JP7519024B2 - Plastic Bottles - Google Patents

Description

This disclosure relates to plastic bottles.

Recently, plastic bottles for storing liquid contents such as food and beverages have become common, and some of these plastic bottles are filled with the liquid, sealed, and then sold using vending machines.

On the other hand, in recent years, there has been a demand to reduce the amount of plastic material used in bottles and to make plastic bottles lighter. However, when making plastic bottles lighter, the thickness of the sides and bottom also becomes thinner. For this reason, for example, when a plastic bottle is inserted into a vending machine, if an impact is applied to the side of the plastic bottle, the bottom may invert and pop out (buckling). In this case, not only is the aesthetic appearance of the plastic bottle marred, but the bottom of the plastic bottle may get caught inside the vending machine, leading to clogging.

JP 2011-84315 A

A technique is also known in the past for providing radial grooves in the bottom of a plastic bottle to increase the strength of the plastic bottle against the impact of being dropped (see Patent Document 1). However, providing radial grooves in the bottom of a plastic bottle poses the problem that it becomes difficult to hold the plastic bottle by vacuum suctioning the bottom side during the process of applying a label to the plastic bottle.

The present disclosure has been made in consideration of these points, and provides a plastic bottle that prevents the bottom from inverting and popping out when an impact is applied to the side of the plastic bottle, and that can stably hold the bottom side during the process of applying a label to the plastic bottle.

The plastic bottle according to this embodiment is a plastic bottle having a mouth, a body, and a bottom, the bottom having a central portion, a peripheral portion located on the periphery of the bottom, and a flat annular ground portion located between the central portion and the peripheral portion, the central portion being provided with a plurality of first radial ribs each extending in a radial direction, the peripheral portion being provided with a plurality of second radial ribs each extending in a radial direction, the first radial ribs and the second radial ribs being disposed at a distance from each other across the ground portion.

In the plastic bottle according to this embodiment, the first radial ribs and the second radial ribs may be arranged alternately along the circumferential direction.

In the plastic bottle according to this embodiment, the central portion has a central recess and an annular inclined portion located around the central recess, and the first radial ribs may be disposed on the annular inclined portion.

In the plastic bottle according to this embodiment, the body may have a plurality of circumferential grooves and a cylindrical surface formed between the circumferential grooves.

In the plastic bottle according to this embodiment, the body may be composed only of the circumferential groove and the cylindrical surface.

In the plastic bottle according to this embodiment, the thickness of the bottom at the grounding portion may be 0.09 mm or more and 0.40 mm or less.

The plastic bottle according to this embodiment may have a weight of 6 g or more and 38 g or less.

This embodiment prevents the bottom of a plastic bottle from flipping over and popping out when an impact is applied to the side of the bottle, and also allows the bottom side to be stably held during the process of labeling the plastic bottle.

FIG. 1 is a perspective view of a plastic bottle according to an embodiment, seen from the mouth side. FIG. 2 is a front view showing a plastic bottle according to one embodiment. FIG. 3 is a plan view showing a plastic bottle according to one embodiment. FIG. 4 is a bottom view showing a plastic bottle according to one embodiment. FIG. 5 is a perspective view of a plastic bottle according to an embodiment, seen from the bottom side. FIG. 6 is a cross-sectional view of the bottom of a plastic bottle according to one embodiment (cross-sectional view taken along line VI-VI in FIG. 5). 7(a)-(d) are diagrams showing a process of attaching a heat shrink film to a plastic bottle according to one embodiment. FIG. 8 is a diagram showing a state when a load is applied from a side direction to a plastic bottle according to one embodiment. FIG. 9 is a bottom view showing a plastic bottle according to a modified example. FIG. 10 is a bottom view showing a plastic bottle according to a comparative example. FIG. 11 is a perspective view of a plastic bottle according to a comparative example, seen from the bottom side.

One embodiment will be described below with reference to the drawings. Figures 1 to 9 show one embodiment.

First, an overview of the plastic bottle according to this embodiment will be described with reference to Figures 1 to 5. In this specification, "upper" and "lower" refer to the upper and lower directions, respectively, when the plastic bottle 10 is held upright (Figures 1 and 2). In this specification, "radial direction" refers to a direction perpendicular to the central axis CL of the plastic bottle 10, and "circumferential direction" refers to the circumferential direction of a circle centered on the central axis CL of the plastic bottle 10.

The plastic bottle 10 shown in Figures 1 to 5 is produced by preparing a preform obtained by injection molding and subjecting this preform to biaxial stretch blow molding.

As shown in Figures 1 to 5, the plastic bottle 10 has a mouth 11, a neck 12 located below the mouth 11, a shoulder 13 located below the neck 12, a body 20 located below the shoulder 13, and a bottom 30 located below the body 20.

The mouth portion 11 has a threaded portion 14 that is screwed onto a cap 18 (see Figures 7 and 8), and a flange portion 17 located below the threaded portion 14. The plastic bottle 10 is filled with contents such as liquid, and the cap 18 is screwed onto the mouth portion 11 to obtain a container containing the contents.

The neck 12 is located between the flange 17 and the shoulder 13, and has a generally cylindrical shape with a generally uniform diameter. The shoulder 13 is located between the neck 12 and the body 20, and has a shape whose diameter gradually increases from the neck 12 side toward the body 20 side.

The body 20 has a generally cylindrical shape overall, and multiple circumferential grooves 22-24 are formed on its surface. The multiple circumferential grooves 22-24 are composed of circumferential grooves of different depths. Specifically, the circumferential grooves 22-24 include a first circumferential groove 22 with the maximum depth, a second circumferential groove 23 with an intermediate depth, and a third circumferential groove 24 with the minimum depth. Each of these circumferential grooves 22-24 extends around the entire circumference of the body 20, and their vertical widths are uniform throughout the entire circumference.

In this case, the body 20 is formed with the third circumferential groove 24, the third circumferential groove 24, the third circumferential groove 24, the second circumferential groove 23, the first circumferential groove 22, the second circumferential groove 23, the first circumferential groove 22, the third circumferential groove 24, the third circumferential groove 24, and the second circumferential groove 23 in this order from the shoulder 13 side to the bottom 30 side. However, the arrangement of the circumferential grooves 22 to 24 is not limited to this, and the first circumferential groove 22, the second circumferential groove 23, and the third circumferential groove 24 can be arranged in any order from the shoulder 13 side of the body 20 to the bottom 30 side.

Of the circumferential grooves 22 to 24 formed in the body 20, the two first circumferential grooves 22 mainly function to absorb reduced pressure by contracting vertically when the pressure inside the plastic bottle 10 is reduced. The two first circumferential grooves 22 also serve to increase the strength of the area around the center of the body 20, which is a part that is easily deformed.

The two second circumferential grooves 23 located near the vertical center of the body 20 mainly serve to increase the strength of the area around the center of the body 20, which is a part that is easily deformed. In addition, these two second circumferential grooves 23 also perform an auxiliary function of absorbing reduced pressure by contracting in the vertical direction.

The five third circumferential grooves 24 mainly serve to increase the strength of the areas above and below the vertical center, preventing this area from being dented in the radial direction. The five third circumferential grooves 24 also have an auxiliary function of absorbing reduced pressure by contracting in the vertical direction. Note that the depth of the third circumferential grooves 24 is not too large (for example, about the same as the first circumferential groove 22 or the second circumferential groove 23), which prevents the volume of the plastic bottle 10 from decreasing too much.

The single second circumferential groove 23 provided near the bottom 30 serves primarily to increase the strength of the peripheral area of the bottom 30, which is a portion of the body 20 that is relatively susceptible to deformation.

On the other hand, the areas of the body 20 where the circumferential grooves 22 to 24 are not formed are made up of a cylindrical surface 25. In other words, the cylindrical surfaces 25 are formed between the circumferential grooves 22 to 24. In this case, the body 20 is made up only of the circumferential grooves 22 to 24 and the cylindrical surface 25.

The area (cylindrical surface 25) where the circumferential grooves 22-24 are not formed has a uniform diameter from just below the shoulder 13 to just above the bottom 30. This allows a wide area of contact with adjacent plastic bottles 10 when the plastic bottle 10 is stored sideways inside the vending machine, preventing deformation of the body 20 inside the vending machine.

Next, the bottom portion 30 will be described with reference to Figures 4 to 6.

The bottom 30 has a central portion 31 located at the center of the bottom 30, a peripheral portion 33 located at the periphery of the bottom 30, and a flat annular grounding portion 32 located between the central portion 31 and the peripheral portion 33. The central portion 31 is provided with a plurality of first radial ribs 41 each extending in the radial direction. The peripheral portion 33 is provided with a plurality of second radial ribs 42 each extending in the radial direction.

The central portion 31 has a central recess 34 and an annular inclined portion 35 located around the central recess 34.

The central recess 34 is recessed upward (inward of the plastic bottle 10). The central recess 34 has an approximately truncated cone shape overall, and has a recess top surface 36 and a recess inclined surface 37 located around the recess top surface 36.

The recessed top surface 36 is a flat curved surface without any irregularities, and is slightly higher radially inward than radially outward (see FIG. 6). The recessed top surface 36 has a circular shape when viewed from the bottom, but is not limited to this and may be polygonal. The diameter D2 of the recessed top surface 36 may be 15% to 50% of the maximum diameter D1 of the body 20, and preferably 20% to 30% (see FIG. 4 and FIG. 6). The distance H1 between the center of the recessed top surface 36 (a point passing through the central axis CL) and the ground surface S may be 5% to 25% of the maximum diameter D1 of the body 20, and preferably 10% to 15% (see FIG. 6).

The recess inclined surface 37 has the shape of a side surface of a truncated cone that constitutes the central recess 34. This recess inclined surface 37 is inclined with respect to the ground surface S. In a vertical cross section (cross section passing through the central axis CL) of the bottom 30, the angle θ1 between the recess inclined surface 37 and the ground surface S may be 40° or more and 80° or less (see FIG. 6). The radial inner end of the first radial rib 41 described later is connected to the recess inclined surface 37.

The annular inclined portion 35 is located radially outside the central recess 34 and radially inside the grounding portion 32. The upper end of the annular inclined portion 35 is connected to the lower end of the recess inclined surface 37, and the lower end of the annular inclined portion 35 is connected to the radially inner end of the grounding portion 32. The annular inclined portion 35 has a shape of a side surface of a truncated cone as a whole. The annular inclined portion 35 is composed of a flat curved surface without any grooves or the like formed other than the first radial rib 41. The annular inclined portion 35 is inclined with respect to the grounding surface S. In a vertical cross section (cross section passing through the central axis CL) of the bottom 30, the angle θ2 between the annular inclined portion 35 and the grounding surface S may be 10° or more and 30° or less (see FIG. 6). Note that this angle θ2 is smaller than the angle θ1 between the recess inclined surface 37 and the grounding surface S described above.

A plurality of first radial ribs 41 are radially provided on the annular inclined portion 35. Specifically, eight first radial ribs 41 are arranged at equal intervals (equally spaced at 45° intervals) in the circumferential direction. The number of first radial ribs 41 may be four or more and twelve or less. Each first radial rib 41 extends radially when viewed from the bottom surface direction. Each first radial rib 41 has a radial inner end connected to the annular inclined portion 35 and a radial outer end terminated at the inner end of the grounding portion 32. That is, each first radial rib 41 is connected to the central recess 34. Each first radial rib 41 is formed in a groove shape and has an approximately U-shaped or approximately C-shaped cross section perpendicular to the width direction. Each first radial rib 41 is arranged along the inclination of the annular inclined portion 35. That is, in a vertical cross section of the bottom 30 (a cross section passing through the central axis CL), each of the first radial ribs 41 is inclined at the same angle as the annular inclined portion 35 with respect to the ground surface S (see FIG. 6).

The length L1 of each first radial rib 41 when viewed from the bottom may be 15% to 50% of the maximum diameter D1 of the body 20, and preferably 20% to 30% (see FIG. 4). The width W1 of each first radial rib 41 when viewed from the bottom may be 1% to 15% of the maximum diameter D1 of the body 20, and preferably 2% to 10% (see FIG. 4). The depth d1 of each first radial rib 41 may be 1% to 15% of the maximum diameter D1 of the body 20, and preferably 2% to 10% (see FIG. 6). The depth d1 of the first radial rib 41 refers to the distance measured in a direction perpendicular to the surface of the annular inclined portion 35.

The grounding portion 32 is located radially outside the annular inclined portion 35 and radially inside the peripheral portion 33. The radial inner end of the grounding portion 32 is connected to the lower end of the annular inclined portion 35, and the radial outer end of the grounding portion 32 is connected to the lower end of the peripheral portion 33. This grounding portion 32 is the portion that contacts the ground surface S when the plastic bottle 10 is upright (see FIG. 6). When viewed from the bottom surface direction, the grounding portion 32 has a circular ring shape with no interruptions in the circumferential direction (see FIGS. 4 and 5). The grounding portion 32 is also disposed between the first radial rib 41 and the second radial rib 42. In this case, the grounding portion 32 is connected to the first radial rib 41 and the second radial rib 42, respectively. The grounding portion 32 separates the first radial rib 41 and the second radial rib 42 from each other in the radial direction and the circumferential direction. The grounding portion 32 is made of a flat plane without any unevenness or grooves. The width W2 (radial distance) of the grounding portion 32 may be 1% to 15% of the maximum diameter D1 of the body portion 20, and preferably 2% to 8% (see FIG. 4). The inner circumference of the grounding portion 32 (the outer circumference of the annular inclined portion 35) is circular when viewed from the bottom surface direction, but is not limited to this and may be polygonal, for example. For example, the inner circumference of the grounding portion 32 may be octagonal in shape corresponding to the number of the first radial ribs 41. In this case, the area of the grounding portion 32 can be increased, and the stability of the plastic bottle 10 can be improved when the grounding portion 32 is grounded.

The peripheral portion 33 is located radially outside the grounding portion 32. The radial inner end of the peripheral portion 33 is connected to the radial outer side of the grounding portion 32, and the radial outer end of the peripheral portion 33 is connected to the lower end of the body portion 20. The peripheral portion 33 has a circular ring shape when viewed from the bottom surface direction. The peripheral portion 33 rises from the lower side (the grounding portion 32 side) to the upper side (the body portion 20 side) as it moves from the radial inner side to the radial outer side. In addition, in a vertical cross section (cross section passing through the central axis CL) of the bottom portion 30, the peripheral portion 33 is curved so that the angle with respect to the grounding surface S gradually increases as it moves from the radial inner side to the radial outer side (see FIG. 6). The peripheral portion 33 is composed of a flat curved surface without any grooves or the like formed therein, except for the second radial rib 42.

A plurality of second radial ribs 42 are provided radially on the peripheral portion 33. Specifically, eight second radial ribs 42 are arranged at equal intervals (at 45° intervals) in the circumferential direction. The number of second radial ribs 42 is the same as the number of first radial ribs 41, and may be 4 to 12. Each second radial rib 42 extends radially when viewed from the bottom surface direction, and its radial inner end is connected to the grounding portion 32, while its radial outer end terminates within the peripheral portion 33. Each second radial rib 42 is formed in a groove shape and has an approximately U-shaped or approximately C-shaped cross section perpendicular to the width direction. Each second radial rib 42 is arranged along the inclination of the peripheral portion 33. That is, each second radial rib 42 is curved so that the angle with respect to the grounding surface S gradually increases from the radial inner side to the radial outer side in the vertical cross section (cross section passing through the central axis CL) of the bottom portion 30.

The length L2 of each second radial rib 42 when viewed from the bottom may be 5% to 20% of the maximum diameter D1 of the body 20, and preferably 6% to 12% (see FIG. 6). The length H2 of each second radial rib 42 in the direction parallel to the central axis CL may be 5% to 20% of the maximum diameter D1 of the body 20, and preferably 8% to 15% (see FIG. 6). In addition, the width W3 of each second radial rib 42 when viewed from the bottom may be 1% to 15% of the maximum diameter D1 of the body 20, and preferably 2% to 10% (see FIG. 4). Furthermore, the depth d2 of each second radial rib 42 may be 1% to 15% of the maximum diameter D1 of the body 20, and preferably 2% to 10% (see FIG. 6). The depth d2 of the second radial rib 42 refers to the distance measured in a direction perpendicular to the surface of the peripheral edge 33.

As described above, each first radial rib 41 and each second radial rib 42 are arranged radially spaced apart from each other across the ground contact portion 32. The first radial ribs 41 and the second radial ribs 42 are also spaced apart in the circumferential direction and are arranged alternately along the circumferential direction. Therefore, when viewed from the bottom surface, the angle θ3 between the center line along the longitudinal direction of the first radial rib 41 and the center line along the longitudinal direction of the adjacent second radial rib 42 is 22.5° (see FIG. 4).

However, the size of such a plastic bottle 10 is not limited, and the bottle may be of any size. For example, the plastic bottle 10 may be a lightweight bottle with a full capacity of 200 ml to 2000 ml, more preferably 450 ml to 650 ml.

The thickness of the grounding portion 32 of the bottom 30 is not limited to this, but can be, for example, 0.09 mm or more and 0.40 mm or less. By making the grounding portion 32 0.40 mm or less in thickness, the weight of the plastic bottle 10 can be reduced. On the other hand, by making the grounding portion 32 0.09 mm or more in thickness, the bottom 30 can be prevented from popping out and becoming permanently deformed when the plastic bottle 10 is placed in a vending machine or dropped.

Furthermore, the weight of the plastic bottle 10 can be set to 6 g or more and 38 g or less for a plastic bottle 10 with a capacity of 2000 ml or less, although this is not limited thereto. In this way, the weight of the plastic bottle 10 can be reduced.

The plastic bottle 10 can also be produced by biaxially stretching and blow molding a preform made by injection molding a synthetic resin material. The main material for the preform, i.e., the plastic bottle 10, can be a thermoplastic resin, in particular PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PLA (polylactic acid), etc. The material for the plastic bottle 10 can also be recycled plastic made by sorting, crushing, and cleaning used plastic products.

The shape of the body 20 is not limited to the bellows structure shown in Figures 1 and 2. For example, the body 20 may be a flat cylindrical surface as a whole, like a carbonated beverage bottle. The body 20 may also have a pressure absorbing structure (e.g., a pressure absorbing panel). The shape of the body 20 is not necessarily limited to a cylindrical shape, and may be a polygonal tube shape such as a square.

Next, we will explain the operation of this embodiment with such a configuration.

First, an empty plastic bottle 10 is prepared, and the contents, such as liquid, are filled into the plastic bottle 10. Next, the mouth 11 is closed with a cap 18 (see Figures 7 and 8).

A heat-shrinkable film 45 is attached to the plastic bottle 10 (container containing the contents) that has been closed in this manner.

In this case, first, as shown in FIG. 7(a), the plastic bottle 10 is placed on the suction plate 51. The suction plate 51 has suction holes 52 at positions corresponding to the plastic bottle 10, and the plastic bottle 10 is held on the suction plate 51 by vacuum suction through the suction holes 52. At this time, the grounding portion 32 of the bottom 30 is in close contact with the upper surface of the suction plate 51. During this time, the suction plate 51 rotates (spins on its axis), and the plastic bottle 10 suctioned and held on the suction plate 51 also rotates (revolves) together with the suction plate 51. The plastic bottle 10 is held on the suction plate 51 until the attachment of the heat-shrinkable film 45 is complete.

At this time, a sealed space V is formed between the suction plate 51 and the bottom 30 of the plastic bottle 10 by the central portion 31. That is, as described above, the first radial rib 41 and the second radial rib 42 of the bottom 30 are arranged at a distance from each other with the grounding portion 32 in between. In addition, the grounding portion 32 is formed in an annular shape without interruption around the entire circumference. Therefore, the first radial rib 41 and the second radial rib 42 do not communicate with each other, and the sealed space V does not communicate with the outside. This allows the plastic bottle 10 to be firmly suctioned to the suction plate 51.

If the first radial rib 41 and the second radial rib 42 of the bottom 30 were to communicate with each other, external air would enter the sealed space V through the first radial rib 41 and the second radial rib 42. In this case, the suction plate 51 would not be able to strongly suction the plastic bottle 10, and there is a risk that the centrifugal force of the suction plate 51 would cause the plastic bottle 10 to fall.

Next, as shown in FIG. 7(b), an unshrunk, cylindrical heat-shrinkable film 45 is prepared. This heat-shrinkable film 45 may be produced, for example, by forming a sheet of film into a cylindrical shape slightly larger than the diameter of the plastic bottle 10 and bonding the ends together.

Next, as shown in FIG. 7(c), the cylindrical heat-shrinkable film 45 is lowered from above and positioned so as to cover a predetermined position around the plastic bottle 10.

Next, as shown in FIG. 7(d), the unshrunk heat-shrinkable film 45 is heated to a temperature of, for example, 100° C. or more and 200° C. or less by a heating device 53 such as a heater. This causes the heat-shrinkable film 45 to heat-shrink to conform to the shape of the plastic bottle 10 and adhere to the surface of the plastic bottle 10.

In this way, the heat-shrinkable film 45 is attached around the plastic bottle 10. This heat-shrinkable film 45 is provided around the entire circumference of the plastic bottle 10, and has a substantially circular horizontal cross section.

The heat-shrinkable film 45 may be adhered to the plastic bottle 10. The heat-shrinkable film 45 may also be a label on which a pattern or letters are printed. Materials that are generally used for shrink films can be used as materials for the heat-shrinkable film.

The plastic bottle 10 is then inserted, for example, into a vending machine and sold. In the vending machine, a load F1 may be applied laterally (perpendicular to the central axis CL) to the body 20 due to, for example, the impact caused when the plastic bottle 10 is inserted (see FIG. 8). When the load F1 is applied laterally to the body 20 in this way, the internal pressure of the plastic bottle 10 increases, and as a result, a force F2 is applied from the inside to the outside to the bottom 30. Note that the heat-shrinkable film 45 is not shown in FIG. 8.

In contrast, according to the present embodiment, the center 31 of the bottom 30 is provided with a number of first radial ribs 41 each extending in the radial direction. This increases the strength of the center 31 of the bottom 30, and suppresses the phenomenon (buckling) in which the bottom 30 inverts and pops outward when an impact is applied to the body 20 of the plastic bottle 10 from the side. As a result, the overall length of the plastic bottle 10 is extended, preventing the plastic bottle 10 from clogging the vending machine, and making it easier to sell the plastic bottle 10 in the vending machine. In contrast, if the center 31 of the bottom 30 does not have the first radial ribs 41, there is a risk that the bottom 30 will invert and pop out when an impact is applied to the body 20 from the side (see the imaginary line in FIG. 8).

In addition, according to this embodiment, the peripheral portion 33 of the bottom portion 30 is provided with a plurality of second radial ribs 42 each extending in a radial direction, thereby increasing the strength of the peripheral portion 33. As a result, when a force F2 is applied to the body portion 20 from the side due to an impact, for example, when a plastic bottle 10 is inserted into a vending machine, the peripheral portion 33 of the bottom portion 30 is prevented from being dented, and the appearance of the bottom portion 30 can be maintained in a good condition.

The effect of suppressing the inversion and deformation of the bottom 30 described above can be particularly pronounced when the plastic bottle 10 is made lighter and the bottom 30 is made thinner. Specifically, when the plastic bottle 10 weighs 6 g or more and 38 g or less and the thickness of the bottom 30 at the contact portion 32 is 0.09 mm or more and 0.40 mm or less, the inversion and deformation of the bottom 30 can be suppressed more effectively.

In this way, this embodiment can prevent the bottom 30 from inverting and popping out when an impact is applied to the body 20 of the plastic bottle 10 from the side, and can stably hold the bottom 30 side in place during the process of applying the heat-shrinkable film 45 to the plastic bottle 10.

In addition, according to this embodiment, the multiple first radial ribs 41 and the multiple second radial ribs 42 are arranged alternately along the circumferential direction. This allows a sufficient distance between each first radial rib 41 and each second radial rib 42, so that when attaching the heat-shrinkable film 45 around the plastic bottle 10 as described above, the plastic bottle 10 can be more reliably adsorbed by the suction plate 51. However, this is not limited to this, and the multiple first radial ribs 41 and the multiple second radial ribs 42 may be arranged on the same straight line when viewed from the bottom surface direction (see FIG. 9).

In addition, according to this embodiment, the central portion 31 of the bottom portion 30 has a central recess 34 and an annular inclined portion 35 located around the central recess 34, and the multiple first radial ribs 41 are arranged on the annular inclined portion 35. As a result, the annular inclined portion 35 is reinforced by the multiple first radial ribs 41, so that when an impact is applied to the body portion 20 from the side, the central recess 34 can be prevented from inverting and popping out together with the annular inclined portion 35.

In addition, according to this embodiment, the body 20 has multiple circumferential grooves 22-24 and a cylindrical surface 25 formed between the circumferential grooves 22-24, so that it can absorb reduced pressure inside the plastic bottle 10.

That is, in a closed plastic bottle 10 (container containing contents), the specific gravity of the contents may change, or the contents may absorb oxygen present in the empty space (head space) of the plastic bottle 10, resulting in a reduced pressure inside the bottle. When negative pressure is generated inside the plastic bottle 10, stress is generated toward the inside of the plastic bottle 10. In contrast, in this embodiment, multiple circumferential grooves 22-24 are formed in the body 20. When the inside of the plastic bottle 10 is reduced in pressure, these circumferential grooves 22-24 are deformed in the vertical direction (direction parallel to the central axis CL), so that the plastic bottle 10 is reduced in the height direction. As a result, the volume of the plastic bottle 10 as a whole is reduced, and the reduced pressure of the bottle can be absorbed. On the other hand, the plastic bottle 10 does not undergo any significant deformation in appearance. Specifically, when the contents are filled into a sealed plastic bottle 10 and 2% of the filled contents are removed from the plastic bottle 10, it is preferable that the height of the body 20 is reduced by 1% or more.

In addition, according to this embodiment, the plastic bottle 10 filled with the liquid content may be stored in a vending machine in a horizontal position. In this case, since the body 20 is reinforced by the circumferential grooves 22-24, deformation of the body 20 inside the vending machine can be suppressed.

In addition, according to this embodiment, since the body 20 is composed only of the circumferential grooves 22-24 and the cylindrical surface 25, it is not necessarily necessary to provide a vacuum absorption panel on the body 20. Therefore, it is possible to prevent the volume of the plastic bottle 10 from being significantly reduced by the vacuum absorption panel.

The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[Example 1]
A plastic bottle having the shape shown in Fig. 5 was used. The content volume of the plastic bottle was 550 mL, and the weight per unit area (mass of the plastic bottle) was 15 g.

[Comparative Example 1]
A plastic bottle 50 (see FIG. 11) similar to that of Example 1 was used, except that it had a bottom 51 as shown in FIG.

<<Side impact resistance test>>
The plastic bottles of Example 1 and Comparative Example 1 were filled with 530 mL of water, capped, and then dropped from a height of 1.5 m. Each plastic bottle was dropped 10 times with the side of the bottle facing downward, and the side impact resistance was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.

(Evaluation criteria)
OK: Of the 20 plastic bottles, the phenomenon of the bottom inverting and popping out did not occur.
NG: The bottom of one or more of the 20 plastic bottles inverted and popped out.

As is clear from the table above, the plastic bottle of Example 1 has higher resistance to side impacts than the plastic bottle of Comparative Example 1.

The present disclosure is not limited to the above-described embodiment as it is, and in the implementation stage, the components can be modified and embodied without departing from the gist of the disclosure. In addition, various inventions can be formed by appropriate combinations of the multiple components disclosed in the above-described embodiment. Some components may be deleted from all the components shown in the embodiment.

REFERENCE SIGNS LIST 10 Plastic bottle 11 Mouth 12 Neck 13 Shoulder 14 Threaded portion 17 Flange 20 Body 22 First circumferential groove 23 Second circumferential groove 24 Third circumferential groove 25 Cylindrical surface 30 Bottom 31 Central portion 32 Ground contact portion 33 Peripheral edge 34 Central recess 35 Annular inclined portion 36 Recess top surface 37 Recess inclined surface 41 First radial rib 42 Second radial rib 50 Plastic bottle 51 Bottom

Claims (6)

A plastic bottle having a mouth, a body, and a bottom,
The bottom portion has a central portion, a peripheral portion located on the periphery of the bottom portion, and a flat annular ground contact portion located between the central portion and the peripheral portion,
a plurality of first radial ribs each extending radially in the central portion;
a plurality of second radial ribs are provided on the peripheral edge, each of the second radial ribs extending in a radial direction;
The first radial rib and the second radial rib are spaced apart from each other across the ground contact portion,
The second radial ribs are equally spaced apart in the circumferential direction,
The first radial rib and the second radial rib are each formed in a groove shape when viewed from a bottom surface direction,
A plastic bottle , wherein the plurality of first radial ribs and the plurality of second radial ribs are arranged alternately around the entire circumference along a circumferential direction. 2. The plastic bottle of claim 1 , wherein the central portion has a central recess and an annular ramp portion located around the central recess, and the first plurality of radial ribs are disposed on the annular ramp portion. 3. The plastic bottle according to claim 1, wherein the body portion has a plurality of circumferential grooves and a cylindrical surface formed between the circumferential grooves. 4. The plastic bottle according to claim 3 , wherein the body portion is composed only of the circumferential groove and the cylindrical surface. 5. The plastic bottle according to claim 1 , wherein the thickness of the bottom at the ground contact portion is 0.09 mm or more and 0.40 mm or less. 6. The plastic bottle according to claim 1 , having a weight of 6 g or more and 38 g or less.