JP5789555B2 - Double container manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a double container.

2. Description of the Related Art Conventionally, a double container including an inner container in which contents are stored and an outer container in which the inner container is installed is known. This type of double container is manufactured, for example, by stretch blow molding.
As an example of the method, as shown in Patent Document 1, first, a bottomed cylindrical inner preform that is a molded product before blow molding of the inner container and a molded product before blow molding of the outer container are present. After producing the bottom cylindrical outer preforms, the inner preforms are inserted into the outer preforms and overlapped. Next, both preforms are heated to a temperature at which they can be stretched, and then both preforms are stretched and blow-molded while high-pressure air of a predetermined pressure is fed from the opening (gate) of the inner preform. In this way, a double container is manufactured.

  In addition, a double container is also known in which the inner container is deformed and deformed with respect to the outer container for the purpose of reducing the remaining amount of the contents (for example, Patent Document 2).

Japanese Utility Model Publication No. 53-25856 JP 2011-136704 A

By the way, although an inner container and an outer container are formed from resin materials, such as a thermoplastic resin, the material selection is made | formed suitably according to the use of the double container, the kind of contents, etc. in detail. Here, when the material of the inner container and the material of the outer container are different, the inner container may be contracted and deformed more than the outer container at the time of cooling by blow molding. In addition, due to this contraction deformation, outside air may enter between the inner container and the outer container, and the inner container may further contract and deform, for example, withering.
In particular, the tendency was more remarkable as the heat shrinkage rate of the material of the inner container is larger than the heat shrinkage rate of the material of the outer container.

  This invention is made | formed in view of such a situation, Comprising: Even if it forms the inner container and the outer container with a different material, the objective can suppress the shrink deformation of the inner container after shaping | molding. It is to provide a method for manufacturing a double container.

In order to achieve the above object, the present invention provides the following means.
(1) The method for producing a double container according to the present invention has a bottomed cylindrical projection projecting downward from the lower end while accommodating the contents, thereby reducing the contents. An inner container that undergoes volume reduction deformation, and the inner container is internally provided and has a cylindrical introduction cylinder projecting downward from the lower end, and an opening portion of the introduction cylinder is formed with the inner container An outer container into which an outside air is introduced, and a manufacturing method of a double container, wherein the bottomed cylindrical first preform in which the introduction cylinder part is formed, A setting step of setting a second preform formed with a bottomed cylindrical shape made of a material having a thermal contraction rate larger than that of the material forming the first preform, and having the protrusions formed thereon ; and the first and second profiles. A heating step of heating the reform to a temperature at which stretching can be performed, and closing the introduction hole in the first preform. In state, the first, by a blowing process which simultaneously blow molding the second preform to form a double container, with a time of the setting step, inserting the protrusion into the introduction tube portion, The introduction hole is closed using the second preform, and the projection is fitted into the introduction cylinder by pushing the projection into the introduction cylinder during the blowing step. To do.

According to the method for manufacturing a double container according to the present invention, a double container is formed by simultaneously blow-molding the first preform and the second preform with the introduction hole in the first preform closed. Even if the inner container tends to shrink more than the outer container in the process of lowering the temperature of the double container after blow molding, the pressure between the inner container and the outer container caused by the shrinkage deformation is maintained at a negative pressure. Is done. Therefore, shrinkage deformation of the inner container can be suppressed. Therefore, for example, it is possible to prevent problems such as the inner container largely peeling from the outer container before use, and the quality as a double container can be improved.
Further, since the introduction hole in the first preform can be closed using the second preform set in the first preform without using a separate means for closing, the setting process to the blowing process. It is possible to perform an efficient work over a period of time. Moreover, after a blow process, it is easy to release a double container from a shaping die quickly, and productivity can be improved.

(2) In the method for manufacturing a double container according to the present invention, it is preferable that the introduction hole is closed when the first and second preforms are stretched in the axial direction by a stretching rod in the blowing step.

  In this case, the drawing rod is urged from the inside to the outside, and the closed state of the introduction hole can be reliably maintained.

(3) In the method for manufacturing a double container according to the present invention, a plug is disposed in the introduction hole in the first preform before the setting step, and the closed state of the introduction hole is maintained by the plug. It is preferable to do.

  In this case, the introduction hole can be reliably closed without being affected by the shapes of the first and second preforms.

  According to the present invention, even when the inner container and the outer container are formed of different materials, a double container that can suppress shrinkage deformation of the inner container after molding can be obtained.

It is a half longitudinal cross-sectional view of the double container manufactured with the manufacturing method which concerns on this invention. It is a semi-longitudinal sectional view of the first preform before becoming the outer container shown in FIG. It is a half longitudinal cross-sectional view of the 2nd preform before becoming an inner container shown in FIG. It is a figure which shows the state which forms the double container by blow-molding both preforms after setting a 2nd preform in a 1st preform. It is sectional drawing which shows the state which set the 2nd preform, after putting the stopper in the introduction cylinder part of the 1st preform.

Hereinafter, an embodiment of a method for producing a double container according to the present invention will be described with reference to the drawings. In each drawing used in the following description, the scale is appropriately changed to make each member a recognizable size.
(Configuration of double container)

First, the double container will be described.
As shown in FIG. 1, the double container 1 contains a non-illustrated content, a flexible inner container 2 that is reduced in volume as the contents are reduced, and the inner container 2. The outer container 3 is a double container in which the inner container 2 is stacked so as to be removable from the inner surface of the outer container 3.

The inner container 2 and the outer container 3 are arranged in a state in which their central axes are located on a common axis. In the present embodiment, this common axis is referred to as the container axis O, the direction along the container axis O is the vertical direction, the mouth 10 side along the vertical direction is the upper side, and the opposite side is the lower side. A direction perpendicular to the container axis O is referred to as a radial direction.
In addition, the double container 1 of this embodiment is produced by the stretch blow molding by the manufacturing method mentioned later, and the inner container 2 and the outer container 3 are formed with the resin material of a different material. For example, the outer container 3 is formed of PET (polyethylene terephthalate), and the inner container 2 is formed of PP (polypropylene) having a thermal contraction rate higher than that of PET.

  The mouth portion 10 of the double container 1 is configured such that the mouth portion 11 of the inner container 2 and the mouth portion 12 of the outer container 3 are laminated. At this time, an annular folded portion 11a protruding outward in the radial direction is formed at the upper end portion of the mouth portion 11 of the inner container 2, and the mouth portion 12 of the outer container 3 is utilized using this folded portion 11a. The open end is closed from above. Therefore, the mouth portion 12 of the outer container 3 is closed by the inner container 2.

  Further, a cylindrical introduction tube portion 15 projects downward from the lower end portion of the outer container 3. The opening portion of the introduction cylinder portion 15 functions as an introduction hole 15 a for introducing outside air between the outer container 3 and the inner container 2. Note that a bottomed cylindrical projection 16 projects downward from the lower end of the inner container 2 and is inserted into the introduction cylinder 15 to close the introduction hole 15a.

(Operation of double container)
The double container 1 configured as described above can be pushed down, for example, at the mouth portion 10 of the double container 1, and the discharge port for sucking up and discharging the contents in the inner container 2 in accordance with the pushing operation. A pressing head (not shown) formed is attached, and the inner container 2 is deformed and deformed as the contents are reduced by the pressing operation, so that the inner container 2 is detached from the outer container 3 and the space between the two containers 2 and 3 is reduced. Is reduced in pressure, and outside air flows into this space from the introduction hole 15a.
Alternatively, a pressure device (not shown) that supplies outside air between the inner container 2 and the outer container 3 through the introduction hole 15 a is attached to the introduction cylinder portion 15 of the outer container 3, and the space between the inner container 2 and the outer container 3 is installed. The contents are discharged by opening the discharge port disposed in the mouth portion 10 of the double container 1 in a state where the pressure of the double container 1 is increased.

Therefore, according to the double container 1, the inner container 2 is reduced in volume due to a decrease in internal pressure as the contents are discharged. However, outside air is introduced between the inner container 2 and the outer container 3 through the introduction hole 15 a. Since it flows in, the outer container 3 maintains its original state without being deformed.
Therefore, it is possible to maintain the state of the outer container 3 as it is, while the inner container 2 is detached from the outer container 3 and reduced in volume.

(Manufacturing method of double container)
Next, the manufacturing method of the double container 1 mentioned above is demonstrated.
First, as shown in FIGS. 2 and 3, a first preform 3A that is a molded product of the outer container 3 before blow molding and a second preform 2A that is a molded product of the inner container 2 before blow molding are respectively prepared. prepare.
The first preform 3A is produced by injecting a molten resin material (PET) into a cavity of a molding die (not shown) and solidifying the resin material. The first preform 3A thus injection-molded is formed into a bottomed cylindrical shape having a mouth portion 12, and an introduction cylinder portion 15 is projected from the lower end portion thereof.

  Note that the second preform 2A is also formed into a bottomed cylindrical shape having the mouth portion 11 by injection molding as in the case of the first preform 3A, and a projecting portion 16 projects from the lower end portion thereof. The second preform 2A is made of a resin material (PP) different from the first preform 3A.

  Next, as shown in FIG. 4, a setting process is performed in which the second preform 2A is inserted and set in the first preform 3A. At this time, the mouth portion 12 of the first preform 3A is closed by the folded portion 11a of the mouth portion 11 of the second preform 2A. Further, the protrusion 16 of the second preform 2A is inserted into the introduction cylinder portion 15 of the first preform 3A, whereby the introduction hole 15a of the introduction cylinder portion 15 is closed.

Next, a heating step of heating the combined first preform 3A and second preform 2A to a temperature at which stretching can be performed is performed. As temperature in that case, it is about 100-130 degreeC, for example. And after this heating is complete | finished, both preform 2A, 3A is set in the metal mold | die for blow molding which is not shown in figure.
At this time, the blow molding die is also heated to about 50 to 80 ° C., for example.

Next, the first preform 3A and the second preform 2A are simultaneously stretch-blow molded to perform a blowing process for forming the double container 1 as shown in FIG.
In this step, high-pressure air of a predetermined pressure (for example, 2 to 3 MPa) is supplied into the second preform 2A from the mouth 11 side of the second preform 2A, and a drawing rod (not shown) is put into the second preform 2A. By projecting, both the preforms 2A and 3A are stretch blow molded.
Thereby, the double container 1 shown in FIG. 1 in which the inner container 2 is detachably laminated on the inner surface of the outer container 3 can be manufactured.
In this blow molding, it is not necessary to use a stretching rod.

  In particular, since the mouth 12 and the introduction hole 15a in the first preform 3A are closed by the second preform 2A during the setting step, the blow molding can be performed while maintaining this closed state. Moreover, since the second preform 2A is pressed against the first preform 3A side by the pressure of high-pressure air or a stretching rod, the folded portion 11a is in close contact with the mouth portion 12 of the first preform 3A, and the protrusion 16 is pushed into the introduction cylinder 15. For this reason, the closed state is ensured.

Therefore, according to the manufacturing method described above, blow molding is performed with the mouth portion 12 and the introduction hole 15a in the first preform 3A being closed, so that the inner container is in the process of lowering the temperature of the double container 1 after blow molding. Even if 2 is going to contract more greatly than the outer container 3, the pressure in the portion between the inner container 2 and the outer container 3 generated by the contraction deformation is maintained at a negative pressure. Therefore, shrinkage deformation of the inner container 2 can be suppressed.
In addition, the projection part 16 and the introduction cylinder part 15 are designed (for example, friction resistance force, uneven | corrugated fitting, etc.) so that it may become a fitting force which does not detach | leave by the contraction force of the inner container 2. FIG.
Thereby, inconveniences such as peeling of the inner container 2 from the outer container 3 at the stage before use can be prevented, and the quality as the double container 1 can be improved.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above embodiment, the double container 1 is a double container in which the inner container 2 is detachably stacked on the inner surface of the outer container 3, but the present invention is not limited to this. A double container in which a gap is secured between the container 3 and the container 3 may be used.

Moreover, in the said embodiment, although the opening part 12 and the introduction hole 15a in 1st preform 3A were obstruct | occluded using 2nd preform 2A itself, it is not limited to this case, separate obstruction | occlusion means etc. May be used to close the mouth portion 12 and the introduction hole 15a from the outside of the first preform 3A.
However, as in the above-described embodiment, by using the second preform 2A, the mouth 12 and the introduction hole 15a in the first preform 3A are closed, so that efficient work can be performed from the setting process to the blowing process. It is more preferable because the double container 1 can be quickly released from the blow mold after the blow step to increase the productivity.

Further, in the setting process, as shown in FIG. 5, the plug body 20 for closing the introduction hole 15a is inserted into the introduction cylinder portion 15 of the first preform 3A, and then the first preform 3A is inserted. The second preform 2A may be housed inside. By doing so, the plug body 20 can be pressed against the inner side of the introduction cylinder portion 15 by the projection portion 16 of the second preform 2A, and the introduction hole 15a is more reliably blocked using the projection portion 16 and the plug body 20. Can be made.
However, in this case, the protrusion 16 may be omitted.

The plug body 20 may be made of the same resin material as the first preform 3A or the second preform 2A. Further, the shape may be a wedge shape as illustrated, or may be a spherical shape or an elliptical shape.
Further, the plug body 20 can be moved from the initial position arranged above the introduction cylinder part 15 to the closed position arranged below the introduction cylinder part 15 by the blowing process, and the introduction hole 15a is partially at the initial position. The introduction hole 15a may be completely closed at the closed position.
For example, in the initial position, the outer diameter of the plug body 20 is formed smaller than the inner diameter of the introduction cylinder portion 15 or a groove is formed on the outer surface of the plug body 20 or the inner surface of the introduction cylinder portion 15. Partial open state.

  When the plug 20 is used, the outer container 3 may be cut along the cutting line M located between the plug 20 and the protrusion 16 after blow molding. Further, instead of cutting, for example, an external force may be applied to the plug body 20 from the introduction hole 15a side and pushed into the inside of the introduction cylinder portion 15, and the introduction hole 15a may be opened through a gap formed thereby. Absent.

In the setting process, the introduction hole 15a may not be closed, and the introduction hole 15a may be closed from the start to the end of the blowing process.
In this case, even when the second preform 2A is smaller than the first preform 3A, the two can be closely adhered.

1 ... Double container
DESCRIPTION OF SYMBOLS 2 ... Inner container 2A ... 2nd preform 3 ... Outer container 3A ... 1st preform 15a ... Introduction hole 20 ... Plug

Claims (3)

An inner container that accommodates the contents, has a bottomed cylindrical projection protruding downward from the lower end , and is reduced in volume as the contents decrease,
The inner container is internally provided and has a cylindrical introduction tube portion projecting downward from the lower end portion, and an introduction portion in which outside air is introduced between the opening portion of the introduction tube portion and the inner container A method of manufacturing a double container comprising a hole and an outer container,
The bottomed cylindrical first preform in which the introduction cylindrical portion is formed is formed into a bottomed cylindrical shape with a material having a thermal contraction rate larger than that of the material forming the first preform, and the protrusion is A setting step of setting the formed second preform;
A heating step of heating the first and second preforms to a temperature at which they can be stretched;
A blow step of forming a double container by simultaneously blow-molding the first and second preforms in a state where the introduction hole in the first preform is closed ;
During the setting step, by inserting the projection into the introduction tube portion, the introduction hole is closed using the second preform,
A method of manufacturing a double container , wherein the protruding portion is fitted into the introducing cylinder portion by pushing the protruding portion into the introducing cylinder portion during the blowing step . In the manufacturing method of the double container of Claim 1 ,
A method for manufacturing a double container, wherein the introduction hole is closed when the first and second preforms are stretched in the axial direction by a stretching rod in the blowing step. In the manufacturing method of the double container of Claim 1 or 2 ,
Prior to the setting step, a double container manufacturing method is characterized in that a plug is placed in the introduction hole in the first preform and the closed state of the introduction hole is maintained by the plug.

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