EP2289809B1

EP2289809B1 - Base for pressurized bottles

Info

Publication number: EP2289809B1
Application number: EP10075356A
Authority: EP
Inventors: Anthony J. Scott; John R. Ross
Original assignee: Amcor Rigid Plastics USA LLC
Current assignee: Amcor Rigid Packaging USA LLC
Priority date: 2009-09-01
Filing date: 2010-08-19
Publication date: 2012-04-04
Anticipated expiration: 2030-08-19
Also published as: ATE552177T1; US20110049083A1; EP2289809A1

Abstract

A plastic bottle (10) with a base (14) centered on a vertical axis (Y), a continuous standing ring (16) to support the bottle, a side wall (18) formed unitarily with the base extending from the base upward to an upper side wall end (20), and a neck (22) connected to the side wall upper end, the neck including a finish (24) adapted to receive a cap to close an opening (26) into the bottle interior. The bottle base standing ring is defined in vertical cross-section by a continuous curve bounded on a radial inside by an interior region (32) that can include a plurality of concave domed wedge-shaped sections (34) interspaced with buttress sections (36) having substantially planar inclined outer portions (38). The bottle base standing ring has a diameter (D) less than 80% of the maximum side wall width (W) and is bounded on a radial outside by a conic section portion (46) centered on the vertical axis having an apex angle of less than 160° to improve the perpendicularity of the bottle.

Description

BACKGROUND

The present disclosure is directed to plastic bottles, and particularly to a supporting champagne style base that is unitary with the remainder of the bottle, which improves the perpendicularity of the bottle.
Plastic bottles that include a base having a continuous uninterrupted standing ring for supporting the bottle on any underlying surface are sometimes referred to having a champagne style base. The perpendicularity or vertical alignment of such bottles can depend on the evenness of material distribution in the area of the standing ring, particularly when the bottles are subjected to even small internal pressures of 103.45 kP (15 psi; 775 torr) or less. While small variations from a true vertical alignment can be tolerated, any significant variation may cause problems in subsequent labeling and boxing of such bottles. While a large diameter standing ring is generally thought to provide enhanced stability as a result of the larger foot print, the large diameter standing ring is more flexible as a result of less material being present in the standing ring. As a result, even small variations in material distribution in large diameter standing rings can lead to unacceptable variations in the vertical alignment or perpendicularity of the bottle. This problem has in the past been addressed by forming a preform with significant non-uniform wall thicknesses so that a substantial amount of material is placed in the chime in direct alignment with the standing ring. Examples are to be found in US Patents 4,725,464 ; 4,780,257 ; 4,889,752 and 6,248,413 .
US Published Application 2004/0251258 discloses in Figs 22 and 23 a blow-molded thin wall plastic container "Ae" having a circular cross section with a neck 80, a shoulder 81, a body 82 and a bottom 83. The bottom 83 includes a peripheral wall 88 and a bottom wall 89, of which the peripheral wall 88 is inclined by a predetermined angle and has its lower end 88a linked to grounding bottom edge wall 89a of the bottom wall 89 having an upwardly curved surface 89 at the center thereof. The outer periphery of the grounding bottom edge wall 89a of the bottom wall 89 has a diameter remarkably smaller than that of the peripheral wall 85 of the body. The lower end 88a of the peripheral wall 88 is so inclined as to be connected to the outer periphery of the grounding bottom edge wall 89a of the bottom wall 89. The bottom 83 is distinguished by a transversal rib 91 arranged under the peripheral wall 88 of the bottom to surround the entire periphery of the container. Both the zone connecting the upper wall section 91a and the lower wall section 91 b of the transversal rib 91 and the zone connecting the upper wall section 91 a and the lower wall section 91 b show an arcuate profile. The lower walls section 91 b of the transversal rib 91 and the peripheral wall 88 of the bottom define a predetermined angle. In connection with the angle of inclination of the peripheral wall 88, the lower wall section 91 b of the transversal rib 91 is substantially vertical while the upper wall section 91 a is slightly inclined. The wall thickness t1 of the lower end 88a of the peripheral wall 88 of the bottom is greater than the wall thickness t2 of the peripheral wall 85 of the body because the lower end 88a has a diameter and a blow ratio smaller than those of the peripheral wall 88. Additionally, the lower wall section 91 b of the transversal rib 91 is substantially vertical while the wall thickness of the transversal rib 91 is increased at and near the grounding bottom edge wall 89a of the bottom wall 89.
Japan Published Application JP 55 163 137 A discloses a bottle provided with a bottom structure similar to that of a champagne bottom in which the free standing properties of the bottle are secured by an annular portion 1 in contact with the ground and formed at the lower end of an outer peripheral wall portion 2. A bottom wall portion is shown in Figs 1, 2, 4A and 4C as being inwardly inclined, and an inner peripheral wall portion in the form of a truncated cone is shown in Figs 2, 4A and 4B. The pressure resisting properties of the bottom are said to be secured by the truncated cone inner peripheral wall portion and a central portion of the bottom wall having a convex curved surface continuously formed thereabove. The annular portion in contact with the ground has a small radius of curvature as shown in Figs 2 and 4A that can often exhibit insufficient biaxial orientation during molding. Thus, the annular portion in contact with the ground is further expanded in Fig 4C into a semi-circular shape in cross-section to provide a larger radius of curvature. However, when the radius of curvature increases, the pressure resisting strength of the entire base decreases so that the central portion of the bottom is easily deformed due to the internal pressure from carbonated beverages, or the like.
A significant disadvantage of using preforms having significant non-uniform wall thicknesses to place additional material in the chime in direct alignment with the standing ring is the additional polymer itself, which increases the cost of the bottle. There is thus a need for a lower-cost solution to enhance the perpendicularity or vertical alignment of blow molded plastic bottles having a champagne style base.
The problem of the prior art is solved by the features of the independent claims 1 and 2.

SUMMARY

A plastic bottle has a base centered on a vertical axis. The base has a continuous standing ring to support the bottle on any underlying support surface. A side wall is formed unitarily with the base and extends from the base upward to an upper end of the side wall. A neck is unitarily connected to the upper end of the side wall that includes a finish adapted to receive a cap to close an opening into the bottle interior. The bottle has a height defined by the distance between the opening and the standing ring, and a maximum width across the bottle. To enhance the vertical alignment or perpendicularity of the bottle, the base standing ring is defined in vertical cross-section by a continuous curve. The base standing ring has a diameter less than 80% of the maximum side wall width. The continuous curve of the base standing ring is bounded on a radial outside by a conic section portion centered on the vertical axis. The vertical alignment or perpendicularity of the bottle can be further enhanced by limiting the average standing ring thickness to between 1.0 and 1.3 times the thickness of the side wall, (claim 1), or the continuous curve of the base standing ring is bounded on a radial inside by an interior region that includes a plurality of concave domed wedge-shaped sections interspaced with buttress sections having substantially planar inclined outer portions, wherein the buttress sections have inclined outer portions that are inclined at an angle of between 8° and 16° with respect to a plane defined by the base standing ring (claim 2).
The vertical alignment or perpendicularity of the bottle can be enhanced by limiting the apex angle of the conic section portion to less than 160°. The vertical alignment or perpendicularity of the bottle can be further enhanced by maintaining the width of the conic section portion to at least 0.889 cm (0.035 inches).
The vertical alignment or perpendicularity of the bottle can also be enhanced by limiting the standing ring diameter to be more than 70% of the maximum bottle side wall width. The vertical alignment or perpendicularity of the bottle can be further enhanced by limiting variation in the standing ring thickness to less than ± 20%. Another feature of the base that can improve the vertical alignment or perpendicularity of the bottle is confining the vertical cross-sectional radius defining the standing ring to between 0.254 cm and 0.762 cm (0.100 inches and 0.300 inches).
Another feature of the base that can improve the vertical alignment or perpendicularity of the bottle is limiting the curvature of the concave dome portion to a radius of at least 1.0 times the standing ring diameter. The vertical alignment or perpendicularity of the bottle can be further enhanced by providing the angle of tangency at the point of intersection of the concave dome portion and the standing ring vertical cross-section to be at least 45°.
Other features of the present bottle base and the corresponding advantages of those features will become apparent from the following discussion of the preferred embodiments of the present container, exemplifying the best mode of practice, which is illustrated in the accompanying drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the features. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.

Brief Description of the Drawings

Fig 1 is a sectional outline of an exterior surface of a bottle.
Fig 2 is a bottom plan view of the base of the bottle in Fig 1.
Fig 3 is a sectional outline view of the base taken along line 3 - 3 of Fig 2.
Fig 4 is an enlarged view of a portion of the left side of Fig 3.
Fig 5 is an enlarged view of a portion of the right side of Fig 3.

Description of a Preferred Embodiment

A bottle 10 is shown in Fig 1 and the other Figs that has a generally cylindrical body 12 surrounding a longitudinal axis Y and a closed base 1 that is unitary with the remainder of the bottle. The 14 base has a continuous standing ring 16 to support the bottle 10 on any underlying support surface. The standing ring 16 has a standing ring diameter D. A side wall 18 is formed unitarily with the base 14 and extends from the base upward to an upper end 20 of the side wall 18. A neck 22 is unitarily connected to the upper end 20 of the side wall 18 by a shoulder portion 21. The neck 22 includes a finish 24 adapted to receive a cap (not shown) to close an opening 26 into the bottle interior 28. The bottle 10 has a height H defined by the distance between the opening 26 and the standing ring 16, and a maximum width W across the bottle 10.
To enhance the vertical alignment or perpendicularity of the bottle 10, the base standing ring 16 is defined in vertical cross-section by a continuous curve of radius R_s, shown in Figs 4 and 5, which can be between 0.254 cm and 0.762 cm (0.100 inches and 0.300 inches). The radius R_S is independent of the standing ring diameter D, where the standing ring diameter D is measured at the lowest point on the standing ring 16. The curve defining the standing ring 16, being continuous, does not include any flattened portion in the plane X defined by the standing ring, shown in Fig 3. The base standing ring 16 has a diameter D less than 80% of the maximum side wall width W. The base standing ring 16 can have a diameter D greater than 70% of the maximum side wall width W.
The continuous curve of the base standing ring 16 defined by R_S is bounded on a radial inside, starting about at point or ring 30, by an interior region 32. The interior region 32 can include a plurality of concave domed wedge-shaped sections 34 as seen in Fig 2. The concave domed wedge-shaped sections 34 can be formed by a constant inside radius R_C of at least 1.0 times the standing ring diameter D as shown in Figs 3 and 5. The angle of tangency at the point of intersection 30 of the concave dome portions 34 and the curve defining the standing ring 16 measured from the plane X as shown in Fig 5 can be between 45° and 55°. The wedge-shaped sections 34 can be interspaced with buttress sections 36, which can also be wedge-shaped. The buttress sections 36 can have substantially planar inclined outer portions 38. The planar outer portions 38 can be inclined at an angle θ of between 8° and 16° with respect to a plane X defined by the base standing ring 16 as seen in Fig 4. The buttress sections 36 can include inner portions 40 defined by a concave surface 42 that becomes circumferentially continuous as it approaches a central downwardly protruding portion 44 surrounding the axis Y of the bottle. The lowest surface of the downwardly protruding section 44 can be spaced above the plane X by a distance H_C of 14% to 20% of the standing ring diameter D.
The continuous curve of the base standing ring 16 defined by radius R_S is bounded on a radial outside by a conic section portion 46 starting at point or ring 48 and extending linearly upwardly and outwardly to point or ring 50 as shown in Figs 4 and 5. The distance between point or ring 48 and point or ring 50 defines the width of the conic section portion 46, which is preferably at least 0.089 cm (0.035 inches). The conic section portion 46 is seen to be generated by the rotation around the vertical axis Y of a line generating a conic section having an included apex angle Φ of less than 160° as shown in Fig 3. A base outer portion 52 extending outward from point 50 to the side wall 18 can be formed as a torus segment defined by a constant radius R_T of between about 12% and 20% of the standing ring diameter D.
Between the point or 30 and the point or ring 48, the material forming the standing ring 16 preferably has an average thickness of between 1.0 and 1.3 times the thickness of the material forming the side wall 18. Between the point or ring 30 and the point or ring 48, the thickness of the material forming the standing ring 16 desirably has a variation that is as small as possible and less than ± 20%.
By way of example, a bottle 10 as shown in Fig 1 can have a height H of 22.39 cm (8.813 inches) and a maximum width W of 6.40 cm (2.52 inches). The standing ring diameter D of the example bottle can be 4.826 cm (1.90 inches). The vertical cross-section radius R_S defining the exterior surface of the standing ring 16 of the example bottle can be 0.381 cm (0.150 inches. The width of the conic section portion 46 of the example bottle can be 0.163 cm (0.064 inches). The average thickness of the material forming the side wall 16 of the example bottle can be 0.0356 cm (0.014 inches) while the average thickness of the material forming the standing ring can be 0.0406 cm (0.016 inches). The inside radius R_C forming the concave surfaces of the domed wedge-shaped sections 34 of the example bottle can be 5.055 cm (1.990 inches). The angle of tangency at the point of intersection 30 of the concave dome portions 34 and the curve defining the standing ring 16 measured from the plane X in the example bottle can be 50°. The angle of inclination θ of the planar outer portions 38 of the buttress sections 36 of the example bottle can be 11°. The radius R_C defining the concave surface 40 of the example bottle can be 0.668 cm (0.263 inches). The lowest surface of the central downwardly protruding portion 44 of the example bottle can be spaced above the plane X by a distance of 0.800 cm (0.315 inches). The apex angle Φ of the conic section generating the portion 46 of the example bottle can be 150°. The radius R_T forming the base outer portion 52 of the example bottle can be 0.762 cm (0.300 inches). The example bottle showed a 36% improvement in perpendicularity over a prior design.

Claims

A plastic bottle (10) including a base (14) centered on a vertical axis (Y), the base having a standing ring (16) to support the bottle on any underlying support surface, a side wall (18) formed unitarily with the base and extending from the base upward to an upper end (20) of the side wall, and a neck (22) connected to the upper end of the side wall, the neck including a finish (24) adapted to receive a cap to close an opening (26) into the bottle interior, the bottle having a height (H) defined by the distance between the opening and the standing ring, and a maximum width (W) across the side wall, the base standing ring being defined in vertical cross-section by a continuous curve bounded on a radial inside by an interior region (32), the continuous curve being bounded on a radial outside by a conic section portion (46) centered on the vertical axis, the base standing ring having a diameter (D) less than 80% of the maximum side wall width and characterized by the standing ring (16) having an average thickness that is between 1.0 and 1.3 times the average thickness of the side wall (18).
A plastic bottle (10) including a base (14) centered on a vertical axis (Y), the base having a standing ring (16) to support the bottle on any underlying support surface, a side wall (18) formed unitarily with the base and extending from the base upward to an upper end (20) of the side wall, and a neck (22) connected to the upper end of the side wall, the neck including a finish (24) adapted to receive a cap to close an opening (26) into the bottle interior, the bottle having a height (H) defined by the distance between the opening and the standing ring, and a maximum width (W) across the side wall, the base standing ring being defined in vertical cross-section by a continuous curve bounded on a radial inside by an interior region (32), the interior region comprises a concave domed shaped portion, the continuous curve being bounded on a radial outside by a conic section portion (46) centered on the vertical axis, the base standing ring having a diameter (D) less than 80% of the maximum side wall width and characterized by the concave domed shaped portion having a plurality of concave domed wedge-shaped sections (34) interspaced with buttress sections (36) and the buttress sections having substantially planar inclined outer portions (38) inclined at an angle (θ) of between 8° and 16° with respect to a plane (X) defined by the base standing ring.
The plastic bottle of claim 1 or 2, wherein the base standing ring diameter (D) is more than 70% of the maximum side wall width (W).
The plastic bottle of either of claims 2 or 3, wherein the standing ring (16) has an average thickness that is between 1.0 and 1.3 times the average thickness of the side wall (18).
The plastic bottle of any of claims 1 - 4, wherein the variation in thickness around the circumference of the standing ring (16) is less than ± 20%.
The plastic bottle of any of claims 1 - 5, wherein the continuous curve of the standing ring has a defining radius (R_S) in vertical cross-section of between 2.54 mm (0.100 inches) and 7.62 mm (0.300 inches).
The plastic bottle of any of claims 2 - 6, wherein the concave domed wedge-shaped sections (34) are defined by a curve (R_C) having a radius of at least 1.0 times the standing ring diameter (D).
The plastic bottle of any of claims 1 - 7, wherein the conic section portion (46) outside the base standing ring (16) has a width of between 0.889 mm (0.035 inches) and 2.413 mm (0.095 inches).
The plastic bottle of any of claims 1 - 8, wherein the conic section portion (46) has an apex angle (Φ) of less than 160°.