JP2001080677A - Composite container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite container having inner and outer containers fixed firmly not by bonding nor fusion bonding. SOLUTION: A composite container 1 is provided with an inner container formed of a resin and having a neck section 2a and a shoulder section 2c and an outer container formed of a pulp and having a sending-up neck section 3a standing up in the height direction of the container, and the inner container is stored in the outer container in the state of extending outwardly the neck section 2a of the inner container from the standing-up neck section 3a of the outer container, and the standing-up neck section 3a of the outer container is clamped by a flange section 4 formed on the outer side face of the neck section 2a of the inner container and the shoulder section 2c of the inner container 2 to fix the inner container with the outer container 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite container provided with an outer body made of pulp and an inner body made of resin.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 6-278771 discloses that a paper outer container is fitted into a fitting portion provided at an upper end of a thin plastic inner container. Describes a composite container in which an inner container and an outer container are integrated. However, in order to firmly fit and integrate the inner container and the outer container in this composite container, high dimensional accuracy of the inner container and the outer container in the fitting portion is required, so that the manufacturing cost is increased. I will. Also, depending on the structure of the fitting portion, it may be difficult to separate the inner container and the outer container when disposing of the composite container.

[0003] Japanese Patent Application Laid-Open No. 7-41046 discloses that a plastic bag container in which a plastic bag is fixed to a plastic mouth frame is inserted into a paper container, and the mouth frame is opened at the opening of the paper container. A double container detachably fitted or adhered to the container is described. However, in this double container, the number of parts and the number of manufacturing steps are increased, resulting in high manufacturing costs. In addition, since the amount of plastic used increases, the amount of the portion discarded as incombustibles increases.

Japanese Patent Application Laid-Open Nos. 59-134153 and 58-151570 disclose a composite container comprising an inner container having a flange at the mouth and neck and an outer container. It is described that a portion is sandwiched between the flange and a wall of an inner container connected to the mouth and neck. However, this composite container requires (1) sufficient cooling, so that the molding cycle becomes longer and the production cost becomes higher. (2) If the cooling is insufficient, the flange of the inner container and the above-mentioned inner container will not be formed. When the peripheral edge of the opening of the outer container is sandwiched between the wall and the wall, there is a problem in that the dimensions vary, and (3) when the shape shapeability is poor, rattling occurs.

[0005] A composite container in which an outer container made of paper and an inner container made of plastic are fixed by bonding or fusion is also known. However, in this composite container, bonding and fusion between the outer container and the inner container are expensive, and the amount of plastic used increases. Further, when disposing of the composite container, it may be difficult to separate the inner container and the outer container.

Accordingly, an object of the present invention is to provide a composite container in which the inner and outer containers are firmly fixed without adhesion or fusion. Another object of the present invention is to provide a composite container in which the inner and outer containers can be easily separated and disposed.

[0007]

[Means for Solving the Problems]

In producing a composite container from an outer container made of pulp and an inner container made of resin, the present inventors, particularly when the inner container is formed by blow molding, the inner container formed by blow molding is cooled. It was found that the shrinkage phenomenon caused the fixing force of the outer container by the inner container.

The present invention has been made on the basis of the above findings, and is made of a resin made of resin having an open mouth and neck, a body, a shoulder connecting the mouth and neck and the body, and a bottom. A composite container comprising: an inner container; and an outer container made of pulp having an opening having a size larger than the opening of the mouth and neck of the inner container and having a standing mouth and neck standing upright in the height direction of the container. The inner container is housed in the outer container with the mouth and neck of the inner container extending outward from the standing mouth and neck of the outer container. A composite in which the mouth and neck are sandwiched between a flange formed on the outer surface of the mouth and neck in the inner container and the shoulder in the inner container, and the inner container and the outer container are fixed. By providing a container (hereinafter referred to as this invention when referred to as the first invention) It is those that have achieved the serial purpose.

The present invention also provides, as a preferred method of manufacturing the composite container, a bottomed parison having a flange on the outer surface near the opening, wherein the lower surface of the flange is above the neck of the upright opening in the outer container. After being inserted into the outer container through the upright neck portion so as to be in contact with the end surface, the parison is blow-molded to form the inner container having a shape corresponding to the inner shape of the outer container, An object of the present invention is to provide a method of manufacturing a composite container in which the inner container is cooled and contracted so that the upright neck portion of the outer container is held between the flange portion and the shoulder portion of the inner container.

The present invention is also a composite container comprising a pulp outer container and a resin inner container housed in the outer container, wherein the inner container is provided with a body portion inward of the container. A convex portion having a predetermined shape is formed toward the outer container, and the outer container has a shape capable of fitting with the convex portion at a position corresponding to the convex portion in the outer container under the state where the inner container is housed. The convex portion is formed toward the inside of the container, and the convex portion formed on the inner container and the convex portion formed on the outer container are fitted, and the inner container and the outer container are formed. Fixed composite container (hereinafter referred to as the second invention when referring to the second invention)
The above object has been achieved by providing

The present invention also provides, as a preferred method of manufacturing the composite container, a method of inserting a bottomed parison into the outer container in which a convex portion having a predetermined shape is formed on the body toward the inside of the container, and then removing the parison. Blow molding to form the inner container having a shape corresponding to the inner shape of the outer container, and then cooling and shrinking the inner container, thereby forming the convex portion of the outer container by blow molding. An object of the present invention is to provide a method of manufacturing a composite container sandwiched by convex portions formed on an inner container.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. First, FIG.
A preferred embodiment of the first invention will be described with reference to FIG.

FIG. 1 shows a partially cutaway front view of an embodiment of the composite container of the first invention. The composite container 1 has a cylindrical bottle shape and includes a resin inner container 2 and a pulp outer container 3. The inner container 2 is housed in the outer container 3, and the outer surface of the inner container 2 and the inner surface of the outer container 3 are in close contact with each other.

The inner container 2 includes an upper opened mouth and neck 2
a, a torso 2b, a shoulder 2c connecting the mouth and neck 2a and the torso 2b, and a bottom 2d. On the other hand, the outer container 3
A standing mouth and neck 3a, a trunk 3b, which stand in the height direction of the container,
It has a shoulder 3c connecting the upright neck 3a and the trunk 3b, and a bottom 3d. The standing mouth and neck 3a has an opening whose size is larger than the opening of the mouth and neck of the inner container 2 (hereinafter referred to as the inner mouth and neck) 2a. And the inner container 2
The inner container mouth neck 2a is accommodated in the outer container 3 in a state where the inner container mouth neck 2a extends outward from the standing mouth neck 3a of the outer container 3.

The inner container 2 is made of high-density polyethylene, low-density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, propylene-butene copolymer, ethylene-propylene-butadiene copolymer, etc. Polyolefin-based resin; polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, copolymerized polyester of terephthalic acid, isophthalic acid and ethylene glycol, copolymerized polyester of terephthalic acid, isophthalic acid and 1,4-cyclohexanedimethanol, terephthalic Polyester resin such as copolymerized polyester of acid, isophthalic acid, ethylene glycol and propylene glycol; polyamide resin such as nylon 6, nylon 6,6, nylon 12, and polystyrene , High impact polystyrene, polystyrene-based resins polymethyl styrene and the like; and a thermoplastic resin such as. At the time of use, one kind or two or more kinds can be used in combination or in a multilayer. In particular, when the inner container 2 is formed by injection stretch blow molding as described later, polypropylene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, propylene-butene copolymer, polyethylene terephthalate, etc. Preferably.

The thickness of the inner container 2 depends on the method of manufacturing the inner container 2. However, even when the inner container 2 is not filled with the contents, the shape and the self-sustainability are maintained and the inner container 2 is not separated from the outer container 3. It is preferably a thickness. Specifically, 30 ~
It is preferably 300 μm, particularly preferably 30 to 150 μm. If the thickness of the inner container 2 is too large, the amount of resin used will increase, resulting in an increase in the amount of the portion discarded as incombustibles, which will adversely affect the environment. It is preferred that

On the other hand, the outer container 3 is made of pulp as described above. For example, a molded product manufactured by a pulp molding method, a product manufactured from paperboard (cardboard), a product manufactured from corrugated cardboard, and the like are used. In the present embodiment, a molded body manufactured by a pulp molding method that easily obtains a desired shape is used as the outer container 3.

The thickness of the outer container 3 is 0.1 to 3 mm, particularly 0.4 mm, since it is necessary to have strength not to be crushed at the time of dropping, stacking and use, and to minimize the amount of waste. It is preferably about 2 mm.

Thus, in the composite container 1 of the present embodiment, as shown in FIG. 2, which is an enlarged sectional view of a main part of the composite container 1, an outer surface near the lower end of the inner container neck portion 2a has A flange portion 4 is formed over the entire circumference. The upright neck 3a of the outer container 3 is sandwiched between the flange 4 and the shoulder 2c of the inner container 2, and the inner container 2 and the outer container 3 are fixed. By fixing the inner container 2 and the outer container 3 in this manner, it is not necessary to fix the inner container 2 and the outer container 3 by bonding or fusion, and the inner container 2 and the outer container 3 can be easily separated when the composite container 1 is discarded. In particular, as described later, when the inner container 2 is formed by blow molding, by controlling the cooling and shrinking of the inner container 2 during molding,
The flange portion 4 and the shoulder portion 2c are respectively indicated by arrows A in FIG.
A ′ is contracted in the direction indicated by A ′, and the flange portion 4 and the shoulder portion 2 c
Can control the pinching force (fixing force). Further, since the standing mouth neck portion 3a of the outer container 3 is located at the mouth neck portion of the composite container 1, there is an advantage that the buckling strength of the mouth neck portion is increased. In particular, in the inner container 2, a portion facing the standing mouth neck 3 a of the outer container 3 (2 in FIG. 2)
If the thickness of the portion indicated by c ′) is larger than the thickness of the body 2b of the inner container 2, the buckling strength is further increased.

As shown in FIG. 2, between the inner container 2 and the outer container 3, there is a standing neck 3a of the outer container 3, a flange 4 of the inner container 2, and a shoulder 2c of the inner container 2. An annular space 5 is formed. Due to the presence of this space 5, as will be described later, when the inner container 2 is formed by blow molding, the space 5 acts as a heat insulating part, and the shrinkage of the inner container 2 increases, and a large fixing force is applied. appear. Also, when the composite container 1 is discarded, the neck 3a of the upright opening of the outer container 3 is easily torn off, and the inner container 2 and the outer container 3
There is also an advantage that can be easily separated.

Next, a preferred embodiment of the second invention will be described with reference to FIG. In the second invention, the same points as those of the first invention are not particularly described, but the detailed description of the first invention is appropriately applied. In FIG. 3, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals.

The composite container 1 shown in FIG. 3 has substantially the same shape as the composite container shown in FIG. The difference between the composite container 1 shown in FIG. 3 and the composite container shown in FIG. 1 is that a convex portion 1e is provided on the body 1b of the composite container 1 shown in FIG. This is the point formed over the entirety.

The convex portion 1e will be described in detail. The convex portion 1e includes a convex portion (hereinafter referred to as an inner container convex portion) 2e formed on the body 2b of the inner container 2 toward the inside of the container. A convex portion (hereinafter, referred to as an outer container convex portion) 3e formed on the body portion 3b of the outer container 3 toward the inside of the container. The outer container protrusion 3e is formed at a position corresponding to the inner container protrusion 2e in the outer container 3 in a state where the outer container 3 houses the inner container 2. Further, the outer container convex portion 3e is provided with an inner container convex portion 2e.
It has a shape that can be fitted. The inner container protrusion 2e and the outer container protrusion 3e are formed over the entire circumference of the body 2b of the inner container 2 and the body 3b of the outer container 3, respectively.

In the composite container 1 according to the present embodiment, the inner container convex portion 2e and the outer container convex portion 3e are fitted, and the inner container 2 and the outer container 3 are fixed. Inner container 2
By fixing the inner container 2 and the outer container 3 in this manner, it is unnecessary to fix the inner container 2 and the outer container 3 when disposing of the composite container 1 as in the case of the first invention. Can be separated. In particular, as described later, when the inner container 2 is formed by blow molding, the portion of the inner container convex portion 2e is stretched at a lower area ratio than other portions of the inner container 2, so that It becomes thicker than other parts, and the post-shrinkage becomes large. As a result, opposing rising portions 2f, 2f in the inner container convex portion 2e are indicated by arrows B, B 'in FIG.
, Ie, the rising portions 2f, 2f contract in the direction of approaching each other, and the outer container convex portion 3e becomes the inner container convex portion 2e.
And the fixing force is further increased. In addition, by forming the convex portion toward the inside of the container during blow molding, the thickness of the convex portion can be increased as compared with the case where the convex portion is formed toward the outside of the container, and the convex portion is broken. And the like can be effectively prevented.

Next, a preferred method of manufacturing the composite container of the present invention will be described with reference to FIG. 4, taking the method of manufacturing the composite container of the first embodiment of the first invention as an example. In FIG. 4, (a) is a step of loading the outer container and inserting a parison,
(B) is an outer container suction and parison stretching blow step,
(C) is a step of coating the inner surface of the outer container with the stretch-blown parison.

In the present manufacturing method, the inner container is formed by injection stretching blow. First, as shown in FIG. 4A, a molding die 10 including a pair of split dies 12 and 13 is prepared. The molding die 10 has an outer container accommodating portion 14 having a predetermined shape formed therein by assembling the split dies 12 and 13. The shape of the outer container housing 14 corresponds to the outer shape of the outer container 3 housed therein. The outer container accommodating portion 14 communicates with the outside of the molding die 10 through a parison insertion port 15 opened to the outside. Each split mold 1
A plurality of communication passages 16 communicating from the inside (that is, the inner surface of the outer container accommodating portion 14) to the outside are formed in the members 2 and 13. In particular, the communication path 16 is located at a position corresponding to a corner of the outer container 3 in the molding die 10 in a state where the outer container 3 is loaded or a position near the corner (that is, a corner of the outer container accommodating portion 14 or a vicinity thereof). Position), the outer container 3
This is preferable because the inner container 2 can be brought into close contact with the inner surface without any gap. Each communication passage 16 is connected to suction means (not shown) such as a suction pump. In each of the split dies 12, 13, a flow path 17 for flowing cooling water is formed.

The outer container 3 made of a pulp molded article is transported to a predetermined position of the mold 10 (not shown) in the mold open state, and the mold 10 is closed at this position. The container 3 is loaded into the outer container housing portion 14. At the same time, a resin bottomed parison 11 preheated to a predetermined temperature.
Is inserted into the outer container 3 through the parison insertion port 15 and further through the upright neck 3a of the outer container 3. Parison 11
Has a flange 11a on the outer surface near the opening. The flange portion 11a is formed by the flange portion 4 of the inner container 2 formed by blow molding the parison 11.
Becomes The parison 11 is inserted such that the lower surface of the flange portion 11a of the parison 11 comes into contact with the upper end surface of the neck 3a of the upright opening in the outer container 3.

The parison 11 is preheated to a predetermined temperature before being inserted into the outer container 3. For the preheating, a temperature control pot generally used in blow molding is used. The preheating temperature can be the same as in the blow molding of the parison 11.

After the parison 11 is inserted into the outer container 3, as shown in FIG. 4 (b), the interior of the outer container housing 14 is suctioned under reduced pressure through the communication passage 16 toward the outside of the molding die 10.
That is, the outer container 3 is sucked out of the molding die 10. Under this condition, the stretch pin 18 is inserted into the parison 11 to stretch the parison 11 and to blow air into the parison 11. Thereby, the parison 11 is blow molded while being biaxially stretched. In this case, since the pulp molded article constituting the outer container 3 has a certain degree of air permeability, the parison 11 can be blown without providing the outer container with a vent hole for exhausting blow air. . Therefore, when the outer container 3 is made of paperboard (cardboard) having extremely low air permeability, the outer container 3
It is preferable to form a pinhole as a vent hole in any part of the above, for example, the bottom 3d or the like which is hardly noticeable to the user.

Further, when the stretching blow is continued, FIG.
As shown in (2), the inner container 2 having a shape corresponding to the inner shape of the outer container 3 is formed, and the inner surface of the outer container 3 is tightly covered with the inner container 2. As described above, since the outer container 3 is sucked toward the outside of the molding die 10 during the stretching blow, the parison 11 is blown uniformly. As a result, the inner container 2 formed by the stretch blow of the parison 11 closely adheres along the inner surface shape of the outer container 3 without any gap.

The inner container 2 formed by the blow molding of the parison 11 is gradually cooled and thermally contracted. In this case, by controlling the degree of cooling of the inner container 2,
This heat shrinkage is increased, and the flange 4
The shoulder portion 2c (see FIG. 2) is contracted in the direction indicated by arrows A and A 'in FIG. 2, that is, the direction in which the flange portion 4 and the shoulder portion 2c approach each other. 2c, the upright neck 3a of the outer container 3 is held. As a result, the inner container 2 and the outer container 3 are firmly fixed. In particular, as described above, as shown in FIG.
By performing blow molding such that the space 5 is formed between the outer container 3 and the outer container 3, the space 5 acts as a heat insulating portion, and the flange portion 4 and the shoulder portion 2c move in the directions A and A 'in the directions A and A'. The degree of shrinkage is greater and a greater fixing force is generated.

When the inner container 2 has sufficiently adhered to the inner surface of the outer container 3 and the inner container 2 has sufficiently cooled, the blowing of air is stopped, and the molding die 10 is opened. Then, the target composite container is taken out.

The composite container according to the embodiment of the second invention (FIG. 3)
The preferable manufacturing method of the composite container shown in FIG. 4 is also the same as the manufacturing method shown in FIG. That is, the outer container 3 having a predetermined shape of the outer container protrusion 3e formed in the body 3b toward the inside of the container.
Is loaded into a molding die, a bottomed parison heated to a predetermined temperature is inserted into the outer container 3, and then the parison is stretch blow-molded to have a shape corresponding to the inner shape of the outer container 3. Inner container 2 is formed in close contact with the inner surface of the outer container 3. Next, by controlling the degree of cooling of the formed inner container 2, the opposed rising portions 2f, 2f (see FIG. 3) of the inner container convex portion 2e are contracted in a direction approaching each other, and the rising portion is controlled. The outer container projection 3e is sandwiched between 2f and 2f. As a result, the inner container 2 and the outer container 3
Is firmly fixed.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment of the first invention, the upright opening neck 3a of the outer container 3 is clamped / fixed by the flange 4 and the shoulder 2c of the inner container 2 over the entire circumference of the container. It is not limited to this and may be partial.

In the first embodiment of the present invention, the space 5 is formed between the inner container 2 and the outer container 3, but the outer container is formed by the flange portion 4 and the shoulder 2c of the inner container 2. The space 5 may not be formed, or may be partial, as long as the upright neck 3a of the 3 is sufficiently clamped and fixed.

In the above-described embodiment of the second invention, the positions and shapes of the inner container convex portion 2e and the outer container convex portion 3e formed on the inner container 2 and the outer container 3 are determined by the shape and use of the container. Can be changed as appropriate. Further, the inner container convex portion 2e and the outer container convex portion 3e may be formed at other positions, for example, at the bottom portion, in addition to the body portion of the inner container 2 and the outer container 3.

In the first and second embodiments of the present invention, the composite container has a cylindrical bottle shape. Alternatively, for example, an elliptical or flat bottle shape, or a box-shaped carton may be used instead. Other shapes, such as shapes, are also possible.

Further, the inner container and the outer container may be fixed by combining the first invention and the second invention. That is, a resin inner container having an upper opened mouth and neck, a body, a shoulder connecting the mouth and neck and the body, and a bottom, and an opening of the mouth and neck of the inner container. And an outer container made of pulp having an opening of a large size and an upright opening neck in the height direction of the container. A convex portion having a predetermined shape is formed toward the outer container, and the outer container has a shape capable of fitting with the convex portion at a position corresponding to the convex portion in the outer container under the state where the inner container is housed. The convex portion is formed toward the inside of the container, and the inner container is inserted into the outer container in a state where the mouth-neck portion of the inner container extends outward from the standing mouth-neck portion of the outer container. The upright mouth and neck portion of the outer container is accommodated in the inner container, and a flange formed on an outer surface of the mouth and neck portion of the inner container is provided. The convex portion formed on the inner container and the convex portion formed on the outer container are fitted together with the inner portion and the shoulder portion of the inner container. It may be a composite container in which the outer container is fixed.

The thicknesses of the inner container and the outer container shown in FIGS. 1 to 4 are shown for the sake of convenience, and do not show the relative relationship between the actual thicknesses.

[0041]

According to the composite container of the present invention, the inner and outer containers are mechanically and firmly fixed without adhesion or fusion. Also,
According to the composite container of the present invention, separation and disposal of the inner and outer containers are facilitated.

[Brief description of the drawings]

FIG. 1 is a partially broken front view showing an embodiment of a composite container according to the first invention.

FIG. 2 is an enlarged sectional view of a main part of the composite container shown in FIG.

FIG. 3 is a partially cutaway front view (corresponding to FIG. 1) showing an embodiment of the composite container of the second invention.

FIG. 4 is a process chart showing a preferred method for producing the composite container shown in FIGS. 1 and 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Composite container 1b Body 1e Convex part 2 Inner container 2a Mouth and neck part 2b Body 2c Shoulder part 2d Bottom part 2e Inner container convex part 2f Standing part 3 Outer container 3a Standing mouth neck part 3b Body 3c Shoulder part 3d Bottom part 3e Inner container convex part 4 Flange part 5 Space

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Takemura 2606 Kabane-cho, Akaga-cho, Haga-gun, Tochigi Kato Co., Ltd. (72) Inventor Tokito Sono 2606 Kabane-cho, Akaga-bane, Haga-gun, Tochigi Kao Research In-house F-term (reference) 3E033 AA01 BA10 BA15 BA16 BA18 BA21 BB08 CA03 CA06 CA20 FA03 GA02 3E067 AA03 BA03B BA03C BB01C BB13C BB14B BB15B BB16B EE59 FA04 FC01

Claims (6)

[Claims] 1. A resin inner container having an upper opened mouth and neck, a torso, a shoulder connecting the mouth and neck to the body, and a bottom, and a mouth and neck of the inner container A pulp outer container having an opening having a size larger than the opening of the pulp and having an upright neck portion standing upright in the height direction of the container, wherein the inner container is a container of the outer container. The mouth and neck of the inner container is accommodated in the outer container in a state where the mouth and neck of the inner container extends outward from the standing mouth and neck, and the standing mouth and neck of the outer container are the mouth of the inner container. A composite container in which the inner container and the outer container are fixed by being sandwiched between a flange formed on an outer surface of a neck and the shoulder of the inner container. 2. The composite container according to claim 1, wherein a thickness of a portion of the inner container facing the upright neck portion is larger than a thickness of the body portion of the inner container. 3. A space defined between the inner container and the outer container, the neck portion of the outer container, the flange portion of the inner container, and the shoulder portion of the inner container. The composite container according to claim 1, wherein: 4. A composite container comprising a pulp outer container and a resin inner container housed inside the outer container, wherein the inner container has a body portion having a predetermined shape facing the inside of the container. A convex part having a shape is formed, and the outer container has a convex part capable of fitting with the convex part at a position corresponding to the convex part in the outer container under the state where the inner container is housed. The convex portion formed on the inner container and the convex portion formed on the outer container are fitted toward the inner side of the container, and the inner container and the outer container are fixed. Composite container. 5. The method for manufacturing a composite container according to claim 1, wherein the bottomed parison having a flange portion on an outer surface near an opening, wherein the lower surface of the flange portion is the upright neck portion of the outer container. After being inserted into the outer container through the upright mouth and neck so as to be in contact with the upper end surface of the outer container, the parison is blow-molded to form the inner container having a shape corresponding to the inner shape of the outer container, Next, a method of manufacturing a composite container in which the inner container is cooled and contracted so that the upright neck portion of the outer container is sandwiched between the flange portion and the shoulder portion of the inner container. 6. The method for manufacturing a composite container according to claim 4, wherein the bottomed parison is inserted into the outer container having a convex portion having a predetermined shape formed in a body toward the inside of the container. Blow molding the parison to form the inner container having a shape corresponding to the inner shape of the outer container, and then cooling and shrinking the inner container to blow-mold the convex portion of the outer container. The method for producing a composite container sandwiched by the convex portions formed on the inner container according to the above.