JP7549205B2 - Double container - Google Patents

Description

The present invention relates to a double container.

Patent document 1 discloses a double container with a container body having an outer shell and an inner bag, in which the inner bag shrinks as the contents decrease.

JP 2015-101396 A

In containers such as that described in Patent Document 1, when the inner bag shrinks, the opposing inner surfaces of the inner bag may come close to each other, forming a constricted area in which the flow path through which the contents pass is narrowed. When a constricted area is formed, the dischargeability of the contents may be impaired.

The present invention was made in consideration of these circumstances, and provides a double-walled container that prevents the formation of a constriction in the inner bag when the inner bag shrinks.

According to the present invention, there is provided a double container having an outer shell and an inner bag, the inner bag being configured to shrink as the contents decrease, the container body having a storage section and a mouth section, the mouth section being arranged to extend from the upper end of the storage section, the storage section having, in order from the mouth section side, a shoulder section, a body section, and a bottom section, the body section being arranged between the shoulder section and the bottom section, the shoulder section being a portion that is visible when the container body is viewed from the mouth section side in a direction along the central axis of the mouth section, the shoulder section being provided with a pair of upper clamping sections arranged to sandwich the mouth section, and the outer shell clamping the inner bag at the upper clamping sections.

In the present invention, the inner bag is clamped by the outer shell at a pair of upper clamping parts provided on the shoulders, so that the opposing inner surfaces of the inner bag are less likely to come close to each other in the direction in which the upper clamping parts extend, and the formation of a narrowed portion is suppressed.

Various embodiments of the present invention will be described below. The embodiments described below can be combined with each other.
Preferably, in the above-described double container, no gap is provided between the outer shell and the inner bag in the upper clamping portion.
Preferably, in the above-described double container, the body portion is at least partially flattened.

1A shows a container body 3 of a double container 1 according to one embodiment of the present invention, with FIG. 1A being a plan view, FIG. 1B being a front view, and FIG. 1C being a bottom view. 2A is a cross-sectional view taken along the line AA in FIG. 1A, and FIG. 2B shows the state after the inner bag 14 has been separated from the outer shell 12 and shrunk from the state shown in FIG. 2A. 4A to 4C are cross-sectional views for explaining a manufacturing method of the container body 3. FIG. 3 shows the mold 31 and parison 33 as viewed from the plane BB (for convenience, only the outline of the parison 33 is shown by a dotted line). FIG. 4 is a front view showing the container body 3 of the double container 1 of the comparative example.

The following describes the embodiments of the present invention. The various features shown in the embodiments below can be combined with each other. In addition, each feature can be an invention independently.

As shown in FIG. 1, the double container 1 of one embodiment of the present invention includes a container body 3. The container body 3 includes a storage section 7 and a mouth section 9.

As shown in Figures 1 and 2, the container body 3 has an outer shell 12 and an inner bag 14 in the storage section 7 and the mouth section 9. As the contents decrease, the inner bag 14 separates from the outer shell 12 and shrinks. Before filling the contents, a preliminary peeling process may be performed to peel the inner bag 14 from the outer shell 12, and then the contents may be filled into the inner bag 14, or the inner bag 14 may be peeled from the outer shell 12 when the contents are discharged from the inner bag 14.

The outer shell 12 is formed thicker than the inner bag 14 so as to have high restorability. The outer shell 12 is made of, for example, polyolefins such as low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymers and mixtures thereof, or polyesters such as PET. The outer shell 12 may be made of multiple layers. It is preferable that the inner bag 14 is made of multiple layers. For example, an EVOH layer made of ethylene-vinyl alcohol copolymer (EVOH) resin can be used as the layer in contact with the outer layer, and an inner layer made of, for example, the polyolefin or polyester can be used as the layer in contact with the contents. It is preferable to use an adhesive layer between the EVOH layer and the inner layer.

The container body 3 can be formed by direct blow molding (blow molding using a molten cylindrical parison). In this case, the container body 3 can be formed by blow molding a molten cylindrical laminated parison 33 extruded from an extrusion head (not shown) using a pair of dies 31, 32, as shown in Figures 3 to 4. The parison 33 has a layer structure similar to that of the outer shell 12 and the inner bag 14. In one example, the parison 33 has, in order from the outer surface side, an outer layer 33a that becomes the outer shell 12 and an inner layer 33b that becomes the inner bag 14. The dies 31, 32 have cavity surfaces 31a, 32a, and the outer shape of the container body 3 is determined by the shape determined by the cavity surfaces 31a, 32a when the dies 31, 32 are closed. The cavity surfaces 31a and 32a include portions 31a1 and 32a1 that will become the storage section 7, portions 31a2 and 32a2 that will become the mouth section 9, and portions 31a3 and 32a3 that will become the bag section that is formed to be continuous with the mouth section 9 and cut after molding.

As shown in FIG. 1, the mouth 9 has an engagement portion 9d to which a mouth attachment member such as a cap or a pump can be attached. The engagement portion 9d is a male thread portion when the mouth attachment member is a screw type, and is an annular projection that protrudes in the circumferential direction when the mouth attachment member is a stopper type. The mouth 9 is provided to extend from the upper end of the storage portion 7. The mouth attachment member preferably has a check valve, which allows the contents to be discharged but prevents outside air from flowing into the container body 3. The mouth 9 is approximately cylindrical. The storage portion 7 has a circumscribed circle diameter larger than that of the mouth 9. All or most of the contents are stored in the storage portion 7, and the contents are discharged to the outside through the mouth 9 and the mouth attachment member.

The storage section 7 has, in order from the mouth 9 side, a shoulder section 21, a body section 22, and a bottom section 23. The body section 22 is provided between the shoulder section 21 and the bottom section 23. The shoulder section 21 is the portion visible when the container body 3 is viewed from the mouth 9 side in a direction along the central axis C of the mouth 9 (the portion visible in FIG. 1A excluding the mouth 9). The bottom section 23 is the portion visible when the container body 3 is viewed from the opposite side of the mouth 9 in a direction along the central axis C of the mouth 9 (the portion visible in FIG. 1C). The body section 22 is the portion of the storage section 7 other than the shoulder section 21 and the bottom 23.

The shoulder 21 is provided with a pair of upper clamping portions 24a, 24b (the letters a and b are omitted when no distinction is necessary) arranged to sandwich the mouth 9. As shown in FIG. 2, in the upper clamping portions 24, the outer shell 12 clamps the inner bag 14, so that the inner bag 14 cannot separate from the outer shell 12. In the comparative example container body in which the shoulder portion 21 is not provided with the upper clamping portion 24, as shown in FIG. 5, the inner surfaces of the inner bag 14 are close to each other, and the narrowed portion 25 is likely to form, narrowing the flow path through which the contents pass. However, in the container body 3 in which the shoulder portion 21 is provided with the upper clamping portions 24a and 24b as in this embodiment, the inner bag 14 is restricted by the upper clamping portions 24a and 24b as shown in FIGS. 1 and 2. Therefore, when the inner bag 14 contracts, the inner surfaces of the inner bag 14 are less likely to come close to each other in the direction in which the upper clamping portion 24 extends (the left-right direction in FIG. 1B), and as a result, the narrowed portion 25 is less likely to form. Since the contents (especially viscous contents such as mayonnaise and ketchup) are difficult to pass through the narrowed portion 25, when the narrowed portion 25 is formed, the dischargeability of the contents is likely to deteriorate. For this reason, in this embodiment, the formation of the narrowed portion 25 is suppressed to suppress the deterioration of the dischargeability of the contents.

The upper clamping portion 24 is preferably a pinch-off portion P1 formed by pinching the parison 33 between a pair of dies 31, 32 in direct blow molding, as shown in Figures 3 and 4. In general, in direct blow molding, blow molding is generally performed using a parison with an outer diameter smaller than the outer diameter of the mouth. In this case, the pinch-off portion is formed only at the portion where the cylindrical parison is closed at the bottom side and the mouth side of the container, but the pinch-off portion on the mouth side is usually cut off to form an opening. For this reason, as shown in Figure 5, the pinch-off portion P2 is provided only at the bottom 23 of the container body 3, and no pinch-off portion is provided at the shoulder 21. On the other hand, in this embodiment, in order to form the pinch-off portion P1 at the shoulder 21 and utilize it as the upper clamping portion 24, blow molding is performed using a parison 33 with an outer diameter larger than the outer diameter of the mouth 9, and the parison 33 is pinched between the dies 31, 32 at the portion that becomes the shoulder 21 to form the pinch-off portion P1. Furthermore, when a pinch-off portion P1 is formed on the shoulder portion 21, a pinch-off portion P1 is also formed on the side of the mouth portion 9 so as to continue from the shoulder portion 21. In this case, the upper clamping portion 24 is provided so as to straddle the shoulder portion 21 and the mouth portion 9. Furthermore, when the container body 3 is molded using such a parison 33 with a large outer diameter, the degree to which the parison 33 is stretched during molding (blow ratio) decreases, which has the advantage of reducing the degree of thickness unevenness of the container body 3.

Incidentally, the cross-sectional shape of the body 22 is not particularly limited, but it is preferable that at least a part of the body 22 is flat, and it is more preferable that the whole body 22 is flat. When the body 22 is flat, the blow ratio is likely to be large, so the technical significance of applying the present invention is particularly significant. Here, the flatness is defined by Equation 1. The maximum radius R1 and the minimum radius R2 are the distances from the central axis C to the outer surface of the container at the height position where the flatness is measured, where the distance from the central axis C is maximum and minimum, respectively, as shown in FIG. 1A.
(Formula 1) Flatness = Maximum radius R1/minimum radius R2 in a cross section perpendicular to the central axis C of the mouth portion 9

The flatness may be constant or may vary along the central axis C. The maximum flatness (flatness at the point where the flatness is maximum) is, for example, 1.2 to 6, and preferably 1.5 to 5. This value may be, for example, 1.2, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0, and may be within a range between any two of the numerical values exemplified here.

As shown in Figs. 1 and 3, if the outer diameter of the mouth portion 9 is D1 and the outer diameter of the parison 33 is D2, D2/D1 is, for example, 1.1 to 3, e.g., 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, 3.0, and may be within a range between any two of the numerical values exemplified here. Also, if the outer diameter of the part of the body portion 22 with the largest outer diameter is D3, it is preferable that D2 is smaller than D3. D2 is preferably D1+(D3-D1)×α, and α is preferably 0.1 to 0.9, e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and may be within a range between any two of the numerical values exemplified here.

Since the welding strength of the outer shell 12 is relatively low at the pinch-off portion, it is possible to form a gap between the outer shell 12 and the inner bag 14 by applying an impact to the pinch-off portion, and to use this gap as an outside air introduction portion for introducing outside air between the outer shell 12 and the inner bag 14. However, if a gap is formed between the outer shell 12 and the inner bag 14 at the upper clamping portion 24, the inner bag 14 may not be clamped by the outer shell 12 at the upper clamping portion 24. In this case, the formation of the narrowed portion 25 is not suppressed. For this reason, in this embodiment, no gap is provided between the outer shell 12 and the inner bag 14. In other words, at the upper clamping portion 24, as shown in FIG. 2A, the outer shells 12 on both sides sandwiching the upper clamping portion 24 are connected to each other, and the upper clamping portion 24 does not have air permeability, so that outside air cannot be introduced between the outer shell 12 and the inner bag 14 through the upper clamping portion 24. This allows the outer shell 12 to hold the inner bag 14 more securely in the upper clamping portion 24.

It is preferable that the portion of the shoulder 21 where the upper clamping portion 24 is provided has an angle of 70 to 90 degrees with respect to the central axis C of the mouth 9. This angle may be, for example, 70, 75, 80, 85, or 90 degrees, and may be within a range between any two of the numerical values exemplified here. By providing the upper clamping portion 24 at a portion that is nearly perpendicular to the central axis C in this manner, it is possible to more effectively prevent the inner surfaces of the inner bag 14 from coming close to each other in the direction in which the upper clamping portion 24 extends.

As described above, the bottom 23 is provided with a pinch-off portion P2 formed by pinching the parison 33 between the molds 31 and 32. Immediately after molding, the pinch-off portion P2 is the lower clamping portion 34 where the outer shell 12 clamps the inner bag 14. In this state, the inner bag 14 is restricted by the upper clamping portions 24a and 24b and the lower clamping portion 34, so that when the inner bag 14 contracts, the inner surfaces of the inner bag 14 are less likely to come close to each other in the direction in which the upper clamping portion 24 extends.

On the other hand, a gap may be formed between the outer shell 12 and the inner bag 14 by applying an impact to the pinch-off portion P2, and this gap may be used as an outside air inlet for introducing outside air between the outer shell 12 and the inner bag 14. In this case, the outside air inlet can be formed without perforating the outer shell 12. In this case, the inner bag 14 may not be clamped by the outer shell 12 at the pinch-off portion P2, in which case the inner bag 14 is restricted only by the upper clamping portions 24a and 24b. When the pinch-off portion P2 is used as the lower clamping portion 34, it is preferable to perforate the outer shell 12 at a portion other than the lower clamping portion 34 and the upper clamping portion 24 to form an outside air inlet hole.

1: Double container 3: Container body 7: Storage section 9: Mouth section 9d: Engagement section 12: Outer shell 14: Inner bag 21: Shoulder section 22: Body section 23: Bottom section 24: Upper clamping section 24a: Upper clamping section 24b: Upper clamping section 25: Narrowed section 31: Mold 31a: Cavity surface 31a1: Part 31a2: Part 31a3: Part 32: Mold 32a: Cavity surface 32a1: Part 32a2: Part 32a3: Part 33: Laminated parison 33a: Outer layer 33b: Inner layer 34: Lower clamping section C: Central axis P1: Pinch-off section P2: Pinch-off section

Claims (4)

A double container having a container body and a mouth attachment member,
The container body has an outer shell and an inner bag, and is configured so that the inner bag shrinks as the contents decrease, and includes a storage section and a mouth section;
The mouth portion includes an engagement portion and is provided so as to extend from an upper end of the storage portion,
The container has, in order from the mouth side, a shoulder portion, a body portion, and a bottom portion,
The body portion is disposed between the shoulder portion and the bottom portion,
the shoulder portion is a portion that is visible when the container body is viewed from the mouth side in a direction along the central axis of the mouth portion,
The shoulder portion is provided with a pair of upper clamping portions arranged to sandwich the mouth portion,
In the upper clamping portion, the outer shell clamps the inner bag,
The mouth attachment member has a check valve and is attached to the engagement portion of the mouth,
The contents are discharged to the outside through the mouth and the mouth attachment member,
A double container , wherein the upper pinch portion is a pinch-off portion formed in direct blow molding . The double container according to claim 1,
A double container, wherein the inner bag is not pinched by the outer shell at a pinch-off portion formed at the bottom. The double container according to claim 1 or 2,
A double container, in which no gap is provided between the outer shell and the inner bag in the upper clamping portion. The double container according to any one of claims 1 to 3,
The body portion has at least a portion having a flat shape.