Preform for double container forming

Abstract

To suppress difficulty in fitting a mouth part of an inner preform into the mouth part of an outer preform despite a crystallized region provided in the inner preform.SOLUTION: A preform for molding a double container includes: a bottomed cylindrical inner preform 11 for molding an inner container X1; and a bottomed cylindrical outer preform 12 for molding an outer container X2. The inner preform is inserted into the outer preform with a mouth part 21 of the inner preform fitted in a mouth part 22 of the outer preform. The inner preform is made of crystalline resin. In the inner preform, a crystallized region 16 having a higher degree of crystallinity than other portions is provided at least in a portion adjacent to the mouth part from below and located below an outside air introduction hole 13. A step part 19 facing upward and a rib 27 extending upward from the step part are formed on an inner peripheral surface of the inner preform. At least part of the rib is adjacent to the crystallized region from above.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] A double container includes an inner container that is reduced in volume and deformed as the contained content decreases, and an outer container in which the inner container is housed. A preform for forming the double container is provided with an outside air introduction hole for introducing outside air between the inner container and the outer container as the content decreases. The preform includes a bottomed cylindrical inner preform for forming the inner container and a bottomed cylindrical outer preform for forming the outer container. As a preform of this type of double container, for example, as shown in Patent Document 1 below, with the mouth portion of the inner preform fitted inside the mouth portion of the outer preform, the inner preform is inserted into the outer preform. The inner preform is formed of a crystalline resin, and in the inner preform, at least a portion that is adjacent to the mouth portion from below the mouth portion and is located below the outside air introduction hole is provided with a crystallization region having a higher degree of crystallinity than other portions. In this preform, when compressed air is blown into the inner preform and blow molding is performed to form a double container, the crystallization region is less likely to expand toward the outer side in the radial direction, and it becomes easier to secure the vertical air passage of the portion located below the outside air introduction hole between the inner container and 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 double container molding, when providing a crystallization region by heating in the inner preform, the portion (hereinafter referred to as the adjacent portion) that is continuous from above the crystallization region with respect to the crystallization region thermally expands, and there is a case where it becomes difficult to fit the mouth portion of the inner preform into the mouth portion of the outer preform.

[0005] The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a preform for double container molding that can suppress the difficulty of fitting the mouth portion of the inner preform into the mouth portion of the outer preform even when a crystallization region is provided in the inner preform.

Means for Solving the Problems

[0006] The present invention employs the following means to solve the above problems. That is, the preform for double container molding of the present invention includes an inner container that undergoes volume reduction deformation as the content to be accommodated decreases, and an outer container in which the inner container is installed. Along with the decrease in the content, it is a preform for molding a double container provided with an outside air introduction hole for introducing outside air between the inner container and the inner container. It includes a bottomed cylindrical inner preform for molding the inner container and a bottomed cylindrical outer preform for molding the outer container. With the mouth portion of the inner preform fitted into the mouth portion of the outer preform, the inner preform is inserted into the outer preform. The mouth part of the preform is composed of the mouth part of the outer preform and the mouth part of the inner preform, and the outside air introduction hole is provided in the mouth part of the preform. The inner preform is formed of a crystalline resin. In the inner preform, at least a portion that is adjacent to the mouth portion from below the mouth portion and is located below the outside air introduction hole is knot is provided with a crystallization region. The crystallinity of the crystallization region is greater than the crystallinity of the portion of the inner preform other than the crystallization region. On the inner peripheral surface of the inner preform, a stepped portion facing upward and a rib extending upward from the stepped portion are formed, and at least a part of the rib is adjacent to the crystallization region from above the crystallization region.

[0007] Ribs are formed on the inner peripheral surface of the inner preform, and at least a part of the ribs is adjacent to the crystallization region from above the crystallization region. Therefore, in the inner preform, the rigidity of the portion (hereinafter referred to as the adjacent portion) that is continuous with the crystallization region from above the crystallization region is increased. When providing the crystallization region, even if the inner preform is heated, it is possible to suppress the adjacent portion from expanding outward in the radial direction, and it is possible to suppress the mouth portion of the inner preform from being difficult to fit into the mouth portion of the outer preform. Since the rib extends upward from the stepped portion facing upward, the preform for double container molding having the rib can be easily injection molded.

[0008] The rib may be separated downward from the upper end portion of the mouth portion of the inner preform.

[0009] Since the rib is separated downward from the upper end portion of the mouth portion of the inner preform, when transporting the preform for double container molding or the double container in the factory, a jig can be inserted into the upper end portion of the mouth portion, and the jig can be pressed against the inner peripheral surface of the upper end portion of the mouth portion.

[0010] The lower end portion of the rib may be located in the crystallization region.

[0011] Since the lower end portion of the rib is located in the crystallization region, the rib straddles at least the upper end portion of the crystallization region in the vertical direction, and the rigidity of the adjacent portion can be surely increased.

Advantages of the Invention

[0012] According to this invention, even if a crystallization region is provided in the inner preform, it is possible to suppress the mouth portion of the inner preform from being difficult to fit into the mouth portion of the outer preform.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0014] Hereinafter, with reference to the drawings, a preform for forming a double container according to an embodiment will be described. As shown in FIGS. 1 and 2, the preform 1 for forming a double container includes an inner container X1 that undergoes volume reduction deformation as the content accommodated therein decreases, and an outer container X2 in which the inner container X1 is installed. Along with the decrease in the content, it is used to form a double container X provided with an outside air introduction hole 13 for introducing outside air between the inner container X1. The double container X is formed by blowing compressed air into an inner preform 11 described later and 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 separably on the inner surface of the outer container X2.

[0015] 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. With the mouth portion (hereinafter referred to as the inner mouth portion) 21 of the inner preform 11 fitted into the mouth portion (hereinafter referred to as the outer mouth portion) 22 of the outer preform 12, the bottom portion (hereinafter referred to as the inner bottom portion) 23 of the inner preform 11 is inserted into the bottom portion (hereinafter referred to as the outer bottom portion) 24 of the outer preform 12.

[0016] 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 portion 21 and the outer mouth portion 22 along the central axis O is referred to as the upper side, and the side of the inner bottom portion 23 and the outer bottom portion 24 along the central axis O is referred to as the lower side. When viewed from the up-down 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.

[0017] The materials of the inner preform 11 and the outer preform 12 are synthetic resin materials, which may be of the same material or different materials from each other. As an example of the synthetic resin material, for example, PET (polyethylene terephthalate), PP (polypropylene), PE (polyethylene), nylon (polyamide), and EVOH (ethylene-vinyl alcohol copolymer), etc. may be mentioned. In the illustrated example, the inner preform 11 and the outer preform 12 are each formed of PET.

[0018] The inner preform 11 is formed of a crystalline resin. The crystalline resin contains an amorphous part in which the molecular chains are in an irregular state and a crystalline part in which the molecular chains are regularly arranged. As the content ratio of the crystalline part increases, the degree of crystallinity increases. The degree of crystallinity mainly depends on the cooling rate after heating. The degree of crystallinity can be measured, for example, by a density method, an X-ray diffraction method, a differential scanning calorimeter, an FT-IR method, or a solid NMR method, etc.

[0019] On the outer peripheral surface of the outer mouth part 22, a locking protrusion 22a into which a cap (not shown) is undercut-fitted, a sealing protrusion 22b onto which the peripheral wall part of a cap (not shown) is externally fitted, and a neck ring 22c, are formed in this order from above downward. Incidentally, the cap may be screwed onto the outer mouth part 22.

[0020] The locking protrusion 22a, the sealing protrusion 22b, and the neck ring 22c protrude radially outward from the outer mouth part 22 and continuously extend over the entire circumferential length. An airtight seal is provided between the outer peripheral surface of the sealing protrusion 22b and the inner peripheral surface of the peripheral wall part of a cap (not shown). The outer diameter of the neck ring 22c is larger than the outer diameters of the locking protrusion 22a and the sealing protrusion 22b. The neck ring 22c is located below the peripheral wall part of a cap (not shown).

[0021] The above-mentioned outside air introduction hole 13 is formed in the outer mouth part 22. The outside air introduction hole 13 is provided between the locking protrusion 22a and the sealing protrusion 22b. On the inner peripheral surface of the outer mouth portion 22, a vertical groove 14 extending downward from the upper end opening edge 15 of the outer preform 12 is formed. An outside air introduction hole 13 opens into the vertical groove 14. The lower end portion of the vertical groove 14 is located below the neck ring 22c. The outer mouth portion 22 is a portion of the outer preform 12 that includes the same position in the vertical direction as and is located above the lower surface of the neck ring 22c.

[0022] The inner mouth portion 21 is a portion of the inner preform 11 that is fitted inside the outer mouth portion 22. That is, the inner mouth portion 21 is a portion of the inner preform 11 that includes the same position in the vertical direction as and is located above the lower surface of the neck ring 22c in the outer preform 12. The outer peripheral surface of the inner mouth portion 21 is in contact with the inner peripheral surface of the outer mouth portion 22 over the entire length in the vertical direction. The inner mouth portion 21 is provided with a flange portion 25 that extends continuously over the entire circumferential length and abuts against the upper end opening edge 15 of the outer preform 12. An outside air introduction hole 13 may be provided between the lower surface of the flange portion 25 and the upper end opening edge 15 of the outer preform 12.

[0023] On the outer peripheral surface of the inner mouth portion 21, a ridge portion 26 is provided that protrudes radially outward, extends continuously over the entire circumferential length, and is in pressure contact with the inner peripheral surface of the outer mouth portion 22. A plurality of ridge portions 26 are provided at intervals in the vertical direction. The ridge portions 26 are located above the outside air introduction hole 13 of the outer mouth portion 22. Note that the ridge portions 26 may not be provided.

[0024] Here, in the inner preform 11, at least in a portion that is adjacent to the inner mouth portion 21 from below the inner mouth portion 21 and is located below the outside air introduction hole 13, a crystallization region 16 having a higher degree of crystallinity than other portions is provided.

[0025] In the inner preform 11, in the crystallization region 16, the light transmittance is lower than that of other parts. In the inner preform 11, in the crystallization region 16, the longitudinal elastic modulus is larger than that of other parts. The crystallization region 16 is a thermally crystallized region with an increased degree of crystallinity due to heating. The crystallization region 16 extends continuously over the entire circumferential length. The crystallization region 16 is separated downward from the inner mouth portion 21. Note that the crystallization region 16 may be provided, for example, at the inner mouth portion 21 or the like.

[0026] In the inner preform 11, a portion that includes the same position in the vertical direction as the upper edge of the crystallization region 16 and is located above is a non-stretched region 28 that does not stretch during blow molding. The vertical size of the crystallization region 16 is larger than the vertical interval between the upper edge of the crystallization region 16 and the lower edge of the inner mouth portion 21, and smaller than the vertical size of the non-stretched region 28. Note that the magnitude relationship of these vertical sizes may be changed as appropriate. The crystallization region 16 may be provided in the non-stretched region 28, or may be provided across the non-stretched region 28 and the stretched region located below the non-stretched region 28.

[0027] In the illustrated example, an outer rib 17 that protrudes radially outward is provided on the outer peripheral surface of the crystallization region 16. The outer rib 17 secures a vertical air passage between the outer peripheral surface of the inner container X1 and the inner peripheral surface of the outer container X2 in the double container X. The upper end portion of the outer rib 17 is located above the crystallization region 16, and the lower end portion of the outer rib 17 is located below the crystallization region 16. The outer rib 17 is in contact with the inner peripheral surface of the outer preform 12. A plurality of outer ribs 17 are provided at intervals in the circumferential direction.

[0028] A first stepped portion 18 facing downward is formed on the outer peripheral surface of the inner preform 11, and the outer rib 17 extends downward from the first stepped portion 18. The first stepped portion 18 extends upward as it goes radially outward. Note that the outer rib 17 may be radially inwardly spaced from the inner peripheral surface of the outer preform 12. The outer rib 17 may be provided in the crystallization region 16 over the entire vertical length. The outer rib 17 may be provided at a position vertically spaced from the crystallization region 16. The outer rib 17 may be radially inwardly spaced from the inner peripheral surface of the outer preform 12 and may contact the inner peripheral surface of the outer container X2 after blow molding.

[0029] In this embodiment, a second stepped portion (stepped portion) 19 facing upward and an inner rib (rib) 27 extending upward from the second stepped portion 19 are formed on the inner peripheral surface of the inner preform 11, and at least a part of the inner rib 27 is adjacent to the crystallization region 16 from above the crystallization region 16.

[0030] The inner rib 27 is spaced downward from the upper end of the inner mouth portion 21. Note that the inner rib 27 may be located at the upper end of the inner mouth portion 21. The upper end of the inner rib 27 is located at the same vertical position as the outside air introduction hole 13. Note that the upper end of the inner rib 27 may be located above or below the outside air introduction hole 13.

[0031] The lower end of the inner rib 27 is located in the crystallization region 16. The inner rib 27 and the second stepped portion 19 straddle the upper end of the crystallization region 16 in the vertical direction. The lower end of the inner rib 27 is provided over the entire vertical length in the crystallization region 16. Note that the inner rib 27 and the second stepped portion 19 may be spaced upward from the crystallization region 16. The upper and lower ends of the inner rib 27 decrease in radial size as they face outward in the vertical direction. The lower end of the inner rib 27 is continuously connected without a step to a portion of the inner peripheral surface of the inner preform 11 that is continuous with the crystallization region 16 from below the crystallization region 16. Note that the lower end of the inner rib 27 may be continuously connected to the inner peripheral surface of the inner preform 11 via a step.

[0032] Among the inner ribs 27, the radial size is the largest at the portion adjacent to the crystallization region 16 from above the crystallization region 16. Note that the radial size of the inner rib 27 may be the same or different over the entire vertical length. Among the inner ribs 27, the portion where the radial size is the largest is separated upward from the crystallization region 16 and is located at the lower edge of the inner mouth portion 21. Note that among the inner ribs 27, the portion where the radial size is the largest may be located above, below, or in the crystallization region 16 with respect to the lower edge of the inner mouth portion 21.

[0033] As shown in FIG. 2, the inner rib 27 is formed in a curved surface shape protruding inward in the radial direction in a cross-sectional view orthogonal to the vertical direction. In the cross-sectional view, the radius of curvature of the inner rib 27 is larger than the protruding amount of the inner rib 27 from the inner peripheral surface of the inner preform 11. The interval between adjacent inner ribs 27 in the circumferential direction is larger than the circumferential size of the inner rib 27. The inner ribs 27 are provided in an odd number at equal intervals in the circumferential direction. Note that the shape, arrangement position, etc. of the rib 27 may be changed as appropriate.

[0034] As described above, according to the preform 1 for double container molding according to the present embodiment, the inner rib 27 is formed on the inner peripheral surface of the inner preform 11, and at least a part of the inner rib 27 is adjacent to the crystallization region 16 from above the crystallization region 16. Therefore, in the inner preform 11, the rigidity of the portion (hereinafter, adjacent portion) continuous with the crystallization region 16 from above the crystallization region 16 is increased, and when the crystallization region 16 is provided, even if the inner preform 11 is heated, it is possible to suppress the adjacent portion from expanding outward in the radial direction, and it is possible to suppress the inner mouth portion 21 from being difficult to fit into the outer mouth portion 22. Since the inner rib 27 extends upward from the second step portion 19 facing upward, the preform 1 for double container molding having the inner rib 27 can be easily injection molded.

[0035] Since the inner rib 27 is spaced downward from the upper end of the inner mouth portion 21, when transporting the double-container forming preform 1 or the double container X in the factory, a jig can be inserted into the upper end of the inner mouth portion 21 and pressed against the inner peripheral surface of the upper end of the inner mouth portion 21.

[0036] Since the lower end of the inner rib 27 is located in the crystallization region 16, the inner rib 27 straddles at least the upper end of the crystallization region 16 in the vertical direction, and the rigidity of the adjacent portion can be surely increased.

[0037] Note that the technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0038] The outer rib 17 and the first step portion 18 may not be provided on the outer peripheral surface of the inner preform 11. The inner preform 11 and the outer preform 12 may be blow-molded separately to form the inner container X1 and the outer container X2 individually, and then the body portion of the inner container X1 may be compressed and deformed, and the inner mouth portion 21 may be fitted into the outer mouth portion 22 that does not deform before and after blow molding, while inserting the inner container X1 into the outer container X2.

[0039] In addition, within the scope not departing from the spirit of the present invention, it is possible to appropriately replace the components in the above-described embodiments with well-known components, and the above-described embodiments and the modified examples may be appropriately combined.

Explanation of Reference Numerals

[0040] 1 Double-container forming preform 11 Inner preform 12 Outer preform 13 Outer air introduction hole 16 Crystallization region 19 Second step portion (step portion) 21 Inner mouth portion (mouth portion of inner preform) 22 Outer mouth portion (mouth portion of outer preform) 27 Inner rib (rib) O Central axis X double container X1 inner container X2 outer container

Claims

1. A preform for forming a double container, comprising an inner container that decreases in volume and deforms as the content to be contained decreases, and an outer container in which the inner container is housed, and an outside air introduction hole for introducing outside air between the inner container and the outside air is provided as the content decreases. It includes a bottomed cylindrical inner preform for forming the inner container and a bottomed cylindrical outer preform for forming the outer container. The inner preform is inserted into the outer preform with the mouth portion of the inner preform fitted into the mouth portion of the outer preform. The mouth portion of the preform is composed of the mouth portion of the outer preform and the mouth portion of the inner preform, and the outside air introduction hole is provided in the mouth portion of the preform. The inner preform is formed of a crystalline resin. In the inner preform, at least a portion that is adjacent to the mouth portion from below the mouth portion and is located below the outside air introduction hole is provided with a crystallization region. The degree of crystallinity of the crystallization region is greater than the degree of crystallinity of the portion of the inner preform other than the crystallization region. On the inner peripheral surface of the inner preform, A step portion facing upward, And a rib extending upward from the step portion are formed. At least a part of the rib is adjacent to the crystallization region from above the crystallization region. A preform for forming a double container.

2. The rib is separated downward from the upper end portion of the mouth portion of the inner preform. The preform for forming a double container according to claim 1.

3. The lower end portion of the rib is located in the crystallization region. The preform for forming a double container according to claim 1 or 2.

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