JP2021181314A - Double container, manufacturing method of double container, and double preform - Google Patents

Abstract

To provide a double container in which functionality for maintaining the quality of a content has been further improved, a manufacturing method of a double container, and a double preform.SOLUTION: In a double container 1, an inner container 20 which stores a content and which is shrinkable, and an outer container 10 which includes the inner container 20 are peelable. It includes a function film 30 which is arranged between the inner container 20 and the outer container 10, and which has a function layer 31 in which a functional material for maintaining the quality of a content is formed into a film-like shape. The function film 30 has an adhesive property to the inner container 20 so as to follow the shrinkage of the inner container 20.SELECTED DRAWING: Figure 1

Description

The present invention relates to a double container in which an outer container and an inner container are detachably configured, a method for manufacturing a double container, and a double preform.

In recent years, as a container for polyethylene terephthalate (PET resin) that contains contents such as beverages, liquid seasonings or liquid cosmetics and maintains its freshness, a double container configured so that the outer container and the inner container can be peeled off. Is known (for example, Patent Document 1).

Further, in order to maintain the quality of the contents, it is known that in the double container formed of PET resin, the inner container for accommodating the contents contains a blended resin material having a gas barrier property (for example). Patent Document 2).

Here, it is known that the gas barrier property is roughly classified into an active barrier property that absorbs oxygen such as an oxygen absorber and a passive barrier property that prevents the invasion of oxygen.

Japanese Unexamined Patent Publication No. 2017-186059 Japanese Unexamined Patent Publication No. 2017-13833

However, even if a blended resin material containing an oxygen absorber having an active barrier property is used for the inner container, the oxygen absorber absorbs oxygen over time after long-term storage, and the oxygen barrier due to the oxygen absorber. Sex is deactivated.

Further, even if a blended resin material containing a barrier agent having a passive barrier property is used for the inner container, the blended resin containing the PET resin and the barrier agent looks like a sea island on a microscopic scale, for example, an island. Although the in-like barrier agent prevents the invasion of oxygen, the sea-like PET resin allows air to pass through. Furthermore, from the viewpoint of recycling, the proportion of the content of the barrier agent contained in the PET resin is limited.

In particular, in a double container in which the outer container and the inner container can be separated from each other, when the inner container contracts due to the discharge of the contents, air flows between the outer container and the inner container. It has been desired to further improve the functionality for maintaining the quality of the contents.

The present invention has been made in view of the above circumstances, and by providing a double container, a method for manufacturing a double container, and a double preform having further improved functionality for maintaining the quality of the contents. be.

The double container according to the present invention is a double container in which an inner container that can accommodate and shrink the contents and an outer container that contains the inner container are detachably configured, and the inner container and the outer container are detachable. A functional film having a functional layer formed between a container and a functional material that maintains the quality of the contents in the form of a film is provided, and the functional film has the contents so as to follow the shrinkage of the inner container. It is characterized by having adhesiveness to the container.

The method for manufacturing a double container according to the present invention is a method for manufacturing a double container in which an inner container that can accommodate and shrink the contents and an outer container that contains the inner container can be peeled off. A functional film having a functional layer formed of a functional material for maintaining the quality of the contents into a film is sandwiched between the inner preform in which the inner container is molded and the outer preform in which the outer container is molded. In the stacking process of preparing the double preform, the double preform is heated and blown from the inside of the double preform to integrate the inner preform, the outer preform, and the functional film. The functional film is fused to the inner container by the heat and pressure of the blow in the stretching blow step so as to follow the shrinkage of the inner container. It is characterized by that.

The double preform according to the present invention is a double preform formed into a double container in which an inner container that can accommodate and shrink the contents and an outer container that contains the inner container can be peeled off. A functional layer is formed between the inner preform in which the inner container is molded and the outer preform in which the outer container is molded, and the functional material that maintains the quality of the contents is formed into a film. The functional film is characterized by having adhesiveness to the inner container so as to follow the shrinkage of the inner container.

According to the present invention, it is possible to provide a double container, a method for manufacturing a double container, and a double preform with further improved functionality for maintaining the quality of the contents.

It is a figure which shows the vertical cross section of a double container schematically. It is a figure which shows the vertical cross section of a functional film schematically. It is a figure which shows the vertical cross section of a double preform schematically. It is a figure which shows the manufacturing process of a double container. It is a table which shows the evaluation result of a double container.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the present embodiment, the direction along the central axis Z of the double container 1 having a bottle shape is also referred to as "axial direction", and the direction of orbiting around the central axis Z of the double container 1 as the rotation axis is also referred to as "circumferential direction". The direction orthogonal to the central axis Z of the double container 1 is also referred to as "diametrical direction". Further, the axial direction from the mouth 3 to the bottom 6 of the double container 1 is also referred to as "downward", and the axial direction from the bottom 6 to the mouth 3 of the double container 1 is also referred to as "upward". Further, a cross section obtained by cutting the double container 1 on a plane along the central axis Z of the double container 1 is also referred to as a "vertical cross section", and the double container 1 is cut on a plane orthogonal to the central axis Z of the double container 1. The cross section is also referred to as a "cross section".

[Structure of double container 1]
FIG. 1 is a diagram schematically showing a vertical cross section of the double container 1 according to the present embodiment.

As shown in FIG. 1, the double container 1 is a container made of synthetic resin having a bottle shape, and has a mouth portion 3 which is one end of the double container 1 and has a spout 21 for contents, and a double container. A bottom portion 6 which is the other end of 1 and has a ground contact surface, a shoulder portion 4 which extends outward from the mouth portion 3 in the radial direction and extends downward from the mouth portion 3, and a body portion 5 which extends downward from the shoulder portion 4 and is connected to the bottom portion 6. To prepare for. Examples of the contents of the double container 1 include beverages such as tea and coffee, liquid seasonings such as soy sauce, and liquid cosmetics such as shampoo.

Further, the double container 1 has a bottle-shaped outer container 10 that constitutes the outer shell of the double container 1 and contains the inner container 20, and a content that contains the contents and has a shape along the inner surface of the outer container 10. A vessel 20 and a functional film 30 fused to the outer surface of the inner container 20 are provided. In the double container 1, a gap A is formed between the outer container 10 and the inner container 20 to which the functional film 30 is fused, and the outer container 10 and the inner container 20 are configured to be detachable. ..

The outer container 10 and the inner container 20 are a polyolefin resin, an ethylene-vinyl copolymer, a styrene resin, a vinyl resin, a polyamide resin, a polyester resin, a polycarbonate resin, a polyphenylene oxide resin, or a raw material. It is molded using a degradable resin. Preferably, the outer container 10 and the inner container 20 are molded using a polyolefin-based resin or a polyester-based resin. More preferably, the outer container 10 and the inner container 20 are molded using a polyester resin. Examples of the polyester-based resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and resins such as copolymerized polyesters thereof. Particularly preferably, the outer container 10 and the inner container 20 are molded using a polyethylene terephthalate resin (hereinafter referred to as “PET resin”).

In the present embodiment, the thickness of the outer container 10 is formed to be about 400 μm, and the thickness of the inner container 20 is formed to be about 100 μm. The thickness of the outer container 10 and the inner container 20 can be freely changed in design.

The functional film 30 is a non-stretched film that functions to maintain the quality of the contents, and is fused to the inner container 20 by the heat and pressure of the blow in the stretch blow molding when the outer container 10 and the inner container 20 are manufactured. Will be done.

[Structure of functional film 30]
FIG. 2 is a diagram schematically showing a vertical cross section of the functional film 30 according to the present embodiment. Further, FIG. 2A is an example of a vertical cross section of the functional film 30 according to the present embodiment, and FIG. 2B is an example of a vertical cross section of the functional film 30 according to a modified example of the present embodiment. ..

As shown in FIG. 2A, the functional film 30 faces the inner container 20 and is laminated on the functional layer 31 and the functional layer 31 in which the functional material that maintains the quality of the contents is formed in the form of a film. It has a three-layer structure having a back surface layer 32 facing the outer container 10 and a surface layer 33 laminated on the functional layer 31.

In the present embodiment, the film thickness of the functional film 30 is such that the film thickness of the functional layer 31 is about 5 to 10 μm, the film thickness of the back surface layer 32 is about 2 to 4 μm, and the film thickness of the front surface layer 33 is about 3 to 5 μm. It is formed from the film thickness, and is formed so that the film thickness of the functional layer 31 is the thickest. The film thicknesses of the functional layer 31, the back surface layer 32, and the front surface layer 33 of the functional film 30 can be freely changed in design.

The functional layer 31 is formed by using a gas barrier material having a gas barrier property as the functional material. It is desirable to mold using MXD6, polyethylene naphthalate (PEN), and polyethylene furanoate (PEF), and particularly preferably, it is desirable to mold the functional layer 31 using MXD6.

The back surface layer 32 and the front surface layer 33 are molded using a polyester resin. It is desirable that the inner container 20 is molded using the same resin as the inner container 20, and it is particularly preferable that the inner container 20, the back surface layer 32 and the front surface layer 33 are molded using the polyethylene terephthalate resin. ..

In particular, since the inner container 20 and the back surface layer 32 are molded using the same resin polyethylene terephthalate resin, they are easily fused to the inner container 20 by the heat and pressure of the blow in the stretch blow molding, and the inner container 20 is easily fused. When the inner container 20 shrinks, the adhesiveness can be imparted so as to follow the shrinkage of the inner container 20.

Further, as shown in FIG. 2B, the inner container 20 and the back surface layer 32 do not have to be molded using the same resin polyethylene terephthalate resin, and the inner container 20 is made of polyethylene terephthalate and a functional material. It may be molded using a blended resin material that has been blended. As described above, by molding the inner container 20 using the blended resin material, it is possible to further enhance the functionality of maintaining the quality of the contents of the functional material.

Further, although not shown in FIG. 2, fusion prevention prevents fusion between the outer container 10 and the functional film 30 on the inner surface side of the surface layer 33 of the functional film 30 or the outer container 10. Layers are formed. The fusion prevention layer will be described in detail later with reference to FIG.

In the present embodiment, the functional layer 31 is molded by using a gas barrier material having a gas barrier property as the functional material, but the functional layer 31 may be molded by using a material having a light-shielding property and a heat retaining property.

Further, the functional film 30 may be composed of three or more layers instead of the three-layer structure having the functional layer 31, the back surface layer 32, and the front surface layer 33. Further, the functional film 30 may have a two-layer structure including the functional layer 31 and the back surface layer 32. As described above, even if the functional film 30 has a two-layer structure of the functional layer 31 and the back surface layer 32, the quality of the contents made of the functional material can be improved while imparting adhesiveness so as to follow the shrinkage of the inner container 20. The functionality to be retained can also be imparted.

[Structure of double preform 500]
FIG. 3 is a diagram schematically showing a vertical cross section of the double preform 500 according to the present embodiment. Further, FIG. 3A is a diagram schematically showing a step of preparing the double preform 500, and FIG. 3A is a diagram schematically showing the double preform 500.

As shown in FIG. 3B, in the double preform 500, the tubular outer preform 100 in which the outer container 10 is molded, the base film 300 in which the functional film 30 is molded, and the inner container 20 are molded. It is provided with a tubular inner preform 200. By stretching blow molding the double preform 500, the double container 1 is molded. Therefore, the double preform 500 and the double container 1, the outer container 10 and the outer preform 100, the inner container 20 and the inner preform 200, and the functional film 30 and the base film 300 are functionally homogeneous.

The double preform 500 corresponds to a non-stretched portion M which corresponds to a mouth portion 3 and is not stretched by stretch blow molding, and corresponds to a shoulder portion 4, a body portion 5 and a bottom portion 6 and is stretched by stretch blow molding. It is composed of a stretched portion N which is a portion.

In the present embodiment, since the tubular outer preform 100 formed in the outer container 10 and the tubular inner preform 200 formed in the inner container 20 are before stretch blow molding, the outer container 10 and the contents thereof. It is thicker than the thickness of the vessel 20, the thickness of the outer container 10 is formed to be about 3000 μm, and the thickness of the inner container 20 is formed to be about 1500 μm. The thicknesses of the outer preform 100 and the inner preform 200 can be freely changed in design.

As shown in FIG. 2, the structure of the base film 300 formed on the functional film 30 is a three-layer structure including a functional layer 31, a back surface layer 32, and a front surface layer 33. Further, in the present embodiment, the film thickness of the base film 300 is thicker than that of the functional film 30 because it is before stretch blow molding, the film thickness of the functional layer 31 is about 50 to 100 μm, and the film thickness of the back surface layer 32 is The film thickness is about 20 to 40 μm, and the film thickness of the surface layer 33 is about 30 to 50 μm. The film thicknesses of the functional layer 31, the back surface layer 32, and the front surface layer 33 of the base film 300 can be freely changed in design.

The process of preparing the double preform 500 will be described below.

As shown in FIG. 3A, the base film 300 is formed in a cylindrical shape so that the resin layer to be the surface layer 33 of the base film 300 (functional film 30) faces the outer preform 100, and the outer film 300 is formed. Insert into reform 100. Here, when the base film 300 is formed into a cylindrical shape, an overlapping portion is formed to some extent as shown in FIG. 3 (b).

Further, when the base film 300 is inserted into the outer preform 100, the outer preform 100 (outer container 10) and the base film 300 (functional film 30) are placed on the outer surface side of the base film 300 or the inner surface side of the outer preform 100. ) To form a fusion prevention layer that prevents fusion.
Here, in the present embodiment, the lubricating oil 400 such as paraffin oil is applied as an example of the method for forming the fusion prevention layer.

Then, the inner preform 200 is placed in the cylindrically formed base film 300 so that the base film 300 is sandwiched and fixed between the outer preform 100 and the inner preform 200 at the mouth of the non-stretched portion M. insert.

As a result, as shown in FIG. 3B, the base film 300 has a functional layer in which a functional material that maintains the quality of the contents is formed in a film shape between the outer preform 100 and the inner preform 200. The double preform 500 that sandwiches the above can be prepared.

In the present embodiment, in preparing the double preform 500, after the base film 300 is formed into a cylindrical shape and inserted into the outer preform 100, the inner preform 200 is combined with the outer preform 100 and the cylindrical base. It was configured to be inserted into the film 300, but after the base film 300 was formed into a cylindrical shape and wound around the inner preform 200, the base film 300 and the inner preform 200 were configured to be inserted into the outer preform 100. You may.

Further, the base film 300 is not fixed (adhered) to the outer preform 100 or the inner preform 200 at the stretched portion N of the double preform 500, and is released at the bottom of the double preform 500. It is in a state.

[Manufacturing process of double container 1]
FIG. 4 is a diagram showing a manufacturing process of the double container 1.

As shown in FIG. 4, first, a stacking step (S10) for preparing a double preform is performed.

In the stacking step (S10), as shown in FIG. 3, a base film 300 coated with a lubricating oil 400 as a fusion prevention layer is sandwiched between the outer preform 100 and the inner preform 200. Prepare the heavy preform 500.

After the stacking step (S10) is performed, a stretching blow step (S20) for stretching blow molding the double preform 500 is performed.

In the stretching blow step (S20), first, the PET resin forming the double preform 500 is heated to a temperature equal to or higher than the glass transition temperature (Tg) and lower than the melting point (about 100 to 120 ° C.). Next, a stretch rod is inserted into the double preform 500 and stretched in the axial direction, and at the same time, a blow fluid (for example, air) is blown to expand and stretch the double preform 500 in the circumferential direction.

At this time, the inner preform 200 and the base film 300 heated to the glass transition temperature of the PET resin or higher are fused by the blow pressure, but the lubricating oil 400 exists between the outer preform 100 and the base film 300. Therefore, it is not fused and is easily peeled off.
As a result, after the double container 1 is manufactured, the functional film 30 has adhesiveness to the inner container 20 so as to follow the shrinkage of the inner container 20.

Further, since the lubricating oil 400 plays a role of reducing the frictional force between the base film 300 and the outer preform 100, the base film 300 is used in stretch blow molding even if the base film 300 is not completely fixed to the double preform 500. It is possible to prevent the (functional film 30) from being wrinkled.

In the stretching blow step (S20) of the present embodiment, the preform of the outer container 10 and the preform of the inner container 20 are used as the double preform 500 and stretch blow molded at the same time, but the outer container 10 is used. After the preform of the above is stretch blow molded, the preform of the inner container 20 may be stretch blow molded inside the outer container 10.

[Evaluation result of double container]
FIG. 5 is a table showing the evaluation results of the double container.

FIG. 5A is a table for evaluating the oxygen permeability of the double container 1, and the vertical axis represents the oxygen concentration (%) and the horizontal axis represents the elapsed time (week). Further, the dotted line indicates the double container 1 having the functional film 30 in the present embodiment, and the solid line indicates the conventional double container having no functional film 30.

Here, FIG. 5A shows the following measurement conditions.
Sealing method: Evaporated PET seal Storage conditions: Temperature 37 ° C, humidity 30% RH
Measurement method: OXY4trace (high sensitivity sensor)

As shown in FIG. 5A, it can be seen that the double container 1 having the functional film 30 in the present embodiment has about twice the gas barrier property as that of the conventional double container.

FIG. 5B is a table for evaluating the adhesiveness of the functional film 30 to the inner container 20 in the double container. Further, the inner container 20 of the double container 1 in FIG. 5B is molded of PET resin.

The "innermost layer PET" shown in FIG. 5B has a three-layer structure in which the functional film 30 has a functional layer 31, a back surface layer 32, and a front surface layer 33, and is an adhesive layer facing the inner container 20 in the functional film 30. (Back surface layer 32) is molded from the same PET resin as the inner container 20. In this "innermost layer PET", the adhesiveness between the back surface layer 32 and the inner container 20 of the PET resins is evaluated.

Further, the "innermost layer MXD6" shown in FIG. 5B has a two-layer structure in which the functional film 30 has a functional layer 31 and a surface layer 33, and the adhesive layer facing the inner container 20 in the functional film 30 is MXD6. It is the functional layer 31 formed by. In this "innermost layer MXD6", the adhesiveness between the functional layer 31 molded by MXD6 and the inner container 20 molded by PET resin is evaluated.

Here, in FIG. 5B, the inner container 20 is shrunk after manufacturing five double containers 1 each using the functional films 30 of the “innermost layer PET” and the “innermost layer MXD6”. It was restored and visually confirmed whether or not the functional film 30 was peeled off from the inner container 20.

As shown in FIG. 5B, by molding the adhesive layer of the functional film 30 facing the inner container 20 with the same PET resin as the inner container 20, the adhesiveness between the functional film 30 and the inner container 20 is improved. I can understand that.

As described above, the double container 1 according to the present embodiment is provided with the functional film 30 having the functional layer 31 formed of the functional material in the form of a film, thereby providing a quality maintaining function for maintaining the quality of the contents. It can be improved further.

Further, in the double container 1 according to the present embodiment, since the functional film 30 has adhesiveness to the inner container 20 so as to follow the shrinkage of the inner container 20, after the inner container 20 shrinks, the outer container 20 is removed. Even if the air between the container 10 and the inner container 20 flows in and the void A becomes large, the quality of the contents can be maintained for a longer period of time as compared with the conventional case. In particular, the functional film 30 has a three-layer structure, and the back surface layer 32 facing the inner container 20 is molded with the same PET resin as the inner container 20 to improve the adhesiveness between the functional film 30 and the inner container 20. Can be done.

Further, in the double container 1 according to the present embodiment, since the lubricating oil 400 is applied between the base film 300 and the outer preform 100, the outer preform 100 (outer container 10) and the base film 300 (outer container 10) are applied. It is possible to prevent the functional film 30) from being fused with the functional film 30), and it is also possible to prevent the functional film 30 from being wrinkled.

Further, in the double container 1 according to the present embodiment, when recycling as the PET resin double container 1, after crushing in the recycling step, after recycling by excluding the functional film 30 by wind force sorting or floating / sinking sorting. The quality of the can be improved.

In the above-described embodiment, each other's technique can be applied to each other including the modification. The above-described embodiment does not limit the content of the present invention, and changes can be made to the extent that the claims do not deviate from the scope of the claims.

The terms used in the above embodiments and claims should be construed as non-limiting terms. For example, the term "contains" should be construed as "not limited to what is described as including." The term "prepared" should be construed as "not limited to what is described as prepared." The term "have" should be construed as "not limited to what is described as having."

1 Double container 3 Mouth 4 Shoulder 5 Body 6 Bottom 10 Outer container 20 Inner container 30 Functional film 31 Functional layer 32 Back layer 33 Surface layer 100 Outer preform (outer container)
200 inner preform (inner container)
300 base film (functional film)
A Void M Non-stretched part N Stretched part Z Central axis

Claims (13)

A double container in which the inner container that accommodates the contents and can be shrunk and the outer container that contains the inner container can be peeled off.
A functional film having a functional layer, which is arranged between the inner container and the outer container and has a functional material formed into a film to maintain the quality of the contents, is provided.
The functional film is a double container characterized in that it has adhesiveness to the inner container so as to follow the shrinkage of the inner container. The functional film is
With the functional layer
It faces the inner container and has a back surface layer laminated on the functional layer.
The double container according to claim 1, wherein the back surface layer is fused to the inner container by heat. The functional film faces the outer container and has a surface layer laminated on the functional layer.
The double container according to claim 2, wherein a fusion prevention layer for preventing the outer container and the functional film from being fused is formed inside the surface layer or the outer container. .. The double container according to claim 2 or 3, wherein the inner container and the back surface layer are molded using a polyester resin. The functional film is
When stretch blow molding is performed in which blow is performed from the inside of the inner preform in which the inner container is molded to expand and stretch in the circumferential direction, the inner container is fused to the inner container by the heat and pressure of the blow in the stretch blow molding. The double container according to any one of claims 2 to 4, wherein the double container is made. A double container with a mouth, body and bottom,
The functional film is
At the mouth, both the inner container and the outer container are fitted and fixed.
The double container according to any one of claims 2 to 5, wherein at least a part of the bottom portion is not fused to the inner container. The double container according to any one of claims 1 to 6, wherein the functional material is a gas barrier material having a gas barrier property. A method for manufacturing a double container in which an inner container that can accommodate and shrink the contents and an outer container that contains the inner container can be peeled off.
A functional film having a functional layer formed of a functional material for maintaining the quality of the contents into a film is sandwiched between the inner preform in which the inner container is molded and the outer preform in which the outer container is molded. The stacking process to prepare the double preform,
A stretching blow step in which the double preform is heated and blown from the inside of the double preform, and the inner preform, the outer preform, and the functional film are integrally expanded and stretched in the circumferential direction. Equipped with
A method for producing a double container, wherein the functional film is fused to the inner container by the heat and pressure of the blow in the stretching blow step so as to follow the shrinkage of the inner container. The functional film faces the outer preform and has a surface layer laminated on the functional layer.
The double according to claim 8, wherein a fusion prevention layer for preventing fusion between the outer container and the functional film is formed inside the surface layer or the outer preform. How to make a container. The stacking process is
At the mouth of the double preform, the functional film is fitted and fixed together with the inner preform and the outer preform.
The method for manufacturing a double container according to claim 8 or 9, wherein the double container is manufactured. A double preform formed into a double container in which an inner container that can accommodate and shrink the contents and an outer container that contains the inner container can be peeled off.
A functional film having a functional layer formed in a film shape of a functional material that is arranged between an inner preform in which the inner container is molded and an outer preform in which the outer container is molded and maintains the quality of the contents. Equipped with
The functional film is a double preform characterized by having adhesiveness to the inner container so as to follow the shrinkage of the inner container. The functional film is
With the functional layer
It has a back surface layer that faces the inner preform and is laminated on the functional layer.
The double preform according to claim 11, wherein the back surface layer is fused to the inner container by heat. The functional film faces the outer preform and has a surface layer laminated on the functional layer.
12. The double according to claim 12, wherein a fusion prevention layer for preventing fusion between the outer container and the functional film is formed inside the surface layer or the outer preform. preform.

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