JP7804170B2 - double container - Google Patents

Description

The present invention relates to a double container.

Double containers with a container body having an outer shell and an inner bag are known. For example, Patent Document 1 discloses a double container formed by biaxially stretching blow molding an outer shell preform and an inner bag preform in a stacked state.

JP 2019-10741 A

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

The outer shell and inner bag can be separated by the user pulling the inner bag from the outer shell, and it is desirable to reduce the force required to pull out the inner bag.

The present invention was made in light of these circumstances, and provides a double-layered container that reduces the force required to pull out the inner bag.

The present invention provides a double container comprising a container body having an inner bag and an outer shell, the container body comprising a mouth, a body, and a bottom, the mouth being a cylindrical portion with 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 body having a curved portion that curves outward, and where D is the diameter of the container body at the portion with the smallest radius of curvature at the curved portion and R is the radius of curvature, R/D is 0.5 or greater.

In conventional double-layered containers, the barrel of the container body has a curved section with a small radius of curvature, and the inner bag is pressed strongly against the outer shell near this curved section, requiring a large amount of force to pull out the inner bag. In this embodiment, the R/D ratio is 0.5 or greater, resulting in a gentle curved section, which prevents the inner bag from being pressed against the outer shell near the curved section, reducing the force required to pull out the inner bag.

Various embodiments of the present invention will be described below as examples, and the embodiments shown below can be combined with each other.
Preferably, the double container described above is a double container in which the body portion has a shoulder portion whose outer diameter increases as it moves away from the mouth portion, and the shoulder portion has an inclination angle of 25 degrees or less with respect to the central axis of the mouth portion.
Preferably, the double container described above is a double container in which, when the inner diameter of the mouth of the outer shell is D2, D/D2 is 1.8 or less.
Preferably, in the double container described above, the body portion is provided with a tapered portion, the diameter of which is tapered toward the bottom, closer to the bottom than the curved portion.
Preferably, the double container described above is a double container in which, when the diameter of the bottom surface of the recess provided in the bottom portion is D3 and the inner diameter of the mouth portion of the outer shell is D2, D3/D2 is 0.6 or less.

Fig. 1A is a perspective view of a double container 1 according to a first embodiment of the present invention, showing a state in which the mouth attachment member 8 is separated from the container body 2. Fig. 1B is an enlarged view of region B in Fig. 1A. The dashed-dotted line in the figure indicates the boundary line where the curvature of the surfaces constituting the surface shape changes. This is also true for the other figures. 1 is a cross-sectional view passing through the central axis C of the mouth portion 5 of the container body 2 and the centers of the two recesses 3f. 3A is an enlarged view of region A in FIG. 2, and FIG. 3B is an enlarged view of region B in FIG. 4A-4C are end views taken along planes AC in FIG. 3A, respectively. 5A to 5F are a front view, a plan view, a bottom view, a right side view, a left side view, and a rear view of the container body 2, respectively. 6A is a perspective view of the mouth-mounted member 8 with a portion cut away, and FIG. 6B is a perspective view of the mouth-mounted member 8 as seen obliquely from below. FIG. 2 is a front view of the spout attachment member 8 attached to the container body 2. 8A and 8B are end views taken along planes A and B in FIG. 7, respectively. FIG. 2 is a perspective view showing a state in which the inner preform 14 and the outer preform 13 are separated. FIG. 1 is a perspective view of the inner preform 14 as seen obliquely from above. FIG. 1 is a perspective view of a preform 15 formed by covering an outer preform 13 on an inner preform 14.

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 independent invention.

1. First embodiment 1-1. Configuration of double container 1 <Basic configuration>
As shown in FIG. 1, a double container 1 according to a first embodiment of the present invention comprises a container body 2 and a spout attachment member 8 .

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 engaging portion 5a to which a mouth attachment member 8, such as a cap or pump, can be attached. The engaging portion 5a is a male thread portion 5a1 if the mouth attachment member 8 is a screw-type, or is an annular protrusion protruding in the circumferential direction if the mouth attachment member 8 is a stopper-type. The mouth attachment member 8 may or may not have a check valve (not shown). 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.

The body 6 is positioned adjacent to the mouth 5, farther from the open end 5c than the mouth 5. The body 6 has a larger outer diameter (in this specification, "outer diameter" refers to 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 located 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 with a substantially constant outer diameter, located closer to the bottom 7 than the shoulder 6b.

As shown in FIG. 3A, 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 the protruding portion 4c. 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.

The thickness of the outer shell 3 at the center of the height of the container body 2 is, for example, 0.2 to 0.8 mm, with 0.25 to 0.5 mm being preferable. Specific examples of this thickness include 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8 mm, and may fall within a range between any two of the values exemplified here. The thickness of the inner bag 4 at the center of the height of the container body 2 is, for example, 0.05 to 0.25 mm, with 0.08 to 0.20 mm being preferable. Specific examples of this thickness include 0.05, 0.08, 0.10, 0.15, 0.20, and 0.25 mm, and may fall within a range between any two of the values exemplified here.

If the mouth attachment member 8 does not have a check valve, the inner bag 4 does not shrink even after the contents of the inner bag 4 are dispensed, making it difficult to pull out the inner bag 4 through the mouth 5 of the outer shell 3. The present invention makes it easy to pull out the inner bag 4 through the mouth 5 of the outer shell, so the significance of applying the present invention is particularly evident when the mouth attachment member 8 does not have a check valve.

The inner diameter D2 of the mouth 5 of the outer shell 3 is, for example, 20 to 50 mm, preferably 25 to 40 mm. The outer diameter D4 of the mouth 5 of the outer shell 3 is, for example, 25 to 55 mm, preferably 30 to 45 mm. Specific examples of the inner diameter D2 are 20, 25, 30, 35, 40, 45, or 50 mm, and the inner diameter D4 is, for example, 25, 30, 35, 40, 45, 50, or 55 mm, each of which may be within a range between any two of the values exemplified here. The length of the mouth 5 is, for example, 15 to 35 mm, for example, 15, 20, 25, 30, or 35 mm, and may be within a range between any two of the values exemplified here.

As shown in Figure 3A, the body 6 has a curved portion 6d that curves outward. The curved portion 6d is located at or near the boundary between the shoulder portion 6b and the body main body 6c. If the diameter of the container body 2 at portion 6d1 where the radius of curvature of the curved portion 6d is smallest is D and the radius of curvature at portion 6d1 is R, then it is preferable that R/D be 0.5 or greater (0.73 in this embodiment). The larger this value, the greater the ratio of the radius of curvature R to the diameter D, resulting in a more gradual curve of the curved portion 6d. This prevents the inner bag 4 from being pressed against the outer shell 3 near the curved portion 6d, reducing the force required to pull out the inner bag 4. R/D is, for example, 0.5 to 2, and specifically, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0, and may be within a range between any two of the numerical values exemplified here, or any value equal to or greater than the range.

It is also preferable that D/D2 be 1.8 or less (1.4 in this embodiment). The smaller this value, the easier it is for the curved portion 6d to pass through the opening 5, thereby reducing the force required to pull out the inner bag 4. D/D2 is, for example, 1.1 to 1.8, and more specifically, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.8, and may be within a range between any two of the values exemplified here.

The inclination angle α of the shoulder portion 6b relative to the central axis of the opening is preferably 25 degrees or less (19 degrees in this embodiment). The smaller this inclination angle α, the less the inner bag 4 is pressed against the outer shell 3 near the curved portion 6d, reducing the force required to pull out the inner bag 4. The inclination angle α is, for example, 5 to 25 degrees, and more specifically, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 degrees, and may be within a range between any two of the values listed here or less than any of the values listed here.

As shown in FIG. 1, the body 6 has a tapered portion 6e, which is closer to the bottom 7 than the curved portion 6d and tapers toward the bottom 7. The tapered portion 6e has a shape that functions as a so-called "pull-out taper," and providing the tapered portion 6e reduces the force required to pull out the inner bag 4. In this embodiment, the body main body 6c has a shape that tapers toward the bottom 7, so the entire body main body 6c forms the tapered portion 6e. However, for example, a portion of the body main body 6c may not taper in diameter, and the remaining portion of the body main body 6c may taper in diameter. It is preferable that the portion that does not taper in diameter is a portion where the outer diameter does not change.

<Uneven shape 9 on the inner surface of the mouth portion 5>
As shown in Figure 4C, 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, preferably 10 to 20. The grooves 9a and protrusions 9b preferably extend non-parallel in the circumferential direction of the mouth 5. The extending direction of the grooves 9a and protrusions 9b is preferably 0 to 60 degrees, 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 of 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 making the recesses 9a thinner or by making the protrusions 9b thicker than other parts of the mouth 5 of the inner bag 4, or by making the recesses 9a thinner and the protrusions 9b thicker.

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 more easily transmitted to the ridges 9b than to the recesses 9a, and the ridges 9b rotate faster than the recesses 9a. As a result, creases are formed 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 recessed and raised 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 a recessed or raised surface on the outer surface of the inner bag 4. If a recessed or raised surface is provided on the outer surface of the inner bag 4, the inner bag 4 and outer shell 3 will engage 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.

Let T be the thickness of the inner bag 4 at the ridge 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 apex of the ridge 9b), and let D be the depth of the recess 9a (the radius of the inscribed circle passing through the bottom of the recess 9a minus the radius of the inscribed circle passing through the apex of the ridge 9b). The maximum value of D/T is, for example, 0.2 to 0.8, with 0.3 to 0.5 being preferable. 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 given here. The thickness of the inner bag 4 at the mouth portion 5 other than the uneven 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 recessed ribs 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.

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, or 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, or may be within a range between any two of the numerical values exemplified here.

<Structure of bottom 7>
As shown in Figure 3B, 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 are hardly stretched during biaxial stretch blow molding, so the wall thickness of both the outer shell 3 and the inner bag 4 is large. The annular protrusion 3b can be omitted.

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, and more preferably 0.6 or less. Because the thickness of the inner bag 4 increases at the annular protrusion 3b and its inner region, the smaller D1/D2 is, the more easily the bottom portion 7 of the inner bag 4 can be reduced in diameter. 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. It may be within a range between any two of the values exemplified here, or any value less than or equal to any of them.

The bottom 7 of the container body 2 (i.e., the bottoms 7 of the inner bag 4 and 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 an area of the bottom 7 recessed toward the inside of the container body 2. The peripheral region 7b forms the contact surface of the container body 2. As shown in Figure 3B, at the peripheral surface 7a1 of the bottom recessed region 7a, the thickness of the inner bag 4 and outer shell 3 gradually decreases 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 approximately flat. As a result, the bottom recessed region 7a has a substantially truncated cone shape.

The bottom surface 7a2 of the bottom recessed region 7a is difficult to stretch during biaxial stretch blow molding and tends to have a large wall thickness. Therefore, the smaller the diameter D3 of the bottom surface 7a2 (in other words, the diameter of the area surrounded by the boundary line 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, and more preferably 0.6 or less. D3/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. It may be within a range between any two of the values exemplified here, or any value less than the range.

<Design>
The container body 2 has a novel aesthetic appearance. The design of the container body 2 shown in Figure 5 can be understood as an overall design, and the area A can also be understood as the "portion for which a design registration is sought as a partial design," the area B can also be understood as the "portion for which a design registration is sought as a partial design," and the other portions can also be understood as the "portion for which a design registration is sought as a partial design." For convenience, areas A and B are shown only in the front view, but it is intended that the entire periphery of the container body 2 be the "portion for which a design registration is sought as a partial design."

In the bottom 7, area C, which includes the bottom recessed area 7a, may or may not be included in the "portion for which a design registration is sought as a partial design."

<Engagement Structure Between Mouth Attachment Member 8 and Inner Bag 4, and Engagement Structure Between Inner Bag 4 and Mouth 5 of Outer Shell 3>
The mouth attachment member 8 is preferably configured to be attachable to the mouth 5, and configured so that the inner bag 4 rotates in conjunction with rotation of the mouth attachment member 8 (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, making it easier to pull the inner bag 4 out of the outer shell 3.

The engagement structure between the mouth attachment member 8 and the inner bag 4 is explained in more detail below.

As shown in FIG. 1, 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.

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

As shown in Figure 6, the nozzle attachment member 8 includes an outer tube 8a, an inner tube 8c, an engaging portion 8d, a claw portion 8e, a top plate 8f, and a discharge port 8g.

The outer surface of the outer tube 8a is provided with an uneven pattern in which protrusions and recesses alternate in the circumferential direction. This makes it easy to rotate the mouth attachment member 8. An engagement portion 8d is provided on the inner surface of the outer tube 8a. The engagement portion 8d engages with the engagement portion 5a of the mouth 5, and the mouth attachment member 8 is attached to the mouth 5 by engaging the engagement portion 8d with the engagement portion 5a.

The upper surface of the outer cylinder 8a is covered with a top plate 8f. The top plate 8f is provided with an outlet 8g. A nozzle may be provided in the outlet 8g. The inner cylinder 8c has a smaller diameter than the outer cylinder 8a and is a so-called inner ring that is placed inside the outer cylinder 8a.

Claws 8e are provided on the inner surface of the outer cylinder 8a. Multiple 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. Through holes 8h are provided in the top plate 8f at positions opposite the claws 8e.

A mouth attachment member 8 of this shape can be manufactured using a split mold that opens and closes vertically. The through-hole 8h and the upper surface 8e1 of the claw portion 8e can be formed using a protrusion on the upper mold, so the claw portion 8e can be formed without forcibly removing the lower mold. Therefore, the protrusion amount of the claw portion 8e does not need to be set to an amount that allows for forcible removal, and can be set to an amount that is suitable for engagement with the inner bag 4 (e.g., 1 mm or more).

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 spout attachment member 8 can be attached to the spout 5 by rotating it relative to the spout 5 in the tightening direction (typically clockwise when viewed from above). (Hereinafter, relative rotation with respect to the spout 5 will also be simply referred to as "rotation"). When the spout attachment member 8 is rotated in the tightening direction, the female threaded portion 8d1 threads onto the male threaded portion 5a1 while the outer surface of the inner tube 8c shown in FIG. 8A is in close contact with the inner surface of the inner bag 4. At this time, friction between the outer surface of the inner tube 8c and the inner surface of the inner bag 4 causes the spout 5 of the inner bag 4 to rotate together with the spout attachment member 8, twisting the inner bag 4. Before the mouth attachment 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 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: it becomes difficult to pull the inner bag 4 out of the outer shell 3.

Therefore, in this embodiment, a configuration is adopted in which the first resistance to relative rotation of the inner bag 4 relative to the outer shell 3 in one direction 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, respectively, clockwise and counterclockwise when viewed from the top of 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.

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 FIG. 4B , the engagement is between a convex portion 4f on the outer surface of the inner bag 4 and a concave portion 3f on the inner surface of the outer shell 3. As shown in FIG. 4B , the outer shell 3 has a protrusion 3g that protrudes inward on the clockwise side (tightening direction) of the convex portion 4f, whereas no such protrusion is provided on the counterclockwise side (loosening direction) of the convex portion 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 convex portions 4f and concave portions 3f are provided at 180-degree intervals, but the number of pairs of convex portions 4f and concave portions 3f may be one, three, or more.

The concave-convex engagement may also be achieved by engaging a concave portion on the outer peripheral surface of the inner bag 4 with a convex portion on the inner peripheral surface of the outer shell 3. Furthermore, while the concave portion 3f is configured as a through-hole that penetrates the outer shell 3, the concave portion 3f need not penetrate the outer shell 3 as long as it can engage with the convex portion 4f.

When the mouth-mounting member 8 is further rotated in the tightening direction, the female thread portion 8d1 threads into the male thread portion 5a1, while the claw portion 8e gradually approaches the protruding portion 4c. At some point, the inclined surface on the underside of the claw portion 8e abuts the engaging flange 4c3 shown in Figure 1B. In this state, when the mouth-mounting member 8 is further rotated in the tightening direction, the claw portion 8e overcomes the engaging flange 4c3, reaching the state shown in Figure 8A. 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 Figure 8A, 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 be guided by the circumferentially inclined surface 4c5 on the engagement protrusion 4c2 and will climb over the engagement protrusion 4c2, allowing the mouth attachment member 8 to further rotate in the tightening direction. After the male thread portion 5a1 and the female thread portion 8d1 are fully tightened, the mouth attachment member 8 will no longer be able to rotate in the tightening direction and will no longer be able to move in the axial direction of the mouth portion 5.

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 portion 5. In other words, the claw portion 8e engages with the engaging protrusion 4c2 and the engaging flange 4c3.

For this reason, when the contents of the inner bag 4 are used up, the opening attachment member 8 is rotated in the loosening direction (usually counterclockwise when viewed from above), and the inner bag 4 rotates in conjunction with the rotation of the opening attachment member 8. This causes the inner bag 4 to twist and shrink in diameter.

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

As described above, with the configuration of this embodiment, simply by 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 outer shell 3 with a simple operation.

<Loosening prevention structure of the mouth attachment member 8>
In this embodiment, the container body 2 has a multiple-start thread (more specifically, a triple-start thread) for the male thread portion 5a1 and the female thread portion 8d1, which makes them prone to loosening even after tightening. Therefore, as shown in FIG. 8B , a locking structure 24 is provided to prevent loosening of the threaded engagement between the mouth 5 and the mouth attachment member 8. In this embodiment, the locking structure 24 is composed of a protrusion 3i protruding from the outer peripheral surface of the outer shell 3 and a protrusion 8i protruding from the inner peripheral surface of the outer tube 8a of the mouth attachment member 8. The protrusions 3i and the protrusions 8i are each provided in multiple numbers (three in this embodiment), preferably evenly spaced apart in the circumferential direction. The locking structure 24 may also have a different configuration for circumferentially engaging the mouth 5 and the mouth attachment member 8. For example, the protrusions 3i may be engaged with a recess provided on the inner peripheral surface of the outer tube 8a of the mouth attachment member 8.

<Protrusion 3h on the inner surface of the mouth portion 5 of the outer shell 3>
As shown in Figure 4A, a protrusion 3h is provided on the inner surface of the mouth portion 5 of the outer shell 3, closer to the opening end 3a than the protrusion 3g. The protrusion 3h is preferably provided so as to connect to the protrusion 3g. The mouth portion 5 of the outer shell 3 is thinned at the locations where the protrusions 3g and 3h are provided, so that the outer shell 3 abuts the inner bag 4 only at the protrusions 3g and 3h. This reduces the contact area between the outer shell 3 and the inner bag 4, thereby reducing the force required to pull out the inner bag 4. The protrusions 3g and 3h are provided at multiple locations (two locations in this embodiment) circumferentially, preferably spaced apart at equal intervals. This makes it possible to maintain the mouth portion 5 of the outer shell 3 and the mouth portion 5 of the inner bag 4 concentrically.

When the mouth attachment member 8 is rotated in the loosening direction, the threaded engagement between the mouth attachment member 8 and the mouth 5 is released after approximately half a turn. Once this threaded engagement is released, the inner bag 4 can be pulled out of the outer shell 3. However, this can create a problem in that the user may not immediately realize that the threaded engagement has been released, causing the mouth attachment member 8 to continue to spin freely. In contrast, in this embodiment, when the protrusion 4f is rotated in the loosening direction (counterclockwise in Figures 4A and 4B), it reaches the protrusion 3h after approximately half a turn (for example, the protrusion 4f on the right side in Figure 4B reaches the protrusion 3h on the left side in Figure 4A), preventing further rotation of the inner bag 4. This configuration allows the inner bag 4 to be pulled out at the point when it no longer rotates when the mouth attachment member 8 is rotated in the loosening direction, thereby enabling the inner bag 4 to be pulled out at the appropriate time, improving usability.

1-2. Manufacturing Method of Double Container 1 As shown in Figures 9 to 11, the container body 2 can be formed by heating a preform 15 and biaxially stretching and blow molding it.

<Configuration of the inner preform 14, outer preform 13, and preform 15>
In one example, the preform 15 can be constructed 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 .

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

As shown in Figure 10, the inner surface of the inner preform 14 has an uneven shape 19. The uneven shape 19 remains as 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, unless it contradicts the intent of the explanation.

As shown in FIG. 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). The mouth portion 13a of the outer preform 13 is provided with a protrusion 13h that becomes protrusion 3h, a protrusion (not shown) that becomes protrusion 3g, and a protrusion 13i that becomes protrusion 3i.

As shown in Figure 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.

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 during biaxial stretch blow molding. However, because biaxial stretch blow molding is performed while the annular convex portion 13d is supported, the annular convex portion 13d and its inner region are hardly stretched during biaxial stretch blow molding. The annular convex portion 13d becomes the annular convex portion 3b after molding.

<Engagement of the Inner Preform 14 and the Outer Preform 13 at the Mouth Portion 15a>
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. Conveying the preform 15 upright can cause the outer preform 13 to become detached from the inner preform 14. 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 the container body 2 obtained by molding: the inner bag 4 is difficult to detach from the outer shell 3.

In this embodiment, therefore, to prevent the outer preform 13 from falling out while allowing the inner bag 4 to be easily pulled out of the outer shell 3 after use, the inner preform 14 and the outer preform 13 are engaged with each other via a concave-convex structure at the opening 15a.

In this embodiment, as shown in Figure 9, the concave-convex engagement is an engagement between a convex portion 14f provided on the outer peripheral surface of the mouth portion 14a of the inner preform 14 and a concave portion 13f provided on the inner peripheral surface of the mouth portion 13a of the outer preform 13. The convex portion 14f and the concave portion 13f become the convex portion 4f and the concave portion 3f, respectively.

<Materials and manufacturing method of the inner preform 14 and the outer preform 13>
The inner preform 14 and the outer preform 13 can be formed by direct blow molding, injection molding, or the like using a thermoplastic resin such as polyester (e.g., PET) or polyolefin (e.g., polypropylene, polyethylene), etc. In one example, the inner preform 14 is made of polyolefin (e.g., polypropylene), and the outer preform 13 is made of PET.

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.

The preform 15 may be formed by forming the inner preform 14 and the outer preform 13 separately and then combining them, or it may be formed by two-color molding.

2. Other Embodiments The container body 2 may be formed by a method other than biaxially stretched blow molding, for example, by direct blow molding, which forms a laminated parison in a molten state.

1: Double container 2: Container body 3: Outer shell 3a: Open end 3b: Annular convex portion 3c: Through hole 3f: Recessed portion 3g: Projection 3h: Projection 3i: Projection 4: Inner bag 4c: Projecting portion 4c1: Projecting cylinder 4c2: Engaging projection 4c3: Engaging flange 4c4: Contact flange 4c5: Circumferential inclined surface 4e : Protrusion 4f : Convex part 5 : Mouth part 5a : Engagement part 5a1 : Male thread part 5b : Flange 5c : Open end 6 : Body part 6b : Shoulder part 6c : Body part main body 6d : Curved part 6d1 : Part 6e : Reduced diameter part 7 : Bottom part 7a : Bottom concave area 7a1 : Peripheral surface 7a2 : Bottom surface 7b : Peripheral area 8 : Mouth attachment member 8a : Outer cylinder 8c : Inner cylinder 8d : Engagement part 8d1 : Female thread portion 8e : Claw portion 8e1 : Upper surface 8f : Top plate 8g : Discharge port 8h : Through hole 8i : Protrusion 9 : Concave and recessed shape 9a : Concave streak 9b : Convex streak 13 : Outer preform 13a : Mouth portion 13b : Body portion 13c : Bottom portion 13d : Annular convex portion 13f : Concave portion 13h : Protrusion 13i : Protrusion 14 : Inner preform 14a : Mouth portion 14b : Body portion 14c : Bottom portion 14c1 : Positioning pin 14d : Protrusion 14f : Convex portion 15 : Preform 15a : Mouth portion 15b : Body portion 15c : Bottom portion 19 : Concave and recessed shape 24 : Anti-loosening structure

Claims (7)

A double container comprising a container body having an inner bag and an outer shell,
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 body portion includes a curved portion that curves so as to bulge outward,
When the diameter of the container body at the portion where the radius of curvature of the curved portion is smallest is D and the radius of curvature is R,
R/D is 0.5 or more,
The mouth portion is provided with a flange,
the body extends from the flange to the bottom;
The radius of curvature of the body portion is smallest at the curved portion,
the body portion includes a tapered portion that is located closer to the bottom portion than the curved portion and that taperes toward the bottom portion,
The double container has a body portion, the entire body portion from the curved portion to the bottom portion being the reduced diameter portion . A double container as described in claim 1 (excluding those in which the opening is provided with an outside air introduction hole that penetrates the outer shell and connects between the outer shell and the inner bag). The double container according to claim 1 or claim 2 ,
The double container is configured so that the inner bag can be pulled out from the outer shell. The double container according to any one of claims 1 to 3,
The double container is configured so that the inner bag can be twisted to reduce its diameter and then pulled out from the outer shell. The double container according to any one of claims 1 to 4 ,
Further provided with a mouth attachment member,
the mouth-attaching member is configured to be attachable to the mouth, and the inner bag is configured to rotate in accordance with the rotation of the mouth-attaching member;
The double container is configured so that the inner bag is twisted as the opening attachment member is rotated, thereby reducing the diameter of the body. The double container according to any one of claims 1 to 5 ,
The body portion has a shoulder portion whose outer diameter increases with increasing distance from the mouth portion,
the shoulder portion has an inclination angle of 25 degrees or less with respect to the central axis of the mouth portion;
If the inner diameter of the mouth of the outer shell is D2,
D/D2 is 1.8 or less,
If the diameter of the bottom surface of the recess provided in the bottom portion is D3 and the inner diameter of the mouth portion of the outer shell is D2,
A double container in which D3/D2 is 0.6 or less . A method for manufacturing a double container according to any one of claims 1 to 6 ,
The double container is configured so that the inner bag can be pulled out from the outer shell,
A biaxially stretched blow molding process is provided.
In the biaxially stretched blow molding step, a preform formed by covering an outer preform on an inner preform is heated and biaxially stretched blow molded to form the container body.