JP7572609B2 - Double container - Google Patents

Description

The present invention relates to a double container.

Patent document 1 discloses a method for producing a double-walled container by blow molding an inner preform and an outer preform in a stacked state.

WO2004/071887

The inner bag is made up of the inner preform, and the outer shell is made up of the outer preform. As the contents inside the inner bag decrease, the inner bag shrinks, but the outer shell maintains its original state by introducing outside air into the intermediate space between the inner bag and the outer shell through an air inlet hole in the outer shell.

In this type of double-walled container, the inventors of the present invention have found that when they provide an air inlet hole at the bottom of the container for aesthetic reasons, it can be difficult to introduce air into the intermediate space between the inner bag and the outer shell.

The present invention was made in consideration of these circumstances, and provides a double container that allows outside air to be smoothly introduced into the intermediate space between the inner bag and the outer shell, even when an outside air inlet hole is provided at the bottom of the container body.

According to the present invention, there is provided a double container having an outer shell and an inner bag, the container body being configured such that the inner bag shrinks as the content decreases, the container body having a cylindrical body and a bottom provided at the lower end of the body, the bottom having a central recess provided at the center of the bottom and a peripheral portion surrounding the central recess, the outer shell having an outside air introduction hole in the central recess, and the peripheral portion having a spacer for forming a gap between the outer shell and the inner bag.

After careful study, the inventors found that when a central recess is provided at the bottom of the container body, a gap is unlikely to form between the inner bag and the outer shell in the peripheral portion surrounding the central recess, and that for this reason, providing an outside air introduction hole in the central recess makes it difficult for outside air to be introduced into the body of the container body. Based on this knowledge, the inventors discovered that by providing a spacer on the peripheral portion to form a gap between the outer shell and the inner bag, outside air can be smoothly introduced into the body through the peripheral portion from the outside air introduction hole at the bottom, which led to the completion of the present invention.

Various embodiments of the present invention will be described below. The embodiments described below can be combined with each other.
Preferably, in the double container described above, the spacer is a protrusion provided on the outer shell or the inner bag.
Preferably, in the dual container described above, the spacers are arranged radially.
Preferably, in the double container described above, the spacer is arranged to form an intermittent circle.
Preferably, in the double container described above, the container body is a double container formed by heating and blow molding an inner preform that becomes the inner bag and an outer preform that becomes the outer shell, with the inner preform that becomes the inner bag being covered with an outer preform that becomes the outer shell.
Preferably, the double container described above is one in which the inner preform has a positioning pin at the bottom of the inner preform, the outer preform has a positioning hole at the bottom of the outer preform, and the blow molding is performed with the positioning pin inserted into the positioning hole.

1A and 1B show a container body 2 of a double container 1 according to a first embodiment of the present invention, with FIG. 1A being a front view and FIG. 1B being a bottom view. 2A is a perspective view of the container body 2 of FIG. 1 as viewed from the bottom 7 side, and FIG. 2B is a cross-sectional perspective view of the vicinity of the bottom 7 of the outer shell 3 as viewed from the inside of the container. 3A is a cross-sectional view taken along line AA in FIG. 1B, and FIG. 3B is a cross-sectional view taken along line BB in FIG. 3A. FIG. 2 is a perspective view showing a state in which the inner preform 14 and the outer preform 13 are separated. 5 is a cross-sectional perspective view of the vicinity of a bottom portion 13c of the outer preform 13 of FIG. 4, as viewed from the inside of the outer preform 13. FIG. FIG. 6A is a perspective view of an assembly 15 formed by covering an outer preform 13 on an inner preform 14, and FIG. 6B is a perspective view of FIG. 6A seen from a different angle. FIG. 2 is a cross-sectional view showing the biaxially stretched blow molding process, illustrating the state in which the assembly 15 is attached to the mouth support mold 21. 8 is a cross-sectional view showing a state after the molding dies 23, 24 are closed and the bottom support die 22 supports the bottom 13c of the outer preform 13 from the state shown in FIG. 7. FIG. 9 is a cross-sectional view showing the state after the support rod 25 is extended and the bottom support mold 22 is retracted from the state shown in FIG. 8 to longitudinally stretch the assembly 15. FIG. 6 is a cross-sectional perspective view corresponding to FIG. 5, showing an outer preform 13 having intermittent circular projections 13c1. FIG. 11 is a perspective view showing an inner preform 14 having radial projections 14c2 on a bottom portion 14c. FIG. 13 is a perspective view showing an inner preform 14 having a bottom 14c on which intermittent circular projections 14c2 are provided. FIG. 13 is an enlarged view of the vicinity of a bottom 14g of an inner preform 14 of a modified example. FIG.

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

1. First embodiment As shown in Fig. 1, a double container 1 according to a first embodiment of the present invention includes a container body 2. As shown in Fig. 3A, the container body 2 has an outer shell 3 and an inner bag 4, and is configured so that the inner bag 4 shrinks as the content decreases.

As shown in FIG. 1, the container body 2 has a mouth 5, a body 6, and a bottom 7. The mouth 5 has an engagement portion 5a to which a pump (not shown) can be attached. The engagement portion 5a is a male thread portion in the case of a screw-type pump, and is an annular projection protruding in the circumferential direction in the case of a tap-type pump. The mouth 5 is provided to extend from the upper end 6a of the body 6. The mouth 5 is cylindrical. The body 6 has a larger outer diameter (in this specification, "outer diameter" means the circumscribed circle diameter when the cross section is not circular) than the mouth 5.

The body 6 is cylindrical, and the bottom 7 is provided at the lower end of the body 6 and closes the lower end of the body 6. The bottom 7 has a central recess 7a provided at the center of the bottom 7 and a peripheral portion 7b surrounding the central recess 7a.

2A, the central recess 7a is provided with a locking portion 7a1, an outside air introduction hole 7a2, an annular protrusion 7a3, and a positioning recess 7a4. As shown in FIG. 3A, the locking portion 7a1 is formed by inserting a locking protrusion 4a provided on the inner bag 4 into an insertion hole 3a provided on the outer shell 3. The locking portion 7a1 prevents the inner bag 4 from coming off the outer shell 3. The outside air introduction hole 7a2 is a through hole that penetrates the outer shell 3, and as the inner bag 4 contracts, outside air is introduced into the intermediate space between the outer shell 3 and the inner bag 4 through the outside air introduction hole 7a2. The locking portion 7a1 and the outside air introduction hole 7a2 are arranged in the annular protrusion 7a3. The positioning recess 7a4 is used to position the container body 2 in the circumferential direction when printing or the like is performed on the container body 2.

The peripheral portion 7b is provided with a grounding portion 7b1 and a peripheral recess 7b2. The grounding portion 7b1 is the portion that comes into contact with the mounting surface on which the container body 2 is placed when the container body 2 is erected. If the entire peripheral portion 7b were to be the grounding portion 7b1, the central recess 7a would become an airtight space between the container body 2 and the mounting surface when the container body 2 is erected, and there is a risk that the introduction of outside air through the outside air inlet 7a2 would be hindered. Therefore, the peripheral recess 7b2 is provided as an air passage to prevent the inside of the central recess 7a from becoming an airtight space.

When the contents in the inner bag 4 are discharged by the pump attached to the mouth 5, the inner bag 4 shrinks and tries to move away from the outer shell 3. At this time, outside air is introduced into the space between the inner bag 4 and the outer shell 3 through the outside air introduction hole 7a2. On the other hand, as shown in FIG. 3A, since the peripheral portion 7b has a small radius of curvature, the inner bag 4 does not easily separate from the outer shell 3 at the peripheral portion 7b, and it is difficult to form an air passage through which the outside air introduced from the outside air introduction hole 7a2 passes. Therefore, it is difficult for outside air to be introduced into the body portion 6. In this case, there is a problem that the outer shell 3 shrinks together with the inner bag 4 as the contents decrease. Therefore, in this embodiment, a spacer 9 is arranged between the outer shell 3 and the inner bag 4. In this embodiment, a protrusion 3b protruding from the outer shell 3 toward the inner bag 4 is provided as the spacer 9. When the spacer 9 is provided, a gap 8 is formed between the outer shell 3 and the inner bag 4 at a position adjacent to the spacer 9, and the gap 8 forms an air passage connecting the body 6 and the bottom 7, making it easier for outside air introduced from the outside air introduction hole 7a2 to be introduced into the body 6 through the peripheral portion 7b. The spacer 9 is provided radially so as to straddle the bottom 7 and the body 6, which makes it easier to form an air passage spanning the bottom 7 and the body 6.

As shown in Figures 4 to 6, the container body 2 can be formed by placing an outer preform 13, which will become the outer shell 3, over an inner preform 14, which will become the inner bag 4, and then heating the inner preform 14 and the outer preform 13 to perform biaxial stretch blow molding.

As shown in FIG. 4, the inner preform 14 is a cylindrical member with a bottom, and includes a mouth portion 14a, a body portion 14b, and a bottom portion 14c. A flange 14a1 is provided at the open end of the mouth portion 14a. A positioning pin 14c1 is provided at the bottom portion 14c.

As shown in FIG. 4, the outer preform 13 is a bottomed cylinder having an opening 13a, a body 13b, and a bottom 13c. As shown in FIG. 5, the inner surface of the bottom 13c of the outer preform 13 is provided with radially arranged protrusions 13c1. The bottom 13c is provided with positioning holes 13c2 and outside air introduction holes 13c3. As shown in FIG. 6B, the outer surface of the bottom 13c is provided with an annular protrusion 13c4. The positioning holes 13c2 and outside air introduction holes 13c3 are arranged in the inner region of the annular protrusion 13c4. The outer preform 13 is sized to allow the inner preform 14 to be inserted therein.

The inner preform 14 and the outer preform 13 can be formed by blow molding or injection molding of thermoplastic resins such as polyester (e.g., PET) or polyolefin (e.g., polypropylene, polyethylene). In one example, the inner preform 14 is formed by blow molding of polypropylene, and the outer preform 13 is formed by injection molding of PET. By making the inner preform 14 and the outer preform 13 from different materials, welding to each other during blow molding is suppressed. In addition, when the outer preform 13 is formed by injection molding, the outside air introduction hole 13c3 can be formed during injection molding, so the effort of post-processing can be saved.

2. Biaxially stretched blow molding Biaxially stretched blow molding can be carried out by the following method.

First, as shown in FIG. 6, the outer preform 13 is placed over the inner preform 14 (in other words, the inner preform 14 is inserted into the outer preform 13) to form an assembly 15. At this time, the flange 14a1 is abutted against the open end of the mouth portion 13a, and the positioning pin 14c1 is inserted into the positioning hole 13c2. This positions the inner preform 14 and the outer preform 13 relative to each other. In this state, the mouth portion 14a faces the mouth portion 13a, and the body portion 14b faces the body portion 13b.

Next, the assembly 15 is heated to soften it.

Next, the assembly 15 is placed in a blow molding die, and with the mouth portion 13a and the annular protrusion 13c4 supported by a jig, air is blown into the inner preform 14 to expand the assembly 15 and make it adhere to the inner surface of the die cavity. At this time, a support rod (not shown) may be pressed against the inner bottom surface of the inner preform 14 to prevent the assembly 15 from shaking within the die. Also, a recess into which the support rod fits may be provided on the inner bottom surface of the inner preform 14 to make it easier to fix the support rod to the inner preform 14.

By blow molding, the assembly 15 expands to obtain the container body 2 shown in Figures 1 to 3. The mouth parts 13a and 14a become the mouth part 5, the body parts 13b and 14b become the body part 6, and the bottom parts 13c and 14c become the bottom part 7. The protrusion 13c1, the annular protrusion 13c4, and the outside air introduction hole 13c3 become the protrusion 3b, the annular protrusion 7a3, and the outside air introduction hole 7a2, respectively. During blow molding, the mouth parts 13a and 14a, the annular protrusion 13c4, and the area inside it are hardly deformed, and other parts are mainly deformed. Since the outside air introduction hole 13c3 is located in the area inside the annular protrusion 13c4, it is suppressed from being deformed and blocked during blow molding. The flange 14a1 becomes the flange 4b that covers the open end of the mouth part 5 of the container body 2, as shown in Figure 1A.

After blow molding, the positioning hole 13c2 becomes the insertion hole 3a shown in FIG. 3A, and the positioning pin 14c1 is inserted into the insertion hole 3a. The positioning pin 14c1 is then deformed (i.e., crushed or bent) to become the locking protrusion 4a shown in FIG. 3A. This forms the locking portion 7a1 of the container body 2.

3. Details of Biaxial Stretch Blow Molding In one example, the biaxial stretch blow molding described above can be performed using a mold unit 20 shown in Figures 7 to 9. The mold unit 20 includes a mouth support mold 21, a bottom support mold 22, and molding molds 23 and 24.

The mouth support mold 21 is configured to be able to support the mouth 13a of the outer preform 13. An insertion hole 21a is provided in the mouth support mold 21, and a support rod 25 is inserted into the insertion hole 21a. The support rod 25 can be extended and retracted by a drive mechanism (not shown). The bottom support mold 22 is driven by a drive mechanism 22c and configured to be able to move in the vertical extension direction (up and down direction in FIG. 7). The molding molds 23 and 24 can be opened and closed, and each have a cavity surface 23a and 24a. The cavity surfaces 23a and 24a come together to form a cavity having a shape corresponding to the outer shape of the container body 2.

This method includes a preform heating step, a bottom support step, a stretching step, and a blow molding step.

<Preform heating process>
In the preform heating step, the assembly 15 formed by covering the inner preform 14 with the outer preform 13 is attached to the mouth support mold 21 as shown in Fig. 7, and in this state, the assembly 15 is heated and softened. The assembly 15 may be heated while it is disposed between the molding dies 23 and 24, or may be heated outside the space between the molding dies 23 and 24. Furthermore, before the preform heating step, the tip of the support rod 25 may be abutted against the inner bottom surface of the inner preform 14. This prevents the softened assembly 15 from shaking.

<Bottom support process>
In the bottom support step, as shown in FIG. 8, the bottom support mold 22 moves toward the bottom 13c of the outer preform 13, and supports the bottom 13c of the outer preform 13 with the bottom support mold 22. The bottom support mold 22 is provided with a recess 22a capable of accommodating the annular convex portion 13c4, and the bottom support mold 22 preferably supports the bottom 13c so that the annular convex portion 13c4 is accommodated in the recess 22a. This prevents the annular convex portion 13c4 and its inner region from being stretched during the blow molding step. The recess 22a is preferably annular. In addition, the bottom support mold 22 preferably includes a recess 22b capable of accommodating the positioning pin 14c1, and supports the bottom 13c so that the positioning pin 14c1 is accommodated in the recess 22b. This prevents the positioning pin 14c1 from interfering with the bottom support mold 22. FIG. 8 shows the molding dies 23, 24 in a closed state, but the molding dies 23, 24 may be closed at any time before the blow molding step, and may be closed after the longitudinal stretching step.

<Longitudinal Stretching Process>
In the longitudinal stretching step, as shown in Figures 8 to 9, the support rod 25 is pressed against the inner bottom surface of the inner preform 14 and stretched, thereby stretching the assembly 15 in the longitudinal direction (the vertical direction in Figure 9). At this time, it is preferable to move the bottom support mold 22 backward in synchronization with the extension of the support rod 25. This allows the assembly 15 to be stably stretched. Note that the longitudinal stretching step can also be performed in a state in which the bottom 13c is not supported by the bottom support mold 22, so the bottom support step may be performed after the longitudinal stretching step.

<Blow molding process>
In the blow molding process, air is blown into the inner preform 14 from the state shown in Fig. 9 to stretch (i.e. expand) the assembly 15 in the lateral direction and shape it into the shape of the cavity surfaces 23a, 24a. The air can be blown in through the air passage 26 between the mouth support mold 21 and the support rod 25, but for example, an air passage may be provided in the support rod 25 so that the air can be blown out from the side of the support rod 25.

In this embodiment, air is blown in while the bottom 13c of the outer preform 13 is supported by the bottom support mold 22, so stretching of the bottom 13c of the outer preform 13 is suppressed.

The blow molding process can also be performed simultaneously with the vertical stretching process. That is, air can be blown into the inner preform 14 while the assembly 15 is being stretched in the vertical direction. Also, the vertical stretching process can be omitted, and air can be blown in after the bottom support process without stretching the assembly 15 in the vertical direction.

4. Other embodiments: In the above embodiment, the spacers 9 are provided radially, but the spacers 9 may have another shape. For example, the spacers 9 may be arranged to form an intermittent circle. In this case, an air passage is formed in the missing portion of the circle. It is preferable that a plurality of intermittent circles are arranged concentrically. For example, such a spacer 9 can be formed by using an outer preform 13 having intermittent circular protrusions 13c1 as shown in FIG. 10.
In the above embodiment, the protrusion 3b protruding from the outer shell 3 toward the inner bag 4 is formed by providing the protrusion 13c1 on the outer preform 13. However, as shown in Figures 11 and 12, a protrusion (spacer) protruding from the inner bag 4 toward the outer shell 3 may be formed by providing a protrusion 14c2 (e.g., a radial protrusion as shown in Figure 11 or an intermittent circular protrusion as shown in Figure 12) on the bottom 14c of the inner preform 14.
The spacer 9 may be formed of a separate member. The spacer 9 can be disposed between the outer shell 3 and the inner bag 4 by performing blow molding in a state in which a member serving as a spacer is disposed between the inner preform 14 and the outer preform 13.

5. Invention from Another Viewpoint When the inner preform 14 is a blow molded body (more specifically, a direct blow molded body), a pinch-off portion 14h is formed at the position where the parison is closed in the bottom portion 14g of the inner preform 14, as shown in Fig. 13. Since the strength of the pinch-off portion 14h is relatively weak, there is a risk that the pinch-off portion 14h will rupture if a portion near the pinch-off portion 14h is stretched forcefully during biaxial stretch blow molding.

In one example, as shown in FIG. 13, the inner preform 14 has a multi-layer structure, and includes, from the inside, an innermost layer 14d, a gas barrier layer (e.g., an EVOH layer) 14e, and an outermost layer 14f. The innermost layer 14d and the outermost layer 14f are made of polyolefin (e.g., polyethylene, polypropylene) or PET. In the pinch-off portion 14h, the opposing gas barrier layers 14e1 and 14e2 are connected to each other, or if they are separated, the gap G between them is very small. If the area near the pinch-off portion 14h is stretched forcefully during biaxial stretch blow molding, the gas barrier layer 14e may tear or the gap G may become large, resulting in problems such as a decrease in gas barrier properties.

As explained in "2. Biaxially stretched blow molding" and "3. Details of biaxially stretched blow molding", the above problem can be solved by expanding the assembly 15 while suppressing the stretching of the bottom 13c of the outer preform 13. Since the pinch-off portion 14h is positioned opposite the bottom 13c of the outer preform 13, when the stretching of the bottom 13c is suppressed, the stretching of the area near the pinch-off portion 14h is also suppressed, and the above problem is solved.

In "2. Biaxially stretched blow molding," the bottom 13c of the outer preform 13 is provided with an annular protrusion 13c4 to increase the rigidity of the bottom 13c and suppress the stretching of the bottom 13c. The structure provided to increase the rigidity of the bottom 13c may be a reinforcing structure other than the annular protrusion 13c4.

In "3. Details of biaxial stretch blow molding," the bottom 13c of the outer preform 13 is supported by the bottom support mold 22 while the blow molding process is performed, thereby suppressing the stretching of the bottom 13c. In the above explanation, the annular convex portion 13c4 is accommodated in the concave portion 22a, but even if the bottom 13c does not have the annular convex portion 13c4, the bottom 13c is supported by the bottom support mold 22, and the stretching of the bottom 13c is suppressed by the friction between the bottom 13c and the bottom support mold 22.

In consideration of the above, according to the present invention,
A method for manufacturing a double container, comprising the steps of:
A blow molding process is provided.
The blow molding step is performed by heating and softening the inner preform and the outer preform in a state where the inner preform is covered with the outer preform, and then blowing air into the inner preform in that state.
The inner preform is a blow molded body,
A method is provided, wherein the blow molding step is performed with restrained stretching of a bottom portion of the outer preform.

Preferably, the outer preform comprises a reinforcing structure that inhibits elongation of a bottom portion of the outer preform.
Preferably, the reinforcing structure is an annular protrusion provided on the bottom of the outer preform.
Preferably, the blow molding step is performed in a state in which the bottom of the outer preform is supported by a bottom support mold to suppress stretching of the bottom.

Also, from another perspective,
A method for manufacturing a double container, comprising the steps of:
A blow molding process is provided.
The blow molding step is performed by blowing air into the inner preform while the inner preform and the outer preform are covered with the inner preform and heated to soften the inner preform and the outer preform,
The inner preform is a blow molded body,
A method is provided, wherein the outer preform has an annular protrusion at its bottom.

In addition, in the invention of another aspect, the position of the outside air introduction hole is not limited, and it may be provided in any of the mouth part 5, the body part 6, or the bottom part 7 of the container body 2. Also, the spacer 9 for forming a gap between the outer shell 3 and the inner bag 4 is not essential.

1: Double container 2: Container body 3: Outer shell 3a: Insertion hole 3b: Protrusion 4: Inner bag 4a: Locking protrusion 4b: Flange 5: Mouth 5a: Engagement portion 6: Body 6a: Upper end 7: Bottom 7a: Central recess 7a1: Locking portion 7a2: Outside air introduction hole 7a3: Annular protrusion 7a4: Positioning recess 7b: Peripheral portion 7b1: Grounding portion 7b2: Peripheral recess 8: Gap 9: Spacer 13: Outer preform 13a: Mouth 13b: Body 13c: Bottom 13c1: Protrusion 13c2: Positioning hole 13c3: Outside air introduction hole 13c4: Annular protrusion 14: Inner preform 14a: Mouth 14a1: Flange 14b: Body 14c: Bottom 14c1 : Positioning pin 14c2 : Protrusion 14d : Innermost layer 14e : Gas barrier layer 14e1 : Gas barrier layer 14e2 : Gas barrier layer 14f : Outermost layer 14g : Bottom 14h : Pinch-off portion 15 : Assembly 20 : Mold unit 21 : Mouth support mold 21a : Insertion hole 22 : Bottom support mold 22a : Recess 22b : Recess 22c : Driving mechanism 23 : Mold 23a : Cavity surface 24 : Mold 24a : Cavity surface 25 : Support rod 26 : Air passage G : Gap

Claims (7)

A double container having an outer shell and an inner bag, the inner bag comprising a contractible container body,
The container body includes a cylindrical body and a bottom provided at a lower end of the body,
The bottom portion includes a central recess provided at the center of the bottom portion and a peripheral portion surrounding the central recess,
An air inlet hole is provided in the outer shell in the central recess,
A spacer is provided on the peripheral portion to form a gap between the outer shell and the inner bag ,
The spacer is provided so as to span the bottom and the body . The double container according to claim 1,
The spacer is a protrusion provided on the outer shell or the inner bag. The double container according to claim 1 or 2,
The spacers are arranged radially. The double container according to claim 1 or 2,
The spacers are arranged to form an intermittent circle. A method for manufacturing a double container according to any one of claims 1 to 4,
a method for forming the container body by heating and blow molding an inner preform that will become the inner bag and an outer preform that will become the outer shell, the inner preform and the outer preform being covered with each other. 6. The method of claim 5,
The inner preform has a positioning pin at a bottom of the inner preform,
The outer preform has a positioning hole at a bottom portion of the outer preform,
The blow molding is performed with the positioning pins inserted into the positioning holes. 7. The method of claim 5 or claim 6 ,
The method comprises heating and blow molding a preform having a portion that will become the inner bag and a portion that will become the outer shell, thereby forming the container body .