JP2024119781A - Plastic bottles and filled products - Google Patents

Abstract

[Problem] To realize a plastic bottle that is both pressure-resistant and moldable, and a filled product that uses said plastic bottle. [Solution] A plastic bottle formed into a bottomed cylindrical shape on the bottom surface 2 side, comprising a protruding part 21 provided in the center of the bottom surface 2, a grounding part 22 that surrounds the protruding part 21, a connecting part 23 that connects the protruding part 21 and the grounding part 22, and a plurality of groove parts 24 that extend between the protruding part 21 and the outer periphery of the bottom surface 2, the connecting part 23 being a curved surface that protrudes outward from the plastic bottle, and the height H2 of the end 24a of the groove part 24 on the outer periphery side of the bottom surface 2, taken from the grounding part 22 as the reference, is higher than the height H1 of the protruding part 21, taken from the grounding part 22 as the reference. [Selected Figure] Figure 2

Description

Application for exception to loss of novelty has been filed

The present invention relates to a plastic bottle and a filled product in which the plastic bottle is filled with contents.

Plastic bottles are widely used as containers for distributing, selling, and storing beverages and other liquid products. These liquid products are filled into plastic bottles and distributed in a sealed state. Because the container is sealed, if the internal pressure increases due to a change in the state of the liquid product, stress is applied to the plastic bottle from the inside. Therefore, plastic bottles that can withstand such stress have been proposed.

For example, Japanese Patent Application Laid-Open No. 2007-8506 (Patent Document 1) discloses a resin bottle in which a specific shape is provided at the bottom, making it less likely to undergo inverted deformation (so-called buckling) at the bottom even under heating conditions of 120 to 130°C during retort processing. In addition, Japanese Patent Application Laid-Open No. 2009-208813 (Patent Document 2) discloses a plastic bottle having a raised bottom portion with reinforcing ribs provided at the raised bottom portion. In the plastic bottle of Patent Document 2, the shape of the raised bottom portion is reliably maintained during normal pressure increases and when beverages are filled at high temperatures, and during unexpected pressure increases due to secondary fermentation, etc., the raised bottom portion inverts to absorb the pressure.

JP 2007-8506 A JP 2009-208813 A

As in Patent Documents 1 and 2, pressure-resistant structures that can withstand rising internal pressure have been studied in the past, but there was room for improvement in terms of balancing the pressure-resistant structure with the formability of the container. In particular, in both Patent Documents 1 and 2, a dome-shaped pressure-resistant structure is provided on the bottom surface of the container, but such a dome structure can be difficult to mold into a thin wall. This is for the reasons explained below.

In the process of stretch-blow molding a plastic bottle, the resin material is first stretched by the rod and comes into contact with the part of the mold that corresponds to the dome structure from above. When the resin material comes into contact with the mold, its temperature drops and its fluidity decreases. The resin material then flows horizontally along the dome structure in a state of reduced fluidity. That is, in the molding of a conventional plastic bottle with a dome structure, the flow direction of the resin material changes from a downward flow (due to the rod stretching) to a horizontal flow (due to following the dome structure) in a state where the fluidity of the resin material is reduced, so molding is forced to be carried out under unfavorable conditions in terms of fluidity. Therefore, in conventional plastic bottles, it is easy for the resin material to not be distributed evenly at the bottom, which can cause problems such as bursting.

Therefore, there is a need to develop a plastic bottle that is both pressure resistant and moldable, and to develop filled products that use such plastic bottles.

The plastic bottle according to the present invention is a plastic bottle whose bottom side is formed into a bottomed cylinder, and includes a protruding portion provided in the center of the bottom side, a grounding portion surrounding the protruding portion, a connection portion connecting the protruding portion and the grounding portion, and a plurality of groove portions extending between the protruding portion and the outer periphery of the bottom side, and is characterized in that the connection portion is a curved surface that protrudes outward from the plastic bottle, and the height of the end of the groove portion on the outer periphery side of the bottom side relative to the grounding portion is higher than the height of the protruding portion relative to the grounding portion.

This configuration allows the plastic bottle to have both pressure resistance and moldability. Therefore, for example, it is possible to prevent buckling while reducing the wall thickness of the plastic bottle compared to conventional methods, thereby contributing to resource conservation.

The filled product according to the present invention is a plastic bottle with a bottom side formed into a bottomed cylinder, comprising a protruding part provided in the center of the bottom side, a grounding part surrounding the protruding part, a connection part connecting the protruding part and the grounding part, and a plurality of groove parts extending between the protruding part and the outer periphery of the bottom side, the connection part being a curved surface that protrudes outward from the plastic bottle, the height of the end of the groove part on the outer periphery side of the bottom side relative to the grounding part is higher than the height of the protruding part relative to the grounding part, the plastic bottle is filled with contents, and the contents are frozen.

With this configuration, the plastic bottle is endowed with sufficient pressure resistance, making it easy to prevent deformation of the plastic bottle due to the rise in internal pressure that accompanies freezing of the contents. This allows filled products with frozen contents to be suitably used for distribution, etc. In addition, since the thickness of the plastic bottle can be reduced compared to conventional methods while maintaining pressure resistance, a filled product can be provided that conserves packaging resources.

The following describes preferred embodiments of the present invention. However, the scope of the present invention is not limited to the preferred embodiments described below.

In one embodiment of the plastic bottle according to the present invention, the diameter of the grounding portion is preferably 65% or more and 80% or less of the diameter of the outer periphery of the bottom surface.

This configuration makes it possible to provide a plastic bottle that is both pressure resistant and moldable, and can easily stand upright.

In one embodiment of the plastic bottle according to the present invention, it is preferable that the maximum circumferential width of each of the grooves is 7% or more and 21% or less of the outer periphery of the bottom surface.

This configuration makes it possible to provide a plastic bottle that is both pressure resistant and moldable, and also suitable for transportation.

In one embodiment, the plastic bottle of the present invention preferably weighs 14 g or more and 23 g or less.

This configuration makes it possible to provide a plastic bottle that is both pressure resistant and moldable, while also saving resources.

In one embodiment, the plastic bottle of the present invention preferably contains recycled materials.

This configuration makes it less likely that the appearance of the plastic bottle will be an issue in the application of the plastic bottle. In addition, there is greater freedom in the selection of raw materials.

Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments, which are given with reference to the drawings.

FIG. 1 is a front view of a plastic bottle according to a first embodiment. FIG. 2 is a front cross-sectional view of the bottom of the plastic bottle according to the first embodiment. FIG. 2 is a bottom view of the plastic bottle according to the first embodiment. FIG. 1 is a front cross-sectional view of the bottom of a plastic bottle according to the prior art FIG. 11 is a front view of a plastic bottle according to a second embodiment. FIG. 6 is a cross-sectional view of a plastic bottle according to a second embodiment (cross-sectional view taken along line VI-VI in FIG. 5). FIG. 7 is a cross-sectional view of a plastic bottle according to a second embodiment (cross-sectional view taken along line VII-VII in FIG. 5). FIG. 11 is a bottom view of a plastic bottle according to a second embodiment. 9 is a cross-sectional view of the bottom of a plastic bottle according to a second embodiment (cross-sectional view taken along line IX-IX in FIG. 8).

[First embodiment]
A first embodiment of a plastic bottle and a filled product according to the present invention will be described with reference to the drawings. In the following, an example in which the plastic bottle according to the present invention is applied to a plastic bottle 1 (hereinafter simply referred to as bottle 1) that is filled with a beverage and used will be described. In addition, an example in which the filled product according to the present invention is applied to a black tea beverage product in which the bottle 1 is filled with a beverage will also be described.

[Bottle composition]
As shown in Fig. 1, the bottle 1 according to this embodiment is a plastic bottle formed into a cylindrical shape with a bottom on the side of the bottom surface 2. More specifically, the bottle 1 includes a mouth portion 11, a shoulder portion 12 that is continuous with the mouth portion 11 and gradually expands in diameter toward the bottom surface 2, a cylindrical body portion 13 that is continuous with the shoulder portion 12, and a bottom portion 14 that is continuous with the body portion 13 (Fig. 1). The portion of the bottom portion 14 that comes into contact with the ground when the bottle 1 is placed is defined as the bottom surface 2.

The bottle 1 according to this embodiment is a so-called PET bottle. The bottle 1 is obtained by stretching a preform by a stretch molding method such as biaxial stretch blow molding. In this embodiment, the bottle 1 is made of polyethylene terephthalate. Note that, although polyethylene terephthalate is a typical material constituting the bottle 1, other plastic materials such as polyethylene and polypropylene may also be used. In addition, regardless of which plastic material is used, the origin is not limited, and it may be synthesized by a petrochemical process (so-called virgin material), derived from plant raw materials, derived from used containers, etc. (so-called recycled material), etc., or a mixture of these. Note that recycled material refers to a plastic material that is recycled into a usable raw material after being supplied to the market as a molded body such as a container or packaging material. Examples of such a recycling method include mechanical recycling and chemical recycling.

The capacity of bottle 1 is not particularly limited, and can be about 200 mL to 2 L, such as the commonly available 280 mL, 350 mL, or 500 mL, and is preferably 250 to 750 mL. In the following explanation, an example in which the full capacity of bottle 1 is 646 mL will be particularly described. In the illustrated example, the total height of bottle 1 is 209 mm, the diameter D1 of bottle 1 is 71.5 mm, and the circumference of bottle 1 is 225 mm.

Bottle 1 may be a thinner-walled bottle than conventional bottles. Specifically, the ratio of the weight (in g) of bottle 1 to the full capacity (in mL) of bottle 1 is preferably 0.022 g/mL or more and 0.092 g/mL or less, and more preferably 0.022 g/mL or more and 0.058 g/mL or less. When the ratio of weight to full capacity is within the above range, the amount of resin used can be sufficiently reduced while still ensuring appropriate strength, which contributes to resource conservation and weight reduction of bottle 1.

Bottle 1 according to this embodiment weighs 15 g. As described above, the full capacity of bottle 1 is 646 mL, so the ratio of the weight of bottle 1 to the full capacity of bottle 1 is 0.023. If bottle 1 weighs 14 g or more, as in this example, it is easy to ensure sufficient thickness of bottle 1, which is favorable from the standpoint of strength and yield. If bottle 1 weighs 23 g or less, it is favorable from the standpoint of resource conservation.

The desired weight of the bottle 1 can be produced by stretching a preform of the desired weight to produce the bottle 1. In other words, it is preferable to produce the bottle 1 using a preform weighing 14 g or more and 23 g or less.

The liquid contained in bottle 1 is not particularly limited, and examples include beverages such as soft drinks (carbonated drinks, fruit drinks, black tea drinks, coffee drinks, tea-based drinks, mineral water, soy milk, vegetable drinks, sports drinks, cocoa drinks, etc.), alcoholic drinks, milk drinks, liquid foods such as soups, and liquid seasonings such as sauces and soy sauces. Bottle 1 has a higher pressure resistance than conventional plastic bottles, so bottle 1 is less likely to break even if it is used to freeze the contents. This makes it suitable for distributing frozen beverages.

The configurations of the mouth 11, shoulder 12, and body 13 are similar to those used in conventional PET bottles, so detailed explanations will be omitted. The mouth 11 is a spout for pouring liquid and is provided with a male thread that can be screwed into a cap (not shown). The body 13 is configured in a cylindrical shape and is an area where a roll label can be affixed. The body 13 is provided with several circumferential grooves. The shoulder 12 continuously connects the mouth 11 and body 13.

In this embodiment, the bottom 14 and the body 13 are separated by a circumferential groove 15. In this embodiment, the circumferential groove 15 is provided in an area 13 to 16 mm high from the bottom surface 2. Note that in this embodiment, another circumferential groove 16 may be provided in the body 13. Furthermore, the body 13 and the bottom 14 are not necessarily separated by a circumferential groove. For example, the boundary between the body 13 and the bottom 14 can be defined as the position closest to the bottom surface 2 among the positions in the height direction where the diameter of the approximately cylindrical body 13 begins to decrease toward the bottom surface 2.

[Bottom configuration]
The bottom surface 2 is provided with a protruding portion 21, a grounding portion 22, a connecting portion 23, and a groove portion 24 (FIGS. 2 and 3). In FIG. 2, a plane on which the bottle 1 is placed, such as a desk, is shown as an imaginary plane P.

The protruding portion 21 is provided at a position in the center of the bottom surface 2, protruding from the grounding portion 22 toward the inside of the bottle 1. In this embodiment, the height H1 of the protruding portion 21 based on the imaginary plane P (which is synonymous with the height of the protruding portion 21 based on the grounding portion 22) is 6.7 mm. The protruding portion 21 is provided approximately parallel to the imaginary plane P, and therefore, when the bottle 1 is placed on a flat surface such as a desk, the protruding portion 21 and the flat surface are parallel. When viewed from the mouth 11 side, the protruding portion 21 is arranged concentrically with the bottom surface 2.

The grounding portion 22 is provided in a ring shape so as to surround the protruding portion 21. The grounding portion 22 is the area that actually comes into contact with a flat surface when the bottle 1 is placed on the flat surface such as a desk. Note that the above description that the bottom surface 2 comes into contact with the flat surface does not mean that the entire bottom surface 2 comes into contact with the flat surface, but rather that the grounding portion 22, which is a part of the bottom surface 2, comes into contact with the flat surface.

In this embodiment, the diameter D2 of the grounding portion 22 is 54.9 mm. Therefore, the diameter D2 of the grounding portion 22 is 77% of the diameter D1 (equal to the diameter D1 of the bottle 1) of the outer periphery 2a of the bottom surface 2 (an example of a circumscribing circle of the bottom surface). Note that the grounding portion 22 is divided by the groove portion 24 and does not form a continuous ring, but the diameter of the grounding portion 22 is taken as the diameter of an imaginary circle C including the divided portion.

As in this example, it is preferable that the diameter of the grounding portion 22 is 65% or more of the diameter of the outer periphery 2a of the bottom surface 2, since this makes it easier for the bottle 1 to stand independently stably. Also, if the diameter of the grounding portion 22 is 80% or less of the diameter of the outer periphery 2a of the bottom surface 2, defects such as holes being created in the bottom surface 2 (so-called bursts) are less likely to occur when manufacturing the bottle 1 by the stretch blow molding method, and this makes it easier to increase the yield of the bottle 1.

The connection portion 23 is a portion that connects the protruding portion 21 and the ground portion 22. More specifically, the connection portion 23 is formed as a curved surface that continuously connects the outer circumference of the protruding portion 21 and the ground portion 22, and the curved surface is convex on the outside of the bottle 1. This also contributes to avoiding defects such as bursting on the bottom surface 2. This is because the occurrence of bursting is typically caused by a decrease in temperature of the resin material that contacts the part corresponding to the bottom surface 2 of the mold during the stretch blow molding process, which impairs the fluidity and makes it difficult for the resin material to spread evenly over the entire bottom surface 2. However, by forming the connection portion 23 as a curved surface that is convex on the outside of the bottle 1, the protruding portion 21, the connection portion 23, and the ground portion 22 are continuously connected, making it easier for the resin material to flow smoothly.

The groove portion 24 is a groove-shaped portion extending between the protruding portion 21 and the outer periphery 2a of the bottom surface 2, and multiple groove portions 24 (eight in this embodiment) are provided radially. The groove portions 24 extend across the grounding portion 22 and the connecting portion 23. The end portion 24a of the groove portion 24 on the outer periphery 2a side of the bottom surface 2 is located at a height H2 (synonymous with the height based on the grounding portion 22) of 10 mm based on the imaginary plane P. Therefore, the height of the end portion 24a of the groove portion 24 is higher than the height of the protruding portion 21.

In addition, in this embodiment, the circumferential width of the groove portion 24 is maximum at the position where the groove portion 24 divides the ground contact portion 22. This width is 11.3 mm. Therefore, the maximum circumferential width W of the groove portion 24 is 5% of the length of the outer periphery 2a of the bottom surface 2 (equal to the periphery of the bottle 1). As in this example, if the maximum circumferential width W of the groove portion 24 is 5% or more of the length of the outer periphery 2a of the bottom surface 2, the pressure resistance of the bottom surface 2 is likely to be improved by the groove portion 24. Furthermore, if the maximum circumferential width W of the groove portion 24 is 7% or less of the length of the outer periphery 2a of the bottom surface 2, the width of the ground contact portion 22 can be sufficiently secured, so that the bottle 1 is likely to stand independently stably.

In this embodiment, the groove portion 24 is formed as a curved surface that continuously connects the outer periphery of the insertion portion 21 and the outer periphery 2a of the bottom surface 2, and the curved surface is convex toward the outside of the bottle 1.

In conventional bottles, the bottom surface 3 generally has the insertion portion 31 formed as a curved surface that is convex on the inside of the bottle (Figure 4). A convex shape on the inside of the bottle is advantageous in terms of resistance to the increase in internal pressure caused by the expansion of the contents, but is disadvantageous in terms of avoiding defects such as bursting at the bottom surface 3, since the structure makes it difficult for the resin to flow during the stretch blow molding process. In the bottle 1 according to this embodiment, the use of a curved surface that is convex on the outside of the bottle 1 improves moldability compared to conventional bottles, while at the same time realizing the same resistance as conventional bottles by making the height of the end 24a of the groove portion 24 higher than the height of the insertion portion 21.

[Beverage product composition and bottle function and effect]
The black tea beverage product (an example of a filled product) according to this embodiment is a product in which a black tea beverage (an example of a content) is filled in a bottle 1. The full capacity of the bottle 1 is 646 mL, and 600 mL of black tea beverage is filled at room temperature, giving a filling rate of 93%.

The black tea beverage product according to this embodiment is distributed, stored, and sold (hereinafter referred to as "distribution, etc.") in a frozen state.

Since black tea beverages are liquids whose main component is water, when they are frozen, their volume increases from the state before freezing. Therefore, in black tea beverage products that are distributed, the volume of the contents is larger than the volume (600 mL) at room temperature. The expansion of the black tea beverage caused by freezing generates stress from the inside to the outside of the bottle 1, but in the bottle 1 according to this embodiment, the bottom surface 2 is provided with the above-mentioned protruding portion 21, grounding portion 22, connecting portion 23, and groove portion 24, so that deformation due to this stress (so-called buckling) can be suitably suppressed. Therefore, it is difficult for the bottom surface 2 to protrude due to buckling, preventing the bottle 1 from standing up on its own. This allows the black tea beverage to be suitably distributed in a frozen state. In addition, the bottle 1 according to this embodiment is easy to thin while achieving the strength required for distribution in a frozen state.

The bottle 1 according to this embodiment is also suitable for thinning because it has a structure that makes it difficult for defects such as bursting to occur on the bottom surface 2 when the bottle 1 is manufactured by the stretch blow molding method. In other words, the bottle 1 is a plastic bottle that can be thinned while simultaneously achieving both strength for distribution in a frozen state and a high production yield, and can contribute to resource conservation.

[Second embodiment]
A second embodiment of the plastic bottle and filled product according to the present invention will be described with reference to the drawings. In the following, an example in which the plastic bottle according to the present invention is applied to a plastic bottle 4 (hereinafter simply referred to as bottle 4) that is filled with a beverage and used will be described. Note that the description of components common to the first embodiment will be omitted or simplified.

[Bottle composition]
As shown in Fig. 5, the bottle 4 according to this embodiment is a plastic bottle with a bottom surface 5 side formed in a cylindrical shape. More specifically, the bottle 4 includes a mouth portion 41, a shoulder portion 42 that is continuous with the mouth portion 41 and gradually expands in diameter toward the bottom surface 5, a cylindrical body portion 43 that is continuous with the shoulder portion 42, and a bottom portion 44 that is continuous with the body portion 43 (Fig. 5). The part of the bottom portion 44 that comes into contact with the ground when the bottle 4 is placed is defined as the bottom surface 5. In this embodiment, the boundary between the bottom portion 44 and the body portion 43 is defined as the height position at which the width of the bottle 4 starts to decrease toward the bottom surface 5 in a front view (Fig. 5) seen from a direction directly facing one surface of the body portion 43.

The body 43 is a generally rectangular cylinder, and is further divided into an upper portion 43a and a lower portion 43b. The upper portion 43a has a rectangular shape with rounded corners in cross section (Fig. 6). The lower portion 43b has a generally octagonal shape with a chamfered rectangle in cross section (Fig. 7). The body 43 is provided with a circumferential groove 45 that runs around the outer periphery of the body 43. The depth of each of the multiple circumferential grooves 45 can be determined independently.

The mouth 41 is a spout for pouring liquid and has a male thread that can be screwed into a cap (not shown). The upper portion 43a of the body 43 is rounded and is an area where a roll label can be attached. The lower portion 43b of the body 43 has an angular shape, which helps to prevent the bottle 4 from tipping over when transported on a conveyor or the like. The shoulder 42 continuously connects the mouth 41 and the body 43.

Bottle 4 is the same as bottle 1 according to the first embodiment in that it is a PET bottle, the materials that can be used, the available capacity, the wall thickness (the weight of bottle 4 relative to the full capacity), the weight of bottle 4, the manufacturing method of bottle 4, and the liquids that can be contained in bottle 4.

[Bottom configuration]
The bottom surface 5 is provided with a protruding portion 51, a grounding portion 52, a connection portion 53, and a groove portion 54 (FIG. 8). In FIG. 8, the plane on which the bottle 4 is placed, such as a desk, is shown as an imaginary plane P.

The protruding portion 51 is provided at a position in the center of the bottom surface 5, protruding from the grounding portion 52 toward the inside of the bottle 1. The protruding portion 51 is provided approximately parallel to the imaginary plane P, so that when the bottle 1 is placed on a flat surface such as a desk, the protruding portion 51 and the flat surface are parallel to each other.

The configuration of the grounding portion 52 is generally similar to that of the grounding portion 22 in the first embodiment, but the definition of the preferred range of the diameter of the grounding portion 52 is different. From the viewpoint of making the bottle 4 easier to stand on its own stably, it is preferable that the diameter of the grounding portion 52 is 65% or more of the diameter of the circumscribing circle of the bottom surface 2. From the viewpoint of improving the yield of the bottle 4, it is preferable that the diameter of the grounding portion 52 is 80% or less of the diameter of the circumscribing circle of the bottom surface 5.

The configuration of the connection portion 53 and the groove portion 54 is similar to that of the connection portion 23 and the groove portion 24 in the first embodiment.

[Bottle functions and effects]
The bottle 4 according to this embodiment has the same effect as the bottle 1 according to the first embodiment. That is, the bottle 4 is less likely to buckle at the bottom surface 5 when the beverage contained therein freezes, and is less likely to burst or have other defects during molding. The bottle 4 according to this embodiment is also suitable as a container for distributing beverages in a frozen state.

Other embodiments
Finally, other embodiments of the plastic bottle and filled product according to the present invention will be described. Note that the configurations disclosed in each of the following embodiments can be combined with the configurations disclosed in other embodiments as long as no contradiction occurs.

In the above first embodiment, a configuration in which the diameter of the grounding portion 22 is 77% of the diameter of the outer periphery 2a of the bottom surface 2 is described as an example, and it is stated that it is preferable for the diameter of the grounding portion to be 65% or more and 80% or less of the diameter of the outer periphery of the bottom surface. However, in the plastic bottle according to the present invention, the ratio of the diameter of the grounding portion to the diameter of the circumscribing circle of the bottom surface is not limited to the above range.

In the above first embodiment, a configuration in which the maximum circumferential width W of the groove portion 24 is 5% of the length of the outer periphery 2a of the bottom surface 2 is described as an example, and it is stated that it is preferable for the maximum circumferential width of the groove portion to be 5% or more and 7% or less of the length of the outer periphery of the bottom surface. However, in the plastic bottle according to the present invention, the ratio of the maximum circumferential width of the groove portion to the length of the outer periphery of the bottom surface is not limited to the above range.

In the above first embodiment, an example was described in which the weight of bottle 1 is 15 g, and it was stated that the weight of bottle 1 is preferably 14 g or more and 23 g or less. However, the weight of the plastic bottle according to the present invention is not limited to the above range.

As seen in the first and second embodiments above, the plastic bottle according to the present invention may be substantially cylindrical or substantially rectangular. It may also be of other shapes.

In the above first and second embodiments, the grounding portion is annular. However, in the present invention, the grounding portion only needs to be provided in a position that surrounds the protruding portion, and the shape of the grounding portion is not limited.

As for other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and that the scope of the present invention is not limited thereto. Those skilled in the art will easily understand that appropriate modifications are possible without departing from the spirit of the present invention. Therefore, other embodiments that are modified without departing from the spirit of the present invention are naturally included in the scope of the present invention.

The present invention will be further described below with reference to examples. However, the present invention is not limited to the following examples.

[Test 1: Burst resistance evaluation]
Example 1
A bottle having the same outer shape as the bottle 1 according to the first embodiment was molded using a preform weighing 15 g. At this time, the temperature conditions of the mold and the operating conditions of the stretch rod were adjusted to adjust the bottom weight to 0.9 g.

(Comparative Example 1)
A bottle was molded in the same manner as in Example 1, except that the outer shape of the bottom was made the same as that of the prior art bottle shown in FIG.

(evaluation)
100 bottles each of Example 1 and Comparative Example 1 were prepared, and the bottoms of each were visually observed. In Example 1, no bottles had burst. On the other hand, in the Comparative Example, bursts occurred in 40 bottles. That is, bursts occurred in 40% of the bottles in Comparative Example 1.

(Summary)
No burst occurred in Example 1, whereas 40% of the bottles in Comparative Example 1 burst. This indicates that the bottle shape of Example 1 is less likely to cause burst. In this test, the bottom weight (0.9 g) was set smaller than the bottom weight of a bottle normally distributed, in the hope of clearly showing the difference in the burst occurrence rate, and the test was carried out under conditions that tend to cause burst. It can be said that the bottle of Example 1 did not burst, despite the conditions being harsher than usual.

[Test 2: Buckling Resistance Evaluation (First Embodiment)]
Example 2
A bottle having the same outer shape as the bottle 1 according to the first embodiment was molded using a preform weighing 15.0 g. At this time, the temperature conditions of the mold and the operating conditions of the stretching rod were adjusted to adjust the bottom weight to 1.6 g. The molded bottle was filled with 600 mL of black tea beverage with a Brix value of 0, and the mouth was sealed with a cap. The bottle filled with the black tea beverage was left to stand at -17°C for 24 hours to completely freeze the black tea beverage, and a sample was obtained.

Example 3
Except for adjusting the bottom weight to 1.3 g, the test was conducted in the same manner as in Example 2. The bottom weight in Example 2 is an average bottom weight in a commonly distributed product in the combination of the preform weight, bottle shape, and bottle volume in Example 2, and the bottom weight in Example 3 is a minimum bottom weight in a commonly distributed product.

(evaluation)
Ten samples were prepared for each of Examples 2 and 3. Each sample was visually inspected to confirm the presence or absence of buckling, and the stability was evaluated when the sample was placed on a desk with the bottom part as the grounding surface. In Table 1, the evaluation results are shown in four levels, A to C, and the criteria for each level are as follows. Table 1 also shows the number of samples belonging to each level, A to C, for each example.
A: No buckling was observed with the naked eye, and the product stood stably on its own.
B: The bottle is wobbly when held upright, but does not tip over.
C: Bottles that are held upright may tip over.

Table 1: Buckling resistance evaluation (first embodiment)

(Summary)
No tipping of the frozen samples was observed for either the bottles of Example 2 or Example 3. In particular, since no tipping was observed even in Example 3, which has the lowest bottom weight for products normally distributed, it is expected that the bottle having the outer shape according to the above-mentioned first embodiment can be suitably used for the distribution of frozen products, etc.

[Test 3: Buckling Resistance Evaluation (Second Embodiment)]
Example 4
A bottle having the same outer shape as the bottle 4 according to the second embodiment was molded using a preform weighing 18.0 g. At this time, the temperature conditions of the mold and the operating conditions of the stretching rod were adjusted to adjust the bottom weight to 2.2 g. The molded bottle was filled with a sports drink having a Brix value of 4.45 ± 0.15 so that the head space volume was 29 mL, and the mouth was sealed with a cap. The head space volume is the volume of air present between the liquid level of the sports drink filled in the bottle and the cap. The bottle filled with the sports drink was left to stand at −17° C. for 24 hours, and the sports drink was completely frozen to obtain a sample.

Example 5
Except for adjusting the filling amount of the sports drink so that the head space volume was 23 mL, the test was performed in the same manner as in Example 4. The head space volume in Example 4 is an average value for a normally distributed product in the combination of the preform weight, bottle shape, and bottle volume in Example 4, and the head space volume in Example 5 is a minimum value for a normally distributed product.

Example 6
Except for adjusting the bottom weight to 1.9 g, the test was performed in the same manner as in Example 4. The bottom weight in Example 4 is the average bottom weight of a commonly distributed product in the combination of the preform weight, bottle shape, and bottle volume in Example 4, and the bottom weight in Example 6 is the minimum bottom weight of a commonly distributed product.

(Example 7)
The test was carried out in the same manner as in Example 6, except that the amount of the sports drink filled was adjusted so that the head space volume was 23 mL.

(evaluation)
Each of Examples 4 to 7 was evaluated in the same manner as in Test 2, except that three samples were prepared for each example.

Table 2: Buckling resistance evaluation (second embodiment)

(Summary)
No tipping of the frozen samples was observed for any of the bottles in Examples 4 to 7. In particular, no tipping was observed even in Examples 5 to 7, which were set under the conditions of the most stringent levels of bottom weight and head space volume from the viewpoint of buckling within the ranges that can actually be distributed, and therefore it is expected that the bottle having the outer shape according to the above-mentioned second embodiment can be suitably used for the distribution of frozen products, etc.

The present invention can be used, for example, in plastic bottles that are filled with beverages and beverage products in which the plastic bottles are filled with beverages.

[First embodiment]
1: Plastic bottle 11: Mouth 12: Shoulder 13: Body 14: Bottom 15: Circumferential groove 2: Bottom surface 2a: Outer circumference of bottom surface 21: Protruding portion 22: Grounding portion 23: Connection portion 24: Groove 24a: End of groove C: Imaginary circle P: Imaginary plane W: Maximum width of groove

[Second embodiment]
4: Plastic bottle 41: Mouth 42: Shoulder 43: Body 44: Bottom 45: Circumferential groove 5: Bottom surface 51: Insertion portion 52: Grounding portion 53: Connection portion 54: Groove portion

Claims (6)

A plastic bottle having a bottom side formed into a cylindrical shape with a bottom,
A protruding portion provided at the center of the bottom surface;
a grounding portion surrounding the protruding portion;
a connection portion that connects the insertion portion and the ground portion; and
a plurality of grooves extending between the protruding portion and an outer periphery of the bottom surface;
The connection portion is a curved surface that is convex toward the outside of the plastic bottle,
A plastic bottle in which the height of the end of the groove portion on the outer periphery of the bottom surface, taken from the ground contact portion, is higher than the height of the insertion portion, taken from the ground contact portion. The plastic bottle according to claim 1, wherein the diameter of the grounding portion is 65% to 80% of the diameter of the circumscribed circle of the bottom surface. The plastic bottle according to claim 1 or 2, wherein the maximum circumferential width of each of the grooves is 5% to 7% of the length of the circumference of the bottom surface. The plastic bottle according to claim 1 or 2, which has a weight of 14 g or more and 23 g or less. The plastic bottle according to claim 1 or 2, which contains recycled material. A plastic bottle having a bottom side formed into a cylindrical shape with a bottom,
A protruding portion provided at the center of the bottom surface;
a grounding portion surrounding the protruding portion;
a connection portion that connects the insertion portion and the ground portion; and
a plurality of grooves extending between the protruding portion and an outer periphery of the bottom surface;
The connection portion is a curved surface that is convex toward the outside of the plastic bottle,
The plastic bottle is filled with contents, and the height of the end of the groove portion on the outer circumferential side of the bottom surface with respect to the ground portion is higher than the height of the insertion portion with respect to the ground portion,
A filled product, the contents of which are frozen.