Patent Publication Number: US-9834358-B2

Title: Pressure reduction-absorbing bottle

Description:
TECHNICAL FIELD 
     The present invention relates to a pressure reduction-absorbing bottle. 
     Priority is claimed on Japanese Patent Application No. 2013-159077, filed Jul. 31, 2013, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     In the related art, a bottle is proposed which is formed of a synthetic resin material and into a cylindrical shape with a bottom (for example, refer to Patent Document 1). A bottom wall portion of a bottom portion of the bottle includes a grounding portion positioned at the outer circumferential edge of the bottom wall portion, a rising circumferential wall portion connecting to the inner side in the radial direction of the grounding portion and extending upward, an annular movable wall portion extending inward in the radial direction of the bottle from the upper end of the rising circumferential wall portion, and a recessed circumferential wall portion extending upward from the inner end in the radial direction of the movable wall portion. In addition, the movable wall portion rotates around the connection portion between the rising circumferential wall portion and the movable wall portion so as to move the recessed circumferential wall portion upward, and thereby pressure reduction inside the bottle can be absorbed. 
     In such a bottle, the body portion thereof may be formed having a smaller diameter than that of the bottom portion, for example, in order to improve the external appearance quality or attractiveness thereof, or in order to easily grasp the body portion. 
     DOCUMENT OF RELATED ART 
     Patent Document 
     [Patent Document 1] PCT International Publication No. WO 2010/061758 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, if the body portion of a bottle in the related art is formed having a small diameter, the volume of the body portion of the bottle decreases, and thus it is possible that pressure reduction absorption inside the bottle is not efficiently performed. 
     The present invention has been made in view of the above problems, and an object thereof is to provide a bottle in which a body portion is formed having a smaller diameter than that of a heel portion (a bottom portion) while appropriate pressure reduction-absorbing performance inside the bottle is maintained. 
     Solution to Problem 
     The present invention adopts the following means in order to solve the above problems. That is, a first aspect of the present invention is a pressure reduction-absorbing bottle including: a cylindrical shoulder portion; a cylindrical body portion connecting to a lower end of the shoulder portion; and a bottom portion formed in a cylindrical shape with a bottom and connecting to a lower end of the body portion. The bottom portion includes: a heel portion, an upper opening section of the heel portion being connected to a lower opening section of the body portion, and a bottom wall portion closing a lower opening section of the heel portion. The bottom wall portion includes: a grounding portion positioned at an outer circumferential edge of the bottom wall portion, a rising circumferential wall portion connecting to an inner side in a radial direction of the grounding portion and extending upward, an annular movable wall portion extending inward in the radial direction from an upper end of the rising circumferential wall portion, and a recessed circumferential wall portion extending upward from an inner end in the radial direction of the movable wall portion. The movable wall portion is arranged to be capable of rotating around a connection portion between the rising circumferential wall portion and the movable wall portion so as to move the recessed circumferential wall portion in an up-and-down direction. The body portion includes a straight cylindrical part connecting to the lower end of the shoulder portion and extending downward. The outer diameter of the straight cylindrical part is greater than or equal to 0.60 times the outer diameter of the heel portion and is smaller than the outer diameter of the heel portion. 
     In this case, the outer diameter of the straight cylindrical part is set to be smaller than the outer diameter of the heel portion, and thereby the external appearance of the bottle can be improved. In addition, the center of gravity of the bottle is lowered, and thus the bottle can independently and stably stand. Furthermore, the outer diameter of the straight cylindrical part is set to be greater than or equal to 0.60 times the outer diameter of the heel portion, and thereby the body portion of the bottle can secure a sufficient volume, appropriate pressure reduction-absorbing performance inside the bottle can be maintained, and thus pressure reduction absorption inside the bottle can be stably performed. Therefore, the external appearance of the bottle can be improved while appropriate pressure reduction-absorbing performance inside the bottle is maintained. 
     A second aspect of the present invention is that in the pressure reduction-absorbing bottle of the first aspect, the body portion is provided with two or more panel portions at intervals in a circumferential direction of the body portion, the panel portions being depressed inward in a radial direction of the body portion, and a pillar portion being formed between panel portions next to each other in the circumferential direction. The panel portion includes a panel bottom wall positioned at the inside of the panel portion in the radial direction, and a sidewall extending outward in the radial direction from an outer circumferential edge of the panel bottom wall. The panel bottom wall is provided with a rib formed between vertical sidewall parts of the sidewall intersecting with the circumferential direction, the rib projecting outward in the radial direction, and a gap being formed between the rib and each of the vertical sidewall parts. 
     In the second aspect of the present invention, the rigidity of the body portion increases by providing the panel portions in the body portion. Therefore, the movable wall portion can easily moves the recessed circumferential wall portion upward, and both of the body portion and the bottom portion can absorb pressure reduction. 
     Since the rib is arranged in the panel bottom wall, the inner side in the radial direction of a label attached covering the panel portions can be supported thereby. Accordingly, at the time the label is attached thereto, the label covering the body portion can be prevented from moving inward in the radial direction of the bottle, and can be maintained to be flat. That is, the label can be held along a circumferential line in the circumferential direction of the bottle. Therefore, creases occurring in the label due to the label being depressed inside a space (the space between a pair of vertical sidewall parts facing each other) can be limited, and deterioration of the external appearance quality of the label can be limited. 
     Since two or more panel portions are formed in the circumferential direction, four or more gaps in the circumferential direction are formed between ribs and vertical sidewall parts. Therefore, the body portion can deform to decrease the diameter thereof while the above gap is narrowed in the circumferential direction, sufficient pressure reduction-absorbing performance is not applied only to the bottom portion but can also be applied to the body portion. As a result, occurrence of corners in the body portion due to deformation of the body portion caused by compression during pressure reduction inside the bottle can be limited, and a favorable external appearance of the label can be reliably kept. 
     A third aspect of the present invention is that in the pressure reduction-absorbing bottle of the second aspect, the rib is formed on the entire length of the panel bottom wall in a bottle axis direction. 
     In the third aspect of the present invention, since the rib is formed on the entire range in the up-and-down direction of the panel bottom wall, the rib is connected to areas within the body portion other than areas in which the panel portions are provided. Thus, in the section in which the label and the rib overlap with each other when being seen in the radial direction, the entire range of the label in the up-and-down direction can be supported. Therefore, creases occurring in the label can be reliably prevented. Furthermore, a wide support area of the body portion for the label can be formed by the ribs and the pillar portions, and deterioration of the external appearance quality of the label can be reliably prevented. 
     A fourth aspect of the present invention is that in the pressure reduction-absorbing bottle of the second or third aspect, an outer surface of a top wall of the rib is positioned on an edge of an imaginary circle in a horizontal cross section of the body portion parallel to the radial direction, the imaginary circle being formed by connecting outer surfaces of top parts of a plurality of pillar portions in the circumferential direction, and the top parts being positioned at the outside of the pillar portions in the radial direction. 
     In the fourth aspect of the present invention, the outer surface of the top wall of the rib is positioned on the edge of the imaginary circle formed by connecting the outer surfaces of the top parts of the plurality of pillar portions in the circumferential direction, the top parts being positioned at the outside of the pillar portions in the radial direction. Therefore, the label can be reliably held along the imaginary circle. Thus, a smooth circumferential surface of the label can be formed in the circumferential direction of the bottle. 
     A fifth aspect of the present invention is that in the pressure reduction-absorbing bottle of any one of the first to fourth aspects, the body portion includes a lower body part extending downward from a lower end of the straight cylindrical part and connecting to an upper end of the heel portion, and the outer diameter of the lower body part gradually increases downward. 
     In the fifth aspect of the present invention, since the outer diameter of the lower body part connecting the straight cylindrical part and the heel portion gradually increases downward, the external appearance of the body portion can be further enhanced, and the blow moldability of the body portion can be improved. In addition, since the lower body part smoothly connects the straight cylindrical part and the heel portion which have different outer diameters, a user can easily grasp the body portion, and creases occurring in a label attached to the straight cylindrical part can be further reliably prevented. 
     Effects of Invention 
     According to a bottle of the present invention, the outer diameter of the straight cylindrical part is set to be smaller than the outer diameter of the heel portion, and thereby the external appearance and self-standing stability of the bottle are improved. In addition, the outer diameter of the straight cylindrical part is set to be greater than or equal to 0.60 times the outer diameter of the heel portion, and thereby appropriate pressure reduction-absorbing performance inside the bottle can be maintained, and the pressure reduction absorption of the bottle can be stably performed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side view showing a bottle of an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view taken along II-II line in  FIG. 1 . 
         FIG. 3  is a bottom view showing the bottle of  FIG. 1 . 
         FIG. 4  is a cross-sectional view taken along IV-IV line in  FIG. 3 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of a bottle of the present invention is described with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately adjusted in order to show each member in a recognizable size. 
     As shown in  FIG. 1 , a bottle  1  (a pressure reduction-absorbing bottle) of this embodiment includes a cylindrical mouth portion  11 , a cylindrical shoulder portion  12 , a cylindrical body portion  13 , and a bottom portion  14  formed in a cylindrical shape with a bottom. The mouth portion  11 , the shoulder portion  12 , the body portion  13  and the bottom portion  14  are schematically configured to be connected together in this order in a state where the central axes thereof are positioned coaxially with a common axis. Hereinafter, the common axis is referred to as a bottle axis O, in  FIG. 1 , a side of the bottle close to the mouth portion  11  in a direction parallel to the bottle axis O is referred to as an upper side, another side thereof close to the bottom portion  14  in the direction is referred to as a lower side, a direction orthogonal to the bottle axis O is referred to as a radial direction, and another direction around the bottle axis O is referred to as a circumferential direction. 
     The bottle  1  is integrally formed of a synthetic resin material, and is formed by blow-molding (for example, biaxial stretch blow molding) a preform formed in a cylindrical shape with a bottom through injection molding. The internal capacity of the bottle  1  of this embodiment is set to be, for example, 150 to 1000 ml. 
     The mouth portion  11  is attached with a cap  15 . 
     The shoulder portion  12  connects to the lower end of the mouth portion  11  and extends downward. The outer diameter of the shoulder portion  12  gradually increases downward. 
     The body portion  13  connects to the lower end of the shoulder portion  12  and extends downward. The body portion  13  includes a straight cylindrical part  21  connecting to the lower end of the shoulder portion and extending downward, and a lower body part  22  formed in a truncated conical cylindrical shape, connecting to the lower end of the straight cylindrical part  21 , and extending downward. 
     The outer diameter of the straight cylindrical part  21  is a nearly fixed value on the entire length thereof in the up-and-down direction. The straight cylindrical part  21  is wound with a label (not shown) such as a shrink label. The shrink label is formed in a cylindrical shape of a heat-shrinkable resin film or the like, and is brought into close contact with the outer surface of the straight cylindrical part  21  by heat-shrinking the label. Accordingly, in order to prevent creases or the like on the shrink label after attachment, the inner side in the radial direction of the label has to be appropriately supported by the bottle. 
     As shown  FIGS. 1 and 2 , the straight cylindrical part  21  is provided with a plurality of panel portions  31  (five panel portions in this embodiment) at intervals in the circumferential direction, and the panel portions  31  are depressed inward in the radial direction of the bottle and are used for pressure reduction absorption. Part of the straight cylindrical part  21  positioned between panel portions  31  next to each other in the circumferential direction forms a pillar portion  32  extending in the up-and-down direction. That is, the panel portions  31  and the pillar portions  32  are alternately arranged in the circumferential direction in the straight cylindrical part  21 . The panel portions  31  extend in the up-and-down direction within an area other than two end parts in the up-and-down direction of the straight cylindrical part  21 . 
     The panel portion  31  is formed of a panel bottom wall  33  and a sidewall  34 . The panel bottom wall  33  is positioned on the inside in the radial direction of an outer circumferential surface (for example, a top part  32   a  of the pillar portion  32  described later) of the body portion  13 , and the sidewall  34  extends outward in the radial direction from the outer circumferential edge of the panel bottom wall  33 . 
     A pair of vertical sidewall parts  34   a  within the sidewall  34  connect to two ends in the circumferential direction of the panel bottom wall  33 , and extend in the up-and-down direction (that is, the vertical sidewall parts  34   a  intersect with the circumferential direction of the bottle). As shown in  FIG. 2 , the pair of vertical sidewall parts  34   a  incline so that the separation between the pair of vertical sidewall parts  34   a  of one panel portion  31  facing each other gradually increases from the inside to the outside in the radial direction of the bottle. In addition, the vertical sidewall part  34   a  may not incline but may be configured to extend in the radial direction. The pillar portion  32  positioned between vertical sidewall parts  34   a  of panel portions  31  next to each other in the circumferential direction is formed in a rectangular shape or in a trapezoid shape in a horizontal cross section orthogonal to the bottle axis O. The top part  32   a  positioned on the outside in the radial direction of the pillar portion  32  is formed having a curved surface projecting outward in the radial direction, and the straight cylindrical part  21  has the maximum outer diameter at the top parts  32   a.    
     A pair of horizontal sidewall parts  34   b  are positioned at two ends in the up-and-down direction of the sidewall  34  and extend in the circumferential direction. The pair of horizontal sidewall parts  34   b  are inclined surfaces which incline so that the separation between the pair of horizontal sidewall parts  34   b  gradually increases from the inside to the outside in the radial direction of the bottle. 
     As shown in  FIGS. 1 and 2 , a central part in the circumferential direction of the panel bottom wall  33  is provided with a vertical rib (a rib)  35  projecting outward in the radial direction of the bottle. The vertical rib  35  is arranged between a pair of vertical sidewall parts  34   a  included in one panel portion  31 , a gap  36  is formed between the vertical rib  35  and each of the pair of vertical sidewall part  34   a  in the circumferential direction, and the vertical rib  35  is formed on the entire length in the up-and-down direction of the panel bottom wall  33 . That is, the vertical rib  35  is connected to two ends in the up-and-down direction of the straight cylindrical part  21 . Thus, in the central part in the circumferential direction of the panel portion  31 , the vertical rib  35  bridges a pair of horizontal sidewall parts  34   b  facing each other in the up-and-down direction, and areas positioned on two sides in the circumferential direction of the vertical rib  35  are configured as a pair of gaps  36  extending in the up-and-down direction. In this case, the gaps  36  are positioned between outer ends in the circumferential direction of the panel portion  31  and outer ends in the circumferential direction of the vertical rib  35 , and thus two gaps  36  are provided in each panel portion  31 . Accordingly, since five panel portions  31  are provided in the straight cylindrical part  21  in this embodiment, a total of ten gaps  36  are arranged at intervals in the circumferential direction. 
     Although the vertical rib  35  of this embodiment is formed on the entire length in the up-and-down direction of the panel bottom wall  33 , the present invention is not limited to this configuration, and a gap may be formed between the vertical rib  35  and the horizontal sidewall part  34   b . That is, the vertical rib  35  extending in the up-and-down direction may not be connected to two ends in the up-and-down direction of the straight cylindrical part  21 . 
     The vertical rib  35  is formed of a top wall  35   a  positioned on the outside in the radial direction of the panel bottom wall  33 , and circumferential end walls  35   b  connecting outer ends in the circumferential direction of the top wall  35   a  to the panel bottom wall  33 . 
     As shown in  FIG. 2 , in a horizontal cross section parallel to the radial direction, the top wall  35   a  is formed having a curved surface projecting outward in the radial direction. The top walls  35   a  are substantially positioned on the edge of an imaginary circle L (on the circumference of the imaginary circle L), the edge of the imaginary circle L extending in the circumferential direction of the bottle in accordance with the surface shape of each top part  32   a  of the plurality of pillar portions  32 , and the straight cylindrical part  21  has the maximum outer diameter at the top walls  35   a.    
     The present invention is not limited to this configuration, and the top wall  35   a  may be disposed at a position different from the circumference of the imaginary circle L extending in the circumferential direction of the bottle in accordance with surface shapes of the plurality of top parts  32   a . In this case, it is preferable that the top walls  35   a  be arranged at positions in which the top walls  35   a  and the top parts  32   a  can appropriately support the inner side in the radial direction of a label (a shrink label) attached to the straight cylindrical part  21 . 
     As shown in  FIGS. 1 and 2 , the circumferential end walls  35   b  are positioned at two ends in the circumferential direction of the vertical rib  35  and extend in the up-and-down direction. The circumferential end walls  35   b  incline so that the separation between the pair of circumferential end walls  35   b  gradually increases from the outside to the inside in the radial direction of the bottle. Thus, in a horizontal cross section parallel to the radial direction, the vertical rib  35  is formed in a trapezoid shape whose width in the circumferential direction gradually increases from the outside to the inside in the radial direction of the bottle. 
     Each of the pillar portion  32  and the vertical rib  35  is arranged to be line symmetry with respect to a center line extending in the radial direction through the center of each of the pillar portion  32  and the vertical rib  35 . That is, the positions of inner ends in the radial direction of a pair of circumferential end walls  35   b  included in one vertical rib  35  are equivalent to each other in the radial direction, and the length in the radial direction of each of the pair of vertical sidewall parts  34   a  included in one pillar portion  32  is less than that of the circumferential end wall  35   b.    
     A connection part  37  of the panel portion  31  connects the inner end in the radial direction of the vertical sidewall part  34   a  and the inner end in the radial direction of the circumferential end wall  35   b  to each other. Specifically, in a horizontal cross section parallel to the radial direction, a pair of connection parts  37  included in one panel portion  31  incline so that the separation between the pair of connection parts  37  gradually decreases from the outside to the inside in the radial direction of the bottle. In addition, the gap  36  is formed by the vertical sidewall part  34   a , the horizontal sidewall parts  34   b , the connection part  37 , and the circumferential end wall  35   b.    
     The vertical sidewall parts  34   a  incline so that the separation between the vertical sidewall parts  34   a  gradually increases from the inside to the outside in the radial direction of the bottle, and the connection parts  37  also incline so that the separation between the connection parts  37  gradually increases from the inside to the outside in the radial direction of the bottle. However, the inclination angles of the vertical sidewall part  34   a  and the connection part  37  are different from each other. As shown in  FIG. 2 , an angle formed between the vertical sidewall part  34   a  and a circumferential line extending in the circumferential direction of the bottle is set to be greater than another angle formed between the connection part  37  and the circumferential line. In other words, the end (the end close to the pillar portion  32 ) of the connection part  37  positioned on the outside in the radial direction of the bottle is connected to the end of the vertical sidewall part  34   a  positioned on the inside in the radial direction of the bottle via a bending part which bends from the end of the connection part  37  toward the outside in the radial direction of the bottle. 
     When the internal pressure of the bottle  1  is reduced, a force is added to the vertical rib  35  inward in the radial direction of the bottle, and then the force is transmitted to the connection part  37  connected to the vertical rib  35  (the circumferential end wall  35   b ). Since the connection part  37  is connected to the vertical sidewall part  34   a  via the above bending part, when the force is added thereto, the connection part  37  is moved so that an angle (the angle on the outside in the radial direction of the bottle) between the connection part  37  and the vertical sidewall part  34   a  increases. In other words, when the force is added thereto, the connection part  37  is moved so that the connection part  37  and the vertical sidewall part  34   a  are arranged in a straight line. Since the connection part  37  and the vertical sidewall part  34   a  are connected via the above bending part, the connection part  37  can easily move when a force during pressure reduction is added, and thus the vertical rib  35  supported by the connection parts  37  can be appropriately moved inward in the radial direction of the bottle. That is, the panel portion  31  can be configured as an auxiliary pressure reduction-absorbing portion next to a bottom wall portion  43  (described later, a movable wall portion  62 ). 
     Each of the inner and outer diameters of the lower body part  22  gradually increases downward, and a connection section between the lower body part  22  and the straight cylindrical part  21  is provided with a first annular groove  38  on the entire circumference of the connection section. 
     As shown in  FIGS. 1 and 4 , the bottom portion  14  includes a cylindrical heel portion  41  and the bottom wall portion  43 . An upper opening section of the heel portion  41  is connected to a lower opening section of the body portion  13 . The bottom wall portion  43  closes a lower opening section of the heel portion  41 , and the outer circumferential edge of the bottom wall portion  43  serves as a grounding portion  42 . 
     The heel portion  41  includes a lower heel part  51  connecting to the outer side in the radial direction of the grounding portion  42 , and an upper heel part  52  connecting to the lower end of the body portion  13 . In this embodiment, the outer diameter D 1  of the straight cylindrical part  21  is greater than or equal to 0.60 times the outer diameter D 2  of the heel portion  41  and is smaller than the outer diameter D 2  of the heel portion  41 . 
     The outer diameters of the lower and upper heel parts  51  and  52  are equivalent to each other, and the bottle  1  has the maximum outer diameter at the lower and upper heel parts  51  and  52 . In addition, if the outer diameter D 1  of the straight cylindrical part  21  is greater than or equal to 0.60 times the maximum outer diameter of the heel portion  41  and is smaller than the maximum outer diameter of the heel portion  41 , the outer diameters of the lower and upper heel parts  51  and  52  may be different from each other. A connection section between the lower and upper heel parts  51  and  52  is provided with a second annular groove  53  on the entire circumference of the connection section. 
     As shown in  FIGS. 3 and 4 , the bottom wall portion  43  includes a rising circumferential wall portion  61  connecting to the inner side in the radial direction of the grounding portion  42  and extending upward, an annular movable wall portion  62  projecting from the upper end of the rising circumferential wall portion  61  toward the center in the radial direction of the bottle, a recessed circumferential wall portion  63  extending upward from the inner end in the radial direction of the movable wall portion  62 , and a top wall portion  64  connected to the upper end of the recessed circumferential wall portion  63 . 
     As shown in  FIG. 4 , the rising circumferential wall portion  61  has a diameter which gradually decreases from the lower side to the upper side of the rising circumferential wall portion  61 . As shown in  FIGS. 3 and 4 , the rising circumferential wall portion  61  is provided with an uneven portion  61   a  on the entire circumference of the rising circumferential wall portion  61 . The uneven portion  61   a  includes a plurality of projections  61   b  which are arranged at intervals in the circumferential direction. The projection  61   b  projects inward in the radial direction of the bottle and is formed having a curved surface. 
     The movable wall portion  62  is formed having a curved surface convex downward, and extends so that the separation between the movable wall portion  62  and a plane positioned above the movable wall portion  62  and being perpendicular to the bottle axis O gradually increases from the outside to the inside in the radial direction of the movable wall portion  62 . The movable wall portion  62  and the rising circumferential wall portion  61  are connected via a first curved surface part  65   a  projecting upward. The movable wall portion  62  is configured to rotate around the first curved surface part  65   a  (which is a connection portion between the rising circumferential wall portion  61  and the movable wall portion  62 ) so as to move the recessed circumferential wall portion  63  upward. 
     As shown in  FIG. 3 , a plurality of bottom ribs  66  are radially arranged in the movable wall portion  62  around the bottle axis O. The bottom rib  66  includes a plurality of recesses  66   a  which are arranged at intervals in the radial direction and are depressed upward to have a curved surface. 
     As shown in  FIGS. 3 and 4 , the recessed circumferential wall portion  63  is arranged coaxially with the bottle axis O, and is formed in a multi-stage cylindrical shape whose diameter gradually increases from the upper side to the lower side of the recessed circumferential wall portion  63 . Specifically, the recessed circumferential wall portion  63  includes a lower cylindrical part  67  whose diameter gradually decreases upward from the inner end in the radial direction of the movable wall portion  62 , an upper cylindrical part  68  whose diameter gradually increases downward from the outer circumferential edge of the top wall portion  64  and is smaller than that of the lower cylindrical part  67 , and a stepped part  69  connecting the lower and upper cylindrical parts  67  and  68 . 
     The lower cylindrical part  67  is connected to the inner end in the radial direction of the movable wall portion  62  via a second curved surface part  65   b  projecting downward. The second curved surface part  65   b  obliquely projects downward and inward in the radial direction of the bottle. The lower cylindrical part  67  is formed in a circular shape in a horizontal cross section parallel to the radial direction. 
     The upper cylindrical part  68  is provided with a plurality of projecting parts  68   a  at intervals in the circumferential direction, the projecting part  68   a  projecting inward in the radial direction of the bottle. In a bottom view, the projecting part  68   a  is formed having a curved surface convex outward in the radial direction of the bottle. The outer end in the radial direction of the projecting part  68   a  connects to the stepped part  69 . As shown in  FIG. 4 , in a vertical cross section parallel to the bottle axis O direction, the projecting part  68   a  is formed having a curved surface convex inward in the radial direction of the bottle. As shown in  FIG. 3 , an intermediate part  68   b  positioned between projecting parts  68   a  next to each other is formed having a curved surface projecting outward in the radial direction of the bottle in a bottom view, and connects ends in the circumferential direction of projecting parts  68   a  to each other, the projecting parts  68   a  being next to each other in the circumferential direction. As shown in  FIGS. 3 and 4 , the projecting parts  68   a  and the intermediate parts  68   b  form a polygonal cylindrical part  68   c  having a polygonal shape (an equilateral triangle cylindrical shape) in which an intermediate part  68   b  between projecting parts  68   a  next to each other in the circumferential direction is set to be a corner (a vertex), and a projecting part  68   a  is set to be a side. 
     The stepped part  69  is formed having a concave curved surface depressed outward in the radial direction of the bottle. The stepped part  69  is positioned above or at an equivalent height to the upper end of the rising circumferential wall portion  61 . 
     The top wall portion  64  is formed in a circular shape in a plan view arranged coaxially with the bottle axis O. The top wall portion  64  and the recessed circumferential wall portion  63  as a whole are formed in a cylindrical shape with a top. 
     When the pressure inside the bottle  1  having the above configuration reduces, in the bottom portion  14  of the bottle  1 , the movable wall portion  62  rotates around the first curved surface part  65   a  which is the connection portion between the rising circumferential wall portion  61  and the movable wall portion  62 , thereby moving the recessed circumferential wall portion  63  upward. In addition, the body portion  13  deforms to decrease the diameter thereof while the gap  36  between the pillar portion  32  and the vertical rib  35  is narrowed in the circumferential direction. Therefore, both of the bottom portion  14  and the body portion  13  absorb pressure reduction inside the bottle  1 . 
     According to the bottle  1  having the above configuration, the outer diameter of the straight cylindrical part  21  is set to be greater than or equal to 0.60 times the outer diameter of the heel portion  41  and to be smaller than the outer diameter of the heel portion  41 , and thus, while appropriate pressure reduction-absorbing performance inside the bottle  1  is maintained, the external appearance quality and attractiveness of the bottle  1  can be enhanced, and the self-standing stability thereof can be improved. 
     The rigidity of the body portion  13  can be increased by providing the panel portions  31  in the body portion  13 . Accordingly, the movable wall portion  62  can easily move the recessed circumferential wall portion  63  upward, and thus pressure reduction absorption is performed at both of the body portion  13  and the bottom portion  14 . In addition, since the rigidity of the body portion  13  increases, at the time of pressure reduction inside the bottle, the pressure reduction absorption can be primarily performed at the bottom portion  14 , and can be secondarily performed at the body portion  13 . Furthermore, since the vertical rib  35  arranged in the panel bottom wall  33  supports a label attached to the panel portion  31 , the label can be held to be flat, and thus creases occurring in the label can be limited. Therefore, deterioration of the external appearance quality of the label can be reliably prevented. 
     Since two or more and five or less panel portions  31  are formed, sufficient pressure reduction-absorbing performance can be applied to the body portion  13 , and a favorable external appearance of the label can be further reliably kept. 
     Since the straight cylindrical part  21  and the heel portion  41  are connected through the lower body part  22 , the external appearance of the body portion  13  can be further enhanced, and the blow moldability of the body portion  13  can be improved. 
     The inventor of the present invention has tested how the pressure reduction-absorbing performance of the bottle  1  is changed in accordance with the ratio of the outer diameter D 1  of the straight cylindrical part  21  and the outer diameter D 2  of the heel portion  41 . 
     Hereinafter, sample bottles which were used for this test are described. The shapes and thicknesses of the bottom portions  14  of all the sample bottles were the same. The outer diameters D 1  of the straight cylindrical parts  21  were different between the samples 1 to 3, and the numbers of the panel portions  31  were different between the samples 1 and 4 to 6. The absorbing volume shown in the following table 1 is a value showing the volume inside a bottle immediately before the shape of the bottle cannot be maintained due to crush or bending of the bottle when the pressure inside the bottle is reduced. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 SAMPLE 
                 SAMPLE 
                 SAMPLE 
                 SAMPLE 
                 SAMPLE 
                 SAMPLE 
               
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 D1 [mm] 
                 46.7 
                 57.5 
                 35.0 
                 46.7 
                 46.7 
                 46.7 
               
               
                 D2 [mm] 
                 57.5 
                 57.5 
                 57.5 
                 57.5 
                 57.5 
                 57.5 
               
               
                 D2 − D1 [mm] 
                 10.8 
                 0 
                 22.5 
                 10.8 
                 10.8 
                 10.8 
               
               
                 D1/D2 
                 0.81 
                 1 
                 0.61 
                 0.81 
                 0.81 
                 0.81 
               
               
                 THE NUMBER OF 
                 5 
                 5 
                 5 
                 4 
                 3 
                 2 
               
               
                 PANEL PORTIONS 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 ABSORBING 
                 TOTAL [ml] 
                 10.9 
                 12.6 
                 9.3 
                 11.1 
                 10.3 
                 9.7 
               
               
                 VOLUME 
                 BODY 
                 4.9 
                 6.9 
                 3.0 
                 4.9 
                 4.2 
                 3.9 
               
               
                   
                 PORTION [ml] 
               
               
                   
                 BOTTOM 
                 6.0 
                 5.7 
                 6.3 
                 6.2 
                 6.1 
                 5.8 
               
               
                   
                 PORTION [ml] 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 PRESSURE REDUCTION 
                 24.2 
                 20.6 
                 28.6 
                 26.6 
                 26.3 
                 22.0 
               
               
                 INTENSITY [kPa] 
               
               
                   
               
            
           
         
       
     
     As shown in the table 1, in a case where the outer diameter D 1  of the straight cylindrical part  21  is set to be smaller than the outer diameter D 2  of the heel portion  41 , although the absorbing volume becomes less than that of another case where the outer diameter D 1  is set to be equivalent to the outer diameter D 2  (D 1 /D 2 =1, refer to the sample 2), the pressure reduction intensity is increased. 
     Since the shapes and thicknesses of the bottom portions  14  of all the samples are the same, the absorbing volumes of the bottom portions  14  are nearly equivalent. However, the higher the pressure reduction intensity of the body portion  13  is, the more easily the movable wall portion  62  moves the recessed circumferential wall portion  63  upward, and thus the more the total absorbing volume of the bottle  1  is increased. In addition, since the body portion  13  is provided with the panel portions  31 , the rigidity of the body portion  13  is increased, and both of the body portion  13  and the bottom portion  14  can absorb pressure reduction. 
     The more the outer diameter D 1  of the straight cylindrical part  21  decreased, the more the absorbing volume reduced. In addition, the more the number of the panel portions  31  was decreased, the more the absorbing volume reduced. With regard to the relationship between the number of the panel portions  31  and the absorbing volume, there was no significant difference between the case of five panels and the case of four panels, but the absorbing volume reduced by 14.3% in the case of three panels, and reduced by 20.4% in the case of two panels. However, a sufficient absorbing volume was secured in each case. Although deformation slightly occurred in an upper part of the pillar portion  32  of the samples 1, 2 and 4, and slightly occurred in the lower body part  22  of the samples 3 to 5, since a sufficient absorbing volume was secured in the bottle  1 , it is understood that the pressure reduction occurring inside the bottle  1  was sufficiently absorbed. 
     In a case where the outer diameter D 1  of the straight cylindrical part  21  was less than or equal to, for example, 34.0 mm and the ratio of the outer diameter D 1  of the straight cylindrical part  21  to the outer diameter D 2  of the heel portion  41  was less than 0.60, the blow moldability of the bottle  1  was low. 
     The present invention is not limited to the above embodiment, and various modifications can be adopted within the scope of the present invention. 
     For example, the outer diameters of the straight cylindrical part and the heel portion may be appropriately changed as long as the ratio of the outer diameter of the straight cylindrical part to the outer diameter of the heel portion is greater than or equal to 0.60 and is less than 1. 
     Although the panel portion is provided in an area other than two end parts in the up-and-down direction of the body portion, the panel portion may be provided on the entire length in the up-and-down direction of the straight cylindrical part. 
     Although one vertical rib is arranged in the panel bottom wall, a plurality of vertical ribs may be arranged at intervals within the panel bottom wall. 
     Although the number of the panel portions provided in the body portion is 2 or more and 5 or less, another number may be adopted, and no panel portion may be provided therein. 
     The body portion may be provided with no lower body part, and may be provided with a connection part which is formed in an annular shape in a plan view and connects the lower end of the straight cylindrical part and the upper end of the heel portion to form a stepped shape. For example, the connection part is arranged to be parallel to a plane perpendicular to the bottle axis O. In addition, the outer diameter of the straight cylindrical part may not be completely a fixed value on the entire length in the up-and-down direction of the straight cylindrical part, but may gradually and slightly decrease (for example, by about 1.5 mm) downward. For example, polyethylene terephthalate, polyethylene naphthalate, non-crystalline polyester, or a blended material thereof may be appropriately used for the synthetic resin material forming the bottle. 
     The bottle is not configured as only a single-layer structure but may also be configured as a laminated structure including an intermediate layer. The intermediate layer includes a layer formed of a resin material having a gas barrier property, a layer formed of a recycled material, a layer formed of a resin material having oxygen absorbency, and the like. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be applied to a bottle in which a body portion is formed having a smaller diameter than that of a heel portion while appropriate pressure reduction-absorbing performance inside the bottle is maintained. 
     DESCRIPTION OF REFERENCE SIGNS 
     
         
           1  bottle 
           11  mouth portion 
           12  shoulder portion 
           13  body portion 
           14  bottom portion 
           21  straight cylindrical part 
           22  lower body part 
           31  panel portion 
           32  pillar portion 
           32   a  top part 
           33  panel bottom wall 
           34  sidewall 
           34   a  vertical sidewall part 
           35  vertical rib (rib) 
           35   a  top wall 
           36  gap 
           41  heel portion 
           42  grounding portion 
           43  bottom wall portion 
           61  rising circumferential wall portion 
           62  movable wall portion 
           63  recessed circumferential wall portion 
         L imaginary circle 
         O bottle axis