] FIG. 10 is a front view showing a state in which the inner preform 14 is supported by a pair of rails 45. [Figure 16] FIG. 2 is a longitudinal cross-sectional view of the preform 15. [Figure 17]1 is a cross-sectional view showing a state in which a preform 15 is attached to a blow core 21 and brought close to a heater 32. FIG. [Figure 18] 18 is a cross-sectional view showing the state after preform 15 has been transferred to molding die 23 from the state shown in FIG. 17. FIG. [Figure 19] 19 is a cross-sectional view showing the state after the bottom support mold 22 supports the bottom 15c of the preform 15 from the state of FIG. 18. FIG. [Figure 20] 20 is a cross-sectional view showing the state after the stretching rod 25 is extended and the bottom support mold 22 is retracted from the state of FIG. 19 to stretch the preform 15 in the first axis. [Figure 21] FIG. 10 is a front view of the inner bag 4 of the double container 1 of the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Each feature can be an invention independently. In the following embodiments, elements not specified in the claims are optional and can be omitted. Any number of "0"s (for example, one or two) may be added to the end of numerical values ​​disclosed in the following description. For example, one or two "0"s may be added after "1.4" to make it "1.40" or "1.400."

[0010] The embodiments shown below include at least the inventions of the following aspects: A first embodiment relates to the inventions of the first to fourth aspects, and a second embodiment relates to the inventions of the second to fourth aspects.

[0011] The invention of the first aspect is as follows: A double container comprising a container body and a mouth attachment member, The container body includes an inner bag and an outer shell disposed to cover the inner bag, The mouth attachment member is attached to a protruding portion of the inner bag that protrudes from the open end of the outer shell, The mouth portion attachment member is circumferentially engaged with the protrusion, the inner bag has a recess in a portion facing the outer shell, The recess is a double container formed by being recessed so that the inner bag protrudes inward in the recess.

[0012] The invention of the second aspect is as follows: A double container comprising a container body, The container body includes an inner bag and an outer shell disposed to cover the inner bag, The inner bag has a protrusion on its outer circumferential surface that protrudes radially outward, The outer shell has grooves, the convex ribs and the concave ribs are configured to be engageable with each other by relative rotation of the inner bag and the outer shell in one direction, and to be disengaged with each other by relative rotation of the inner bag and the outer shell in the other direction, The outer shell has an engaging protrusion on an inner circumferential surface that protrudes radially inward, the protrusion includes a first other-side abutment surface that abuts against the engaging protrusion when the protrusion is rotated relatively in the other direction, The first other-side contact surface is a double container that is an end surface located at an end in the longitudinal direction of the ridge.

[0013] The first invention of the third aspect is: A double container comprising a container body, The container body includes an inner bag and an outer shell disposed to cover the inner bag, The inner bag is configured to be removable from the container body, The outer shell includes a flange portion, The container body has a mouth, a body, and a bottom, The mouth portion includes an upper mouth portion and a lower mouth portion, the upper opening portion is a portion between the open end of the container body and the lower surface of the flange portion, the lower opening is a portion between the upper opening and the body, a portion where the outer diameter of the container body begins to increase below the lower surface of the flange portion is the base of the lower opening portion; the bottom portion is a portion that closes the lower end of the body portion, The outer shell is a double container having an inner tapered portion in at least a portion of the lower opening portion such that the inner diameter of the outer shell narrows toward the base.

[0014] The second invention of the third aspect is: A preform for use in biaxial stretch blow molding, The preform is configured by covering an outer preform with an inner preform, the outer preform has a flange portion; The outer preform is a preform having an inner tapered portion at an adjacent portion adjacent to the lower surface of the outer preform, closer to the bottom of the outer preform than the lower surface of the flange portion, and configured so that the inner diameter of the outer preform narrows toward the bottom of the outer preform.

[0015] The invention of the fourth aspect is as follows: A double container comprising a container body and a mouth attachment member, The container body includes an inner bag and an outer shell disposed to cover the inner bag, The mouth attachment member is attached to a protruding portion of the inner bag that protrudes from the open end of the outer shell, the inner bag and the outer shell are in contact with each other at a contact surface on the inner bag side and a contact surface on the outer shell side, The abutment surface on the outer shell side is inclined so as to face the inside of the outer shell, making it a double container.

[0016] 1. First embodiment The double-sided container 1 of the first embodiment of the present invention will be described using Figures 1 to 20. In the following description, terms related to directions, such as "upper" and "lower," refer to directions when the bottom 7 is in contact with the ground. In addition, in the following description, the "axial direction" refers to the direction in which the central axis C (shown in Figure 2) of the mouth 5 extends, for example, the direction in which the inner bag 4 is pulled out from the container body 2. The "circumferential direction" refers to the rotational direction around the central axis C of the mouth 5, for example, the direction in which the inner bag 4 is rotated relative to the outer shell 3 at the mouth 5. Unless otherwise specified, "clockwise" and "counterclockwise" refer to directions as viewed from the top of the double-sided container 1.

[0017] 1-1. Structure of double container 1 As shown in Fig. 1, the double container 1 of the first embodiment of the present invention comprises a container body 2 and a spout attachment member 8. Each component will be described in detail below.

[0018] <Configuration of container body 2> As shown in FIGS. 2 and 3, the container body 2 includes a mouth 5, a body 6, and a bottom 7. The mouth 5 is a tubular (preferably cylindrical) portion having an open end 5c. The open end 5c is the open end of the container body 2 and also the open end of the inner bag 4 shown in FIG. 5. The mouth 5 includes an engagement portion 4m to which a mouth attachment member 8 can be attached. The engagement portion 4m is provided on the protruding portion 4c of the inner bag 4. As shown in FIGS. 11 and 12, the mouth 5 includes an axial engagement portion 4ma that engages with the mouth attachment member 8 in the axial direction, and a circumferential engagement portion 4mb that engages with the mouth attachment member 8 in the circumferential direction. The axial engagement portion 4ma and the circumferential engagement portion 4mb are provided so as to protrude radially outward from the peripheral wall 4b1. As shown in FIG. 8, a recess 4c13 is provided on the inner peripheral surface of the axial engagement portion 4ma. It is preferable that the mouth attachment member 8 does not engage with the outer shell 3.

[0019] The body 6 is disposed adjacent to the mouth 5 on a side farther from the open end 5c than the mouth 5. The body 6 has a larger outer diameter (in this specification, "outer diameter" means the equivalent circular diameter when the cross section is not circular) than the mouth 5. The body 6 is cylindrical, and the bottom 7 is provided at the lower end of the body 6 and closes the lower end of the body 6. The body 6 has a shoulder 6b whose outer diameter increases with increasing distance from the mouth 5. The body 6 also has a body main body 6c on the bottom 7 side of the shoulder 6b. The body main body 6c has a shape in which the outer diameter is approximately constant toward the bottom 7, or a shape in which the diameter decreases toward the bottom 7, for example.

[0020] As shown in Fig. 3, the mouth 5 has an upper mouth 5a and a lower mouth 5b. The upper mouth 5a is the region between the open end 5c of the container body 2 and the lower surface 5d1 of the flange 5d. The lower mouth 5b is the region between the upper mouth 5a and the body 6. The base 5b1 of the lower mouth 5b is the region below the lower surface 5d1 of the flange 5d where the outer diameter of the container body 2 begins to expand.

[0021] The shoulder 6b has an uneven shape 6d in which recesses 6d1 and protrusions 6d2 are alternately arranged in the circumferential direction. The protrusions 6d2 extend at an inclination counterclockwise from the boundary 6e between the shoulder 6b and the body main body 6c toward the base 5b1 of the mouth 5. The extension direction of the protrusions 6d2 coincides with the direction in which the inner bag 4 is rotated when the inner bag 4 is pulled out of the container main body 2. That is, in this embodiment, as will be described later, the inner bag 4 is rotated counterclockwise when the inner bag 4 is pulled out, so the protrusions 6d2 are also provided to incline counterclockwise. Providing the uneven shape 6d on the shoulder 6b facilitates regular folding of the inner bag 4 when the inner bag 4 is rotated relative to the outer shell 3, making it easier to reduce the diameter of the inner bag 4.

[0022] The outer surface of base 5b1 preferably has a curved shape that convexly curves inward. The radius of curvature is preferably 3 mm or greater. Setting this radius of curvature to such a value prevents base 5b1 from getting caught on outer shell 3 when inner bag 4 is pulled out. The radius of curvature is, for example, 3 to 10 mm, preferably 3 to 7 mm, and specifically, for example, 3, 4, 5, 6, 7, 8, 9, or 10 mm, and may be within a range between any two of the values ​​exemplified here.

[0023] The trunk main body 6c is provided with a pair of groove-shaped ribs 6f1, 6f2. The groove-shaped ribs 6f1, 6f2 extend circumferentially and are spaced apart from each other in the direction of the central axis C. The provision of the groove-shaped ribs 6f1, 6f2 increases the rigidity of the trunk main body 6c.

[0024] As shown in Figures 4 to 8, the container body 2 includes an inner bag 4 and an outer shell 3 arranged to cover the inner bag 4. As shown in Figure 5, the inner bag 4 includes a protruding portion 4c that protrudes from the open end 3a of the outer shell 3. A mouth attachment member 8 is attached to the protruding portion 4c. The inner bag 4 has an inner bag body 4d housed within the outer shell 3, excluding the protruding portion 4c. The inner bag 4 is configured to be removable from the container body 2. In the following description, the portions of the inner bag 4 that correspond to the mouth 5, body 6, and bottom 7 of the container body 2 will be referred to as the mouth 5, body 6, and bottom 7 of the inner bag 4, respectively. The same applies to the outer shell 3.

[0025] <Details of the opening 5 of the inner bag 4> As shown in Figures 8, 11 and 12, the inner bag 4 includes a first tube 4a and a second tube 4b. The first tube 4a is disposed within the outer shell 3. The second tube 4b has a larger outer diameter than the first tube 4a and is disposed closer to the open end 5c of the inner bag 4 than the first tube 4a. The entire second tube 4b may be disposed outside the outer shell 3, or part or all of the second tube 4b may be disposed within the outer shell 3, with the remainder disposed outside the outer shell 3.

[0026] As shown in Figures 8 and 12, the second tube 4b has a peripheral wall 4b1 and a bottom wall 4b2 provided below the peripheral wall 4b1 and configured to reduce the diameter of the peripheral wall 4b1 toward the first tube 4a. The inner bag 4 is arranged so that the bottom surface 4b4 of the second tube 4b abuts against the outer shell 3. The abutment of the bottom surface 4b4 against the outer shell 3 prevents the inner bag 4 from entering the outer shell 3. The peripheral wall 4b1 preferably extends parallel to the axial direction. The bottom wall 4b2 is preferably arranged within the outer shell 3.

[0027] The angle α of the peripheral wall 4b1 relative to the bottom wall 4b2 is preferably 90 degrees or greater, and more preferably 95 degrees or greater. In this case, the bending of the inner bag 4 at the corner 4b3 between the bottom wall 4b2 and the peripheral wall 4b1 is relatively gentle, making it less likely to break when an impact is applied, thereby improving impact resistance. This angle is, for example, 90 to 135 degrees (105 degrees in this embodiment), preferably 95 to 115 degrees, and specifically, for example, 90, 95, 100, 105, 110, 115, 120, 125, 130, or 135 degrees, or may be in a range between any two of the values ​​exemplified here.

[0028] The length L1 between the underside 4b4 at the corner 4b3 and the underside 4m3 of the axial engagement portion 4ma is preferably 2 mm or more. In this case, local bending of the inner bag 4 is further suppressed. The length L1 is, for example, 2 to 10 mm, and preferably 3 to 6 mm (4.5 mm in this embodiment). Specific examples of the length L1 are 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, and 10.0 mm, and may be in a range between any two of the values ​​exemplified here. The length from the underside 4b4 of the portion of the peripheral wall 4b1 that is parallel to the axial direction is preferably within the above-mentioned range, and the portion between the underside 4b4 and the underside 4m3 is preferably parallel to the axial direction.

[0029] As shown in Figures 4, 9, and 11-12, the inner bag 4 has a recess 4h in a portion facing the outer shell 3. The recess 4h is recessed so that the inner bag 4 protrudes inward at the recess 4h. When the spout attachment member 8 is attached to the protruding portion 4c as in this embodiment, if the protruding portion 4c is not sufficiently rigid, the protruding portion 4c may be twisted by a rotational force applied to the spout attachment member 8, making it difficult to transmit the rotational force to the portion of the inner bag 4 housed within the outer shell 3, making it difficult to twist the inner bag 4. In the configuration of this embodiment, the recess 4h functions as a rib that reinforces the protruding portion 4c. This makes it easier to transmit the rotational force applied to the spout attachment member 8 to the portion of the inner bag 4 housed within the outer shell 3, making it easier to twist the inner bag 4.

[0030] Furthermore, in the double-walled container 1 of this embodiment, before attaching the mouth attachment member 8, a leak test for the inner bag 4 may be performed by sucking out the air from inside the inner bag 4 through the mouth 5 to shrink the inner bag 4. During this process, air must be introduced into the intermediate space between the inner bag 4 and the outer shell 3 to prevent the outer shell 3 from shrinking along with the inner bag 4. If the outer shell 3 does not have an air inlet hole for introducing air into the intermediate space, as in this embodiment, deformation of the mouth 5 of the inner bag 4 may form a gap between the inner bag 4 and the outer shell 3 at the mouth 5, allowing air to be introduced into the intermediate space. Such deformation of the mouth 5 of the inner bag 4 is undesirable because it can lead to defects. In this embodiment, the inner bag 4 has a recess 4h in a portion facing the outer shell 3. Air can be introduced into the intermediate space between the inner bag 4 and the outer shell 3 through the recess 4h, thereby suppressing deformation of the mouth 5 of the inner bag 4.

[0031] In this embodiment, the recess 4h is provided at the corner 4b3 between the bottom wall 4b2 and the peripheral wall 4b1. In this case, the recess 4h functions as a reinforcing rib, increasing the rigidity of the second tube 4b, making it easier to rotate the inner bag 4 relative to the outer shell 3 when pulling out the inner bag 4. The corner 4b3 is also located inside the outer shell 3. In this case, a gap is unlikely to form between the inner bag 4 and the outer shell 3, so the provision of the recess 4h to make it easier for air to be introduced into the intermediate space between the inner bag 4 and the outer shell 3 is of significant technical significance.

[0032] <Details of the mouth 5 of the outer shell 3> As shown in FIG. 4, the open end 3a of the outer shell 3 is provided with a base surface 3a1, an annular protrusion 3a2, and an inner bag support surface 3a3. The base surface 3a1 is preferably annular. The annular protrusion 3a2 is disposed inside the base surface 3a1 and protrudes axially from the base surface 3a1. As shown in FIG. 4, the base surface 3a1 faces the open end 41a1 of the outer tube 41a of the mouth-attached member 8, and the annular protrusion 3a2 protrudes toward the inside of the outer tube 41a of the mouth-attached member 8. With this configuration, even if foreign matter, such as the contents of the inner bag 4, enters the gap 44 between the base surface 3a1 and the open end 41a1, the annular protrusion 3a2 prevents the foreign matter from entering between the inner bag 4 and the outer shell 3. Furthermore, it is preferable that the apex 3a4 of the annular protrusion 3a2 be higher than the open end 41a1. In this case, the intrusion of the contents is further prevented.

[0033] As shown in FIG. 8 , the inner bag support surface 3a3 is the surface against which the lower surface 4b4 of the second tube 4b abuts. The inner bag support surface 3a3 is preferably annular. By abutting the lower surface 4b4 against the inner bag support surface 3a3, the inner bag 4 is supported by the outer shell 3, preventing the inner bag 4 from penetrating into the outer shell 3. The inner bag support surface 3a3 is disposed inside the base surface 3a1 and the annular protrusion 3a2. The inner bag support surface 3a3 is preferably located lower than the base surface 3a1. In this case, a portion of the peripheral wall 4b1 near the lower wall 4b2 is covered by the outer shell 3, which inevitably covers the lower wall 4b2 and the corners 4b3 as well. This protects the corners 4b3, which have relatively low impact resistance, with the outer shell 3, further improving the impact resistance of the inner bag 4.

[0034] As shown in Figure 7, the outer peripheral surface of the outer shell 3 is provided with an expanded diameter portion 3o and a flange portion 5d in this order from the opening end 3a of the outer shell 3. The expanded diameter portion 3o is formed by expanding the diameter of the opening end 3a. A recess 3g is preferably provided on the inner peripheral surface of the expanded diameter portion 3o. The lower surface of the recess 3g serves as the inner bag support surface 3a3.

[0035] <Tapered section details> The double-layered container 1 of this embodiment is designed to have the inner bag 4 pulled out of the container body 2. If the force required for this pulling is excessive, it becomes difficult to pull the inner bag 4 out of the container body 2. Therefore, it is desirable to reduce the force required to pull out the inner bag 4 (the force required to twist the inner bag 4 when the inner bag 4 is being twisted while being pulled out). Studies to reduce this force were conducted and found that during biaxial stretch blow molding, the thickness of the lower opening 5b of the outer shell 3 decreases toward the base 5b1, resulting in the formation of an undercut portion 4u that becomes an undercut when the inner bag is pulled out of the container body. The undercut portion 4u is located closer to the outer shell 3 than the vertical line v shown in FIGS. 6A and 6B. The greater the thickness of the inner bag 4 at height position H, which is the starting point of the undercut portion 4u, the greater the force required to pull out the inner bag 4.

[0036] In a reference example without an inner tapered portion 3p as shown in Figure 6B, height position H, where the undercut portion 4u starts, is located near the underside 5d1 of the flange 5d. At this height position, the thickness of the inner bag 4 is relatively large, so a relatively large force is required to pull out the inner bag 4. In contrast, in the present embodiment shown in Figure 6A, the outer shell 3 is provided with an inner tapered portion 3p in at least a portion of the lower opening 5b, which is configured so that the inner diameter of the outer shell 3 decreases toward the base 5b1 of the lower opening 5b. Therefore, height position H, where the undercut portion 4u starts, moves in a direction closer to the base 5b1. Because the thickness of the inner bag 4 decreases toward the base 5b1, providing the inner tapered portion 3p reduces the force required to pull out the inner bag 4.

[0037] The outer shell 3 preferably has an outer tapered portion 3q in at least a part of the lower opening 5b so that the outer diameter of the outer shell 3 decreases toward the base 5b1. In this case, the inner tapered portion 3p is more likely to be formed.

[0038] If the lengths of the lower opening 5b, the inner tapered portion 3p, and the outer tapered portion 3q in the axial direction of the mouth 5 of the container body 2 are L, Li, and Lo, respectively, then Li / L and Lo / L are preferably each 0.50 to 1.00 (in this embodiment, both are 1.00). In this case, the torque required to pull out the inner bag 4 is more effectively reduced. Li / L and Lo / L are each preferably 0.75 to 1.00, and specific examples thereof are 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, and 1.00, and may be within a range between any two of the numerical values ​​exemplified here.

[0039] The inner tapered portion 3p has an angle η1 at its maximum relative to the central axis C of, for example, 1 to 20 degrees (4 degrees in this embodiment), and preferably 1 to 10 degrees. Specific examples of this angle η1 are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 degrees, and may be in a range between any two of the values ​​exemplified here. The outer tapered portion 3q has an angle η2 at its maximum relative to the central axis C of, for example, 2 to 25 degrees (7 degrees in this embodiment), and preferably 4 to 12 degrees. Specifically, angle η2 is, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 degrees, or may be in a range between any two of the values ​​exemplified here. Angle η2 is preferably larger than angle η1, and the value of (angle η2 - angle η1) is, for example, 1 to 10 degrees, or specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 degrees, or may be in a range between any two of the values ​​exemplified here.

[0040] 3, where La is the length of the mouth 5 of the container body 2 in the axial direction of the mouth 5, it is preferable that L / La is 0.25 or more (0.36 in this embodiment). The larger the proportion of the lower opening 5b in the mouth 5, the more likely it is that the pull-out force for the inner bag 4 will increase, and therefore the greater the L / La, the more significant the technical significance of applying the present invention. L / La is, for example, 0.25 to 0.60, and specifically, for example, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, or 0.60, and may be within a range between any two of the values ​​exemplified here. L is, for example, 5 to 20 mm (9.7 mm in this embodiment), preferably 8 to 15 mm, and specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mm, or may be in a range between any two of the values ​​exemplified here. La is, for example, 15 to 50 mm (26.8 mm in this embodiment), preferably 20 to 40 mm, and specifically, for example, 15, 20, 25, 30, 35, 40, 45, or 50 mm, or may be in a range between any two of the values ​​exemplified here.

[0041] <Details of the contact structure between the inner bag 4 and the outer shell 3> 8, the inner bag 4 and the outer shell 3 abut against each other at a contact surface 4i on the inner bag 4 side and a contact surface 3i on the outer shell 3 side. In this embodiment, the lower surface 4b4 of the inner bag 4 abuts against the inner bag support surface 3a3 of the outer shell 3, so that the lower surface 4b4 is the abutment surface 4i and the inner bag support surface 3a3 is the abutment surface 3i.

[0042] The contact surface 3i (or the inner bag support surface 3a3) is preferably inclined so as to face the inside of the outer shell 3. In other words, the contact surface 3i is inclined so as to approach the open end 3a as it moves radially outward. When the spout attachment member 8 is attached to the protruding portion 4c of the inner bag 4 and not to the outer shell 3, as in this embodiment, the spout attachment member 8 is likely to rattle relative to the outer shell 3 when gripped. If the spout attachment member 8 rattles relative to the outer shell 3, the double container 1 becomes uncomfortable to use, so it is desirable to suppress rattle of the spout attachment member 8 relative to the outer shell 3. In this embodiment, the contact surface 3i on the outer shell 3 side is inclined so as to face the inside of the outer shell 3, so the protruding portion 4c of the inner bag 4 is easily positioned by the contact surface 3i on the outer shell 3 side, and rattle of the spout attachment member 8 relative to the outer shell 3 is suppressed.

[0043] The angle β of the contact surface 3i with respect to a reference plane P perpendicular to the central axis C of the mouth portion 5 is, for example, 5 to 45 degrees (15 degrees in this embodiment), preferably 10 to 30 degrees. Specifically, the angle β may be, for example, 5, 10, 15, 20, 25, 30, 35, 40, or 45 degrees, and may be within a range between any two of the values ​​exemplified here. The contact surface 4i and the contact surface 3i are preferably parallel. When the contact surface 4i and the contact surface 3i are inclined with respect to the reference plane P and parallel to each other, the contact area tends to be larger than when the contact surface 4i and the contact surface 3i are parallel to the reference plane P, making it less likely that a gap will form between the inner bag 4 and the outer shell 3. This highlights the technical significance of providing a recess 4h in the inner bag 4 to ensure an air flow path.

[0044] <Details of cam mechanism 31> 10 to 12, a ridge 4g that protrudes radially outward is provided on the outer peripheral surface 4j of the inner bag 4 (more specifically, the inner bag main body 4d). As shown in Fig. 12, the lower surface of the ridge 4g is inclined so as to approach the open end 5c in the counterclockwise direction.

[0045] As shown in Fig. 10, multiple ridges 4g are provided on the outer peripheral surface 4j of the inner bag 4, and the multiple ridges 4g are arranged circumferentially offset from each other. In this embodiment, two ridges 4g are arranged circumferentially offset by 180 degrees. The angle at which each ridge 4g extends is preferably 180 degrees or less, and more preferably 90 degrees or less. This angle is, for example, 15 to 180 degrees, and preferably 30 to 90 degrees (approximately 45 degrees in this embodiment). Specific examples of this angle include 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, and 180 degrees, and may be in a range between any two of the values ​​exemplified here.

[0046] As shown in Fig. 12, the ridges 4g are arranged adjacent to the recesses 4h and closer to the bottom than the recesses 4h (i.e., below the recesses 4h). As shown in Figs. 3 and 5, the ridges 4g are arranged at the mouth 5 (preferably the upper mouth 5a). As will be described later, the inner bag 4 is formed by biaxially stretching blow molding the inner preform 14. In biaxially stretching blow molding, the area above the lower surface 5d1 of the flange 5d is hardly deformed, so as shown in Fig. 15, the inner preform 14 is provided with recesses 14h and ridges 14g corresponding to the recesses 4h and ridges 4g. During mass production, for example, the inner preforms 14 are transported in an aligned state by being supported by each of a pair of rails 45 of the part feeder at the portion 14b2 corresponding to the bottom wall 4b2, but the portion of the portion 14b2 that is circumferentially aligned with the recesses 14h or the ridges 14g is difficult to support with the rails 45. Therefore, if the recesses 14h and the ridges 14g are misaligned in the circumferential direction, the portion of the portion 14b2 that is easily supported by the rails 45 becomes narrower, making it difficult to transport the inner preforms 14 stably with the part feeder. On the other hand, in this embodiment, the ridges 4g are positioned adjacent to the recesses 4h, so the circumferential positions of the recesses 14h and the ridges 14g are aligned, making it easy to transport the inner preforms 14 stably with the part feeder.

[0047] As shown in FIG. 11, the inner peripheral surface of the outer shell 3 is provided with a recess 3m that can engage with the protrusion 4g. The recess 3m is preferably provided at the end of the cam rail 3l. The upper surface of the cam rail 3l is inclined so as to approach the opening end 3a as it progresses counterclockwise. The protrusion 4g and the recess 3m are configured to be engageable by relative rotation of the inner bag 4 and the outer shell 3 in one direction, and to be disengageable by relative rotation of the inner bag 4 and the outer shell 3 in the other direction. With the protrusion 4g and the recess 3m engaged, it is preferable that the contact surface 4i of the inner bag 4 be pressed against the contact surface 3i of the outer shell 3, as shown in FIG. 8. In this case, rattle of the mouth attachment member 8 relative to the outer shell 3 is further suppressed.

[0048] A plurality of cam rails 3l are provided on the inner peripheral surface of the outer shell 3, and the plurality of cam rails 3l are offset from one another in the circumferential direction. In this embodiment, two cam rails 3l are arranged offset by 180 degrees in the circumferential direction. The angle at which each cam rail 3l extends is preferably 360 degrees or less, and more preferably 270 degrees or less. This angle is, for example, 90 to 360 degrees, and preferably 120 to 240 degrees (180 degrees in this embodiment). Specific examples of this angle include 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, and 360 degrees, and may be in a range between any two of the values ​​exemplified here.

[0049] The recessed strips 3m are preferably provided on each cam rail 3l. The angle at which the recessed strips 3m extend is the same as the angle at which the protruding strips 4g extend.

[0050] Before the inner bag 4 is pulled out of the container body 2, the lower surface of the ridge 4g abuts against the upper surface of the cam rail 3l within the groove 3m. The ridge 4g and the cam rail 3l form a cam mechanism 31. When the inner bag 4 is rotated counterclockwise relative to the outer shell 3, the cam mechanism 31 causes the inner bag 4 to displace in a direction that pulls it out of the container body 2. At this time, the inner bag 4 is twisted and its diameter is reduced. The cam mechanism 31 has an inclined structure that is inclined in the same direction as a right-handed screw.

[0051] <Details of rotation restriction structure> The container body 2 is preferably provided with a rotation restriction structure that restricts relative rotation between the inner bag 4 and the outer shell 3. Examples of this rotation restriction structure include a structure that increases the frictional force between the inner bag 4 and the outer shell 3, and a structure that engages the inner bag 4 and the outer shell 3 in a concave-convex manner in the circumferential direction. In this embodiment, as shown in Figures 10 and 11, the outer shell 3 has an engaging protrusion 3j on its inner circumferential surface 3n that protrudes radially inward. The engaging protrusion 3j is preferably arranged along the cam rail 3l, and more preferably arranged within or adjacent to the recessed groove 3m.

[0052] As shown in FIG. 10, the ridge 4g includes a first contact surface 4g1 that contacts the engaging protrusion 3j when the ridge 4g is rotated relative to the engaging protrusion 3j in one direction (i.e., the engaging direction), a second contact surface 4g2 that contacts the engaging protrusion 3j when the ridge 4g is rotated relative to the engaging protrusion 3j in the other direction (i.e., the disengaging direction), and a central surface 4g3 between the first contact surface 4g1 and the second contact surface 4g2. The first contact surface 4g1 and the second contact surface 4g2 are end surfaces located at the longitudinal ends of the ridge 4g. The central surface 4g3 has a shape similar to that of the portion 3r of the outer shell 3 that the central surface 4g3 faces. No protrusion is provided on the central surface 4g3. At the central surface 4g3, the ridge 4g has a constant protruding height from the outer peripheral surface 4j. The height of the ridge 4g decreases monotonically from the center in the longitudinal direction of the ridge 4g toward the bases 4g4, 4g5 at both ends in the longitudinal direction of the ridge 4g.

[0053] In a configuration in which a separate protrusion is provided on the central surface 4g3 of the rib 4g and this protrusion abuts against the engaging protrusion 3j, the protrusion is likely to become thin during molding, resulting in breakage and leakage of the contents. In contrast, in this embodiment, instead of providing a separate protrusion on the central surface 4g3, the end faces of the rib 4g at its longitudinal ends abut against the engaging protrusion 3j of the outer shell, thereby preventing the inner bag 4 from unexpectedly rotating relative to the outer shell 3. Since the end faces of the rib 4g are less likely to become thin than when a separate protrusion is provided on the central surface 4g3, this embodiment prevents breakage of the inner bag 4. The rib 4g may be hollow or solid. However, when the rib 4g is hollow, the technical significance of abutting the end faces of the rib 4g at its longitudinal ends against the engaging protrusion 3j of the outer shell is significant. When the inner bag 4 is formed using an inner preform 14 formed by direct blow molding, the rib 4g is typically hollow.

[0054] The other-side contact surface 4g2 has a second-side inclination angle θ2, which is the inclination angle of the base 4g4 of the other-side contact surface 4g2 with respect to the tangent 4j2 of the outer peripheral surface 4j, of 5 to 45 degrees (19 degrees in this embodiment), preferably 10 to 40 degrees. The outer peripheral surface 4j is preferably circular in cross section, and the portion protruding from the circular outer peripheral surface 4j is preferably the ridge 4g. The other-side inclination angle θ2 is preferably 10 to 30 degrees, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, or 45 degrees, and may be in a range between any two of the values ​​exemplified here. The smaller the other-side inclination angle θ2, the less likely the ridge 4g is to be thinned. Furthermore, if the other-side inclination angle θ2 is greater than 45 degrees, the ridge 4g is too thinned, which may easily deform when the other-side contact surface 4g2 is pressed against the engaging protrusion 3j, resulting in insufficient regulation of relative rotation.

[0055] The one-side inclination angle θ1, which is the inclination angle of the one-side contact surface 4g1 at the base 4g5 with respect to the tangent 4j1 of the outer peripheral surface 4j, is larger than the other-side inclination angle θ2. In this case, the thickness of the one-side contact surface 4g1 tends to be relatively thin, and the torque required for engagement between the rib projection 4g and the rib recess 3m can be reduced. The one-side inclination angle θ1 is, for example, 50 to 80 degrees (64 degrees in this embodiment), and preferably 55 to 75 degrees. Specifically, the one-side inclination angle θ1 may be, for example, 50, 55, 60, 65, 70, 75, or 80 degrees, and may be in a range between any two of the values ​​exemplified here. The difference between the one-side inclination angle θ1 and the other-side inclination angle θ2 is, for example, 30 to 60 degrees (44 degrees in this embodiment), and preferably 35 to 55 degrees. This difference may be, for example, 30, 35, 40, 45, 50, 55, or 60 degrees, or may be in a range between any two of the values ​​exemplified here.

[0056] The engaging protrusion 3j has a one-side contact surface 3j1 that contacts the protrusion 4g when the engaging protrusion 3j is rotated relative to the rib 4g in one direction (i.e., the engaging direction), and a other-side contact surface 3j2 that contacts the protrusion 4g when the engaging protrusion 3j is rotated relative to the rib 4g in the other direction (i.e., the disengaging direction). The one-side contact surface 3j1 contacts the one-side contact surface 4g1, and the other-side contact surface 3j2 contacts the other-side contact surface 4g2.

[0057] The one-side inclination angle δ1, which is the inclination angle of the one-side contact surface 3j1 with respect to the connecting line 3j6 connecting the base 3j5 of the one-side contact surface 3j1 and the base 3j4 of the other-side contact surface 3j2, is, for example, 20 to 50 degrees (31 degrees in this embodiment), and preferably 25 to 45 degrees. Specifically, the one-side inclination angle δ1 is, for example, 20, 25, 30, 35, 40, 45, or 50 degrees, and may be in a range between any two of the values ​​exemplified here. The other-side inclination angle δ2, which is the inclination angle of the other-side contact surface 3j2 with respect to the connecting line 3j6, is 50 to 80 degrees (60 degrees in this embodiment), and preferably 55 to 75 degrees. Specifically, the other-side inclination angle δ2 is, for example, 50, 55, 60, 65, 70, 75, or 80 degrees, and may be in a range between any two of the values ​​exemplified here. The engaging protrusions 3j are preferably solid bodies, and in this case, the greater the inclination angle, the greater the torque required for engagement or disengagement. In this embodiment, the one-side inclination angle δ1 is smaller than the other-side inclination angle δ2, so a configuration is realized in which the torque required for engagement between the ribs 4g and the recesses 3m is relatively low, and the torque required for disengagement between the ribs 4g and the recesses 3m is relatively high. The difference between the one-side inclination angle δ1 and the other-side inclination angle δ2 is, for example, 15 to 50 degrees (29 degrees in this embodiment), and preferably 20 to 40 degrees. Specific examples of this difference include 20, 25, 30, 35, 40, 45, and 50 degrees, and may be within a range between any two of the values ​​exemplified here.

[0058] <Detailed configuration of mouth attachment member 8> 4 and 5, the mouth-mounted member 8 preferably has a discharge port 8d for discharging the contents in the inner bag 4. The mouth-mounted member 8 also preferably includes a nozzle 8c.

[0059] The cap 8a preferably includes a cap body 41 and an overcap 42. The cap body 41 is configured to be able to engage with the protrusion 4c and includes a discharge port 8d. The overcap 42 is configured to be able to open and close the discharge port 8d. FIG. 4 shows a closed state in which the discharge port 8d is closed, and FIG. 5 shows an open state in which the discharge port 8d is open. In this embodiment, the cap body 41 and the overcap 42 are connected by a hinge 43, but they do not have to be connected. The overcap 42 is preferably able to engage with the cap body 41 by a screw or a snap fit.

[0060] The cap body 41 includes an outer tube 41a, an inner tube 41b, a nozzle 8c, and an upper wall 41d. The inner tube 41b is disposed inside the outer tube 41a. The outer tube 41a and inner tube 41b are connected via the upper wall 41d. The nozzle 8c is disposed above the upper wall 41d. A flow hole 41i is provided in the upper wall 41d, and the flow passages of the inner tube 41b and the nozzle 8c are connected through the flow hole 41i. The tip of the nozzle 8c forms the discharge port 8d. The inner tube 41b is inserted into the protruding portion 4c and is in close contact with the inner surface 4f1 of the cylindrical seal portion 4f. As a result, the inner tube 41b and the cylindrical seal portion 4f are frictionally engaged in the circumferential direction. An engagement portion 8b is provided on the inner peripheral surface of the outer tube 41a.

[0061] The overcap 42 comprises an outer tube 42a, an inner tube 42b, and an upper wall 42d. The inner tube 42b is disposed inside the outer tube 42a. The outer tube 42a and the inner tube 42b are connected via the upper wall 42d. The upper wall 42d does not have a discharge port for discharging the contents of the inner bag 4.

[0062] When the discharge port 8d is closed by the overcap 42, the inner tube 42b is inserted into the nozzle 8c of the cap body 41 and is in close contact with the inner surface of the nozzle 8c. The bottom surface of the outer tube 42a abuts against the upper wall 41d of the cap body 41. In this state, by gripping the outer tube 42a and applying an upward force to the overcap 42, the overcap 42 can be separated from the cap body 41 to open the discharge port 8d.

[0063] <Attachment of mouth attachment member 8> As shown in FIG. 5, the neck mounting member 8 can be attached to the neck 5 with the enlarged diameter portion 3o or the flange portion 5d supported. The neck mounting member 8 is preferably a plug-type member. With the enlarged diameter portion 3o or the flange portion 5d supported, the neck mounting member 8 is placed over the protruding portion 4c. When a downward force is applied to the neck mounting member 8 in this state, the engaging portion 8b overcomes the axial engaging portion 4ma and engages with the axial engaging portion 4ma and the circumferential engaging portion 4mb, thereby attaching the neck mounting member 8 to the neck 5. The engaging portion 8b engages with the axial engaging portion 4ma in the axial direction and with the circumferential engaging portion 4mb in the circumferential direction. The circumferential engagement between the circumferential engaging portion 4mb and the engaging portion 8b may be a concave-convex engagement or a frictional engagement.

[0064] <Pull out inner bag 4> The mouth attachment member 8 is engaged with the protruding portion 4c of the inner bag 4 in the circumferential and axial directions, and is configured to rotate relative to the outer shell 3 so that the inner bag 4 twists as the mouth attachment member 8 rotates. The action of a cam mechanism 31 provided between the inner bag 4 and the outer shell 3 causes the inner bag 4 to move in a direction that allows it to come out of the container body 2 as the inner bag 4 rotates.

[0065] With this configuration, by rotating the mouth attachment member 8, the inner bag 4 can be twisted and moved in a direction that allows it to come out of the container body 2, and then by pulling the mouth attachment member 8, the inner bag 4 can be pulled out of the container body 2.

[0066] 1-2. Manufacturing method of double container 1 The container body 2 can be manufactured by biaxially stretching blow molding a preform 15 shown in Fig. 14. In addition, the double container 1 can be manufactured by attaching a mouth attachment member 8 to the container body 2.

[0067] <Configuration of inner preform 14, outer preform 13, and preform 15> The preform 15 includes an inner preform 14 that will become the inner bag 4 and an outer preform 13 that will become the outer shell 3.

[0068] As shown in Fig. 13, the inner preform 14 is cylindrical with a bottom, and includes a mouth portion 14a, a body portion 14b, and a bottom portion 14c. A protrusion 14d is provided on the mouth portion 14a. As shown in Figs. 13 and 14, the protrusion 14d is a portion of the preform 15 that protrudes from the open end 13f of the outer preform 13. The protrusion 14d does not deform during molding, and becomes the protrusion 4c in its original shape. The protrusion 14d is provided with an engagement portion 14m that becomes the engagement portion 4m. The bottom portion 14c is provided to close the lower end of the body portion 14b.

[0069] The inner preform 14 also has a recess 14h at a location facing the outer preform 13. The recess 14h is preferably recessed so that the inner preform 14 protrudes inward at the recess 14h. The inner preform 14 has a ridge 14g on its outer circumferential surface 14j that protrudes radially outward. The ridge 14g is positioned adjacent to the recess 14h, closer to the bottom 14c than the recess 14h. With this configuration, as shown in FIG. 15, the inner preform 14 can be supported by a pair of rails 45 of the parts feeder and easily transported stably.

[0070] 13, the outer preform 13 is cylindrical with a bottom, and includes a mouth portion 13a, a body portion 13b, and a bottom portion 13c. The bottom portion 13c is provided so as to close the lower end of the body portion 13b.

[0071] 16, the outer preform 13 has a flange portion 15e. The outer preform 13 has an inner tapered portion 13p in an adjacent region 13g adjacent to the bottom 13c of the outer preform 13 on the side closer to the bottom 13c of the outer preform 13 than the lower surface 15e1 of the flange portion 15e, configured so that the inner diameter of the outer preform 13 decreases toward the bottom 13c of the outer preform 13. The outer preform 13 also has an outer tapered portion 13q in the adjacent region 13g, configured so that the outer diameter of the outer preform 13 decreases toward the bottom 13c of the outer preform 13. In this case, the inner tapered portion 3p is formed in the outer shell 3, and the force required to pull out the inner bag 4 is likely to be reduced.

[0072] If the length of the adjacent portion 13g in the direction in which the central axis C1 of the mouth portion 13a of the outer preform 13 extends (hereinafter referred to as the "outer preform axial direction") is pL, then pL is preferably the same as the length L of the lower mouth portion 5b. pL is the length in the outer preform axial direction, for example, 5 to 20 mm (9.7 mm in this embodiment), preferably 8 to 15 mm, and specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mm, and may be in a range between any two of the numerical values ​​exemplified here.

[0073] If the lengths of the inner tapered portion 13p and the outer tapered portion 13q in the axial direction of the outer preform are pLi and pLo, respectively, then pLi / pL and pLo / pL are preferably each 0.50 to 1.00. In this case, the torque required to pull out the inner bag 4 is more effectively reduced. pLi / pL and pLo / pL are each preferably 0.75 to 1.00, and specific examples thereof are 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, and 1.00, and may be within a range between any two of the values ​​exemplified here.

[0074] The angle ε1 of the inner tapered portion 13p at the portion where the angle with respect to the central axis C1 is greatest in the adjacent portion 13g is, for example, 2 to 30 degrees (13 degrees in this embodiment), and preferably 5 to 20 degrees. Specifically, the angle ε1 may be, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 degrees, or may be in a range between any two of the numerical values ​​exemplified here.

[0075] The outer tapered portion 13q has an angle ε2 at the portion of the adjacent portion 13g where the angle with respect to the central axis C1 is maximum, which is, for example, 2 to 25 degrees (7 degrees in this embodiment), and preferably 4 to 12 degrees. Specifically, the angle ε2 may be, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 degrees, or may be in a range between any two of the values ​​exemplified here.

[0076] It is preferable that angle ε1 is larger than angle ε2, and the value of (angle ε1 - angle ε2) is, for example, 1 to 25 degrees, specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 degrees, or may be in a range between any two of the values ​​exemplified here.

[0077] 14, a preform 15 can be formed by covering an inner preform 14 with an outer preform 13. In the preform 15, the mouth portion 14a faces the mouth portion 13a, and the body portion 14b faces the body portion 13b.

[0078] The mouth portions 13a and 14a become the mouth portion 15a of the preform 15, the body portions 13b and 14b become the body portion 15b of the preform 15, and the bottom portions 13c and 14c become the bottom portion 15c of the preform 15. In this embodiment, the portion of the flange portion 15e closer to the bottom portion 15c than the lower surface 15e1 is mainly stretched during biaxial stretch blow molding. The portion of the flange portion 15e closer to the opening end 15f than the lower surface 15e1 is hardly deformed during molding, and the outer surface shape of the adjacent portion 13g is also hardly deformed during biaxial stretch molding. With regard to the portion that is hardly deformed during biaxial stretch molding, the contents described in relation to the container body 2 can also be applied to the preform 15, as long as they are not contrary to the spirit thereof.

[0079] <Materials and manufacturing methods for inner preform 14, outer preform 13, and preform 15> The inner preform 14 and the outer preform 13 can be formed from a thermoplastic resin such as polyester (e.g., PET) or polyolefin (e.g., polypropylene, polyethylene). The outer preform 13 can be formed by direct blow molding or injection molding. The inner preform 14 is preferably formed by direct blow molding using a molten cylindrical parison. Direct blow molding has the advantage of easily achieving thinner walls and multi-layered structures compared to injection molding. A seal portion is formed on the bottom 14c of the inner preform 14 formed by direct blow molding, by welding the inner surfaces of the parison together. This seal portion has relatively low strength and is prone to tearing during biaxial stretch blow molding. Therefore, in order to increase the strength of the seal portion, it is preferable that the seal portion be a protruding seal portion 14t that protrudes from the bottom 14c of the inner preform 14.

[0080] <Biaxial stretch blow molding process> The biaxial stretch blow molding process will be described with reference to Figures 17 to 20. In the biaxial stretch blow molding process, the preform 15 is attached to the blow core 21 so that the insertion portion 21b of the blow core 21 is positioned within the preform 15, and the preform 15 is then biaxially stretch blow molded into the shape of the container body 2.

[0081] In one example, the biaxial stretch blow molding process includes a mounting step, a heating step, and a stretching step. Each step will be described below.

[0082] <Installation process> In the mounting step, as shown in FIG. 17 , the preform 15 is mounted to the blow core 21 so that the insertion portion 21b of the blow core 21 is positioned within the preform 15. The blow core 21 includes a base portion 21a, an insertion portion 21b, and a through-hole 21c. The insertion portion 21b is provided so as to protrude from the base portion 21a. The insertion portion 21b is inserted into the preform 15.

[0083] <Heating process> The heating process can be performed using a heating device 35 shown in FIG. 17. In the heating process, the preform 15 is heated and softened to a softened state. In one example, the heating process can be performed by placing the preform 15 in close proximity to a heater 32 while the preform 15 is attached to a blow core 21, as shown in FIG. 17. The heating process is performed by covering the flange portion 15e of the preform 15 with a heat shield 33 and heating the portion of the flange portion 15e closer to the bottom 15c than the lower surface 15e1. This softens the heated portion. On the other hand, the portion of the flange portion 15e closer to the open end 15f than the lower surface 15e1 receives little or no heat from the heater 32 and is not softened. In one example, the preform 15 can be heated while being rotated. In one example, the heater 32 is composed of multiple rod-shaped heaters arranged along the side of the preform 15, but other configurations are also possible.

[0084] <Stretching process> The stretching step can be performed using a blow molding device 36 shown in Figures 18 to 20. In the stretching step, the softened preform 15 is stretched to form the shape of the container body 2. In one example, the stretching step includes a first stretching step and a second stretching step.

[0085] <First stretching process> In the first stretching step, the preform 15 is stretched along a first axial direction (i.e., the vertical direction). The first axis is, for example, a direction parallel to the central axis C of the mouth portion 5, which is the up-and-down direction in FIG. 18. In one example, this step can be performed by setting the heated preform 15 in a molding die 23 as shown in FIGS. 18 and 19, and then, with the bottom 15c of the preform 15 supported by a bottom support die 22 as shown in FIGS. 19 and 20, pressing a stretch rod 25 inserted through a through hole 21c provided in the blow core 21 against the inner bottom surface of the inner preform 14 to stretch it. At this time, it is preferable to retract the bottom support die 22 in synchronization with the stretching of the stretch rod 25. This allows the preform 15 to be stably stretched.

[0086] The preform 15 can be transferred from the heating device 35 to the blow molding device 36 while supported by the blow core 21. The molding die 23 is composed of a split mold that can be opened and closed, and has a cavity surface 23a that corresponds to the outer surface shape of the container body 2, and a flange abutment surface 23d against which the lower surface 15e1 of the flange portion 15e abuts. The first stretching step can be performed with the lower surface 15e1 of the flange portion 15e abutting against the flange abutment surface 23d.

[0087] <Second stretching process> In the second stretching step, air is blown into the inner preform 14 from the state shown in Fig. 20 to stretch (i.e., expand) the preform 15 in the second axial direction (i.e., the lateral direction) and shape it into the shape of the cavity surface 23a, thereby obtaining the container body 2 shown in Fig. 2. Air can be blown in through the through holes 21c provided in the blow core 21.

[0088] If Lp is the length of a portion of the lower opening 5b of the container body 2 whose outer surface shape remains unchanged from the shape of the preform 15 before and after the biaxial stretch molding step, then Lp / L is preferably 0.50 to 1.00. Providing the inner tapered portion 13p and / or the outer tapered portion 13q in the outer preform 13 facilitates the formation of the inner tapered portion 13p and / or the outer tapered portion 13q in the lower opening 5b of the container body 2. Lp / L is preferably 0.75 to 1.00, and specific examples of Lp / L are 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, and 1.00, and may be within a range between any two of the numerical values ​​exemplified here.

[0089] In one example, by matching the shape of the portion 23e of the cavity surface 23a that faces the adjacent portion 13g to the shape of the adjacent portion 13g, the shape of the adjacent portion 13g can be made to match the shape of the lower opening portion 5b of the container body 2.

[0090] 2. Second embodiment As shown in Figure 21, the second embodiment is the same as the first embodiment except that it does not have a recess 4h. This embodiment is suitable for use when it is necessary to form a seal structure between the inner bag 4 and the outer shell 3 at the opening 5. In this embodiment, it is preferable to adopt a configuration in which the abutment surfaces 4i and 3i are inclined and parallel to the reference plane P and abut against each other. In this case, the abutment area tends to be larger than when the abutment surfaces 4i and 3i are parallel to the reference plane P, making it less likely that a gap will form between the inner bag 4 and the outer shell 3. This makes it possible to prevent air leakage through the gap between the inner bag 4 and the outer shell 3.

[0091] This embodiment is suitable for use when the double container 1 is a so-called peelable container in which the inner bag 4 contracts as the contents are discharged. In this case, the opening attachment member 8 is preferably provided with a discharge valve that prevents outside air from entering the inner bag 4 while allowing the contents to be discharged from the inner bag 4. It is also preferable to provide an outside air inlet hole for introducing outside air into the intermediate space between the inner bag 4 and the outer shell 3, and to provide an outside air inlet valve in this outside air inlet hole that allows outside air to be introduced into the intermediate space while preventing outside air from being discharged from the intermediate space. This configuration makes it possible to realize a squeeze-type peelable container.

[0092] 3. Third embodiment The direction of relative rotation of each component may be reversed from that of the above embodiment. In other words, while the above embodiment is configured such that the inner bag 4 is displaced in the direction of coming out of the container body 2 by rotating the clockwise screw in the loosening direction, the inner bag 4 may also be displaced in the direction of coming out of the container body 2 by rotating the counterclockwise screw in the loosening direction. In this case, the lower surface of the ridge 4g and the upper surface of the cam rail 3l are inclined so as to approach the opening end 5c as they move clockwise when viewed from the opening end side of the container body 2. Furthermore, it is preferable that the ridge 6d2 be shaped to extend at an angle clockwise from the boundary 6e toward the base 5b1 of the mouth 5. [Explanation of symbols]

[0093] 1:Double container 2: Container body 3: Outer shell 3a: Open end 3a1: Base surface 3a2: Annular convex part 3a3: inner bag support surface 3a4: Vertex 3g: recess 3i: Contact surface 3j: Engagement convex part 3j1: One side contact surface 3j2: Other side contact surface 3j4 : Root 3j5 : Root 3j6: Connecting line 3l: Cam rail 3m: Concave strip 3n: Inner peripheral surface 3o: Diameter-expanded part 3p: Inner tapered part 3q: Outer tapered part 3r: Part 4: Inner bag 4a: First cylinder 4b: Second cylinder 4b1: Peripheral wall 4b2: Bottom wall 4b3: Corner part 4b4: Bottom surface 4c: Protrusion 4c13: Recess 4d: Inner bag body 4f: Seal cylinder part 4f1: Inner surface<00​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​6f1: Grooved rib 6f2: Grooved rib 7: Bottom 8: Mouth attachment member 8a: Cap 8b: Engagement part 8c: Nozzle 8d:Discharge port 13: Outer preform 13a: Mouth 13b: Torso 13c: Bottom 13f: Open end 13g: Adjacent area 13p: Inner tapered section 13q: Outer tapered section 14: Inner preform 14a: Mouth 14b: Torso 14b2 : Part 14c: Bottom 14d:Protrusion 14g: Convex strip 14h: recess 14j: Outer surface 14m: Engagement part 14t: Protruding seal part 15: Preform 15a: Mouth 15b: Body 15c: bottom 15e: Flange part 15e1: Bottom surface 15f: Open end 21: Blow Core 21a: base 21b: Insertion part 21c: Through hole 22: Bottom support type 23: Molding mold 23a: Cavity surface 23d: Flange contact surface 23e : Part 25: Stretching rod 31: Cam mechanism 32: Heater 33: Heat shielding section 35: Heating device 36: Blow molding equipment 41: Cap body 41a: Outer cylinder 41a1: Open end 41b: Inner cylinder 41d: Upper wall 41i :Flow hole 42: Overcap 42a: Outer cylinder 42b: Inner cylinder 42d: Upper wall 43: Hinge 44: Gap 45: Rail C: Central axis C1: Central axis H: Height position P: Reference plane v: vertical line

Claims

1. A double container comprising a container body, The container body includes an inner bag and an outer shell disposed to cover the inner bag, The inner bag is configured to be removable from the container body, The outer shell includes a flange portion, The container body has a mouth, a body, and a bottom, The mouth portion includes an upper mouth portion and a lower mouth portion, the upper opening portion is a portion between the open end of the container body and the lower surface of the flange portion, the lower opening is a portion between the upper opening and the body, a portion where the outer diameter of the container body begins to increase below the lower surface of the flange portion is the base of the lower opening portion; the bottom portion is a portion that closes the lower end of the body portion, The outer shell has an inner tapered portion configured such that the inner diameter of the outer shell narrows toward the base at at least a portion of the lower opening.

2. The double container according to claim 1, The outer shell has an outer tapered portion configured so that the outer diameter of the outer shell narrows toward the base at at least a portion of the lower opening.

3. The double container according to claim 2, A double container, wherein, when the lengths of the lower opening and the outer tapered portion in the axial direction of the mouth of the container body are L and Lo, respectively, Lo / L is 0.50 to 1.

0.

4. The double container according to claim 1, A double container, wherein, when the lengths of the lower opening and the inner tapered portion in the axial direction of the mouth of the container body are L and Li, respectively, Li / L is 0.50 to 1.

0.

5. The double container according to claim 1, A double container, wherein L / La is 0.25 or more, where L and La are the lengths of the lower opening and the opening in the axial direction of the opening of the container body.

6. A preform for use in biaxial stretch blow molding, The preform is configured by covering an outer preform with an inner preform, the outer preform has a flange portion; The outer preform has an inner tapered portion at an adjacent portion adjacent to the lower surface of the outer preform, closer to the bottom of the outer preform than the lower surface of the flange portion, and configured so that the inner diameter of the outer preform narrows toward the bottom of the outer preform.

7. 7. The preform according to claim 6, The outer preform has an outer tapered portion at the adjacent portion, the outer preform being configured such that the outer diameter of the outer preform decreases toward the bottom of the outer preform.

8. A method for manufacturing a double container according to any one of claims 1 to 5, A biaxial stretching molding step is provided for biaxially stretching the preform, The preform is configured by covering an outer preform with an inner preform, the outer preform has a flange portion; The method includes the step of forming an inner tapered portion at a location adjacent to the lower surface of the flange portion on the bottom side of the outer preform and adjacent to the lower surface, the inner diameter of the outer preform narrowing toward the bottom of the outer preform.

9. 9. The method of claim 8, The method wherein the outer preform comprises an outer tapered portion at the adjacent portion configured such that an outer diameter of the outer preform decreases toward a bottom of the outer preform.

10. 9. The method of claim 8, The length of the lower opening in the axial direction of the opening of the container body is L, When the length of a portion of the lower opening portion, the outer surface shape of which does not change from the shape of the preform before and after the biaxial stretch molding step, is Lp, Lp / L is 0.50 to 1.00.

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