Double container and manufacturing method thereof

Abstract

To provide a double container capable of reducing the residual amount of a content in an inner container after volume reduction deformation, and to provide a manufacturing method thereof.SOLUTION: There is provided a double container having a bottomed cylindrical outer container 10 which has a bottom part 15 at the lower end of a barrel part 14 connected to the lower end of a mouth part 12 through a shoulder part 13 and has them integrally formed, and an inner container 20 which is peelably laminated on the inner surface 11 of the outer container 10 and is peeled from the inner surface 11 as a content decreases, thereby being volume-reduced and deformed, in which a bottom part 25 of the inner container 20 has a hemispherical shape, and an internal space S is disposed between the bottom part 25 of the inner container 20 and the barrel part 14 and the bottom part 15 of the outer container 10 opposed to the bottom part 25.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a double container having an inner container capable of shrinking and deforming inside an outer container, and a method for manufacturing the same. [Background technology]

[0002] 2. Description of the Related Art Double-layered containers (delaminated containers) are known which are configured by disposing a bag-shaped inner container that is peelably laminated on the inner surface of an outer container and that is shrinkable (reducible) (see, for example, Patent Document 1). Such double containers are sometimes used, for example, as pump-equipped containers for toiletry products such as shampoo, with a nozzle head that can be raised and lowered at the opening and a pump mechanism equipped with a cylinder and pipes that draw up the contents as the nozzle head rises and falls.

[0003] In such a pump-equipped container, when the nozzle head is pressed down to operate the pump, the contents in the inner container are drawn up from the lower end of the pipe, and at the same time the inner container is put under negative pressure, causing it to shrink and deform, making it possible to effectively dispense the contents. Also, by forming an air hole in the outer container, it is possible to eliminate the negative pressure between the inner and outer containers and prevent deformation of the outer container due to negative pressure.

[0004] The double container as described above can be formed by blow molding the inner preform for forming the inner container in a state where the inner preform is fitted into the outer container (for example, Patent Document 2). The bottom of the outer container constituting such a double container is configured with a crest portion (also called a "depression portion") that is protruded upward (toward the inside of the container) and a ground portion that is annularly arranged along the circumferential direction at its base portion, and the bottom of the inner container is layered on the crest portion and the ground portion in a state of tight contact with each other. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-26893 [Patent Document 2] Japanese Patent Application Publication No. 5-31790 Summary of the Invention [Problem to be solved by the invention]

[0006] In the volume reduction deformation in Patent Document 1, the body of the inner container is mainly separated from the body of the outer container with which it was in close contact and deflated, but the bottom of the inner container remains in close contact with the crest and ground of the outer container, so a residual space (see "Limit Space X" in Patent Document 1) is formed in the circumferential direction between the deflated body of the inner container and the bottom of the inner container as it is. After the volume reduction deformation, the contents are stored in this residual space, but since they are stored in a dispersed state in the residual space along the circumferential direction, even if the lower end of the pipe can be placed in this residual space, there is a limit to how much the contents can be sucked up, and there is a problem in that it is difficult to reduce the remaining amount of contents.

[0007] The present invention aims to solve the problems in the conventional technology described above by creating a double container and a manufacturing method thereof that can reduce the amount of contents remaining in the inner container after volume reduction and deformation. [Means for solving the problem]

[0008] Among the means for solving the above problems, the first means of the present invention is A cylindrical double container with a bottom is configured to include an outer container with a bottom that is integrally formed with a body portion that is connected to the lower end of a mouth portion via a shoulder portion, and an inner container that is peelably laminated on the inner surface of the outer container and peels off from the inner surface as the contents decrease, thereby reducing in volume and deforming, The bottom of the inner container is formed to have a hemispherical shape, and an internal space is provided between the bottom of the inner container and the body and bottom of the outer container facing it. In the first aspect of the present invention, since it is possible to concentrate the contents in the center of the bottom of the inner container whose volume has been reduced and deformed, it is possible to reduce the amount of contents remaining in the inner container.

[0009] A second aspect of the present invention is the above-mentioned first aspect, further comprising the step of forming an air hole in the bottom of the outer container, the air hole communicating with the internal space. With the above-mentioned means, it is possible to adjust the internal pressure in the internal space via the ventilation hole, and thus the inner container can be smoothly reduced in volume.

[0010] The third aspect of the present invention is the above-mentioned second aspect, further comprising the addition of a bottom ridge portion that protrudes in a convex arc shape in cross section toward the internal space at the bottom of the outer container, and a grounding portion formed in an annular shape at the base of the bottom ridge portion, and the air hole is formed at a position radially inward of the grounding portion of the bottom ridge portion. With the above-mentioned means, it is possible to prevent the ventilation holes from being blocked when the double container 1 is placed on a placement surface, and therefore it is possible to achieve smooth volume reduction deformation of the inner container.

[0011] A fourth aspect of the present invention is a method for producing a double container according to any one of the above aspects, an outer container molding step of setting the outer container preform in a predetermined mold and forming the outer container by blow molding; a step of drilling the vent hole in the bottom of the blow-molded outer container; an inner-container molding step of setting the outer container in a second mold, arranging an inner-container preform, which has been heated to a temperature at which it can be stretched, in the outer container, and blow-molding the preform to form the inner container; The perforation step is performed to set the total opening area of ​​the ventilation holes to 0.5 to 1.0 mm 2 The present invention is characterized in that it includes a process in which the range of In the fourth aspect of the present invention, during blow molding of the inner container, it is possible to prevent the local formation of thick-walled parts that hinder volume reduction deformation, and the local formation of thin-walled parts that are prone to tearing. A fifth aspect of the present invention is the above-mentioned aspect, further comprising the step of: the inner container molding step including a step of axially stretching the inner container preform by a stretch rod. In the fifth means, as in the fourth means, the molding state of the inner container can be made good. Effect of the Invention

[0012] In the present invention, the amount of content remaining in the inner container after the volume reduction deformation can be further reduced. In particular, when the contents are high-priced items such as luxury cosmetics, containers with smaller contents tend to be used; however, the smaller the container, the higher the ratio of the remaining amount to the initial filling amount, so this is effective in reducing the remaining amount of contents even further. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a cross-sectional view of a double container showing an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a double container showing an embodiment of the present invention. In the following, the direction along the container axis O will be referred to as the axial direction, the up-down direction or the height direction, the direction perpendicular to the container axis O will be referred to as the radial direction, and the direction circumferentially around the container axis O will be referred to as the circumferential direction. As shown in FIG. 1, the double container 1 of this embodiment is composed of an outer container 10 and an inner container 20 that is placed inside the outer container 10 and can be deformed to reduce in volume as the contents contained therein decrease, and the inner container 20 is stacked against the inner surface 11 of the outer container 10 in a manner that allows it to be peeled away from its tightly sealed state.

[0015] In this embodiment, the outer container 10 is made of polyethylene terephthalate (PET) and the inner container 20 is made of polypropylene (PP), but as long as the inner container 20 can be peeled off independently from the inner surface 11 of the outer container 10 and can be deformed to reduce its volume, the combination is not limited to this, and they may be made of the same material. Furthermore, each of the outer container 10 and the inner container 20 may have a single-layer structure or a laminated structure.

[0016] The outer container 10 is integrally formed into a cylindrical shape with a bottom, comprising a cylindrical mouth 12, a shoulder 13 formed at the lower end of the mouth 12 so as to expand in diameter downward, a body 14 formed in a tubular shape at the lower end of the shoulder 13, and a bottom 15 closing the lower end of the body 14. A male thread 12a is formed on the outer circumferential surface of the mouth 12 for screwing in a cap of a pump mechanism (not shown). The bottom 15 is formed with a bottom ridge 16 that rises upward (towards the internal space S described below) in a convex arc shape in cross section, and a ground contact portion 17 is disposed annularly along the circumferential direction at the base of the bottom ridge 16. The double container 1 is configured so that it can stand on its own when the ground contact portion 17 is placed on a mounting surface G such as a pedestal.

[0017] Furthermore, the bottom mountain portion 16 of the outer container 10 located radially inward from the ground contact portion 17 is perforated with an air vent 18 penetrating the bottom mountain portion 16 in the direction of the container axis O, and is configured so that air can pass between the inside and outside of the outer container 10 through this air vent 18. Since the air vent 18 functions as an outside air introduction hole, it is necessary to prevent the air vent 18 from being blocked when the double container 1 is placed on the placement surface G. For this reason, it is preferable to provide the air vent 18 in the bottom mountain portion 16 radially inward from the ground contact portion 17 as described above. The position of the vent hole 18 may be any position that communicates with the internal space S described below, and may be, for example, the boundary between the lower end of the body portion 14 and the bottom portion 15. Although this embodiment shows a configuration in which only one vent hole 18 is provided, a configuration having multiple vent holes 18 may also be used.

[0018] The inner container 20 is composed of an outer flange portion 21 formed so as to expand radially outward in a ring shape at the upper end of the mouth portion 12 of the outer container 10, a tubular portion 22 suspended from the inner end of the outer flange portion 21 and tightly fixed to the inner surface of the mouth portion 12, a shoulder portion 23 formed so as to expand radially downward at the lower end of the tubular portion 22 and releasably laminated against the inner surface 11 of the shoulder portion 13, a body portion 24 connected to the lower end of the shoulder portion 23 and releasably laminated against the inner surface 11 of the body portion 14, and a bottom portion 25 connected to the lower end of the body portion 24. The bottom 25 of the inner container 20 is formed by swelling outward in a semi-spherical shape from the lower end of the body 24 of the inner container 20, and an internal space S having a generally cone-shaped cross section is provided between the bottom 25 of the inner container 20 and the body 14 and crest 16 that face it. The deepest part 25a of the bottom 25 may or may not abut against the crest 16. The internal space S and the outside of the double container 1 are in communication with each other via the above-mentioned ventilation hole 18.

[0019] The double container 1 having the above-mentioned structure is used as a container with a pump by attaching a pump mechanism to the mouth 12 in the same manner as in the past (not shown). As an example, the pump mechanism is configured to have a nozzle head that is provided so as to be able to rise and fall relative to the mouth 12, and a cylinder and a pipe that pump up the contents as the nozzle head rises and falls. The cylinder and the pipe are arranged along the container axis O inside the inner container 20, and the lower end of the pipe is arranged in contact with or in close proximity to the deepest part 25a of the bottom 25. In such a container with a pump, when the nozzle head is pressed down to operate the pump, the content contained in the inner container 20 can be pumped up from the lower end of the pipe. Note that the pump mechanism is not limited to the one operated by pressing the nozzle head as described above, and pumps of various structures can be used, such as one operated by pulling a trigger lever.

[0020] When the pump is operated, the pressure inside the inner container 20 becomes negative, and the volume reduction deformation of the inner container 20 gradually progresses each time the pump is operated. In this embodiment, the volume reduction deformation occurs when the shoulder 23 of the inner container 20 peels off radially inward from the shoulder 13 of the outer container 10, and similarly the body 24 of the inner container 20 peels off radially inward from the body 14 of the outer container 10, and further the hemispherical bottom 25 shrinks and deforms radially inward and upward (toward the inside of the container) in the figure.

[0021] At this time, the lower end of a pipe (not shown) arranged in the double container 1 abuts against the deepest part 25a of the bottom 25 of the inner container 20 to restrict the shrinkage deformation upward in the figure (inward of the container), so that most of the inner container 20 shrinks and deforms almost uniformly toward the inside in the radial direction. Therefore, in the inner container 20 after the volume reduction deformation, the contents can be concentrated in one place, the deepest part 25a of the bottom 25 where the lower end of the pipe is arranged, and are not stored in a dispersed state as in the conventional case. Therefore, in the container with pipes, the contents stored in a concentrated state in the deepest part 25a of the inner container 20 after the volume reduction deformation can be efficiently pumped up and discharged through the pipe.

[0022] When the inner container 20 undergoes volume reduction and deformation, the internal pressure of the internal space S decreases accordingly, but since outside air flows into the internal space S through the air vents 18, it is possible to suppress this decrease in internal pressure of the internal space S. This makes it possible to suppress the occurrence of problems such as impeding the volume reduction and deformation of the inner container 20 or unexpected deformation of the outer container 10.

[0023] Here, a pump mechanism was attached to both the conventional double container and the double container according to this embodiment, and a comparative test was conducted on the remaining amount in the inner container 20 after the contents were discharged to the last drop. The average remaining amount in the conventional double container was 2.89% of the initial filling amount, whereas the average remaining amount in the double container 1 according to this embodiment was 0.16%. This confirmed that the double container 1 according to this embodiment can efficiently pump up and discharge the contents.

[0024] Next, a method for manufacturing the double container having the above structure will be described. The outer container preform is set in a first mold (not shown) and is blow molded to form the outer container 10 (outer container molding step). Furthermore, the vent holes 18 are drilled in the crest portion 16 of the bottom 15 of the blow-molded outer container 10 (drilling step). In this drilling step, the total opening area of ​​the vent holes 18 is set to 0.5 to 1.0 mm 2 The process includes steps within the range of: Incidentally, the method of drilling the ventilation holes 18 is not particularly limited, and for example, they may be formed almost simultaneously with the blow molding in the outer container molding process by using a convex drilling means that is movable forward and backward on the bottom of the mold, or they may be formed by using a punching means such as a punch in a subsequent process after the outer container molding process.

[0025] Next, the blow-molded outer container 10 is set in a second mold, an inner container preform heated to a temperature at which it can be stretched is placed in the outer container 10 (not shown), and the inner container preform is blow-molded (inner container molding step). This ensures that the center of the deepest part 25a of the hemispherical bottom 25 is positioned on the container axis O. Note that a stretching rod may or may not be used in the blow molding.

[0026] In the inner container molding process, the inner container preform expands with the inner surface 11 of the outer container 10 as a cavity. 2 ), the air in the internal space S between the outer container 10 and the inner container 20 cannot be completely discharged to the outside, and the air remaining in the internal space S is compressed, appropriately inhibiting the expansion of the inner container 20. As a result, the inner container 20 does not expand over the entire bottom 15 of the outer container 10, and the bottom 25 of the inner container 20 can be formed into a rounded hemispherical shape. Furthermore, when using a stretching rod to stretch the inner container 20 in the axial direction, the inner container 20 may be stretched until the bottom of the inner container 20 abuts on the bottom of the outer container 10, or it may be stretched to the extent that any gap is provided between the bottom of the inner container 20 and the bottom of the outer container 10.

[0027] Table 1 shows the results when double-walled containers were molded while changing the conditions of the vent holes provided in the bottom. In Table 1, the symbols shown in "Molding of inner container" in "Results of molded product" indicate the molding results, with ◯ meaning that the inner container's internal volume is 85% or more of the internal volume of the outer container, △ meaning that the inner container's internal volume is less than 85% of the internal volume of the outer container, and × meaning that the inner container had a defect such as a hole and could not be molded. The outer container shown in Table 1 has an internal volume of 230 ml.

[0028] [Table 1]

[0029] From Table 1, the total opening area (cross-sectional area) of the ventilation holes 18 is such that when air is blown into the internal space S of the sealed outer container 10 and the internal pressure reaches 1 MPa, the flow rate of the air discharged from the ventilation holes (if there are multiple ventilation holes, the total amount of the air) 18 is 66 to 132 L / min (0.066 to 0.132 m 3 / min).

[0030] In addition, the flow rate of the exhaust air is 66 to 132 L / min (0.066 to 0.132 m 3 The reason why 66L / min (0.066m 3 / min) (when the opening area of ​​the ventilation hole 18 is small), the expansion speed of the inner container 20 will be slow and the degree of expansion will be insufficient, raising the concern that localized thick-walled portions will be formed, and since such thick-walled portions are unlikely to shrink, there is a possibility that the volume reduction deformation of the inner container 20 will be hindered. Also, 132L / min (0.132m 3 / min) (when the opening area of ​​the ventilation hole 18 is large), the expansion speed of the inner container 20 becomes too fast, which makes it easy for localized thin-walled portions to form, and these thin-walled portions may then tear.

[0031] Although the configuration and the effects of the present invention have been described above based on the embodiments, the present invention is not limited to the above embodiments.

[0032] For example, in the above embodiment, the outer container 10 is cylindrical, but the outer container 10 may be polygonal cylindrical.

[0033] In the above embodiment, as an example of the use of the double container 1, a pump-equipped container in which a pump mechanism is attached to the mouth portion 12 and the contents are pumped up in response to the rise and fall of the nozzle head is shown and explained. However, the embodiment of the present invention is not limited to the above embodiment, and the double container 1 may be used in a squeeze container or the like that does not use a pump mechanism. [Industrial Applicability]

[0034] The present invention can expand the range of applications in the field of double containers in which the inner container undergoes volume reduction and deformation. [Explanation of symbols]

[0035] 1:Double container 10: Outer container 12: Mouth 12a: Male thread 13:Shoulder 14: Torso 15: Bottom 16: Bottom mountain part 17: Grounding part 18: Ventilation hole 20: Inner container 21: Outer flange 22:Cylinder part 23:Shoulder 24: Torso 25: Bottom 25a: The Deepest Part G: Placement surface O: Container axis S:Internal space

Claims

1. A cylindrical double container with a bottom is configured to include a cylindrical outer container (10) with a bottom (15) formed integrally with a body (14) connected to the lower end of a mouth (12) via a shoulder (13), and an inner container (20) that is peelably laminated on an inner surface (11) of the outer container (10) and peels off from the inner surface (11) as the contents decrease, thereby reducing in volume, The bottom (25) of the inner container (20) is formed to have a semispherical shape, A double container characterized in that an internal space (S) is provided between a bottom (25) of the inner container (20) and a body (14) and a bottom (15) of the outer container (10) facing the bottom (25) of the inner container.

2. 2. The double container according to claim 1, wherein a vent hole (18) communicating with the internal space (S) is formed through the bottom (15) of the outer container (10).

3. 3. The double container according to claim 2, wherein a bottom portion (15) of the outer container (10) is provided with a bottom ridge portion (16) that protrudes in a convex arc shape in cross section toward the internal space (S), and a ground portion (17) formed in an annular shape at the base of the bottom ridge portion (16), and the air vent (18) is formed at a position radially inward of the ground portion (17) of the bottom ridge portion (16).

4. A method for producing a double container according to any one of claims 1 to 3, comprising the steps of: an outer container molding step of forming the outer container (10) by setting the outer container preform in a predetermined mold and blow molding it; a step of drilling the vent hole (18) in the bottom (15) of the blow-molded outer container (10); an inner container molding step of setting the outer container (10) in a second mold, arranging an inner container preform heated to a stretchable temperature in the outer container (10), and blow molding the inner container (20); The boring step is to set the total opening area of ​​the vent holes (18) to 0.5 to 1.0 mm ２ A method for manufacturing a double container, comprising the steps of:

5. 5. The method for manufacturing a double container according to claim 4, wherein the inner container molding step includes a step of stretching the inner container preform in the axial direction by a stretching rod.

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