Preform for double container molding

Abstract

To make it easy to peel an outer peripheral surface of an inner container from an inner peripheral surface of an outer container as contents decrease, even without providing a release agent layer.SOLUTION: A preform for double container molding includes an inner preform 11 for molding an inner container X1, and an outer preform 12 for molding an outer container X2. With a mouth 21 of the inner preform fitted into a mouth 22 of the outer preform, the inner preform is inserted into the outer preform, and a vertical groove 16 extending downward from an upper opening edge 15 of the outer preform is formed on an inner surface of the mouth of the outer preform, with an outside air inlet hole 13 opening in the vertical groove, and a flange part 25 extending continuously over an entire circumferential length of the mouth of the inner preform and abutting against the upper opening edge of the outer preform to close the upper opening of the vertical groove, the outside air inlet hole being spaced downward from the upper opening edge of the outer preform, and the inner surface of the mouth of the outer preform and an outer surface of the mouth of the inner preform abut against each other over an entire area except for the vertical groove.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a preform for forming a double container.

Background Art

[0002] A preform for forming a double container including an inner container that is reduced in volume and deformed as the content to be contained decreases, and an outer container in which the inner container is installed and an outside air introduction hole for introducing outside air between the inner container and the outer container as the content decreases is provided with a bottomed cylindrical inner preform for forming the inner container and a bottomed cylindrical outer preform for forming the outer container. As this type of preform for forming a double container, for example, as shown in Patent Document 1 below, a configuration in which an inner preform is fitted inside an outer preform and a release agent layer is provided between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform is known. In the double container formed with this preform, when outside air is introduced between the inner container and the outer container through the outside air introduction hole as the content decreases, the outer peripheral surface of the inner container can be easily peeled off from the inner peripheral surface of the outer container.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional preform for forming a double container, since a release agent layer is provided between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform, there is a problem that the manufacturing is difficult.

[0005] The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a preform for double container molding that can easily peel the outer peripheral surface of the inner container from the inner peripheral surface of the outer container as the content decreases, even without providing a release agent layer.

Means for Solving the Problems

[0006] The present invention employs the following means to solve the above problems. That is, the preform for double container molding of the present invention includes an inner container that undergoes volume reduction deformation as the content to be contained decreases, and an outer container that houses the inner container and has an outside air introduction hole formed between the outer container and the inner container to introduce outside air as the content decreases, and is a preform for molding a double container including a bottomed cylindrical inner preform for molding the inner container and a bottomed cylindrical outer preform for molding the outer container. The inner preform is inserted into the outer preform with the mouth portion of the inner preform fitted into the mouth portion of the outer preform. A vertical groove extending downward from the upper end opening edge of the outer preform is formed on the inner peripheral surface of the mouth portion of the outer preform, and the outside air introduction hole opens into the vertical groove. A flange portion is provided at the mouth portion of the inner preform that continuously extends over the entire circumferential length and abuts against the upper end opening edge of the outer preform to close the upper end opening of the vertical groove. The outside air introduction hole is separated downward from the upper end opening edge of the outer preform, and the inner peripheral surface of the mouth portion of the outer preform and the outer peripheral surface of the mouth portion of the inner preform are in contact with each other over the entire area excluding the vertical groove.

[0007] In the present invention, a vertical groove extending downward from the upper end opening edge of the outer preform is formed on the inner peripheral surface of the mouth portion of the outer preform, and the outside air introduction hole opens into the vertical groove. Therefore, even when the mouth portion of the inner preform is fitted into the mouth portion of the outer preform and the relative movement of the outer preform and the inner preform is suppressed, when outside air is introduced between the inner container and the outer container through the outside air introduction hole, it will pass through the vertical groove, and it is possible to easily peel the outer peripheral surface of the inner container from the inner peripheral surface of the outer container as the content decreases, even without providing a release agent layer. Since the vertical groove extends downward from the upper end opening edge of the outer preform, the vertical groove can be easily provided on the inner peripheral surface of the outer preform without complicating the structure of the molding die. Since the inner preform is provided with a flange portion that continuously extends over the entire circumferential length at the mouth portion and abuts against the upper end opening edge of the outer preform, the relative movement between the outer preform and the inner preform can be reliably suppressed. Since the flange portion closes the upper end opening of the vertical groove, as the content decreases, the portion where outside air enters between the inner container and the outer container can be limited to the outside air introduction hole. Thereby, it becomes easier to maintain the momentum when the outside air enters between the inner container and the outer container, and it becomes possible to reliably peel the outer peripheral surface of the inner container from the inner peripheral surface of the outer container, and it becomes easier to make the reduced deformation shape of the inner container into the desired shape, and the remaining amount of the content can be suppressed.

[0008] The inner peripheral surface and the outer peripheral surface at the mouth portion of the inner preform may extend along the central axis line in a longitudinal sectional view along the central axis line of the inner preform.

[0009] In this case, since the inner peripheral surface and the outer peripheral surface at the mouth portion of the inner preform extend along the central axis line in a longitudinal sectional view along the central axis line of the inner preform, the relative movement between the outer preform and the inner preform can be reliably suppressed.

[0010] A ridge portion that protrudes radially outward, continuously extends over the entire circumferential length, and presses against the inner peripheral surface of the mouth portion of the outer preform may be provided on the outer peripheral surface at the mouth portion of the inner preform.

[0011] In this case, since a ridge portion that presses against the inner peripheral surface of the mouth portion of the outer preform is provided on the outer peripheral surface at the mouth portion of the inner preform, the relative movement between the outer preform and the inner preform can be reliably suppressed.

[0012] A diffusion gap that continuously extends over the entire circumferential length may be provided between the connection portion between the lower surface of the flange portion on the outer peripheral surface of the inner preform and the connection portion between the inner peripheral surface and the upper end opening edge of the outer preform.

[0013] In this case, since a diffusion gap is provided between the connection portion between the lower surface of the flange portion on the outer peripheral surface of the inner preform and the connection portion between the inner peripheral surface and the upper end opening edge of the outer preform, as the content decreases, the outside air introduced between the inner container and the outer container through the outside air introduction hole can be made to flow through the diffusion gap, making it easier to spread over the entire circumferential length at the mouth portion of the double container, and facilitating making the reduced deformation shape of the inner container into the intended shape.

Advantages of the Invention

[0014] According to this invention, even without providing a release agent layer, as the content decreases, the outer peripheral surface of the inner container can be easily peeled from the inner peripheral surface of the outer container.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0016] Hereinafter, with reference to the drawings, a preform for double container molding according to the first embodiment will be described. As shown in FIGS. 1 to 4, the preform 1 for forming a double container includes an inner container X1 that undergoes volume reduction deformation as the content to be contained decreases, and an outer container X2 that houses the inner container X1 and has an outside air introduction hole 13 formed between the inner container X1 and the outside air as the content decreases. The preform 1 is used to form a double container X. The double container X is formed by blow molding the preform 1 for forming a double container. In the double container X, the inner container X1 is highly flexible and is provided so as to be separable from the inner surface of the outer container X2.

[0017] The preform 1 for forming a double container includes a bottomed cylindrical inner preform 11 for forming the inner container X1 and a bottomed cylindrical outer preform 12 for forming the outer container X2. In FIG. 1, the inner preform 11 is hatched. As shown in FIG. 2, the mouth part (hereinafter referred to as the outer mouth part) 22 of the outer preform 12 has the mouth part (hereinafter referred to as the inner mouth part) 21 of the inner preform 11 inserted therein, and the bottom part (hereinafter referred to as the outer bottom part) 24 of the outer preform 12 has the bottom part (hereinafter referred to as the inner bottom part) 23 of the inner preform 11 inserted therein.

[0018] The inner preform 11 and the outer preform 12 are arranged coaxially with a common axis. Hereinafter, this common axis is referred to as the central axis O. The side of the inner mouth part 21 and the outer mouth part 22 along the central axis O is referred to as the upper side, and the side of the inner bottom part 23 and the outer bottom part 24 along the central axis O is referred to as the lower side. When viewed from the vertical direction, the direction intersecting the central axis O is referred to as the radial direction, and the direction of orbiting around the central axis O is referred to as the circumferential direction.

[0019] The materials of the inner preform 11 and the outer preform 12 are synthetic resin materials, and they may be of the same material or different materials from each other. Examples of synthetic resin materials include, for example, PET (polyethylene terephthalate), PP (polypropylene), PE (polyethylene), nylon (polyamide), and EVOH (ethylene-vinyl alcohol copolymer).

[0020] As shown in Fig. 4, the inner opening portion 21 is fitted inside the outer opening portion 22. The outer peripheral surface of the inner opening portion 21 is in contact with the inner peripheral surface of the outer opening portion 22 over the entire vertical length. As shown in Fig. 2, a gap is provided over the entire vertical length in a portion located below the inner opening portion 21 and the outer opening portion 22 between the outer peripheral surface of the inner preform 11 and the inner peripheral surface of the outer preform 12.

[0021] On the outer peripheral surface of the outer opening portion 22, a male screw portion 22a to which a cap (not shown) is screwed, a sealing projection portion 22b into which the peripheral wall portion of a cap (not shown) is externally fitted, and a neck ring 22c are formed in this order from above downward. Note that the cap may be undercut and fitted to the outer opening portion 22.

[0022] The sealing projection portion 22b and the neck ring 22c project radially outward from the outer opening portion 22 and continuously extend over the entire circumferential length. An airtight seal is provided between the outer peripheral surface of the sealing projection portion 22b and the inner peripheral surface of the peripheral wall portion of a cap (not shown). The outer diameter of the neck ring 22c is larger than the outer diameter of the sealing projection portion 22b. The neck ring 22c is located below the peripheral wall portion of a cap (not shown).

[0023] The above-described outside air introduction hole 13 is formed in the outer opening portion 22. The outside air introduction hole 13 is located above the sealing surface that is located most radially outward in the sealing projection portion 22b and continuously extends over the entire circumferential length. The vertical positions of the outside air introduction hole 13 and the lower portion of the male screw portion 22a are the same as each other. Here, the male screw portion 22a extends intermittently in the circumferential direction, and the outside air introduction hole 13 is provided in the intermittent portion in the circumferential direction of the male screw portion 22a. A vertical groove 16 extending downward from the upper end opening edge 15 of the outer preform 12 is formed in the inner peripheral surface of the outer opening portion 22. The outside air introduction hole 13 opens into the vertical groove 16. The lower end portion of the vertical groove 16 is located below the neck ring 22c.

[0024] As shown in FIG. 1, a plurality of outside air introduction holes 13 and vertical grooves 16 are provided at equal intervals in the circumferential direction. In the illustrated example, four vertical grooves 16 are provided at intervals of 90° around the central axis O as viewed from the vertical direction. One outside air introduction hole 13 opens into each of two vertical grooves 16 that face each other in the radial direction among the four vertical grooves 16. Note that the outside air introduction holes 13 may open into all of the vertical grooves 16, or a plurality of outside air introduction holes 13 may open into one vertical groove 16.

[0025] The inner mouth portion 21 is provided with a flange portion 25 that extends continuously over the entire circumferential length and abuts against the upper end opening edge 15 of the outer preform 12. As shown in FIG. 3, the flange portion 25 closes the upper end opening of the vertical groove 16.

[0026] As shown in FIG. 4, a ridge portion 26 that protrudes radially outward, extends continuously over the entire circumferential length, and presses against the inner circumferential surface of the outer mouth portion 22 is provided on the outer circumferential surface of the inner mouth portion 21. A plurality of ridge portions 26 are provided at intervals in the vertical direction. As shown in FIG. 3, the ridge portion 26 is located above the outside air introduction hole 13 of the outer mouth portion 22. Note that the ridge portion 26 may not be provided.

[0027] The inner circumferential surface and the outer circumferential surface of the inner mouth portion 21 extend along the central axis O in a longitudinal sectional view along the central axis O. At least the inner circumferential surface of the inner circumferential surface and the outer circumferential surface of the inner mouth portion 21 extends parallel to the central axis O. In the illustrated example, the inner circumferential surface and the outer circumferential surface of the inner mouth portion 21 extend parallel to the central axis O. The “parallel” as used herein includes the draft from the molding die.

[0028] The inner mouth portion 21 is a portion of the inner preform 11 that includes the same position in the vertical direction as the lower surface of the necking 22c in the outer preform 12 and is located above it. In the preform 1 for double container molding, the portion that includes the same position in the vertical direction as the lower surface of the necking 22c and is located above it is a portion whose shape does not change before and after blow molding.

[0029] On the outer peripheral surface of the inner preform 11, a plurality of ribs 11a that project radially outward and are adjacent to the inner peripheral surface of the outer preform 12 are formed at intervals in the circumferential direction at a portion continuous with the lower end of the inner mouth portion 21. The ribs 11a maintain the vertical communication state between the outer peripheral surface of the inner container X1 and the inner peripheral surface of the outer container X2 in the double container X. Note that the rib 11a may be a portion whose shape does not change before and after blow molding, or may be a portion that contacts the inner peripheral surface of the outer container X2 formed by the outer preform 12 after blow molding.

[0030] A diffusion gap A that continuously extends over the entire circumferential length is provided between the connection portion of the outer peripheral surface of the inner preform 11 with the lower surface of the flange portion 25 and the connection portion of the inner peripheral surface of the outer preform 12 with the upper end opening edge 15. The diffusion gap A opens into the vertical groove 16. The connection portion of the outer peripheral surface of the inner preform 11 with the lower surface of the flange portion 25 is formed in a curved surface shape that is recessed radially inward. The connection portion of the inner peripheral surface of the outer preform 12 with the upper end opening edge 15 is formed in a curved surface shape that protrudes radially inward.

[0031] As described above, according to the preform 1 for forming a double container according to the present embodiment, a vertical groove 16 that extends downward from the upper end opening edge 15 of the outer preform 12 is formed on the inner peripheral surface of the outer mouth portion 22, and the outside air introduction hole 13 opens into the vertical groove 16. Therefore, even when the inner mouth portion 21 is fitted into the outer mouth portion 22 and the relative movement of the outer preform 12 and the inner preform 11 is suppressed, when outside air is introduced between the inner container X1 and the outer container X2 through the outside air introduction hole 13, it will pass through the vertical groove 16. Without providing a release agent layer, it is possible to easily peel the outer peripheral surface of the inner container X1 from the inner peripheral surface of the outer container X2 as the content decreases.

[0032] Since the vertical groove 16 extends downward from the upper end opening edge 15 of the outer preform 12, the vertical groove 16 can be easily provided on the inner peripheral surface of the outer preform 12 without complicating the structure of the molding die. Since the inner mouth portion 21 is provided with a flange portion 25 that continuously extends over the entire circumferential length and abuts against the upper end opening edge 15 of the outer preform 12, the relative movement between the outer preform 12 and the inner preform 11 can be reliably suppressed.

[0033] Since the flange portion 25 closes the upper end opening of the vertical groove 16, as the content decreases, the portion where outside air enters between the inner container X1 and the outer container X2 can be limited to the outside air introduction hole 13. As a result, it becomes easier to maintain the momentum when outside air enters between the inner container X1 and the outer container X2, and it becomes possible to reliably peel the outer peripheral surface of the inner container X1 from the inner peripheral surface of the outer container X2, and it also becomes easier to make the reduced deformation shape of the inner container X1 into the desired shape, and the remaining amount of the content can be suppressed.

[0034] Since the inner peripheral surface and the outer peripheral surface of the inner mouth portion 21 extend along the central axis O in a longitudinal cross-sectional view along the central axis O, the relative movement between the outer preform 12 and the inner preform 11 can be reliably suppressed.

[0035] Since a ridge portion 26 that presses against the inner peripheral surface of the outer mouth portion 22 is provided on the outer peripheral surface of the inner mouth portion 21, the relative movement between the outer preform 12 and the inner preform 11 can be reliably suppressed.

[0036] Since a diffusion gap A is provided between the connection portion of the outer peripheral surface of the inner preform 11 with the lower surface of the flange portion 25 and the connection portion of the inner peripheral surface and the upper end opening edge 15 of the outer preform 12, as the content decreases, the outside air introduced between the inner container X1 and the outer container X2 through the outside air introduction hole 13 can be made to flow through the diffusion gap A, so that it becomes easier to spread over the entire circumferential length at the mouth portion of the double container X, and it becomes easier to make the reduced deformation shape of the inner container X1 into the desired shape.

[0037] Next, the preform 2 for double container molding according to the second embodiment will be described with reference to FIGS. 5 and 6. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted, and only the differences will be described.

[0038] In this embodiment, the rib 11a is in contact with the inner peripheral surface of the outer preform 12. The vertical positions of the upper end portion of the rib 11a and the lower end portion of the vertical groove 16 are the same as each other. The lower end portion of the rib 11a is located below the vertical groove 16. In the preform 2 for double container molding, at the boundary between the portion whose shape does not change before and after blow molding and the portion that is stretched during blow molding, among the ribs 11a, the contact portion that is in contact with the inner peripheral surface of the outer preform 12 is located. In the preform 2 for double container molding, the inner mouth portion 21 and the portion having the same vertical position as the contact portion of the rib 11a may be regarded as the portion whose shape does not change before and after blow molding, and the portion located below the contact portion of the rib 11a may be regarded as the portion that is stretched during blow molding.

[0039] As described above, according to the preform 2 for double container molding according to this embodiment, similar to the preform 1 for double container molding, even without providing a release agent layer, as the content decreases, it is possible to easily peel the outer peripheral surface of the inner container X1 from the inner peripheral surface of the outer container X2, etc.

[0040] Note that the technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0041] It is not necessary to provide a diffusion gap A between the connection portion of the outer peripheral surface of the inner preform 11 with the lower surface of the flange portion 25 and the connection portion of the inner peripheral surface and the upper end opening edge 15 of the outer preform 12.

[0042] In addition, within the scope not departing from the gist of the present invention, it is possible to appropriately replace the components in the above-described embodiment with well-known components, and the above-described embodiment and the modification examples may be appropriately combined.

Explanation of Reference Numerals

[0043] 1, 2 Preforms for double container forming 11 Inner preform 12 Outer preform 13 Outer air introduction hole 15 Upper end opening edge 16 Vertical groove 21 Inner mouth part (mouth part of inner preform) 22 Outer mouth part (mouth part of outer preform) 25 Flange part 26 Ridge part A Diffusion gap O Central axis X Double container X1 Inner container X2 Outer container

Claims

1. An inner container that undergoes volume reduction deformation as the content to be contained decreases, A double container molding preform comprising: an outer container in which the inner container is housed, and an outside air introduction hole for introducing outside air between the inner container and the outer container is formed as the content decreases, The preform includes a bottomed cylindrical inner preform for forming the inner container and a bottomed cylindrical outer preform for forming the outer container, The inner preform is inserted into the outer preform with the mouth portion of the inner preform fitted into the mouth portion of the outer preform, A vertical groove extending downward from the upper end opening edge of the outer preform is formed on the inner peripheral surface of the mouth portion of the outer preform, The outside air introduction hole opens into the vertical groove, The mouth portion of the inner preform is provided with a flange portion that extends continuously over the entire circumferential length and abuts against the upper end opening edge of the outer preform to close the upper end opening of the vertical groove, The outside air introduction hole is spaced downward from the upper end opening edge of the outer preform, A preform for double container molding, wherein the inner peripheral surface of the mouth portion of the outer preform and the outer peripheral surface of the mouth portion of the inner preform are in contact with each other over the entire area excluding the vertical groove.

2. The preform for double container molding according to claim 1, wherein the inner peripheral surface and the outer peripheral surface of the mouth portion of the inner preform extend along the central axis in a longitudinal sectional view along the central axis of the inner preform.

3. The preform for double container molding according to claim 1 or 2, wherein a ridge portion that protrudes radially outward, extends continuously over the entire circumferential length, and is in pressure contact with the inner peripheral surface of the mouth portion of the outer preform is provided on the outer peripheral surface of the mouth portion of the inner preform.

4. Between the connection portion of the outer peripheral surface of the inner preform and the lower surface of the flange portion, And the connection portion of the inner peripheral surface and the upper end opening edge of the outer preform, A diffusion gap that extends continuously over the entire circumferential length is provided. The preform for double container molding according to any one of claims 1 to 3.

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