JP2021024199A - Multiplex bottle manufacturing method and preform for multiplex bottle - Google Patents

Abstract

To provide a multiplex bottle manufacturing method for manufacturing a multiplex bottle made of polyester resin, in which an inner container body is hard to be peeled from an outer shell bottle at a bottom part, and the inner container body is easy to be peeled from the outer shell bottle at a part other than the bottom part.SOLUTION: A multiplex bottle manufacturing method includes: an arrangement step in which an inner preform 51 forming an inner container body 3 is inserted into an outer preform 50 forming an outer shell bottle 2 and mold release agent is interposed between the outer preform 50 and the inner preform 51; and a molding step in which the outer preform 50 and the inner preform 51 are blow-molded to form a multiplex bottle 1. In the arrangement step, a step part 50e, an inner peripheral surface of the outer preform 50 and an outer peripheral surface of the inner preform 51 form a gap part 6 for interposing the mold release agent.SELECTED DRAWING: Figure 4

Description

The present invention manufactures a multiple bottle made of synthetic resin, which comprises an outer shell bottle made of polyester resin and an inner container body made of polyester resin which is arranged inside the outer shell bottle and can be deformed by reducing the volume. The present invention relates to a method for producing multiple bottles and a preform for multiple bottles.

Conventionally, an inner container body that is deformed so as to reduce the volume as the contents decrease (hereinafter, may be referred to as "volume reduction deformation") is provided inside the outer shell bottle that can return to the original shape with respect to the external pressure. There are known multiple bottles made of synthetic resin that are arranged and the outside air is introduced between the outer shell bottle and the inner container body.

This multiple bottle is usually used by attaching a pouring cap equipped with a check valve to the mouth, and when the body of the outer shell bottle is pressed, the outer shell bottle is deformed by the pressing and the inner container body. Is reduced in volume and deformed, and the contents contained in the inner container are poured out. On the other hand, when the pressure is released, outside air is introduced between the outer shell bottle and the inner container body, and the outer shell bottle returns to its original shape.

On the other hand, the inner container body is maintained in a volume-reduced and deformed state in which the invasion of outside air is blocked. Thereby, according to this multiple bottle, it is possible to prevent the contents contained in the inner container from being denatured due to oxidation or the like.

As a multiple bottle of this type, a bottle in which an outer shell bottle and an inner container body are formed by using a soft polyethylene resin that is easily deformed in volume reduction is known (see, for example, Patent Document 1).

By the way, a container made of polyester resin (for example, made of polyethylene terephthalate resin) is superior in transparency and retention of flavor of the contained contents as compared with a container made of polyethylene resin. Therefore, there is a method of forming an outer shell bottle and an inner container body by using a polyester resin instead of the polyethylene resin in the multiple bottles as described in Patent Document 1 (see, for example, Patent Document 2).

However, when the multiple bottles are formed by blow molding, when the outer shell bottle and the inner container body are formed using polyester resin, the outer shell bottle and the inner container body are separated from each other as compared with the case where the outer shell bottle and the inner container body are formed using polyethylene resin. Separability is reduced, the inner container body sticks to the outer shell bottle and is difficult to peel off, it is difficult for air to enter between the outer shell bottle and the inner container body, and the inner container body may be less likely to be volume-reduced and deformed. There is.

Therefore, in order to improve the peeling separation property, a mold release agent is interposed between the inner preform forming the inner container body and the outer preform forming the outer shell bottle in the stage before the blow molding. There is a method (see, for example, Patent Document 3).

JP 2013-245010 Japanese Unexamined Patent Publication No. 2017-128383 Japanese Unexamined Patent Publication No. 2017-186059

However, if the release agent penetrates into the bottom portion of the outer preform and the inner preform multiple bottles, the bottom portion of the inner container body is likely to be peeled off even at the bottom of the formed multiple bottles. Will end up.

Then, when the bottom portion of the inner container body is peeled off at the bottom portion, particularly at the inner portion (that is, the bottle axis side) of the ground contact portion at the bottom of the bottle, the inner container body is pressed when the body portion of the outer shell bottle is pressed. When the volume is reduced and deformed, the bottom of the inner container is pulled toward the bottle mouth and the inner container is deformed so as to have a predetermined shape (for example, a shape reduced only in the radial direction). There was a risk that it could not be done. As a result, there is a risk that all the contents cannot be completely poured out from the inner container.

The present invention has been made in view of the above points, and the inner container body is difficult to peel off from the outer shell bottle at the bottom, particularly the inner part of the bottle grounding portion, and the inner container body is peeled off from the outer shell bottle except at the bottom. It is an object of the present invention to provide a method for producing a multiple bottle made of polyester resin, which is easy to use, and a preform for multiple bottles for producing a multiple bottle made of polyester resin.

The method for producing multiple bottles of the present invention
An outer shell bottle made of polyester resin and an inner container body made of polyester resin which is arranged inside the outer shell bottle and is deformable by reducing the volume are provided.
The outer shell bottle has an outer shell portion and an outer shell bottle main body connected to the outer mouth portion.
The inner container body includes an inner mouth portion arranged on the inner peripheral side of the outer mouth portion, and an inner container body body that is connected to the inner mouth portion and has a shape that follows the inner surface shape of the outer shell bottle body. Have,
A passage for introducing a fluid is formed between the outer shell portion and the inner mouth portion and between the outer shell bottle body and the inner container body.
A ground contact portion is formed on the bottom of the outer shell bottle body.
It is a method for manufacturing a multiple bottle for manufacturing a polyester resin multiple bottle in which the bottom portion of the inner container body is in close contact with the inner surface inside the ground contact portion.
Inside the bottomed tubular outer preform forming the outer shell bottle, the bottomed tubular inner preform forming the inner container body is arranged, and the outer preform and the inner preform are combined. An arrangement step in which a mold release agent that promotes separation between the outer shell bottle and the inner container body is interposed between the two.
The outer preform and the inner preform are arranged inside a mold and blow-molded to form a multiple bottle made of polyester resin.
At least one of the outer preform and the inner preform is the distance between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform in the vicinity of the portion where the ground contact portion is formed after the blow molding in the molding step. Has a stepped portion with a narrowed shape
The stepped portion, the inner peripheral surface of the outer preform, and the outer peripheral surface of the inner preform form a gap portion in which the mold release agent is interposed on the side of the stepped portion that forms the passage. It is characterized by being.

As described above, in the multiple bottle manufacturing method of the present invention, a mold release agent is interposed between the outer preform and the inner preform, and then blow molding is performed to form the multiple bottle. As a result, in the formed multiple bottles, the release agent is interposed between the outer shell bottle formed from the outer preform and the inner container body formed from the inner preform, so that a ground contact portion is formed. Except for the inner part from the part, the inner container body is easily peeled off from the outer shell bottle.

Here, in the arranging step of the method for producing the multiple bottles, a gap portion is formed as a space for interposing the release agent. The gap portion is formed by a step portion, an inner peripheral surface of the outer preform, and an outer peripheral surface of the inner preform.

Here, the stepped portion forming the gap portion has a shape that narrows the distance between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform in the vicinity of the portion where the ground contact portion is formed after blow molding in the molding process. There is.

Therefore, this stepped portion prevents the mold release agent from invading from the gap portion to the portion inside the ground contact portion after blow molding in the molding process. That is, the mold release agent interposed in the void portion formed by using the step portion is less likely to penetrate into the inner portion of the bottom portion than the ground contact portion in the molding process.

Therefore, according to the method for manufacturing a multi-bottle of the present invention, the inner container body is easily peeled off from the outer shell bottle by the release agent in the portion of the bottom portion outside the ground contact portion, and the ground contact portion in the bottom portion. Since the release agent is prevented from entering the inner portion, it is possible to manufacture a multiple bottle made of polyester resin in which the bottom portion of the inner container body is not easily peeled off from the outer shell bottle.

Further, in the multiple bottle manufacturing method of the present invention,
The step portion may be formed in a circumferential shape on the inner peripheral surface of the outer preform.

In the method for producing multiple bottles of the present invention,
In the arrangement step, the distance between the step portion and the surface facing the step portion is preferably 1.0 mm or less.

With this configuration, when the preform is heated to the stretching temperature during blow molding, the outer surface of the tubular body of the inner preform and the inner surface of the outer preform come close to each other, and the stepped portion comes into contact with the opposing surfaces. Therefore, even if the release agent becomes easy to flow due to the heating, it is possible to prevent the release agent from entering between the bottom of the outer preform and the bottom of the inner preform (and thus the bottom of the multiple bottle). it can.

Further, since the step portion and the surface facing the step portion are efficiently crimped during the blow molding, it is possible to prevent peeling at the portion inside the grounded portion of the formed multiple bottle after the blow molding.

In the method for producing multiple bottles of the present invention,
In the arrangement step, the distance between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform in the gap is preferably 0.1 mm to 3.0 mm.

When the distance between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform is less than 0.1 mm, a sufficient amount of mold release is performed between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform. It may not be possible to intervene the agent. Therefore, there is a possibility that the peeling distance between the outer shell bottle formed by the outer preform and the inner container formed by the inner preform cannot be sufficiently ensured.

On the other hand, when the interval exceeds 3.0 mm, when the outer preform and the inner preform are heated to a predetermined stretching temperature, the temperature difference between the outer preform and the inner preform becomes large, and the outer preform becomes large. It may be difficult to blow-mold the reform and the inner preform at the same time.

Therefore, by setting the interval to 0.1 mm to 3.0 mm in this way, it is possible to facilitate blow molding of the outer preform and the inner preform at the same time while ensuring sufficient peeling separation.

The preform for multiple bottles of the present invention
A bottomed tubular polyester resin outer preform that forms an outer shell bottle, and a bottomed tubular polyester that is placed inside the outer preform and forms a deformable inner container body with reduced volume. Equipped with a resin inner preform,
The outer shell bottle having a grounding portion formed at the bottom by blow molding and the inner container body having a shape along the inner surface of the outer shell bottle are provided, and the bottom portion of the inner container body is provided on the inner inner surface of the grounding portion. It is a preform for multiple bottles for manufacturing multiple bottles made of polyester resin with the outer surface of the bottle in close contact.
The outer preform has a stepped portion having a shape in which the distance between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform is narrowed in the vicinity of the portion where the ground contact portion is formed after the blow molding. ,
The stepped portion, the inner peripheral surface of the outer preform, and the outer peripheral surface of the inner preform form a gap portion having the stepped portion as the bottom.
It is characterized in that a mold release agent that promotes separation between the outer shell bottle and the inner container body can be interposed in the gap portion.

Further, in the preform for multiple bottles of the present invention,
It is preferable that the gap portion prevents the release agent from entering the portion inside the ground contact portion after the blow molding by the step portion.

The perspective view which shows the structure of the multiple bottle which concerns on embodiment. FIG. 2 is a sectional view taken along line II-II of the multiple bottle of FIG. FIG. 3 is a cross-sectional view of a preform for a multiple bottle of the multiple bottle of FIG. An enlarged view of a main part of the preform for multiple bottles of FIG. FIG. 5A is a cross-sectional view schematically showing a manufacturing method of the multiple bottle of FIG. 1, FIG. 5A is a state in which a preform for multiple bottles is attached to a mold, FIG. 5B is a state during blow molding, and FIG. 5C is a state after blow molding. Indicates the state of.

Hereinafter, the multiple bottle 1 which is a polyester resin multiple bottle according to the present embodiment and a method for manufacturing the multiple bottle 1 will be described with reference to the drawings.

First, the multiple bottle 1 will be described with reference to FIGS. 1 and 2.

As shown in FIGS. 1 and 2, the multiple bottle 1 is arranged inside the outer shell bottle 2 and the outer shell bottle 2 which can return to the original shape with respect to the external pressure, and the volume is reduced as the contents decrease. It is provided with an inner container body 3 that is deformed in this way. In this embodiment,

The outer shell bottle 2 and the inner container 3 use polyethylene terephthalate resin as a suitable resin, but the resin is not limited thereto, and polyester resins such as polybutylene terephthalate resin, polyethylene naphthalate resin, polylactic acid resin, and polyfuranoate resin are used. May be used alone or in combination.

The outer shell bottle 2 has a cylindrical outer mouth portion 20, a shoulder portion 21 connected to the outer mouth portion 20, a cylindrical body portion 22 connected to the shoulder portion 21, and a body portion 22. It is provided with a lower body portion 23 which is continuously provided in the above. In the outer shell bottle 2, the shoulder portion 21, the body portion 22, and the lower body portion 23 form a bottomed tubular outer shell bottle main body 24.

The outer opening portion 20 has a male screw portion 20a on the outer peripheral surface and a support ring 20b provided below the male screw portion 20a. A female screw portion formed on the inner peripheral surface of a cap with a check valve (not shown) is screwed into the male screw portion 20a. As a result, a cap with a check valve is attached to the outer port portion 20.

As a whole, the shoulder portion 21 expands in diameter from the upper end portion (that is, the portion that is continuously provided to the outer opening portion 20) to the lower end portion (that is, the portion that is continuously provided to the body portion 22). It is formed so that it gradually becomes thinner.

The upper portion of the shoulder portion 21 is formed in a substantially quadrangular pyramid shape whose diameter gradually increases downward. The lower portion of the shoulder portion 21 is formed so that the corners of the square pyramid become smooth while gradually increasing the diameter toward the lower side. Therefore, the lower portion thereof has a cylindrical shape at the lower end portion (that is, the portion continuously provided to the body portion 22).

The body portion 22 is configured so that the cross section orthogonal to the central axis extending in the vertical direction is substantially circular. As a result, the body portion 22 can be deformed by pressing against its central axis from any direction.

The wall thickness of the body portion 22 is set in the range of 0.25 to 0.40 mm, preferably 0.25 to 0.35 mm. When the wall thickness is set to such a thickness, the outer shell bottle 2 can be smoothly deformed by the pressing force of the hand, and when the pressing force is released, the outer shell bottle 2 can be smoothly restored to its original shape, which is an excellent squeeze property. it can.

The body portion 22 is connected to the ground contact portion 23b via a tubular body portion lower portion 23.

The lower portion of the tubular portion of the lower body portion 23 is formed in a substantially quadrangular pyramid shape whose diameter gradually increases upward. The upper portion of the tubular portion is formed so that the corners of the square pyramid become smooth while gradually increasing the diameter upward. Therefore, the upper portion thereof has a cylindrical shape at the upper end portion, that is, the portion continuously provided to the body portion 22).

Further, the lower portion 23 of the body portion is provided with a bottom portion 23a that is connected to the annular ground contact portion 23b and bulges in a multi-step shape inside the portion 23b.

The bottom portion 23a has a shape in which square pyramidal recesses are stacked in three stages. The outer shell bottle 2 is imparted with independence by providing the bottom portion 23a.

In the upper portion of the shoulder portion 21 and the lower portion of the tubular portion of the lower body portion 23, the horizontal cross section orthogonal to the central axis is quadrangular. The ridgeline of the shoulder portion 21 is located on an extension of the ridgeline of the tubular portion of the lower portion 23 of the body portion.

As shown in FIG. 2, the inner container body 3 is connected to the cylindrical inner mouth portion 30 arranged on the inner peripheral side of the outer mouth portion 20 and the inner mouth portion 30, and is connected to the outer shell bottle main body 24. It is provided with an inner container body 31 having a shape that conforms to the inner surface shape of the above.

The inner opening portion 30 has a tubular extending portion 30a extending upward from the upper end of the outer opening portion 20 at the upper end portion thereof, and the inner opening portion 30 projecting radially outward from the peripheral edge of the upper end portion of the extending portion 30a. It has a collar portion 30b. The inner opening portion 30 is locked to the upper end edge of the outer opening portion 20 by the flange portion 30b.

Further, the inner opening portion 30 is formed with a plurality of vertical grooves 30c extending in the vertical direction along the central axis of the inner opening portion 30 at intervals in the circumferential direction on the outer peripheral surface thereof. The vertical groove 30c extends to the lower end of the inner opening portion 30. The number of vertical grooves 30c may be only one.

Further, in the inner opening portion 30, a lateral groove 30d extending in the radial direction of the inner opening portion 30 is formed on the lower surface of the flange portion 30b. The inner peripheral portion of the horizontal groove 30d is continuously provided at the upper end of the vertical groove 30c. That is, the same number of horizontal grooves 30d as those of the vertical grooves 30c are provided. Further, the outer peripheral portion of the lateral groove 30d is open to the outside at the outer peripheral edge of the flange portion 30b.

A passage 4 is formed between the outer opening portion 20 and the inner opening portion 30 by the vertical groove 30c and the horizontal groove 30d. The passage 4 introduces a fluid between the outer shell bottle body 24 and the inner container body 31. A space is formed between the fluid introduced in this way and the release agent described later.

The inner container body 31 is formed to be thinner than the outer shell bottle body 24. Specifically, the wall thickness of the inner container body 31 is set in the range of 0.03 to 0.20 mm, preferably 0.05 to 0.15 mm. As a result, the inner container body 31 can be easily reduced in volume and deformed in response to the deformation of the outer shell bottle body 24 due to pressing.

The multiple bottle 1 configured in this way is used by attaching a check valve-equipped pouring cap to the outer port 20 of the outer shell bottle 2. When pouring out the contents contained in the inner container body 3, the user first tilts the outer mouth portion 20 and the inner mouth portion 30 so as to face downward. Then, when the user grips and presses the body 22 of the outer shell bottle 2, the inner container body 31 is reduced in volume and deformed. As a result, the contents are extruded from the inner container body 3 main body and are ejected from the inner mouth portion 30.

When the pressure on the body 22 of the outer shell bottle 2 is released after the contents are poured out, the shoulder portion 21 and the contents are formed from the vertical groove 30c forming the passage 4 between the outer shell bottle 2 and the inner container body 31. Outside air is introduced between the body and the body 31. The outer shell bottle 2 returns to its original shape by the restoring force. On the other hand, the inner container body 31 is maintained in a state of being reduced in volume and deformed by preventing the intrusion of outside air by a check valve provided separately.

At this time, since the contents are concentrated on the inner mouth portion 30 side due to gravity, it corresponds to the portion sandwiched between the ridges of the tubular portion of the lower body portion 23 of the outer shell bottle 2 of the inner container body 31. A valley fold portion inward of the inner container body 31 is formed on the side surface portion. Then, the inner container body 31 is peeled off from the outer shell bottle 2 starting from that portion, and is immersed inward along the valley fold portion so as to follow the length direction of the outer shell bottle 2. The valley folds and deforms.

Therefore, in the multiple bottle 1, the contents are reduced when the pressing of the body 22 of the outer shell bottle 2 and the release of the pressing are repeated in order to eject the contents contained in the inner container body 31. At the same time, the valley bending deformation of the inner container body 31 progresses, and the volume reduction deformation such that the inner container body 31 is folded progresses.

By the way, the multiple bottle 1 is provided with a bottom portion 23a on the bottom surface thereof. Since the release agent is prevented from entering the inner surface of the bottom portion 23a by the step portion 50e described later even during blow molding, the inner container body 31 is in close contact with the inner surface by heat pressure bonding during blow molding.

Further, the bottom portion 23a is composed of a plurality of laminated quadrangular pyramid-shaped recesses. Therefore, in the vicinity of the bottom 23a, it is difficult for outside air to enter between the outer shell bottle 2 and the inner container body 31, and the inner container body 31 is less likely to be peeled off from the outer shell bottle.

Therefore, in the multiple bottle 1, by pouring out the contents contained in the inner container body 31, the inner container body 31 is deformed in a valley along the length direction of the outer shell bottle 2. Even in this case, the inner container body 3 does not peel off from the outer shell bottle 2 at the bottom portion 23a of the inner portion of the ground contact portion 23b of the outer shell bottle 2.

As a result, in the multiple bottle 1, when the contents are poured out from the inner container body 31, the inner container 3 does not peel off from the bottom 23a of the outer shell bottle 2 in the length direction of the outer shell bottle 2. It bends and deforms along the valley. That is, the deformation of the inner container body 31 is restricted so as to be a deformation that does not easily hinder the movement of the contents.

Therefore, in the multiple bottle 1, when the inner container body 31 is volume-reduced and deformed, the deformed inner container body 31 hinders the movement of the contents, and the contents remain in the inner container body 31. It is possible to suppress this.

Next, with reference to FIGS. 3 and 4, a polyester resin multi-bottle preform (hereinafter, referred to as “preform 5”) for forming the multi-bottle 1 by blow molding will be described.

The preform 5 includes an outer preform 50 that forms the outer shell bottle 2 and an inner preform 51 that is arranged inside the outer preform 50 and forms the inner container body 3. The multiple bottle 1 is manufactured by biaxially stretching blow molding the preform 5 at a predetermined stretching temperature. The predetermined stretching temperature is set based on the type, wall thickness, size, etc. of the resin used for the outer preform 50 and the inner preform 51.

Since the outer preform 50 and the inner preform 51 are for forming the outer shell bottle 2 and the inner container body 3, they are formed by injection molding using a polyester resin.

The outer preform 50 includes an outer preform opening 50a having the same shape as the outer opening 20 of the outer shell bottle 2, and a cylindrical outer preform body 50b connected below the outer preform opening 50a. The outer preform bottom 50c is provided with a hemispherical outer preform bottom 50c that closes the lower end opening of the outer preform body 50b. Further, a support ring portion 50d having the same shape as the support ring 20b of the outer shell bottle 2 is provided on the outer peripheral surface of the outer preform opening portion 50a.

The inner preform 51 includes an inner preform opening 51a having the same shape as the inner opening 30 of the inner container body 3 and a cylindrical inner preform body 51b connected below the inner preform opening 51a. It is provided with a hemispherical inner preform bottom portion 51c that closes the lower end opening of the inner preform body portion 51b.

By applying between the outer preform body 50b and the inner preform body 51b to at least one of the inner peripheral surface of the outer preform body 50b and the outer peripheral surface of the inner preform body 51b. A mold release agent is present. As the release agent, for example, liquid paraffin, paraffin that becomes liquid at the stretching temperature, silicon-based compounds, and the like are used.

Here, in the portion above the step portion 50e described later, the distance between the outer preform body portion 50b of the outer preform 50 and the inner preform body portion 51b of the inner preform 51 is 0.1 mm to 3.0 mm. It has become.

When this distance is less than 0.1 mm, a sufficient amount of mold release agent may be interposed between the outer preform body 50b of the outer preform 50 and the inner preform body 51b of the inner preform 51. It may not be possible. Therefore, there is a possibility that the peeling distance between the outer shell bottle 2 formed by the outer preform 50 and the inner container body 3 formed by the inner preform 51 cannot be sufficiently ensured.

On the other hand, when this interval exceeds 3.0 mm, when the outer preform 50 and the inner preform 51 are heated to a predetermined stretching temperature, the temperature difference between the outer preform 50 and the inner preform 51 is large. Therefore, it may be difficult to blow-mold the outer preform 50 and the inner preform 51 at the same time.

By the way, when a mold release agent is interposed between the outer preform body 50b of the outer preform 50 and the inner preform body 51b of the inner preform 51 as described above, for example, during blow molding. If the fluidity of the release agent is increased by heating, the release agent may infiltrate into a portion other than the intended portion. Specifically, the release agent may penetrate into the bottom portion 23a of the multiple bottle 1.

If the release agent penetrates into the portion of the multiple bottle 1 that becomes the bottom 23a in this way, peeling is likely to occur even at the bottom 23a of the formed multiple bottle 1. Then, when the bottom portion 23a is peeled off, the inner container body 3 has a predetermined shape (for example, a shape whose diameter is reduced only in the radial direction) when the body portion 22 of the outer shell bottle 2 is pressed. There was a risk that the volume could not be reduced and deformed. As a result, there is a risk that all the contents cannot be completely poured out from the inner container body 3.

Therefore, as shown in FIG. 4, in the preform 5, a circumferential (annular) step that projects from the inner peripheral surface of the outer preform 50 toward the opposite surface (that is, the outer peripheral surface of the inner preform 51). A portion 50e is provided.

The stepped portion 50e has a shape in which the distance between the inner peripheral surface of the outer preform 50 and the outer peripheral surface of the inner preform 51 is narrowed in the vicinity of the portion where the ground contact portion 23b is formed after blow molding. is there.

Then, the release agent is held by the step portion 50e, the portion of the inner peripheral surface of the outer preform body portion 50b above the step portion 50e, and the outer peripheral surface of the inner preform body portion 51b. The gap portion 6 is formed. The gap 6 defines a tubular space, and before blow molding, the release agent is held inside the space.

The gap portion 6 is formed on the side of the step portion 50e that forms the vertical groove 30c (specifically, the upper side in FIG. 4). That is, the bottom portion of the gap portion 6 is formed by the step portion 50e. Here, the step portion 50e is provided in the vicinity of a portion of the inner peripheral surface of the outer preform 50 that forms the ground contact portion 23b after blow molding.

Therefore, at the time of blow molding and after blow molding, the step portion 50e is on the side (specifically, the bottom portion) of the outer shell bottle 2 from the tubular space which is the gap portion 6 inside the ground contact portion 23b of the outer shell bottle 2. The region where the 23a is formed), that is, the invasion of the release agent into the bottom 23a is prevented.

The step portion 50e is configured to project toward an opposing surface (specifically, an outer peripheral surface of the inner preform body portion 51b). In the preform 5, the distance between the stepped portion 50e and the facing surface is narrower than the distance between the outer preform body portion 50b and the inner preform body portion 51b. Specifically, it is configured to be 1.0 mm or less, preferably 0 mm.

With this configuration, when the preform 5 is heated during blow molding, the inner preform body 51b expands in the radial direction and comes into contact with the opposing stepped portions, and the release agent flows by the heating. Even if it becomes easy to do so, it is possible to prevent the release agent from invading between the outer preform bottom 50c and the inner preform bottom 51c (and by extension, the bottom 23a of the multiple bottle 1).

Further, since the step portion 50e and the surface facing the step portion 50e are efficiently pressure-bonded during blow molding, peeling at a portion inside the grounded portion 23b of the formed multiple bottle 1 can be suppressed after blow molding.

Next, a blow molding apparatus 7 for manufacturing the multiple bottle 1 will be described with reference to FIG.

As shown in FIG. 5, the blow molding apparatus 7 includes a mold 70, a blow nozzle 71, and a stretch rod 72.

The mold 70 includes a molding portion 70a having a shape along the outer shape of the outer peripheral surface of the outer shell bottle body 24 below the outer mouth portion 20 of the outer shell bottle 2, and a support ring for the outer preform opening portion 50a of the outer preform 50. It is provided with a support opening 70b that supports the portion 50d from below. The mold 70 has a split mold structure, and the multiple bottle 1 after molding can be removed by dividing the mold 70 into a left-right side and a bottom side.

The blow nozzle 71 is raised and lowered by an elevating means (not shown), and airtightly contacts the upper end surface of the inner preform opening 51a of the inner preform 51 via the O-ring 71a. A gas passage 71b connected to a high-pressure gas supply means (not shown) is formed in a portion of the blow nozzle 71 on the inner peripheral side of the O-ring. A stretch rod 72 is inserted through the gas passage 71b so as to be movable in the vertical direction.

The stretch rod 72 is advanced during blow molding by an advancing / retreating driving means (not shown). In FIG. 5A showing the initial state of blow molding, the stretch rod 72 protrudes from the tip of the blow nozzle 71, but is retracted when not in use and is housed inside the blow nozzle 71 (upper in the figure). ing.

Next, with reference to FIGS. 3 and 5, a manufacturing method for forming the multiple bottle 1 from the preform 5 by blow molding using the blow molding apparatus 7 will be described. Note that FIG. 5 shows, in order from the left, an initial state (FIG. 5A), a state during blow molding (FIG. 5B), and a state after blow molding is completed (FIG. 5C).

In this manufacturing method, first, as shown in FIG. 3, the inner preform 51 is inserted into the outer preform 50 and placed inside the outer preform 50. At this time, a gap portion 6 (see FIG. 4) is formed between the outer preform 50 and the inner preform 51, and the gap portion 6 is prompted to separate the outer shell bottle 2 and the inner container body 3. Intervene a release agent for the purpose. This step is the placement step in the present invention.

Next, as shown in FIG. 5A, after setting the outer preform 50 (that is, the preform 5) in which the inner preform 51 is arranged inside in the mold 70, the inner preform opening of the inner preform 51 The blow nozzle 71 is connected to the portion 51a. At this time, the preform 5 is heated to a predetermined drawing temperature at which blow molding is possible before being set in the mold 70.

Next, as shown in FIG. 5B, pressurized air is introduced into the inner preform 51 from the gas passage 71b of the blow nozzle 71, and the stretch rod 72 is extended downward.

As a result, first, the inner preform body 51b of the inner preform 51 expands and comes into close contact with the inner surface of the outer preform body 50b of the outer preform 50 in the unexpanded state.

After that, when the stretch rod 72 is extended downward while further introducing pressurized air into the inner preform 51, the outer preform of the outer preform 50 is formed by the inner preform body 51b of the expanded inner preform 51. The body portion 50b is pushed open.

As a result, as shown in FIG. 5C, the outer preform body 50b of the outer preform 50 is molded so as to follow the inner surface shape of the molded portion 70a of the mold 70, and the outer shell bottle main body of the outer shell bottle 2 is formed. 24 is formed. Further, the inner preform body portion 51b of the inner preform 51 is formed so as to follow the inner surface shape of the outer shell bottle main body 24 of the outer shell bottle 2, and the inner container body main body 31 of the inner container body 3 is formed. ..

The process described with reference to FIGS. 5A to 5C is the molding process of the present invention. At the end of this step, the outer surface of the inner container body 31 of the inner container 3 is in close contact with the inner surface of the outer shell bottle body 24 of the outer shell bottle 2.

After these steps are completed, the stretch rod 72 is retracted from the inside of the multiple bottle 1 and the multiple bottle 1 is removed from the mold 70.

As described above, in this multiple bottle manufacturing method, a mold release agent is interposed between the outer preform and the inner preform, and then blow molding is performed to form the multiple bottle. As a result, in the formed multiple bottles, the mold release agent is also interposed between the outer shell bottle formed from the outer preform and the inner container body formed from the inner preform, so that the mold release agent is interposed from the outer shell bottle. The inner container is easy to peel off.

Here, in the arranging step of the method for manufacturing the multiple bottles, the void portion 6 is formed as a space for interposing the release agent. The gap portion 6 is formed by an inner peripheral surface of the outer preform 50 and an outer peripheral surface of the inner preform 51 above the step portion 50e.

Here, the stepped portion 50e forming the gap portion 6 provides a distance between the inner peripheral surface of the outer preform 50 and the outer peripheral surface of the inner preform 51 in the vicinity of the portion where the ground contact portion 23b is formed after blow molding in the molding step. It has a narrowed shape.

Therefore, the stepped portion 50e prevents the mold release agent from invading from the gap portion 6 to the portion side that is on the inner peripheral side of the ground contact portion 23b after blow molding in the molding step. That is, the mold release agent interposed in the gap portion 6 formed by using the step portion 50e is less likely to penetrate into the portion of the formed lower portion 23 of the body portion 23 inside the ground contact portion 23b.

Therefore, according to this multiple bottle manufacturing method, the outer shell bottle or the inner container 3 is easily peeled off by the release agent in the portion of the lower body portion 23 on the outer peripheral side of the ground contact portion 23b. In addition, since the release agent is prevented from entering the portion of the lower portion 23 of the body portion on the inner peripheral side of the ground contact portion 23b, the inner container body 3 is made of synthetic resin which is difficult to peel off from the outer shell bottle 2. Multiple bottles 1 can be manufactured.

Further, in this multiple bottle manufacturing method, the distance between the inner peripheral surface of the outer preform 50 and the outer peripheral surface of the inner preform 51 is 0.1 mm to 3.0 mm. In this configuration, blow molding is performed with the outer preform 50 and the inner preform 51 sufficiently close to each other. As a result, at the time of blow molding, the outer preform 50 and the inner preform 51 are brought into close contact with each other via a mold release agent, and they are integrally stretched.

That is, during blow molding, the inner preform 51 is in contact with and supported by the inner peripheral surface of the outer preform 50 at an early stage of blow molding. As a result, even when a polyester resin having a lower flexibility than the polyethylene resin is used, the inner container body 3 having a thin wall thickness of 0.03 mm to 0.2 mm while suppressing the occurrence of uneven wall thickness and pinholes. Can be manufactured.

Although the illustrated embodiment has been described above, the present invention is not limited to such an embodiment.

For example, in the above embodiment, the step portion 50e is configured as an annular member. However, the step portion of the present invention is not limited to such a configuration, and the shape of the step portion defines a tubular space together with the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform. Any shape may be used as long as it can form a gap portion.

For example, the stepped portion is continuously formed over the entire circumference of the inner peripheral surface of the body portion of the bottomed tubular outer preform or the outer peripheral surface of the body portion of the bottomed tubular inner preform. It may be a ring-shaped one. Further, the shape may be such that it covers the outer peripheral surface of the bottom of the outer preform or the entire outer peripheral surface of the bottom of the inner preform.

Further, for example, the shape of the surface that becomes the bottom of the gap portion of the step portion may be a substantially horizontal flat shape, a tapered shape that is inclined toward the outer peripheral side or the inner peripheral side, or a curved shape. It may be stepped or the like.

Further, in the above embodiment, as a preferred embodiment, the step portion 50e is configured to project from the inner peripheral surface of the outer preform 50 toward the opposite surface. However, the step portion of the present invention is not limited to such a configuration. The step portion may be provided on at least one of the outer preform and the inner preform.

Therefore, for example, the step portion may be provided on the outer peripheral surface of the inner preform, or may be provided on both the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform.

1 ... Multiple bottles, 2 ... Outer shell bottles, 3 ... Inner containers, 4 ... Passages, 5 ... Preforms (preforms for multiple bottles), 6 ... Voids, 7 ... Blow molding equipment, 20 ... Outer mouths, 20a ... male screw part, 20b ... support ring, 21 ... shoulder part, 22 ... body part, 23 ... lower part of body part, 23a ... bottom part, 23b ... grounding part, 24 ... outer shell bottle body, 30 ... inner mouth part, 30a ... extension part, 30b ... flange part, 30c ... vertical groove, 30d ... horizontal groove, 31 ... inner container body body, 50 ... outer preform, 50a ... outer preform mouth part, 50b ... outer preform body part, 50c ... outer preform bottom, 50d ... support ring, 50e ... stepped part, 51 ... inner preform, 51a ... inner preform mouth, 51b ... inner preform body, 51c ... inner preform bottom, 70 ... mold , 70a ... Molded part, 70b ... Support opening, 71 ... Blow nozzle, 71a ... O ring, 71b ... Gas passage, 72 ... Stretch rod.

Claims (6)

An outer shell bottle made of polyester resin and an inner container body made of polyester resin which is arranged inside the outer shell bottle and is deformable by reducing the volume are provided.
The outer shell bottle has an outer shell portion and an outer shell bottle main body connected to the outer mouth portion.
The inner container body includes an inner mouth portion arranged on the inner peripheral side of the outer mouth portion, and an inner container body body that is connected to the inner mouth portion and has a shape that follows the inner surface shape of the outer shell bottle body. Have,
A passage for introducing a fluid is formed between the outer shell portion and the inner mouth portion and between the outer shell bottle body and the inner container body.
A ground contact portion is formed on the bottom of the outer shell bottle body.
It is a method for manufacturing a multiple bottle for manufacturing a polyester resin multiple bottle in which the bottom portion of the inner container body is in close contact with the inner surface inside the ground contact portion.
Inside the bottomed tubular outer preform forming the outer shell bottle, the bottomed tubular inner preform forming the inner container body is arranged, and the outer preform and the inner preform are combined. An arrangement step in which a mold release agent that promotes separation between the outer shell bottle and the inner container body is interposed between the two.
The outer preform and the inner preform are arranged inside a mold and blow-molded to form a multiple bottle made of polyester resin.
At least one of the outer preform and the inner preform is the distance between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform in the vicinity of the portion where the ground contact portion is formed after the blow molding in the molding step. Has a stepped portion with a narrowed shape
The stepped portion, the inner peripheral surface of the outer preform, and the outer peripheral surface of the inner preform form a gap portion in which the mold release agent is interposed on the side of the stepped portion that forms the passage. A multi-bottle manufacturing method characterized by being present. In the multiple bottle manufacturing method according to claim 1,
A method for manufacturing a multiple bottle, wherein the stepped portion is formed in a circumferential shape on the inner peripheral surface of the outer preform. In the multiple bottle manufacturing method according to claim 1 or 2.
A method for manufacturing a multiple bottle, characterized in that, in the arrangement step, the distance between the step portion and the surface facing the step portion is set to 1.0 mm or less. In the multiple bottle manufacturing method according to any one of claims 1 to 3.
A method for producing a multiple bottle, wherein in the arrangement step, the distance between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform in the gap is 0.1 mm to 3.0 mm. A bottomed tubular polyester resin outer preform that forms an outer shell bottle, and a bottomed tubular polyester that is placed inside the outer preform and forms a deformable inner container body with reduced volume. Equipped with a resin inner preform,
The outer shell bottle having a grounding portion formed at the bottom by blow molding and the inner container body having a shape along the inner surface of the outer shell bottle are provided, and the bottom portion of the inner container body is provided on the inner inner surface of the grounding portion. It is a preform for multiple bottles for manufacturing multiple bottles made of polyester resin with the outer surface of the bottle in close contact.
The outer preform has a stepped portion having a shape in which the distance between the inner peripheral surface of the outer preform and the outer peripheral surface of the inner preform is narrowed in the vicinity of the portion where the ground contact portion is formed after the blow molding. ,
The stepped portion, the inner peripheral surface of the outer preform, and the outer peripheral surface of the inner preform form a gap portion having the stepped portion as the bottom.
A preform for multiple bottles, characterized in that a mold release agent that promotes separation between the outer shell bottle and the inner container body can be interposed in the gap portion. In the preform for multiple bottles according to claim 5.
The gap portion is a preform for multiple bottles, characterized in that the step portion prevents the release agent from invading the portion inside the ground contact portion after the blow molding.

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