Patent Description:
In freeze-storing a plastic bottle containing beverage, in association with expansion of the beverage involving phase change thereof from liquid to solid, there sometimes occurs a buckling phenomenon involving outward protrusive deformation of the bottom portion of the plastic bottle.

For preventing such buckling phenomenon, at the bottom portion of the conventional plastic bottle for freeze storage of beverage, there is provided a structure similar to a petaloid shape. This structure referred to as petaloid profile is employed in pressure-resistant PET bottles for carbonated drinks and resists the internal pressure due to carbon dioxide gas, thereby to prevent deformation of the PET bottle. The document <CIT> shows a plastic container being composed of a neck, a shoulder, a body and a base section, where the base section comprises at least two tie members extending from a central area to the side wall of the base. According to the invention, the tie members and/or the function of the tie members of the base at least in certain areas extend into the body section or into the body and the shoulder section of the plastic container.

The thermal expansion coefficient of beverage due to freeze-storage is higher with non-sugared (no sugar-added) drink than with sugared (sugar-added) drink. With the conventional plastic bottle, while suppression of the buckling phenomenon may be possible with the sugared drink, the suppression is difficult to achieve with non-sugared drink. An obvious conceivable solution for the suppression of the buckling phenomenon would be increase of the amount of resin used in the plastic bottle for desired increase of strength of the entire plastic bottle. However, in accordance with ever increasing need for resource and cost saving, there is a need for reduction in the weight and thickness of the plastic bottle.

In view of the above, it is desired to realize a plastic bottle that can effectively resist occurrence of the buckling phenomenon at the time of freeze-storage of non sugared drink while achieving yet desirable weight and thickness reduction of the plastic bottle.

A plastic bottle according to the present invention, as disclosed in claim <NUM>, provided as a plastic bottle having a cylindrical bottom portion, comprises:.

With the above-described configuration, by providing the deepest parts of the plurality of valley portions provided in the bottom portion in the arc form, it is possible to promote uniform dispersion of expansion pressure from the beverage at the time of its freeze-storage such that the pressure at the time of expansion were supported, as if, by a partial spherical face including the deepest parts of the plurality of valley portions. Consequently, even in the case of freeze-storage of non sugared beverage having high expansion coefficient, the buckling phenomenon hardly occurs. Moreover, thanks to the setting of the maximum circumferential length of the ground-contacting portion which comes into contact with a mounting surface such as a desk greater than the maximum circumferential length of the valley portion, toppling of the bottle will hardly occur at the time of conveying thereof by means of a conveyer or the like.

In the present invention, preferably, three ground-contacting portions are provided with an approximately equal circumferential spacing therebetween.

With the above-described arrangement of providing three ground-contacting portions, it is possible to secure a larger ground-contacting area than the conventional petaloid arrangement having five such ground-contacting portions. As a result, the possibility of toppling of the bottle at the time of e.g. conveying thereof by a conveyer or the like can be further reduced and it becomes also possible to achieve favorable moldability or formability of the bottom portion.

In the present invention, preferably, the bottle further comprises a plurality of groove portions extending from the side face via the ground-contacting portion to the bottom face, the groove portions being provided with an approximately equal circumferential spacing therebetween in the ground-contacting portion.

With the above-described arrangement, at the time of molding, sterilization, etc. of the plastic bottle, occurrence of sink marks therein can be suppressed even when the plastic bottle is designed for its weight and thickness reduction.

In the present invention, preferably, at least one of the plurality of groove portions extends to the vicinity of the center portion of the bottom face.

With the above-described inventive arrangement, as at least one of the plurality of groove portions extends to the vicinity of the center portion of the bottom face, the possibility of occurrence of the buckling phenomenon can be reduced even more effectively.

In the present invention, preferably, the bottom face has a partial spherical shape that protrudes inwards.

With the above-described inventive arrangement, there is no shape referred to as a dome portion protruding to the inner side of the bottom which portion would be provided at the center portion of the bottom face of the conventional plastic bottle. For this reason, no portion tending to invite stress concentration is present in the bottle, so that the stress concentration can be lessened effectively. Thus, even when the plastic bottle is dropped accidentally, the bottle can effectively withstand its impact, so that breakage of the bottom is prevented.

In the present invention, preferably, the plastic bottle is used for freezing.

With the above-described arrangement, the invention can be applied to a plastic bottle for freezing, so that even when the bottle is frozen, its deformation can be suppressed and this bottle is convenient also for carrying by a user.

Next, an embodiment of the present invention will be explained with reference to the accompanying drawings.

As shown in <FIG>, a plastic bottle <NUM> relating to this embodiment includes a neck portion <NUM> serving as a mouth or spout for dispensing liquid and a bottle main body portion <NUM> to be filled with liquid.

The bottle main body portion <NUM> includes a shoulder portion <NUM> formed continuously from the neck portion <NUM> and having a diameter which progressively increases in the direction toward a body portion <NUM>, the cylindrical body portion <NUM> formed continuously from the shoulder portion <NUM> and a cylindrical bottom portion <NUM> forming the bottom of the plastic bottle <NUM>.

An upper portion <NUM> of the body portion <NUM> provides a label-affixing area in which a roll label is to be affixed and includes a plurality of circumferential grooves <NUM> for reinforcement. In a lower portion <NUM> of the body portion <NUM>, there is formed an uneven face <NUM> having a plurality of circumferential grooves in curved forms, with taking into consideration reinforcement, readiness of user's holding of the bottom and aesthetic respect also.

Incidentally, what is referred to as the "bottom portion <NUM>" in this embodiment means the portion of the plastic bottle <NUM> excluding the neck portion <NUM>, the shoulder portion <NUM> and the body portion <NUM>. In the instant embodiment, a portion slightly upwards from starting positions of valley portions <NUM> to a ground-contacting portions <NUM> is the bottom portion <NUM> and a vertical length of this bottom portion <NUM> (the height measured from the ground-contacting portion <NUM> to the borderline between the side face <NUM> and the body portion <NUM>) can be set to e.g. from <NUM> to <NUM>.

As shown in <FIG>, <FIG>, the bottom portion <NUM> includes a plurality of valley portions <NUM> protruding inwards from the side face <NUM> of the bottom portion <NUM> to the vicinity of the center of the bottom face <NUM> and a plurality of ground-contacting portions <NUM> which come into contact with a mounting surface such as a desk. In the bottom portion <NUM> of this embodiment, three ground-contacting portions <NUM> are provided in an approximately equal spacing therebetween in the circumferential direction and between two ground-contacting portions <NUM> adjacent each other in the circumferential direction, one valley portion <NUM> is provided.

As shown in <FIG>, in the bottom portion <NUM>, the plurality of ground-contacting portions <NUM> are positioned on a same circumference of the outermost circumferential portion of the bottom face <NUM>. A maximum circumferential length L1 of the ground-contacting portion <NUM> varies in accordance with a maximum circumferential length L2 of the valley portion <NUM>. Yet, in this particular embodiment, as shown in <FIG>, the maximum circumferential length L1 of the ground-contacting portion <NUM> is set longer than the maximum circumferential length L2 of the valley portion <NUM> (L1>L2).

Incidentally, the shape of the ground-contacting portion <NUM> is not limited to the particular shape shown in <FIG> and <FIG> and the magnitude of its radial width may be set as desired.

As shown in <FIG>, the deepest part of the valley portion <NUM> extends continuously in a form of an outwardly convex arc <NUM> from the vicinity of the center of the bottom face <NUM> upwardly to the side face <NUM>. Incidentally, the term "upwardly" in the language of upwardly from the center of the bottom face <NUM> refers to the side where the neck portion <NUM>, the shoulder portion <NUM> and the body portion <NUM> are present as seen from the bottom face <NUM> of the plastic bottle <NUM>.

The deepest part of the valley portion <NUM> in this embodiment extends to the center portion of the bottom face <NUM>. However, this is not limiting. If the deepest part of the valley portion <NUM> is closer to the center portion of the bottom face <NUM>, the shape will approximate a spherical shape suitable for stress dispersion, so the effect of suppressing the buckling phenomenon will increase. However, it should be noted that the sole requirement for the deepest part of the valley portion <NUM> is its arrival at the bottom face <NUM>, while its extension to the vicinity of the center portion of the bottom face <NUM> is not an absolute requirement.

As shown in <FIG> and <FIG>, the bottom face <NUM> provided in this embodiment is a partial spherical shape protruding inwards. The deepest part of the valley portion <NUM> extends continuously in the form of a smooth arc <NUM> from the top portion of the bottom face <NUM> to the side face <NUM> of the bottom portion <NUM>.

In the bottom face <NUM> provided in this embodiment, there is no shape referred to as a "dome portion" protruding to the inner side of the bottom which portion would be provided at the center portion of the bottom face of the conventional plastic bottle. For this reason, no portion tending to invite stress concentration is present in the bottle, so that the stress concentration can be lessened effectively. Thus, even when the plastic bottle <NUM> is dropped accidentally, the bottle can effectively withstand its impact and breakage of the bottom can be prevented.

Forming the deepest parts of the plurality of valley portions <NUM> provided in the bottom portion <NUM> in the form of arcs <NUM> facilitates uniform dispersion of the expansion pressure of the beverage at the time of its freezing, providing a condition in which the inner pressure is supported by a partial spherical face including the deepest parts of the plurality of valley portions <NUM> (see <FIG>). Thus, even in the case of freezing of non sugared beverage having a high expansion coefficient, the buckling phenomenon would hardly occur. Moreover, since the maximum circumferential length L1 of the ground-contacting portion <NUM> which come into contact with a mounting surface such as a desk greater than the maximum circumferential length of the valley portion <NUM>, toppling would hardly occur either at the time of conveyance of a conveyer or the like.

As shown in <FIG>, a height H1 of the valley portion <NUM> can be set within a range from <NUM> to <NUM> for example. If this height H1 of the valley portion <NUM> is too large, this will lead to deterioration in the moldability and also greater possibility of toppling due to the corresponding decrease in the area of the ground-contacting portion <NUM>, conversely, if the height H1 is too small, the buckling phenomenon would occur more likely. Thus, the height should be set with consideration to these respects. The height H1 of the valley portion <NUM> which can achieve more favorable results in all of the respects of the moldability, the toppling resistance, the buckling phenomenon resistance ranges from <NUM> to <NUM>, especially preferable from <NUM> to <NUM>.

Incidentally, advantageously, the curvature radius of the arc <NUM> of the deepest part of the valley portion <NUM> should be such an amount that can ensure favorable effect against the internal pressure and favorable bottle moldability. Specifically, the curvature radius range advantageously from about <NUM> (R40) to about <NUM> (R60).

Further, by providing three ground-contacting portions <NUM>, it becomes possible to increase the ground-contacting area than the case of the conventional petaloid profile having five ground-contacting portions <NUM>. As a result, the possibility of toppling at the time of conveyance by a conveyer or the like can be even lessened and favorable moldability of the bottom portion <NUM> can be ensured more easily. However, the number of the ground-contacting portions <NUM> is not limited to the above, but may be changed as desired with consideration to such factors as the moldability, the toppling resistance, the buckling phenomenon resistance, etc..

As shown in <FIG>, <FIG>, three groove portions <NUM> extending from the side face <NUM> of the bottom portion <NUM> via the ground-contacting portion <NUM> to the bottom face <NUM> are provided with an approximately equal spacing therebetween in the circumferential direction in the ground-contacting portion <NUM>. With the above-described arrangement, at the time of molding, sterilization, etc. of the plastic bottle <NUM>, formation of sink marks can be suppressed even when the plastic bottle <NUM> is designed positively for its weight and thickness reduction. The number of such groove portions <NUM> is not limited to the above, but may be changed as desired with consideration to such factors as the moldability, the sink mark formation suppressing effect, etc. However, in the case of this particular embodiment, when two groove portions <NUM> are provided, the possibility of formation of the sink marks will be higher; and when four groove portions <NUM> are provided, it will become difficult to obtain favorable moldability.

As shown in <FIG> and <FIG>, in this embodiment, in each one ground-contacting portion <NUM>, three groove portions <NUM> are provided with the approximately equal spacing in the circumferential direction and only the groove portion <NUM> located at the center among them extends to the vicinity of the center of the bottom face <NUM>. As the grooves portion <NUM> extends to the vicinity of the center of the bottom face <NUM>, this arrangement can further reduce the possibility of the buckling phenomenon. Although it is possible to extend all of the plurality of groove portions <NUM> to the vicinity of the center portion; however, if such factors as the moldability, etc. are considered, it is advantageous that at least one of the plurality of groove portions <NUM> extends to the vicinity of the center portion. And, taking such factors as described above, the number of the groove portions <NUM> to be extended to the vicinity of the center of the bottom face <NUM> may be changed suitably.

In this embodiment, the circumferential length of the groove portion <NUM> is set shorter than the maximum circumferential length of the valley portion <NUM>.

As shown in <FIG>, according to the invention, a bottom-up height H2 (height from the ground-contacting portion <NUM> to the center portion of the bottom face <NUM>) ranges from <NUM> to <NUM>, from the viewpoints of effective suppression of the buckling phenomenon, the favorable moldability of the bottle and readiness to prevent bottle breakage at time of dropping.

The liquid to be filled in the plastic bottle <NUM> of this embodiment is not particularly limited. The liquid can be e.g. any drink such as drinking water, tea, juice, coffee, chocolate drink, soft drink, alcoholic drink, milk beverage, soup, or any liquid seasoning such as Worcestershire sauce, soy sauce, etc. Further, in the case of beverage or drink in particular, it may be sugared drink or non-sugared drink. In the case of freezing of non-sugared drink, the plastic bottle <NUM> of this embodiment can be suitably used.

The plastic bottle <NUM> of this embodiment can be used for any use such as normal temperature use, refrigerating use, freezing use, but it may be used for freezing particularly suitably.

The plastic bottle <NUM> of this embodiment can be integrally molded by a stretch molding technique such as the biaxial stretch blow molding technique, with using, as a principal material thereof, a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, etc. The capacity of the plastic bottle <NUM> is not particularly limited, but can be approximately from <NUM> milliliters to <NUM> liters which are commonly used, especially preferably from <NUM> milliliters to <NUM> liter.

The plastic bottle <NUM> of this embodiment can be formed thinner than the standard plastic bottle for beverage, for the sake saving of material and cost. Specifically, preferably, the ratio of the amount of resin (g) used the plastic bottle <NUM> relative to the overflow capacity (ml) of the plastic bottle <NUM> ranges from <NUM> to <NUM> (g/ml), more preferably, from <NUM> to <NUM>. If the ratio of the resin amount relative to the overflow capacity exceeds <NUM> (g/ml), such bottle can no longer be classified as a thin and light-weight bottle. Conversely, if the ratio of the resin amount relative to the overflow capacity falls below <NUM> (g/ml), the thickness will be too small to ensure sufficient strength.

Claim 1:
Aplastic bottle (<NUM>) for freezing, the plastic bottle (<NUM>) having a cylindrical bottom portion (<NUM>), comprising:
a plurality of valley portions (<NUM>) protruding inwards from a side face (<NUM>) to a bottom face (<NUM>) of the bottom portion (<NUM>); and
a plurality of ground-contacting portions (<NUM>);
wherein a maximum circumferential length (L1) of the ground-contacting portion (<NUM>) is set greater than a maximum circumferential length (L2) of the valley portion (<NUM>); and
wherein the deepest part of the valley portion (<NUM>) forms an outwardly convex arc (<NUM>) extending continuously upwards from the bottom face (<NUM>) to the side face (<NUM>), characterized in that
the bottom face (<NUM>) has a partial spherical shape that protrudes inwards, characterized in that a height (H2) from the ground-contacting portion (<NUM>) to a center portion of the bottom face (<NUM>) is from <NUM> to <NUM>.