Laminated preform, and method of producing double container

Abstract

To provide a laminated preform enabling formation of a double container that can easily separate the inner body from the outer body, and to also provide a method for producing a double container.SOLUTION: A laminated preform 1 includes: an outer preform 2 that has a bottom and a cylindrical shape with an inner circumferential surface having a threaded part 2j consisting of a female thread; and an inner preform 3 that has a bottom and a cylindrical shape with an outer circumferential surface having a flange 3d and a threaded part 3h consisting of a male thread. By threadably engaging the male thread with the female thread until the flange 3d contacts the opening end 2b of the outer preform 2 and the upper surface of the male thread contacts the lower surface of the female thread, the inner preform 3 is assembled into the outer preform 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminated preform and a method for manufacturing a double container.

Background Art

[0002] A double container having a bottomed cylindrical outer layer body and a bottomed cylindrical inner layer body, with the inner layer body laminated inside the outer layer body so as to be peelable from the outer layer body, is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For a double container as described above, from the viewpoint of recyclability and the like, it is desirable that the inner layer body can be easily separated from the outer layer body.

[0005] Therefore, an object of the present invention is to provide a laminated preform and a method for manufacturing a double container that can form a double container in which the inner layer body can be easily separated from the outer layer body.

Means for Solving the Problems

[0006] The laminated preform of the present invention has a bottomed cylindrical outer preform having a threaded portion to be screwed formed by a female threaded portion on its inner peripheral surface, and a bottomed cylindrical inner preform having a flange and a threaded portion formed by a male threaded portion on its outer peripheral surface. The male threaded portion is screwed into the female threaded portion so as to be detachable until the flange abuts against the open end of the outer preform and the upper surface of the male threaded portion abuts against the lower surface of the female threaded portion, whereby the inner preform is assembled inside the outer preform. It is a laminated preform.

[0007] In the laminated preform of the present invention, in the above configuration, the inner preform has an inner mouth portion body, and the inner mouth portion body has an upper region where the outer diameter and the inner diameter are constant in the vertical direction, and a lower region that tapers downward from the lower end of the upper region. The outer peripheral surface of the inner mouth portion body has the screwed portion only in the upper region, and at least the upper end portion of the lower region of the inner mouth portion body is a non-stretched portion that is not substantially stretched during biaxial stretch blow molding. It is preferably a laminated preform.

[0008] In the laminated preform of the present invention, in the above configuration, it is preferable that the inner preform has a cap engaging portion that can engage with the cap so as to be rotatable with the cap in the screwing-off direction with respect to the outer preform.

[0009] In the laminated preform of the present invention, in the above configuration, it is preferable that the inner preform is formed of polypropylene and the outer preform is formed of polyethylene terephthalate.

[0010] A method for manufacturing a double container of the present invention includes a laminated preform forming step of assembling a bottomed cylindrical inner preform having a screwed portion including a flange and a male screw portion on its outer peripheral surface inside a bottomed cylindrical outer preform having a female screw portion as a screwed portion on its inner peripheral surface until the flange abuts against the open end of the outer preform and the upper surface of the male screw portion abuts against the lower surface of the female screw portion by screwing the male screw portion into the female screw portion so as to be detachable, and a blow molding step of biaxially stretch blow molding the laminated preform. It is a method for manufacturing a double container.

[0011] The manufacturing method of the double container of the present invention, in the above configuration, the inner preform has an inner mouth part main body, the inner mouth part main body has an upper region where the outer diameter and the inner diameter are constant in the vertical direction, and a lower region that tapers downward from the lower end of the upper region, the outer peripheral surface of the inner mouth part main body has the screwing part only in the upper region, and at least the upper end part of the lower region of the inner mouth part main body is a non-stretched part that is not substantially stretched during biaxial stretch blow molding. It is preferable that it is a manufacturing method of a double container.

Effects of the Invention

[0012] According to the present invention, it is possible to provide a laminated preform and a manufacturing method of a double container capable of forming a double container in which the inner layer body can be easily separated from the outer layer body.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be illustrated and described with reference to the drawings.

[0015] As shown in FIG. 1, in one embodiment of the present invention, the laminated preform 1 has a bottomed cylindrical outer preform 2 centered on the central axis O, and a bottomed cylindrical inner preform 3 coaxially assembled inside the outer preform 2. By subjecting the laminated preform 1 to biaxial stretch blow molding, a double container 6 can be formed, having, for example, a bottomed cylindrical outer layer body 4 centered on the central axis O, and a bottomed cylindrical inner layer body 5 laminated inside the outer layer body 4 so as to be separable from the outer layer body 4, as shown in FIG. 2. Then, by attaching a cap 7 to the double container 6, a discharge container 8 can be formed, for example, as shown in FIG. 3.

[0016] In addition, in the present application, the term "separation" includes not only the case where the inner layer body 5 and the outer layer body 4 are separated from an adhesive state or a pseudo-adhesive state with almost no adhesive force, but also the case where the inner layer body 5 and the outer layer body 4 are separated from a close contact state with no adhesive force.

[0017] For convenience of explanation, the direction along the central axis O is also referred to as the vertical direction, the direction from the closed end 2a to the open end 2b of the outer preform 2 along the central axis O is also referred to as the upward direction, the opposite direction is also referred to as the downward direction, the direction along a straight line orthogonal to the central axis O is also referred to as the radial direction, and the direction around the central axis O is also referred to as the circumferential direction.

[0018] The outer preform 2 has a cylindrical outer mouth portion 2c centered on the central axis O, and a bottomed cylindrical outer body portion 2d extending downward from the lower end of the outer mouth portion 2c. Note that the appearance of the outer mouth portion 2c may be configured to have a cylindrical shape other than a cylindrical shape, such as a regular polygonal shape.

[0019] The outer mouth portion 2c is not substantially stretched during biaxial stretch blow molding and has the same shape as the outer layer mouth portion 4a of the outer layer body 4. The opening end face 2e (upper end face) of the outer mouth portion 2c has a sealing protrusion 2f that protrudes upward and forms an annular shape centered on the central axis O. The outer mouth portion 2c has an upper portion 2g with a constant outer diameter and inner diameter extending downward from the opening end 2b, a lower portion 2h with an outer diameter and inner diameter smaller than those of the upper portion 2g, and a neck ring 2i that protrudes radially outward at the boundary between the upper portion 2g and the lower portion 2h and forms an annular shape centered on the central axis O. Further, the inner peripheral surface of the outer mouth portion 2c has a threaded portion 2j that is a female thread centered on the central axis O only in the upper portion 2g.

[0020] Note that the threaded portion 2j may be provided so as to straddle from the upper portion 2g to the lower portion 2h, or the threaded portion 2j may be provided only in the lower portion 2h. The lower portion 2h may be configured to be equivalent to the upper portion 2g in terms of only the inner diameter or both the inner diameter and the outer diameter. The neck ring 2i may not be provided.

[0021] The outer barrel portion 2d is stretched in two axial directions, the vertical direction (axial direction) and the radial direction, during biaxial stretch blow molding and is formed into the outer layer barrel portion 4b of the outer layer body 4. The outer barrel portion 2d has an outer barrel body 2k that extends while reducing the diameter downward from the lower end of the outer mouth portion 2c, and a closing end 2a that protrudes downward and has a convex shape to close the lower end of the outer barrel body 2k. The outer layer barrel portion 4b has a bottomed cylindrical shape extending downward from the lower end of the outer layer mouth portion 4a. More specifically, it has a shoulder region 4c that widens downward from the lower end of the outer layer mouth portion 4a, a bottom region 4d including a grounding portion, and a barrel body region 4e connecting the shoulder region 4c and the bottom region 4d.

[0022] The outer preform 2 is formed by, for example, injection molding a biaxially stretchable polyethylene terephthalate (PET) resin. Examples of such a polyethylene terephthalate resin include homopolymer PET, etc., but other PETs such as IPA (isophthalic acid) modified PET or CHDM modified PET may also be used. The outer preform 2 is not limited to being made of a polyethylene terephthalate resin, and may be formed of other resin materials such as, for example, a polypropylene (PP) resin or a polyethylene (PE) resin. The outer preform 2 is not limited to a single-layer structure, and may have a multi-layer structure including one or more functional layers for improving functions such as barrier properties in addition to the main material layer.

[0023] The inner preform 3 has a cylindrical inner mouth portion 3a centered on the central axis O and a bottomed cylindrical inner body portion 3b extending downward from the lower end of the inner mouth portion 3a.

[0024] The portion of the inner mouth portion 3a excluding the lower end portion is not substantially stretched during biaxial stretch blow molding and has the same shape as the inner layer mouth portion 5a of the inner layer body 5. The inner mouth portion 3a has an inner mouth portion main body 3c located at the height from the upper end to the lower end of the outer mouth portion 2c, a flange 3d protruding radially outward from the upper end portion of the inner mouth portion main body 3c and forming an annular shape centered on the central axis O, and a cap engaging portion 3e extending upward from the upper end portion of the inner mouth portion main body 3c and forming a cylindrical shape centered on the central axis O, and as a whole forms a cylindrical shape centered on the central axis O. Note that the cap engaging portion 3e may be configured to extend upward from the flange 3d and form a cylindrical shape centered on the central axis O.

[0025] The inner mouth portion main body 3c has an upper region 3f in which the outer diameter and the inner diameter are constant in the vertical direction, and a lower region 3g whose diameter decreases downward from the lower end of the upper region 3f. The upper region 3f of the inner mouth portion main body 3c is located at the height from the upper end to the lower end of the upper portion 2g of the outer mouth portion 2c. The outer peripheral surface of the inner mouth portion main body 3c has a screwing portion 3h formed of a male screw portion centered on the central axis O only in the upper region 3f. The screwing portion 3h is screwed onto and detached from the screwed portion 2j. The lower surface of the flange 3d abuts against the seal protrusion 2f of the outer mouth portion 2c over the entire circumference.

[0026] Since at least the upper end of the lower region 3g of the inner mouth part body 3c is a non-stretched part that is not substantially stretched during biaxial stretch blow molding, as shown in FIG. 2, the lower end of the non-stretched part in the inner layer mouth part 5a extends radially inward from the inner surface of the outer layer body 4, and the part stretched from the tip of the non-stretched part adheres to the outer layer body 4. Therefore, a gap between the inner and outer layers is surely provided at the boundary between the stretched part and the non-stretched part. Thus, when the screwed part 3h of the double container 6 is screwed off upward from the part to be screwed 2j as described later, since the gap serves as a starting point for the peeling of the inner layer body 5 from the outer layer body 4, the separation operation becomes easy.

[0027] The inner barrel part 3b is stretched in two axial directions, the vertical direction (axial direction) and the radial direction, during biaxial stretch blow molding, and is formed into the inner layer barrel part 5b of the inner layer body 5. The inner barrel part 3b has an inner barrel part body 3i that extends downward while reducing the diameter from the lower end of the inner mouth part 3a, and a bottom part 3j that protrudes downward and closes the lower end of the inner barrel part body 3i. The inner barrel part body 3i reduces the diameter downward with a gradient smaller than that of the lower region 3g of the inner mouth part body 3c. The inner layer barrel part 5b has a bottomed cylindrical shape that extends downward from the lower end of the inner layer mouth part 5a. More specifically, it adheres to the inner surfaces of the shoulder region 4c, the bottom region 4d, and the barrel main body region 4e of the outer layer barrel part 4b.

[0028] The inner preform 3 is assembled inside the outer preform 2 by screwing the screwed part 3h onto the part to be screwed 2j so that the flange 3d is in contact with the seal protrusion 2f at the open end 2b of the outer preform 2 over the entire circumference. The seal protrusion 2f may be provided on the lower surface of the flange 3d instead of the open end 2b of the outer preform 2.

[0029] The male screw part constituting the screwed part 3h and the female screw part constituting the part to be screwed 2j may each be configured as a single-thread screw, a multi-thread screw of two or more threads, or an intermittent screw.

[0030] As shown in Fig. 1, it is preferable that there is a gap between the outer barrel portion 2d and the inner barrel portion 3b in the laminated preform 1. Note that the gap may be provided both between the outer barrel body 2k and the inner barrel body 3i and between the closed end 2a and the bottom portion 3j, or may be provided on either one of them. A configuration without providing the gap may also be adopted.

[0031] The cap engaging portion 3e can be engaged with the cap 7 so as to be rotatable together with the cap 7 in the screwing-off direction with respect to the outer layer body 4 or the outer preform 2. For this purpose, the outer peripheral surface of the cap engaging portion 3e has an uneven shape in which the radial height changes in the circumferential direction, and has a circumferential engaging portion 3k that can be engaged with the cap 7. Further, the outer peripheral surface of the cap engaging portion 3e has an uneven shape in which the radial height changes in the vertical direction in order to restrict the cap 7 from coming off upward from the cap engaging portion 3e, and has a vertical engaging portion 3l that can be engaged with the cap 7. The circumferential engaging portion 3k is composed of a plurality of protrusions 3m arranged in the circumferential direction on the vertical engaging portion 3l composed of an annular convex portion. Note that the vertical engaging portion 3l may be formed of an uneven shape other than the annular convex portion, and the circumferential engaging portion 3k may be formed of an uneven shape other than the plurality of protrusions 3m arranged in the circumferential direction on the vertical engaging portion 3l. Note that the cap 7 does not engage with the outer layer body 4 and engages only with the inner layer body 5 via the cap engaging portion 3e.

[0032] The inner preform 3 is formed, for example, by injection molding a polypropylene (PP) resin (regardless of whether it is a homopolymer, a random copolymer, or a block copolymer). The inner preform 3 is not limited to being made of a polypropylene resin, and can be appropriately selected from materials that enable the inner layer body 5 to be peeled off from the outer layer body 4. For example, it may be formed of a polyethylene (PE) resin or a biaxially stretchable polyethylene terephthalate resin. The inner preform 3 is not limited to a single-layer structure, and may have a multi-layer structure including one or more functional layers that improve functions such as barrier properties in addition to the main material layer.

[0033] In order to enhance the separability between the inner layer body 5 and the outer layer body 4, a layer made of silicon may be provided, for example, by coating on at least one of the outer surface of the inner layer body 5 and the inner surface of the outer layer body 4.

[0034] The above-mentioned laminated preform 1 is formed by the laminated preform 1 forming process, and can be formed into the double container 6 by further undergoing a blow molding process.

[0035] The laminated preform 1 forming process is a process of forming the laminated preform 1 (see FIG. 1) by assembling the inner preform 3 inside the outer preform 2 by removably screwing the screwing portion 3h to the screwed portion 2j on the inner surface of the outer preform 2 until the flange 3d abuts against the open end 2b of the outer preform 2. By configuring so that the flange 3d abuts against the open end 2b of the outer preform 2 in this way, the assembling accuracy of the inner preform 3 to the outer preform 2 can be improved, and it is also possible to suppress problems such as breakage due to over-screwing the inner preform 3 into the outer preform 2.

[0036] The blow molding process is a process of forming the double container 6 (see FIG. 2) having a shape along the cavity shape of the blow mold by disposing the laminated preform 1 in the blow mold and performing biaxial stretch blow molding.

[0037] The double container 6 can be formed into a discharge container 8 (see FIG. 3) by further undergoing a capping process, for example, after being filled with contents (not shown). The capping process is a process of attaching the cap 7 to the inner layer mouth portion 5a by engaging the cap 7 with the cap engaging portion 3e.

[0038] The cap 7 is configured as a discharge cap having a discharge port (not shown). More specifically, the cap 7 has a cap body 7a that engages with the cap engaging portion 3e and has a discharge port, and a lid body 7c that is rotatably connected to the cap body 7a via a hinge portion 7b (see FIG. 4) and can open and close the discharge port. Note that the lid body 7c may be provided separately from the cap body 7a. Also, the cap 7 is not limited to the configuration having the lid body 7c.

[0039] The discharge container 8 can discharge, as needed, for example, a liquid content accommodated in the internal space 9 of the double container 6 (more specifically, the inner layer barrel portion 5b) through the discharge port of the cap 7. Further, since the discharge container 8 has a screwing portion 3h, the inner layer body 5 can be easily separated from the outer layer body 4 when the content is used up. More specifically, the user holds and twists the cap 7 in the opened state (it may also be in the closed state) and the outer layer body 4 respectively, and as shown in FIG. 4, the cap 7 is rotated in the screwing and unscrewing direction with respect to the outer layer body 4 integrally with the inner layer mouth portion 5a by engagement through the cap engaging portion 3e, so that the inner layer body 5 can be peeled off from the outer layer body 4, pushed up against the outer layer body 4, and easily taken out from the inside of the outer layer body 4. Therefore, the discharge container 8 is particularly convenient when it is necessary to separate the inner layer body 5 in order to recycle the outer layer body 4, such as when the content is oil.

[0040] Also, in the discharge container 8, the space between the opening end 2b of the outer layer mouth portion 4a and the flange 3d is sealed by the seal ridge 2f. Therefore, the permeability of gases such as oxygen permeating from the external atmosphere into the space between the outer layer mouth portion 4a and the inner layer mouth portion 5a and into the internal space 9 through the inner layer body 5 can be suppressed, and as a result, the quality of the content in the discharge container 8 can be maintained well.

[0041] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof.

[0042] Therefore, the laminated preform 1 of the above-described embodiment has a bottomed cylindrical outer preform 2 and a bottomed cylindrical inner preform 3 having a flange 3d and a screwing portion 3h on the outer peripheral surface, and the inner preform 3 is assembled inside the outer preform 2 by screwing the screwing portion 3h onto the inner surface of the outer preform 2 so as to be screwing and unscrewing possible until the flange 3d abuts against the opening end 2b of the outer preform 2. As long as it is the laminated preform 1, it can be changed.

[0043] Further, the manufacturing method of the double container 6 of the above-described embodiment can be changed as long as it is a manufacturing method of the double container 6 having a laminated preform forming step of forming the laminated preform 1 by assembling a bottomed cylindrical inner preform 3 having a flange 3d and a screwing portion 3h on its outer peripheral surface inside a bottomed cylindrical outer preform 2 until the flange 3d abuts against the open end 2b of the outer preform 2 by screwing the screwing portion 3h detachably onto the inner surface of the outer preform 2, and a blow molding step of biaxially stretch blow molding the laminated preform 1.

[0044] Further, the double container 6 of the above-described embodiment can be changed as long as it is a double container 6 having a bottomed cylindrical outer layer body 4 and a bottomed cylindrical inner layer body 5 having a flange 3d and a screwing portion 3h on its outer peripheral surface, the inner layer body 5 being laminated inside the outer layer body 4 so as to be peelable from the outer layer body 4, the flange 3d abutting against the open end 2b of the outer layer body 4, and the screwing portion 3h being screwed detachably onto the inner surface of the outer layer body 4.

[0045] For example, the double container 6 may be configured as a laminated peelable container having an outside air inlet and capable of introducing outside air between the outer layer body 4 and the inner layer body 5 through the outside air inlet as the inner layer body 5 is reduced in volume and deformed due to peeling from the outer layer body 4. In this case, the outside air inlet may be configured, for example, as a through portion that radially penetrates the outer layer mouth portion 4a, as a gap provided between the open end 2b of the outer layer mouth portion 4a and the lower surface of the flange 3d, or as a through portion provided by post-processing after the double container 6 is molded and penetrating the outer layer body portion 4b. The cap 7 is not limited to a discharge cap having a discharge port, and may be configured, for example, as a mounting cap for attaching a pump having a discharge port to the inner layer mouth portion 5a. The outer layer body portion 4b is not limited to a shape having a shoulder region 4c. The inner preform 3 may be configured not to have a cap engaging portion 3e. The seal ridge 2f may not be provided.

[0046] In addition, in the above configuration, the laminated preform 1 of the above-described embodiment is preferably a laminated preform 1 in which the inner preform 3 has a cap engaging portion 3e that can engage with the cap 7 so as to be rotatable together with the cap 7 in the screwing-off direction with respect to the outer preform 2.

[0047] In the laminated preform 1 of the above-described embodiment, in the above configuration, it is preferable that the inner preform 3 is formed of polypropylene and the outer preform 2 is formed of polyethylene terephthalate.

[0048] In the laminated preform 1 of the above-described embodiment, in the above configuration, it is preferable that the laminated preform 1 has a seal protrusion 2f in which one of the flange 3d and the open end 2b of the outer preform 2 abuts against the other of the flange 3d and the open end 2b of the outer preform 2 over the entire circumference.

Explanation of Reference Numerals

[0049] 1 Laminated preform 2 Outer preform 2a Closed end 2b Open end 2c Outer mouth portion 2d Outer barrel portion 2e Open end face 2f Seal protrusion 2g Upper portion 2h Lower portion 2i Neck ring 2j Threaded portion 2k Outer barrel portion body 3 Inner preform 3a Inner mouth portion 3b Inner barrel portion 3c Inner mouth portion body 3d Flange 3e Cap engaging portion 3f Upper region 3g Lower region 3h Threaded portion 3i Inner barrel portion body 3j Bottom portion 3k Circumferential engaging portion 3l Vertical engaging portion 3m Protrusion 4 Outer layer body 4a Outer layer mouth portion 4b Outer layer barrel portion 4c Shoulder region 4d Bottom region 4e body main body area 5 inner layer body 5a inner layer mouth part 5b inner layer barrel part 6 double container 7 cap 7a cap body 7b hinge part 7c lid body 8 discharge container 9 internal space O central axis

Claims

1. A bottomed cylindrical outer preform having a screwed portion to be screwed formed by an internal thread portion on its inner peripheral surface, and a bottomed cylindrical inner preform having a screwed portion formed by a flange and an external thread portion on its outer peripheral surface, and the inner preform is assembled inside the outer preform by screw-engaging the external thread portion with the internal thread portion in a screwing-removable manner until the flange abuts against the open end of the outer preform and the upper surface of the external thread portion abuts against the lower surface of the internal thread portion. A laminated preform.

2. The inner preform has an inner mouth portion body, the inner mouth portion body has an upper region where the outer diameter and the inner diameter are constant in the vertical direction, and a lower region whose diameter is reduced downward from the lower end of the upper region, and the outer peripheral surface of the inner mouth portion body has the screwed portion only in the upper region, and at least the upper end portion of the lower region of the inner mouth portion body is a non-stretched portion that is not substantially stretched during biaxial stretch blow molding. The laminated preform according to claim 1.

3. The laminated preform according to claim 1 or 2, wherein the inner preform has a cap engaging portion that can engage with a cap so as to be rotatable with the cap in the screwing-removing direction with respect to the outer preform.

4. The inner preform is formed of polypropylene, and the outer preform is formed of polyethylene terephthalate. The laminated preform according to any one of claims 1 to 3.

5. A laminated preform forming step of assembling a bottomed cylindrical inner preform having a screwed portion formed by a flange and an external thread portion inside a bottomed cylindrical outer preform having a screwed portion to be screwed formed by an internal thread portion on its inner peripheral surface by screw-engaging the external thread portion with the internal thread portion in a screwing-removable manner until the flange abuts against the open end of the outer preform and the upper surface of the external thread portion abuts against the lower surface of the internal thread portion to form a laminated preform, and a blow molding step of biaxially stretch blow molding the laminated preform. A method for manufacturing a double container.

6. The inner preform has an inner mouth portion body, the inner mouth portion body has an upper region where the outer diameter and the inner diameter are constant in the vertical direction, and a lower region whose diameter is reduced downward from the lower end of the upper region, and the outer peripheral surface of the inner mouth portion body has the screwed portion only in the upper region, The manufacturing method of a double container according to claim 5, wherein at least the upper end portion of the lower side region of the inner mouth portion body is a non-stretched portion that is not substantially stretched during biaxial stretch blow molding.

Images