Laminated preform and method for manufacturing double container

Abstract

To provide a laminated preform capable of forming a double container in which an inner layer body can be easily separated from an outer layer body, and a manufacturing method of the double container.SOLUTION: A laminated preform 1 includes a bottomed cylindrical outer preform 2 and a bottomed cylindrical inner preform 3 having a flange 3d and a screw part 3h on its outer peripheral surface, and the inner preform 3 is assembled to the inside of the outer preform 2 by detachably screwing the screw part 3h to the inner surface of the outer preform 2 until the flange 3d comes into contact with an opening end 2b of the outer preform 2. A manufacturing method of a double container 6 includes: a laminated preform 1 formation process in which the laminated preform 1 is formed by assembling the bottomed cylindrical inner preform 3 having the flange 3d and the screw part 3h on its outer peripheral surface to the inside of the bottomed cylindrical outer preform 2 by detachably screwing the screw part 3h to the inner surface of the outer preform 2 until the flange 3d comes into contact with the opening end 2b of the outer preform 2; and a blow molding process for biaxially draw-blow-molding the laminated preform 1.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 technology]

[0002] A double container is known which has a cylindrical outer layer with a bottom and a cylindrical inner layer with a bottom, the inner layer being laminated inside the outer layer so as to be peelable from the outer layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2009-518245 Summary of the Invention [Problem to be solved by the invention]

[0004] From the viewpoint of recyclability, it is desirable that the inner layer of the double-layered container be easily separated from the outer layer.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a laminated preform and a method for manufacturing a double container, which are capable of forming a double container in which the inner layer can be easily separated from the outer layer. [Means for solving the problem]

[0006] The laminated preform of the present invention comprises a bottomed cylindrical outer preform and a bottomed cylindrical inner preform having a flange and a threaded portion on its outer peripheral surface, and the inner preform is assembled to the inside of the outer preform by threading the threaded portion into the inner surface of the outer preform in a detachable manner until the flange abuts against the open end of the outer preform. one of the flange and the open end of the outer preform has a sealing ridge abutting the other of the flange and the open end of the outer preform over the entire periphery; It is a laminated preform.

[0007] In the laminated preform of the present invention having the above-mentioned configuration, the inner preform preferably has a cap engaging portion that can be engaged with the cap and can rotate together with the cap in the screwing / unscrewing direction relative to the outer preform.

[0008] In the laminated preform of the present invention having the above-mentioned configuration, it is preferable that the inner preform is made of polypropylene and the outer preform is made of polyethylene terephthalate.

[0010] The method for producing a double container of the present invention includes a laminated preform forming step of assembling a bottomed cylindrical inner preform, which has a flange and a threaded portion on its outer peripheral surface, inside a bottomed cylindrical outer preform by threading the threaded portion into the inner surface of the outer preform in a detachable manner until the flange abuts against the open end of the outer preform, thereby forming a laminated preform; and a blow molding step of biaxially stretching and blow molding the laminated preform. one of the flange and the open end of the outer preform has a sealing ridge abutting the other of the flange and the open end of the outer preform over the entire periphery; A method for manufacturing a double container. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a laminated preform and a method for manufacturing a double container, which are capable of forming a double container in which the inner layer body can be easily separated from the outer layer body. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a partial cross-sectional side view showing a laminated preform according to one embodiment of the present invention. [Figure 2] 2 is a partial cross-sectional side view showing an example of a double container obtained by biaxially stretch blow molding the laminated preform shown in FIG. 1. FIG. [Figure 3] 3 is a partial cross-sectional side view showing an example of a discharge container having the double container shown in FIG. 2. FIG. [Figure 4] 4 is a partial cross-sectional side view showing how the inner layer body is separated from the outer layer body in the discharge container shown in FIG. 3. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] As shown in Fig. 1, in one embodiment of the present invention, a laminated preform 1 has a bottomed, tubular outer preform 2 centered on a central axis O, and a bottomed, tubular inner preform 3 coaxially assembled inside the outer preform 2. By biaxially stretch-blow molding the laminated preform 1, it is possible to mold a double container 6, as shown in Fig. 2, having a bottomed, tubular outer layer 4 centered on the central axis O, and a bottomed, tubular 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 container 6, it is possible to form a discharge container 8, as shown in Fig. 3, for example.

[0015] In this application, "peeling" refers not only to the case where the inner layer 5 and the outer layer 4 separate from each other from an adhesive state or a pseudo-adhesive state in which there is almost no adhesive force involved, but also to the case where the inner layer 5 and the outer layer 4 separate from each other from a tightly contacted state in which there is no adhesive force involved.

[0016] For ease of explanation, the direction along the central axis O is also referred to as the up-down direction, the direction from the closed end 2a toward the open end 2b of the outer preform 2 along the central axis O is also referred to as the up direction, and the opposite direction is also referred to as the down direction, the direction along a straight line perpendicular to the central axis O is also referred to as the radial direction, and the direction circumferentially around the central axis O is also referred to as the circumferential direction.

[0017] The outer preform 2 has a cylindrical outer opening 2c centered on the central axis O, and a cylindrical outer body 2d with a bottom that extends downward from the lower end of the outer opening 2c. The outer opening 2c may have an external appearance that is a regular polygon or other tubular shape other than a cylindrical shape.

[0018] The outer opening 2c is not substantially stretched during biaxial stretch blow molding and has the same shape as the outer layer opening 4a of the outer layer body 4. The opening end surface 2e (upper end surface) of the outer opening 2c has a ring-shaped sealing ridge 2f that protrudes upward and is centered on the central axis O. The outer opening 2c has an upper portion 2g whose outer and inner diameters are constant from the opening end 2b downward, a lower portion 2h whose outer and inner diameters are smaller than those of the upper portion 2g, and a ring-shaped neck ring 2i that protrudes radially outward at the boundary between the upper and lower portions 2g and 2h and is centered on the central axis O. In addition, the inner peripheral surface of the outer opening 2c has a threaded portion 2j consisting of an internal thread centered on the central axis O, only on the upper portion 2g.

[0019] The threaded portion 2j may be provided so as to straddle the upper portion 2g and the lower portion 2h, or may be provided only on the lower portion 2h. The lower portion 2h may be configured so that only the inner diameter or both the inner diameter and the outer diameter are equivalent to those of the upper portion 2g. A configuration without a neck ring 2i is also possible.

[0020] The outer body 2d is stretched in two directions, the vertical (axial) direction and the radial direction, during biaxial stretch blow molding to form the outer body 4b of the outer layer 4. The outer body 2d has an outer body main body 2k that extends downward from the lower end of the outer opening 2c while reducing in diameter, and a closed end 2a that has a convex shape that protrudes downward and closes the lower end of the outer body main body 2k. The outer body 4b has a bottomed tubular shape that extends downward from the lower end of the outer opening 4a, and more specifically has a shoulder region 4c that widens downward from the lower end of the outer opening 4a, a bottom region 4d including a ground contact portion, and a body main body region 4e that connects the shoulder region 4c and the bottom region 4d.

[0021] The outer preform 2 is formed by, for example, injection molding a biaxially stretchable polyethylene terephthalate (PET) resin. Examples of such polyethylene terephthalate resins include homo-PET, 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 made of other resin materials such as polypropylene (PP) resin or polyethylene (PE) resin. The outer preform 2 is not limited to a single-layer structure, but may have a multi-layer structure including, in addition to a main material layer, one or more functional layers that improve functions such as barrier properties.

[0022] The inner preform 3 has a cylindrical inner mouth portion 3a centered on the central axis O, and a cylindrical inner body portion 3b with a bottom that extends downward from the lower end of the inner mouth portion 3a.

[0023] The portion of the inner opening 3a excluding its lower end is not substantially stretched during biaxial stretch blow molding, and has the same shape as the inner layer opening 5a of the inner layer body 5. The inner opening 3a has an inner opening main body 3c located at a height from the upper end to the lower end of the outer opening 2c, an annular flange 3d centered on the central axis O and projecting radially outward from the upper end of the inner opening main body 3c, and a cylindrical cap engaging portion 3e extending upward from the upper end of the inner opening main body 3c and 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 also be configured to extend upward from the flange 3d and form a cylindrical shape centered on the central axis O.

[0024] The inner opening body 3c has an upper region 3f, whose outer and inner diameters 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 opening body 3c is located at the height from the upper end to the lower end of the upper part 2g of the outer opening 2c. The outer peripheral surface of the inner opening body 3c has a threaded portion 3h, consisting of a male thread portion centered on the central axis O, only in the upper region 3f. The threaded portion 3h is threadably and releasably engaged with the threaded portion 2j. The lower surface of the flange 3d abuts against the sealing ridge 2f of the outer opening 2c around the entire circumference.

[0025] Since at least the upper end of the lower region 3g of the inner opening body 3c is a non-stretched portion that is not substantially stretched during biaxial stretch blow molding, the lower end of the non-stretched 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 non-stretched portion adheres closely to the outer layer 4, ensuring the creation of a gap between the inner and outer layers at the boundary between the stretched and non-stretched portions. Therefore, when the threaded portion 3h of the double container 6 is unscrewed upward from the threaded portion 2j, as described below, the gap becomes the starting point for peeling of the inner layer 5 from the outer layer 4, facilitating the separation operation.

[0026] During biaxial stretch blow molding, the inner body 3b is stretched in two directions, the vertical (axial) direction and the radial direction, to form the inner body 5b of the inner layer body 5. The inner body 3b has an inner body main body 3i that extends downward from the lower end of the inner opening 3a while decreasing in diameter, and a bottom portion 3j that has a convex shape that protrudes downward and closes the lower end of the inner body main body 3i. The inner body main body 3i decreases in diameter downward at a smaller gradient than the lower region 3g of the inner opening main body 3c. The inner body 5b has a bottomed, tubular shape that extends downward from the lower end of the inner opening 5a, and more specifically, it is in close contact with the inner surfaces of the shoulder region 4c, bottom region 4d, and body main region 4e of the outer body 4b.

[0027] The inner preform 3 is assembled to the inside of the outer preform 2 by releasably screwing the threaded portion 3h into the threaded portion 2j until the flange 3d abuts against the sealing ridge 2f on the opening end 2b of the outer preform 2 over the entire circumference. The sealing ridge 2f may be provided on the underside of the flange 3d instead of on the opening end 2b of the outer preform 2.

[0028] 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 multiple-start thread with two or more starts, or an intermittent thread.

[0029] As shown in Fig. 1, the laminated preform 1 preferably has a gap between the outer body 2d and the inner body 3b. The gap may be provided both between the outer body main body 2k and the inner body main body 3i and between the closed end 2a and the bottom portion 3j, or may be provided in either one of these locations. A configuration without such a gap is also possible.

[0030] The cap engaging portion 3e can engage with the cap 7 so as to be rotatable together with the cap 7 in the screwing / removing direction relative to the outer layer body 4 or the outer preform 2. To this end, the outer peripheral surface of the cap engaging portion 3e has a concave-convex shape whose radial height varies in the circumferential direction and includes a circumferential engaging portion 3k that can engage with the cap 7. The outer peripheral surface of the cap engaging portion 3e also has a concave-convex shape whose radial height varies in the vertical direction and includes a vertical engaging portion 3l that can engage with the cap 7 to prevent the cap 7 from slipping out upward from the cap engaging portion 3e. The circumferential engaging portion 3k is composed of a plurality of protrusions 3m arranged circumferentially on the vertical engaging portion 3l, which is an annular convex portion. The vertical engaging portion 3l may be configured with a concave-convex shape other than an annular convex portion, and the circumferential engaging portion 3k may be configured with a concave-convex shape other than the plurality of protrusions 3m arranged circumferentially on the vertical engaging portion 3l. The cap 7 does not engage with the outer layer body 4, but only engages with the inner layer body 5 via the cap engaging portion 3e.

[0031] The inner preform 3 is formed, for example, by injection molding polypropylene (PP) resin (regardless of whether it is a homopolymer, random copolymer, or block copolymer). The inner preform 3 is not limited to being made of polypropylene resin, and can be appropriately selected from materials that allow the inner layer body 5 to be peeled from the outer layer body 4, and may be made, for example, of polyethylene (PE) resin or biaxially stretchable polyethylene terephthalate resin. The inner preform 3 is not limited to a single-layer structure, and may also have a multi-layer structure that includes, in addition to a main material layer, one or more functional layers that improve functions such as barrier properties.

[0032] In order to enhance the separation between the inner layer body 5 and the outer layer body 4, a layer made of silicon may be provided on at least one of the outer surface of the inner layer body 5 and the inner surface of the outer layer body 4, for example, by coating.

[0033] The laminated preform 1 is formed in the laminated preform 1 forming step, and can be molded into a double container 6 by further undergoing a blow molding step.

[0034] The laminated preform 1 formation process is a process for forming the laminated preform 1 (see FIG. 1 ) by assembling the inner preform 3 to the inside of the outer preform 2 by releasably screwing the threaded portion 3h into the threaded 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 the flange 3d to abut against the open end 2b of the outer preform 2 in this way, it is possible to increase the accuracy of assembling the inner preform 3 to the outer preform 2 and also to prevent problems such as breakage caused by over-threading the inner preform 3 into the outer preform 2.

[0035] The blow molding step is a step in which the laminated preform 1 is placed in a blow molding die and subjected to biaxial stretch blow molding to form a double container 6 (see FIG. 2) having a shape that conforms to the cavity shape of the blow molding die.

[0036] The double container 6 can be filled with a content (not shown), and then subjected to a capping process to form a discharge container 8 (see FIG. 3). The capping process is a process in which the cap 7 is attached to the inner opening portion 5a by engaging with the cap engaging portion 3e.

[0037] 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 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. Furthermore, the cap 7 is not limited to a configuration having the lid body 7c.

[0038] The dispensing container 8 can dispense liquid contents, for example, contained in the internal space 9 of the double container 6 (more specifically, the inner body portion 5b) through the dispensing opening of the cap 7 as needed. Furthermore, the dispensing container 8 has a threaded engagement portion 3h, which allows the inner layer 5 to be easily separated from the outer layer 4, for example, when the contents have been used up. More specifically, a user can grasp and twist the cap 7 and the outer layer 4 with the lid 7c open (or closed), and, as shown in FIG. 4, rotate the cap 7 together with the inner opening portion 5a in the unscrewing direction relative to the outer layer 4 through the engagement via the cap engagement portion 3e. This causes the inner layer 5 to peel off from the outer layer 4, lift it up against the outer layer 4, and easily be removed from inside the outer layer 4. Therefore, the dispensing container 8 is particularly useful when the inner layer 5 needs to be separated for recycling, such as when the contents are oil.

[0039] Furthermore, the discharge container 8 is sealed between the opening end 2b of the outer layer opening 4a and the flange 3d by the sealing rib 2f. Therefore, it is possible to suppress the permeability of gases such as oxygen that permeate 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, and as a result, it is possible to maintain the quality of the contents in the discharge container 8 in a good condition.

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

[0041] Therefore, the laminated preform 1 of the above-mentioned embodiment can be modified as long as it is a laminated preform 1 that has a bottomed cylindrical outer preform 2 and a bottomed cylindrical inner preform 3 having a flange 3d and a screw-threaded portion 3h on its outer surface, and the inner preform 3 is assembled inside the outer preform 2 by screwing the screw-threaded portion 3h into the inner surface of the outer preform 2 in a releasable manner until the flange 3d abuts the opening end 2b of the outer preform 2.

[0042] Furthermore, the manufacturing method of the double container 6 in the above-mentioned embodiment can be modified as long as it is a manufacturing method of the double container 6 that includes a laminated preform 1 formation process in which a bottomed cylindrical inner preform 3 having a flange 3d and a threaded portion 3h on its outer surface is assembled to the inside of a bottomed cylindrical outer preform 2 by threading the threaded portion 3h releasably onto the inner surface of the outer preform 2 until the flange 3d abuts the opening end 2b of the outer preform 2, thereby forming a laminated preform 1, and a blow molding process in which the laminated preform 1 is biaxially stretched and blow molded.

[0043] Furthermore, the double container 6 of the above-mentioned embodiment can be modified as long as it is a double container 6 that has a bottomed cylindrical outer layer 4 and a bottomed cylindrical inner layer 5 having a flange 3d and a screw-threaded portion 3h on its outer surface, where the inner layer 5 is laminated on the inside of the outer layer 4 so as to be peelable from the outer layer 4, the flange 3d abuts the opening end 2b of the outer layer 4, and the screw-threaded portion 3h is screwed into the inner surface of the outer layer 4 so as to be able to be unscrewed.

[0044] For example, the double container 6 may be configured as a peelable laminate container having an air inlet through which air can be introduced between the outer layer 4 and the inner layer 5 as the inner layer 5 shrinks and deforms due to peeling from the outer layer 4. In this case, the air inlet may be, for example, a through-hole penetrating the outer layer opening 4a in the radial direction, a gap provided between the opening end 2b of the outer layer opening 4a and the underside of the flange 3d, or a through-hole provided by post-processing through the outer layer body 4b after molding the double container 6. The cap 7 is not limited to a discharge cap having a discharge port, but may also be configured as an attachment cap for attaching a pump having a discharge port to the inner layer opening 5a. The outer layer body 4b is not limited to a shape having a shoulder region 4c. The inner preform 3 may not have a cap engaging portion 3e. The seal ridge 2f may not be provided.

[0045] In addition, it is preferable that the laminated preform 1 of the above-mentioned embodiment is a laminated preform 1 in the above configuration, in which the inner preform 3 has a cap engagement portion 3e that can engage with the cap 7 so as to be rotatable together with the cap 7 in the screw-unscrewing direction relative to the outer preform 2.

[0046] The laminated preform 1 of the above-described embodiment is preferably a laminated preform 1 in which the inner preform 3 is made of polypropylene and the outer preform 2 is made of polyethylene terephthalate in the above configuration.

[0047] The laminated preform 1 of the above-described embodiment is preferably a laminated preform 1 in which, in the above configuration, one of the flange 3d and the opening end 2b of the outer preform 2 has a sealing ridge 2f that abuts the other of the flange 3d and the opening end 2b of the outer preform 2 over the entire circumference. [Explanation of symbols]

[0048] 1. Laminated preform 2. Outer preform 2a Closed end 2b Open end 2c External opening 2d outer body 2e Open end surface 2f Seal ridge 2g upper part 2h lower part 2i neck ring 2j Threaded part 2k outer body 3 Inner 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 layer body 4c shoulder area 4d bottom area 4e Body area 5 Inner layer 5a Inner layer mouth 5b Inner layer body 6 double container 7 Cap 7a Cap body 7b Hinge part 7c Lid body 8 Discharge container 9. Interior Space O center axis

Claims

1. a cylindrical outer preform with a bottom; a bottomed cylindrical inner preform having a flange and a threaded portion on its outer circumferential surface, the inner preform is assembled to the inside of the outer preform by releasably threading the threaded portion onto the inner surface of the outer preform until the flange abuts against the open end of the outer preform; a laminated preform, wherein one of the flange and the open end of the outer preform has a sealing ridge that abuts the other of the flange and the open end of the outer preform over the entire periphery;

2. 2. The laminated preform according to claim 1, wherein the inner preform has a cap engaging portion that can be engaged with the cap so as to be rotatable together with the cap in the screwing / removing direction relative to the outer preform.

3. the inner preform is made of polypropylene; 3. The laminate preform according to claim 1, wherein the outer preform is made of polyethylene terephthalate.

4. a laminated preform forming step of assembling a bottomed cylindrical inner preform, the inner preform having a flange and a threaded portion on its outer peripheral surface, to the inside of a bottomed cylindrical outer preform by threading the threaded portion onto the inner surface of the outer preform in a detachable manner until the flange abuts against the open end of the outer preform; a blow molding step of biaxially stretching and blow molding the laminated preform, A method for manufacturing a double container, wherein one of the flange and the open end of the outer preform has a sealing ridge that abuts the other of the flange and the open end of the outer preform over the entire circumference.

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