Double container

Abstract

Even when the outside air introduction hole is provided, the mouth portion can be stably molded.SOLUTION: The inner vessel is disposed in the outer vessel in a state where the mouth portion 21 of the inner vessel is fitted into the mouth portion 22 of the outer vessel side X2, the mouth portion of the inner vessel is provided with the flange portion 25 protruding outward in the radial direction, continuously extending over the entire length in the circumferential direction, and disposed at the upper end opening edge 15 of the outer vessel, and the flange portion is provided with the outside air introduction hole 13 penetrating in the vertical direction, opening outward in the radial direction, and capable of communicating between the outer peripheral surface of the inner vessel and the inner peripheral surface of the outer vessel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a double container. [Background technology]

[0002] The double container comprises an inner container that shrinks and deforms as the contents stored therein decrease, and an outer container in which the inner container is placed, and is provided with an outside air inlet hole that introduces outside air between the inner container and the outer container as the contents decrease.The double container is configured such that the inner container is placed inside the outer container with the mouth of the inner container fitted into the mouth of the outer container. Known examples of this type of double container include a configuration in which an outside air inlet hole that is provided radially through the opening of the outer container and allows communication between the outer peripheral surface of the inner container and the inner peripheral surface of the outer container, as shown in Patent Document 1. The outside air inlet hole is molded, for example, using a molding pin during injection molding of the outer preform used to mold the outer container. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7200489 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in order to provide an air inlet hole that penetrates the opening of the outer container in the radial direction, the molten resin injected into the cavity for molding the outer preform needs to circulate around the outer peripheral surface of the molding pin. Therefore, the molten resin injected into the cavity has difficulty flowing around the outer peripheral surface of the molding pin, which can make it difficult to stably mold the area around the air inlet hole in the outer preform. For example, there is a risk that cracks may easily occur in the area, or the area may be molded with an irregular shape. If the outside air inlet hole is enlarged to make it easier to introduce outside air between the outer peripheral surface of the inner container and the inner peripheral surface of the outer container, it becomes more difficult to stably mold the peripheral portion.

[0005] The present invention provides a double-layered container whose opening can be stably formed even when an outside air inlet hole is provided. [Means for solving the problem]

[0006] A double container according to one aspect of the present invention comprises an inner container that reduces in volume as the contents contained therein decrease, and an outer container in which the inner container is placed, and the double container is provided with an outside air inlet hole that introduces outside air between the inner container and the outer container as the contents decrease, the inner container being placed within the outer container with the mouth of the inner container fitted into the mouth of the outer container, the mouth of the inner container being provided with a flange portion that protrudes radially outward, extends continuously over the entire circumferential length, and is located on the upper opening edge of the outer container, and the flange portion is provided with an outside air inlet hole that penetrates vertically, opens radially outward, and is capable of communicating between the outer peripheral surface of the inner container and the inner peripheral surface of the outer container.

[0007] The outside air inlet hole that can communicate between the outer peripheral surface of the inner container and the inner peripheral surface of the outer container is provided not in the mouth of the outer container but in the flange of the inner container, penetrating vertically and opening radially outward.Therefore, as in the case of providing an outside air inlet hole that penetrates radially through the mouth of the preform used to mold the outer container, there is no need to circulate the molten resin injected into the cavity that molds the preform so as to surround the outer surface side of the convex molding part that molds the outside air inlet hole; it is sufficient to simply allow it to flow in an up and down direction.This makes it possible to reduce the flow resistance of the molten resin flowing along the outer surface side of the convex molding part that molds the outside air inlet hole, and the mouth can be molded stably even when an outside air inlet hole is provided.

[0008] The outside air inlet hole may be provided from the flange portion to the mouth of the inner container, and the bottom surface of the inner surface of the outside air inlet hole facing radially outward may be located radially inward from the outer peripheral surface of the mouth of the inner container.

[0009] The outside air inlet hole is provided from the flange portion to the mouth of the inner container, and the bottom surface of the outside air inlet hole is located radially inward from the outer peripheral surface of the mouth of the inner container. Therefore, even if the mouth of the inner container is tightly fitted into the mouth of the outer container, outside air can be reliably introduced between the outer peripheral surface of the inner container and the inner peripheral surface of the outer container through the outside air inlet hole.

[0010] On the outer peripheral surface of the mouth of the inner container, a sealing protrusion extending circumferentially and in close contact with the inner peripheral surface of the mouth of the outer container is formed in a portion located below the outside air introduction hole, and an inclined recess is formed on the outer peripheral surface of the mouth of the inner container, recessed radially inward, dividing the sealing protrusion circumferentially and becoming shallower as it extends downward, and of the inner surface of the inclined recess, each side surface located at both circumferential ends extends in a direction separating from each other circumferentially as it extends downward, and the upper end of the inclined recess and the lower end of the outside air introduction hole may be connected in the vertical direction.

[0011] An inclined recess is formed on the outer surface of the mouth of the inner container, recessed radially inward and dividing the sealing protrusion circumferentially, and the upper end of the inclined recess and the lower end of the outside air inlet hole are connected in the vertical direction.Since the inner container is securely fixed inside the outer container by the sealing protrusion, outside air from the outside air inlet hole can be reliably introduced between the outer surface of the inner container and the inner surface of the outer container through the inclined recess. Since the inclined recess becomes shallower as it goes downward, when the inner preform for molding the inner container is injection molded, it is possible to prevent the flow resistance of the molten resin from increasing suddenly when the molten resin from the gate reaches the molding portion at the lower end of the inclined recess, and it is possible to reliably spread the molten resin throughout the entire cavity. The inner surfaces of the inclined recess, each of the side surfaces located at both circumferential ends, extend in a direction that moves away from each other circumferentially as they extend downward. Therefore, even though the inclined recess becomes shallower as it extends downward, it is possible to ensure the cross-sectional area of ​​the flow path for outside air in the inclined recess over the entire vertical length, and outside air from the outside air inlet hole can be reliably introduced between the outer surface of the inner container and the inner surface of the outer container through the inclined recess.

[0012] A rib protruding radially inward may be provided on the inner surface of the inner container at a portion located below the inclined recess, and at least a portion of the inclined recess and the rib may be located on the same straight line extending in the vertical direction.

[0013] A rib protruding radially inward is provided on the inner peripheral surface of the inner container in a portion located below the inclined recess, and at least a portion of the inclined recess and the rib are located on the same straight line extending in the vertical direction, so that when the inner preform is injection molded, the molten resin from the gate flows from the bottom to the top through the molding portion of the rib, where flow resistance is low, and the molding portion of the inclined recess, where flow resistance is high. This makes it possible to prevent the momentum of the molten resin from weakening before it reaches the molding portion of the inclined recess, where flow resistance is high, and ensures that the molten resin spreads throughout the entire cavity.

[0014] The outer container may be made of a crystalline resin, and the opening of the outer container may be thermally crystallized.

[0015] Since the mouth of the outer container is thermally crystallized, the heat resistance of the mouth of the outer container in the double container is increased, allowing the inner container to be filled with high-temperature contents. Since the external air introduction hole that allows communication between the outer peripheral surface of the inner container and the inner peripheral surface of the outer container is provided in the flange portion of the inner container, rather than in the mouth portion of the outer container, even if the crystallinity of the mouth portion of the outer preform used to mold the outer container is increased by heating, it is possible to prevent the mouth portion of the outer preform from being deformed, for example, into a distorted shape. [Effects of the Invention]

[0016] According to one aspect of the present invention, even if an outside air introduction hole is provided, the mouth portion can be stably formed. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a longitudinal sectional view of a preform for molding a double container shown as one embodiment. [Figure 2] 2 is a top view of the mouth of the preform for molding a double container (the mouth of the double container) of FIG. 1. FIG. [Figure 3] 2 is a front view of an outside air introduction hole and an inclined recess of the inner preform (inner container) of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, a preform for molding a double container according to one embodiment will be described with reference to the drawings. As shown in FIG. 1, the preform 1 for molding a double container is used to mold a double container X, which includes an inner container X1 that shrinks and deforms as the contents contained therein decrease, and an outer container X2 in which the inner container X1 is placed, and which is provided with an outside air inlet hole 13 that introduces outside air between the inner container X1 and the outer container X2 as the contents decrease. The double container X is formed by blowing compressed air into an inner preform 11 (described later) to blow mold a double container molding preform 1. In the double container X, the body of the inner container X1 is formed so as to be shrinkable and deformable as the contents decrease, and is provided so as to be separable from the inner surface of the outer container X2.

[0019] The double container molding preform 1 includes a cylindrical inner preform 11 with a bottom for molding the inner container X1, and a cylindrical outer preform 12 with a bottom for molding the outer container X2. The mouth portion (hereinafter referred to as the inner mouth portion) 21 of the inner preform 11 is fitted into the mouth portion (hereinafter referred to as the outer mouth portion) 22 of the outer preform 12, and 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.

[0020] The inner opening 21 and the outer opening 22 are portions that do not deform before or after blow molding, and in the double container X, as in the preform 1 for molding a double container, the inner opening 21 is fitted into the outer opening 22. Hereinafter, the mouths of the inner container X1 and the outer container X2 will be referred to as an inner mouth 21 and an outer mouth 22, respectively, just like the preform 1 for molding a double container.

[0021] The inner preform 11 and the outer preform 12 are arranged coaxially on a common axis. Hereinafter, this common axis will be referred to as the central axis O, the inner opening 21 side and the outer opening 22 side along the central axis O will be referred to as the upper side, the inner bottom 23 side and the outer bottom 24 side along the central axis O will be referred to as the lower side, and the direction along the central axis O will be referred to as the up-down direction. The direction that intersects with the central axis O when viewed from the up-down direction will be referred to as the radial direction, and the direction going around the central axis O when viewed from the up-down direction will be referred to as the circumferential direction.

[0022] The inner preform 11 and the outer preform 12 are formed by injection molding. The inner preform 11 and the outer preform 12 are made of synthetic resin material, and may be the same material or different materials. Examples of synthetic resin materials include PET (polyethylene terephthalate), PP (polypropylene), PE (polyethylene), nylon (polyamide), and EVOH (ethylene-vinyl alcohol copolymer). In the illustrated example, the inner preform 11 and the outer preform 12 are each made of PET.

[0023] The inner preform 11 (inner container X1) and the outer preform 12 (outer container X2) are made of a crystalline resin. However, the inner preform 11 (inner container X1) and the outer preform 12 (outer container X2) do not have to be made of a crystalline resin. Crystalline resins contain amorphous parts in which molecular chains are disordered and crystalline parts in which molecular chains are regularly arranged. The degree of crystallinity increases as the content of crystalline parts increases. The degree of crystallinity mainly depends on the cooling rate after heating. The degree of crystallinity can be measured, for example, by density analysis, X-ray diffraction analysis, differential scanning calorimetry, FT-IR analysis, or solid-state NMR analysis.

[0024] On the outer peripheral surface of the outer opening 22, there are formed, from top to bottom, a locking projection 22a into which a cap (not shown) is undercut-fitted, a sealed projection 22b into which the peripheral wall of the cap (not shown) is externally fitted, and a neck ring 22c. The cap may be screwed onto the outer opening 22.

[0025] The locking projection 22a, the sealed projection 22b, and the neck ring 22c project radially outward from the outer opening 22 and extend continuously over the entire circumferential length. An airtight seal is formed between the outer peripheral surface of the sealed projection 22b and the inner peripheral surface of the peripheral wall of the cap (not shown). The outer diameter of the neck ring 22c is larger than the outer diameters of the locking projection 22a and the sealed projection 22b. The neck ring 22c is located below the peripheral wall of the cap (not shown).

[0026] The outer opening portion 22 is a portion of the outer preform 12 that is located above and includes the same position in the up-down direction as the lower surface of the neck ring 22c. The crystallinity of the outer opening portion 22 of the outer preform 12 is higher than that of the other portions. In the outer preform 12, the outer opening portion 22 has a lower light transmittance than the other portions. In the outer preform 12, the outer opening portion 22 has a higher Young's modulus than the other portions. The outer opening portion 22 is a thermally crystallized region in which the crystallinity has been increased by heating. Note that the outer opening portion 22 does not have to be thermally crystallized.

[0027] The inner mouth portion 21 is the portion of the inner preform 11 that is fitted into the outer mouth portion 22. In other words, the inner mouth portion 21 is the portion of the inner preform 11 that includes the same position in the up-down direction as the lower surface of the neck ring 22c of the outer preform 12 and is located above it. The inner mouth portion 21 is provided with a flange portion 25 that protrudes radially outward, extends continuously over the entire circumferential length, and is located on the upper end opening edge 15 of the outer preform 12. The flange portion 25 is provided at the upper end portion of the inner mouth portion 21.

[0028] The aforementioned outside air introduction holes 13 are provided in the flange portion 25, penetrate the flange portion 25 in the up-down direction, and open radially outward. The outside air introduction holes 13 are formed to be able to communicate between the outer peripheral surface of the inner preform 11 and the inner peripheral surface of the outer preform 12. A plurality of outside air introduction holes 13 are provided at equal intervals in the circumferential direction. Note that the outside air introduction holes 13 may be provided with different intervals between adjacent outside air introduction holes 13 in the circumferential direction, or only one may be provided.

[0029] As shown in FIGS. 1 and 3 , the outside air introduction hole 13 is provided from the flange portion 25 to the inner opening 21. The outside air introduction hole 13 penetrates the flange portion 25 in the up-down direction, and the lower end of the outside air introduction hole 13 is located at the upper end of the inner opening 21. Of the inner surface of the outside air introduction hole 13, a bottom surface 13a facing radially outward is located radially inward from the outer circumferential surface of the inner opening 21. The bottom surface 13a of the outside air introduction hole 13 extends straight in the up-down direction. The bottom surface 13a of the outside air introduction hole 13 is provided over the entire up-down area of ​​the flange portion 25 and over the upper end of the inner opening 21. As shown in FIGS. 2 and 3 , of the inner surface of the outside air introduction hole 13, both side surfaces 13b facing in the circumferential direction extend in directions that move away from each other in the circumferential direction as they move radially outward.

[0030] A sealing protrusion 26 that extends circumferentially and comes into close contact with the inner peripheral surface of the outer opening 22 is formed on the outer peripheral surface of the inner opening 21 at a portion located below the outside air introduction hole 13. A plurality of sealing protrusions 26 are provided at intervals in the vertical direction. Note that there may be only one sealing protrusion 26, or none at all.

[0031] The outer peripheral surface of the inner opening 21 is formed with inclined recesses 14 that are recessed radially inward, divide the sealing protrusions 26 in the circumferential direction, and become shallower as they extend downward. The inclined recesses 14 divide the multiple sealing protrusions 26 in the circumferential direction. The upper end of the inclined recess 14 and the lower end of the outside air introduction hole 13 are vertically connected. In the illustrated example, the upper end of the inclined recess 14 and the lower end of the outside air introduction hole 13 are vertically connected. Note that the upper end of the inclined recess 14 may be spaced downward from the lower end of the outside air introduction hole 13. The upper end of the bottom surface 14b of the inner surface of the inclined recess 14, which faces radially outward, and the lower end of the bottom surface 13a of the outside air introduction hole 13 are vertically connected without a step. The circumferential centers of the upper end of the inclined recess 14 and the lower end of the outside air introduction hole 13 coincide with each other, and their circumferential sizes are the same. Of the inner surface of the inclined recess 14, the side surfaces 14a located at both ends in the circumferential direction extend in directions that move away from each other in the circumferential direction as they extend downward. The lower edge of the inclined recess 14 is continuous without any step with the outer circumferential surface of the inner opening 21. The lower edge of the inclined recess 14 has a downwardly projecting curved shape when viewed from the front radially outward.

[0032] A gate mark is provided in the radial center of the outer surface of the inner bottom 23 for supplying molten resin into the cavity of the mold that molds the inner preform 11. In the outer preform 12, a gate mark is provided in the radial center of the outer surface of the outer bottom 24. The positions of the gate marks may be changed as appropriate in each of the inner preform 11 and the outer preform 12. The gate marks are also visible in each of the inner container X1 and the outer container X2.

[0033] An inner rib (rib) 27 that protrudes radially inward is formed on the inner peripheral surface of the inner preform 11 in a portion located below the inclined recess 14. At least a portion of the inclined recess 14 and the inner rib 27 are positioned on the same straight line extending in the up-down direction. In the illustrated example, an upward-facing first step 19 is formed on the inner peripheral surface of the inner preform 11, and the inner rib 27 extends upward from the first step 19.

[0034] Here, in the inner preform 11, at least a portion adjacent to the inner mouth portion 21 from below the inner mouth portion 21 and located below the inclined recess 14 is provided with a crystallized region 16 having a higher degree of crystallinity than other portions.

[0035] In the inner preform 11, the crystallized region 16 has a lower light transmittance than the other portions. In the inner preform 11, the crystallized region 16 has a higher Young's modulus than the other portions. The crystallized region 16 is a thermally crystallized region in which the degree of crystallization has been increased by heating. The crystallized region 16 extends continuously over the entire circumferential length. The crystallized region 16 is spaced downward from the inner opening 21. The crystallization region 16 may be provided in the inner opening 21, for example.

[0036] In the inner preform 11, a portion including the same position in the vertical direction as the upper edge of the crystallized region 16 and positioned above it serves as a non-stretched region 28 that is not stretched during blow molding. The crystallization region 16 may be provided in the non-stretched region 28, or may be provided across the non-stretched region 28 and a stretched region located below the non-stretched region 28.

[0037] In the illustrated example, an outer rib 17 protruding radially outward is provided on the outer peripheral surface of the crystallization region 16. The outer rib 17 ensures an air passage extending vertically 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 of the outer rib 17 is located above the crystallization region 16 and below the inclined recess 14, and the lower end of the outer rib 17 is located below the crystallization region 16. The outer rib 17 abuts against the inner peripheral surface of the outer preform 12. A plurality of outer ribs 17 are provided at intervals in the circumferential direction.

[0038] A downward-facing second step 18 is formed on the outer circumferential surface of the inner preform 11. The second step 18 is located in the crystallization region 16. The second step 18 extends upward as it moves radially outward. The outer rib 17 may be spaced radially inward from the inner peripheral surface of the outer preform 12, or may be provided in the crystallization region 16 over the entire vertical length, or may be provided at a position spaced vertically from the crystallization region 16, or may be spaced radially inward from the inner peripheral surface of the outer preform 12 and abut against the inner peripheral surface of the outer container X2 after blow molding.

[0039] At least a portion of the inner rib 27 is adjacent to the crystallization region 16 from above the crystallization region 16 . The inner rib 27 is spaced downward from the upper end of the inner opening 21. The inner rib 27 may alternatively be located at the upper end of the inner opening 21.

[0040] The lower end of the inner rib 27 is located in the crystallization region 16. The inner rib 27 and the first step 19 straddle the upper end of the crystallization region 16 in the vertical direction. The lower end of the inner rib 27 is provided at the upper end of the crystallization region 16. Note that the inner rib 27 and the first step 19 may be spaced apart upward from the crystallization region 16. The outer peripheral edge of the inner rib 27 decreases in radial size with increasing distance from the center of the inner rib 27, and is connected without a step to the inner peripheral surface of the inner preform 11. Note that the outer peripheral edge of the inner rib 27 may be connected to the inner peripheral surface of the inner preform 11 via a step.

[0041] The inner ribs 27 have a curved shape that protrudes radially inward in a cross-sectional view perpendicular to the up-down direction. In the cross-sectional view, the radius of curvature of the inner ribs 27 is greater than the amount by which the inner ribs 27 protrude from the inner peripheral surface of the inner preform 11. The distance between adjacent inner ribs 27 in the circumferential direction is smaller than the circumferential size of the inner ribs 27. An odd number of inner ribs 27 are provided at equal intervals in the circumferential direction. The shape and location of the rib 27 may be changed as appropriate.

[0042] As described above, in the double container X of this embodiment, the outside air introduction hole 13 that can communicate between the outer peripheral surface of the inner container X1 and the inner peripheral surface of the outer container X2 is provided not in the outer opening 22 but in the flange 25 of the inner container X1, penetrating vertically and opening radially outward. Therefore, unlike when an outside air introduction hole 13 that penetrates radially through the opening of the preform for molding the outer container X2 is provided, the molten resin injected into the cavity for molding the preform does not need to be made to circulate around the outer surface side of the convex molding part that forms the outside air introduction hole 13; it is sufficient to simply make the molten resin flow in the vertical direction. This makes it possible to reduce the flow resistance of the molten resin flowing along the outer surface side of the convex molding part that forms the outside air introduction hole 13, and the inner opening 21 can be stably molded even when the outside air introduction hole 13 is provided.

[0043] The outside air introduction hole 13 is provided from the flange portion 25 to the inner opening portion 21, and the bottom surface 13a of the outside air introduction hole 13 is located radially inward from the outer peripheral surface of the inner opening portion 21. Therefore, even if the inner opening portion 21 is tightly fitted into the outer opening portion 22, outside air can be reliably introduced between the outer peripheral surface of the inner container X1 and the inner peripheral surface of the outer container X2 through the outside air introduction hole 13.

[0044] An inclined recess 14 is formed on the outer peripheral surface of the inner opening 21, recessed radially inward and dividing the sealing protrusion 26 circumferentially, and the upper end of the inclined recess 14 and the lower end of the outside air introduction hole 13 are connected in the vertical direction. Therefore, the inner container X1 is securely fixed inside the outer container X2 by the sealing protrusion 26, and outside air from the outside air introduction hole 13 can be securely introduced through the inclined recess 14 into the space between the outer peripheral surface of the inner container X1 and the inner peripheral surface of the outer container X2.

[0045] Since the inclined recess 14 becomes shallower as it goes downward, when the molten resin from the gate reaches the molding portion at the lower end of the inclined recess 14 during injection molding of the inner preform 11, it is possible to prevent a sudden increase in flow resistance of the molten resin, and the molten resin can be reliably distributed throughout the entire area of ​​the cavity.

[0046] Of the inner surface of the inclined recess 14, the side surfaces 14a located at both circumferential ends extend in a direction that separates them circumferentially as they extend downward. Therefore, even though the inclined recess 14 becomes shallower as it extends downward, it is possible to ensure the cross-sectional area of ​​the flow path for outside air in the inclined recess 14 over the entire vertical length, and outside air from the outside air inlet hole 13 can be reliably introduced between the outer surface of the inner container X1 and the inner surface of the outer container X2 through the inclined recess 14.

[0047] An inner rib 27 protruding radially inward is provided on the inner peripheral surface of the inner container X1 in a portion located below the inclined recess 14, and at least a portion of the inclined recess 14 and the inner rib 27 are located on the same straight line extending in the vertical direction, so that when the inner preform 11 is injection molded, the molten resin from the gate flows from bottom to top through the molding portion of the inner rib 27, where flow resistance is low, and the molding portion of the inclined recess 14, where flow resistance is high. This makes it possible to prevent the momentum of the molten resin from weakening before it reaches the molding portion of the inclined recess 14, where flow resistance is high, and ensures that the molten resin spreads throughout the entire cavity.

[0048] In the inner preform 11, at least the portion adjacent to the inner mouth portion 21 from below and located below the inclined recess 14 has a crystallized region 16 with a higher degree of crystallinity than other portions. Therefore, when compressed air is blown into the inner preform 11 and blow-molded to form the double container X, the crystallized region 16 is less likely to expand radially outward, making it easier to ensure an airway extending vertically between the inner container X1 and the outer container X2 in the portion located below the inclined recess 14.

[0049] Since at least a portion of the inner rib 27 is adjacent to the crystallization region 16 from above the crystallization region 16, the rigidity of the portion of the inner preform 11 that continues from above the crystallization region 16 (hereinafter referred to as the adjacent portion) is increased, and when the crystallization region 16 is provided, even if the inner preform 11 is heated, it is possible to prevent the adjacent portion from expanding radially outward, thereby preventing the inner opening portion 21 from becoming difficult to fit into the outer opening portion 22.

[0050] Since the outer opening 22 is thermally crystallized, the heat resistance of the outer opening 22 is increased in the double container X, and the inner container X1 can be filled (hot-filled) with high-temperature contents. Furthermore, in this case, even if the portion of the inner opening 21 that fits with the outer opening 22 is not thermally crystallized, the expansion of the inner opening 21 due to hot filling is suppressed by the thermally crystallized outer opening 22, and irregular deformation of the entire opening of the double container X can be suppressed.

[0051] The outside air introduction hole 13, which allows communication between the outer peripheral surface of the inner container X1 and the inner peripheral surface of the outer container X2, is provided in the flange portion 25 of the inner container X1, not in the outer opening portion 22. Therefore, even if the crystallinity of the outer opening portion 22 is increased by heating, it is possible to prevent the outer opening portion 22 from being deformed, for example, into a distorted shape.

[0052] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0053] The inner preform 11 may not be provided with the crystallized region 16, and the preform 1 for molding a double container may have a region in which the degree of crystallinity is increased by heating only in the outer opening portion 22. 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 of the inner container X1 may be compressed and deformed, and the inner container X1 may be inserted into the outer container X2 while the inner opening 21, which does not deform before or after blow molding, is fitted into the outer opening 22, which does not deform before or after blow molding, to form the double container X.

[0054] The outside air introduction hole 13 may be provided only in the flange portion 25 and not on the outer peripheral surface of the inner opening portion 21 . The bottom surface 13a of the outside air introduction hole 13 may be connected to the outer peripheral surface of the inner opening portion 21 without any step. The inclined recess 14 and the sealing protrusion 26 do not necessarily have to be formed on the outer peripheral surface of the inner opening portion 21 . The inner preform 11 does not necessarily need to have the inner rib 27, the first step portion 19, the outer rib 17, and the second step portion 18 formed thereon. The inner preform 11 does not necessarily need to be provided with the crystallization region 16 .

[0055] In addition, within the scope of the spirit of the present invention, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, and the above-described embodiments and the above-described variations may be combined as appropriate.

[0056] The aspects of the present invention are as follows, for example. <1> A double container comprising an inner container that reduces in volume as the contents contained therein decrease, and an outer container in which the inner container is placed, and an outside air inlet hole that introduces outside air between the inner container and the outer container as the contents decrease, The inner container is placed in the outer container with the mouth of the inner container fitted into the mouth of the outer container, a flange portion that protrudes radially outward from the mouth of the inner container, extends continuously over the entire circumferential length, and is located on the upper opening edge of the outer container; The flange portion has an outside air introduction hole that penetrates vertically and opens radially outward, allowing communication between the outer peripheral surface of the inner container and the inner peripheral surface of the outer container. <2> the outside air introduction hole is provided from the flange portion to the mouth portion of the inner container, a bottom surface of the inner surface of the outside air introduction hole facing outward in the radial direction is located radially inward from an outer peripheral surface of the mouth of the inner container; <1> The double container described in . <3> a sealing protrusion extending in a circumferential direction and in close contact with an inner circumferential surface of the mouth of the outer container is formed on an outer circumferential surface of the mouth of the inner container at a portion located below the outside air introduction hole; an inclined recess portion that is recessed radially inward on the outer peripheral surface of the mouth of the inner container, divides the sealing protrusion in the circumferential direction, and becomes shallower as it extends downward; The inner surfaces of the inclined recessed portion have side surfaces located at both ends in the circumferential direction that extend in directions that move away from each other in the circumferential direction as they extend downward, an upper end of the inclined recess and a lower end of the outside air introduction hole are in communication with each other in the vertical direction; <1> or <2> The double container described in . <4> a rib protruding radially inward is provided on the inner circumferential surface of the mouth of the inner container at a portion located below the inclined recess, At least a portion of the inclined recess and at least a portion of the rib are positioned on the same straight line extending in the up-down direction. <3> The double container described in . <5> The outer container is made of a crystalline resin, and the mouth of the outer container is thermally crystallized. <1> from <4> 1. A double container according to any one of the preceding items. [Explanation of symbols]

[0057] 1. Double container molding preform 11 Inner preform 12 Outer preform 13 Outside air intake 13a Bottom 14 Inclined recess 14a Side 15 Upper opening edge 16 Crystallization region 21 Inner opening (mouth of inner container) 22 Outer opening (outer container opening) 25 flange 26 Seal protrusion 27 Inner rib (rib) O center axis X double container X1 Inner container X2 outer container

Claims

1. A double container comprising an inner container that reduces in volume as the contents contained therein decrease, and an outer container in which the inner container is placed, and an outside air inlet hole that introduces outside air between the inner container and the outer container as the contents decrease, The inner container is placed in the outer container with the mouth of the inner container fitted into the mouth of the outer container, a flange portion that protrudes radially outward from the mouth of the inner container, extends continuously over the entire circumferential length, and is located on the upper opening edge of the outer container; The flange portion has an outside air introduction hole that penetrates vertically and opens radially outward, allowing communication between the outer peripheral surface of the inner container and the inner peripheral surface of the outer container.

2. the outside air introduction hole is provided from the flange portion to the mouth portion of the inner container, 2. The double container according to claim 1, wherein a bottom surface of the inner surface of the outside air introduction hole facing radially outward is located radially inward of an outer peripheral surface of the mouth of the inner container.

3. a sealing protrusion extending in a circumferential direction and in close contact with an inner circumferential surface of the mouth of the outer container is formed on an outer circumferential surface of the mouth of the inner container at a portion located below the outside air inlet; an inclined recess portion that is recessed radially inward on the outer peripheral surface of the mouth of the inner container, divides the sealing protrusion in the circumferential direction, and becomes shallower as it extends downward; The inner surfaces of the inclined recessed portion have side surfaces located at both ends in the circumferential direction that extend in directions that move away from each other in the circumferential direction as they extend downward, The double container according to claim 1 , wherein an upper end of the inclined recess and a lower end of the outside air introduction hole are vertically connected to each other.

4. a rib protruding radially inward is provided on the inner circumferential surface of the inner container at a portion located below the inclined recess, The double container according to claim 3 , wherein at least a portion of the inclined recess and at least a portion of the rib are positioned on the same straight line extending in the vertical direction.

5. 5. The double container according to claim 1, wherein the outer container is made of a crystalline resin, and the opening of the outer container is thermally crystallized.

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