JP2015160650A - plastic bottle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic bottle capable of ensuring bendability and suppressing the deformation of a bottom part as well as the occurrence of stress crack even when the bottle is reduced in size and weight.SOLUTION: A bottom part 5 of a plastic bottle 1 comprises: a central recess part 20 in which the central part of the bottom part 5 is recessed upward in a substantially hemispherical shape; an annular ground contact part 22 which leads to the outside portion of the central recess part 20; and an inclined heel part 24 which connects the outside portion of the ground contact part 22 to the lower part of a trunk part 4 in a circumferential direction of the bottle. A plurality of recessed ribs 30 are formed in the circumferential direction of the bottle so as to longitudinally traverse a boundary 40 between the heal part 24 and the trunk part 4.

Description

  The present invention relates to a bottom structure of a plastic bottle (hereinafter also simply referred to as “bottle”).

  Since a plastic bottle filled with a carbonated beverage is required to have pressure resistance, generally, a plastic container having a petaloid shape at the bottom of a cylindrical container is used (see, for example, Patent Documents 1 and 2).

  In recent years, from the viewpoint of environmental considerations, it has been promoted to reduce the amount of resin used as a bottle material resource as much as possible, thereby reducing the weight of the bottle.

Japanese Patent Laid-Open No. 7-165224 JP-A-7-300121

  As carbonated beverage-based bottles, a large size exceeding 1 L and a medium size of 500 ml are mainstream, but if a smaller size (for example, 280 ml) with a smaller capacity can be provided, differentiation from other companies' products can be achieved. However, if the current carbonated beverage-based bottle is reduced in size as it is, the vendorability (vending machine adaptability) is lacking. This is because the petaloid-shaped bottle has a large ratio of the bottom height to the total bottle height, so the straight length of the trunk (the length between the uppermost maximum diameter portion and the lower maximum diameter portion) This is because a sufficient amount cannot be secured.

  In view of such circumstances, the present inventor examined the shape of a so-called champagne base in which the bottom central portion was raised in a substantially hemispherical shell shape as the bottom structure of a pressure-resistant small bottle, and the bottle ( It was confirmed that the bottom part) was elongated in the vertical direction and stress cracks were generated. As a countermeasure against such a phenomenon, a method of increasing the thickness of the bottle can be taken, but this does not lead to weight reduction of the bottle. Therefore, further improvements were sought.

  An object of the present invention is to provide a plastic bottle that can ensure bendability even when it is reduced in size and weight, and can suppress the deformation of the bottom and the occurrence of stress cracks.

  In order to achieve the above object, the plastic bottle of the present invention is a plastic bottle having a bottom portion connected to the body portion, and the bottom portion has a central recess portion formed by recessing the center portion of the bottom portion upward in a substantially hemispherical shape. An annular grounding part connected to the outer part of the central recess part, and an inclined heel part that connects the outer part of the grounding part to the lower part of the body part in the bottle circumferential direction, and the boundary between the heel part and the lower part of the body part Are provided with a plurality of concave ribs formed in the circumferential direction of the bottle.

  According to the present invention, since the bottom structure of the so-called champagne base is formed, the ratio of the bottom height to the total bottle height can be reduced as compared with the petaloid shape. Therefore, since the straight length of the trunk portion can be increased, bendability can be ensured. In addition, the strength of the bottom structure of the champagne base can be reinforced by the plurality of concave ribs. Specifically, since a plurality of concave ribs are formed at the boundary position between the inclined or curved heel portion and the lower portion of the trunk portion, the internal pressure can be released in the direction of the concave rib. . Thereby, the elongation to the vertical direction of the bottle (bottom part) by an internal pressure can be suppressed. At the same time, the occurrence of stress cracks can be suppressed. Therefore, the small lightweight bottle with the bendability suitable for filling the carbonated beverage can be provided.

  According to a preferred aspect of the present invention, each rib bottom surface of the plurality of concave ribs may extend so as to chamfer the boundary.

  By carrying out like this, the reinforcement effect by a concave rib can be heightened further compared with the case where it is set as the rib bottom face along each shape of the heel part and the lower part of a trunk | drum. In particular, since the concave ribs in the champagne base can function like valleys between the legs in the petaloid shape, the internal pressure can be distributed based on the same principle as the petaloid shape.

  According to a preferred aspect of the present invention, it is preferable that the lower ends of the plurality of concave ribs exist in the heel portion and do not reach the ground contact portion and the central recess portion.

  As described above, although the concave rib suppresses the occurrence of stress cracks, the concave rib that is too long can cause stress cracks on the contrary. In this regard, as described above, by preventing the concave ribs from extending in the subsequent inner region including the grounding portion, it is possible to achieve both balance of suppression of bottle deformation and suppression of occurrence of stress cracks in a balanced manner. .

  According to a preferred aspect of the present invention, the plurality of concave ribs may be formed at equal intervals in the bottle circumferential direction.

  By doing this, the bottom structure of the champagne base can be evenly reinforced in the bottle circumferential direction, so that further suppression of longitudinal elongation of the bottle (bottom part) due to internal pressure and suppression of occurrence of stress cracks can be achieved. Can be planned.

  According to a preferred aspect of the present invention, the plastic bottle has an internal volume of 200 to 300 ml, and the plurality of concave ribs may be 6 to 10.

  According to the analysis result of the present inventor, it was found that when the number of the concave ribs is less than 6, the amount capable of absorbing the longitudinal extension of the bottle (bottom part) due to the internal pressure is easily reduced. Further, it was found that when the number of the concave ribs exceeds 10, adverse effects are easily exerted on the stress cracks. This adverse effect on stress cracks is thought to be caused by a decrease in wall thickness per unit area when stretch blow molding from a preform to a bottle. In this regard, as in the above configuration, by optimizing the number of concave ribs in a small-sized bottle, both the suppression of the longitudinal elongation of the bottle (bottom) due to internal pressure and the suppression of the occurrence of stress cracks are balanced. can do.

(A) And (b) is the perspective view which looked at the plastic bottle which concerns on embodiment from another angle, respectively. (A) is the front view of the plastic bottle of FIG. 1, (b) is the side view seen from the angle shifted 22.5 degrees from (a). (A) And (b) is the longitudinal cross-sectional view cut | disconnected by the IIIa-IIIa line | wire and IIIb-IIIb line | wire of Fig.2 (a), respectively. It is the cross-sectional view cut | disconnected by the IV-IV line of Fig.3 (a).

A plastic bottle according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.
In the following description, the direction where the bottle bottom is present is defined as the lower side, and the direction where the bottle mouth is present is defined as the upper side. A transverse section means a sectional shape in a plane perpendicular to the central axis of the bottle, and a vertical section means a sectional shape in a plane including the central axis of the bottle.

  As shown in FIGS. 1 to 3, the plastic bottle (hereinafter referred to as “bottle 1”) has a mouth portion 2, a shoulder portion 3, a trunk portion 4 and a bottom portion 5 in order from the upper side. These portions (2, 3, 4 and 5) are integrally formed and constitute a bottomed cylindrical bottle wall for storing carbonated beverages therein. The bottle 1 is a small-sized bottle, and here, the content of the bottle 1 is about 280 ml. Moreover, the resin amount of the bottle 1 is 23.1 g.

The bottle 1 is molded by a stretch molding method such as biaxial stretch blow molding using, for example, a thermoplastic resin such as polyethylene, polypropylene, or polyethylene terephthalate as a main material.
An example of the manufacturing process of the bottle 1 will be described. First, a thermoplastic resin is injected into a mold, and a preform is injection molded. The preform is composed of a mouth portion having the same shape as the mouth portion 2 and a bottomed tubular portion connected to the lower side thereof. After injection molding, the preform is set on a blow molding machine and the tubular portion of the preform is heated. And while extending a cylindrical part to a vertical direction with an extending | stretching rod, compressed air is blown and a cylindrical part is extended to a horizontal direction. The stretched cylindrical portion is pressed against the inner surface of the mold and then solidified. Thereby, the shoulder part 3, the trunk | drum 4, and the bottom part 5 are shape | molded, and a series of shaping | molding of the bottle 1 is completed.

  The mouth part 2 is open at the upper end and functions as a beverage spout. The opening of the mouth 2 is opened and closed by a cap (not shown). The shoulder portion 3 has a circular cross section that gradually expands downward, and connects the lower end of the mouth portion 2 to the upper end of the trunk portion 4. The body part 4 is a part having a circular cross section of a side straight, and has a label attaching part 10, an upper maximum outer diameter part 12, a lower maximum outer diameter part 14, and a connection part 16. The label attaching part 10 is formed by slightly denting the middle part in the vertical direction of the body part 4 along the circumferential direction of the bottle, and a label for clearly showing the contents of the bottle 1 is attached thereto. The maximum outer diameter portions 12 and 14 are portions having the maximum diameter in the bottle 1 and have the same height as each other. The upper maximum outer diameter portion 12 connects the upper end of the label attaching portion 10 to the lower end of the shoulder portion 3. The lower maximum outer diameter portion 14 connects the lower end of the label attaching portion 10 to the upper end of the connecting portion 16. The connection part 16 is a part connected to the upper end of the bottom part 5, and a part of a later-described concave rib 30 is formed.

  Here, the connecting portion 16 can be formed with a diameter slightly smaller than the maximum outer diameter portion 14, but as in the present embodiment, the connecting portion 16 and the maximum outer diameter portion 14 are formed with the same diameter, You may connect both together. In this case, although the connection part 16 can be grasped as a part of the maximum outer diameter part 14, the part where the part of the concave rib 30 is formed is defined as the connection part 16 here.

  As shown in FIGS. 1 to 4, the bottom 5 has a so-called champagne base shape. Specifically, the bottom portion 5 includes a central recess portion 20, a ground contact portion 22, and a heel portion 24. The center recess 20 is a portion formed by recessing the center of the bottom 5 upward in a substantially hemispherical shape, and its center of curvature is located outside the bottle and on the center axis of the bottle 1. . The height position of the central portion of the central depression 20 is located above the upper end of the heel portion 24. The grounding part 22 is an annular part connected to the outer part of the central depression 20, and when the bottle 1 is self-supporting on the installation surface, the only part that the bottle 1 contacts is the grounding part 22. Here, the vertical cross section of the ground contact portion 22 is an arc having a center of curvature inside the bottle. The heel portion 24 extends so as to expand upward from the outer portion of the grounding portion 22, and connects the outer portion of the grounding portion 22 to the lower end of the connecting portion 16 in the bottle circumferential direction. The heel portion 24 is formed so as to gradually decrease in diameter from the lower end of the connection portion 16 to the lower side, and the shape thereof may be formed by an inclined surface (straight surface), a curved surface, or a combination thereof. it can.

  A plurality of concave ribs 30 are formed at equal intervals in the circumferential direction of the bottle, and reinforce the bottom 5 which is a champagne base. The concave rib 30 is formed so as to longitudinally cut the boundary 40 between the heel portion 24 and the connecting portion 16. Specifically, the concave rib 30 extends in the vertical direction such that its lower end 30a is at the lower portion of the heel portion 24, its upper end 30b is at the upper end of the connection portion 16, and its intermediate portion 30c is at the boundary 40. And is formed on the heel portion 24 and the connecting portion 16 (see: FIG. 2A). The concave rib 30 includes a rib bottom surface 32 and a pair of rib side surfaces 34 and 36 formed on one side and the other side of the rib bottom surface 30 in the bottle circumferential direction (see: FIG. 2 (b). )). The rib bottom surface 32 extends outward with a steep inclination from the heel portion 24 so as to chamfer the boundary 40 (see: FIGS. 3A and 3B). In other words, the rib bottom surface 32 does not extend along each surface constituting the heel portion 24 and the connection portion 16, but is formed in the heel portion 24 and the connection portion 16 so as to extend at an angle different from each surface. Has been. The rib bottom surface 32 is substantially rectangular when viewed from the front, and an upper end and a lower end (corresponding to the upper end 30 b and the lower end 30 a described above) are connected to the other surfaces of the connection portion 16 and the heel portion 24 without a step.

  According to the bottle 1 described above, since the bottom 5 has a so-called champagne base shape, the ratio of the bottom height L1 to the total bottle height L can be reduced as compared with the petaloid-shaped bottom structure (see: Figure 2). Thereby, in the small size bottle 1, since the straight length L2 of the trunk | drum 4 can be enlarged, the bendability of the bottle 1 can be ensured.

  In addition, since the plurality of concave ribs 30 are formed so as to cut the boundary 40 between the heel portion 24 of the bottom portion 5 and the lower portion of the body portion 4, internal pressure can be released in the extending direction of the concave ribs 30. . Thereby, while being able to suppress the elongation to the vertical direction of the bottle 1 (bottom part 5) by the gas pressure of carbonated beverages, generation | occurrence | production of a stress crack can be suppressed. In particular, since the rib bottom surface 32 of the concave rib 30 is extended so as to chamfer the boundary 40, the reinforcing effect by the concave rib 30 can be further enhanced.

  Moreover, since the length of the concave rib 30 is not formed so long as to cover the entire region of the bottom portion 5, it is advantageous in relation to stress cracks. That is, although the concave ribs originally suppress the occurrence of stress cracks, the concave ribs that are too long can cause stress cracks. In this respect, in the present embodiment, since the lower end 30a of the concave rib 30 does not reach the grounding portion 22 and the central recess portion 20, both the suppression of the occurrence of stress cracks and the suppression of bottle deformation are appropriately achieved. be able to.

  Therefore, according to the present embodiment, the strength of the bottle 1 can be ensured without increasing the thickness, so that it is possible to reduce the weight of the small-sized bottle 1 having the bendability suitable for filling the carbonated beverage. it can.

  The bottle 1 of the present embodiment is a pressure-resistant bottle that can be suitably used when the bottle internal pressure at the time of sealing is positive. However, the target of the beverage to be filled is not limited to carbonated beverages, but is a sparkling beverage. May be. Moreover, even if it is various non-carbonated drinks, such as green tea, oolong tea, black tea, coffee, fruit juice, before filling and sealing these, the bottle internal pressure after sealing by adding liquid nitrogen in the bottle 1 Can be made positive pressure. In short, the bottle 1 is configured so that it can be suitably filled with a beverage having an internal pressure in the range of 0 to 0.8 MPa, whether it is a carbonated beverage or a non-carbonated beverage.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate.

  For example, the number, length, width, depth, angle, and shape of the concave ribs 30 can be designed as appropriate. In the above embodiment, the length and depth of the eight concave ribs 30 are 16.75 mm and 2.06 mm, respectively, for a lower height of 17.25 mm (L-L2, see FIG. 2B). Is set. Further, the rib bottom surface 32 may be linear or a curved surface. The number of the concave ribs 30 is preferably 6 to 10 when the content of the bottle 1 is in the range of 200 to 300 ml. According to the knowledge of the present inventor, if the number is less than 6, the amount capable of absorbing the elongation in the vertical direction of the bottle 1 due to the internal pressure tends to be reduced, and if it exceeds 10, the stress cracks are likely to be adversely affected. It is.

  Moreover, the shape of the trunk | drum 4 is not specifically limited, It can design suitably. For example, the waist portion 4 can be formed with a constriction for improving ease of holding or a groove for improving strength.

  1: bottle, 4: trunk, 5: bottom, 16: connecting part (lower part of trunk), 20: central depression, 22: grounding part, 24: heel part, 30: concave rib, 30a: lower end, 30b : Upper end, 30c: middle part, 32: rib bottom, 40: boundary

Claims (5)

In a plastic bottle with a bottom that leads to the body,
The bottom is
A central recess formed by recessing the central portion of the bottom upward in a substantially hemispherical shape;
An annular grounding portion connected to an outer portion of the central depression,
An inclined or curved heel part that connects the outer part of the grounding part to the lower part of the body part in the bottle circumferential direction, and
A plastic bottle comprising a plurality of concave ribs formed in a longitudinal direction at a boundary between the heel portion and a lower portion of the body portion in the bottle circumferential direction.   The plastic bottle according to claim 1, wherein a rib bottom surface of each of the plurality of concave ribs extends to chamfer the boundary.   3. The plastic bottle according to claim 1, wherein lower ends of the plurality of concave ribs exist in the heel portion and do not reach the ground contact portion and the central recess portion.   The plastic bottle according to any one of claims 1 to 3, wherein the plurality of concave ribs are formed at equal intervals in the bottle circumferential direction. The content of the plastic bottle is in the range of 200 to 300 ml,
The plastic bottle according to claim 4, wherein the plurality of concave ribs is 6 to 10 in number.

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