JP5641267B2 - Self-supporting container - Google Patents

Description

  The present invention relates to a free-standing container, and more particularly to a petal-like base for such a container. Such a container can be formed by blow molding of a plastic material such as polyethylene terephthalate (PET).

  As known in the art, the generic term “PET” here includes compositions that primarily contain polyethylene terephthalate, but can include other materials. For example, a suitable composition may include about 95% polyethylene terephthalate and 5% nylon. As is known in the art, these materials can be mixed or provided as different layers, such as by multi-layer injection molding or overmolding processes.

  Blow molded PET containers have long been used as beverage bottles. More recently, it has been proposed to use them as kegs for the transport, storage and dispensing of beverages such as beer. An example of such a keg is disclosed in WO2007 / 064277.

International Publication No. 2007/064277 Pamphlet

  The examples of WO2007 / 064277 are only given as background reference material, and the broad concept of the present invention is not limited to the specific use, material or manufacturing method of the container. However, the present invention has particular advantages in the context of a thin wall blow molded container of the type suitable for production from PET. It is in this context that the invention is described below in this specification.

  Early PET containers had simple hemispherical bases, which were constructed in a self-supporting manner by attaching a separate base forming part to the base. Although the hemispherical base is simple, lightweight and strong on its own, the addition of a separate base forming part can increase material and manufacturing costs and can be difficult to recycle.

  In order to make a PET container self-supporting without relying on a separate base forming part, it is now well known to provide an integrally formed petal-like base in the container. Here, the term “petal shape” is a multi-leg base shape in which a plurality of legs are arranged around the base in a rotational direction, and the resulting shape is a lower part of the container when in use. A shape resembling a petal of a flower when viewed from the top. The container usually comprises a cylindrical side wall with a circular horizontal cross section, in which case the legs are usually concentric with the circular cross section of the side wall and lie on a contact circle with a smaller diameter. These legs cooperate to provide a stable multipoint support for the container.

  There is a continuing need in container technology to reduce material and manufacturing costs and facilitate recycling. This is why not only integrated containers with petal-like bases have been adopted, but also containers can be manufactured more economically while maintaining high reliability functions during storage, transportation and use. Efforts to improve the petal-like base are continued. It is particularly desirable to reduce the amount of material required to give the container sufficient commercial integrity and stability. Even if the material savings per container is negligible, if it is replicated in thousands of millions of containers per year, the impact on manufacturing costs is enormous.

  Proper trade-off between material usage and container integrity is particularly important when the container is used as a pressure vessel. For example, the container may be used for storage, transport and dispensing of sparkling beverages such as beer. The beverage itself may contain carbonic acid or a propellant gas may be injected into the container at superatmospheric pressure to remove the beverage from the container. Such containers are required to withstand these internal pressures under environmental conditions. In addition to withstanding internal pressure, the container is also required to withstand rough handling during transport of the container.

  It is from this background that the present invention was devised. In one aspect, the present invention relates to a petal-like base for a self-supporting container, the base interrupting and projecting from the spherical base base contour to form a corresponding plurality of legs. A plurality of spheroidal leg forming portions.

  It is understood that since the leg portion has a spheroid shape, contact with a flat surface on which the base can rest is via a convex surface. Therefore, preferably the contact between any leg and the plane is via a point on the curved surface of that leg.

  In order to maximize the volume and strength of the container while minimizing material usage, the base base profile is preferably substantially hemispherical. The contour can be, for example, an oblate spheroid whose original line coincides with the central axis of the base. For the same reason, the leg forming part preferably has a longitudinal shape such as a partial ellipse or an ellipse. In a preferred embodiment of the present invention, the leg forming portion has an egg shape (partial egg shape), and in this case, the contact point of the leg portion is most simply the widest section of each leg forming portion. Is formed by being offset inward toward the inner end of the leg forming portion. In other words, the leg forming portions are tapered more at their outer diameter portions than at their inner diameter portions with respect to the central axis of the base.

  Preferably, the base is a forming part such as a leg forming part, and the shape thereof is substantially rotationally symmetric about the axis. For example, the shape of the spheroid, ellipse, oval, etc. forming the leg forming part is preferably substantially rotationally symmetric about the axis. Advantageously, by making these shapes forming the base rotationally symmetric, the materials used to form these structures can be minimized. At the same time, it is possible to maximize the internal volume of the base and also its strength.

  In order to form the legs with minimal material usage, the longitudinal leg formers preferably have respective longitudinal axes, which extend radially from the central axis of the base. It is located on the plane to be. The axes of the leg forming portions preferably extend outward and upward in a conical shape from the central axis of the base.

  Each leg forming part has an oval, preferably oval intersection with the base base contour. In order to reduce stress concentrations, the common part preferably has a concave cross section.

  In order to strengthen the base, the leg forming part preferably extends radially from the central protrusion. The protrusion has a substantially polygonal shape with the number of surfaces corresponding to the number of leg forming portions.

  The leg forming portions are preferably separated from each other by valleys, and these valleys can extend radially from the vertices of the polygonal protrusion, for example. In order to minimize material usage, the trough is preferably wider as it goes outward across the base. Each trough can include, for example, an inner portion and an outer portion, and the walls of the trough can be configured to branch more rapidly at the outer portion than at the inner portion. However, the wall of the valley portion can be configured to branch at both the inner portion and the outer portion of the valley portion.

  In plan view, each leg forming part can comprise an enlarged central region, from which the leg forming part can be configured to taper inward toward the inner end via the inner part. In that case, the inner part of the leg forming part is preferably arranged in a segmented state around the base. In order to minimize the amount of material used, each leg forming portion preferably tapers outward from the enlarged central region toward the outer end of the leg forming portion through the outer region in plan view. .

  The concept of the present invention extends to containers such as kegs and bottles comprising the base of the present invention. Preferably, the container is constructed by blow molding a preform, ideally made of PET.

  Preferably, when the material used is PET, the container has a ratio of an average pressure resistance to a material usage amount of 3 MPa / kg or more. More preferably, the ratio of the average pressure resistance to the amount of the material used is 3.75 MPa / kg or more. Preferably, the container has a volume ratio with respect to a material usage amount of 40 liters / kg or more. More preferably, the container has a volume to material usage ratio of 80 liters / kg or more.

  In order to make the understanding of the present invention easier, specific examples will be described below with reference to the accompanying drawings. In these drawings,

FIG. 1 is a plan view from below of a container comprising a petal-like base according to the present invention. FIG. 2 is a side view of the petal-like base of the container illustrated in FIG. FIG. 3 is a side sectional view of the petal-like base of the container shown in FIG. 4 (a), 4 (b) and 4 (c) are respectively below the container with the base illustrated in FIGS. 1-3, implemented in this example as a bottle with a capacity of 0.33 liters. It is a top view, a side view, and a perspective view. 5 (a), 5 (b) and 5 (c), respectively, below another container with a base illustrated in FIGS. 1-3, implemented in this example as a 20 liter capacity keg. It is a top view, a side view, and a perspective view. 6 (a), 6 (b) and 6 (c) are respectively a lower plan view of another container with a base according to the invention, in this example implemented as a bottle of 1.5 liter capacity. , Side view, and perspective view, and the base of this example is a modified example including seven legs. FIG. 7 is a bottom plan view of the container shown in FIG. 1, which in this example is marked by the section line of FIGS. 8 and 9. 8 is an enlarged partial side sectional view through the petal-like base of the container of FIG. 7 along the line VIII-VIII. 9 is an enlarged partial cross-sectional side view through the petal-like base of the container of FIG. 7 along the IX-IX cross-sectional line. FIG. 10 is a side view of a container having a five-legged petal base illustrated in FIGS. 1-3, implemented in this example as a 18 liter capacity keg with non-cylindrical sidewalls. 11 is a side view of a plastic preform that is blow molded into the 18 liter capacity keg shown in FIG. FIG. 12 is an enlarged side sectional view showing the container base shown in FIG. 3 together with the beverage dispensing tube in the container.

  Referring first to FIGS. 1 and 2 of the drawings, the container 10 of this example of the present invention is a blow molded PET hollow body. The body of the container 10 has a circular horizontal cross section, the radius of which extends in an orthogonal direction from a central longitudinal axis 12 that extends through the center of the closed base 14 of the container 10. Although not shown in FIGS. 1 and 2, a substantially cylindrical side wall with a neck portion thereon is disposed above the base 14. The side wall is integral with the lower end of the base 14 and terminates at the lower end, whereas the side wall is integral with the upper end of the neck at the top of the container 10; and It terminates at this upper end.

  The base or basic shape of the base 14 is a slightly flattened hemisphere, which is rotationally symmetric about the central axis 12 of the container 10. More generally, the base shape of the base 14 is an oval spheroid on its original line (which coincides with the central longitudinal axis 12) shorter than the diameter of the plane of the equatorial circle that intersects it. A rotationally symmetric ellipse having a diameter. This substantially hemispherical shape maximizes resistance to internal pressure, reduces stress concentration against cracking, and maximizes internal volume while minimizing material usage.

  According to the present invention, the base 14 further comprises integrally molded blister-like legs arranged in a petal shape around the base, which in this example are the central longitudinal axis. It is formed by five hollow egg-shaped leg forming portions 16 extending radially from the substantially pentagonal convex portion 18 which is relatively shallow on the core 12 at an equal angle. More generally, the leg forming part 16 is a long spheroid-shaped ellipse, where the long sphere is a sphere having a diameter along its original line larger than its equator diameter. .

  The original line 20 of the spheroidal leg forming portion 16 extends outward and upward in a radial plane that is spaced at an equal angle from the central longitudinal axis 12 of the container 10. Accordingly, the original line 20 of the leg forming portion 16 (see FIG. 2) is located on the virtual truncated conical surface surrounding the central longitudinal axis 12.

  The pair of leg forming portions 16 adjacent to each other in the circumferential direction are separated from each other by valley portions 22 that extend radially from the apex 24 of the pentagonal central projecting portion 18 at an equal angle. The floors of these valleys open at their outer ends to the outer part of the base 14 located radially outward beyond the leg forming part 16 along the spheroidal shape of the base 14. Further, each leg forming portion 16 and the central protrusion 18 are connected to each other via a transition portion that smoothly curves without a clear transition or discontinuity. Therefore, as shown in FIG. 3, a curved cross section is formed by the leg forming portion 16, the smoothly curved transition portion, and the central projecting portion 18.

  Similarly, as shown in FIG. 3, the convex central protrusion 18 has a radius of curvature r smaller than the general radius of curvature R of the spheroidal base 14, ie, R> r. Furthermore, the convex central protrusion 18 extends beyond the lowest vertex of the basal pace profile and, therefore, to a level below that in use. Further, the convex central projecting portion 18 extends to a level within the extension range of the leg forming portion 16, and therefore above the level in use.

  The leg forming portion 16 bulges outward from the basic spheroidal contour of the base 14 by an oval convex wall. The convex wall of each leg forming portion 16 is surrounded by a concave transition region 26 having an oval ring shape. The transition region 26 extends smoothly with a large radius of curvature into the spheroidal wall of the base, thereby reducing stress concentration and thus minimizing stress cracks. The transition region 26 of the leg forming portions 16 adjacent to each other in the circumferential direction forms a part of the valley portion 22 between the leg forming portions 16.

  Each leg forming portion 16 is generally oval (in this example, oval) in the lower plan view, and is the largest in the enlarged central region 28 between its inner end 30 and its outer end 32. The width has been reached. Accordingly, each leg forming portion 16 extends from the widest portion of the central region 28 inward along the inner portion 34 to the inner end 30 toward the central longitudinal axis 12 and along the outer portion 36. Tapering in the opposite direction from the central longitudinal axis 12 toward the outer end 32.

  In the lower plan view, the inner portion 34 tapering to the inside of the leg forming portion 16 is closely fitted between adjacent ones around the circular base 14 like an orange section. These inner portions 34 of the leg forming portion 16 can be substantially parallel in this example, but are narrow in the valleys 22 that are slightly wider in width as they extend outward from the pentagonal central protrusion 18. The inner portions 38 are alternately received and are separated from each other by the inner portions 38. However, if they extend outwardly beyond their widest part of the leg forming part 16 to their outer part 40, the troughs 22 are between the outer ends 32 of the leg forming part 16 adjacent to it. The width increases approximately exponentially between the tapered outer portions 36 of the leg forming portion 16 until the maximum width is reached.

  Accordingly, the gap between the leg forming portions 16 increases from the central longitudinal axis 12 along the valley 22 toward the outer diameter of the base 14. In contrast, in a conventionally known petal-like base such as that disclosed in EP 0671331, this gap is reduced.

  Viewed next from the side, the leg forming portion 16 extends to a level beyond the lowermost vertex of the base 14 formed by the central pentagonal protrusion 18 and, therefore, extends below it in use. . All of these leg forming portions 16 extend to the same level. Thus, at that level, each leg forming portion 16 forms a contact point 42 that is stably located on a flat support surface (not shown) orthogonal to the central longitudinal axis 12 of the container 10.

  FIG. 3 illustrates that the leg formers are somewhat oval shaped with the widest section in cross section offset slightly inward and downward toward their inner end 30.

The contact points 42 of the leg forming part 16 are arranged on the contact circle centered on the central longitudinal axis 12 of the container 10 and at equal intervals around it. The diameter (x) of the contact circle is related to the diameter (Dy) of the side wall of the container 10 in the following ratio.
Dy / 0.5x = k

  According to the present invention, k is preferably 3.6 to 5.5, more preferably 4.0 to 5.3, still more preferably 4.2 to 5.0, typically 4. 7. This is in contrast to a typical commercially available PET bottle whose corresponding ratio k is usually 2.5-3.5. This relatively large value of k in the present invention is due to the relatively small value of x. This is advantageous because it is small between the contact points 42 by a small contact circle and thus forms an inherently rigid diaphragm.

As a result, the central region in the contact circle between the contact points 42 of the leg forming portion 16 is extremely hard (rigid), and therefore has resistance to movement from the internal pressure to the burst pressure. The rigidity of the region within the contact circle is enhanced by the wavy wall formed by the inner part 34 of the leg forming part 16, the valley 22 between them and the central protrusion 18.

  The stiffness in the contact circle is important not only for high burst pressure but also for stability. This is because the lowest point on the central longitudinal axis (the lowest vertex of the base 14 formed by the central pentagonal protrusion 18) tends to be pushed down by internal pressure. If the lowest point moves until it comes into contact with the support surface in use, the container cannot rest stably on the contact point 42 of the leg forming part 16. The rigidity of the base shape of the present invention has a relatively short distance from the central apex of the base to the support surface compared to previously known configurations, which is advantageous for stability and volume with respect to the height of the container. It means that it has become.

  When an optional leg forming part 16 is viewed from the end (i.e. from the side of the inner container 10 towards the central longitudinal axis 12), the profile of the leg forming part 16 is that of the transition region 26 to each side. A substantially constant convex radius is formed between the concave radii. Conventional petal-like bases typically have a flatter surface that forms a V-shaped valley between the legs, which is detrimental to material usage and stress concentration. The stress concentration creates a region of the container that is particularly vulnerable to rupture at high internal pressures.

  The above configuration of the base 14 of the present invention is particularly suitable for containers for dispensing liquids under pressure. In particular, the large value of k increases the rigidity of the base and is therefore more suitable for maintaining stability while the container is subjected to high internal pressure. Furthermore, by increasing the value of k, it is possible to provide the convex central protrusion 18 at a lower position in the axial direction than would otherwise be possible in a container subjected to a high internal pressure. This makes it possible to maximize the amount of beverage that can be practically dispensed from the container 10. This advantage will be explained with reference to FIG. 12, where the same cross-sectional view of the container base 14 of FIG.

  In this context, the container is used as a beer keg 10 having a closed structure that is sealed to the cylindrical neck of the keg 10 in a push-in manner. The tube 120 is connected to the closed structure (not shown) and then extends along the central longitudinal axis 12 into the base of the keg 10. A lower end portion in the axial direction of the tube 120 extends into the central protrusion 18. The end of the tube 120 is located in the central protrusion 18 and hangs a little inside the apex of the central protrusion 18 so that the beverage is transferred from the keg 10 to the tube 120 or vice versa. An annular gap is provided that can pass in the direction. The shape of the central protrusion 18 also allows the axially lower end of the tube 120 to be properly positioned and held within the central protrusion during installation and use.

  In use, the keg 10 is maintained in an upright position when dispensing a beverage. The closed structure allows pressurized gas to be introduced into the head space of the keg 10 to allow the beverage to be removed via the tube 120. Since the axially lowermost end of the tube 120 is located in the central protrusion 18 and this central protrusion 18 is at a relatively low axial position in the keg 10, this allows most of the beverage in the keg 10 to be It is possible to reliably remove everything from it.

  By extending the tube 120 into one of the leg formers 16, it may be possible to further increase the amount of beverage that can be practically removed from the keg 10. In such a configuration, the tube 120 would need to be bent away from the central longitudinal axis 12 at its lower end. This may slightly increase the amount of beverage that can be dispensed from the keg 10, but this can complicate the process of attaching the closure structure and tube 120 to the keg 10. In particular, inserting a bent tube 120 into the keg 10 may require complex automated mounting operations. Further, by bending the tube 120 away from the central longitudinal axis 12, an uneven force may be applied to the closing structure in which the tube 120 is attached to the upper end in the axial direction. And this can reduce the reliability of the closing assembly, which is particularly a concern when the keg 10 is subjected to high internal pressure.

  The petal-like base of the present invention can be used for a wide range of containers, such as bottles and kegs. 4 (a), 4 (b) and 4 (c) and FIGS. 5 (a), 5 (b) and 5 (c), respectively, can typically be used for carbonated soft drinks. 1 illustrates a 5-leg base of the present invention applied to a 0.33 liter bottle, typically a 20 liter keg 46 that can be used for beer. These figures illustrate a feature that is omitted in FIGS. 1 and 2, ie, a substantially cylindrical side wall 48 surrounded by a neck 50. The side wall 48 is integral with the lower end portion of the base 14 and terminates at the lower end portion. The side wall 48 is integral with the upper end of the neck 50 at the top of the container and terminates at the upper end.

  FIG. 10 illustrates another five leg base of the present invention applied to an 18 liter capacity keg 104 with a non-cylindrical sidewall 108. In this example, the side wall 108 has a convex shape that is rotationally symmetric about the central longitudinal axis of the keg 104 and substantially follows the shape of an egg. At the lower end in the axial direction, the side wall is smoothly curved and extended to the spherical base base contour of the present invention. At the upper end in the axial direction that tapers larger than the lower end in the axial direction, the side wall is smoothly curved toward the concave neck of the keg 104. By forming the convex side wall 108 in this way, the resistance to internal pressure is maximized, the internal volume of the keg 104 is maximized, and the amount of material used is minimized. FIG. 11 is an enlarged side view of a plastic preform that is blow molded into the container illustrated in FIG.

  Other variations of the invention are possible without departing from the concept of the invention. For example, the modification of the base of the present invention shown in FIGS. 6 (a), 6 (b) and 6 (c) is applied to a bottle 52 having a capacity of 1.5 liters. This modification has seven leg forming portions 54 instead of five, and a substantially heptagonal central projecting portion 56 is formed between them. Similar to the five leg base variant, the seven leg base variant is 0.33 liter, 0.5 liter, 1 liter, 1.5 liter or more bottle, and 20 liters or other capacity. It is applicable to containers of any size such as keg.

  An odd number of legs is preferred for optimum stability, in which case at least 3 legs (in which case the central protrusion is approximately triangular), 7 or fewer legs are preferred, 5 or Seven legs are considered optimal.

  Without limiting the broadest scope defined in the claims, various dimensional features are exemplified below to confer the present invention.

  First, the table below shows a capacity comparison between a conventional base and the base of the present invention, where it is assumed that the base has five legs. The volumes in the table are shown in milliliters (ml). Here, the capacity refers to the internal capacity of the base, which is defined as the container portion below the cylindrical side wall of the container. It will be appreciated that the base of the present invention has a capacity of about five times that of a conventional petal-like container base, and is more advantageous for compactness and material usage for a given container capacity. .

  Second, the following dimensions help define the shape of the base for each of the above container volumes.

  FIGS. 7-9 provide additional dimensional information for a 20 liter keg having a five leg base 14. FIGS. 10 and 11 provide dimensional information for an 18 liter keg 104 having a five leg base and its preform 106, respectively.

  8 is a partial cross-sectional side view of the petal-like base of the 20 liter keg of FIG. 7 along the line VIII-VIII. This cross section intersects the leg forming portion 16 at its contact point 42 and is parallel to the central longitudinal axis 12 of the keg 10 and spaced away from this axis in a distance radial direction of 50 mm. In this cross section of the leg forming part 16, its contour is a convex radius of 23.0 mm which is substantially constant between the concave radius of 12.0 mm of the transition region 26 to each side.

  9 is a partial cross-sectional side view of the petal-like base of the 20 liter keg of FIG. 7 along the line IX-IX. The cross section is aligned with the central longitudinal axis 12 of the keg 10 and intersects the same leg forming portion 16 and its contact point 42 as shown in FIG. The diagram of FIG. 9 corresponds to the diagram of FIG. 3, but provides the following additional dimensional information for the 20 liter keg.

  These radius measurements are also applicable to points on the other leg forming portion 16 of the container 10. These points are typically located in any plane that is aligned with both the central longitudinal axis 12 of the container and the original line of a given leg former 16.

  In addition to the distance data, the following data was obtained from a pressure test showing a typical burst pressure of a 20 liter Keg 10 with a five leg petal base 14 according to the present invention. For comparison, a pressure test was also performed on a conventional petal-like base under similar conditions. These values represent the burst pressure in bar.

  Thus, it can be seen that the average burst pressure of the 20 liter keg with the 5 leg base is about 8.8 bar = 800 kPa. Furthermore, the material usage of the 20 liter keg corresponds to 0.234 kg of PET. Thus, ratios for pressure resistance, capacity and material usage can be derived for this 20 liter keg.

Ratio of average pressure resistance to amount of material used = 3.76 MPa / kg
Volume ratio to material usage = 85 liters / kg

  Although the shape and size are different, a similar ratio can be derived for a container with a base 14 according to the invention as well.

  FIG. 10 provides additional dimensional data corresponding to an 18 liter keg 104.

  FIG. 11 provides additional dimensional data corresponding to the preform 106 of the 18 liter keg 104 of FIG.

  The approximate burst pressure of this 18 liter keg with a 5 leg base is about 14 bar = 1400 kPa. The material usage of the 18 liter keg corresponds to 0.468 kg of PET. Thus, ratios to pressure resistance, capacity and material usage can be derived for this 18 liter keg.

Ratio of average pressure resistance to amount of material used = ˜3 MPa / kg
Volume ratio to material usage = 41 liters / kg

For a five leg base, the following ratios apply in these examples:
For a 20 liter keg,
Length of leg forming part along the original line / width of leg forming part across the original line = 1.35
Diameter of contact circle / width of leg forming part across original line = 1.68
Base base contour radius / side wall diameter = 0.57
Radius of base base contour / radius of transition from base base contour to side wall = 2.72
Radial protrusion of leg forming part exceeding radius of base base contour / radius of base base contour = 1.13

For bottles of various volumes,
Length of leg forming part along the original line / width of leg forming part across the original line = 1.47
Diameter of contact circle / width of leg forming portion across the original line = 1.83
Base base contour radius / side wall diameter = 0.58
Radius of base base contour / radius of transition from base base contour to side wall = 1.81
Radial protrusion of leg forming part exceeding radius of base base contour / radius of base base contour = 1.15

Similarly, for a seven leg base, the following ratios apply in these examples:
For a 20 liter keg,
Length of leg forming part along the original line / width of leg forming part across the original line = 1.44
Diameter of contact circle / width of leg forming section across the original line = 1.82
Base base contour radius / side wall diameter = 0.57
Radius of base base contour / radius of transition from base base contour to side wall = 2.72
Radial protrusion of leg forming part exceeding radius of base base contour / radius of base base contour = 1.13

For bottles of various volumes,
Length of leg forming part along the original line / width of leg forming part across the original line = 1.59
Diameter of contact circle / width of leg forming part across original line = 2.03
Base base contour radius / side wall diameter = 0.57
Radius of base base contour / radius of transition from base base contour to side wall = 1.8
Radial protrusion of leg forming part exceeding radius of base base contour / radius of base base contour = 1.15

  From the foregoing description, it will be apparent that the improved petal base shape of the present invention has various additional advantages. Its gently curved shape without sharp radii is advantageous to resist stress cracking. Significantly, the surface area is smaller than comparable conventional known configurations. Thus, for a given amount of resin, the present invention allows for a thicker wall and thus a stronger base. Alternatively, the weight and material usage can be reduced while maintaining the strength of the base. A rugged base is particularly important in applications where containers are exposed to high internal pressures and / or high temperatures, such as carbonated soft drinks, beer, high heat filling or pasteurized liquids.

Claims (29)

A petal-like base for a self-supporting container, comprising a spherical base base contour and a plurality of spheroidal leg formations that interrupt the base base contour and project from the contour to form corresponding legs have a part and,
Each of the leg forming portions has an oval common portion with a concave cross section that smoothly extends to the base base contour,
The leg forming portion extends radially from the central protrusion,
The central protrusion extends to a level beyond the lowest vertex of the base base contour and has a radius of curvature smaller than the radius of curvature of the base base contour;
The leg forming portion and the central projecting portion are connected to each other via a smoothly curved transition portion,
The curve of the transition portion is the reverse of the curve of the leg forming portion and the central protrusion,
The leg forming part, the transition part that smoothly curves, and the central projecting part cooperate to form a curved section,
A base in which a wavy wall portion is formed by an inner portion of the leg forming portion, a valley portion between the leg forming portions, and the central projecting portion . The base according to claim 1, wherein the basic base contour is an oblate sphere whose original line coincides with a central axis of the base.   The base according to claim 1 or 2, wherein the base base profile is substantially hemispherical.   The base according to claim 1, wherein the leg forming portion is an ellipse.   The base according to claim 4, wherein the leg forming portion is an oblong spheroid.   The base according to claim 4 or 5, wherein the leg forming portion has an oval shape.   The base according to claim 6, wherein the widest portion of the cross section of each leg forming portion is offset inward toward the inner end of the leg forming portion.   The base according to any one of claims 4 to 7, wherein the leg forming portions have respective longitudinal axes, and the axes are located on a plane extending in a radial direction from a central axis of the base. .   The base according to claim 8, wherein the axis of the leg forming portion extends outward in a conical shape from the central axis of the base.   The base according to claim 9, wherein the axis of the leg forming portion extends outward and upward from the central axis of the base.   The base according to claim 10, wherein the axis of the leg forming portion meets the central axis of the base at a position on the central axis of the base below the base. The base of claim 1 , wherein the intersection is oval. The base according to claim 1 , wherein the central protrusion is substantially convex with respect to the outside of the container. The central projection, a recess with respect to the interior of the container, the recess is in claim 1 or 13 is configured to hold the free end of the fluid delivery tube is positioned in the container The stated base. The base according to claim 1, 13 or 14 , wherein the central protrusion has a substantially polygonal shape, the number of surfaces of which corresponds to the number of the leg forming portions. The valleys, base according to 請 Motomeko 15 that are extending radially from the vertex of the polygonal projection. The base according to claim 16 , wherein the width of the valley portion increases as it goes outward across the base. 18. A base according to claim 17 , wherein each trough has an inner portion and an outer portion, and the walls of the trough are branched more sharply at the outer portion than at the inner portion. The base according to claim 18 , wherein the wall of the valley portion is branched at both the inner portion and the outer portion of the valley portion. In plan view, each leg forming section, base according to any one of claims 1 to 19 having an enlarged central region tapering to the inner end inwardly through the inner part of the leg forming section. The base according to claim 20 , wherein the inner portion of the leg forming portion is arranged in a state of being segmented around the base. The base according to claim 20 or 21 , wherein each leg forming portion tapers outwardly from the enlarged central portion to an outer end portion through an outer portion of the leg forming portion in plan view. A self-supporting container comprising the base according to any one of claims 1 to 22 . Each of the leg forming portions of the base has a diameter (x) of Dy / 0.5x = k, where k is 3.6-5.5, such that the side wall diameter of the container ( 24. A container according to claim 23 , forming contact points spaced apart from each other around a contact circle associated with Dy). The container according to claim 24 , wherein k is 4.0-5.3. The container according to claim 25 , wherein k is 4.2 to 5.0. 27. A container according to any one of claims 23 to 26 having a ratio of average burst pressure resistance to material usage of 3 MP / kg or more. 28. A container according to any one of claims 23 to 27 having a ratio of capacity to material usage of 40 liters / kg or more. Having a fluid delivery tube which is aligned with the central longitudinal axis of the container, any one of claims 23 to 28 which extends between the tube openings of the base and the container of the container Container as described in.

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