JP2011037463A - Plastic bottle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic bottle which suppresses the deformation of a trunk when the inside of the bottle is put in a positive pressure state, is easy to be carried, and has a superior design property. <P>SOLUTION: The plastic bottle 10 includes a mouth 11, a shoulder 12, the trunk 20, and a bottom 30. The trunk 20 has a constricted area 23 including an upper constricted area 24 and a lower constricted area 26 connected to the upper constricted area 24 via a small-diameter annual line 25. The upper constricted area 24 and the lower constricted area 26 are composed of a number of flat triangular panels 24a and 24b and of flat triangular panels 26a and 26b, respectively. This suppresses the deformation of the trunk 20 when the inside of the plastic bottle 10 is put in a positive pressure state. <P>COPYRIGHT: (C)2011,JPO&INPIT

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.

  Thus, a plastic bottle (positive pressure bottle) having a positive pressure inside needs to have a body shape and a bottom shape imparted with pressure resistance. Therefore, the body shape and bottom shape of the positive pressure bottle are subject to some restrictions. For example, when a positive pressure is applied to the inside of the positive pressure bottle, the body of the bottle expands, and there is a restriction that it is difficult to give a special shape such as a panel to the body.

  At the same time, when producing (designing) positive pressure bottles, design is also required to increase the willingness to purchase products. Therefore, it is necessary to provide a plastic bottle that can maintain the design and dimensions of the body even during positive pressure.

JP 7-125737 A JP 2007-62800 A

  The present invention has been made in consideration of such points, and even when the inside is a positive pressure, the deformation of the body can be reduced, and a plastic bottle that is easy to hold and excellent in design is provided. The purpose is to provide.

  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. And the small-diameter annular line has a minimum circumferential length of the body portion, and the upper constriction area gradually increases in the circumferential direction upward from the small-diameter annular line, and the lower constriction The region gradually increases in the circumferential direction downward from the small-diameter annular line, and the upper constriction region and the lower constriction region are both composed of a large number of planar triangular panels, and the upper constriction region and the lower constriction region are Both have a structure in which downward downward triangular panels with bottoms facing upward and upward upward triangular panels with bottoms downward are arranged alternately in the circumferential direction. The downward triangular panel and the upward triangular panel in the region are both adjacent to each other via a ridgeline, and the downward triangular panel and the upward triangular panel both have the same shape having a pair of base angles and apex angles, Any one of the corners has a base angle of 90 ° or more, and the downward triangular panel and the upward triangular panel both have a valley-shaped ridge line that protrudes inward and a mountain-shaped ridge line that protrudes outward, except for the bottom side. It is a plastic bottle characterized by having.

  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 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, the trunk portion has a constriction region including an upper constriction region and a lower constriction region connected to the upper constriction region via a small-diameter annular line, and the upper constriction region and the lower constriction region are Also consists of a number of planar triangular panels. Thereby, even when the inside is set to a positive pressure, the deformation of the body portion can be reduced and the plastic bottle can be easily held. In addition, the design of the plastic bottle can be maintained.

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 the triangular panels exceeds 96, it is not preferable because defective shaping occurs when the plastic bottle 10 is produced by blow molding.

  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 or depressurized, a force is applied to the surfaces of the triangular panels 24a, 24b, 26a, and 26b, so that the direction of the force may be uniform in the circumferential direction. it can. Thereby, the constriction area | region 23 can be made difficult to deform | transform.

  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. When the horizontal cross section of the small-diameter annular line 25 is a hexagon or less, when the inside of the bottle is pressurized or depressurized, the constriction region 23 is greatly bulged, and the constriction region 23 is less likely to be reversibly deformed. On the other hand, when the horizontal cross section of the small-diameter annular line 25 is 25 squares or more, shaping failure occurs.

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, if 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 the aspect of universal design suitability (UD suitability) 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 0.30. When this ratio (h ₁ / h ₂ ) is less than 0.20 (0.20> h ₁ / h ₂ ), the plastic bottle 10 becomes difficult to hold, and therefore the universal design suitability (UD suitability) Is not preferable. On the other hand, when this ratio (h ₁ / h ₂ ) exceeds 0.60 (h ₁ / h ₂ > 0.60), a lightweight bottle causes poor shaping at the tip of the foot.

  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. Accordingly, the two hypotenuses (mountain ridge line 24d, valley ridge line 24c) constituting each downward triangle panel 24a are inclined in the same direction with respect to the central axis Z of the bottle as viewed from the front. Also, the two oblique sides (mountain ridge line 24d, valley ridge line 24c) are inclined inward of the plastic bottle 10 with respect to the horizontal plane.

  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.

  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 + cobalt 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.

  By the way, in the present embodiment, the body portion 20 has a constricted region 23 including an upper constricted region 24 and a lower constricted region 26, and each of the upper constricted region 24 and the lower constricted region 26 has a large number of planar triangles. It consists of panels 24a, 24b, 26a, 26b. As a result, the plastic bottle 10 is formed into a thin wall and the inside thereof is set to a positive pressure, and even when a force is applied from the inside of the body 20 to the outside, a designable body shape can be obtained. Can be maintained. In addition, the ease of holding the plastic bottle 10 (UD suitability) can be maintained.

  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 (designability, UD suitability) 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 constricted region 23 is unlikely to expand in the height direction, so that the overall height change of the plastic bottle 10 can be suppressed to a small level.

  Further, according to the present embodiment, since the small-diameter annular line 25 has a regular polygonal horizontal cross section, the direction of the force applied to the constricted region 23 is made uniform in the circumferential direction when the inside of the bottle is pressurized or depressurized. It is possible to make the constricted region 23 difficult to deform.

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

(Evaluation of UD suitability)
First, the following five types of plastic bottles (Example 1, Modified Example 1, Modified Example 2, Comparative Example 1, and Comparative Example 2) are easy to hold when the inside of the bottle is set to a positive pressure (UD suitability). ) Was evaluated.

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.

(Modification 1)
Except that the diameter d ₁ of the constricted region 23 is reduced to 40 mm, the same procedure as in Example 1 is carried out to produce a 500 ml plastic bottle 10 (Modification 1) having the same weight and thickness as in Example 1. However, blow molding could not be performed due to poor shaping.

(Modification 2)
To the diameter d ₁ of the constricted region 23 and thick as 65 mm, except, in the same manner as in Example 1 to prepare a plastic bottle 10 (Modification 2) for 500ml with the same weight and thickness as in Example 1 . In Modification 2, the ratio (d ₁ / d ₂ ) of the diameter d ₁ (65 mm) of the constricted region 23 to the maximum diameter d ₂ (68 mm) of the body portion 20 was 0.96.

(Comparative Example 1)
A 500 ml plastic bottle (Comparative Example 1) having a constricted region 23 and 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 500 ml plastic bottle (Comparative Example 2) having no constricted region 23 and 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.

  Next, an inert gas is injected into four types of plastic bottles (Example 1, Modified Example 2, Comparative Example 1, and Comparative Example 2) excluding Modified Example 1 among these, and the internal pressure thereof is positive ( 50 kPa).

  Next, an evaluation of ease of holding (five-step evaluation) was performed on 20 panelists to evaluate UD suitability. As a result, as is clear from the item of “Average score” in Table 1, it was found that the plastic bottle 10 of Example 1 was most excellent in terms of UD suitability. In addition, the blow moldability and formability of these five types of plastic bottles were also evaluated (see Table 1).

(Total number of triangle panels)
Subsequently, for three types of plastic bottles (Example 1, Modified Example 3, and Modified Example 4), the blow moldability and the formability when the total number of triangular panels was changed were evaluated.

(Modification 3)
An attempt was made to produce a 500 ml plastic bottle (Modification 3) in which the total number of triangular panels provided in the constricted region 23 was 20, but blow molding could not be performed due to poor shaping.

(Modification 4)
A 500 ml plastic bottle (Modification 4) in which the total number of triangular panels provided in the constricted region 23 was 100 was produced. This plastic bottle (Modification 4) has the same weight as the plastic bottle 10 of Example 1.

  Next, an inert gas was injected into the plastic bottle 10 of Example 1 and the plastic bottle of Modification 4 described above, and each was sealed with a positive pressure (50 kPa).

  Next, a blow molding test was performed on these three types (Example 1, Modification 3 and Modification 4) of plastic bottles. As a result, as described above, the plastic bottle of Modification 3 tended to deteriorate the blow molding suitability (see Table 1). On the other hand, with regard to the plastic bottle of Modification 4, the UD suitability was lowered due to a decrease in handling suitability (side wall strength).

DESCRIPTION OF SYMBOLS 10 Plastic bottle 11 Mouth part 12 Shoulder part 13 Annular step part 20 Trunk part 21 Upper cylindrical part 21a Reinforcing groove 22 Lower cylindrical part 23 Constriction area 24 Upper constriction area 24a, 26a Downward triangular panel 24b, 26b Upward triangular panel 24c, 26c Valley Ridge line 24d, 26d mountain ridge line 25 small-diameter annular line 26 lower constriction region 27 upper annular line 28 lower annular line 30 bottom

Claims (6)

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,
The upper constriction area and the lower constriction area both consist of a number of planar triangular panels,
Each of the upper constriction region and the lower constriction region has a structure in which a downward downward triangular panel with the bottom extending upward and an upward upward triangular panel with the bottom downward are alternately arranged in the circumferential direction.
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 base angle of one of the pair of base angles is 90 ° or more,
Each of the downward triangular panel and the upward triangular panel has a valley-shaped ridge line that protrudes inward and a mountain-shaped ridge line that protrudes outward in the sides other than the bottom.   2. The plastic bottle according to claim 1, 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.   3. The plastic bottle according to claim 1, wherein the small-diameter annular line has a regular polygonal horizontal cross section. 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. 4. The plastic bottle according to any one of 3.   The plastic bottle according to any one of claims 1 to 4, 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 5, wherein the constricted region has a thickness of 0.07 mm to 0.40 mm.

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