Carbonated beverage bottle with improved petaloid base

Abstract

A bottle for holding a carbonated beverage, comprising: a body; and a base having a substantially hemispherical geometric base shape (S1) extending from a lower end of the body. The base has a petaloid foot structure, which is axially symmetric about a longitudinal axis (X) of the bottle, and is formed from a plurality of feet projecting downward from the geometric base shape (S1), with a plurality of valleys separating adjacent pairs of feet. Each valley has a base line (81) that substantially follows the geometric base shape (S1). The ratio of the maximum foot depth (F), which is the maximum vertical distance from the geometric base shape (S1) to the surface (S2) of the foot, to the seating radius, which is the radius of the largest circle formed by the contact points between the plurality of feet and a flat surface (9) when the bottle is placed upright on the flat surface, is 0.5±0.01.

Description

[Technical Field]

[0001] The present invention relates to the manufacture of freestanding blow-molded plastic bottles. In particular, the present invention relates to beverage containers for carbonated water and carbonated soft drinks. [Background technology]

[0002] Blow-molded plastic bottles are well known for supplying carbonated beverages to the consumer market. Such bottles offer several advantages over traditional glass bottles. These advantages include ease and safety of handling and manufacturing costs.

[0003] Blow molding of such containers typically involves inserting a preform, preheated above the glass transition temperature of the material, into a mold shaped like the container and injecting a fluid (particularly a gas such as air, but also an incompressible fluid such as water) under pressure into the preform. A stretch rod may be used to stretch the preform along the axis of the mold before and during blowing.

[0004] Such containers include a neck portion reinforced to receive, for example, a screw cap, a body extending from the neck portion, and a base portion joined to the body. The base portion is shaped to allow the container to stand upright when placed on a flat surface. Typically, the bottle base includes a plurality of feet symmetrically arranged about the axis of the bottle. Such bases are described as "petaloid" because they resemble the petals of a flower. More specifically, petaloid in the context of bottle base design refers to a radial foot structure having a cross-sectional shape resembling the petals of a flower in a transverse plane.

[0005] Known bottle sizes include the 0.5 liter type bottle, which is a bottle type sized to hold 0.5 liters of carbonated beverage, and the 1.5 liter type bottle, which is a bottle type sized to hold 1.5 liters of carbonated beverage. Other bottle sizes are known in the industry.

[0006] The design challenge is to create a strong, durable base. The requirements for such containers are codified in various industry-accepted standards, such as the International Society of Beverage Technologists' "Voluntary Standard Test Methods for PET Bottles 10 / 2003 Revision 1." Importantly, certain mechanical features are required to be satisfactory for the bottled carbonated beverage industry. The bottle must be designed to mechanically withstand an internal pressure of 10 bar. Furthermore, the bottle must be able to withstand a 180 cm drop onto a steel surface. Resistance to stress cracking during a 10-minute immersion in a 0.200% solution of sodium hydroxide pressurized to 5.3 bar, as well as temperature cycling within the range typically encountered during operation, are also required. Typically, such tests are performed in batches of 12 or more bottles.

[0007] To blow a plastic bottle with a given base design, a certain blowing pressure is required to blow the preform in an appropriately shaped mold. The higher the pressure required, the higher the cost, both in terms of energy and the robustness of the molding machinery. To blow a PET bottle, a blowing pressure of the order of 30 bar is generally required. Currently, the lowest possible limit is believed to be 20 bar. It would be desirable to reduce this pressure further. For example, a blowing pressure of less than 16 bar would be highly desirable.

[0008] The object of the present invention is therefore to propose a bottle base design which achieves the necessary mechanical features mentioned above while minimizing the required blowing pressure. This result is achieved by the claimed invention. Summary of the Invention

[0009] The present invention relates to a bottle for holding carbonated beverages, the bottle comprising a body and a base extending from a lower end of the body. The base has a substantially hemispherical geometric base shape and a plurality of feet projecting downwardly from the geometric base shape. A plurality of valleys separate adjacent pairs of feet, each valley having a base line substantially aligned with the geometric base shape. The plurality of feet and the plurality of valleys together form a petaloid foot structure having axial symmetry about the longitudinal axis of the bottle.

[0010] The bottle base is described in terms of a maximum foot depth, which is the maximum vertical distance from the geometric base to the surface of the foot, and a seating radius, which is the radius of the largest circle formed by the contact points of the feet with a flat surface when the bottle is placed upright on the flat surface.

[0011] For a bottle base having a maximum foot depth to seating radius ratio of 0.5±0.01, the bottle so produced will meet the mechanical characteristics necessary for dispensing carbonated soft drinks and will require a blowing pressure of less than 16 bar during manufacture. Preferably, the minimum radius of curvature of any part of the base is 6.5 mm. More preferably, the minimum radius of curvature of any part of the base is 7 mm.

[0012] Particular configurations having a maximum foot depth to seating radius ratio of 0.51 and an angle between pairs of opposing valley slopes of adjacent foot pairs of 37 degrees, a maximum foot depth to seating radius ratio of 0.49 and an angle between pairs of opposing valley slopes of adjacent foot pairs of 44 degrees, a maximum foot depth to seating radius ratio of 0.50 and an angle between pairs of opposing valley slopes of adjacent foot pairs of 44 degrees, and a maximum foot depth to seating radius ratio of 0.51 and an angle between pairs of opposing valley slopes of adjacent foot pairs of 41 degrees are also highly beneficial.

[0013] The bottle may include, but is not limited to, five feet.

[0014] The bottle can be a 0.5 L type bottle or a 1.5 L bottle. The bottle can also be any other standard type bottle, such as a 0.2 L type bottle, a 0.33 L bottle, a 1 L bottle, and a 2 L bottle. Bottles with other capacities can also be made in accordance with the present invention.

[0015] The bottles can be made from PET, PEF, or other plastics can be used instead.

[0016] The present invention also provides a method for manufacturing a bottle for holding a carbonated beverage, comprising the steps of: providing an openable blow mold cavity defining a bottle shape as described above; providing a hollow preform; adjusting the temperature of the preform; Inserting the preform into a blow mold cavity; injecting a pressurized fluid at a pressure of less than 16 bar into the preform so that the preform is stretched outwardly into contact with the surfaces of the blow mold cavity and assumes the shape of a bottle defined by the blow mold cavity; and c. opening the blow mold cavity and removing the bottle formed in the cavity.

[0017] Due to the above-described bottle configuration, the blowing pressure is substantially reduced compared to known methods of blow molding bottles.

[0018] Other features and advantages of the present invention will become apparent from the following description. [Brief explanation of the drawings]

[0019] The accompanying drawings are given as non-limiting examples. [Figure 1] 1 is a general view of a plastic bottle. [Figure 2] FIG. 1 is a diagram of the base of the bottle showing the hemispherical geometry. [Figure 3] FIG. 1 is a view of the base of a bottle showing the petaloid formation of multiple feet and multiple valleys. [Figure 4] FIG. 10 is a diagram showing the seating radius of the bottle base portion. [Figure 5] FIG. 5 is an alternative view of the base portion shown in FIG. [Figure 6] 10A and 10B are diagrams showing angles between adjacent legs of a bottle base; DETAILED DESCRIPTION OF THE INVENTION

[0020] The terms "upper" and "lower" refer to a coordinate system in which the bottle is standing on a surface with its neck at the top and its base at the bottom. The term "axial" refers to a major axis X that runs through the neck of the bottle and the center of its base.

[0021] It should be understood that standard rounding up rules apply throughout, so an angle stated as 41 degrees means a range of 40.5 to 41.4 degrees.

[0022] FIG. 1 shows a general view of a bottle 1 made by stretch blow molding of a preform made of a thermoplastic material, for example PET (polyethylene terephthalate) or PEF (polyethylene furanoate).

[0023] At its upper end, the bottle 1 comprises a neck 2 reinforced to support a closure lid (not shown), the neck 2 being provided with a mouth 3 through which the contents of the bottle can be poured or extracted, for example using a drinking straw. In the extension of the neck 2, the container 1 comprises, at its upper part, a shoulder 4 which extends in the opposite direction to the neck 2 and which is extended by a side wall or body 5 which, in the embodiment shown, has a substantially cylindrical shape and is circumferentially oriented about the main axis X of the container 1. The body 5 terminates at its lower end in a base 6.

[0024] The base 6 is shown in more detail in Figures 2 and 3. The geometric base shape or form of the base 6 approximates a hemispherical surface S1. Arranged symmetrically about axis X and extending downwardly from the geometric base shape S1 are a plurality of feet 7. The plurality of feet functions to hold the bottle upright on a surface. In some configurations, the plurality of feet consists of five feet. In other configurations, the plurality of feet can be three, four, six, seven, or more feet. Five feet is commonly used because it provides a good compromise between stability and manufacturing costs.

[0025] As shown in Figure 3, a valley 8 is located between each pair of adjacent feet. As shown in Figures 2 and 3, the base line 81 of each of these valleys 8 coincides with the geometric base shape S1. Thus, the hemispherical surface S1 results from the rotation of the base line 81 of the valley 8 formed by two adjacent feet 7 around the central axis of the bottle, as exemplarily shown in Figure 2. The feet 7 and valleys 8 together form a petaloid base structure on which the bottle can stand upright. The term petaloid should be understood as given in the introduction above.

[0026] Next, we define the parameters necessary to describe the optimized base of the present invention.

[0027] Maximum Foot Depth As shown in Figure 2, the congruent surface S2 is a surface that forms each foot 7. Also shown in Figure 2, the maximum foot depth F represents the magnitude of the longest possible normal vector on the hemisphere S1 to a point on the surface S2. In other words, the maximum foot depth F is the maximum distance from the hemisphere S1 to the congruent surface S2, measured in a direction perpendicular to the hemisphere S1. As will be appreciated, the maximum foot depth F depends on the size and shape of each foot 7.

[0028] Seating Radius 4 and 5. When the bottle is placed upright on a flat surface 9, each foot 7 contacts the surface 8 at a foot-to-surface contact area 101. The contact area may or may not be continuous. Within the contact area, there are contact points closer to the axis X and contact points further from the axis X. The seating radius S is defined as the radius of the (largest) circle formed by the foot-to-surface contact points 10 (outermost from the axis) as shown. The seating radius is important for the stability of the bottle when seated on a flat surface.

[0029] Minimum Transition Radius For example, as can be seen in Figure 3, the base 6 does not exhibit sharp edges, and the edges of each foot are rounded. The smallest radius within the geometry of each foot 7 is called the minimum transition radius R. The minimum transition radius R indicates the radius of the edge rounding that is the transition area between the foot 7 and the rest of the base and / or bottle geometry. That is, a bottle described as having a minimum radius of curvature of 7 mm anywhere in the base means that there are no radii sharper than 7 mm locally within the base.

[0030] The angle between adjacent valley slopes As shown in Figure 6, opposite sides or slopes 11a, 11b of adjacent feet 7 face each other across an intervening valley 8. The angle α between each pair of opposing valley slopes 11a, 11b is a measure of the steepness of the valley. In mathematical terms, the angle between opposing slopes 11a, 11b is defined as the angle between the normal vectors to each pair of opposing slopes.

[0031] Base optimization With the above objectives in mind, the inventors have experimented with numerous base designs. Each design considered was tested to determine whether the bottle was sufficiently mechanically robust for use in containing carbonated soft drinks. Specifically, the tests detailed in the introduction above were conducted. The tests included resistance to the appropriate internal pressures typically associated with carbonated soft drinks, resistance to a 180 cm drop onto a steel plate, resistance to a stress cracking condition consisting of placing a pressurized bottle solution of sodium hydroxide, and resistance to temperature cycling.

[0032] Table 1 shows the results of tests performed on each of the 13 sample bottle designs. All bottles tested were made from PET. For each stage of testing, more than 11 bottles per design were tested. For drop tests, 25 bottles per design were tested.

[0033] The furthest to the right indicates whether the bottle met the mechanical criteria above. If the bottle maintained its integrity throughout each test, the word "Pass" is indicated. If the bottle failed during testing, the word "Fail" is indicated.

[0034] The second column from the right shows the blow pressure required during the manufacture of each specific bottle. Also shown are parameters for maximum foot depth to seating radius ratio, minimum transition radius, and angle between valley slopes for each test bottle.

[0035] [Table 1]

[0036] Bottle 1 is an example of a commercially available prior art bottle. This bottle met mechanical performance standards but required a blowing pressure of 22 bar during manufacture. Similarly, Bottle 2 was able to withstand the mechanical testing conditions but required a costly blowing pressure of 22 bar during manufacture.

[0037] For bottles having a base with a minimum radius of curvature of 7mm between any part of the base, specifically the foot 7 and any other part of the bottle geometry, the inventors have identified a bottle base design with the following combination of features that achieves the desired mechanical properties while requiring a blowing pressure of 16 bar or less:

[0038] Most essentially, the inventors have determined that this result is achieved when the ratio of maximum foot depth to seating radius is 0.5±0.01.

[0039] By limiting the design to these parameter ranges, the objectives of the present invention are achieved. For example, Bottle 3, Bottle 5, Bottle 10, and Bottle 13 in Table 1 are bottles according to the present invention. These bottles passed the mechanical testing requirements and therefore provided the best results. Bottle Configurations 3, 10, and 13 required a blowing pressure of 16 bar during manufacture, while Bottle 5 was manufactured using a blowing pressure of 14 bar. This pressure is significantly lower than previously known pressures.

[0040] Bottle manufacturing A mold is provided having a cavity shaped to form the bottle described above. A temperature-conditioned hollow preform is inserted into the mold. In some configurations, a stretch rod is used to stretch the preform along the longitudinal axis of the bottle. An extensible stretch rod is pushed downward along the longitudinal axis to longitudinally stretch the preform until the bottom of the preform is adjacent to the bottom of the cavity.

[0041] A fluid, typically a gas, is blown into the hollow preform, forcing it to assume the shape of the mold. The introduction of the fluid may begin before the stretch rod completes the longitudinal stretching of the preform. Due to the configuration of the bottle according to the present invention, having a base portion as described above, the pressure required to blow-mold such a bottle is less than 16 bar. After cooling, the mold is removed from the bottle.

Claims

1. A bottle (1) for holding a carbonated beverage, A main body (5), a base portion (6) extending from the lower end of said body (5) and having a substantially hemispherical geometric base shape (S1), a plurality of feet (7) projecting downward from the geometric base shape (S1); a plurality of valleys (8) separating pairs of adjacent feet (7), each valley (8) having a base line (81) that substantially follows the geometric base shape (S1); a base portion (6), wherein the plurality of feet and the plurality of valleys together form a petaloid foot structure having axial symmetry about a longitudinal axis (X) of the bottle; a maximum foot depth (F) which is the maximum vertical distance from the geometric base shape (S1) to the foot surface (S2); a seating radius (S) that is the radius of the largest circle formed by contact points (10) between the plurality of feet and a flat surface (9) when the bottle is placed upright on the flat surface, A bottle (1) characterized in that the ratio of said maximum foot depth to said seating radius is 0.5±0.

01.

2. 2. The bottle according to claim 1, wherein the minimum radius of curvature of any part of the base (6) is 6.5 mm.

3. 2. The bottle according to claim 1, wherein the minimum radius of curvature of any part of the base (6) is 7 mm.

4. 4. The bottle of claim 3, wherein the ratio of the maximum foot depth to the seating radius is 0.51 and the angle between the pair of opposing valley slopes (11a, 11b) of the pair of adjacent feet (7) is 37 degrees.

5. 4. The bottle of claim 3, wherein the ratio of the maximum foot depth to the seating radius is 0.49 and the angle between the pair of opposing valley slopes (11a, 11b) of the pair of adjacent feet (7) is 44 degrees.

6. 4. The bottle of claim 3, wherein the ratio of the maximum foot depth to the seating radius is 0.51 and the angle between the pair of opposing valley slopes (11a, 11b) of the pair of adjacent feet (7) is 41 degrees.

7. 4. The bottle of claim 3, wherein the ratio of the maximum foot depth to the seating radius is 0.50 and the angle between the pair of opposing valley slopes (11a, 11b) of the pair of adjacent feet (7) is 44 degrees.

8. A bottle according to any one of claims 1 to 7, wherein said plurality of feet (7) is five feet.

9. The bottle according to any one of claims 1 to 8, wherein the bottle is a 0.5 liter type bottle.

10. The bottle according to any one of claims 1 to 8, wherein the bottle is a 1.5 liter type bottle.

11. The bottle of any one of claims 1 to 10, wherein the bottle is formed from PET.

12. The bottle of any one of claims 1 to 10, wherein the bottle is formed from PEF.

13. 1. A method for manufacturing a bottle for holding a carbonated beverage, comprising: Providing an openable blow mould cavity defining the shape of the bottle according to any one of claims 1 to 12; providing a hollow preform; adjusting the temperature of the preform; inserting the preform into the blow mold cavity; injecting a pressurized fluid at a pressure of less than 16 bar into the preform so that the preform stretches outwardly and contacts the surfaces of the blow mould cavity and assumes the shape of the bottle defined by the blow mould cavity; opening the blow mold cavity and removing the bottle formed in the cavity; A method comprising:

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