Double container

Abstract

To provide a double-structured container allowed to reduce the remaining volume of a content received while suppressing poor forming.SOLUTION: A double-structured container comprises an inner container 12 that volume-reduction-deforms with a decrease of a content received and an outer container 11 in which the inner container is furnished and is disposed with a mouth 13, a body 16 and a bottom 14 in this order from above toward below along a bottle-axis O direction, comprising an ambient-air admission hole 17 that admits ambient air between the outer container and the inner container as the content decreases. The bottom includes a bottom-wall portion 22 comprising a tread portion 23 positioned in an outer peripheral edge, a topped-cylindrical depression portion 24 positioned radially inner than the tread portion and hollowed upward. In a peripheral wall portion 25 of the depression portion, a plurality of protruding portions 27 are provided, with spacing, protruding radially inward. The protruding portions extend radially inward through steps 26 as going upward.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, a double container has been known that includes an inner container that undergoes volume reduction and deformation as the contained contents decrease, and an outer container in which the inner container is placed, with a mouth, a body, and a bottom arranged in this order from top to bottom along the bottle axial direction, and an outside air introduction hole for introducing outside air between the outer container and the inner container as the contents decrease. This double container is formed by fitting an inner preform for forming the inner container into an outer preform for forming the outer container, and then blow molding the outer preform and the inner preform together in a cavity of a molding die. As an example of this type of double container, as shown in Patent Document 1 below, a configuration is known in which the bottom wall portion of the bottom portion has a grounding portion located on the outer peripheral edge and a topped cylindrical recessed portion located radially inward from the grounding portion and recessed upward, and the peripheral wall portion of the recessed portion extends radially inward via a step portion as it extends upward. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-171317 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional double container described above, the step portion extends continuously over the entire circumferential length, so that during blow molding, the flow resistance of the resin material flowing along the stepped portion of the inner surface of the cavity of the molding die that forms the step portion is increased, and there was a risk that the peripheral wall portion of the recessed portion would become excessively thick. In this case, molding defects such as sink marks on the bottom wall and excessively thin body portions may occur.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a double container that can reduce the remaining amount of contents contained therein while suppressing molding defects. [Means for solving the problem]

[0006] The present invention employs the following means to solve the above problems. That is, the double container of the present invention comprises an inner container that undergoes volume reduction deformation as the contained contents decrease, and an outer container in which the inner container is placed, and the mouth, body, and bottom are arranged in this order from top to bottom along the bottle axial direction, and an outside air introduction hole is provided for introducing outside air between the outer container and the inner container as the contents decrease, and the bottom wall of the bottom comprises a grounding portion located on the outer periphery and a topped cylindrical recessed portion located radially inward from the grounding portion and recessed upward, and a plurality of ridges protruding radially inward are provided at intervals in the circumferential direction on the peripheral wall of the recessed portion, and the ridges are Along the way, there is a step portion formed in a curved shape that is recessed toward the outside in the radial direction, and as it goes upward, it becomes It's extending.

[0007] In the present invention, the protrusions extend radially inward via steps as they extend upward, so that when the inner preform for forming the inner container is fitted into the outer preform for forming the outer container and the outer preform and the inner preform are blow molded together in the cavity of a molding die, the flow resistance of the resin material flowing along the stepped portion of the inner surface of the cavity that forms the steps is increased, and the thickness of the protrusions can be ensured. This ensures the rigidity of the protrusions in the inner container, and makes it possible to prevent the inner container from peeling off from the outer container at the protrusions when the inner container undergoes volumetric deformation as the content contained therein decreases. Since the step portion is provided only on the protruding portion, the peripheral wall portion of the depression portion is prevented from becoming excessively thick without being hindered in stretching during blow molding. This makes it possible to prevent molding defects such as sink marks in the bottom wall portion and excessive thinning of the body portion, and also makes it possible to increase the adhesive force between the inner container and the outer container at the peripheral wall portion of the depression portion, thereby preventing the inner container from peeling off from the outer container at the peripheral wall portion of the depression portion when the inner container undergoes volumetric deformation as the contained contents decrease. As a result, it is possible to reduce the volume of the inner container as designed as the amount of content stored decreases while minimizing molding defects, thereby reducing the amount of remaining content.

[0008] The upper and lower surfaces of the ceiling wall of the recess may be flat.

[0009] In this case, the upper and lower surfaces of the ceiling wall of the depression are flat, so that during blow molding, the resin material flows more smoothly with less snagging on the various parts of the inner surface of the cavity that form the depression and protrusions, improving shapeability and enabling the depression and protrusions to be molded with precision.

[0010] The step may be located radially inward from a peripheral wall portion of the recess.

[0011] In this case, the step portion of the protrusion is located radially inward from the peripheral wall portion of the depression, so that during the blow molding process as described above, it becomes possible to easily draw the resin material from the part of the inner cavity surface that molds the peripheral wall portion of the depression to the part that molds the protrusion, enabling the depression and the protrusion to be molded with precision. Effect of the Invention

[0012] According to this invention, it is possible to reduce the remaining amount of the contained contents while suppressing molding defects. [Brief description of the drawings]

[0013] [Figure 1] 1 is a side view including a partial vertical cross section of a double container shown as one embodiment of the present invention, as viewed from the outside in a radial direction. [Diagram 2] FIG. 2 is a bottom view of FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, a double container according to one embodiment will be described with reference to the drawings. 1, the double container 1 according to this embodiment includes an inner container 12 that undergoes volume reduction deformation as the contained contents decrease, and an outer container 11 in which the inner container 12 is housed. The outer surface of the inner container 12 is provided so as to be separable from the inner surface of the outer container 11. In the example shown in the figure, the inner container 12 is highly flexible and is laminated on the inner surface of the outer container 11 in a manner that allows it to be peeled off. In addition, a gap may be provided between the inner surface of the outer container 11, excluding the peripheral wall portion of the recessed portion described below, and the outer surface of the inner container 12, excluding the peripheral wall portion of the recessed portion described below.

[0015] The double container 1 is formed by integrally blow molding the outer preform and the inner preform in a state where the inner preform for forming the inner container 12 is fitted into the outer preform for forming the outer container 11. In other words, the double container 1 is a biaxially stretched blow container.

[0016] The inner container 12 and the outer container 11 are made of synthetic resin material, and may be made of 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).

[0017] The double container 1 has a mouth 13, a shoulder 15, a body 16, and a bottom 14. The mouth 13, the shoulder 15, the body 16, and the bottom 14 are arranged in this order coaxially with a common axis. Hereinafter, this common axis will be referred to as the bottle axis O, the side of the mouth 13 of the double container 1 along the bottle axis O will be referred to as the upper side, and the side of the bottom 14 of the double container 1 will be referred to as the lower side. When viewed from the direction of the bottle axis O, the direction intersecting the bottle axis O will be referred to as the radial direction, and the direction going around the bottle axis O will be referred to as the circumferential direction.

[0018] The mouth 13 of the double container 1 is formed by stacking the mouth of the inner container 12 and the mouth of the outer container 11, the shoulder 15 of the double container 1 is formed by stacking the shoulder of the inner container 12 and the shoulder of the outer container 11, the body 16 of the double container 1 is formed by stacking the body of the inner container 12 and the body of the outer container 11, and the bottom 14 of the double container 1 is formed by stacking the bottom of the inner container 12 and the bottom of the outer container 11. In the following description, unless otherwise specified, it is assumed that both the inner container 12 and the outer container 11 have the same shape.

[0019] The size of the double container 1 in the bottle axis O direction is, for example, 115 mm or more and 220 mm or less. The capacity of the double container 1 is, for example, 150 ml or more and 600 ml or less. In the illustrated example, the size of the double container 1 in the bottle axis O direction is about 180 mm, and the double container 1 is for a capacity of 330 ml. The mouth 13 of the double container 1 is formed in a cylindrical shape extending upward from the upper end of the shoulder portion 15 . A flange portion that protrudes radially outward and extends continuously over the entire circumferential length is formed at the upper end of the mouth of the inner container 12. The flange portion is placed on the upper opening edge of the mouth of the outer container 11.

[0020] A male threaded portion 18 to which a cap (not shown) is screwed, and a sealed protrusion 19 to which a peripheral wall portion of the cap (not shown) is fitted are formed from top to bottom on the outer peripheral surface of the mouth of the outer container 11. The sealed protrusion 19 protrudes radially outward from the mouth of the outer container 11 and extends continuously over the entire circumferential length. An airtight seal is formed between the outer peripheral surface of the sealed protrusion 19 and the inner peripheral surface of the peripheral wall portion of the cap (not shown). The cap may be fitted to the mouth of the outer container 11 by undercut fitting.

[0021] An outside air introduction hole 17 is formed at the mouth of the outer container 11 to introduce outside air between the outer container 11 and the inner container 12 as the content decreases. The outside air introduction hole 17 is located at the radially outermost part of the sealed protrusion 19, and is located above the sealing surface that extends continuously over the entire circumferential length. The position where the outside air introduction hole 17 is formed is not limited to the mouth of the outer container 11, but may be, for example, the body, shoulder, or bottom of the outer container 11 other than the mouth, or may be between the upper opening edge of the mouth of the outer container 11 and the underside of the flange portion of the mouth of the inner container 12, etc.

[0022] The shoulder portion 15 extends radially outward as it goes downward from the lower end of the mouth portion 13. A plurality of vertical partition grooves 15a are formed at intervals in the circumferential direction in the shoulder portion 15. The shoulder portion 15 is formed in a curved shape protruding radially outward. The bottom portion 14 is formed in a cylindrical shape with a bottom. The outer peripheral surface of the peripheral wall portion 14b of the bottom portion 14 extends straight in the direction of the bottle axis O. A circumferential groove 14a is formed in the outer peripheral surface of the peripheral wall portion 14b of the bottom portion 14, and extends continuously over the entire circumferential length.

[0023] The upper end 16a of the body 16 extends straight in the direction of the bottle axis O. The outer peripheral surfaces of the upper end 16a of the body 16 and the peripheral wall 14b of the bottom 14 form the maximum outer diameter portion of the double container 1. The outer diameter of this maximum outer diameter portion is, for example, 58 mm or more and 74 mm or less. In the illustrated example, the outer diameter of the maximum outer diameter portion of the double container 1 is approximately 66 mm.

[0024] The portion of the body 16 located below the upper end 16a forms a constricted portion 21 that extends radially inward from the outside to the inside along the direction of the bottle axis O. The size of the constricted portion 21 in the direction of the bottle axis O is more than half the size of the body 16 in the direction of the bottle axis O. The size of the constricted portion 21 in the direction of the bottle axis O is greater than the size of each of the mouth 13, shoulder 15, and bottom 14 in the direction of the bottle axis O.

[0025] The radial distance between deepest part 21b located radially innermost of constricted part 21 and the maximum outer diameter part of double container 1, i.e., the depth of constricted part 21, is, for example, 2% to 10% of the outer diameter of the maximum outer diameter part of double container 1. In the illustrated example, the depth of constricted part 21 is about 6.1% of the outer diameter of the maximum outer diameter part of double container 1. The outer diameter of upper end part 16a of body part 16 is larger than the outer diameter of the upper end part of constricted part 21, and upper end part 16a of body part 16 and constricted part 21 are connected to each other via step part 16d.

[0026] The constricted portion 21 is configured by a concave curved surface portion 16b that is recessed radially inward and a convex curved surface portion 16c that bulges radially outward, which are connected in this order from top to bottom without any steps. The size of the concave curved surface portion 16b in the direction of the bottle axis O is larger than the size of the convex curved surface portion 16c in the direction of the bottle axis O. The size of the concave curved surface portion 16b in the direction of the bottle axis O may be smaller than the size of the convex curved surface portion 16c in the direction of the bottle axis O.

[0027] In a vertical cross-sectional view along the bottle axis O, the difference between the radii of curvature R1 and R2 of the concave curved surface portion 16b and the convex curved surface portion 16c is 20% or less, preferably 10% or less, of the larger of the radii of curvature R1 and R2. In the illustrated example, in the vertical cross-sectional view, the radius of curvature R1 (about 110 mm) of the concave curved surface portion 16b is larger than the radius of curvature R2 (about 100 mm) of the convex curved surface portion 16c. In addition, in the vertical cross-sectional view, the radius of curvature R1 of the concave curved surface portion 16b may be smaller than the radius of curvature R2 of the convex curved surface portion 16c. In the vertical cross section, the concave curved surface portion 16b and the convex curved surface portion 16c each have a curvature radius R1, R2 that is, for example, not less than 80 mm and not more than 120 mm.

[0028] A vertical reinforcing groove 28 is formed in the convex curved surface portion 16c, extending in the direction of the bottle axis O. It is to be noted that the vertical reinforcing groove 28 does not necessarily have to be formed in the convex curved surface portion 16c. The vertical reinforcing groove 28 is located below the deepest part 21b of the neck portion 21. The lower end of the vertical reinforcing groove 28 is located at the lower end 21a of the neck portion 21. In the illustrated example, the vertical reinforcing groove 28 reaches the lower edge of the neck portion 21. The inner surface of the vertical reinforcing groove 28 has a concave curved shape in a cross section perpendicular to the bottle axis O. The depth of both ends of the vertical reinforcing groove 28 in the direction of the bottle axis O becomes shallower toward the outside in the direction of the bottle axis O. A plurality of vertical reinforcing grooves 28 are formed at intervals in the circumferential direction on the convex curved surface portion 16c.

[0029] At least the narrowed portion (body) of the outer container 11 is capable of being squeezed (elastically deformed), and the inner container 12 shrinks and deforms in accordance with the squeeze deformation of the outer container 11. The body 16, the shoulder 15, and the bottom 14 are connected without any steps in the direction of the bottle axis O. The outer container 11 may be formed so as not to be elastically deformable.

[0030] Here, the bottom wall portion 22 of the bottom 14 includes a grounding portion 23 located on the outer peripheral edge, a topped cylindrical recessed portion 24 located radially inward from the grounding portion 23 and recessed upward, and a connecting portion 22a connecting the grounding portion 23 and the recessed portion 24. The grounding portion 23, the recessed portion 24, and the connecting portion 22a are arranged coaxially with the bottle axis O. The connecting portion 22a is located above the grounding portion 23 and extends upward as it moves radially inward. Note that the bottom wall portion 22 does not necessarily have to have the connecting portion 22a.

[0031] The upper and lower surfaces of the top wall portion 29 of the recess 24 are flat surfaces facing in the bottle axis O direction. The peripheral wall portion 25 of the recessed portion 24 extends radially inward as it extends upward. The peripheral wall portion 25 of the recessed portion 24 is formed in a curved shape that protrudes radially outward. A plurality of ridges 27 protruding radially inward are provided on peripheral wall 25 of recess 24 at intervals in the circumferential direction.

[0032] 2, three or more odd number of protrusions 27 are provided at equal intervals in the circumferential direction. An even number of four or more protrusions 27 may be provided at equal intervals in the circumferential direction. The interval between adjacent protrusions 27 in the circumferential direction is equal to the size of the protrusions 27 in the circumferential direction. The circumferential size of the protrusion 27 decreases toward the top. As shown in Figures 3 and 4, the protrusion 27 is provided over the entire length of the peripheral wall 25 of the depression 24 in the direction of the bottle axis O. The upper edge of the protrusion 27 reaches the outer peripheral edge of the top wall 29 of the depression 24.

[0033] As shown in Figure 2, the protrusion portion 27 is defined by a radially facing top wall 31 and a pair of side walls 32 extending radially inward from the peripheral wall portion 25 of the recessed portion 24 and respectively connected to both circumferential ends of the top wall 31. The circumferential distance between the pair of side walls 32 becomes smaller toward the inside in the radial direction. In a cross-sectional view perpendicular to the bottle axis O, the side walls 32 and the peripheral wall portion 25 of the recess 24 are substantially perpendicular to each other.

[0034] In this embodiment, the protrusions 27 extend radially inwardly via the step portions 26 as they extend upward. 3 and 4, step portion 26 is formed in a curved shape recessed radially outward. Step portion 26 is located radially inward of peripheral wall portion 25 of recess 24.

[0035] In the vertical cross section, the length of upper portion 27a of protrusion portion 27 located above step portion 26 is shorter than the length of lower portion 27b located below step portion 26. Upper portion 27a and lower portion 27b are formed into a curved surface protruding radially inward. In the vertical cross section, the radius of curvature of lower portion 27b is smaller than the radius of curvature of upper portion 27a and larger than the radius of curvature of step portion 26. In the vertical cross section, lower portion 27b protrudes radially inward with respect to straight line L circumscribing upper portion 27a.

[0036] As described above, in the double container 1 of this embodiment, the protrusion 27 extends radially inward via the step 26 as it moves upward. Therefore, when the inner preform for forming the inner container 12 is fitted into the outer preform for forming the outer container 11 and the outer preform and the inner preform are blow molded together in the cavity of a molding die, the flow resistance of the resin material flowing along the stepped portion of the inner surface of the cavity that forms the step 26 is increased, and the thickness of the protrusion 27 can be ensured. This ensures the rigidity of the protrusion portion of the inner container 12, and when the inner container 12 undergoes volumetric deformation as the contained contents decrease, it is possible to prevent the inner container 12 from peeling off from the outer container 11 at the protrusion portion 27.

[0037] Since the step portion 26 is provided only on the protruding portion 27, the peripheral wall portion 25 of the depression portion 24 is prevented from becoming excessively thick without being hindered in stretching during blow molding. This makes it possible to prevent molding defects such as sink marks in the bottom wall portion 22 and excessive thinning of the body portion 16, and also makes it possible to increase the adhesive force between the inner container 12 and the outer container 11 at the peripheral wall portion 25 of the depression portion 24, thereby making it possible to prevent the inner container 12 from peeling off from the outer container 11 at the peripheral wall portion 25 of the depression portion 24 when the inner container 12 undergoes volumetric deformation as the contained contents decrease.

[0038] As a result, it is possible to reduce the volume of the inner container 12 as designed as the amount of content stored therein decreases while minimizing molding defects, and it is possible to reduce the amount of remaining content.

[0039] Since the upper and lower surfaces of top wall portion 29 of depressed portion 24 are flat, during blow molding, the resin material flows more smoothly with less snagging on the various parts of the inner surface of the cavity that form depressed portion 24 and protrusion portion 27, improving formability and enabling depressed portion 24 and protrusion portion 27 to be molded with precision.

[0040] Since the step portion 26 of the protrusion portion 27 is located radially inward from the peripheral wall portion 25 of the depressed portion 24, during the blow molding process as described above, it becomes possible to easily draw the resin material from the portion of the inner cavity surface that molds the peripheral wall portion 25 of the depressed portion 24 to the portion that molds the protrusion portion 27, and the depressed portion 24 and the protrusion portion 27 can be molded with precision.

[0041] 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.

[0042] The body portion 16 may not have a constricted portion 21 and may extend straight in the bottle axis O direction, for example. A plurality of step portions 26 may be provided at intervals in the bottle axis O direction. The step portion 26 may be continuous with the peripheral wall portion 25 of the recessed portion 24 in the circumferential direction.

[0043] In addition, within the scope of the invention, the components in the above-described embodiments may be replaced with well-known components, and the above-described embodiments and modified examples may be combined as appropriate. [Explanation of symbols]

[0044] 1 double container 11 Outer container 12 Inner container 13 Mouth 14 Bottom 16 Torso 17. Outside air intake 22 Bottom wall 23 Grounding part 24 Depression 25 Surrounding wall of the sunken area 26 Step section 27 Projection part 29 Ceiling wall of sunken area O Bottle stem

Claims

1. The bottle has an inner container that reduces in volume as the amount of content contained therein decreases, and an outer container in which the inner container is housed, and the bottle has a mouth, a body, and a bottom that are arranged in this order from top to bottom along the bottle axial direction; an outside air introduction hole for introducing outside air between the outer container and the inner container as the content decreases; The bottom wall of the bottom portion is A grounding portion located on an outer periphery; a cylindrical recessed portion having an upper end and recessed upward, the recessed portion being located radially inward from the grounding portion, A plurality of protrusions protruding radially inward are provided at intervals in the circumferential direction on a peripheral wall of the recessed portion, The protrusion portion extends radially inward as it extends upward, via a step portion formed in a curved surface shape that is recessed radially outward.

2. The double container according to claim 1 , wherein the upper and lower surfaces of the top wall of the recessed portion are flat.

3. The double container according to claim 1 or 2, wherein the step portion is located radially inward from the peripheral wall portion of the recessed portion.

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