JP7545019B2 - Storage container and manufacturing method thereof - Google Patents

Description

The present invention relates to a storage container capable of storing contents.

Conventionally, there is known a peelable laminate container that prevents air from entering the container due to the inner bag shrinking as the contents decrease (for example, Patent Document 1).

JP 2015-163531 A

The peelable laminate container in Patent Document 1 is constructed by covering the outer surface of a container formed by blow molding with a shrink film, but there are cases where an appearance that exudes a more luxurious feel is required.

The present invention was made in consideration of these circumstances, and aims to provide a storage container with excellent appearance.

According to the present invention, there is provided a storage container comprising a container body having an outer jacket integrally molded to cover the outer peripheral surface of the inner container, the outer jacket being an injection molded body, the inner container having an outermost layer and an adjacent layer adjacent to the outermost layer, and the melting point of the outermost layer resin constituting the outermost layer being lower than the melting point of the adjacent layer resin constituting the adjacent layer.

The storage container of the present invention has an excellent appearance because the outer jacket made of an injection molded body is integrally molded on the outer peripheral surface of the inner container. In addition, because the melting point of the outermost layer resin is lower than that of the adjacent layer resin, the thermal energy of the molten resin used to injection mold the jacket is not easily transferred to the inner container, suppressing deformation of the inner container. Furthermore, because the melting point of the outermost layer resin is lower than that of the adjacent layer resin, the adhesion between the jacket and the outermost layer is improved, and peeling of the adhesive surface of the jacket from the outer peripheral surface of the inner container due to impact such as dropping 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 storage container, the difference in melting point between the outermost layer resin and the adjacent layer resin is 5° C. or more.
Preferably, in the storage container described above, the thickness of the outermost layer relative to the thickness of the inner container is 10% or more.
Preferably, in the above-described storage container, the outermost layer resin contains an unmodified polyolefin.
Preferably, in the above-described storage container, the outermost layer resin contains an acid-modified polyolefin and the unmodified polyolefin.
Preferably, in the above-described storage container, the resin constituting the outer jacket has the same monomer units as the outermost layer resin.
Preferably, in the storage container described above, the inner container has an outer shell and an inner bag and is configured so that the inner bag shrinks as the contents decrease, and the outermost layer and the adjacent layer are provided on the outer shell.
Preferably, the method for manufacturing a storage container includes an integral molding step of integrally molding an inner container and an outer jacket, in which the integral molding step includes filling the space outside the inner container in a cavity of a mold with resin while placing the outer peripheral surface of the inner container within the mold to form the outer jacket, the inner container includes an outermost layer and an adjacent layer adjacent to the outermost layer, and the melting point of the outermost layer resin constituting the outermost layer is lower than the melting point of the adjacent layer resin constituting the adjacent layer.
Preferably, in the above-described method, the inside of the inner container is pressurized during the integral molding step.
Preferably, in the method described above, in the integral molding process, the resin is filled in a state in which the inner surface of the bottom surface of the inner container is pressed by a support rod inserted into the inner container.

FIG. 1 is a perspective view of a storage container 1 according to a first embodiment. FIG. FIG. 2 is a cross-sectional view of the container body 2. This shows the layer structure of the container body 2 in the region A in FIG. FIG. FIG. FIG. 11 is a cross-sectional view for explaining an integral molding process. FIG. 8 is an enlarged view of region B in FIG. 7 . 9A and 9B are perspective views of the storage container 1 of the second embodiment as viewed from different directions. FIG. 9B is a cross-sectional view of the container body 2 of FIG. 9A. This shows the layer structure of the container body 2 in the region C in FIG. 11 is a cross-sectional view of only the inner container 4 in FIG. 10. FIG. FIG. 7 is an enlarged view of the vicinity of the mouth 8 in FIG. 5 , showing a state in which an outside air introduction section 15 is provided at the mouth 8 of the inner container 4 in the third embodiment.

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.

1. First embodiment As shown in Fig. 1, a storage container 1 according to a first embodiment of the present invention includes a container body 2 and an opening member 3 such as a flat cap. The opening member 3 may be a pump or a hinge cap. As shown in Fig. 3, the container body 2 includes an inner container 4 and an outer jacket 5 integrated therewith. Each component will be described below.

<Inner container 4>
The inner container 4 shown in Figs. 5 and 6 is a container formed by any manufacturing method, and is preferably a blow-molded container formed by blow molding of a parison. The blow molding may be direct blow molding or injection blow molding. In direct blow molding, a container is manufactured by sandwiching a molten parison extruded from an extruder between a pair of split dies and blowing air into the parison. The parison may be cylindrical or sheet-shaped. In injection blow molding, a test tube-shaped parison with a bottom, called a preform, is formed by injection molding, and a container is manufactured by blow molding using this parison.

Since it is not easy to manufacture injection-molded containers with a multi-layer structure, it is particularly significant to apply the present invention to the inner container 4, which has a multi-layer structure. When forming an inner container 4 with a multi-layer structure, the parison also has a multi-layer structure. A parison with a multi-layer structure (multi-layer parison) can be formed by co-extrusion molding.

The inner container 4 is a cylindrical container with a bottom, and has a storage section 7 for storing the contents, and a mouth section 8 for discharging the contents from the storage section 7. The storage section 7 has a body section 7a and a bottom section 7b. The mouth section 8 is provided with an engagement section (male thread section) 8a, so that the opening member 3 can be attached.

When the inner container 4 is formed by direct blow molding, the inner container 4 has a cutout 7c (shown in FIG. 6) formed by crushing the parison with a pair of split dies. The cutout 7c is provided on the bottom 7b of the inner container 4, and the bottom of the inner container 4 is closed by welding the opposing surfaces of the parison to the cutout 7c. The shape of the storage section 7 can be various, such as a cylinder, a polygonal column, a polygonal pyramid, or a sphere.

As shown in FIG. 4, the inner container 4 comprises, in order from the outside of the inner container 4, an outermost layer 4c1, an adjacent layer 4c2, and another layer 4c3. Examples of constituent materials of the inner container 4 include unmodified polyolefin, acid-modified polyolefin, and EVOH. Examples of polyolefin include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, and mixtures thereof.

The melting point of the outermost layer resin constituting the outermost layer 4c1 is lower than the melting point of the adjacent layer resin constituting the adjacent layer 4c2. There is a risk that the inner container 4 will soften and deform due to the thermal energy of the molten resin when the outer jacket 5 is injection molded, but if the melting point of the outermost layer resin is lower than the melting point of the adjacent layer resin, the outermost layer resin will be melted by the thermal energy of the molten resin, and the outermost layer resin will absorb the thermal energy at this time, so the thermal energy transmitted to the inner container 4 will be reduced and deformation of the inner container 4 due to the injection pressure will be suppressed. In addition, since the outermost layer 4c1 is easily melted, the adhesiveness between the outer jacket 5 and the outermost layer 4c1 is improved, and peeling of the adhesive surface of the outer jacket 5 from the outer peripheral surface of the inner container 4 due to impact such as dropping is suppressed. In this specification, "melting point" means the melting peak temperature Tpm measured in accordance with JIS K 7121:2012.

The difference between the melting point of the outermost layer resin and the melting point of the adjacent layer resin is preferably 5°C or more, more preferably 10°C or more, and even more preferably 20°C or more. In this case, the above-mentioned deformation suppression and adhesion improvement effects are significant. This melting point difference is, for example, 5 to 50°C, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50°C, and may be within a range between any two of the numerical values exemplified here.

The melting point of the outermost layer resin is, for example, 90 to 130°C, and preferably 100 to 120°C. Specific examples of this melting point include 90, 95, 100, 105, 110, 115, 120, 125, and 130°C, and may be within a range between any two of the values exemplified here.

The thickness of the outermost layer 4c1 relative to the thickness of the inner container 4 is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more. In this case, the above-mentioned effects of suppressing deformation and improving adhesion are significant. The thickness of the outermost layer 4c1 relative to the thickness of the inner container 4 is, for example, 10 to 50%, specifically, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50%, and may be within a range between any two of the numerical values exemplified here.

The outermost layer resin preferably contains a polyolefin. The polyolefin may be an unmodified polyolefin or a modified polyolefin (e.g., an acid-modified polyolefin).

It is preferable that the outermost layer resin contains an unmodified polyolefin. If the outermost layer resin is composed only of modified polyolefin, the outermost layer 4c1 may become sticky and the inner container 4 may become difficult to handle. As the unmodified polyolefin, polyethylene is preferable, and one containing one or both of LDPE and LLDPE is more preferable. In this case, the melting point of the outermost layer resin tends to be low.

The outermost layer resin may contain an acid-modified polyolefin and an unmodified polyolefin. Since acid-modified polyolefin has excellent adhesive properties, by incorporating acid-modified polyolefin and unmodified polyolefin in the outermost layer resin, it is possible to improve the adhesiveness between the outer jacket 5 and the inner container 4 while suppressing excessive stickiness. The proportion of acid-modified polyolefin in the outermost layer resin is, for example, 5 to 95 mass%, and preferably 30 to 70 mass%. This proportion is specifically, for example, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 95 mass%, and may be within a range between any two of the numerical values exemplified here.

The adjacent layer 4c2 is a layer adjacent to the outermost layer 4c1. The adjacent layer resin constituting the adjacent layer 4c2 can be any resin with a higher melting point than the outermost layer resin. For example, if the outermost layer resin is LDPE, the adjacent layer resin can be HDPE or PP, which have a higher melting point than LDPE. In addition, the adjacent layer resin can be a recycled resin obtained by recycling burrs generated in a previous cycle. If the melting point of the resin constituting any of the layers constituting the inner container 4 is higher than that of the outermost layer 4c1, the melting point of the recycled resin will usually be higher than that of the outermost layer resin.

The thickness of the adjacent layer 4c2 relative to the thickness of the inner container 4 is, for example, 5 to 70%, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70%, and may be within a range between any two of the numerical values exemplified here.

The other layer 4c3 is a layer that is present on the inner side of the inner container 4 relative to the adjacent layer 4c2. The other layer 4c3 is preferably made of a resin with excellent heat resistance and rigidity, such as polypropylene. The other layer 4c3 can be omitted if not required. The thickness of the adjacent layer 4c2 relative to the thickness of the inner container 4 is preferably 20% or more. In this case, the other layer 4c3 makes it easier to increase the heat resistance and rigidity of the inner container 4. The thickness of the adjacent layer 4c2 relative to the thickness of the inner container 4 is, for example, 0 to 70%, and more specifically, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70%, and may be within a range between any two of the numerical values exemplified here.

The inner container 4 is, for example, a multi-layer container of five types and six layers, and specific examples of the layer configuration are as follows: The adhesive layer is a layer made of an adhesive resin such as acid-modified polypropylene.

Furthermore, the adjacent layer 4c2 may be a recycled resin layer, as shown in Table 2. The recycled resin includes various resins constituting the outermost layer 4c1 and the other layer 4c3, and since the melting point of the resin constituting the other layer 4c3 is higher than the melting point of the outermost layer resin, the melting point of the recycled resin is also higher than the melting point of the outermost layer resin.

＜Coat 5＞
2 and 3, the mantle 5 is an injection molded body that is integrally molded so as to cover the outer peripheral surface 4a (preferably the outer peripheral surface 4a and the bottom surface 4b) of the inner container 4. The mantle 5 includes a cylindrical portion 5a and a bottom portion 5b. The cylindrical portion 5a and the bottom portion 5b cover the outer peripheral surface 4a and the bottom surface 4b, respectively. The mantle 5 covers at least the storage portion 7, and may or may not cover the mouth portion 8.

It is preferable that the resin constituting the outer jacket 5 has the same monomer units as the outermost layer resin constituting the outermost layer 4c1. In this case, peeling of the adhesive surface between the outer jacket 5 and the outer peripheral surface 4a is suppressed when the container is dropped. For example, polyethylene can be used for the outermost layer 4c1 of the inner container 4, and an ionomer resin of ethylene-(meth)acrylic acid copolymer can be used for the outer jacket 5. In this case, both resins contain ethylene units.

The container body 2 can be manufactured by a method that includes an integral molding process in which the inner container 4 and the outer jacket 5 are integrally molded. As shown in Figures 7 and 8, in the integral molding process, the mouth portion 8 is fixed to a fixing portion 10 having an opening 10a, and the outer peripheral surface 4a (preferably the outer peripheral surface 4a and the bottom surface 4b) of the inner container 4 is placed in a mold 9 for injection molding, and the support rod 11 is inserted into the inner container 4 and pressed against the inner surface of the bottom surface 4b. This prevents the storage portion 7 of the inner container 4 from being displaced during injection molding.

In this state, the space outside the inner container 4 in the cavity 9a of the mold 9 is filled with resin to form the outer jacket 5. At this time, it is preferable to pressurize the inside of the inner container 4 so that the inner container 4 does not deform due to the resin pressure. Pressurization can be performed by blowing in water or air. The resin is filled into the cavity 9a from the gate 9b. It is preferable to position the gate 9b in a position opposite the bottom surface 4b (preferably the cut-off portion 7c) of the inner container 4. In this case, it is easier to fill the entire periphery of the inner container 4 with resin evenly.

It is preferable that the resin for injection molding has the fluidity required for injection molding at a temperature lower than the melting point of the resin constituting the outermost layer 4c1 of the inner container 4. The melting point of the resin for injection molding is, for example, 60 to 100°C, and preferably 70 to 90°C. Specifically, this melting point may be, for example, 60, 65, 70, 75, 80, 85, 90, 95, or 100°C, or may be within a range between any two of the values exemplified here.

The difference between the melting point of the resin for injection molding and the melting point of the outermost layer resin is preferably 5°C or more, more preferably 10°C or more, and even more preferably 20°C or more. This difference in melting point is, for example, 5 to 50°C, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50°C, and may be within a range between any two of the numerical values exemplified here.

The resin temperature during injection molding is preferably 180 to 230°C. If the temperature is too low, the pressure during injection may become high, and if the temperature is too high, air may be easily entrained during injection. Specific examples of this resin temperature are 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, and 230°C, and may be within a range between any two of the values exemplified here.

2. Second embodiment A second embodiment of the present invention will be described. This embodiment is similar to the first embodiment, and the main difference is that the inner container 4 is a so-called delaminating container having an outer shell 13 and an inner bag 14 as shown in Figures 11 and 12, and the inner bag 14 shrinks as the contents decrease. The following description will focus on the differences.

In this embodiment, as the contents of the peelable laminate container decrease, the inner bag 14 separates from the outer shell 13, causing the inner bag 14 to shrink. In such a container, outside air is less likely to enter the inner bag 14, suppressing deterioration of the contents.

As shown in FIG. 11, the outer shell 13 is composed of, for example, an outermost layer 13c1, an adjacent layer 13c2, and other layers 13c3. The inner bag 14 is composed of, for example, an outermost layer 14c1, an adhesive layer 14c2, and an inner surface layer 14c3. The outermost layer 13c1 and the adjacent layer 13c2 correspond to the outermost layer 4c1 and the adjacent layer 4c2 of the first embodiment, and the configuration and effects are also similar to those of the first embodiment.

The other layer 13c3, the outermost layer 14c1, the adhesive layer 14c2, and the inner surface layer 14c3 correspond to the other layer 4c3 of the first embodiment. The other layer 13c3 and the inner surface layer 14c3 are composed of low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, and mixtures thereof. The outermost layer 14c1 is a layer that has excellent peelability from the other layer 13c3, and is preferably composed of an ethylene-vinyl alcohol copolymer (EVOH) resin or the like. The adhesive layer 14c2 is preferably composed of an adhesive resin such as acid-modified polyolefin.

As shown in FIG. 12, the cutout 7c closes the bottom of each of the outer shell 13 and the inner bag 14, but since the cutout 7c is particularly weak in the outer shell 13, it is possible to open the cutout 7c in the outer shell 13 by applying an impact to the outer shell 13, thereby forming an outside air inlet 15. Outside air can be introduced between the outer shell 13 and the inner bag 14 through the outside air inlet 15. The outside air inlet 15 may be formed by perforating the outer shell 13. The outside air inlet 15 may be provided in the storage section 7 or in the mouth 8.

When the outside air inlet 15 of the inner container 4 is covered by the outer jacket 5, outside air cannot be introduced through the outside air inlet 15. For this reason, the outer jacket 5 is provided with a ventilation section 5c that connects the space outside the storage container 1 with the outside air inlet 15. The ventilation section 5c may be a through hole or a groove. The ventilation section 5c may be formed during injection molding, or may be formed by post-processing after injection molding.

If the mantle 5 does not cover the mouth 8, providing an outside air intake section 15 at the mouth 8 will eliminate the need for the ventilation section 5c.

When forming the ventilation section 5c during injection molding, for example, a pin can be placed at a location corresponding to the ventilation section 5c, and the pin can be removed from the mantle 5 when the container body 2 is removed from the mold 9.

It is preferable to pre-peele the inner bag 14 of the inner container 4 before the integral molding process. This is because it is easier to pre-peele the inner bag 14 before integrally molding the outer jacket 5 with the inner container 4.

<Pump 12>
The pump 12 is configured to discharge the contents from the inner container 4. When the inner container 4 is a delaminating container, it is preferable that the pump 12 is configured not to introduce outside air into the inner container 4.

As shown in FIG. 13, the pump 12 includes a main body 12a, a piston 12b, a nozzle 12c, and a tube 12d. The main body 12a includes a tube 12a1, a cylinder 12a2, and an upper wall 12a3. The inner surface of the tube 12a1 is provided with an engagement portion (female thread) (not shown) that engages with the engagement portion (male thread) 108a. The cylinder 12a2 is inserted into the mouth 8. The outer diameter of the cylinder 12a2 is approximately the same as the inner diameter of the mouth 8. The cylinder 12a2 is cylindrical, and the piston 12b is slidable within the cylinder 12a2. The internal space of the cylinder 12a2 is connected to the nozzle 12c and the tube 12d. The internal space of the cylinder 12a2 contains a pump mechanism that is composed of an elastic member and a valve. By sliding the piston portion 12b and activating the pump mechanism, the contents sucked up through the tube 12d can be expelled from the nozzle 12c.

3. Third embodiment A third embodiment of the present invention will be described with reference to Fig. 14. This embodiment is similar to the second embodiment, and differs mainly in that an outside air introduction section 15 is provided at the mouth 8 of the inner container 4. The following description will focus on the difference.

When the outer shell 13 is sealed, the outside air inlet 15 is not provided at the cutout 7c, so it is preferable to provide a through hole in the outer shell 13 to form the outside air inlet 15. In this case, it is preferable to provide the outside air inlet 15 in a portion of the inner container 4 that is not covered by the jacket 5. This is because in this case, it is not necessary to provide a ventilation section 5c in the jacket 5.

The outside air introduction section 15 is preferably provided at the mouth 8 as shown in FIG. 14, and is particularly preferably provided at a position covered by the tubular section 12a1 of the pump 12 shown in FIG. 12. In this case, the outside air introduction section 15 is not visible when the pump 12 is attached, which is aesthetically pleasing. The outside air introduction section 15 is ventilated to the outside through air passages such as the gap between the piston section 12b and the tubular section 12a1, and the gap between the bottom end of the tubular section 12a1 and the inner container 4.

The outside air inlet 15 is preferably provided on the flat portion 8b of the mouth 8. In this case, it is easy to form the outside air inlet 15 using a drill or other drilling tool. The flat portion 8b may be provided at a position closer to the storage portion 7 than the engaging portion 8a, or may be provided so as to separate the engaging portion 8a. In the latter case, there is an advantage that it is not necessary to lengthen the mouth 8 in order to provide the flat portion 8b.

1. Manufacturing of the container body 2 <Example 1>
An inner container 4 having the layer structure shown in Table 3 and the structure shown in Fig. 12 was produced by direct blow molding. The thickness of the storage section 7 of the inner container 4 at the center in the height direction was 1500 µm.

Each layer in Table 3 was made from the following materials.
LDPE/LLDPE layer: mixed resin of LDPE (melting point 110°C, manufactured by Asahi Kasei Corporation, model: F2206) and LLDPE (melting point 120°C, manufactured by Japan Polyethylene Corporation, model: NF325N) in a mass ratio of 50:50 PP layer: polypropylene (manufactured by Sumitomo Chemical Co., Ltd., model: FH3315)
EVOH layer: EVOH (manufactured by Mitsubishi Chemical Corporation, model: SF7503B)
Acid-modified PE/LDPE layer: Mixture of acid-modified polyethylene (manufactured by Mitsubishi Chemical Corporation, model: L522) and LDPE (melting point 110°C, manufactured by Asahi Kasei Corporation, model: F2206) in a mass ratio of 50:50 LDPE layer: LDPE (manufactured by Asahi Kasei Corporation, model: F2206)

Next, following the method described in the first embodiment, the outer jacket 5 was formed by injection molding at a resin temperature of 220°C so as to cover the outer periphery and bottom surface of the inner container 4, thereby producing the container body 2. The injection molding was performed using an ionomer resin of ethylene (meth)acrylic acid copolymer (manufactured by Dow Mitsui Polychemicals, model: PC2000, melting point 80°C).

Example 2
A container body 2 was produced in the same manner as in Example 1, except that a LDPE/ADH layer was used as the outermost layer 13c1 of the outer shell 13 instead of the LDPE/LLDPE layer.

The LDPE/ADH layer was a mixed resin of LDPE (melting point 110°C, manufactured by Asahi Kasei Corporation, model: F2206) and adhesive resin (melting point 120°C, manufactured by Mitsubishi Chemical Corporation, model: L522) in a mass ratio of 50:50, and the melting point of the mixed resin was 115°C.

<Comparative Example 1>
A container body 2 was produced in the same manner as in Example 1, except that a PP layer was used as the outermost layer 13c1 of the outer shell 13 instead of the LDPE/LLDPE layer.

The PP layer was made of polypropylene (Sumitomo Chemical Co., Ltd., model: FH3315) and had a melting point of 140°C.

2. Evaluation The following evaluations were performed on the above-mentioned Examples and Comparative Examples. The results are shown in Table 4. As shown in Table 4, the Examples had good deformability and adhesion. On the other hand, the Comparative Examples had poor deformability and adhesion.

<Deformability>
The inner container 4 inside the jacket 5 was visually inspected for deformation and evaluated according to the following criteria.
○: No deformation ×: Deformation

<Adhesiveness>
The container body 2 was cut vertically, and it was confirmed whether the inner container 4 could be peeled off from the outer jacket 5 by hand, and the peeling was evaluated according to the following criteria.
○: Cannot be peeled off even when pulled strongly by hand △: Can be peeled off when pulled strongly by hand ×: Can be peeled off easily by hand

1: Storage container 2: Container body 3: Opening member 4: Inner container 4a: Outer peripheral surface 4b: Bottom surface 4c1: Outermost layer 4c2: Adjacent layer 4c3: Other layers 5: Outer jacket 5a: Cylindrical portion 5b: Bottom portion 5c: Ventilation portion 7: Storage portion 7a: Body portion 7b: Bottom portion 7c: Cutting portion 8: Mouth portion 8a: Engagement portion 8b: Flat portion 9: Mold 9a: Cavity 9b: Gate 10: Fixing portion 10a: Opening 11: Support rod 12: Pump 12a: Main body portion 12a1: Cylindrical portion 12a2: Cylinder portion 12a3: Upper wall portion 12b: Piston portion 12c: Nozzle 12d: Tube 13: Outer shell 13c1: Outermost layer 13c2: Adjacent layer 13c3: Other layers 14 : Inner bag 14c1 : Outermost layer 14c2 : Adhesive layer 14c3 : Inner surface layer 15 : Outside air intake section

Claims (12)

The container body has an outer jacket integrally formed with the inner container so as to cover the outer peripheral surface of the inner container,
The mantle is an injection molded body,
The inner container is a blow-molded container formed by blow molding a parison,
The inner container has an outermost layer and an adjacent layer adjacent to the outermost layer,
the melting point of the outermost layer resin constituting the outermost layer is lower than the melting point of the adjacent layer resin constituting the adjacent layer,
A container , wherein the resin constituting the outer jacket has the same monomer units as the outermost layer resin . The container according to claim 1,
A storage container, wherein the difference in melting point between the outermost layer resin and the adjacent layer resin is 5° C. or more. The storage container according to claim 1 or 2,
A storage container, wherein the thickness of the outermost layer is 10% or more of the thickness of the inner container. The storage container according to any one of claims 1 to 3,
The outermost layer resin of the container comprises an unmodified polyolefin. The container according to claim 4,
The outermost layer resin of the container comprises an acid-modified polyolefin and the unmodified polyolefin. The storage container according to any one of claims 1 to 5,
The inner container has an outer shell and an inner bag, and is configured so that the inner bag shrinks as the contents decrease,
A containment vessel, wherein the outermost layer and the adjacent layer are provided on the outer shell. The container according to claim 6,
An outside air introduction section for introducing outside air is provided between the outer shell and the inner bag,
The outer jacket is provided with a ventilation section that communicates with the outside air introduction section. A method for manufacturing a storage container, comprising an integral molding step of integrally molding an inner container and an outer shell,
In the integral molding step, a resin is filled into a space outside the inner container in a cavity of the mold while the outer peripheral surface of the inner container is placed in the mold, thereby forming the outer jacket;
The inner container is a blow-molded container formed by blow molding a parison,
The inner container has an outermost layer and an adjacent layer adjacent to the outermost layer,
the melting point of the outermost layer resin constituting the outermost layer is lower than the melting point of the adjacent layer resin constituting the adjacent layer,
A method in which the resin constituting the mantle has the same monomer units as the outermost layer resin . 9. The method of claim 8,
The inner container has an outer shell and an inner bag, and is configured so that the inner bag shrinks as the contents decrease,
The method of claim 1, wherein the outermost layer and the adjacent layer are provided on the shell. 10. The method of claim 9,
An outside air introduction section for introducing outside air is provided between the outer shell and the inner bag,
The mantle is provided with a ventilation section that communicates with the outside air introduction section. The method according to any one of claims 8 to 10 ,
The method further comprises pressurizing the inside of the inner container during the integral molding process. The method according to any one of claims 8 to 11 ,
The method according to claim 1, wherein in the integral molding step, the resin is filled in a state in which the inner surface of the bottom surface of the inner container is pressed by a support rod inserted into the inner container.