Preform for double-walled container molding

Abstract

To make it easy for an outer circumferential surface of an inner container to separate from an inner circumferential surface of an outer container as the content reduces even when no separating material layer is provided.SOLUTION: A preform for molding a double container comprises: an inner preform 11 with a bottomed cylindrical shape for molding an inner container X1; and an outer preform 12 with a bottomed cylindrical shape for molding an outer container X2. The inner preform is inserted into the outer preform in a state in which a mouth portion 21 of the inner preform is fitted in a mouth portion 22 of the outer preform. A vertical groove 16 extended downward from an opening edge 15 of an upper end of the outer preform is formed on an inner circumferentia surface of the mouth portion of the outer preform. An outer air introduction hole 13 opens to the vertical groove. A flange portion 25 that is continuously extended over the whole length in a circumferential direction, and comes into contact with an upper end opening edge of the outer preform to plug an upper end opening of the vertical groove, is provided on the mouth portion of the inner preform.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 contained content decreases, and an outer container that houses the inner container and has an outside air introduction hole formed between the inner container and the outside air as the contained 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. As this type of preform for forming a double container, for example, as shown in Patent Document 1 below, a configuration is known 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. In the double container formed by this preform, when outside air is introduced between the inner container and the outer container through the outside air introduction hole as the contained 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 circumstances described above, and aims to provide a preform for forming double-walled containers that makes it easier to separate the outer surface of the inner container from the inner surface of the outer container as the contents decrease, even without providing a release agent layer. [Means for solving the problem]

[0006] To solve the above problems, the present invention employs the following means. Specifically, the present invention provides a preform for forming a double-walled container, which comprises an inner container that deforms in volume as the contents it contains decrease, and an outer container in which the inner container is housed, and which has an air intake hole formed between it and the inner container to introduce outside air as the contents decrease, the preform comprising a bottomed cylindrical inner preform for forming the inner container and a bottomed cylindrical outer preform for forming the outer container, wherein the inner preform is inserted into the outer preform with the mouth of the inner preform fitted into the mouth of the outer preform, a vertical groove is formed on the inner circumferential surface of the mouth of the outer preform extending downward from the upper end opening edge of the outer preform, the air intake hole is opened in the vertical groove, and the mouth of the inner preform is provided with a flange portion that extends continuously along the entire length in the circumferential direction and abuts against the upper end opening edge of the outer preform, closing the upper end opening of the vertical groove. The outside air intake hole is located below the upper opening edge of the outer preform. .

[0007] In this invention, a vertical groove is formed on the inner circumferential surface of the mouth of the outer preform, extending downward from the upper opening edge of the outer preform, and an outside air introduction hole is opened in the vertical groove. Therefore, even when the mouth of the inner preform is fitted into the mouth of the outer preform and relative movement between the outer and inner preforms is suppressed, when outside air is introduced between the inner container and the outer container through the outside air introduction hole, it passes through the vertical groove. This makes it easier to separate the outer circumferential surface of the inner container from the inner circumferential surface of the outer container as the contents decrease, even without providing a release agent layer. Since the longitudinal grooves extend downward from the upper opening edge of the outer preform, the longitudinal grooves can be easily provided on the inner circumferential surface of the outer preform without complicating the structure of the molding die. Since the inner preform is provided with a flange portion that extends continuously along its entire circumferential length and abuts against the upper opening edge of the outer preform, relative movement between the outer and inner preforms can be reliably suppressed. Since the flange portion closes the upper end opening of the vertical groove, as the contents decrease, the portion in which outside air enters between the inner container and the outer container can be limited to the outside air intake hole. This makes it easier to maintain the momentum of the outside air when it enters between the inner and outer containers, making it easier to reliably separate the outer surface of the inner container from the inner surface of the outer container, and also makes it easier to reduce the size of the inner container as intended, thereby minimizing the amount of remaining contents.

[0008] The inner and outer surfaces of the opening of the inner preform may extend along the central axis in a longitudinal cross-sectional view along the central axis of the inner preform.

[0009] In this case, the inner and outer surfaces of the opening of the inner preform extend along the central axis in a longitudinal cross-sectional view along the central axis of the inner preform, thus reliably preventing relative movement between the outer and inner preforms.

[0010] The outer circumferential surface of the opening of the inner preform may be provided with a projection that extends radially outward, continuously along the entire length in the circumferential direction, and presses against the inner circumferential surface of the opening of the outer preform.

[0011] In this case, since the outer circumferential surface of the opening of the inner preform is provided with a ridge that presses against the inner circumferential surface of the opening of the outer preform, relative movement between the outer and inner preforms can be reliably suppressed.

[0012] A diffusion gap extending continuously along the entire length in the circumferential direction may be provided between the connection portion between the outer peripheral surface of the inner preform and the lower surface of the flange portion, and the connection portion between the inner peripheral surface of the outer preform and the upper end opening edge.

[0013] In this case, a diffusion gap is provided between the connection point between the lower surface of the flange on the outer circumferential surface of the inner preform and the connection point between the inner circumferential surface and the upper opening edge of the outer preform. As the contents decrease, the outside air introduced between the inner container and the outer container through the outside air intake hole can be circulated through the diffusion gap, making it easier to distribute the outside air over the entire circumferential length of the mouth of the double container, and making it easier to achieve the desired shape when the inner container shrinks and deforms. [Effects of the Invention]

[0014] According to this invention, even without providing a release agent layer, the outer surface of the inner container can be easily separated from the inner surface of the outer container as the contents decrease. [Brief explanation of the drawing]

[0015] [Figure 1] This is a top view of a preform for double-walled container molding, as shown in one embodiment. [Figure 2] Figure 1 is a semi-longitudinal cross-sectional view including the section taken along arrow II according to the first embodiment. [Figure 3] This is a cross-sectional view taken along arrow III according to the first embodiment in Figure 1. [Figure 4] This is a cross-sectional view taken along arrow IV according to the first embodiment in Figure 1. [Figure 5] This is a cross-sectional view taken along arrow III according to the second embodiment of Figure 1. [Figure 6] This is a cross-sectional view taken along arrow IV according to the second embodiment of Figure 1. [Modes for carrying out the invention]

[0016] The preform for molding a double-walled container according to the first embodiment will be described below with reference to the drawings. 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 it holds decreases, and an outer container X2 that houses the inner container X1 and has an outside air introduction hole 13 formed between it and the inner container X1 to introduce 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 side of the outer mouth part 22 along the central axis O are referred to as the upper side, and the side of the inner bottom part 23 and the side of the outer bottom part 24 along the central axis O are 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), etc.

[0020] As shown in Figure 4, the inner opening 21 is fitted inside the outer opening 22. The outer circumferential surface of the inner opening 21 abuts against the inner circumferential surface of the outer opening 22 along its entire length in the vertical direction. As shown in Figure 2, a gap is provided between the outer circumferential surface of the inner preform 11 and the inner circumferential surface of the outer preform 12, in the portion located below the inner opening 21 and the outer opening 22, along the entire length in the vertical direction.

[0021] On the outer circumferential surface of the outer opening 22, a male threaded portion 22a to which a cap (not shown) is screwed, a sealing projection 22b to which the peripheral wall portion of the cap (not shown) is fitted, and a neck ring 22c are formed in this order from top to bottom. The cap may also be fitted onto the outer opening 22 with an undercut.

[0022] The sealed projection 22b and the neck ring 22c project radially outward from the outer opening 22 and extend continuously along the entire length of the circumferential direction. The outer surface of the sealed projection 22b and the inner surface of the circumferential wall of the cap (not shown) are airtightly sealed. The outer diameter of the neck ring 22c is larger than the outer diameter of the sealed projection 22b. The neck ring 22c is located below the circumferential wall of the cap (not shown).

[0023] The aforementioned outside air intake hole 13 is formed in the outer opening portion 22. The outside air intake hole 13 is located radially on the outermost side of the sealed projection 22b and is positioned above the sealing surface that extends continuously along its entire circumferential length. The vertical positions of the outside air intake hole 13 and the lower part of the male threaded portion 22a are the same. Here, the male threaded portion 22a extends intermittently in the circumferential direction, and the outside air intake hole 13 is provided in the intermittent circumferential portion of this male threaded portion 22a. A vertical groove 16 is formed on the inner circumferential surface of the outer opening portion 22, extending downward from the upper end opening edge 15 of the outer preform 12. An air intake hole 13 is opened in the vertical groove 16. The lower end of the vertical groove 16 is located below the neck ring 22c.

[0024] As shown in Figure 1, multiple air intake 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 90° intervals around the central axis O when viewed from above and below. Of the four vertical grooves 16, one air intake hole 13 is opened in each of the two vertical grooves 16 that are radially opposite to each other. Note that air intake holes 13 may be opened in all of the vertical grooves 16, or multiple air intake holes 13 may be opened in a single vertical groove 16.

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

[0026] As shown in Figure 4, the outer circumferential surface of the inner opening 21 is provided with a projection 26 that protrudes radially outward, extends continuously along its entire circumferential length, and is pressed against the inner circumferential surface of the outer opening 22. Multiple projections 26 are provided at intervals in the vertical direction. As shown in Figure 3, the projections 26 are located above the outside air intake hole 13 of the outer opening 22. Note that the projections 26 are not required.

[0027] The inner and outer surfaces of the inner opening 21 extend along the central axis O in a longitudinal cross-sectional view along the central axis O. Of the inner and outer surfaces of the inner opening 21, at least the inner surface extends parallel to the central axis O. In the illustrated example, the inner and outer surfaces of the inner opening 21 extend parallel to the central axis O. Here, "parallel" includes the draft angle from the molding die.

[0028] The inner opening portion 21 is the part of the inner preform 11 that includes the same position in the vertical direction relative to the lower surface of the neck ring 22c of the outer preform 12, and is located above it. In the double-walled container molding preform 1, the part that includes the same position in the vertical direction relative to the lower surface of the neck ring 22c, and is located above it, is the part whose shape does not change before and after blow molding.

[0029] On the outer circumferential surface of the inner preform 11, multiple ribs 11a are formed at circumferential intervals in the portion connected to the lower end of the inner opening 21, projecting radially outward and close to the inner circumferential surface of the outer preform 12. The ribs 11a maintain vertical communication between the outer circumferential surface of the inner container X1 and the inner circumferential surface of the outer container X2 in the double-walled container X. The rib 11a may be a part whose shape does not change before and after blow molding, or it may be a part that abuts against the inner circumferential surface of the outer container X2 formed by the outer preform 12 after blow molding.

[0030] A diffusion gap A is provided between the connection portion between the lower surface of the flange portion 25 on the outer circumferential surface of the inner preform 11 and the connection portion between the inner circumferential surface of the outer preform 12 and the upper end opening edge 15, extending continuously along the entire length in the circumferential direction. The diffusion gap A opens into the vertical groove 16. The connection portion between the inner preform 11's outer circumferential surface and the lower surface of the flange portion 25 is formed as a curved surface that is recessed radially inward. The connection portion between the outer preform 12's inner circumferential surface and the upper end opening edge 15 is formed as a curved surface that protrudes radially inward.

[0031] As described above, according to the double-walled container molding preform 1 of this embodiment, a vertical groove 16 is formed on the inner circumferential surface of the outer opening 22, extending downward from the upper opening edge 15 of the outer preform 12, and an outside air introduction hole 13 is opened in the vertical groove 16. Therefore, even when the inner opening 21 is fitted into the outer opening 22 and relative movement between 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 passes through the vertical groove 16. This makes it easier to separate the outer circumferential surface of the inner container X1 from the inner circumferential surface of the outer container X2 as the contents decrease, even without providing a release agent layer.

[0032] Since the vertical grooves 16 extend downward from the upper opening edge 15 of the outer preform 12, the vertical grooves 16 can be easily provided on the inner circumferential surface of the outer preform 12 without complicating the structure of the molding die. Since the inner opening portion 21 is provided with a flange portion 25 that extends continuously along the entire length in the circumferential direction and abuts against the upper end opening edge 15 of the outer preform 12, 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 contents decrease, the portion of outside air that enters between the inner container X1 and the outer container X2 can be limited to the outside air inlet hole 13. This makes it easier to maintain the momentum of the outside air when it enters between the inner container X1 and the outer container X2, making it easier to reliably separate the outer surface of the inner container X1 from the inner surface of the outer container X2, and also makes it easier to reduce the size of the inner container X1 as intended, thereby reducing the amount of remaining contents.

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

[0035] Since the outer circumferential surface of the inner opening 21 is provided with a protruding portion 26 that presses against the inner circumferential surface of the outer opening 22, 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 between the lower surface of the flange portion 25 on the outer peripheral surface of the inner preform 11 and the connection portion between the inner peripheral surface of the outer preform 12 and the upper end opening edge 15, as the contents decrease, the outside air introduced between the inner container X1 and the outer container X2 through the outside air introduction hole 13 can be circulated through the diffusion gap A, making it easier to distribute the outside air over the entire circumferential length of the mouth of the double container X, and making it easier to reduce the size of the inner container X1 to the desired shape.

[0037] Next, the double-walled container molding preform 2 according to the second embodiment will be described with reference to Figures 5 and 6. In the second embodiment, the same reference numerals are used for parts that are the same as those in the first embodiment, and their descriptions are omitted. Only the differences will be described.

[0038] In this embodiment, the rib 11a is in contact with the inner circumferential surface of the outer preform 12. The upper end of the rib 11a and the lower end of the longitudinal groove 16 are at the same vertical position. The lower end of the rib 11a is located below the longitudinal groove 16. In the double-walled container molding preform 2, the boundary between the portion whose shape does not change before and after blow molding and the portion that is stretched during blow molding is located at the contact portion of the rib 11a that abuts against the inner circumferential surface of the outer preform 12. In addition, in the double-walled container molding preform 2, the portion of the inner opening 21 and the portion of the rib 11a that is in the same vertical position as the contact portion may be designated as a portion whose shape does not change before and after blow molding, while the portion of the rib 11a located below the contact portion may be designated as a portion that is stretched during blow molding.

[0039] As described above, the double-walled container molding preform 2 according to this embodiment, similar to the double-walled container molding preform 1, makes it possible to easily separate the outer surface of the inner container X1 from the inner surface of the outer container X2 as the contents decrease, even without providing a release agent layer.

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

[0041] A diffusion gap A does not need to be provided between the connection portion between the lower surface of the flange portion 25 on the outer circumferential surface of the inner preform 11 and the connection portion between the inner circumferential surface of the outer preform 12 and the upper end opening edge 15.

[0042] Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above embodiments and modifications may be combined as appropriate. [Explanation of Symbols]

[0043] 1, 2 Preforms for double-walled container molding 11 Internal preform 12 External preforms 13. Outside air intake vent 15 Upper opening edge 16 vertical grooves 21. Inner opening (opening of the inner preform) 22 Outer opening (opening of the outer preform) 25 Flange section 26 Projection part A Diffusion gap O center axis X double container X1 Inner container X2 outer container

Claims

1. The inner container deforms and decreases in volume as the contents it holds decrease, A preform for forming a double container comprising: an inner container in which the inner container is housed, and an outer container having an air intake hole formed between it and the inner container for introducing outside air as the contents decrease, It comprises a bottomed cylindrical inner preform for forming the inner container and a bottomed cylindrical outer preform for forming the outer container, With the opening of the inner preform fitted into the opening of the outer preform, the inner preform is inserted into the outer preform. A longitudinal groove is formed on the inner circumferential surface of the opening of the outer preform, extending downward from the upper opening edge of the outer preform. The aforementioned vertical groove has an opening for the outside air intake, The opening of the inner preform is provided with a flange portion that extends continuously along its entire circumferential length and abuts against the upper end opening edge of the outer preform, thereby closing the upper end opening of the vertical groove. The aforementioned air intake hole is located below the upper opening edge of the outer preform, in a double-walled container molding preform.

2. The inner and outer surfaces of the inner preform at the mouth of the inner preform extend along the central axis in a longitudinal cross-sectional view along the central axis of the inner preform, as described in claim 1.

3. The double-walled container molding preform according to claim 1 or 2, wherein the outer circumferential surface of the mouth of the inner preform is provided with a ridge that protrudes radially outward, extends continuously along the entire length in the circumferential direction, and presses against the inner circumferential surface of the mouth of the outer preform.

4. The connection portion between the outer circumferential surface of the inner preform and the lower surface of the flange portion, The connection portion between the inner circumferential surface and the upper opening edge of the outer preform, A preform for double-walled container molding according to any one of claims 1 to 3, wherein a diffusion gap is provided between them, extending continuously along the entire length in the circumferential direction.

Images