Laminated preform and method for manufacturing a double-walled 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 and a bottomed cylindrical inner layer, with the inner layer laminated inside the outer layer so as to be peelable from the outer layer, 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] [[ID=^{}35]]From the viewpoint of recyclability and the like, it is desirable that the inner layer can be easily separated from the outer layer in such a double container.

[0005] [[ID=^{}38]] 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 can be easily separated from the outer layer.

Means for Solving the Problems

[0006] The laminated preform of the present invention has a bottomed cylindrical outer preform having a screwed portion consisting of an internal thread portion on its inner peripheral surface, and a bottomed cylindrical inner preform having a flange and a screwed portion consisting of an external thread portion on its outer peripheral surface, and the inner preform is assembled inside the outer preform by screwing the external thread portion into the internal thread portion so as to be detachable 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.

[0007] In the laminated preform of the present invention, in the above configuration, the inner preform has an inner opening body, the inner opening body has an upper region in which the outer diameter and inner diameter are constant in the vertical direction, and a lower region in which the diameter decreases downward from the lower end of the upper region, the outer circumferential surface of the inner opening body has the threaded portion only in the upper region, and at least the upper end of the lower region of the inner opening body is an unstretched portion that is not substantially stretched during biaxial stretch blow molding, which is preferable for the laminated preform.

[0008] In the laminated preform of the present invention, it is preferable that the inner preform has a cap engagement portion that can engage with the outer preform so as to be able to rotate together with the cap in the unscrewing direction.

[0009] In the above configuration, the laminated preform of the present invention is preferably a laminated preform in which the inner preform is made of polypropylene and the outer preform is made of polyethylene terephthalate.

[0010] The present invention provides a method for manufacturing a double-walled container, comprising: a laminated preform forming step, in which a laminated preform is formed by assembling a bottomed cylindrical inner preform having a flange and a threaded portion consisting of a male thread on its outer circumferential surface into the inside of a bottomed cylindrical outer preform having a threaded portion consisting of a female thread on its inner circumferential surface, by screwing the male thread into the female thread so that the flange abuts against the open end of the outer preform and the upper surface of the male thread abuts against the lower surface of the female thread; and a blow molding step, in which the laminated preform is biaxially stretched blow molded.

[0011] The present invention provides a method for manufacturing a double-walled container, wherein, in the above configuration, the inner preform has an inner opening body, the inner opening body has an upper region in which the outer diameter and inner diameter are constant in the vertical direction, and a lower region in which the diameter decreases downward from the lower end of the upper region, the outer circumferential surface of the inner opening body has the threaded portion only in the upper region, and at least the upper end of the lower region of the inner opening body is an unstretched portion that is not substantially stretched during biaxial stretch blow molding. [Effects of the Invention]

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

[0013] [Figure 1] This is a partial cross-sectional side view showing a laminated preform of one embodiment of the present invention. [Figure 2] Figure 1 is a partial cross-sectional side view showing an example of a double-walled container obtained by biaxial stretch blow molding of the laminated preform shown in Figure 1. [Figure 3] Figure 2 is a partial cross-sectional side view showing an example of a discharge container having a double-walled container. [Figure 4] Figure 3 is a partial cross-sectional side view showing how the inner layer is separated from the outer layer in the discharge container shown. [Modes for carrying out the invention]

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

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

[0016] Furthermore, in this application, "detachment" includes not only cases where the inner layer 5 and the outer layer 4 separate from an adhesive state or a pseudo-adherent state in which little or no adhesive force is involved, but also cases where the inner layer 5 and the outer layer 4 separate from an adhering state in which no adhesive force is involved.

[0017] For the sake of explanation, the direction along the central axis O is also called the up-down 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 called the upward direction, the opposite direction is also called the downward direction, the direction along a straight line perpendicular to the central axis O is also called the radial direction, and the direction around the central axis O is also called the circumferential direction.

[0018] The outer preform 2 has a cylindrical outer opening 2c centered on the central axis O, and a bottomed cylindrical outer body 2d extending downward from the lower end of the outer opening 2c. The outer opening 2c may have a cylindrical shape other than a regular polygon, for example.

[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 screwed portion 2j that is a female screw portion centered on the central axis O only in the upper portion 2g.

[0020] Note that the screwed portion 2j may be provided so as to straddle from the upper portion 2g to the lower portion 2h, or the screwed portion 2j may be provided only in the lower portion 2h. The lower portion 2h may have the same inner diameter or both the inner diameter and the outer diameter as those of the upper portion 2g. 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 its 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 polyethylene terephthalate resin, and may be formed of other resin materials such as, for example, polypropylene (PP) resin or 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 shrinks 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 to and detached from the screwed portion 2j. The lower surface of the flange 3d abuts against the seal ridge 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 opening body 3c is an unstretched portion that is not substantially stretched during biaxial stretch blow molding, as shown in Figure 2, the lower end of the unstretched portion in the inner layer opening 5a extends radially inward from the inner surface of the outer layer 4, and the portion stretched from the tip of the unstretched portion adheres closely to the outer layer 4, a gap between the inner and outer layers is reliably provided at the boundary between the stretched portion and the unstretched portion. Therefore, as described later, when unscrewing the threaded portion 3h of the double container 6 upward from the threaded portion 2j, this gap becomes the starting point for peeling the inner layer 5 from the outer layer 4, making the separation operation easier.

[0027] The inner body portion 3b is stretched in two axial directions, vertical (axial) and radial, during biaxial stretch blow molding, and is formed into the inner body portion 5b of the inner layer body 5. The inner body portion 3b has an inner body body 3i that extends downward from the lower end of the inner opening portion 3a while decreasing in diameter, and a bottom portion 3j that is convex in shape and protrudes downward, closing the lower end of the inner body body 3i. The inner body body 3i decreases in diameter downward at a smaller gradient than the lower region 3g of the inner opening portion 3c. The inner body portion 5b is a bottomed cylindrical shape that extends downward from the lower end of the inner layer opening portion 5a, and more specifically, it is in close contact with the inner surfaces of the shoulder region 4c, bottom region 4d and body body region 4e of the outer body portion 4b.

[0028] The inner preform 3 is assembled to the inside of the outer preform 2 by screwing the threaded portion 3h into the threaded portion 2j so that the flange 3d abuts the sealing projection 2f of the open end 2b of the outer preform 2 all the way around. The sealing projection 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 thread portion constituting the threaded portion 3h and the female thread portion constituting the threaded portion 2j may each be configured as a single-start thread, a multi-start thread with two or more starts, or an intermittent thread.

[0030] As shown in Figure 1, it is preferable that the laminated preform 1 has a gap between the outer shell 2d and the inner shell 3b. This gap may be provided both between the outer shell body 2k and the inner shell body 3i, and between the closed end 2a and the bottom portion 3j, or it may be provided in only one of them. A configuration without such a gap is also possible.

[0031] The cap engagement portion 3e is capable of engaging with the cap 7 so as to be able to rotate together with the cap 7 in the unscrew direction relative to the outer layer 4 or outer preform 2. For this purpose, the outer circumferential surface of the cap engagement portion 3e has an uneven surface in which the radial height changes in the circumferential direction, and has a circumferential engagement portion 3k that can engage with the cap 7. In addition, the outer circumferential surface of the cap engagement portion 3e has an uneven surface in which the radial height changes in the vertical direction, and has a vertical engagement portion 3l that can engage with the cap 7, in order to restrict the cap 7 from coming out upward from the cap engagement portion 3e. The circumferential engagement portion 3k consists of a plurality of protrusions 3m arranged in the circumferential direction on the vertical engagement portion 3l, which consists of an annular protrusion. The vertical engagement portion 3l may be composed of an uneven surface shape other than an annular protrusion, and the circumferential engagement portion 3k may be composed of an uneven surface shape other than the plurality of protrusions 3m arranged in the circumferential direction on the vertical engagement portion 3l. The cap 7 does not engage with the outer layer 4, but engages only with the inner layer 5 via the cap engagement portion 3e.

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

[0033] To improve the separation between the inner layer 5 and the outer layer 4, a layer made of silicon may be provided on at least one of the outer surface of the inner layer 5 and the inner surface of the outer layer 4, for example, by coating.

[0034] The laminated preform 1 described above is formed by the laminated preform 1 formation process and can be further molded into a double-walled container 6 by going through a blow molding process.

[0035] The laminated preform 1 formation process involves assembling the inner preform 3 to the inside of the outer preform 2 by screwing the threaded portion 3h into the threaded portion 2j on the inner surface of the outer preform 2 in a retractable manner until the flange 3d abuts against the open end 2b of the outer preform 2. This process forms the laminated preform 1 (see Figure 1). By configuring the flange 3d to abut against the open end 2b of the outer preform 2 in this way, the accuracy of assembling the inner preform 3 to the outer preform 2 can be improved, and problems such as damage caused by over-screwing the inner preform 3 into the outer preform 2 can be suppressed.

[0036] The blow molding process involves placing the laminated preform 1 inside a blow mold and performing biaxial stretch blow molding to form a double-walled container 6 (see Figure 2) that conforms to the cavity shape of the blow mold.

[0037] The double-walled container 6 can be further transformed into a dispensing container 8 (see Figure 3) by undergoing a capping process after, for example, the contents (not shown) have been filled. The capping process involves attaching the cap 7 to the inner opening 5a by engaging it with the cap engagement 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 engagement portion 3e and has a discharge port, and a lid 7c that is rotatably connected to the cap body 7a via a hinge portion 7b (see Figure 4) and can open and close the discharge port. Note that the lid 7c may be provided separately from the cap body 7a. Furthermore, the cap 7 is not limited to having a lid 7c.

[0039] The dispensing container 8 can dispense, for example, liquid contents contained in the internal space 9 of the double container 6 (more specifically, the inner layer body 5b) through the dispensing port of the cap 7 as needed. Furthermore, since the dispensing container 8 has a screw-on portion 3h, the inner layer 5 can be easily separated from the outer layer 4 when the contents are used up. More specifically, the user can grasp the cap 7 and the outer layer 4 with the lid 7c open (or closed) and twist them, as shown in Figure 4, to rotate the cap 7 in the unscrew direction relative to the outer layer 4, together with the inner layer opening 5a, through engagement via the cap engagement portion 3e. This separates the inner layer 5 from the outer layer 4, causing it to rise relative to the outer layer 4 and be easily removed from the inside of the outer layer 4. Therefore, the dispensing container 8 is particularly convenient when the contents are oil, for example, and it is necessary to separate the inner layer 5 in order to recycle the outer layer 4.

[0040] Furthermore, the discharge container 8 is sealed between the open end 2b of the outer layer opening 4a and the flange 3d by a sealing ridge 2f. Therefore, the permeability of gases such as oxygen from the external atmosphere into the internal space 9 through the space between the outer layer opening 4a and the inner layer opening 5a and the inner layer 5 can be suppressed, and as a result, the quality of the contents inside the discharge container 8 can be maintained in good condition.

[0041] The present invention is not limited to the embodiments described above, and can be modified in various ways without departing from its essence.

[0042] Therefore, the laminated preform 1 of the above-described embodiment is modifiable as long as it is a laminated preform 1 having a bottomed cylindrical outer preform 2 and a bottomed cylindrical inner preform 3 having a flange 3d and a threaded portion 3h on its outer surface, and the inner preform 3 is assembled inside the outer preform 2 by screwing the threaded portion 3h into the inner surface of the outer preform 2 in a way that allows it to be unscrewed until the flange 3d abuts against the open end 2b of the outer preform 2.

[0043] Furthermore, the manufacturing method for the double-walled container 6 of the above-described embodiment can be modified as long as it includes a laminated preform 1 forming step, in which a laminated preform 1 is formed by assembling a bottomed cylindrical inner preform 3 having a flange 3d and a threaded portion 3h on its outer circumferential surface into the inside of a bottomed cylindrical outer preform 2, by screwing the threaded portion 3h onto the inner surface of the outer preform 2 in a way that allows it to be unscrewed until the flange 3d abuts against the open end 2b of the outer preform 2, and a blow molding step of biaxially stretch blow molding the laminated preform 1.

[0044] Furthermore, the double-walled container 6 of the above-described embodiment is modifiable as long as it is a double-walled container 6 having a bottomed cylindrical outer layer 4 and a bottomed cylindrical inner layer 5 having a flange 3d and a threaded portion 3h on its outer surface, wherein the inner layer 5 is laminated on the inside of the outer layer 4 so as to be detachable from the outer layer 4, the flange 3d abuts against the open end 2b of the outer layer 4, and the threaded portion 3h is screwed into the inner surface of the outer layer 4 so as to be detachable.

[0045] For example, the double-walled container 6 may be configured as a laminated delamination container having an outside air inlet and allowing outside air to be introduced between the outer layer 4 and the inner layer 5 from the outside air inlet as the volume of the inner layer 5 deforms due to delamination from the outer layer 4. In this case, the outside air inlet may be configured as a through-hole that penetrates the outer layer opening 4a radially, or as a gap provided between the open end 2b of the outer layer opening 4a and the lower surface of the flange 3d, or as a through-hole that penetrates the outer layer body 4b and is provided by post-processing after the double-walled container 6 is formed. The cap 7 is not limited to a discharge cap having a discharge port, but may be configured as a mounting cap for attaching a pump having a discharge port to the inner layer opening 5a, for example. The outer layer body 4b is not limited to a shape having a shoulder region 4c. The inner preform 3 may be configured without a cap engagement portion 3e. The sealing ridge 2f may be omitted.

[0046] In addition, in the above-described embodiment, it is preferable that the laminated preform 1 is such that the inner preform 3 has a cap engagement portion 3e that can engage with the cap 7 so as to be able to rotate together with the cap 7 in the unscrew direction relative to the outer preform 2.

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

[0048] In the above-described embodiment, it is preferable that the laminated preform 1 has a sealing projection 2f that abuts the other flange 3d and the open end 2b of the outer preform 2 around its entire circumference. [Explanation of symbols]

[0049] 1. Laminated preform 2. Outer preform 2a Closed end 2b Open end 2c External opening 2d Outer shell 2e Open end surface 2f Seal protrusion 2g upper part 2h lower part 2i Neck Ring 2j Threaded part 2k Outer body 3. Internal preform 3a Inner mouth 3b Inner body 3c Inner mouth body 3D flange 3e Cap engagement part 3f upper area 3g lower area 3h threaded part 3i Inner Body 3j bottom part 3k Circumferential engagement part 3l Vertical engagement part 3m protrusion 4 Outer body 4a Outer layer mouth 4b Outer shell 4c shoulder area 4d bottom area 4e Torso main body area 5. Inner layer 5a Inner opening 5b Inner layer of the body 6 double container 7 caps 7a Cap body 7b Hinge section 7c Lid body 8 Discharge container 9 Interior space O center axis

Claims

1. A bottomed cylindrical outer preform having a threaded portion on its inner surface, and It has a bottomed cylindrical inner preform having a flange and a threaded portion consisting of a male thread on its outer surface, A laminated preform in which the inner preform is assembled inside the outer preform by screwing the male threaded portion into the female threaded portion in a removable manner 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.

2. The aforementioned internal preform has an internal opening body, The inner opening body has an upper region in which the outer diameter and inner diameter are constant in the vertical direction, and a lower region in which the diameter decreases downward from the lower end of the upper region. The outer circumferential surface of the inner opening body has the threaded portion only in the upper region, The laminated preform according to claim 1, wherein at least the upper end of the lower region of the inner opening body is an unstretched portion that is not substantially stretched during biaxial stretch blow molding.

3. The laminated preform according to claim 1 or 2, wherein the inner preform has a cap engagement portion that can engage with the cap so as to be rotatable with the cap in the unscrew direction relative to the outer preform.

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

5. A laminated preform is formed by assembling a bottomed cylindrical inner preform, having a flange and a threaded portion consisting of a male thread on its outer circumference, into the inside of a bottomed cylindrical outer preform, having a threaded portion consisting of a female thread on its inner circumference, by screwing the male thread into the female thread so that the flange abuts against the open end of the outer preform and the upper surface of the male thread abuts against the lower surface of the female thread, thereby forming a laminated preform. A method for manufacturing a double-walled container, comprising a blow molding step of biaxially stretch blow molding the laminated preform.

6. The aforementioned internal preform has an internal opening body, The inner opening body has an upper region in which the outer diameter and inner diameter are constant in the vertical direction, and a lower region in which the diameter decreases downward from the lower end of the upper region. The outer circumferential surface of the inner opening body has the threaded portion only in the upper region, The method for manufacturing a double container according to claim 5, wherein at least the upper end of the lower region of the inner opening body is a non-stretched portion that is not substantially stretched during biaxial stretch blow molding.

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