JP5397761B2 - Plastic bottle - Google Patents

Description

  The present invention relates to a plastic bottle provided with a mouth, a shoulder, a trunk, and a bottom.

  In recent years, it has been desired to reduce the weight of plastic bottles by reducing the amount of plastic material used in the plastic bottles. However, when the bottle is lightened, the strength of the bottle is weakened. For this reason, in order to maintain a certain strength, the light weight bottle has restrictions such as being limited to design and sales at stores (hand sale).

  Also, when bottles are sold in vending machines, the bottles in the vending machine tend to be laid sideways and loaded, so that the bottles in the lower tier tend to be crushed. There is a tendency that the bottle cannot be discharged or the bottle is recessed during storage or discharge in the vending machine. In order to solve this, there is a technique of filling a bottle with liquid nitrogen or the like immediately after the bottle is filled with the content liquid in the process of manufacturing the bottle beverage, thereby positively increasing the bottle internal pressure and closing the bottle. Thereby, the inside of a bottle becomes a positive pressure and it is possible to raise the intensity | strength of a bottle. In addition, filling the inside of the bottle with an inert gas such as nitrogen as described above also has an effect of preventing the content liquid (for example, green tea) from being oxidized.

  Further, when natural foaming water (sparkling water) or oxygen water is filled in the bottle, the inside of the bottle is slightly positive. Alternatively, if the bottle is filled with content liquid such as green tea or coffee and the filling temperature is lower than the selling temperature, the volume of the inner solution expands by increasing the temperature difference between the selling and filling, and the inside of the bottle expands. Positive pressure.

  In this way, plastic bottles with positive pressure inside (positive pressure bottles) need to have pressure resistance, and it is necessary to minimize container deformation during pressurization. There are constraints. As a result, there is one aspect that the design property tends to be poor. For example, when a plastic bottle is in a pressurized state, the bottom of the bottle may be inverted, so the bottom is often formed into a petaloid shape. In addition, since the body of the bottle expands, there is a restriction that it is difficult to give a special shape such as a panel to the body.

  For this reason, many conventional pressure resistant (including positive pressure) bottles have a petaloid shape at the bottom and a barrel or relatively plain shape at the barrel. Therefore, many conventional pressure resistant (including positive pressure) bottles have poor design.

JP 7-125737 A JP 2007-62800 A

  For example, as in Patent Documents 1 and 2, some conventional pressure-resistant bottles are provided with a constricted structure in the body. However, in order to maintain the constricted shape even when pressurized, it is necessary to increase the thickness of the container. For this reason, it is difficult to reduce the weight of the bottle.

  Thus, when trying to reduce the weight of the pressure-resistant bottle, it is necessary to take measures against body swelling. Also, once the bottle is opened, the strength on the side of the bottle is remarkably reduced.

  The present invention has been made in consideration of such points, and an object of the present invention is to provide a plastic bottle that is easy to hold in both cases of pressure-sealing and opening and is excellent in design. .

  The present invention relates to a plastic bottle having a mouth portion, a shoulder portion, a body portion, and a bottom portion. The body portion includes an upper constriction region and a lower constriction region connected to the upper constriction region via a small-diameter annular line. The upper constriction region and the lower constriction region both consist of a number of planar triangular panels partitioned by ridge lines, and when the pressure inside the plastic bottle is pressurized to 1 kPa to 400 kPa, Each triangular panel expands to form a convex surface that protrudes outward, and a curved surface is formed in the vicinity of the ridgeline between the triangular panels. When the plastic bottle is opened, each triangular panel returns to a flat shape. A plastic bottle characterized by maintaining the strength of the constricted area.

  In the present invention, the upper constriction region and the lower constriction region both have a structure in which a downward downward triangular panel whose bottom is upward and an upward upward triangular panel whose bottom is downward are alternately arranged in the circumferential direction. It is a plastic bottle characterized by becoming.

  According to the present invention, the downward triangular panel and the upward triangular panel in the upper constricted region and the lower constricted region are adjacent to each other via a ridge line, and the downward triangular panel and the upward triangular panel are both a pair of base angle and apex angle. The plastic bottle is characterized in that it has the same shape and the base angle of one of the pair of base angles is 90 ° or more.

  The present invention is the plastic bottle characterized in that in the upper constricted region and the lower constricted region, the downward triangular panel and the upward triangular panel are each composed of a non-symmetric triangle.

  The present invention is the plastic bottle characterized in that the small-diameter annular line has a regular polygonal horizontal cross section.

  The present invention is the plastic bottle characterized in that the bottom portion has a plurality of legs projecting downward.

The present invention is characterized in that the ratio (d ₁ / d ₂ ) of the diameter d ₁ of the constricted region in the small-diameter annular line to the maximum diameter d ₂ of the trunk is 0.60 or more and 0.95 or less. It is a plastic bottle.

  The present invention is the plastic bottle characterized in that the total number of triangular panels in the constricted region is 32 or more and 96 or less.

  The present invention is the plastic bottle characterized in that the thickness of the constricted region is 0.07 mm to 0.40 mm.

  According to the present invention, when the inside of a plastic bottle is pressurized to a pressure of 1 kPa to 400 kPa, each triangular panel expands to form a convex surface protruding outward, and a curved surface near the ridge line between the triangular panels. Is formed. As a result, when the inside is sealed with a positive pressure, the horizontal section of the constricted region approaches a circle, so that the feel when grasping the bottle can be made smooth and easy to hold. In addition, when the plastic bottle is opened, each triangular panel returns to a planar shape, and the strength of the constricted area is maintained. At this time, since the horizontal cross section of the constricted area is restored from the substantially circular shape to the original shape after opening, the strength of the body portion is maintained, and the stability when holding the plastic bottle can be increased.

FIG. 1 is a front view showing a plastic bottle according to an embodiment of the present invention. FIG. 2 is an enlarged front view showing a constricted region of a plastic bottle according to an embodiment of the present invention. FIG. 3 is a sectional view showing a plastic bottle according to an embodiment of the present invention (a sectional view taken along line III-III in FIG. 1). FIG. 4 is a sectional view showing a plastic bottle according to an embodiment of the present invention (a sectional view taken along line IV-IV in FIG. 1). FIG. 5 is a cross-sectional view showing a plastic bottle according to an embodiment of the present invention (a cross-sectional view taken along line VV in FIG. 1). FIG. 6 is a front view showing a plastic bottle according to an embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 show an embodiment of the present invention.

  First, the outline of the plastic bottle according to the present embodiment will be described with reference to FIGS. In the present specification, “upper” and “lower” refer to the upper and lower sides of the plastic bottle 10 in an upright state (FIG. 1), respectively.

  As shown in FIG. 1, the plastic bottle 10 includes a mouth portion 11, a shoulder portion 12, a trunk portion 20, and a bottom portion 30.

  Of these, the body portion 20 includes an upper cylindrical portion 21 connected to the shoulder portion 12 and a lower cylindrical portion 22 connected to the bottom portion 30. The upper cylindrical portion 21 is provided with a plurality of annular reinforcing grooves 21a. Further, a constricted region 23 that is recessed inward of the bottle is formed between the upper cylindrical portion 21 and the lower cylindrical portion 22.

  The constricted region 23 includes an upper constricted region 24 and a lower constricted region 26 connected to the upper constricted region 24 through a small-diameter annular line 25. The small-diameter annular line 25 has a minimum circumferential length of the body portion 20. Further, the upper constriction region 24 gradually increases in circumferential direction length from the small-diameter annular line 25 upward, and the lower constriction region 26 gradually increases in circumferential direction length from the small-diameter annular line 25 downward. .

  Further, an upper annular line 27 is formed between the upper constriction region 24 and the upper cylindrical portion 21 over the entire circumferential direction, and between the lower constriction region 26 and the lower cylindrical portion 22, the lower circumferential portion extends downward. An annular line 28 is formed.

  Each of the upper constricted region 24 and the lower constricted region 26 is composed of a large number of planar triangular panels 24a, 24b, 26a, 26b divided by ridgelines 24c, 24d, 26c, 26d.

  The total number of triangular panels constituting the constricted region 23 is preferably 32 or more and 96 or less, and more preferably 60 or more and 72 or less. In the present embodiment, 16 triangular panels 24a, 24b, 26a, and 26b are provided, for a total of 64. When the total number of triangular panels is less than 32, the constricted region 23 is swollen when the inside of the bottle is pressurized or depressurized, which is not preferable. On the other hand, when the total number of triangular panels exceeds 96, the plastic bottle 10 will cause shaping defects.

  That is, as shown in FIG. 2, the upper constricted region 24 has a structure in which downward triangular panels 24a having bottoms facing upward and upward triangular panels 24b having bottoms facing downwards are alternately arranged in the circumferential direction. It is made up of. The bottom side of each downward triangular panel 24 a is located on the upper annular line 27. On the other hand, the bottom side of each upward triangular panel 24 b is located on the small-diameter annular line 25.

  Similarly, the lower constricted region 26 has a structure in which downward triangular panels 26a with bottoms facing upward and upward triangular panels 26b with bottoms facing downwards are alternately arranged in the circumferential direction. The bottom side of each downward triangular panel 26 a is located on the small diameter annular line 25. On the other hand, the base of each upward triangular panel 26 b is located on the lower annular line 28.

  Further, in each of the upper constricted region 24 and the lower constricted region 26, the downward triangular panels 24a, 26a and the upward triangular panels 24b, 26b are all adjacent to each other via ridge lines 24c, 24d, 26c, 26d. Each of the downward triangular panels 24a and 26a and the upward triangular panels 24b and 26b has valley-like ridgelines 24c and 26c that are convex toward the inside and mountain-shaped ridgelines 24d and 26d that are convex toward the outside, except for the base. .

  That is, as shown in FIG. 2, in the upper constricted region 24, each downward triangular panel 24 a is adjacent to the upward triangular panel 24 b on one side (left side in FIG. 2) via the valley-shaped ridge line 24 c. Each downward triangular panel 24a is adjacent to the upward triangular panel 24b on the other side (right side in FIG. 2) via a mountain-shaped ridge line 24d.

  Similarly, in the downward constricted region 26, each downward triangular panel 26a is adjacent to the upward triangular panel 26b on one side (the left side in FIG. 2) via a valley-shaped ridge line 26c. Each downward triangular panel 26a is adjacent to the upward triangular panel 26b on the other side (right side in FIG. 2) via a mountain-shaped ridge line 26d.

  Therefore, as shown in FIGS. 3 and 4, the horizontal cross section of the constricted region 23 in the upper constricted region 24 and the lower constricted region 26 has a star shape (32-square shape). On the other hand, as shown in FIG. 5, the horizontal cross section of the constricted region 23 in the small-diameter annular line 25 is a regular polygon (regular hexagon).

  With this configuration, when the inside of the bottle is pressurized, a force is applied to the surfaces of the triangular panels 24a, 24b, 26a, and 26b, so that the direction of the force can be made uniform in the circumferential direction. Thereby, the constriction area | region 23 can be made difficult to deform | transform.

  3 to 5, the solid line indicates a horizontal cross section of the constricted region 23 in a state where the inside of the bottle is not pressurized, and the imaginary line (two-point difference line) indicates the positive pressure (1 kPa to 400 kPa) inside the bottle. The horizontal cross section of the constriction area | region 23 in the state made into the is shown.

As shown in FIGS. 3 to 5, when the inside of the bottle is pressurized to a positive pressure (a pressure of 1 kPa to 400 kPa), each triangular panel 24a, 24b, 26a, 26b expands and protrudes outward. Convex surfaces 24a ₁ , 24b ₁ , 26a ₁ and 26b ₁ are formed. As a result, curved surfaces 24e, 24f, 26e, and 26f are formed in the vicinity of the ridgelines 24c, 24d, 26c, and 26d between the triangular panels 24a, 24b, 26a, and 26b, respectively.

  Specifically, in FIG. 3, a curved surface 24e recessed inward is formed in the vicinity of the valley-shaped ridgeline 24c. In addition, a curved surface 24f protruding outward is formed in the vicinity of the mountain-shaped ridge line 24d. Similarly, in FIG. 4, a curved surface 26e recessed inward is formed in the vicinity of the valley-shaped ridge line 26c. Further, a curved surface 26f protruding outward is formed in the vicinity of the mountain-shaped ridge line 26d.

  On the other hand, as shown in FIG. 5, when the inside of the bottle is set to a positive pressure (1 kPa to 400 kPa), the small-diameter annular line 25 slightly swells outward, and its horizontal cross section approaches a circle. That is, each side 25a of the regular polygon (regular hexagon) constituting the small-diameter annular line 25 is curved and swells by about 1% to 5% at the container expansion rate.

  The horizontal cross section of the small-diameter annular line 25 is preferably a regular octagon to a regular 24 square, and more preferably a regular dodecagon to a regular decagon. If the horizontal cross section of the small-diameter annular line 25 is a heptagon or less, when the inside of the bottle is pressurized, the constriction diameter increases by 5 mm or more, and the constriction region 23 is less likely to cause reversible deformation. On the other hand, when the horizontal cross section of the small-diameter annular line 25 is 25 squares or more, there is a risk of poor shaping.

Further, as shown in FIG. 6, when the diameter of the constriction region 23 in the small-diameter annular line 25 is d ₁ and the maximum diameter of the body portion 20 is d ₂ , the diameter d ₁ of the constriction region 23 is the maximum of the body portion 20. The ratio (d ₁ / d ₂ ) to the diameter d ₂ is preferably 0.60 or more and 0.95 or less (0.60 ≦ d ₁ / d ₂ ≦ 0.95), and is set to about 0.85. Most preferred. In addition, when this ratio (d ₁ / d ₂ ) is less than 0.60 (0.60> d ₁ / d ₂ ), there is a risk of forming defects during blow molding. On the other hand, when this ratio (d ₁ / d ₂ ) exceeds 0.95 (d ₁ / d ₂ > 0.95), the plastic bottle 10 may be difficult to hold, and in terms of grip properties (UD suitability). It is not preferable.

Further, as shown in FIG. 6, when the height from the ground contact surface of the bottom 30 to the small-diameter annular line 25 is h ₁ and the total height of the plastic bottle 10 is h ₂ , the height h ₁ to the small-diameter annular line 25 is Of the total height h ₂ of the plastic bottle 10 (h ₁ / h ₂ ) is preferably 0.20 or more and 0.60 or less (0.20 ≦ h ₁ / h ₂ ≦ 0.60), More preferably, it is about 0.30. If this ratio (h ₁ / h ₂ ) is less than 0.20 (0.20> h ₁ / h ₂ ), the plastic bottle 10 may be difficult to hold. ) Is not preferable. On the other hand, when this ratio (h ₁ / h ₂ ) exceeds 0.60 (h ₁ / h ₂ > 0.60), blow moldability may be deteriorated.

  Referring to FIG. 2 again, in each of the upper constricted region 24 and the lower constricted region 26, the downward triangular panels 24a and 26a and the upward triangular panels 24b and 26b are each formed of a non-axisymmetric triangle.

Here, referring to FIG. 2, the downward triangular panel 24a of the upper constricted area 24 will be described as an example. The plurality of downward triangular panels 24a have the same shape. Each downward triangular panel 24a has a pair of base angles θ ₁ , θ ₂ and a vertex angle θ ₃ . Of the pair of base angles θ ₁ and θ ₂ of each downward triangle panel 24a, one base angle θ ₁ is 90 ° or more. Therefore, the mountain-shaped ridge line 24d constituting each downward triangular panel 24a is inclined outward, and the valley-shaped ridge line 24c is inclined inward.

  Similarly, the upward triangular panels 24b, the downward triangular panels 26a, and the upward triangular panels 26b all have the same shape having a pair of base angles and apex angles. In addition, one of the pair of base angles of the triangular panels 24b, 26a, and 26b has a base angle of 90 ° or more.

  By the way, as shown in FIG. 1, the bottom part 30 of the plastic bottle 10 has comprised what is called a petaloid bottom shape. That is, the bottom portion 30 has a plurality (five in the present embodiment) of leg portions 31 that are arranged at equal intervals in the circumferential direction and project downward.

  The number of the leg portions 31 can be 5 to 9. However, the number of the leg portions 31 is most preferably 5 to 7 from the viewpoint of stably erecting the plastic bottle 10 and improving the moldability of the lightweight bottle.

  The size (capacity) of such a plastic bottle 10 is not limited, and may be made of any size bottle. The wall thickness of the plastic bottle 10 can be set to 0.07 mm to 0.40 mm in the constricted region 23, whereby the weight of the plastic bottle 10 can be reduced.

  Such a plastic bottle 10 can be produced by biaxially stretch blow molding a preform produced by injection molding a synthetic resin material. In addition, it is preferable to use a thermoplastic resin, especially PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate) as a material of the preform, that is, the plastic bottle 10.

  The plastic bottle 10 can also be formed as a multilayer molded bottle having two or more layers. That is, by extrusion molding or injection molding, for example, the intermediate layer has gas barrier properties and light shielding properties such as MXD6, MXD6 + fatty acid salt, PGA (polyglycolic acid), EVOH (ethylene vinyl alcohol copolymer) or PEN (polyethylene naphthalate). A multilayer bottle having gas barrier properties and light shielding properties may be formed by extrusion molding a preform composed of three or more layers as the resin (intermediate layer), and then blow molding. Such an intermediate layer is preferably provided in at least the body 20 of the plastic bottle 10. Further, it is preferable to provide an intermediate layer in the region of the bottom portion 30 excluding the central portion of the bottom portion 30. This is because this portion may cause delamination (delamination) when subjected to an impact such as a case dropping. In order to have gas barrier properties and light-shielding properties, blend bottles, coating bottles and vapor deposition bottles in which thermoplastic resins are blended may be used as well as multilayers.

  The object to be filled in the plastic bottle 10 is not limited, but the bottle internal pressure is positiveized with carbonated drinking water, natural foaming water (sparkling water), oxygen water, liquid nitrogen, etc., in which the inside of the plastic bottle 10 becomes positive pressure after filling. Soft drinks are suitable. Here, the positive pressure inside the plastic bottle 10 means that the internal pressure of the plastic bottle 10 becomes 1 kPa to 400 kPa when the liquid temperature of the filled content liquid is 20 ° C. In particular, when the internal pressure of the plastic bottle 10 is 1 kPa to 150 kPa, the effect of the present embodiment is easily obtained.

  Next, the operation of the present embodiment having such a configuration will be described.

  First, the plastic bottle 10 is filled with a content liquid such as carbonated drinking water, natural foaming water (sparkling water), oxygen water, green tea, or coffee, and then liquid nitrogen is filled into the head space and then closed. At this time, the inside of the plastic bottle 10 becomes a positive pressure (for example, when the liquid temperature of the content liquid is 20 ° C., the internal pressure immediately after filling is 1 kPa to 400 kPa) due to the filled inert gas or the content liquid.

  When the inside of the plastic bottle 10 becomes a positive pressure, a force acts from the inside of the plastic bottle 10 to the outside, and pressure is applied to the body portion 20 from the inside in the radial direction to the outside. In this state, the plastic bottle 10 (beverage product) filled with the contents is shipped, transported to a retail store or put into a vending machine and sold to consumers.

At this time, when the inside of the plastic bottle 10 becomes positive pressure, the triangular panels 24a, 24b, 26a, 26b of the constricted region 23 expand and project outwardly projecting surfaces 24a ₁ , 24b ₁ , 26a ₁ , 26b ₁ is formed. Accordingly, curved surfaces 24e, 24f, 26e, and 26f are formed in the vicinity of the ridge lines 24c, 24d, 26c, and 26d, respectively. In this way, the triangular panels 24a, 24b, 26a, and 26b slightly bulge outward, so that the horizontal section of the constricted region 23 approaches a circle (see the phantom lines in FIGS. 3 to 5). As a result, the feel when gripping the constricted area 23 becomes smooth, and it fits in the hand and is easy to hold. On the other hand, since the constricted region 23 is not greatly deformed, it is possible to maintain a designable body shape even when the inside of the bottle is set to a positive pressure.

After being sold, the consumer opens the beverage product to drink. At this time, the internal pressure of the plastic bottle 10 is reduced to atmospheric pressure. At this time, each triangular panel 24a, 24b, 26a, 26b returns to the original planar shape from the state bulging outward (that is, the convex surfaces 24a ₁ , 24b ₁ , 26a ₁ , 26b ₁ ). As a result, the constricted region 23 is also restored to the original shape. Specifically, the horizontal cross section of the upper constricted region 24 and the lower constricted region 26 is restored to a star shape (see solid lines in FIGS. 3 and 4), and the horizontal cross section of the small-diameter annular line 25 is restored to a regular polygon shape. (See the solid line in FIG. 5). Thus, since the strength of the constricted region 23 is maintained by restoring the constricted region 23 to the original shape, a sense of stability when the plastic bottle 10 is gripped after opening is increased. In particular, even when the plastic bottle 10 is opened after a long period of time (for example, several months or more) has passed after sealing, the constricted region 23 is stably restored to the original shape.

  As described above, according to the present embodiment, even when the plastic bottle 10 is formed thin and the inside thereof is set to a positive pressure, it is possible to maintain a designable body shape, and the plastic bottle 10 10 ease of holding (grip property) can be maintained. On the other hand, after opening, the horizontal cross section of the constricted region 23 is restored to its original shape, so that the strength of the body portion 20 is maintained and the plastic bottle 10 can be stably held.

  Further, according to the present embodiment, the upper constricted region 24 and the lower constricted region 26 each have a structure in which downward triangular panels 24a and 26a and upward triangular panels 24b and 26b are alternately arranged in the circumferential direction. . Further, the downward triangular panels 24a, 26a and the upward triangular panels 24b, 26b are all adjacent to each other via the ridgelines 24c, 24d, 26c, 26d. The downward triangular panels 24a and 26a and the upward triangular panels 24b and 26b all have the same shape having a pair of base angles and apex angles, and one of the pair of base angles has a base angle of 90 ° or more. . Furthermore, the downward triangle panels 24a and 26a and the upward triangle panels 24b and 26b are each composed of a non-axisymmetric triangle. By these things, the effect (design property, grip property, restoring property) mentioned above can further be improved.

  Furthermore, none of the ridgelines 24c, 24d, 26c, and 26d are oriented in the horizontal direction. Therefore, even when the inside of the plastic bottle 10 is set to a positive pressure, the constriction region 23 is unlikely to expand in the height direction, so that a change in the overall height of the plastic bottle 10 can be suppressed to be small.

  Furthermore, according to the present embodiment, since the small-diameter annular line 25 has a regular polygonal horizontal section, the direction of the force applied to the constricted region 23 can be made uniform in the circumferential direction when the inside of the bottle is pressurized. The constricted region 23 can be made difficult to deform.

  Next, specific examples in the present embodiment will be described.

  First, the following three types of plastic bottles (Example 1, Comparative Example 1, and Comparative Example 2) were prepared.

Example 1
A plastic bottle 10 (Example 1) for 500 ml having the configuration shown in FIGS. 1 to 6 was produced. In this case, the plastic bottle 10 (Example 1) was produced by carrying out biaxial stretch blow molding of 18g preform. In Example 1, the ratio (d ₁ / d ₂ ) of the diameter d ₁ (58 mm) of the constricted region 23 to the maximum diameter d ₂ (68 mm) of the body portion 20 was 0.85. This plastic bottle 10 (Example 1) is made thinner than a plastic bottle generally used conventionally. In Example 1, as described above, the total number of triangular panels was 64.

(Comparative Example 1)
A plastic bottle for 500 ml (Comparative Example 1) having a constricted region 23 having a plain structure was produced. The plastic bottle of Comparative Example 1 has the same weight and thickness as Example 1.

(Comparative Example 2)
A plastic bottle for 500 ml (Comparative Example 2) having a constricted region 23 having a plain structure was produced. In Comparative Example 2, a plastic bottle (Comparative Example 2) was produced by biaxially stretching blow molding a 28 g preform. That is, the plastic bottle of Comparative Example 2 is heavier than the plastic bottle 10 of Example 1. The plastic bottle (Comparative Example 2) has a thickness 1.5 to 4 times that of the plastic bottle 10 of Example 1.

(Investigation of changes in container dimensions before and after pressurization)
With respect to the three types of plastic bottles (Example 1, Comparative Example 1, and Comparative Example 2), the container expansion rate was measured when the inside of the bottle was set to a positive pressure.

  Specifically, first, the container full volume of each plastic bottle in an empty state was measured, and then the inside of each plastic bottle was sealed with a positive pressure (50 kPa). In this state, each plastic bottle was stored at 22 ° C. for 9 months, and then the container full volume of each plastic bottle in a sealed state was measured. Subsequently, the container expansion rate (%) of each plastic bottle was calculated (see Table 1). The container expansion rate (%) is determined by the formula {(container full volume in a sealed state) / (container full volume in an empty state) -1} × 100.

  As a result, although the plastic bottle 10 of Example 1 was lighter than the plastic bottle of Comparative Example 2, the container expansion rate could be kept relatively low. From this, it is thought that the plastic bottle 10 of Example 1 is a container with a high restoring force.

(Ease of holding)
Next, the ease of holding was evaluated for each of the three types of plastic bottles (Example 1, Comparative Example 1, and Comparative Example 2). Specifically, panelists of 40 men and women aged 20 to 40 years old were asked to evaluate the ease of holding at the time of pressure sealing and the ease of holding after opening for each of the three types of plastic bottles. In this case, the bottle of Comparative Example 2 at the time of pressurization and sealing was used as a reference (5.0 points), and evaluation was performed in five stages by a deduction method. The average of each evaluation value at this time was as follows (see Table 2).

  As a result, the plastic bottle 10 of Example 1 is highly evaluated for both men and women, especially when it is opened. When compared with the plastic bottle of Comparative Example 1, it can be seen that the evaluation is particularly high from men with strong grip strength.

(Eye-catch study)
Next, the eye catching property of each of the plastic bottle 10 of Example 1 and the plastic bottle of Comparative Example 1 was investigated. Specifically, both of these two types of plastic bottles were first displayed on a merchandise display shelf. Next, for panelists of 40 men and women aged 20 to 40 years old, each panelist first determined that the bottle shape was higher in eye-catching (consumer purchasing motivation) (see Table 3). ). In addition, since the plastic bottle of the comparative example 1 and the plastic bottle of the comparative example 2 differ only in thickness, the plastic bottle of the comparative example 2 was excluded from object.

  As a result, it has been found that the plastic bottle 10 of Example 1 has a shape that is overwhelmingly conspicuous (high eye catching property).

DESCRIPTION OF SYMBOLS 10 Plastic bottle 11 Mouth part 12 Shoulder part 20 Trunk part 21 Upper cylindrical part 21a Reinforcing groove 22 Lower cylindrical part 23 Constriction area | region 24 Upper constriction area | region 24a, 26a Downward triangular panel 24b, 26b Upward triangular panel 24c, 26c Valley-like ridgeline 24d, 26d mountain-shaped ridge 24e, 24f, 26e, 26f curved surface _{24a 1, 24b 1, 26a 1} , 26b 1 convex surface 25 diameter annular line 25a side 26 downward constricted region 27 upper annular line 28 lower annular line 30 bottom 31 leg

Claims (9)

In a plastic bottle with a mouth, a shoulder, a torso, and a bottom,
The trunk portion has a constricted region including an upper constricted region and a lower constricted region connected to the upper constricted region via a small-diameter annular line,
The small-diameter annular wire has the minimum circumferential length of the body,
The upper constriction region gradually increases in circumferential direction from the small-diameter annular line upward,
The lower constriction region gradually increases in circumferential direction from the small-diameter annular line downward,
Each of the upper constriction area and the lower constriction area is composed of a large number of planar triangular panels defined by ridge lines,
When the inside of the plastic bottle is pressurized to a pressure of 1 kPa to 400 kPa, each triangular panel expands to form a convex surface protruding outward, and a curved surface is formed in the vicinity of the ridgeline between the triangular panels,
When the plastic bottle is opened, each triangular panel returns to a flat shape, and the strength of the constricted area is maintained.   Each of the upper constriction region and the lower constriction region has a structure in which a downward downward triangular panel whose bottom is upward and an upward upward triangular panel whose bottom is downward are alternately arranged in the circumferential direction. The plastic bottle according to claim 1.   The downward triangle panel and the upward triangle panel in the upper constriction area and the lower constriction area are both adjacent to each other via a ridgeline, and the downward triangle panel and the upward triangle panel both have the same shape having a pair of base angle and apex angle. The plastic bottle according to claim 2, wherein one of the pair of base angles has a base angle of 90 ° or more.   4. The plastic bottle according to claim 3, wherein in the upper constricted region and the lower constricted region, the downward triangular panel and the upward triangular panel are each composed of a non-axisymmetric triangle.   The plastic bottle according to any one of claims 1 to 4, wherein the small-diameter annular line has a regular polygonal horizontal cross section.   The plastic bottle according to any one of claims 1 to 5, wherein the bottom portion has a plurality of legs protruding downward. The ratio (d ₁ / d ₂ ) of the diameter d ₁ of the constricted region in the small-diameter annular line to the maximum diameter d ₂ of the body part is 0.60 or more and 0.95 or less. The plastic bottle according to any one of 6.   The plastic bottle according to any one of claims 1 to 7, wherein the total number of triangular panels in the constricted region is 32 or more and 96 or less.   The plastic bottle according to any one of claims 1 to 8, wherein the constriction region has a thickness of 0.07 mm to 0.40 mm.

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