Double container

Abstract

To provide a double container which inhibits twisting of an inner bag when a mouth part attachment member having an inner ring is attached.SOLUTION: According to the invention, a double container comprises a container body and a mouth part attachment member. The container body includes a mouth part, a body part, and a bottom part. The mouth part is a tubular portion having an open end. The body part is arranged adjacent to the mouth part on a side farther from the open end than the mouth part and has a larger outer diameter than the mouth part. The bottom part is configured to close a lower end of the body part. The container body includes an inner bag and an outer shell arranged so as to cover the inner bag. The mouth part attachment member includes a female screw part which may threadedly engage with a male screw part of the mouth part of the outer shell. The double container is configured to inhibit the inner bag from being twisted in conjunction with rotation in one direction of the mouth part attachment member. The one direction is a tightening direction of the mouth part attachment member. The double container of the invention is excellent in recyclability and thus can be preferably used for manufacturing of a recycled material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention discloses a dual container. [Background technology]

[0002] Conventionally, double containers having a container body with an outer shell and an inner bag have been known. For example, Patent Document 1 discloses that an outer shell preform and an inner bag preform are stacked together and biaxially stretched blow molded to form a double container (so-called delaminating container) configured so that the inner bag shrinks as the contents decrease. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-10741 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the outer shell and inner bag of such a double container are made of different materials, or when contents remain inside the inner bag after use, it is desirable to separate the outer shell and inner bag when recycling the double container.

[0005] To facilitate separation of the inner bag from the outer shell, it is preferable to fit the inner bag and outer shell loosely at the mouth of the container body so that the inner bag is not clamped to the outer shell. However, this makes it easier for the inner bag to rotate relative to the outer shell at the mouth of the container body. After filling such a container body with contents, if a mouth-attaching component (such as a cap or pump) having an inner ring is screwed onto the mouth of the container body, friction between the inner ring and the inner surface of the mouth may cause the mouth of the inner bag and the cap to rotate together, resulting in twisting of the inner bag. If the inner bag twists, the contents inside the inner bag may overflow.

[0006] The present invention has been made in consideration of these circumstances, and provides a double container in which twisting of the inner bag is suppressed when a mouth attachment member having an inner ring is attached. [Means for solving the problem]

[0007] According to the present invention, the following inventions are provided. [1] A double container comprising a container body and a mouth attachment member, wherein the container body comprises a mouth, a body, and a bottom, the mouth being a tubular portion having an open end, the body being positioned adjacent to the mouth on a side farther from the open end than the mouth and having a larger outer diameter than the mouth, the bottom being configured to close the lower end of the body, the container body comprising an inner bag and an outer shell arranged to cover the inner bag, the mouth attachment member having a female thread portion that can be threaded into the male thread portion of the mouth of the outer shell, the double container being configured to be able to prevent the inner bag from twisting as the mouth attachment member is rotated in one direction, the one direction being the tightening direction of the mouth attachment member. [2] A double-walled container as described in [1], wherein the container body is a biaxially stretched blow-molded body, the body portion has a shoulder portion whose outer diameter increases as it moves away from the mouth portion, and the inner bag and the outer shell abut at any of the shoulder portion, the body portion, and the bottom portion. [3] The double container according to [2], wherein the outer surface of the inner bag and the inner surface of the outer shell have the same inclination angle at the shoulder portion. [4] A double container as described in any one of [1] to [3], wherein the inner bag has a plurality of engaging protrusions spaced apart in the circumferential direction, and the mouth attachment member has a plurality of claw portions spaced apart in the circumferential direction, and the inner bag and the mouth attachment member engage in the circumferential direction by engaging the engaging protrusions of the inner bag with the claw portions of the mouth attachment member in the circumferential direction. [5] The double container according to any one of [1] to [4], wherein the inner bag is configured to rotate in accordance with the rotation of the opening attachment member. [6] The double container according to any one of [1] to [5], wherein the inner bag has a cylindrical shape in the entire portion facing the mouth of the outer shell. [7] A double container according to any one of [1] to [6], wherein the bottoms of the inner bag and the outer shell are each provided with a bottom recessed area and a peripheral area surrounding the bottom recessed area. [8] A double container according to [7], wherein the thickness of each of the inner bag and the outer shell gradually decreases around the periphery of the bottom recessed region as it approaches the peripheral region. [9] The double container according to [8], wherein the peripheral surface is an inclined surface that slopes away from the center of the bottom portion toward the peripheral region.

[10] A double-walled container according to any one of [7] to [9], wherein the bottom of the inner bag has an alternating thickness shape in which thin-walled sections and thick-walled sections that are thicker than the thin-walled sections alternate in the circumferential direction, and the alternating thickness shape is provided on at least one of the peripheral surface of the bottom recessed region and the peripheral region.

[11] A double-walled container according to

[10] , wherein the thin-walled portion is formed by providing grooves on one or both of the inner and outer surfaces of the inner bag.

[12] The double container according to any one of [1] to

[11] , wherein the inner bag is configured not to shrink when the contents of the inner bag are discharged. [Effects of the Invention]

[0008] The double container of the present invention is configured to be able to prevent the inner bag from twisting when the spout attachment member is rotated in one direction. Therefore, by setting the spout attachment member to be tightened in one direction, twisting of the inner bag when the spout attachment member is attached is prevented. [Brief explanation of the drawings]

[0009] [Figure 1]This is a front view of the double container 1 of the first embodiment of the present invention, showing the state in which the spout attachment member 8 is separated from the container body 2. The dashed dotted line in the figure indicates the boundary where the curvature of the faces that make up the surface shape changes. The same applies to the other figures. [Figure 2] 2A is a cross-sectional view taken along line AA in FIG. 1, FIG. 2B is an end view of cross-section BB in FIG. 2A, FIG. 2C is an enlarged view of region C in FIG. 2B, and FIG. 2D is an end view of cross-section DD in FIG. 2A. [Figure 3] 3A is an enlarged perspective view of the vicinity of the mouth portion 5 in FIG. 1, and FIG. 3B is an enlarged view of region B in FIG. 3A. [Figure 4] FIG. 4A is a perspective view of the mouth-mounted member 8 with a part cut away, and FIG. 4B is a perspective view of the mouth-mounted member 8 as seen obliquely from below. [Figure 5] 5A is a front view of the spout-mounted member 8 mounted on the container body 2, and FIG. 5B is a cross-sectional view taken along line BB in FIG. 5A. [Figure 6] 6A is a cross-sectional view taken along line BB in FIG. 1, FIG. 6B is a front view of the inner bag 4 near the bottom of the container body 2, and FIG. 6C is a cross-sectional view taken along line CC in FIG. 6B. [Figure 7] 7A is a perspective view of the vicinity of the bottom of the container body 2 as seen obliquely from below, and FIG. 7B is a perspective view of the inner bag 4 with the outer shell 3 removed from FIG. 7A. [Figure 8] 8A is a perspective view of the vicinity of the bottom of the container body 2 as seen obliquely from above, and FIG. 8B is a perspective view of the inner bag 4 with the outer shell 3 removed from FIG. 8A. [Figure 9] FIG. 2 is a perspective view showing a state in which the inner preform 14 and the outer preform 13 are separated. [Figure 10] Figure 10A is a front view of the inner preform 14, Figures 10B to 10C are cross-sectional views taken along lines BB and CC in Figure 10A, respectively, Figure 10D is an enlarged view of cross-section DD in Figure 10A, and Figure 10E is a perspective view of the inner preform 14 seen obliquely from above. [Figure 11]Figure 11A is an oblique view showing the state in which the outer preform 13 is being placed on the inner preform 14, Figure 11B is an enlarged view of region B in Figure 11A, Figure 11C is an end view of a cross section passing through the center of the protrusion 14f and the center of the inner preform 14 in Figure 11A, and Figure 11D is an enlarged view of region D in Figure 11C. [Figure 12] FIG. 1 is a perspective view of a preform 15 formed by covering an outer preform 13 on an inner preform 14. [Figure 13] 3B is a perspective view corresponding to FIG. 3A, in which only the outer shell 3 is taken out from the container body 2 in the second embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently.

[0011] 1. First embodiment 1-1. Structure of double container 1 As shown in FIG. 1, a double container 1 according to one embodiment of the present invention comprises a container body 2 and a spout attachment member 8. The double container 1 has a container body 2 and a spout attachment member 8. The spout attachment member 8 is made of a polypropylene resin.

[0012] As shown in FIG. 1, the container body 2 has a mouth 5, a body 6, and a bottom 7. The mouth 5 is a tubular (preferably cylindrical) portion with an open end 5c. The mouth 5 has an engagement portion 5a to which a mouth attachment member 8, such as a cap or a pump, can be attached. The engagement portion 5a is a male thread portion 5a1 if the mouth attachment member 8 is a screw-type, or a ring-shaped protrusion protruding in the circumferential direction if the mouth attachment member 8 is a stopper-type. The mouth attachment member 8 may have a check valve (not shown). In this case, the contents can be discharged through the mouth attachment member 8, but outside air is prevented from entering the container body 2. The mouth 5 has a flange 5b. The flange 5b can be used to support the mouth 5 when the mouth attachment member 8 is attached to the mouth 5.

[0013] The body 6 is disposed adjacent to the mouth 5 on the 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 circumscribed circle diameter if 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, and a body main body 6c which is provided on the bottom 7 side of the shoulder 6b and has a substantially constant outer diameter.

[0014] The diameter of the mouth portion 5 excluding the engaging portion 5a is, for example, 20 to 40 mm, preferably 25 to 35 mm, and specifically, for example, 20, 25, 30, 35, or 40 mm, and may be within a range between any two of the numerical values ​​exemplified here. The length of the mouth portion 5 is, for example, 15 to 35 mm, and specifically, for example, 15, 20, 25, 30, or 35 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0015] As shown in Fig. 2, the container body 2 includes an inner bag 4 and an outer shell 3 arranged to cover the inner bag 4. The inner bag 4 is housed within the outer shell 3 except for a protruding portion 4c, which will be described later. 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.

[0016] If the mouth attachment member 8 is provided with a check valve, the inner bag 4 contracts as the contents of the inner bag 4 are discharged. If the mouth attachment member 8 is not provided with a check valve, the inner bag 4 does not contract even after the contents of the inner bag 4 are discharged, making it difficult to pull out the inner bag 4 through the mouth 5 of the outer shell 3. The present invention facilitates pulling out the inner bag 4 through the mouth 5 of the outer shell by twisting the inner bag 4 to reduce its diameter, so the significance of applying the present invention is particularly evident when the mouth attachment member 8 is not provided with a check valve. However, even if the mouth attachment member 8 is provided with a check valve, the diameter of the inner bag 4 may not appropriately reduce when it contracts, so the significance of applying the present invention is also evident when the mouth attachment member 8 is provided with a check valve.

[0017] An outside air inlet hole 16 is provided in the body 6 or the bottom 7. The outside air inlet hole 16 is a through-hole that penetrates the outer shell 3, and outside air can be introduced into the intermediate space between the outer shell 3 and the inner bag 4 through the outside air inlet hole 16. When the double container 1 is a so-called squeeze-type container that ejects the contents by compressing the outer shell 3, it is preferable to provide a check valve that controls the flow of air in and out through the outside air inlet hole 16. The check valve is preferably configured to close the outside air inlet hole 16 when the outer shell 3 is compressed and to open the outside air inlet hole 16 when the compressive force is released. In this case, when a compressive force is applied to the outer shell 3, the compressive force is more easily applied to the inner bag 4, and after the contents are ejected, outside air is quickly introduced into the intermediate space, allowing the outer shell 3 to quickly restore its shape.

[0018] When a check valve is provided in the outside air introduction hole 16, it is preferable that the outside air introduction hole 16 be disposed in a recess 6d provided in the body 6. In this case, it is possible to prevent the check valve from interfering with the shrink film when the body 6 is covered with the shrink film. It is also preferable to provide a groove 6e extending from the recess 6d toward the mouth 5. The groove 6e extends to a position that is not covered with the shrink film. This prevents the recess 6d from being sealed with the shrink film.

[0019] As shown in FIG. 2, the inner surface of at least one of the mouth 5 and a position of the body 6 adjacent to the mouth 5 is preferably provided with an uneven pattern 9 in which grooves 9a and protrusions 9b alternate in the circumferential direction of the mouth 5. The uneven pattern 9 is provided on the inner surface of the inner bag 4. The number of grooves 9a is, for example, 4 to 30, and preferably 10 to 20. The grooves 9a and protrusions 9b preferably extend non-parallel to the circumferential direction of the mouth 5. The extending direction of the grooves 9a and protrusions 9b is preferably 0 to 60 degrees, and preferably 0 to 30 degrees, relative to the axial direction of the mouth 5. Specific examples of this angle are 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 degrees, and may be within a range between any two of the values ​​exemplified here. The uneven shape 9 may be provided only in the mouth 5 or may be provided in a position on the body 6 adjacent to the mouth 5, but is preferably provided across the mouth 5 and body 6. The uneven shape 9 may be formed by reducing the thickness of the recesses 9a or by increasing the thickness of the protrusions 9b compared to other parts of the mouth 5 of the inner bag 4, or by reducing the thickness of the recesses 9a and increasing the thickness of the protrusions 9b.

[0020] Because the thickness of the ridges 9b is greater than the thickness of the recesses 9a, when the twist applied by the mouth 5 is transmitted to the body 6, the force is transmitted more easily to the ridges 9b than to the recesses 9a, and the ridges 9b rotate faster than the recesses 9a, resulting in the formation of creases in the inner bag 4 along the recesses 9a and their extensions, making it easier for the inner bag 4 to fold into pleats. For this reason, providing the uneven surface 9 causes the body 6 to fold into pleats, thereby quickly reducing the diameter of the body 6. It is preferable not to provide an uneven surface on the outer surface of the inner bag 4. This is because if an uneven surface is provided on the outer surface of the inner bag 4, the inner bag 4 and the outer shell 3 will engage with each other in the rotational direction of the inner bag 4, making it more difficult for the inner bag 4 to rotate relative to the outer shell 3.

[0021] If the thickness of the inner bag 4 at the ridges 9b of the mouth 5 (the radius of the circumscribing circle of the inner bag 4 minus the radius of the inscribed circle passing through the apexes of the ridges 9b) is T and the depth of the recesses 9a (the radius of the inscribed circle passing through the bottoms of the recesses 9a minus the radius of the inscribed circle passing through the apexes of the ridges 9b) is D, the maximum value of D / T is, for example, 0.2 to 0.8, and preferably 0.3 to 0.5. Specific examples of this value are 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8, and may be within a range between any two of the values ​​exemplified here. The thickness of the inner bag 4 at the mouth 5 other than the concave-convex shape 9 is, for example, 1 to 2 mm, specifically, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 mm, or may be within a range between any two of the numerical values ​​exemplified here. The depth of the concave streaks 9a at the portion where the depth is greatest is, for example, 0.3 to 1.0 mm, specifically, for example, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 mm, or may be within a range between any two of the numerical values ​​exemplified here.

[0022] The distance from the opening edge 5c of the mouth portion 5 to the upper end of the uneven shape 9 is, for example, 0 to 30 mm, specifically, for example, 0, 5, 10, 15, 20, 25, or 30 mm, and may be within a range between any two of the numerical values ​​exemplified here. The distance from the upper end to the lower end of the uneven shape 9 is, for example, 10 to 40 mm, specifically, for example, 10, 15, 20, 25, 30, 35, or 40 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0023] As shown in Figures 6 to 8, a protrusion 4e is provided on the bottom 7 of the inner bag 4. An annular protrusion 3b is provided on the bottom 7 of the outer shell 3, and a through-hole 3c is provided in the area inside the annular protrusion 3b. The protrusion 4e is inserted into the through-hole 3c, thereby positioning the inner bag 4 with respect to the outer shell 3. The annular protrusion 3b and its area inside it are hardly stretched during biaxial stretch blow molding, so both the outer shell 3 and the inner bag 4 have a large wall thickness.

[0024] If the outer diameter of the annular protrusion 3b is D1 and the inner diameter of the mouth portion 5 of the outer shell 3 is D2, then D1 / D2 is preferably 0.9 or less. Since the thickness of the inner bag 4 is greater at the annular protrusion 3b and the region inside it, the smaller D1 / D2 is, the more easily the diameter of the bottom portion 7 of the inner bag 4 is reduced. D1 / D2 is, for example, 0.1 to 0.9, and specifically, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9, and may be within a range between any two of the numerical values ​​exemplified here.

[0025] The bottom 7 of the container body 2 (i.e., the bottoms 7 of the inner bag 4 and the outer shell 3) is provided with a bottom recessed region 7a and a peripheral region 7b surrounding the bottom recessed region 7a. The bottom recessed region 7a is a region of the bottom 7 recessed toward the inside of the container body 2. The peripheral region 7b serves as the contact surface of the container body 2. As shown in FIG. 6A, the thickness of the inner bag 4 and the outer shell 3 gradually decreases along the peripheral surface 7a1 of the bottom recessed region 7a as it approaches the peripheral region 7b. The peripheral surface 7a1 is an inclined surface that slopes away from the center of the bottom 7 toward the peripheral region 7b. In other words, the peripheral surface 7a1 forms part of a cone that tapers toward the bottom surface 7a2 of the bottom recessed region 7a. The bottom surface 7a2 of the bottom recessed region 7a is generally flat. Therefore, the bottom recessed region 7a has a generally truncated cone shape.

[0026] The bottom surface 7a2 of the bottom recessed region 7a is difficult to stretch during biaxial stretch blow molding and is therefore likely to have a large wall thickness. Therefore, the smaller the diameter D3 of the bottom surface 7a2 (in other words, the diameter of the region surrounded by the boundary between the bottom surface 7a2 and the peripheral surface 7a1), the easier it is for the bottom 7 of the inner bag 4 to be reduced in diameter. D3 / D2 is preferably 0.9 or less. D3 / D2 is, for example, 0.1 to 0.9, specifically, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9, and may be within a range between any two of the values ​​exemplified here.

[0027] 6 to 8, the bottom 7 of the inner bag 4 is provided with an alternating thickness shape 10 in which thin sections 10a and thick sections 10b that are thicker than the thin sections 10a appear alternately in the circumferential direction of the inner bag 4. By providing the bottom 7 with the alternating thickness shape 10, when the inner bag 4 is twisted, the thin sections 10a are bent, causing the bottom 7 to deform like an accordion, making it easier for the diameter of the bottom 7 to be reduced.

[0028] As shown in FIG. 6C , the peripheral surface 7a1 is thicker than the side surface 4d of the inner bag 4 near the bottom 7. Therefore, providing the alternating thickness shape 10 on the peripheral surface 7a1 is particularly important for facilitating the diameter contraction of the bottom 7. Furthermore, the peripheral region 7b is less likely to deform than the side surface 4d of the inner bag 4 near the bottom 7. Therefore, providing the alternating thickness shape 10 on the peripheral region 7b is particularly important. Therefore, it is preferable to provide the alternating thickness shape 10 on at least one of the peripheral surface 7a1 and the peripheral region 7b of the bottom recessed region 7a, and it is even more preferable to provide the alternating thickness shape 10 so that it straddles the peripheral surface 7a1 and the peripheral region 7b. It is also preferable to provide the alternating thickness shape 10 so that it straddles the peripheral region 7b and the side surface 4d of the inner bag 4. Providing the alternating thickness shape 10 in this manner makes the bottom 7 even easier to contract.

[0029] 7B, the thin portions 10a and the thick portions 10b are preferably provided so as to extend radially from the center of the bottom portion 7. The number of thin portions 10a is, for example, 4 to 30, and preferably 10 to 20.

[0030] The thin-walled portion 10a can be formed by providing grooves 11 on one or both of the inner and outer surfaces of the inner bag 4. The grooves 11 on the inner surface of the inner bag 4 and the grooves 11 on the outer surface face each other. The area between two adjacent grooves 11 becomes the thick-walled portion 10b.

[0031] In a cross section perpendicular to the height direction of the inner bag 4 (such as the cross section in FIG. 6C ), if the thickness of the inner bag 4 at the thin-walled portion 10a is T1 and the thickness of the inner bag 4 at the thick-walled portion 10b is T2, the minimum value of T1 / T2 is preferably 0.8 or less. The minimum value of T1 / T2 is the minimum value when T1 / T2 is calculated at each height position by moving the cross section along the height direction of the inner bag 4. The smaller the T1 / T2 ratio, the thinner the thin-walled portion 10a is compared to the thick-walled portion 10b, making the bottom portion 7 more likely to deform like an accordion. This value is preferably 0.1 or greater. If this value is too small, the thickness at the thin-walled portion 10a will be too small, making pinholes more likely to occur. This value is, for example, 0.1 to 0.8, specifically, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8, and may be within a range between any two of the values ​​exemplified here.

[0032] The mouth attachment member 8 is preferably configured to be attachable to the mouth 5, and configured so that the inner bag 4 rotates as the mouth attachment member 8 rotates (here, relative rotation with respect to the outer shell 3). With this configuration, it is possible to twist the inner bag 4 by rotating the mouth attachment member 8. Because the body 6 of the container body 2 has a larger outer diameter than the mouth 5, it is not easy to pull the inner bag 4 through the mouth 5 of the outer shell 3 simply by pulling the inner bag 4. However, by twisting the inner bag 4 and reducing the diameter of the body 6 of the inner bag 4, the body 6 of the inner bag 4 can more easily pass through the mouth 5 of the outer shell 3, and the inner bag 4 can be easily pulled out of the outer shell 3.

[0033] The engagement structure between the mouth-attached member 8 and the inner bag 4 will now be described in more detail.

[0034] 2 and 3, the inner bag 4 has a protruding portion 4c that protrudes from the open end 3a of the outer shell 3. The protruding portion 4c has a protruding tube 4c1, an engaging protrusion 4c2, an engaging flange 4c3, and an abutting flange 4c4.

[0035] The engaging protrusion 4c2 protrudes radially outward from the circumferential surface of the protruding tube 4c1. The engaging flange 4c3 is an annular portion located farther from the open end 3a than the engaging protrusion 4c2 and having a larger diameter than the protruding tube 4c1. The abutting flange 4c4 is an annular portion located at a position abutting the open end 3a and having a larger diameter than the protruding tube 4c1. The abutting flange 4c4 abuts against the open end 3a, thereby preventing the inner bag 4 from falling into the outer shell 3. Alternatively, the abutting flange 4c4 may be omitted and the engaging protrusion 4c2 may be abutted against the open end 3a to prevent the inner bag 4 from falling into the outer shell 3.

[0036] As shown in FIGS. 3 to 5, the mouth attachment member 8 includes an outer tube 8a, an intermediate tube 8b, an inner tube 8c, an engagement portion 8d, a claw portion 8e, a top plate 8f, and a nozzle 8g.

[0037] An engagement portion 8d is provided on the inner surface of the outer cylinder 8a. The engagement portion 8d is an engagement portion that engages with the engagement portion 5a of the mouth portion 5, and the mouth-mounted member 8 is attached to the mouth portion 5 by engaging the engagement portion 8d with the engagement portion 5a.

[0038] The intermediate cylinder 8b has a smaller diameter than the outer cylinder 8a and is disposed above the outer cylinder 8a. The inner cylinder 8c has a smaller diameter than the intermediate cylinder 8b and is a so-called inner ring that is disposed inside the outer cylinder 8a and the intermediate cylinder 8b. The upper surface of the intermediate cylinder 8b is covered with a top plate 8f. A nozzle 8g is provided on the top plate 8f.

[0039] Claws 8e are provided on the inner surface of the intermediate cylinder 8b. A plurality of claws 8e (eight in this embodiment) are provided and spaced apart in the circumferential direction. The number of claws 8e is, for example, 1 to 20, and preferably 4 to 12. Each claw 8e has an upper surface 8e1 and a lower inclined surface 8e2. A through hole 8h is provided in the top plate 8f at a position facing the claw 8e.

[0040] The mouth attachment member 8 having such a shape can be manufactured using a split mold that opens and closes in the vertical direction. Because the through-hole 8h and the upper surface 8e1 can be formed using the protrusions on the upper mold, the claws 8e can be formed without forcibly removing the lower mold. Therefore, it is not necessary to set the protrusion amount of the claws 8e to an amount that allows for forcible removal, and the protrusion amount can be set to an amount suitable for engagement with the inner bag 4 (e.g., 1 mm or more).

[0041] In this embodiment, the engaging portion 5a is a male threaded portion 5a1, and the engaging portion 8d is a female threaded portion 8d1 that can be threaded onto the male threaded portion 5a1. Therefore, the mouth attachment member 8 can be attached to the mouth 5 by rotating the mouth attachment member 8 relative to the mouth 5 in the tightening direction (usually clockwise when viewed from above) (hereinafter, relative rotation with respect to the mouth 5 will also be simply referred to as "rotation"). When the mouth attachment member 8 is rotated in the tightening direction, the female threaded portion 8d1 is threaded onto the male threaded portion 5a1 while the outer peripheral surface of the inner tube 8c shown in FIG. 4B is in close contact with the inner peripheral surface of the inner bag 4. At this time, friction between the outer peripheral surface of the inner tube 8c and the inner peripheral surface of the inner bag 4 causes the mouth 5 of the inner bag 4 to rotate together with the mouth attachment member 8, resulting in a twisting of the inner bag 4. Before the mouth-attaching member 8 is attached, the inner bag 4 is filled with contents, and if the inner bag 4 is twisted, the contents inside the inner bag 4 will spill out. To prevent this problem from occurring, the inner bag 4 and the outer shell 3 can be tightly fitted together at the mouth 5 to prevent the inner bag 4 from rotating relative to the outer shell 3. However, simply fitting them tightly together creates a new problem in that it becomes difficult to pull the inner bag 4 out of the outer shell 3.

[0042] Therefore, in this embodiment, a configuration is adopted in which the first resistance to relative rotation of the inner bag 4 in one direction relative to the outer shell 3 at the mouth 5 is greater than the second resistance to relative rotation in the other direction. For example, if the male thread portion 5a1 is a right-handed thread, the one direction and the other direction are the clockwise and counterclockwise directions, respectively, when viewed from above the container body 2. In other words, the one direction is the direction in which the mouth attachment member 8 is tightened, and the other direction is the direction in which the mouth attachment member 8 is loosened. With this configuration, the inner bag 4 is less likely to rotate relative to the outer shell 3 when attaching the mouth attachment member 8, thereby preventing the inner bag 4 from twisting when attaching the mouth attachment member 8. Furthermore, because the second resistance to relative rotation in the other direction is relatively small, when separating the inner bag 4 from the outer shell 3 after use, the inner bag 4 can be easily twisted and reduced in diameter by rotating the mouth 5 of the inner bag 4 relative to the outer shell 3 in the other direction, making it easy to pull the inner bag 4 out of the outer shell 3.

[0043] Specifically, the inner bag 4 and the outer shell 3 are engaged with each other at the opening 5, and this engagement is configured so that the first resistance is greater than the second resistance. More specifically, as shown in FIGS. 2C and 3B, the engagement is between a protrusion 4f provided on the outer peripheral surface of the inner bag 4 and a recess 3f provided on the inner peripheral surface of the outer shell 3. As shown in FIG. 2C, a tapered surface 4f1 is provided on the right side (loosening direction side) of the protrusion 4f to reduce the second resistance. On the other hand, no tapered surface is provided on the left side (tightening direction side) of the protrusion 4f. Therefore, at the opening 5, the resistance to rotating the inner bag 4 relative to the outer shell 3 in the tightening direction (first resistance) is greater than the resistance to rotating the inner bag 4 relative to the outer shell 3 in the loosening direction (second resistance). In this embodiment, two pairs of protrusions 4f and recesses 3f are provided at 180-degree intervals, but the number of pairs of protrusions 4f and recesses 3f may be one or three or more.

[0044] The second resistance may be reduced by providing a tapered surface in the recess 3f instead of or in addition to providing the tapered surface 4f1. Furthermore, the recess-recess engagement may be an engagement between a recess provided on the outer peripheral surface of the inner bag 4 and a protrusion provided on the inner peripheral surface of the outer shell 3. Furthermore, although the recess 3f is configured as a through-hole that penetrates the outer shell 3, it is sufficient that the recess 3f can engage with the protrusion 4f, and it is not necessary for the recess 3f to penetrate the outer shell 3.

[0045] As the mouth-mounting member 8 is further rotated in the tightening direction, the female thread portion 8d1 threads into the male thread portion 5a1, and the claw portion 8e gradually approaches the protruding portion 4c. At some point, the lower inclined surface 8e2 abuts against the engaging flange 4c3. If the mouth-mounting member 8 is further rotated in the tightening direction, the claw portion 8e overcomes the engaging flange 4c3, resulting in the state shown in FIG. 5. In this state, the claw portion 8e is positioned between the engaging flange 4c3 and the abutting flange 4c4. The engaging flange 4c3 is accommodated in the gap between the claw portion 8e and the top plate 8f. As shown in FIG. 5B, the protruding tube 4c1 is positioned between the claw portion 8e and the inner tube 8c. If the male thread portion 5a1 and the female thread portion 8d1 are not fully tightened at this point, the claw portion 8e will overcome the engaging protrusion 4c2, guided by the circumferential inclined surface 4c5 on the engaging protrusion 4c2, allowing the mouth-mounting member 8 to further rotate in the tightening direction. After the male screw portion 5a1 and the female screw portion 8d1 are fully tightened, the mouth portion attachment member 8 cannot rotate in the tightening direction and cannot move in the axial direction of the mouth portion 5.

[0046] In this state, the engaging protrusion 4c2 engages with the claw portion 8e of the mouth attachment member 8 in the rotational direction of the mouth attachment member 8, and the engaging flange 4c3 engages with the claw portion 8e of the mouth attachment member 8 in the axial direction of the mouth 5. In other words, the claw portion 8e engages with the engaging protrusion 4c2 and the engaging flange 4c3.

[0047] Therefore, when the mouth-attaching member 8 is rotated in the loosening direction (usually counterclockwise when viewed from above) after the contents inside the inner bag 4 have been used up, the inner bag 4 rotates in conjunction with the rotation of the mouth-attaching member 8. This causes the inner bag 4 to twist and reduce in diameter.

[0048] When the mouth attachment member 8 is further rotated in the loosening direction to release the engagement between the female thread portion 8d1 and the male thread portion 5a1, the mouth attachment member 8 becomes movable in a direction away from the open end 3a (i.e., in the axial direction of the mouth 5). Because the engagement flange 4c3 is engaged with the mouth attachment member 8 in the axial direction of the mouth 5, when the mouth attachment member 8 is moved in the axial direction of the mouth 5, the inner bag 4 also moves together with the mouth attachment member 8, and the inner bag 4 is pulled out of the outer shell 3.

[0049] As described above, according to the configuration of this embodiment, by simply rotating the mouth attachment member 8 in the loosening direction, the inner bag 4 is twisted and reduced in diameter, and then pulled out from the outer shell 3, making it possible to smoothly separate the inner bag 4 and the outer shell 3 with a simple operation.

[0050] 1-2. Manufacturing method of double container 1 As shown in Figures 9 to 12, the container body 2 can be formed by heating and biaxially stretching blow molding a preform 15 formed by covering an inner preform 14 that will become the inner bag 4 with an outer preform 13 that will become the outer shell 3.

[0051] As shown in Figure 9, the inner preform 14 is cylindrical and has a bottom, a mouth portion 14a, a body portion 14b, and a bottom portion 14c. A protrusion 14d is provided at the open end of the mouth portion 14a. The protrusion 14d does not deform during molding and remains in its original shape to become the protrusion 4c. Therefore, the matters described for the protrusion 4c also apply to the protrusion 14d. The bottom portion 14c is provided so as to close the lower end of the body portion 14b. A positioning pin 14c1 is provided on the bottom portion 14c.

[0052] 10, an uneven shape 19 is provided on the inner surface of the inner preform 14. The uneven shape 19 remains as it is or is stretched during molding to become the uneven shape 9 of the container body 2. The explanation regarding the uneven shape 9 also applies to the uneven shape 19 as long as it is not contrary to the spirit thereof.

[0053] As shown in Figures 9 and 10, an alternating thickness shape 20 is provided near the bottom 14c of the inner preform 14, in which thin sections 20a and thick sections 20b that are thicker than the thin sections 20a alternate in the circumferential direction. The alternating thickness shape 20 is stretched during biaxial stretch blow molding to form the alternating thickness shape 10. The number of thin sections 20a is, for example, 4 to 30, and preferably 10 to 20. The thin sections 20a are preferably provided in the longitudinal direction of the inner preform 14.

[0054] The thin-walled portion 20a can be formed by providing grooves 21 on one or both of the inner and outer surfaces of the inner preform 14. If grooves 21 are provided on the inner surface of the inner preform 14, grooves 11 will be formed on the inner surface of the inner bag 4 after molding. If grooves 21 are provided on the outer surface of the inner preform 14, grooves 11 will be formed on the outer surface of the inner bag 4 after molding, and grooves 11 will also be formed on the inner surface of the inner bag 4 at positions opposite the grooves 11 on the outer surface. This is because the resin at positions opposite the grooves 11 is pressed outward by the air pressure during blowing.

[0055] In a cross section perpendicular to the height direction of the inner preform 14 (such as the cross section in FIG. 10D ), the thickness of the inner bag 4 at the thin-walled portion 20a is t1, and the thickness of the inner preform 14 at the thick-walled portion 20b is t2. The minimum value of t1 / t2 is the minimum value obtained by moving the cross section along the height direction of the inner preform 14 and calculating t1 / t2 at each height position. The value of t1 / t2 correlates with T1 / T2, and T1 / T2 can be reduced by reducing t1 / t2. The value of t1 / t2 is preferably 0.1 or greater. This value is, for example, 0.1 to 0.8, specifically, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8, and may be within a range between any two of the values ​​exemplified here.

[0056] 9, 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 to close the lower end of the body portion 13b. The bottom portion 13c is provided with an annular protrusion 13d and a positioning hole (not shown).

[0057] 11, when forming the preform 15, the protrusion 14d is brought into contact with the open end of the mouth portion 13a, and the positioning pin 14c1 is inserted into the positioning hole. This positions the inner preform 14 and the outer preform 13 relative to each other. In this state, the mouth portion 14a faces the mouth portion 13a, and the body portion 14b faces the body portion 13b.

[0058] 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. The body portion 15b and the bottom portion 15c are primarily stretched in the biaxial stretch blow molding. However, since the biaxial stretch blow molding is performed with the annular convex portion 13d supported, the annular convex portion 13d and its inner region are hardly stretched during the biaxial stretch blow molding. The annular convex portion 13d becomes the annular convex portion 3b after molding.

[0059] When the preform 15 is heated and biaxially stretched and blow-molded, the inner surface of the preform 15 (i.e., the inner surface of the inner preform 14) is usually supported. The preform 15 can be conveyed upright, with the bottom 15c facing downward, or inverted, with the bottom 15c facing upward. Upright conveyance is common and preferred. However, conveying the preform 15 upright can cause a problem in that the outer preform 13 becomes detached from the inner preform 14 and falls off. While tightly fitting the outer preform 13 and the inner preform 14 together at the mouth 15a can prevent the outer preform 13 from falling off, this creates a new problem in that the inner bag 4 is difficult to detach from the outer shell 3 in the container body 2 obtained by molding.

[0060] Therefore, in this embodiment, in order to make it possible to easily pull out the inner bag 4 from the outer shell 3 after use while preventing the outer preform 13 from falling off, the inner preform 14 and the outer preform 13 are engaged with each other via a concave-convex structure at the mouth portion 15a.

[0061] In this embodiment, as shown in Fig. 11, the projections 14f provided on the outer peripheral surface of the mouth portion 14a of the inner preform 14 engage with recesses 13f provided on the inner peripheral surface of the mouth portion 13a of the outer preform 13. The projections 14f and recesses 13f correspond to projections 4f and recesses 3f, respectively. The projections 14f are provided with tapered surfaces 14f1, which correspond to 4f1. Therefore, the description of the projections 14f and recesses 13f also applies to the projections 4f and recesses 3f, provided that it does not contradict the spirit of the description, and the description of the projections 4f and recesses 3f also applies to the projections 14f and recesses 13f, provided that it does not contradict the spirit of the description.

[0062] As shown in Fig. 11, when the inner preform 14 is inserted into the outer preform 13, the convex portions 14f are inserted into the outer preform 13 while pushing apart the opening edge of the outer preform 13, and engage with the concave portions 13f. In order to reduce resistance during such engagement, a tapered surface 14f2 is provided on the lower side of the convex portions 14f (the side facing the outer preform 13). On the other hand, no tapered surface is provided on the upper side of the convex portions 14f. Therefore, after the convex portions 14f engage with the concave portions 13f, the engagement is difficult to release.

[0063] Instead of providing the tapered surface 14f2, or in addition to providing the tapered surface 14f1, a tapered surface may be provided on the opening edge of the outer preform 13 to reduce resistance when engaging the convex portion 14f with the concave portion 13f. Furthermore, the concave-convex engagement may be an engagement between a concave portion provided on the outer peripheral surface of the inner preform 14 and a convex portion provided on the inner peripheral surface of the outer preform 13. Furthermore, although the concave portion 13f is configured as a through hole penetrating the outer preform 13, it is sufficient that the concave portion 13f be able to engage with the convex portion 14f, and it is not necessary for the concave portion 13f to penetrate the outer preform 13.

[0064] The inner preform 14 and the outer preform 13 can be formed by direct blow molding, injection molding, or the like using thermoplastic resins such as polyester (e.g., PET) or polyolefin (e.g., polypropylene, polyethylene). The inner preform is preferably made of a material with a higher molding shrinkage rate than the outer preform. In this case, a gap is formed between the outer shell 3 and the inner bag 4 due to molding shrinkage, making it easier to introduce outside air into the intermediate space between the outer shell 3 and the inner bag 4.

[0065] In one example, the inner preform 14 is made of polyolefin (e.g., polypropylene), and the outer preform 13 is made of PET. Polyolefin has a larger molding shrinkage rate than PET, so using such a resin configuration makes it easier for a gap to form between the outer shell 3 and the inner bag 4. Furthermore, by making the inner preform 14 and the outer preform 13 from different materials, welding to each other during blow molding is suppressed.

[0066] Furthermore, if the mouth 14a of the inner preform 14 is made of polyolefin and the mouth 13a of the outer preform 13 is made of amorphous PET, heating the mouth 13a during biaxially stretched blow molding promotes crystallization of the amorphous PET, resulting in a reduction in the dimensions of the mouth 13a. While the mouth 14a is also heated, polyolefin is a crystalline resin, and since it has already crystallized to some extent prior to biaxially stretched blow molding, its dimensional change during biaxially stretched blow molding is smaller than that of amorphous PET. As a result, shrinkage of the mouth 13a becomes more significant than shrinkage of the mouth 14a, forming a gap between the protruding portion 14d of the inner preform 14 and the opening edge of the outer preform 13, which may interfere with clamping the preform 15 between a pair of split molds. Furthermore, the container body 2 obtained after molding may have a gap between the protruding portion 4c of the inner bag 4 and the opening edge 3a of the outer shell 3, as shown in FIG. 3A, which may result in a poor appearance. However, in this embodiment, the inner preform 14 and the outer preform 13 are engaged with each other at the mouth portion 15a, and the inner bag 4 and the outer shell 3 are also engaged at the mouth portion 5, thereby preventing the occurrence of the gap.

[0067] The inner preform 14 is preferably formed by direct blow molding. Direct blow molding (blow molding using a molten cylindrical parison) makes it easy to form the inner preform 14 with a laminated structure. The outer preform 13 is preferably formed by injection molding.

[0068] After the preform 15 is biaxially stretched and blow-molded, an outside air inlet hole 16 is formed in the outer shell 3 to obtain the container body 2 shown in Fig. 1. Thereafter, the inner bag 4 is filled with the contents, and then the mouth attachment member 8 is attached to the mouth 5 to obtain the double container 1.

[0069] 2. Second embodiment A second embodiment of the present invention will be described with reference to Fig. 2. This embodiment is similar to the first embodiment, and the following description will focus on the differences.

[0070] In this embodiment, as shown in FIG. 13, the recess 3f is formed by a groove 3f1. The groove 3f1 extends between an end 3f2 on the open end 3a side of the outer shell 3 and an end 3f3 on the inside of the outer shell 3. The protrusion 4f shown in FIG. 2C is disposed within the groove 3f1, and the engagement between the protrusion 4f and the recess 3f can be released by moving the protrusion 4f along the groove 3f1 toward the end 3f2. This configuration significantly reduces the second resistance. Furthermore, once the protrusion 4f reaches the end 3f2, it cannot be moved further along the groove 3f1 toward the inside of the outer shell 3, and therefore the first resistance significantly increases.

[0071] The inclination angle of groove 3f1 preferably matches the inclination angle of the threads of male thread portion 5a1. In this case, when opening attachment member 8 and inner bag 4 are rotated together in the loosening direction, convex portion 4f can be moved smoothly along groove 3f1.

[0072] The recess 3f formed by the groove 3f1 can be obtained by forming the recess 13f of the outer preform 13 as a groove. In this case, the protrusion 14f and the recess 13f can be engaged by moving the protrusion 14f of the inner preform 14 along the groove, so resistance during engagement of the protrusions and recesses is extremely small. If the groove of the outer preform 13 extends in the direction of the central axis of the mouth portion 13a of the outer preform 13, the outer preform 13 will easily fall off from the inner preform 14. Therefore, it is preferable that the groove forming the recess 13f extend in a direction inclined with respect to the central axis of the mouth portion 13a of the outer preform 13.

[0073] Here, we have given an example of a case where the outer shell 3 or the outer preform 13 has a recess, but even if the inner bag 4 or the inner preform 14 has a recess, it is possible to make this recess into a groove and obtain the same effect as above.

[0074] 3. Inventions from a different perspective From the viewpoint of preventing the outer preform 13 from falling off even when the preform 15 is transported upright during the biaxial stretch blow molding process, and preventing a gap from occurring between the protruding portion 14d of the inner preform 14 and the outer preform 13, the following inventions can be extracted.

[0075] A method for manufacturing a double-layered container comprising a biaxially stretched blow molding process, In the biaxially stretched blow molding step, a container body is formed by heating a preform formed by covering an outer preform with an inner preform and biaxially stretching and blow molding the preform, The method wherein the inner preform and the outer preform are engaged in a protruding and recessing engagement at the mouth of the preform.

[0076] In the container body 2 obtained by the method of this aspect, it is not essential that the first resistance to relative rotation in one direction of the inner bag 4 relative to the outer shell 3 at the mouth portion 5 is greater than the second resistance to relative rotation in the other direction.

[0077] 4. Other embodiments In the above embodiment, the outside air introduction holes 16 are formed after biaxially stretch blow molding, but through holes that serve as outside air introduction holes may be formed in the outer preform 13 in advance. The air inlet 16 may be formed at the bottom of the outer shell 3 . In the present invention, the structure for twisting the inner bag 4 is not particularly limited, and the inner bag 4 does not have to be configured to rotate in conjunction with the rotation of the opening attachment member 8. In this case, for example, the inner bag 4 may be rotated by pinching it with fingers. Therefore, a cap or pump that does not have a structure for engaging with the inner bag 4 may be used as the opening attachment member 8. Furthermore, the container body 2 does not have to have the protrusion 4c. For example, instead of the protrusion 4c, a flange may be provided at the open end of the inner bag 4, and this flange may be abutted against the open end of the outer shell 3, thereby preventing the inner bag 4 from falling out into the outer shell 3. In the above embodiment, the alternating thickness shapes 10, 20 are realized by forming the recessed ribs 11, 21. However, the alternating thickness shapes 10, 20 may also be formed by forming protruding ribs on one or both of the inner and outer surfaces of the inner bag 4 or the inner preform 14 to form thick portions. Even in this case, the thin portions are selectively bent as the inner bag 4 twists, so the bottom 7 is easily deformed into an accordion-like shape and reduced in diameter. Furthermore, the alternating thickness shapes 10, 20 may be omitted if unnecessary. The uneven shape 9 may be omitted if not required. The annular protrusions 3b and 13d can be omitted.

[0078] 5. Additional Notes The original claims of the original application are as follows: [1] A double container comprising a container body, the container body comprising a mouth, a body, and a bottom, the mouth being a cylindrical portion having an open end, the body being disposed adjacent to the mouth on a side farther from the open end than the mouth and having a larger outer diameter than the mouth, the bottom being configured to close the lower end of the body, the container body comprising an inner bag and an outer shell disposed to cover the inner bag, and a first resistance to relative rotation of the inner bag relative to the outer shell in one direction at the mouth being greater than a second resistance to relative rotation in the other direction. [2] A double container as described in [1], wherein the opening has a male threaded portion that is a right-handed thread, and the one direction and the other direction are clockwise and counterclockwise, respectively, when viewed from the top of the container body. [3] A double container as described in [1] or [2], comprising a mouth attachment member, the mouth attachment member having a female thread portion that can be threaded into the male thread portion of the mouth, the one direction being the tightening direction of the mouth attachment member, and the other direction being the loosening direction of the mouth attachment member. [4] A double container according to any one of [1] to [3], wherein the inner bag and the outer shell are engaged with each other at the mouth, and the engagement is configured so that the first resistance is greater than the second resistance. [5] A double container according to [4], wherein the concave-convex engagement is an engagement between a convex portion provided on the outer peripheral surface of the inner bag and a concave portion provided on the inner peripheral surface of the outer shell. [6] A double container according to any one of [1] to [5], wherein the recessed portions of the concave-convex engagement are formed as grooves, and the concave-convex engagement can be released by moving the convex portions of the concave-convex engagement along the grooves. [7] A double container according to [6], wherein the inclination angle of the groove matches the inclination angle of the thread of the male screw portion provided in the mouth portion. [8] A method for manufacturing a double-layered container comprising a biaxially stretched blow molding process, wherein in the biaxially stretched blow molding process, a preform formed by covering an outer preform on an inner preform is heated and biaxially stretched blow molded to form a container body, and the inner preform and the outer preform are engaged with each other at the mouth of the preform. [Explanation of symbols]

[0079] 1:Double container 2: Container body 3: Outer shell 3a: Open end 3b: Annular convex part 3c: Through hole 3f: Recess 3f1: Groove 3f2: Edge 3f3: Edge 4: Inner bag 4c:Protrusion 4c1:Protruding tube 4c2: Engagement protrusion 4c3: Engagement flange 4c4: Abutting flange 4c5: Circumferential slope 4d: side 4e: Protrusion 4f: Convex part 4f1: Tapered surface 5: Mouth 5a: Engagement part 5a1: Male thread 5b: Flange 5c: Open end 6: Body 6b:Shoulder 6c: Body 6d: Recess 6e: Groove 7: Bottom 7a: Bottom concave area 7a1: Peripheral surface 7a2: Bottom 7b: Peripheral area 8: Mouth attachment member 8a: Outer cylinder 8b: Intermediate cylinder 8c: Inner cylinder 8d: Engagement part 8d1: Female thread 8e: Claw part 8e1:Top surface 8e2: Lower slope 8f: Top board 8g: Nozzle 8h: Through hole 9: Uneven shape 9a: Concave 9b: Convex strip 10: Alternating thickness shape 10a: Thin section 10b: Thick wall part 11: Groove 13: Outer preform 13a: Mouth 13b: Torso 13c: Bottom 13d: Annular convex part 13f: Recess 14: Inner preform 14a: Mouth 14b: Torso 14c: Bottom 14c1: Locating pin 14d:Protrusion 14f: Convex part 14f1: Tapered surface 14f2: Tapered surface 15: Preform 15a: Mouth 15b: Body 15c: bottom 16: Outside air intake 19: Uneven shape 20: Alternating thickness shape 20a: Thin section 20b: Thick wall part 21: Groove

Claims

1. A double container comprising a container body and a mouth attachment member, the container body includes a mouth, a body, and a bottom, the mouth being a cylindrical portion having an open end, the body being disposed adjacent to the mouth on a side farther from the open end than the mouth, and having a larger outer diameter than the mouth, and the bottom being configured to close the lower end of the body, The container body includes an inner bag and an outer shell disposed to cover the inner bag, the opening attachment member has a female thread portion that can be threaded into a male thread portion of the opening of the container body, The double container is configured to be able to prevent the inner bag from twisting when the opening attachment member is rotated in one direction, The one direction is a tightening direction of the mouth attachment member.

2. The double container according to claim 1, the container body is a biaxially stretched blow molded article, The body portion has a shoulder portion whose outer diameter increases as it moves away from the mouth portion, The double container, wherein the inner bag and the outer shell abut at any one of the shoulder portion, the body portion, and the bottom portion.

3. The double container according to claim 2, A double container, wherein the outer surface of the inner bag and the inner surface of the outer shell have the same inclination angle at the shoulder portion.

4. The double container according to any one of claims 1 to 3, the inner bag includes a plurality of circumferentially spaced engagement projections; The mouth attachment member includes a plurality of claws spaced apart in the circumferential direction, The double container has an engaging projection on the inner bag and a claw portion on the spout attachment member engaging with each other in the circumferential direction, thereby engaging the inner bag with the spout attachment member in the circumferential direction.

5. The double container according to any one of claims 1 to 4, The inner bag is configured to rotate in accordance with the rotation of the mouth attachment member.

6. The double container according to any one of claims 1 to 5, The inner bag has a cylindrical shape at the entire portion facing the mouth of the outer shell.

7. The double container according to any one of claims 1 to 6, A double container, wherein the bottom of each of the inner bag and the outer shell is provided with a bottom recessed area and a peripheral area surrounding the bottom recessed area.

8. The double container according to claim 7, A double container, wherein the thicknesses of the inner bag and the outer shell gradually decrease around the periphery of the bottom recessed region as they approach the peripheral region.

9. The double container according to claim 8, The double container, wherein the peripheral surface is an inclined surface that slopes away from the center of the bottom toward the peripheral region.

10. The double container according to any one of claims 7 to 9, The bottom of the inner bag is provided with an alternating thickness shape in which thin portions and thick portions that are thicker than the thin portions appear alternately in the circumferential direction, The double container, wherein the alternating thickness shape is provided on at least one of the peripheral surface of the bottom recessed region and the peripheral region.

11. The double container according to claim 10, The thin-walled portion is formed by providing a groove on one or both of the inner surface and the outer surface of the inner bag.

12. The double container according to any one of claims 1 to 11, A double container configured so that the inner bag does not shrink when the contents of the inner bag are discharged.

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