Carbonated beverage bottle with improved petal-shaped bottom

Abstract

A bottle for containing a carbonated beverage, the bottle comprising a body and a bottom having a substantially hemispherical bottom geometry (S1) extending from a lower end of the body. The bottom comprises a petaloid foot formation which is axisymmetric about the longitudinal axis (X) of the bottle and is formed by a plurality of feet protruding downward from the bottom geometry (S1), the recesses of which separate adjacent pairs of feet. The bottom line (81) of each recess substantially coincides with the underlying geometry (S1). The ratio of the maximum foot depth (F), which is the maximum vertical distance from the underlying geometry (S1) to the foot surface (S2), to the base radius, which is the radius of the maximum circle formed by the points in contact with the foot and the flat surface (9) when the bottle stands vertically on the flat surface, is 0.5 + / -0.01.

Description

Technical Field

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

[0002] Blow molded plastic bottles are well known for supplying carbonated beverages to the consumer market. Such bottles have many advantages over conventional glass bottles. These advantages include ease of handling, safety, and low manufacturing costs.

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

[0004] Such containers include a reinforced neck for receiving, for example, a screw cap, a body extending from the neck, and a bottom connected to the body. The bottom is shaped so that the container can be placed upright on a flat surface. Typically, the bottom includes a plurality of feet symmetrically arranged around the axis of the bottle. Such a bottom is described as "petal-shaped" because it resembles the petals of a flower. More specifically, in the context of bottle bottom design, petal-shaped refers to a radial configuration of the feet that has a cross-sectional shape in a transverse plane similar to the petals of a flower.

[0005] Known bottle sizes include 0.5 liter bottles and 1.5 liter bottles, the 0.5 liter bottle being sized to hold 0.5 liters of carbonated beverage and the 1.5 liter bottle being sized to hold 1.5 liters of carbonated beverage. Other bottle sizes are also known in the art.

[0006] One of the design challenges is creating a base that is both strong and durable. The requirements for such containers have been codified in standards accepted by various industries, such as the International Beverage Technology Association's "Voluntary Standard Test Method for PET Bottles 10 / 2003 Revision 1". Importantly, certain mechanical properties must be present in order to meet the requirements of the bottled carbonated beverage industry. The bottles must be designed to have mechanical resistance to an internal pressure of 10 bar. In addition, the bottles must also be able to withstand being dropped from 180 cm onto a steel surface. The bottles are also required to have resistance to stress cracking for 10 minutes, based on a protocol where the bottles pressurized to 5.3 bar are immersed in a 0.200% sodium hydroxide solution, as well as resistance to temperature cycling in the range typically encountered during use. Typically, such tests are performed on batches of 12 bottles or more.

[0007] To blow-mold a plastic bottle with a given bottom design, a certain blowing pressure is required to blow the preform into a mold of the appropriate shape. The higher the required pressure, the higher the cost in terms of energy and durability of the molding machinery. Blow-molding PET bottles usually requires a blowing pressure of about 30 bar. 20 bar is currently considered to be a relatively low pressure that can be achieved. It is hoped that this pressure can be further reduced. For example, a blowing pressure below 16 bar is considered to be very ideal.

[0008] The object of the present invention is therefore to propose a bottle base design which minimizes the required blowing pressure while achieving the above-mentioned necessary mechanical properties. This result is achieved by the invention protected by the claims. Summary of the invention

[0009] The present invention relates to a bottle for containing carbonated beverages, the bottle comprising a main body and a bottom extending from the lower end of the main body. The bottom has a substantially hemispherical bottom geometry and comprises a plurality of legs protruding downward from the bottom geometry. Concave portions separate adjacent pairs of legs, and the bottom line of each concave portion is substantially consistent with the bottom geometry. The legs and the concave portions together form a petal-shaped leg formation having axial symmetry around the longitudinal axis of the bottle.

[0010] The base of the bottle is described by the maximum foot depth, which is the maximum vertical distance from the underlying geometry to the foot surface, and the base radius, which is the radius of the largest circle formed by the points of contact of the foot and the flat surface when the bottle stands vertically on the flat surface.

[0011] For a bottle base with a ratio of maximum foot depth to base radius of 0.5 ± 0.01, the bottle produced in this way not only meets the mechanical properties required for serving carbonated soft drinks, but also requires a blow molding pressure of less than 16 bar during the manufacturing process. Preferably, the minimum radius of curvature of any part of the bottom is 6.5 mm. More preferably, the minimum radius of curvature of any part of the bottom is 7 mm.

[0012] The specific arrangement has a maximum foot depth to base radius ratio of 0.51; and an angle of 37 degrees between pairs of relative recessed flanks of adjacent pairs of feet; a maximum foot depth to base radius ratio of 0.49; and an angle of 44 degrees between pairs of relative recessed flanks of adjacent pairs of feet; a maximum foot depth to base radius ratio of 0.50; and an angle of 44 degrees between pairs of relative recessed flanks of adjacent pairs of feet; and a maximum foot depth to base radius ratio of 0.51; and an angle of 41 degrees between pairs of relative recessed flanks of adjacent pairs of feet is also very advantageous.

[0013] The bottle may include five feet, but this is not exhaustive.

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

[0015] The bottle can be made of PET, PEF. Other plastics can also be used.

[0016] The invention also relates to a method for manufacturing a bottle for containing a carbonated beverage, the method comprising:

[0017] providing an openable blow mold cavity defining the shape of a bottle as described above;

[0018] Providing hollow preforms;

[0019] Temperature regulation of preforms;

[0020] inserting the preform into a blow mold cavity;

[0021] injecting a fluid pressurized at a pressure of less than 16 bar into the preform so that the preform is stretched outwardly and contacts the surface of the blow mold cavity so as to assume the shape of the bottle defined by the blow mold cavity;

[0022] The blow mold cavity is opened and the bottle formed therein is removed.

[0023] Due to the above-described bottle construction, the blowing pressure is significantly reduced compared to known bottle blow-molding methods.

[0024] Other features and advantages of the present invention will also appear from the following description.

[0025] In the accompanying drawings given as non-limiting examples:

[0026] Figure 1 is a full view of a bottle made of plastic;

[0027] Figure 2 is a view of the bottom of the bottle showing the hemispherical geometry;

[0028] Figure 3 is a view of the bottom of the bottle showing the petal-like formations of the feet and depressions;

[0029] Figure 4 is an example of the base radius of the bottle bottom;

[0030] Figure 5 yes Figure 4 Another view of the bottom portion shown;

[0031] Figure 6 is an illustration showing the angle between adjacent legs of the bottle bottom. DETAILED DESCRIPTION

[0032] The words "upper" and "lower" refer to a coordinate system in which the bottle stands on a surface with its neck at the top and its bottom at the bottom. The word "axial" refers to the main axis X passing through the center of the neck and the bottom of the bottle.

[0033] It should be understood that standard rounding rules apply throughout. Thus, an angle stated as 41 degrees means a range of 40.5 degrees to 41.4 degrees.

[0034] Figure 1 Shown is a general view of a bottle 1 which is produced by stretch blow moulding of a preform made of a thermoplastic material such as PET (ethylene terephthalate) or PEF (polyfuranacetate).

[0035] Said bottle 1 comprises, at the upper end, a neck 2 reinforced to support a closure (not shown) provided with an opening 3 which allows the contents of the bottle to be poured out or otherwise extracted, such as by using a straw. In the extension of the neck 2, the container 1 comprises, in its upper part, a shoulder 4 widening in a direction opposite to the neck 2, said shoulder 4 being extended by a transverse wall or body 5, which, in the embodiment represented, is of substantially cylindrical shape, rotated about the main axis X of the container 1. The body 5 terminates at its lower end in a bottom 6.

[0036] Figure 2 and Figure 3 The bottom 6 is shown in more detail in FIG. The bottom base shape or form of the bottom 6 is approximately a hemispherical surface S1. Arranged symmetrically about the axis X and extending downwardly from the bottom geometric shape S1 are a plurality of feet 7. The function of the feet is to make the bottle stand upright on a surface. In some arrangements, the plurality of feet consists of five feet. In other arrangements, the plurality of feet can be three, four, six, seven or more feet. Five feet are usually used because this can achieve a good balance between stability and manufacturing cost.

[0037] like Figure 3 As shown, a recessed portion 8 is provided between adjacent pairs of legs. Figure 2 and Figure 3 As shown, the bottom line 81 of each of these recesses 8 coincides with the underlying geometric shape S1. Figure 2 As shown by way of example, the hemispherical surface S1 is generated by the rotation of the bottom line 81 of the depression 8 formed by two adjacent legs 7 around the central axis of the bottle. The legs 7 together with the depression 8 form a petal-shaped bottom formation on which the bottle can stand vertically. The term petal-shaped should be understood as having the meaning given in the above introduction.

[0038] We will now proceed to define the parameters needed to describe the optimized bottom of the present invention.

[0039] Maximum foot depth

[0040] The superimposed surface S2 is the surface forming each leg 7, such as Figure 2 In addition, Figure 2 As depicted, the maximum foot depth F describes the size of the longest possible normal vector from the hemispherical surface S1 to a point on the surface S2. In other words, the maximum foot depth F is the maximum distance from the hemispherical surface to the superimposed surface S2 measured in a direction orthogonal to the hemispherical surface S1. It should be understood that the maximum foot depth F depends on the size and shape of each foot 7.

[0041] Base radius

[0042] See now Figure 4 and Figure 5 . When the bottle is placed upright on a flat surface 9, each of the feet 7 contacts the surface 8 at a foot surface contact area 101. The contact area may or may not be continuous. Within the contact area, there are contact points that are closer to the axis X and contact points that are further away from the axis X. As shown in the figure, the base radius S is defined as the radius of the (largest) circle formed by the (axis outermost) feet to the surface contact point 10. The base radius is very important for the stability of the bottle when standing on a flat surface.

[0043] Minimum transition radius

[0044] For example Figure 3 As shown, the bottom 6 does not present sharp edges, and the edges of each foot are rounded. The minimum radius within the geometry of each foot 7 is called the minimum transition radius R. The minimum transition radius R represents the radius of the chamfer that is the transition area between the foot 7 and the bottom and / or the rest of the bottle geometry. In other words, a bottle described as having a minimum radius of curvature of 7 mm at any part of the bottom means that there is no radius sharper than 7 mm locally within the bottom area.

[0045] Depression Angle between wings

[0046] like Figure 6 As depicted, the opposing sides or flanks 11a, 11b of adjacent legs 7 are opposite each other across alternating recesses 8. The angle α between pairs of opposing recess flanks 11a, 11b is a measure of the steepness of the recess. Expressed in mathematical terms, the angle between opposing flanks 11a, 11b is defined as the angle between the normal vectors of each pair of opposing flanks.

[0047] Bottom optimization

[0048] In accordance with the above objectives, the inventors have experimented with a number of bottom designs. For each design considered, tests were conducted to determine whether the mechanical properties of the bottle were sufficient for containing carbonated soft drinks. Specifically, the tests described in detail in the above introduction were conducted. These test items included: the ability to resist the appropriate internal pressures typically associated with carbonated soft drinks; the ability to resist a drop from 180 cm onto a steel plate; the ability to resist a stress cracking scenario, which involves placing a pressurized sodium hydroxide bottle solution; and the ability to resist temperature cycling.

[0049] Table 1 shows the results of the tests conducted in each of the 13 sample bottle designs. All test bottles were made of PET. At each stage of the test, more than 11 bottles of each design were tested. For the drop test, 25 bottles of each design were tested.

[0050] The rightmost column shows whether the bottle meets the mechanical criteria above. If the bottle remains intact in each test, it is marked "Pass". For bottles that fail the test, they are marked "Fail".

[0051] The second column from the right indicates the blow molding pressure required during the manufacturing process for each specific bottle. Also given are the parameters of the maximum foot depth to base radius ratio; the minimum transition radius; and the angle between the flanks of the recess for each bottle tested.

[0052]

[0053] Table 1

[0054] Bottle 1 represents an example of a commercially available prior art bottle. Although this bottle "passed" in terms of mechanical properties, it required a blow molding pressure of 22 bar to manufacture. Similarly, Bottle 2 was able to withstand the mechanical testing regimen, but at the expense of requiring a blow molding pressure of 22 bar during manufacture.

[0055] For bottles having a minimum radius of curvature of 7 mm between any part of the bottom, or specifically between the foot 7 and the rest of the bottle geometry, the inventors have determined that a bottle bottom design having the following combination of properties will not only achieve the desired mechanical properties but will only require a blowing pressure of 16 bar or less.

[0056] Most importantly, the inventors have determined that this result can be achieved with a ratio of maximum foot depth to base radius of 0.5 ± 0.01.

[0057] By limiting the design to these parameters, the objects of the present invention can be achieved. For example, bottles 3, 5, 10 and 13 of Table 1 are bottles according to the present invention. These bottles passed the mechanical testing program and thus gave the best results. Bottle configurations 3, 10 and 13 required a blow molding pressure of 16 bar during manufacture; bottle 5 was manufactured using a blow molding pressure of 14 bar. This pressure is significantly lower than currently known pressures.

[0058] Bottle manufacturing

[0059] A mold is provided having a cavity shaped to form the bottle. A temperature-conditioned hollow preform is inserted into the mold. In some arrangements, a stretch rod is used to stretch the preform along the longitudinal axis of the bottle. The stretch rod, which may extend along the longitudinal axis, is pushed downwardly, thereby longitudinally stretching the preform until the bottom of the preform is closely adjacent to the bottom of the cavity.

[0060] A fluid, usually a gas, is blown into the interior of the hollow preform, causing it to assume the shape of the mold. The introduction of the fluid can begin before the stretching rod has completed the longitudinal extension of the preform. Due to the construction of the bottle according to the invention with a bottom as described above, the pressure required for blow molding such a bottle is less than 16 bar. After cooling, the mold is removed from the bottle.

Claims

1. A bottle (1) for containing a carbonated beverage, the bottle comprising: Subject (5); A bottom portion (6) extending from the lower end of the body (5), the bottom portion having a substantially hemispherical bottom geometry (S1), the bottom portion comprising: a plurality of legs (7) protruding downwardly from the underlying geometric shape (S1); A recessed portion (8), the recessed portion separating adjacent pairs of legs (7), the bottom line (81) of each recessed portion (8) being substantially consistent with the bottom layer geometric shape (S1): The foot and the recess together form a petal-like foot formation having axial symmetry about the longitudinal axis (X) of the bottle; a maximum footing depth (F), the maximum footing depth being the maximum vertical distance from the underlying geometry (S1) to the footing surface (S2); a base radius (S), the base radius being the radius of the largest circle formed by the points (10) of contact with the feet and the flat surface (9) when the bottle stands vertically on a flat surface; It is characterized in that The ratio of the maximum foot depth to the base radius is 0.5±0.

01.

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

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

4. The bottle according to claim 3, wherein the ratio of the maximum foot depth to the base radius of the bottle is 0.51; and the angle between the pairs of opposing recessed flanks (11a, 11b) of adjacent pairs of feet (7) is 37 degrees.

5. The bottle according to claim 3, wherein the ratio of the maximum foot depth to the base radius of the bottle is 0.49; and the angle between the pairs of opposing recessed flanks (11a, 11b) of adjacent pairs of feet (7) is 44 degrees.

6. The bottle according to claim 3, wherein the ratio of the maximum foot depth to the base radius of the bottle is 0.51; and the angle between the pairs of opposing recessed flanks (11a, 11b) of adjacent pairs of feet (7) is 41 degrees.

7. The bottle according to claim 3, wherein the ratio of the maximum foot depth to the base radius of the bottle is 0.50; and the angle between the pairs of opposing recessed flanks (11a, 11b) of adjacent pairs of feet (7) is 44 degrees.

8. The bottle according to any one of claims 1 to 7, wherein the 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 bottle.

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

11. The bottle according to 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. A method for manufacturing a bottle for containing a carbonated beverage, the method comprising: providing an openable blow mould cavity defining the shape of a bottle according to any one of claims 1 to 12; Providing hollow preforms; regulating the temperature of the preform; inserting the preform into the blow mold cavity; injecting a fluid pressurized at a pressure of less than 16 bar into the preform so that the preform is stretched outward and contacts the surface of the blow mold cavity so as to assume the shape of the bottle defined by the blow mold cavity; The blow mold cavity is opened and the bottle formed therein is removed.

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