Synthetic resin containers and preforms

Abstract

To provide a synthetic resin container having a light-shielding layer that allows visual confirmation of a content liquid.SOLUTION: A container 1 comprises a mouth part 2 serving as an injection outlet for a content liquid and a storage part 3 for storing the content liquid. The storage part 3 includes: a light-transmitting layer 3a having at least one projection strip part 6 formed extending in a strip shape in an axial direction; and a light shielding layer 3b that is laminated on a side of the light-transmitting layer 3a on which the projection strip part 6 is formed, and is partially removed at a part overlapping the projection strip part 6.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a synthetic resin container having a light-transmitting portion through which the liquid level of the contained liquid can be visually observed, and a preform for blow molding such a synthetic resin container. [Background technology]

[0002] 2. Description of the Related Art Conventionally, synthetic resin containers have been known which are produced by forming a bottomed cylindrical preform using a thermoplastic resin such as polyethylene terephthalate, and then molding this preform into a bottle shape by biaxial stretch blow molding or the like.

[0003] In recent years, this type of synthetic resin container has come to be widely used for various purposes, not limited to beverages, seasonings, etc., and various improvements have been made according to 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 semitransparent resin is formed so that the filled state can be seen when refilling the contents for use, and the windowed container is produced by blow molding a preform in which a vertical band-shaped portion made of transparent or semitransparent resin is formed at a predetermined peripheral position of a peripheral wall made of opaque resin.

[0004] In Patent Document 1, the preform is molded by co-injection, which makes it difficult to fine-tune the formation of the vertical band-shaped portion in the preform, and there is also variation between shots, which may limit the freedom in designing the shape of the window portion, or may make the boundary between the peripheral wall made of opaque resin and the window portion made of transparent or translucent resin unclear. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-108796 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have conducted extensive research in order to provide a synthetic resin container having a light-shielding layer through which the liquid contained therein can be visually observed, and as a result have completed the present invention. [Means for solving the problem]

[0007] 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-like shape along the axial direction, and including a light-transmitting layer in which one or more thick-walled portions are formed parallel to the protrusion, on the radially opposite side to the position at which the protrusion is formed, and a light-shielding layer which is laminated on the side of the light-transmitting layer on which the protrusion is formed, the portion overlapping the protrusion being partially missing, and the portion which overlaps the thick-walled portion covering the thick-walled portion.

[0008] Furthermore, the synthetic resin container of the present invention comprises a mouth portion which serves as an injection outlet for the content liquid, and a storage portion in which the internal solution is stored, and the storage portion is configured to include a light-transmitting layer on which a band-like protrusion portion extending along the axial direction is formed, and on the radially opposite side to the position at which the protrusion portion is formed, one or more thick-walled portions are formed parallel to the protrusion portion, and a light-shielding layer which is laminated on the side of the light-transmitting layer on which the protrusion portion is formed, is partially missing at the portion which overlaps the protrusion portion, and covers the thick-walled portion at the portion which overlaps the thick-walled portion. Effect of the Invention

[0009] According to the present invention, it is possible to provide a synthetic resin container having a light-shielding layer through which the liquid contained therein can be visually confirmed, and a preform for blow molding such a container. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view showing an outline of a synthetic resin container according to a first embodiment of the present invention. [Diagram 2]1 is a front view showing an outline of a synthetic resin container according to a first embodiment of the present invention. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 2 is an explanatory view showing an example of a preform according to the first embodiment of the present invention. [Diagram 5] 5 is a cross-sectional view of FIG. 4 taken along line B-B. [Figure 6] 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. [Figure 7] 7 is a cross-sectional view taken along CC in FIG. 6. [Figure 8] FIG. 4 is an explanatory view showing a modified example of the preform according to the first embodiment of the present invention. [Figure 9] FIG. 9 is a cross-sectional view taken along the line DD in FIG. [Figure 10] 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. [Figure 11] FIG. 11 is an explanatory view showing another modified example of the preform according to the first embodiment of the present invention. [Figure 12] 12 is a cross-sectional view of FIG. 11 taken along line E-E. [Figure 13] 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. [Figure 14] 4 is a front view showing an outline of a synthetic resin container according to a second embodiment of the present invention. FIG. [Figure 15] 15 is a cross-sectional view of FIG. 14 . [Figure 16] FIG. 4 is an explanatory view showing an example of a preform according to a second embodiment of the present invention. [Figure 17] FIG. 17 is a cross-sectional view of FIG. [Figure 18] FIG. 11 is an explanatory view showing another example of a synthetic resin container according to the present invention. [Figure 19] FIG. 11 is an explanatory view showing another example of a synthetic resin container according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0012] [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 AA 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.

[0013] The container 1 shown in these figures has a mouth 2 which serves as an inlet / outlet for the content liquid, 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 in the figures, the container 1 is molded to have a generally cylindrical container shape, but the shape of the container 1 is not limited to this.

[0014] Here, the height direction refers to the direction perpendicular to the horizontal plane when container 1 is placed upright on the horizontal plane with mouth 2 facing up, and the up-down, left-right and length-width directions of container 1 are defined as shown in Figure 2 when container 1 is placed upright with mouth 2 facing up.

[0015] 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, on the lower end side of the mouth portion 2, there is provided an annular neck ring 2b that protrudes outward in the circumferential direction.

[0016] 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 protrusion 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 protrusion 6 is formed, and is partially missing at a portion overlapping the protrusion 6, thereby reducing the light-shielding property at that portion. As a result, the content liquid can be visually confirmed through that portion where the light-shielding property is reduced, and for example, when refilling the content liquid into the container 1, an appropriate amount of content liquid can be refilled while visually checking the liquid level of the content liquid so that the content liquid does not overflow.

[0017] 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 FIG. 3). Although not particularly shown, the light-shielding layer may be partially removed so that the thickness of the light-shielding layer 3b is thinner at the portion overlapping the protrusion 6, as long as the light-shielding properties can be reduced to an extent that the contents can be visually confirmed.

[0018] In this embodiment, the container 1 can be molded into a predetermined container shape, for example, by blow molding a preform 10 as shown in FIG.

[0019] FIG. 4 shows an example of a preform 10 for blow molding a container 1, and the preform 10 is formed in a bottomed cylindrical shape having a mouth portion 20 formed on the upper end side and a body portion 30 that is closed in a semispherical shape on the lower end side.

[0020] 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. FIG. 5 is a cross-sectional view taken along line B-B of FIG. 4, but the thicknesses shown in the cross-section are exaggerated and do not reflect the actual dimensions.

[0021] The mouth portion 20 of the preform 10 is a portion that will become the mouth portion 2 of the container 1 without being stretched by blow molding and will generally maintain its appearance, and the mouth portion 20 of the preform 10 is provided with an engaging protrusion 2a and a neck ring 2b 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 portion 30 starting from below the neck ring 2b provided on the mouth portion 20 and molding it to become the storage portion 3 of the container 1.

[0022] In the example shown in Fig. 4, the body 30 of the preform 10 is formed to include a light-transmitting layer 30a molded on the light-transmitting layer 3a that forms the storage section 3 of the container 1, and a light-shielding layer 30b molded on the light-shielding layer 3b, which are integrally blow-molded. The light-transmitting layer 30a is formed with a strip-like protrusion 60 extending along the axial direction, and the protrusion 60 is formed to become the protrusion 6 formed on 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 light-shielding layer 30b is partially deleted at the portion overlapping the protrusion 60 formed on the light-transmitting layer 30a (see Fig. 5), and such a 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.

[0023] A resin material for forming the light-transmitting layer 30a (i.e., a resin material for forming the light-transmitting layer 3a) may 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 may be used, and in particular, an ethylene terephthalate-based thermoplastic polyester such as polyethylene terephthalate may be preferably used.

[0024] In addition, as the resin material for forming the light-shielding layer 30b (i.e., the resin material for 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 foamed structure formed by foaming the foamable resin as described below.

[0025] Such a preform 10 can be molded by an injection molding method called two-color molding or double molding, for example, as follows.

[0026] 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 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. FIG. 7 is a cross-sectional view taken along line CC of FIG. 6, but the thicknesses shown in the cross-section are exaggerated and do not reflect the actual dimensions.

[0027] Next, instead of the primary body mold 202a, a secondary body mold 202b configured to form a gap for molding the light-shielding layer 30b between the molded preform intermediate 10a is used, and the mold is clamped again, and then a resin material for forming 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. When a foamable resin is used as the resin material for forming the light-shielding layer 30b, it is preferable from the viewpoints of light-shielding properties and appearance to maintain a high pressure inside the cavity and inject the resin while maintaining the pressure so that the foamable resin can be prevented from breaking during its flow and from foaming after filling.

[0028] By undergoing such primary injection process and secondary injection process, a preform 10 can be molded which has a body 30 including a light-transmitting layer 30a on which a protrusion 60 extending in a band-like shape along the axial direction is formed, and a light-shielding layer 30b which is laminated on the side of the light-transmitting layer 30a on which the protrusion 60 is formed and has a portion overlapping the protrusion 60 partially missing.

[0029] Here, if the protrusion 60 formed on the light-transmitting layer 30a is a single strip, the resin pressure when the resin material is injected into the cavity in the primary injection process will not act evenly in the circumferential direction on the core mold 200, and the core mold 200 will be pushed from the side where the protrusion 60, which has a relatively large amount of resin, is formed, and will become tilted, which may result in uneven thickness in the molded preform intermediate 10a.

[0030] In this embodiment, in order to effectively avoid such a problem, it is preferable to form a plurality of protrusions 60 (two in the illustrated example) on the light-transmitting layer 30a and arrange them symmetrically with respect to the central axis. This allows 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 to cancel each other out, preventing the core mold 200 from tilting.

[0031] As long as the inclination of the core die 200 can be effectively prevented against the resin pressure acting on the core die 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, for example, 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 die 200 from the side where the protrusions 60 are formed, in other words, the amount of resin forming the protrusions 60. 9 is a DD cross-sectional view 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 E-E cross-sectional view of FIG 11 shown in FIG 12.

[0032] 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), and while being stretched in the axial direction (longitudinal direction) by a stretching rod as necessary, it is stretched in the axial and circumferential directions (lateral directions) by blow 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 to the body 30, so that the stretched body 30 is molded to become the container 3 of the container 1.

[0033] 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 by 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 property can be expressed by the foamed structure.

[0034] By blow molding the preform 10 in this manner, a container 1 as described above in which the liquid content can be visually confirmed can be formed. When a preform 10 is used in which a plurality of protrusions 60 are formed in the light-transmitting layer 30a so as to be arranged symmetrically about the central axis, a plurality of protrusions 6 will be formed symmetrically about the central axis in the light-transmitting layer 3a of the molded container 1 (see FIG. 3).

[0035] Furthermore, when a preform 10 is used in which one or more thick portions 60a are formed parallel to the protrusion 60 on the radially opposite side of the position where the protrusion 60 is formed, as in the modified example shown in Figures 8 and 9, or another modified example shown in Figures 11 and 12, one or more thick portions 6a are formed parallel to the protrusion 6 on the radially opposite side of the position where the protrusion 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 cross-section AA 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.

[0036] 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 has translucency so that the liquid level of the content liquid can be visually confirmed even through the mouth portion 2. According to this embodiment, in the primary injection step of injection molding the preform 10 as described above, the mouth portion 20 and the translucent layer 30a are integrally molded using a resin material that forms the translucent layer 30a, thereby making it possible to mold the preform 10 having the translucent mouth portion 20. Therefore, in the container 1 obtained by blow molding the preform 10, the mouth portion 2 can be molded to have translucency.

[0037] [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 an E-E cross-sectional view 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.

[0038] In the first embodiment described above, the storage section 3 of the container 1 is configured such that the light-transmitting layer 3a on which the protrusions 6 extending in a strip 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 protrusions 6 are formed and is partially missing at the portion overlapping the protrusions 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 such 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.

[0039] FIG. 13 shows an example of a preform 10 for blow molding a container 1 in this embodiment, in which the preform 10 is molded integrally with the mouth portion 20, with the light-shielding layer 30b partially missing at a portion overlapping with the protrusion portion 60 formed in the light-transmitting layer 30a located on the outer layer side, and is configured such that the protrusion portion 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.

[0040] Such a preform 10 can be molded in the same manner as described in the first embodiment, but in the first injection step of injection molding the preform intermediate 10a, the mouth portion 20 and the light-shielding layer 30b are molded integrally with the resin material that forms the light-transmitting layer 30a. Then, in the second injection step, the light-transmitting layer 30a is injection molded.

[0041] The preform 10 thus molded can be molded into a container 1 by being set in a blow mold after a heat treatment and blow molding in the same manner as in the first embodiment, but in this embodiment, the mouth portion 20 of the preform 10 is molded integrally with the light-shielding layer 30b. For this reason, when a foamable resin is used as the resin material for forming the light-shielding layer 30b, the mouth portion 20 is also formed of the foamable resin. Even in this case, when the preform 10 is heated prior to the blow molding, the mouth portion 20 is covered with a shielding body, for example, so that the body portion 30 is selectively heated, and the foamable resin forming the light-shielding layer 30b is foamed while preventing the foamable resin forming the mouth portion 20 from foaming, thereby changing the internal structure of the light-shielding layer 30b so as to have a foamed structure containing a large number of bubbles formed thereby. Furthermore, by making the mouth portion 20 of the preform 10 non-foamed, the mouth portion 2 of the container 1 obtained by blow molding the preform 10 can be molded to have translucency, as in the first embodiment, and it is also possible to improve the visibility of the liquid level of the content liquid.

[0042] As described above, this embodiment differs from the first embodiment in the above points, but other configurations are common to the first embodiment, so duplicated explanations of the configurations common to the first embodiment will be omitted.

[0043] Although the present invention has been described above by showing preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

[0044] 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 container 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 container 3 and the remaining amount of the liquid content visible on the lower side of the container 3. Furthermore, as shown in FIG. 16, the light-shielding layer 3b can be formed in the range excluding the upper side of the container 3 so that the liquid level of the liquid content can be better seen on the upper side of the container 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. [Explanation of symbols]

[0045] 1 container 2 Mouth 3. Storage section 3a Translucent layer 3b Light blocking layer 6 Projection part 6a Thick part 10 Preform 20 Mouth 30 Torso 30a Translucent layer 30b Shade layer 60 Projection part 60a thick part

Claims

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

2. 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.

Images