Plastic bottle

Abstract

A hot-fill type plastic bottle having a body, wherein said body has a octagonal cross-sectional shape, each of corners of the octagon is formed with a ridge wall, connecting walls are provided at both lateral sides of each of the ridge walls to form a pillar, a pressure reduction absorbing portion is formed between any two adjacently located ones of the ridge walls, and two connecting walls of one of the pillars form an angle between 60 and 115°. The rigidity of the pillar is raised. The bottle shows a pressure reduction absorbing effect similar to that of a conventional hexahedral bottle. In addition, the wide area of the shrink-wrap type label can be seen at a glance.

Description

BACKGROUND OF THE INVENTION

[0001] This invention relates to a plastic bottle and, more particularly, to a hot-fill type plastic bottle.

[0002] Plastic bottles provided at the body thereof with pressure reduction absorbing portions for hot-fill the liquid content are known. Hexahedral bottles having a body whose corners are rounded are marketed.

[0003] However, when a shrink label is applied to the peripheral wall of a known hexahedral bottle, the label is inevitably divided by six.

[0004] If a design, a mark, an explanation of the goods or the like is printed on two of six lateral surfaces of the bottle, such design or the like can be viewed at a glance when the viewer sees it along the radial line of the bottle. However, if the design or the like is printed on three or more of six lateral surfaces, the viewer can no longer see it at a glance, and has to rotate the bottle to entirely understand what is printed there.

[0005] In order to freely design the mark or the like, and in order to recognize the design or the like at a glance, it may be considered to increase the number of lateral side to make the bottle almost cylindrical. However, as the number of lateral side increases, the pressure reduction absorbing portion area of the bottle is reduced to consequently reduce the pressure reduction absorbing effect thereof. Such a bottle can no longer be used for hot-fill applications. It is commonly believed that the maximal number of lateral sides of a polyhedral bottle is six if it is used for hot-fill applications.

SUMMARY OF THE INVENTION

[0006] In view of the above problem, it is therefore the object of the present invention to provide a hot-fill type bottle having a body with a relatively large number of lateral sides so as to make the wrap film of the bottle to be easily viewed particularly in terms of design and printing, and to show a pressure reduction absorbing effect similar to that of conventional hexahedral bottles.

[0007] According to the invention, the above object is achieved by providing a hot-fill type plastic bottle having a body, wherein said body has a octagonal cross-sectional shape, each of corners of the octagon is formed with a ridge wall, connecting walls are provided at both lateral sides of each of the ridge walls to form a pillar, a pressure reduction absorbing portion comprises a pressure reduction absorbing wall and the connecting wall, and is formed between any two adjacently located ones of the ridge walls, and two connecting walls of one of the pillars form an angle between 60 and 115°.

[0008] Preferably, each of the pressure reduction absorbing walls is provided with a ridge-shaped or groove-shaped rib.

[0009] The present invention provides the following advantages.

[0010] As described above, according to the invention, the octagonal body is provided with the pillar at each of corners of the octagon, each of the pillars comprises the ridge wall and the connecting walls at both lateral sides of the ridge wall, and the connecting walls form the angle between 60 and 115°. Thus, the rigidity of the pillar is raised. In addition, since the pressure reduction absorbing portion is formed between any two adjacently located ones of the ridge walls, the bottle shows a pressure reduction absorbing effect similar to that of a conventional hexahedral bottle.

[0011] In addition, since the ridge wall is provided, the wide area of the shrink-wrap type label can be seen at a glance.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a schematic front view of an embodiment of bottle according to the invention.

[0013] FIG. 2 is a schematic cross sectional view of the bottle of FIG. 1 taken along line A-A in FIG. 1.

[0014] FIG. 3 is an enlarged schematic view of a pressure reduction absorbing portion of the embodiment of FIG. 1.

[0015] FIG. 4 is a graph of the pressure reduction absorbing effect of the embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Now, the present invention will be described by referring to the accompanying drawings that illustrate preferred embodiments of the invention.

[0017] Referring to FIG. 1, illustrating an embodiment of bottle according to the invention, a bottle “A” is a hot-fill type bottle made of synthetic resin such as PET, and is formed by oriented-blow molding to show an octagonal body.

[0018] The bottle “A” comprises a neck 1, a shoulder 2, a body 3 showing an octagonal cross section, and a bottom 4. An outer periphery of the neck 1 is formed with a thread 5. A neck ring 6 is projected outwardly under the thread 5.

[0019] A horizontal rib 7 is formed between the body 3 and the shoulder 2. A narrow strip 8 is arranged under the horizontal rib 7. A horizontal rib 9 is formed between the body 3 and the bottom 4. A narrow strip 10 is arranged on the horizontal rib 9.

[0020] The body 3 extends between the upper strip 8 and the lower strip 10. The body 3 has a substantially octagonal cross sectional shape. Each of the corners of the octagon is formed with a ridge wall 11 axially extended. Each of the ridge wall 11 has an outwardly protruded or rounded cross sectional shape, and connects to the upper strip 8 and the lower strip 10. A pressure reduction absorbing portion 12 is formed between any two adjacently located ones of the ridge walls 11.

[0021] Each of the pressure reduction absorbing portions 12 comprises a pressure reduction absorbing wall 16, and a connecting wall 14 which connects the pressure reduction absorbing wall 16 and the ridge wall 11. More specifically, the connecting wall 14 connects with the upper strip 8 and the lower strip 10, and also with an edge 13 of one of the ridge walls 11 and an edge 13 of the adjacent ridge wall 11. In other words, at both lateral sides of each of the ridge walls 11, two connecting walls 14 are provided. The pressure reduction absorbing wall 16 connects with inner edges 15a, 15b, 15c, 15d of the connecting wall 14. Each of the pressure reduction absorbing wall 16 is somewhat outwardly protruded or curved.

[0022] While the wall 16 is slightly outwardly curved in the illustrated embodiment, it may alternatively be completely flat.

[0023] The pressure reduction absorbing wall 16 is formed with a rib 17. In the illustrated embodiment, the rib 17 is concaved, extends axially along the ridge walls 11, and has an inverted U-shape at the top thereof and a U-shape at the bottom thereof. Although the rib 17 is a groove shaped rib in the illustrated embodiment, it may be a ridge-shaped rib.

[0024] The bottom 4 comprises a bottom peripheral wall 20 extending downwardly from the horizontal rib 9, a bottom end wall 21, and a bottom wall 22 upwardly concaved from the bottom end wall 21.

[0025] The bottom peripheral wall 20 is provided at a middle section thereof with a horizontal rib 23, and the bottom wall 22 is provided with a plurality of radially -extending reinforcement ribs of a known type.

[0026] Now, the more detailed structure, the function and the effect of the ridge walls 11 and the pressure reduction absorbing portions 12 of the body 3 will be described by referring to FIG. 3.

[0027] Each of the ridge walls 11 and the connecting walls 14a, 14b axially provided adjacent to each of the ridge walls 11 form a pillar which raises the rigidity of the body. The connecting wall 14a and the connecting wall 14b define a pillar angle &agr;.

[0028] In this embodiment, the pillar angle &agr; is between 60° and 115°, preferably not smaller than 75°.

[0029] The bottle of this embodiment is made of 32 g or less of synthetic resin, and has a capacity of 500 ml. Each of the ridge walls 11 of the illustrated embodiment has the outwardly curved surface, which curvature has 68 mm of a diameter “D”. Each of the ridge walls 11 has a width “w” of 5.35 mm. Any two adjacently located ones of the ridge walls 11 are separated by a distance “W” of 21 mm. As described above, the pressure reduction absorbing wall 16 is outwardly curved, and thus has a diameter. The difference (or a height in a diametrical direction) “H” of the diameter “D” of the ridge walls 11 and the diameter of the pressure reduction absorbing wall 16 is 2.99 mm.

[0030] It should be noted, however, that the above described values of the dimensions of the body of the bottle can be modified appropriately according to the capacity and the profile of the bottle and according to the diameter of the ridge wall.

[0031] Preferably, the dimension can vary according to the following relationship.

[0032] W=1/3.5D to 1/2.8D

[0033] H=1/25D to 1/15D

[0034] w=1 to 6 mm

[0035] In the case of conventional bottles having a hexagonal body, the pillar angle &agr; was between 0 and 45°, and the pressure reduction absorbing effect was about 30 cc. On the other hand, according to the above described embodiment of the present invention, the pillar angle &agr; is between 60° and 115°, preferably not smaller than 75°, which is larger than that of the conventional bottle. Thus, the pillars show an improved rigidity, and, in addition, the bottle shows a pressure reduction absorbing effect substantially same as that of a hexahedral bottle.

[0036] Additionally, since each of the pressure reduction absorbing walls 16 is provided with the rib 17, it can be formed stably without deformation of the wall 16. In addition, the rib 17 reinforces the pressure reduction absorbing 16 and the connecting walls 14, so that the rigidity of the pillars in an axial direction of the container (buckling strength) is increased as a result of the reinforcement of the connecting walls 14.

[0037] Now, the present invention will be described by way of experiments to illustrate the function and the effect of the invention.

[0038] [Experiments]

[0039] 32 g of preforms made of PET resin were biaxially oriented blow molded to form five bottles having a capacity of 529 ml and an octagonal body.

[0040] Each of the bottles had the following dimensions; D=68 mm, H=2.99 mm, W=21 mm, w=5.35 mm. The pillar angle of the bottles was differentiated to produce five different types having respective pillar angles of 15°, 40°, 60°, 75° and 95°.

[0041] Each of the bottles without the liquid content was subjected to thermal conditions equivalent to those of actual hot-fill operations (87° C. of water was filled, cooled and then removed), and then filled with water. The bottles filled with water were hermetically sealed at the neck, and subsequently the content was reduced by means of a syringe needle at a constant rate, to observe the limit capacity until which the pillars could maintain the proper profile (pressure reduction absorbing effect).

[0042] Table 1 and the graph of FIG. 4 summarily shows the obtained results. 1 TABLE 1 The Relationship between the Pillar Angle and the Pressure Reduction Absorbing Effect pillar angle pressure reduction absorbing effect (cc) 15 15.0 40 20.0 60 24.5 75 27.3 95 29.8

[0043] As seen from the results, it is recognized that if the pillar angle &agr; is 75° or more, the rigidity of the pillars of a bottle according to the invention was improved, so as to show a pressure reduction absorbing effect similar to that of a hexahedral bottle.

[0044] It will be appreciated from the graph of FIG. 4 that the bottle with the pillar angle &agr; of 115° has the pressure reduction absorbing effect greater than that of the bottle with the pillar angle &agr; of 75°.

[0045] The bottle with a pillar angle of 60° shows a pressure reduction absorbing effect that is lower than that of a bottle with a pillar angle of 75° only by 10%, and hence is acceptable.

[0046] While the above described bottles had specific values for H, W and w, it was also proved that a similar pressure reduction absorbing effect can be obtained when H=1/25 to 1/15D and W=1/3.5 to 1/2.8D.

[0047] While the present invention is described above by way of an embodiment having an octagonal body, a bottle according to the invention may alternatively have a heptagonal or nonagonal body.

Claims

1. A hot-fill type plastic bottle having a body, wherein

said body has a octagonal cross-sectional shape,

each of corners of the octagon is formed with a ridge wall,

connecting walls are provided at both lateral sides of each of the ridge walls to form a pillar,

a pressure reduction absorbing portion comprises a pressure reduction absorbing wall and the connecting wall, and is formed between any two adjacently located ones of the ridge walls, and

two connecting walls of one of the pillars form an angle between 60 and 115°.

2. The hot-fill type plastic bottle according to

claim 1, wherein each of the pressure reduction absorbing walls is provided with a ridge-shaped or groove-shaped rib.