JP7658758B2 - Synthetic resin containers and preforms - Google Patents

Description

The present invention relates to a synthetic resin container having a light-transmitting portion that allows the liquid level of the content to be visually observed, and a preform for blow molding such a synthetic resin container.

Conventionally, a synthetic resin container has been known in which a bottomed cylindrical preform is formed using a thermoplastic resin such as polyethylene terephthalate, and then this preform is molded into a bottle shape by biaxial stretch blow molding or the like.

In recent years, this type of synthetic resin container has come to be widely used for a variety of purposes, including but not limited to beverages and seasonings, and various improvements have been made to suit the purpose. For example, Patent Document 1 proposes a synthetic resin windowed container in which the container itself is made opaque with a colored resin to protect the contents from ultraviolet light, and a vertical band-shaped window made of transparent or semi-transparent resin is formed so that the state of the contents can be seen when refilling and using the container. The windowed container is produced by blow molding a preform in which a vertical band-shaped portion made of transparent or semi-transparent resin is formed at a predetermined peripheral position of a peripheral wall made of opaque resin.

In Patent Document 1, the preform is molded by co-injection, which makes it difficult to fine-tune the formation of the vertical bands in the preform, and there is also variation between shots, which limits the degree of freedom when designing the shape of the window, and can lead to an unclear boundary between the peripheral wall made of opaque resin and the window made of transparent or translucent resin.

JP 2014-108796 A

The inventors of the present invention have completed this invention as a result of extensive research into providing a synthetic resin container with a light-shielding layer that allows the liquid inside to be viewed.

The preform according to the present invention is a bottomed cylindrical preform having a mouth and a body, the body being formed with a protrusion extending in a band shape along the axial direction, and including a light-transmitting layer having one or more thick portions formed parallel to the protrusion on the radially opposite side of the position where the protrusion is formed, and a light-shielding layer laminated on the side of the light-transmitting layer where the protrusion is formed, with the portion overlapping the protrusion partially missing and covering the thick portion at the portion overlapping the thick portion.

The synthetic resin container according to the present invention has a mouth portion which serves as an inlet for pouring the liquid content, and a storage portion in which the liquid content is stored, and the storage portion is configured to include a light-transmitting layer on which a strip-like protrusion extending along the axial direction is formed, and on the radially opposite side to the position where the protrusion is formed, one or more thick portions are formed parallel to the protrusion, and a light-shielding layer which is laminated on the side of the light-transmitting layer on which the protrusion is formed, is partially missing at the portion overlapping the protrusion, and covers the thick portion at the portion overlapping the thick portion.

The present invention provides a synthetic resin container having a light-shielding layer that allows the liquid inside to be viewed, and a preform for blow molding such a container.

1 is a perspective view showing an outline of a synthetic resin container according to a first embodiment of the present invention. 1 is a front view showing an outline of a synthetic resin container according to a first embodiment of the present invention. This is a cross-sectional view taken along line AA in FIG. FIG. 2 is an explanatory view showing an example of a preform according to the first embodiment of the present invention. This is a cross-sectional view taken along line B-B of FIG. FIG. 2 is an explanatory view showing a preform intermediate in an example of the preform according to the first embodiment of the present invention. This is a cross-sectional view taken along the line CC of FIG. FIG. 4 is an explanatory view showing a modified example of the preform according to the first embodiment of the present invention. This is a cross-sectional view taken along the line D-D of FIG. 8. FIG. 2 is a cross-sectional view showing a modified example of the synthetic resin container according to the first embodiment of the present invention. FIG. 11 is an explanatory view showing another modified example of the preform according to the first embodiment of the present invention. This is a cross-sectional view taken along line E-E of FIG. FIG. 4 is a cross-sectional view showing another modified example of the synthetic resin container according to the first embodiment of the present invention. 4 is a front view showing an outline of a synthetic resin container according to a second embodiment of the present invention. FIG. This is a cross-sectional view taken along the line FF in FIG. 14. FIG. 4 is an explanatory view showing an example of a preform according to a second embodiment of the present invention. This is a cross-sectional view taken along line GG in Figure 16. FIG. 11 is an explanatory view showing another example of a synthetic resin container according to the present invention. FIG. 11 is an explanatory view showing another example of a synthetic resin container according to the present invention.

A preferred embodiment of the present invention will now be described with reference to the drawings.

[First embodiment]
First, a first embodiment of the present invention will be described.
Fig. 1 is a perspective view showing an outline of a synthetic resin container according to this embodiment, and Fig. 2 is a front view of the same. Fig. 3 is a cross-sectional view taken along line A-A in Fig. 2, but the wall thickness shown in the cross-section is exaggerated and does not reflect the actual dimensions. The same is true for the cross-section of the container 1 shown in Fig. 2, which is partially cut away.

The container 1 shown in these figures has a mouth 2 which serves as an inlet/outlet for the liquid content, and a storage section 3 in which the internal solution is stored. The storage section 3 can be molded to include a body 4 whose upper end in the height direction tapers toward the mouth 2 and connects to the lower end of the mouth 2, and a bottom 5 which closes the lower end side in the height direction of the body 4. In the example shown, the container 1 is molded to have a roughly cylindrical container shape, but the shape of the container 1 is not limited to this.

Here, the height direction refers to the direction perpendicular to the horizontal plane when the container 1 is placed upright on the horizontal plane with the mouth 2 side facing up, and the up-down, left-right and length-width directions of the container 1 are defined as shown in Figure 2 when the container is placed upright with the mouth 2 side facing up.

In the illustrated example, the circumferential surface of the cylindrical opening 2 is provided with an engagement protrusion 2a for attaching a lid (not shown) by tapping, but the means for attaching the lid is not limited to this. A screw thread may be provided instead of the engagement protrusion 2a so that the lid can be attached by screwing.
Further, an annular neck ring 2b is provided on the lower end side of the mouth portion 2 so as to protrude outward in the circumferential direction.

In this embodiment, the storage section 3 includes a light-transmitting layer 3a located on the inner layer side and a light-shielding layer 3b located on the outer layer side, and the light-transmitting layer 3a is formed with a ridge portion 6 extending in a strip shape along the axial direction. The light-shielding layer 3b is laminated on the side of the light-transmitting layer 3a where the ridge portion 6 is formed, and is partially missing at the portion overlapping the ridge portion 6, thereby reducing the light-shielding property at that portion. As a result, the liquid content can be visually confirmed through the portion with reduced light-shielding property, and for example, when refilling the liquid content into the container 1, the appropriate amount of liquid content can be refilled while visually checking the liquid level of the liquid content to prevent the liquid content from overflowing.

In order to make the contents visible in this way, it is preferable to partially remove the light-shielding layer 3b so that the light-shielding layer 3b is discontinued at the portion overlapping the protrusion 6, and the protrusion 6 is exposed flush with the light-shielding layer 3b (see Figure 3). Although not specifically shown, if the light-shielding properties can be reduced to the extent that the contents can be visible, the light-shielding layer 3b may be partially removed so that the thickness of the light-shielding layer 3b is thinner at the portion overlapping the protrusion 6.

In this embodiment, the container 1 can be molded to have a predetermined container shape, for example, by blow molding a preform 10 as shown in FIG. 4.

Figure 4 shows an example of a preform 10 for blow molding a container 1. The preform 10 is formed in a bottomed cylindrical shape with a mouth 20 formed at the upper end and a body 30 that is closed in a semi-spherical shape at the lower end.

Here, the up-down, left-right and length-width directions of the preform 10 are defined as being in the state shown in FIG. 4 with the mouth portion 20 side facing up.
5 is a cross-sectional view taken along line B--B of FIG. 4, but the wall thicknesses shown in the cross-section are exaggerated and do not reflect the actual dimensions.

The mouth 20 of the preform 10 is not stretched by blow molding, but rather maintains its appearance to become the mouth 2 of the container 1. The mouth 20 of the preform 10 is provided with an engaging protrusion 2a and a neck ring 2b, which are indicated by the same reference numerals as those given to the container 1. As described below, the preform 10 is blow molded to have a predetermined container shape by stretching the body 30 starting from below the neck ring 2b provided on the mouth 20 and molding it to become the storage section 3 of the container 1.

In the example shown in FIG. 4, the body 30 of the preform 10 is formed to include a light-transmitting layer 30a that is molded into the light-transmitting layer 3a that forms the storage section 3 of the container 1, and a light-shielding layer 30b that is molded into the light-shielding layer 3b, each of which is integrally blow molded. The light-transmitting layer 30a is formed with a protrusion 60 that extends in a strip shape along the axial direction, and this protrusion 60 is formed to become the protrusion 6 formed in the light-transmitting layer 3a. The light-shielding layer 30b is laminated on the side of the light-transmitting layer 30a on which the protrusion 60 is formed, so that the portion overlapping the protrusion 60 formed in the light-transmitting layer 30a is partially missing (see FIG. 5), and the configuration of the body 30 of the preform 10 is reflected in the configuration of the storage section 3 of the container 1 formed by blow molding the preform 10.

A resin material that forms the light-transmitting layer 30a (i.e., a resin material that forms the light-transmitting layer 3a) can be a light-transmitting resin. For example, a thermoplastic polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, amorphous polyarylate, polylactic acid, polyethylene furanoate, or a copolymer thereof can be used, and in particular, an ethylene terephthalate-based thermoplastic polyester such as polyethylene terephthalate can be preferably used.

In addition, as the resin material forming the light-shielding layer 30b (i.e., the resin material forming the light-shielding layer 3b), for example, a colored resin prepared to a desired hue by blending a coloring agent such as a pigment with the above-mentioned resin, or a foamable resin containing a predetermined amount of foaming agent in the resin by dissolving an inert gas such as carbon dioxide gas or nitrogen gas as a physical foaming agent, or a pyrolyzable compound such as a carbonate that generates carbon dioxide gas by thermal decomposition or an azo compound that generates nitrogen gas by thermal decomposition as a chemical foaming agent in the molten resin when the above-mentioned resin is melted and kneaded, can be used. Considering the recyclability of the container 1, it is preferable to make the light-shielding property manifest by a foam structure formed by foaming the foamable resin as described below.

Such a preform 10 can be molded by an injection molding method known as two-color molding or double molding, for example, as follows.

First, a core mold 200 for molding the inner peripheral surface of the preform 10 and the upper end surface of the mouth portion 20, a mouth mold 201 for molding the peripheral surface side of the mouth portion 20 including the upper surface and peripheral end surface of the neck ring 2b, and a primary body mold 202a for molding the peripheral surface side of the light-transmitting layer 30a including the lower surface of the neck ring 2b and the protrusion portion 60 are clamped together, and a resin material for forming the light-transmitting layer 30a is injected into the cavity (primary injection process). As a result, a preform intermediate 10a shown in FIG. 6 in which the mouth portion 20 and the light-transmitting layer 30a are integrally molded is injection molded.
7 is a cross-sectional view taken along line CC of FIG. 6, but the wall thicknesses shown in the cross-section are exaggerated and do not reflect the actual dimensions.

Next, instead of the primary body mold 202a, a secondary body mold 202b is used, which is configured to form a gap between the molded preform intermediate body 10a and the secondary body mold 202b to form the light-shielding layer 30b, and the mold is then clamped again, and the resin material that forms the light-shielding layer 30b is injected (secondary injection process). As a result, as shown in FIG. 5, the light-shielding layer 30b is injection molded on the peripheral surface of the light-transmitting layer 30a except for the area where the protrusion 60 is formed. However, when a foamable resin is used as the resin material that forms the light-shielding layer 30b, it is preferable from the standpoint of light-shielding properties and appearance to maintain high pressure inside the cavity and inject the resin while maintaining pressure so that the foamable resin can be prevented from breaking during its flow and from foaming after filling.

By going through such a primary injection process and a secondary injection process, a preform 10 can be molded that has a body 30 including a light-transmitting layer 30a on which a ridge 60 extending in a band shape along the axial direction is formed, and a light-shielding layer 30b that is laminated on the side of the light-transmitting layer 30a on which the ridge 60 is formed and has a portion that overlaps the ridge 60 partially missing.

Here, if the light-transmitting layer 30a has a single protrusion 60, the resin pressure when the resin material is injected into the cavity in the primary injection process does not act evenly in the circumferential direction on the core mold 200, and the core mold 200 is pushed from the side where the protrusion 60, which has a relatively large amount of resin, is formed, causing it to tilt, which may result in uneven thickness in the molded preform intermediate 10a.

In this embodiment, in order to effectively avoid such a problem, it is preferable to form multiple protrusions 60 (two in the illustrated example) on the light-transmitting layer 30a and arrange them symmetrically about the central axis. This cancels out the resin pressure acting on the core mold 200 from the side where one protrusion 60 is formed and the resin pressure acting on the core mold 200 from the side where the other protrusion 60 is formed, preventing the core mold 200 from tilting.

If the inclination of the core mold 200 can be effectively prevented against the resin pressure acting on the core mold 200 from the side where the protrusions 60 are formed, one or more thick portions 60a may be formed parallel to the protrusions 60 on the radially opposite side to the position where the protrusions 60 are formed, as in the modified examples shown in Figures 8 and 9, or other modified examples shown in Figures 11 and 12. Such thick portions 60a can be appropriately designed according to the resin pressure acting on the core mold 200 from the side where the protrusions 60 are formed, in other words, the amount of resin forming the protrusions 60.
9 is a cross-sectional view taken along the line D-D of FIG 8, but the thicknesses shown in the cross-section are exaggerated and do not reflect the actual dimensions. The same is true for the cross-sectional view taken along the line E-E of FIG 11 shown in FIG 12.

The preform 10 is softened by heating to a state where it can be blow molded, and then set in a blow mold (not shown). If necessary, it is stretched in the axial direction (vertical direction) by a stretching rod, and is stretched in the axial and circumferential directions (horizontal direction) by blown air blown into the preform 10. At this time, the body 30 is stretched starting from below the neck ring 2b provided at the mouth 20, and the cavity shape of the blow mold is transferred, so that the stretched body 30 is molded to become the storage section 3 of the container 1.

The preform 10 can be heated, for example, by an infrared heater. In this case, the mouth portion 20 is covered with a shielding body so that the body portion 30 is selectively heated. When a foamable resin is used as the resin material for forming the light-shielding layer 30b, the preform 10 as a precursor in which the light-shielding layer 30b is formed of a non-foamed foamable resin is subjected to such a heat treatment to foam the foamable resin, thereby changing the internal structure of the light-shielding layer 30b so that it has a foamed structure containing a large number of bubbles. As a result, the light-shielding layer 3b formed by the light-shielding layer 30b has a foamed structure containing a large number of bubbles, and the light-shielding properties can be expressed by such a foamed structure.

By blow molding the preform 10 in this manner, a container 1 as described above can be molded, in which the liquid content is visible. However, when a preform 10 is used in which multiple protrusions 60 are formed in the light-transmitting layer 30a so that they are arranged symmetrically about the central axis, multiple protrusions 6 are formed symmetrically about the central axis in the light-transmitting layer 3a of the molded container 1 (see Figure 3).

Furthermore, when a preform 10 is used in which one or more thick portions 60a are formed parallel to the protrusion portion 60 on the radially opposite side of the position where the protrusion portion 60 is formed, as in the modified example shown in Figures 8 and 9, or other modified example shown in Figures 11 and 12, one or more thick portions 6a are formed parallel to the protrusion portion 6 on the radially opposite side of the position where the protrusion portion 6 is formed in the light-transmitting layer 3a of the molded container 1 (see Figures 10 and 13).
Note that Figure 10 shows a cross-section (a cross-section corresponding to the A-A cross-section in Figure 2) of the storage section 3 of the container 1 molded using the preform 10 shown in Figures 8 and 9, and Figure 13 shows a cross-section (same as above) of the storage section 3 of the container 1 molded using the preform 10 shown in Figures 11 and 12, but the wall thicknesses appearing in these cross-sections are exaggerated and do not reflect the actual dimensions.

In addition, in order to improve the visibility of the liquid level of the content liquid when refilling the container 1 with the content liquid, it is preferable that the mouth portion 2 is translucent so that the liquid level of the content liquid can be seen even through the mouth portion 2. According to this embodiment, in the primary injection process in which the preform 10 is injection molded as described above, the mouth portion 20 and the translucent layer 30a are molded integrally using a resin material that forms the translucent layer 30a, thereby molding a preform 10 in which the mouth portion 20 has translucency. Therefore, in the container 1 formed by blow molding the preform 10, the mouth portion 2 can be molded to have translucency.

[Second embodiment]
Next, a second embodiment of the present invention will be described.
Fig. 11 is a front view showing an outline of a synthetic resin container according to this embodiment. Fig. 12 is a cross-sectional view taken along the line E-E of Fig. 11, but the wall thickness shown in the cross-section is exaggerated and does not reflect the actual dimensions. The same is true for the cross-section of the container 1 shown in Fig. 11, which is partially cut away.

In the first embodiment described above, the storage section 3 of the container 1 is configured so that the light-transmitting layer 3a on which the ridges 6 extending in a band shape along the axial direction are formed is located on the inner layer side, and the light-shielding layer 3b, which is laminated on the side of the light-transmitting layer 3a on which the ridges 6 are formed and is partially missing where it overlaps with the ridges 6, is located on the outer layer side. In contrast, the container 1 in this embodiment has the same appearance as the first embodiment, but differs from the first embodiment in that the storage section 3 is configured so that the light-transmitting layer 3a is located on the outer layer side and the light-shielding layer 3b is located on the inner layer side. This embodiment will be described below, focusing on the differences from the first embodiment.

FIG. 13 shows an example of a preform 10 for blow molding the container 1 in this embodiment. The preform 10 is configured such that the light-shielding layer 30b is partially missing at a portion overlapping with the protrusion 60 formed in the light-transmitting layer 30a located on the outer layer side, and is molded integrally with the mouth portion 20, and the protrusion 60 formed in the light-transmitting layer 30a is embedded in the missing portion of the light-shielding layer 30b located on the inner layer side (see FIG. 14).
It should be noted that Fig. 14 is a cross-sectional view taken along the line F-F of Fig. 13, but the wall thickness shown in the cross-section is exaggerated and does not reflect the actual dimensions. The same is true for the cross-section of the preform 10 shown in Fig. 13, which is partially cut away.

Such a preform 10 can be molded in the same manner as described in the first embodiment, but in the primary injection process in which the preform intermediate 10a is injection molded, the mouth portion 20 and the light-shielding layer 30b are molded integrally with the resin material that forms the light-shielding layer 30b. Then, in the secondary injection process, the light-transmitting layer 30a is injection molded.

The preform 10 thus molded can be molded into a container 1 by being set in a blow mold after heat treatment and blow molding in the same manner as in the first embodiment, but in this embodiment, the mouth 20 of the preform 10 is molded integrally with the light-shielding layer 30b. Therefore, when a foamable resin is used as the resin material for forming the light-shielding layer 30b, the mouth 20 is also formed of the foamable resin. Even in this case, when the preform 10 is heated prior to blow molding, the mouth 20 is covered with a shield so that the body 30 is selectively heated, so that the foamable resin forming the mouth 20 is prevented from foaming, while the foamable resin forming the light-shielding layer 30b is foamed, and the internal structure of the light-shielding layer 30b can be changed to have a foamed structure containing a large number of bubbles formed thereby. Furthermore, by making the mouth 20 of the preform 10 non-foamed, the mouth 2 of the container 1 produced by blow molding the preform 10 can be molded to have translucency, as in the first embodiment, and this also makes it possible to improve the visibility of the liquid level of the contents.

As described above, this embodiment differs from the first embodiment in the above respects, but other configurations are common to the first embodiment, so redundant explanations of the configurations common to the first embodiment will be omitted.

The present invention has been described above with reference to preferred embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention.

According to the present invention, the container 1 having the light-shielding layer 3b through which the liquid content can be seen can be designed with a high degree of freedom so as to improve the design and functionality. For example, as shown in Fig. 15, the protrusions 6 formed on the light-transmitting layer 3a may be formed separately on the upper and lower sides of the storage section 3. By adopting such an embodiment, it is possible to reduce the range in which the light-shielding properties of the light-shielding layer 3b are reduced, and to better suppress the deterioration of the liquid content due to light, while at the time of refilling the liquid content, it is possible to make the liquid level of the liquid content visible on the upper side of the storage section 3 and the remaining amount of the liquid content visible on the lower side of the storage section 3. Furthermore, as shown in Fig. 16, the light-shielding layer 3b can be formed in the range excluding the upper side of the storage section 3 so that the liquid level of the liquid content can be better seen on the upper side of the storage section 3.
In both Figs. 15 and 16, the wall thicknesses shown in the cross sections of partially cut away container 1 are exaggerated and do not reflect the actual dimensions.

1 Container 2 Mouth 3 Storage part 3a Transparent layer 3b Light shielding layer 6 Projection 6a Thick part 10 Preform 20 Mouth 30 Body 30a Transparent layer 30b Light shielding layer 60 Projection 60a Thick part

Claims (2)

A bottomed cylindrical preform having a mouth and a body, the body being formed with a protrusion extending in a band shape along the axial direction, and a light-transmitting layer having one or more thick portions formed parallel to the protrusion on the radially opposite side of the position where the protrusion is formed, and a light-shielding layer laminated on the side of the light-transmitting layer where the protrusion is formed, with the portion overlapping the protrusion partially missing and covering the thick portion at the portion overlapping the thick portion. The container has an opening for injecting the liquid content and a storage section for storing the liquid content.
a light-transmitting layer on the radially opposite side of the protrusion, the light-shielding layer being partially missing at a portion overlapping the protrusion and covering the thick-walled portion at a portion overlapping the thick-walled portion.

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