Container having a reinforced bottom and bottom of a mold for producing such a container

Abstract

The present invention relates to a container (1) provided with a body (5) and a bottom (6) comprising at least one peripheral heel (7), and a push-up (10) that extends from a central region (11) to the heel (7), the bottom (6) comprising at least one central pin (12), the push-up (10) comprising at least two grooves referred to as main grooves (13), characterized in that the bottom of each main groove (13) has a curved radial profile such that the depth of each main groove (13) decreases from the central pin (12) to the distal end thereof, the radial radius of curvature of the bottom of each main groove (13) being between 30% and 60% of the base diameter ΦA.

Description

Container with a reinforced base and mold base for manufacturing such a container

[0001] The present invention relates to the field of containers, in particular bottles or pots, manufactured by blow molding or stretch blow molding from blanks made of plastic material such as polyethylene terephthalate (PET) and more particularly from blanks obtained in whole or in part from recycled polyethylene terephthalate (rPET). State of the art

[0002] A container classically comprises a body delimiting the overall volume of the container, extended, at an upper end of the container, by a neck, through which the container is filled and emptied, and, at a lower end, by a bottom which closes the container.

[0003] The base must be able to withstand, without significant deformation, at least the hydrostatic pressure of the liquid column above it. There are many different base shapes, depending on the application. For example, for carbonated beverages (typically sodas), the bases are generally petal-shaped, comprising alternating hemispherical valleys and protruding feet, the ends of which form a base for the container. Such a base is described in document FR2959214, among others.

[0004] Document FR2959214 describes a thermoplastic container obtained by blow molding or blow-molding from a blank. This container comprises a petal-shaped base with projecting feet, separated by recessed valleys extending radially from a central area of ​​the base. Each foot has two sides, each bordering a valley laterally. Each foot has a side panel on each of its sides that projects laterally on the valley side.

[0005] The petaloid base appears as a relatively successful solution exhibiting good resistance to high internal pressures in the container (thanks to the hemispherical shape of the valleys).

[0006] However, the petal-like base requires a significant amount of material (approximately 18 to 23 g for a 0.5 L container), as well as a relatively high blowing pressure, to ensure proper molding of the hooves and valleys. These constraints appear justified, however, by the relatively high price at which the products are sold.

[0007] Petaloid bases, however, are unsuitable for applications involving still liquids (typically drinking water), where blowing pressure and the amount of material used (currently around 10 g for a 0.5 L container) are minimized. Furthermore, these petaloid bases are less stable on production line conveyors; a falling bottle with a petaloid base could cause the production line to stop.

[0008] A bottle base with a simple concave arch cannot withstand even a low pressure, on the order of 1 bar, without significant deformation. It has therefore been proposed to equip the base with radial ribs, designed to reinforce it and allow it to better resist deformations induced by pressure.

[0009] However, for certain applications involving still liquids sensitive to oxidation (particularly fruit juices, but also some still waters), it is becoming common practice to remove the air above the liquid and replace it with an inert gas (typically nitrogen). In practice, this operation, commonly called liquid inerting, is carried out by pouring a drop of liquefied inert gas onto the surface of the liquid, immediately before sealing the container. This operation, known as inerting (or nitrogenizing in the case of nitrogen), induces overpressure within the container. Even if seemingly slight (up to 1 bar), this overpressure is sufficient to significantly increase the stresses exerted on the bottom. This inerting operation can also be carried out using a process called nitrogen gas inerting, which consists of introducing nitrogen gas into the container after it has been filled and before it is sealed.This gaseous inerting operation is the most commonly used inerting method and has the advantage of not pressurizing the container.

[0010] Furthermore, the blow molding process typically involves placing a blank, such as a preform preheated to a temperature above the material's glass transition temperature, into a mold shaped to the container's cavity, and then injecting a pressurized fluid (particularly a gas such as air) into the blank. The blow molding process may be supplemented by pre-drawing the blank using a sliding rod.

[0011] The dual molecular orientation that the material undergoes during blowing (axial and radial, respectively parallel and perpendicular to the general axis of the container) gives the container a certain structural rigidity.

[0012] However, the market-driven reduction in the amount of material used to manufacture containers leads manufacturers to resort to manufacturing or shaping techniques to increase the rigidity of their containers, as bi-orientation proves insufficient. As a result, two containers of the same weight do not necessarily have the same mechanical performance (strength, rigidity).

[0013] A well-known process for increasing the rigidity of a container is "thermal fixing", which consists of heating the wall of the mold to thermally increase the degree of crystallinity as described in document FR2649035 in particular and which is usually used for HR (initials of the English term "heat resistant") applications, in which the container is filled while hot.

[0014] Document FR2649035 describes a process in which a container is molded by stretch-blowing from a polyethylene terephthalate (PET) preform. The preform body alone is heated to a temperature at which longitudinal and transverse stretching do not induce stress in the container material. The preform is then transferred into a mold, the walls of which are heated and maintained at a temperature lower than that of the preform body, where it is stretched longitudinally and blown. Thus, the two-way stretching ratio involved in transforming the preform into the container is between 7 and 9.

[0015] However, due to its cost and the reduced production rate it imposes, this type of process cannot be generalized to ordinary applications such as still water. Furthermore, this type of process would not improve the mechanical strength of the containers (bottles) used for still water. For these applications, the structural rigidity of the base depends primarily on its shape.

[0016] In this regard, it is known to stiffen the base by means of radial grooves. This is the case in particular for documents FR2753435, FR2883550 and FR2926034.

[0017] Document FR2753435 describes a container, such as a bottle, made of plastic, obtained by injection molding followed by stretching / blowing of a preform. The base of the container has reinforcing grooves that open at the junction between the base and the wall or extend slightly onto the wall. The other end of these grooves is at the theoretical extreme limit of the unstretched central portion of the base of the container. In this way, the grooves have an optimal length without ever ending in unstretched, and therefore amorphous, material, and the base has maximum resistance to creep and other stresses.

[0018] The base of this container maintains its structural integrity without tipping over as long as the volume and / or pressure conditions inside the container are normal. However, under extreme conditions, the base tends to collapse, even tipping over. For example, when the container is stored in high temperatures, typically when palletized outdoors in direct sunlight, the temperature of the contents can reach or exceed 50°C, and the pressure increase caused by the expansion of the contents can exceed the threshold at which the base tips over. The container then becomes unstable, with a high risk of the entire pallet collapsing.

[0019] Document FR2883550 describes a container, such as a bottle, made of thermoplastic material such as PET, manufactured by blow molding or stretch blow molding of a heated preform. The container has a base that is domed in the general shape of a spherical cap with its concavity facing outwards and defining an annular base. The base has reinforcing indentations projecting inwards and radiating around a central recess or central chimney. These indentations are generally trapezoidal in shape with their shorter side located towards the center of the base. The indentations have respective sides that form domed trapezoidal sectors with their concavity facing inwards and extend from the base to the central recess, connecting to it in the immediate vicinity of the upper end of the central recess.

[0020] We also know of document FR2926034 which discloses a mold base for a mold for manufacturing, by blow molding or stretch blow molding, containers, in particular bottles, from preforms in thermoplastic material, such as PET, said containers having a body and a base comprising a peripheral seat, shaped in a ring, internally connected to a central area forming an arch made up of a plurality of radiating impressions alternating with a quality of radiating protrusions, which are distributed angularly in an equidistant manner around a central axis of said base of container.The mold base comprises, for molding the central zone of the container base, several radiating projecting branches distributed angularly and equidistantly, extending approximately radially from the axis of the mold base; a central trunk having a lateral wall to which the branches are connected; and intervals forming segments of angular sectors regularly separating the branches from one another. Furthermore, each radiating projecting branch has an upper portion in the form of an inclined platform sloping down from the center towards the periphery with at least two points of inflection in the curve.

[0021] In theory, it would be possible to create deep recesses in the bottom (particularly a deep vault) to increase its mechanical strength. However, this design trick, however effective, requires both additional material, incompatible with the aforementioned weight reduction requirements, and high blowing pressure, incompatible with energy-saving requirements, which, on the contrary, necessitate a reduction in the blowing pressure required to form the container.

[0022] There is therefore a need for a container whose mechanical performance is improved with equivalent blowability (i.e. the container's ability to be formed by blowing), whose optimized bottom shape provides a good compromise between blowability and rigidity, including for containers made from recycled PET, known as rPET, which has different mechanical properties than PET, whose bottom offers good resistance to turning over, and which, under extreme conditions of pressure and / or internal volume, can remain stable and whose manufacturing rate is higher without the appearance of undulations on the base. Disclosure of the invention

[0023] One of the aims of the invention is therefore to remedy all or part of these disadvantages by proposing a container of simple and inexpensive design, obtained from recycled PET known as rPET, exhibiting good resistance to the collapse of the bottom arch, requiring only a minimum of thermoplastic material and easy to conform correctly under the usual conditions of blow molding or stretch blow molding of containers intended for flat liquids.

[0024] Another objective of the invention is to provide a base without ribs extending up onto the heel, for aesthetic reasons in accordance with current market trends concerning sensitive products, while offering a structure that allows high speeds without unwinding of the base at the machine exit and that presents increased resistance to the mechanical stresses caused by rPET (drop test).

[0025] To this end, and in accordance with the invention, a plastic container is proposed having a body and a base extending from a lower end of the body, said body comprising at its upper end a shoulder and a neck, and the base comprising at least one peripheral heel defining a seat, and an arch extending from a central area to said heel, said heel rising on a connecting wall with the wall of the container body, said base comprising at least one central pin having a generally frustoconical or cylindrical lateral wall of revolution about the longitudinal X axis of the container and whose concavity is oriented towards the seat, said arch extending from said central pin to said heel, and the arch comprising at least two so-called main grooves extending radially from the central pin towards the seat,the concavity of said main grooves being oriented towards the seating plane and said main grooves being angularly distributed around said central pin; said vessel is remarkable in that the bottom of each main groove has a curved radial profile such that the depth of each main groove decreases from the central pin to its distal end, the radial radius of curvature of the bottom of each main groove being between 30% and 60% of the seating diameter, and in that the bottom of each main groove has a substantially constant width L1 from the central pin to a distance of about 40% of the total branch length, i.e. in the first section of the main groove, and an increasing width L2 from the end of said first section to the distal end of the main groove.

[0026] Advantageously, the width L1 in the first section of each main groove is between 1% and 6% of the seat diameter, and preferably equal to 3% of said seat diameter.

[0027] Furthermore, the width L2, between the end of the first section and the distal end of the main groove, is between 200% and 700% of the width L1 and, preferably, equal to 393% of said width L1.

[0028] In addition, the distal end of each main groove extends to a distance from the seat of between 8% and 20% of the value of said seat diameter and preferably extends to a distance from the seat of about 14% of the value of said seat diameter.

[0029] Preferably, the maximum depth of each main groove is between 6% and 18% of the seat diameter and preferably is about equal to 8% of said seat diameter.

[0030] Advantageously, the distal end of each main groove extends to a distance from the seat of approximately 14% of the value of said seat diameter.

[0031] Furthermore, the radial radius of curvature of the bottom of each main groove is equal to 38.5% of the seat diameter.

[0032] Furthermore, the bottom of each main groove has, in cross-section of said main groove, a curvilinear shape whose radius of curvature is variable from the central pin to its distal end.

[0033] The said radius of curvature of the bottom of each main groove is increasing from the central pin to its distal end.

[0034] Preferably, said radius of curvature of the bottom of each main groove is substantially constant from the central pin to a distance of about 40% of the total length of the branch, representing a first section of the main groove, and said radius of curvature of the bottom of each main groove is increasing from the end of said first section to the distal end of the main groove.

[0035] Furthermore, the vault has between two and six so-called secondary grooves extending radially from the central post towards the base along a length less than that of the main grooves, the concavity of said secondary grooves being oriented towards the base plane and said secondary grooves being angularly distributed around said central post extending between two main grooves.

[0036] The distal end of each secondary groove extends to a distance from the seat of between 12% and 25% of the value of said seat diameter and preferably extends to a distance from the seat of about 19% of the value of said seat diameter.

[0037] Furthermore, the bottom of each secondary groove has a curved radial profile such that the depth of each secondary groove decreases from the central pin to its distal end.

[0038] Furthermore, the maximum depth of each secondary groove is between 6% and 18% of the seat diameter and preferably is equal to about 8% of the seat diameter.

[0039] Said radial radius of curvature of the bottom of each secondary groove is between 25% and 55% of the seat diameter and, preferably, the radial radius of curvature of the bottom of each secondary groove is equal to 31.2% of the seat diameter.

[0040] Furthermore, the bottom of each secondary groove has, in cross-section of said secondary groove, a curvilinear shape whose radius of curvature is constant or variable from the central pin to its distal end.

[0041] Advantageously, the bottom of each secondary groove has a variable width from the central pin to its distal end, the bottom having a width L3 at the central pin and a width L4 at the distal end of the secondary groove.

[0042] Preferably, the width L3 of the bottom of each secondary groove is between 1 and 7% of the bearing diameter and, preferably, is equal to 3.5% of said bearing diameter and the width L4 of the bottom of each secondary groove is between 30% and 130% of the width L3 and, preferably, is equal to 80% of the width L3.

[0043] Furthermore, the said vault has a height of between 11% and 18% of the base diameter.

[0044] In addition, the central plinth has a diameter between 15% and 30% of the base diameter and overhangs the vault by a height between 9% and 18% of the said base diameter and, preferably, by a height of 12.6% of the said base diameter.

[0045] Advantageously, the vault has a substantially spherical shape of radius R centered on the longitudinal axis of the container, said radius R of the vault being between 70% and 120% of the base diameter.

[0046] The said radius R of the vault is, preferably, equal to 86% of the base diameter.

[0047] Furthermore, the base of the central pin consists of a spherical cap whose concavity is oriented towards the base and whose radius of curvature is between 25% and 75% of the base diameter and, preferably, is equal to 50% of the base diameter.

[0048] Furthermore, the central pawn is composed of at least three consecutive rays from its base to the vault.

[0049] Furthermore, the width of the seat is between 0.5% and 5% of the seat diameter and preferably is equal to 2.4% of the seat diameter.

[0050] Another object of the invention relates to a mold base for the manufacture of a container from a plastic preform, said mold base being able to be mounted at one end of a mold comprising two walls movable relative to each other and intended to form the body of the container, said mold base comprising at least a first annular part intended to form at least in part the heel, i.e. the seating surface, a second dome-shaped part intended to come into contact with an amorphous central zone of the preform to form the arch, characterized in that said second part is arranged so as to produce a container comprising a base according to the invention.

[0051] Other advantages and features will become clearer from the following description of several embodiments, given by way of non-limiting examples, of the container and the mold base for manufacturing said container according to the invention, with reference to the attached drawings in which:

[0052] is a perspective view from below of a plastic container according to the invention,

[0053] is a perspective view from below of the bottom of the plastic container according to the invention,

[0054] is a bottom view of the base of the plastic container according to the invention,

[0055] is a torn top-down perspective view of the bottom of the plastic container according to the invention,

[0056] is a torn side view of the bottom of the plastic container according to the invention, with dimensions,

[0057] is a top view of the bottom of the plastic container according to the invention, with dimensions,

[0058] is a second torn side view of the bottom of the plastic container according to the invention, with dimensions,

[0059] is a top perspective view of a variant embodiment of the bottom of the plastic container according to the invention,

[0060] is a bottom view of the embodiment variant of the bottom of the plastic container according to the invention shown in the,

[0061] is a top-view perspective of a second embodiment of the bottom of the plastic container according to the invention,

[0062] is a side view of the second embodiment of the bottom of the plastic container according to the invention shown in the,

[0063] is a radial cross-sectional view of the second embodiment of the bottom of the plastic container according to the invention, shown in Figures 10 and 11.

[0064] is an exploded perspective view of a mold, including a mold base, for the manufacture of a container according to the invention. Method of embodying the invention

[0065] In the following description of the container and the mold base for obtaining said container according to the invention, the same numerical references designate the same elements. Furthermore, the different views are not necessarily drawn to scale.

[0066] With reference to the, the container 1 according to the invention consists, in this case, of a bottle made by stretch blow molding from a preform in thermoplastic material, for example in PET (polyethylene terephthalate) and / or rPET (recycled polyethylene terephthalate), or similar.

[0067] The said container 1 includes, at an upper end, a neck 2, fitted with a mouth 3. In the extension of the neck 2, towards the lower end of the container 1, the latter usually includes, in its upper part, a shoulder 4 going outwards in the opposite direction to the neck 2, this shoulder 4 being extended by a lateral wall or body 5, generally substantially cylindrical in shape of revolution about a vertical longitudinal axis X, represented in dashed lines, of the container 1.

[0068] The container 1 further comprises a base 6 extending opposite the neck 2 from a lower end of the body 5. This base 6 includes a peripheral flange 7 in the form of an annular ridge extending substantially axially in line with the body 5. The flange 7 terminates in a support 8, also called a base, perpendicular to the longitudinal axis X of the container 1. This base 8 defines the lower end of the container 1 and allows the container 1 to be placed vertically on a flat surface. Furthermore, this flange 7 extends up a wall 9, called a connecting wall, to the wall of the body 5 of the container 1.

[0069] We denote ΦA the diameter of the base 8, the term "diameter" covering not only the case (illustrated) where the container 1 (and therefore the base 6) has a circular contour, but also the case where the container 1 would have a polygonal contour (for example square), in which case the term "diameter" would designate the diameter of the circle in which this polygon would be inscribed without going out of the scope of the invention.

[0070] Furthermore, the base 6 also includes a concave vault 10, in the form of a substantially spherical cap with its concavity facing outwards from the container 1 in the absence of constraint, i.e. in the absence of contents in the container 1. The vault 10 extends from the heel 7 to a central area 11 of the base 6 forming a central pin 12 projecting towards the inside of the container 1, with in its center an amorphous pellet 12b which corresponds to the injection zone of the material constituting the preform used to make the container and can fulfill a centering function during the blow forming of the container 1.

[0071] Furthermore, with reference to figures 2 to 7, said base 6 comprises a central pin 12 having a lateral wall that is generally frustoconical or cylindrical of revolution around the longitudinal axis of the container and whose concavity is oriented towards the base 8, said vault 10 extending from the base of said central pin 12 to said heel 7, and vault 10 comprises four main grooves 13 extending radially from the central pin 12 towards the base 8, the concavity of said main grooves 13 being oriented towards the base 8 and said main grooves 13 being angularly distributed around said central pin 12.

[0072] In this particular embodiment, said base 6 has only four main grooves 13; however, said base 6 may have between two and six main grooves 13 depending, in particular, on the dimensions of said container 1.

[0073] Furthermore, the distal end of each main groove 13 extends to a distance from the seat 8 of approximately 14% of the value of said seat diameter ΦA. The bottom of each main groove 13 has a curved radial profile such that the depth of each main groove 13 decreases from the central pin 12 to its distal end. Said radial radius of curvature R5 of the bottom of each main groove 13 is between 30% and 60% of the seat diameter ΦA and, preferably, is equal to 38.5% of the seat diameter ΦA.

[0074] The bottom of each main groove 13, in cross-section, has a curvilinear shape with a variable radius of curvature from the central pin 12 to its distal end. In the preferred embodiment shown in the figures, the radius of curvature of the bottom of each main groove 13 is substantially constant from the central pin 12 to a distance of approximately 40% of the total length of the main groove 13, representing a first section of the main groove, and the radius of curvature of the bottom of each main groove 13 increases from the end of this first section to the distal end of the main groove 13.

[0075] Furthermore, at the same time, the bottom of each main groove 13 has a substantially constant width L1 from the central pin 12 to a distance of approximately 40% of the total length of said main groove 13, i.e., in the first section of the main groove 13, and an increasing width L2 from the end of said first section to the distal end of the main groove 13. Preferably, the width L1 in the first section of each main groove 13 is between 1% and 6% of the bearing diameter ΦA, and preferably, is equal to 3% of said bearing diameter ΦA. In addition, the width L2, between the end of the first section and the distal end of the main groove 13, is between 200% and 700% of the width L1 and, preferably, is equal to 393% of said width L1.

[0076] In addition, the distal end of each main groove extends to a distance from the seat of between 8% and 20% of the value of said seat diameter and preferably extends to a distance from the seat of about 14% of the value of said seat diameter.

[0077] Preferably, the maximum depth of each main groove is between 6% and 18% of the seat diameter and preferably is about equal to 8% of said seat diameter.

[0078] According to an alternative embodiment, not shown in the figures, the radius of curvature of the bottom of each main groove 13 may be increasing from the central pin 13 to its distal end.

[0079] Furthermore, the vault 10 has four so-called secondary grooves 14 extending radially from the central pin 12 towards the course 8 along a length less than that of the main grooves 13, the concavity of said secondary grooves 14 being oriented towards the course 8 and said secondary grooves 14 being angularly distributed around said central pin 12 extending between two main grooves 13.

[0080] In this particular embodiment, the base 6 thus comprises four main grooves 13 and four secondary grooves 14; however, the base 6 may comprise between two and six main grooves 13 and between two and six secondary grooves 14, said base 6 preferably comprising the same number of main grooves 13 and secondary grooves 14, without departing from the scope of the invention.

[0081] It will be observed that, in this particular embodiment, the secondary grooves 14 are contiguous with the main grooves 13 at the central pin 12; However, it is quite clear that the secondary grooves 14 and the main grooves 13 may not be contiguous at the central pin 12 without going out of the scope of the invention.

[0082] The distal end of each secondary groove 14 extends from the seat 8 to a distance of between 12% and 25% of the value of said seat diameter ΦA and, preferably, extends to a distance from the seat 8 of approximately 19% of said seat diameter ΦA. Furthermore, the bottom of each secondary groove 14 has a curved radial profile such that the depth of each secondary groove 14 decreases from the central pin 12 to its distal end. The maximum depth of each secondary groove 14 is between 6% and 18% of the seat diameter ΦA and, preferably, is approximately 8% of the seat diameter ΦA.

[0083] The said radial radius of curvature R6 of the bottom of each secondary groove 14 is between 25% and 55% of the seat diameter ΦA and, preferably, is at 31.2% of said seat diameter ΦA.

[0084] Furthermore, the bottom of each secondary groove 14 has, in cross-section of said secondary groove 14, a curvilinear shape whose radius of curvature is constant or variable from the central pin 12 to its distal end.

[0085] Advantageously, the bottom of each secondary groove 14 has a variable width, such as a decreasing width, for example, from the central pin 12 to its distal end, with the bottom having a width L3 at the central pin 12 and a width L4 at the distal end of the secondary groove 14. This width L3 of the bottom of each secondary groove 14 is between 1% and 7% of the bearing diameter ΦA and, preferably, is equal to 3.5% of said bearing diameter ΦA. Furthermore, the width L4 of the bottom of each secondary groove 14 is between 30% and 130% of the width L3 and, preferably, is equal to 80% of said width L3.

[0086] Furthermore, said vault 10 has a height Hv between 11% and 18% of the bearing diameter ΦA and said central post 12 has a diameter ΦPu between 15% and 25% of the bearing diameter ΦA and said central post 12 overhangs vault 10 by a height Hpu between 9% and 18% of said bearing diameter ΦA and, preferably, by a height of 12.6% of said bearing diameter ΦA.

[0087] Advantageously, the vault 10 has a substantially spherical shape of radius R centered on the longitudinal axis of the container 1, said radius R of the vault 10 being between 70% and 120% of the base diameter ΦA and, preferably, said radius R of the vault 10 is equal to 86% of the base diameter ΦA.

[0088] Furthermore, the base of the central pin 12 consists of a spherical cap whose concavity is oriented towards the base 8 and whose radius of curvature R1 is between 25% and 75% of the base diameter ΦA and, preferably, is equal to 50% of the base diameter ΦA. Also advantageously, said central pin 12, i.e., the lateral wall of said central pin, is composed of at least three consecutive radii from its base to the arch 10. Preferably, the radius of curvature R1a of the lateral wall of the central pin 12 is between 25% and 75% of the base diameter ΦA and, preferably, is equal to 50% of said base diameter ΦA.

[0089] Furthermore, the width p of the seat 8 is between 0.5% and 5% of the seat diameter ΦA and, preferably, said width p of the seat 8 is equal to 2.4% of the seat diameter ΦA.

[0090] According to a first embodiment of the container according to the invention, with reference to Figures 8 and 9, said container 1 comprises, in the same way as before, a neck 2, provided with a mouth 3, a shoulder 4 flaring out in the opposite direction to the neck 2, this shoulder 4 being extended by a side wall or body 5, generally substantially cylindrical in shape of revolution about a vertical longitudinal axis, shown in Figures 8 and 9 and a bottom 6 which extends opposite the neck 2, from a lower end of the body 5.

[0091] The base 6 comprises a peripheral ridge 7 in the form of an annular bead extending substantially axially in line with the body 5. The ridge 7 terminates in a support 8, also called a base, perpendicular to the longitudinal axis of the container 1. This base 8 defines the lower end of the container 1 and allows the container 1 to be placed vertically on a flat surface. Furthermore, the ridge 7 extends up a wall 9, called a connecting wall, to the wall of the body 5 of the container 1.

[0092] We denote ΦA the diameter of the base 8, the term "diameter" covering not only the case (illustrated) where the container 1 (and therefore the base 6) has a circular contour, but also the case where the container 1 would have a polygonal contour (for example square), in which case the term "diameter" would designate the diameter of the circle in which this polygon would be inscribed without going out of the scope of the invention.

[0093] Furthermore, the base 6 also includes a concave vault 10, in the form of a substantially spherical cap with its concavity facing outwards from the container 1 in the absence of constraint, i.e. in the absence of contents in the container 1. The vault 10 extends from the heel 7 to a central area 11 of the base 6 forming a central pin 12 projecting towards the inside of the container 1, with in its center an amorphous pellet 13 which corresponds to the injection zone of the material constituting the preform used to make the container and can fulfill a centering function during the blow forming of the container 1.

[0094] Furthermore, with reference to figures 8 and 9, said base 6 comprises a central pin 12 whose concavity is oriented towards the course 8, said vault 10 extending from the base of said central pin 12 to said heel 7, and vault 10 comprises four main grooves 13 extending radially from the central pin 12 towards the course 8, the concavity of said main grooves 13 being oriented towards the course 8 and said main grooves 13 being angularly distributed around said central pin 12.

[0095] This embodiment differs from the one previously described in that the central pin 12 does not have a generally frustoconical or cylindrical lateral wall of revolution about the longitudinal axis of the container, but rather a substantially cylindrical or frustoconical wall having three lobes in cross-section. In other words, in this embodiment, the central pin 12 does not have a shape of revolution about the longitudinal axis of the container.

[0096] It is quite clear that the central pawn 12 can have any shape without going outside the scope of the invention.

[0097] Furthermore, in the same way as before, the vault 10 has four so-called secondary grooves 14 extending radially from the central pin 12 towards the course 8 along a length less than that of the main grooves 13, the concavity of said secondary grooves 14 being oriented towards the course 8 and said secondary grooves 14 being angularly distributed around said central pin 12 extending between two main grooves 13.

[0098] It is quite clear that the vault 10, the central pin 12, the main grooves 13 and the secondary grooves 14 in particular have the same characteristics as those described previously.

[0099] According to a second embodiment of the container according to the invention, with reference to figures 10 to 12, said container 1 comprises, in the same way as before, a neck 2, provided with a mouth 3, a shoulder 4 flaring out in the opposite direction to the neck 2, this shoulder 4 being extended by a side wall or body 5, generally substantially cylindrical in shape of revolution about a vertical longitudinal axis, shown in figures 8 and 9 and a bottom 6 which extends opposite the neck 2, from a lower end of the body 5.

[0100] The base 6 comprises a peripheral ridge 7 in the form of an annular bead extending substantially axially in line with the body 5. The ridge 7 terminates in a support 8, also called a base, perpendicular to the longitudinal axis of the container 1. This base 8 defines the lower end of the container 1 and allows the container 1 to be placed vertically on a flat surface. Furthermore, the ridge 7 extends up a wall 9, called a connecting wall, to the wall of the body 5 of the container 1.

[0101] We denote ΦA the diameter of the base 8, the term "diameter" covering not only the case (illustrated) where the container 1 (and therefore the base 6) has a circular contour, but also the case where the container 1 would have a polygonal contour (for example square), in which case the term "diameter" would designate the diameter of the circle in which this polygon would be inscribed without going out of the scope of the invention.

[0102] Furthermore, base 6 also includes a vault 10 that is substantially concave. This embodiment differs from the embodiments previously described in that said vault 10 does not take the form of a substantially spherical cap with its concavity facing outwards from the container 1 in the absence of stress, i.e., in the absence of contents in the container 1, but rather takes the form of several cylindrical portions 10a, 10b whose diameter decreases from the heel 7 to the central zone 11, i.e., to the central pin 12. The vault 10 extends from the heel 7 to the central zone 11 of the base 6, forming a central pin 12 projecting inwards from the container 1, with at its center an amorphous pellet 13 which corresponds to the injection zone of the material constituting the preform used to make the container and can fulfill a centering function during the blow molding of the container 1.

[0103] Furthermore, said base 6 has a central pin 12 whose concavity is oriented towards the course 8, said vault 10 extending from the base of said central pin 12 to said heel 7, and vault 10 has four main grooves 13 extending radially from the central pin 12 towards the course 8, the concavity of said main grooves 13 being oriented towards the course 8 and said main grooves 13 being angularly distributed around said central pin 12.

[0104] In this embodiment, said central pin 12 has a lateral wall that is generally frustoconical or cylindrical of revolution around the longitudinal axis of the container; however, it is quite clear that said central pin 12 may have a substantially cylindrical or frustoconical wall having in straight section three lobes as described above, or any other shape whatsoever, without going out of the scope of the invention.

[0105] Furthermore, in the same way as before, the vault 10 has four so-called secondary grooves 14 extending radially from the central pin 12 towards the course 8 along a length less than that of the main grooves 13, the concavity of said secondary grooves 14 being oriented towards the course 8 and said secondary grooves 14 being angularly distributed around said central pin 12 extending between two main grooves 13.

[0106] It is quite clear that the vault 10, the central pin 12, the main grooves 13 and the secondary grooves 14 in particular have the same characteristics as those described previously.

[0107] With reference to the, a molding unit 19 according to the invention is described for forming, from a blank, usually typically a preform, a container according to the invention, such as a bottle or a can, according to the invention.

[0108] The molding unit 19, referred to in the figure, comprises a mold 20 having a lateral wall 21 that defines a cavity 22 in the shape of a portion of the container. The mold 20 further comprises a base 23 in the shape of the base of the container, the mold 20 being made of metal, for example, steel or aluminum (this term also covering aluminum alloys). The cavity 22, and ultimately the container 20, extends along a principal axis X that defines a vertical direction. Any plane perpendicular to the principal axis X is said to be horizontal.According to an embodiment illustrated in the drawings, the side wall 21 comprises two half-molds 20a, 20b, each defining a half-impression 24a, 24b of the body of the container and mounted in rotation relative to each other around a common axis formed by a hinge, not shown in the figures, between an open position, in which the half-molds 20a, 20b are angularly separated from each other and the bottom of the mold 23 is lowered relative to the half-molds 20a, 20b to allow the introduction of the blank and the evacuation of the formed container, and a closed position, in which the half-molds 20a, 20b are applied against each other and enclose the bottom of the mold 23 between them, as shown in figures 6 to 8, to form the cavity 22 and define the impression of the container to be formed.Thus, the said mold base 23 is suitable for being mounted movably in the mold 20 comprising two walls movable relative to each other and intended to form the body of the container.

[0109] Finally, it is quite clear that the examples we have just given are only particular illustrations and in no way limiting as to the fields of application of the invention.

Claims

Plastic container (1) having a body (5) and a base (6) extending from a lower end of the body (5), said body (5) having at its upper end a shoulder (4) and a neck (2), and the base (6) having at least a peripheral heel (7) defining a seat (8), and an arch (10) extending from a central area (11) to said heel (7), said heel (7) rising on a connecting wall (9) with the wall of the body (5) of the container (1), said base (6) having at least a central pin (12) having a lateral wall that is generally frustoconical or cylindrical of revolution about the longitudinal axis X of the container (1) and whose concavity is oriented towards the seat (8), said arch (10) extending from said central pin (12) to said heel (7), and the arch (10) having at least two grooves called main grooves (13) extending radially from the central pin (12) towards the base (8),the concavity of said main grooves (13) being oriented towards the bearing plane and said main grooves (13) being angularly distributed around said central pin (12), characterized in that the bottom of each main groove (13) has a curved radial profile such that the depth of each main groove (13) decreases from the central pin (12) to its distal end, the radial radius of curvature of the bottom of each main groove (13) being between 30% and 60% of the bearing diameter ΦA, and in that the bottom of each main groove (13) has a substantially constant width L1 from the central pin (12) to a distance of approximately 40% of the total length of the branch, i.e. in the first section of the main groove (13), and an increasing width L2 from the end of said first section to the distal end of the main groove (13). Container (1) according to claim 1 characterized in that the width L1 in the first section of each main groove (13) is between 1% and 6% of the seat diameter ΦA, and preferably equal to 3% of said seat diameter ΦA. Container (1) according to any one of claims 1 or 2 characterized in that the width L2, between the end of the first section and the distal end of the main groove (13), is between 200% and 700% of the width L1 and, preferably equal to 393% of said width L1. Container (1) according to any one of claims 1 to 3 characterized in that the distal end of each main groove (13) extends to a distance from the seat 8 of between 8% and 20% of the value of said seat diameter ΦA. Container (1) according to claim 4 characterized in that the distal end of each main groove (13) extends to a distance from the seat (8) of approximately 14% of the value of said seat diameter ΦA. Container (1) according to any one of claims 1 to 5 characterized in that the maximum depth of each main groove (13) is between 6% and 18% of the seat diameter ΦA. Container (1) according to claim 6 characterized in that the maximum depth of each main groove (13) is about 8% of the seat diameter ΦA. Container (1) according to any one of claims 1 to 7 characterized in that the radial radius of curvature R5 of the bottom of each main groove (13) is equal to 38.5% of the seat diameter ΦA. Container (1) according to any one of claims 1 to 8 characterized in that the bottom of each main groove (13) has, in cross-section of said main groove (13), a curvilinear shape whose radius of curvature is variable from the central pin (12) to its distal end. Container (1) according to claim 9 characterized in that said radius of curvature of the bottom of each main groove (13) is increasing from the central pin (12) to its distal end. Container (1) according to claim 9 characterized in that said radius of curvature of the bottom of each main groove (13) is substantially constant from the central pin (12) to a distance of about 40% of the total length of the arm, representing a first section of the main groove (13), and said radius of curvature of the bottom of each main groove (13) is increasing from the end of said first section to the distal end of the main groove (13). Container (1) according to any one of claims 1 to 11 characterized in that the vault (10) comprises between two and six so-called secondary grooves (14) extending radially from the central pin (12) towards the seat (8) over a length less than that of the main grooves (13), the concavity of said secondary grooves (14) being oriented towards the seat plane and said secondary grooves (14) being angularly distributed around said central pin (12) extending between two main grooves (13). Container (1) according to claim 12 characterized in that the distal end of each secondary groove (14) extends to a distance from the seat (8) between 12% and 25% of the value of said seat diameter ΦA. Container (1) according to claim 13 characterized in that the distal end of each secondary groove (14) extends to a distance from the seat of approximately 19% of the value of said seat diameter ΦA. Container (1) according to any one of claims 12 or 13 characterized in that the bottom of each secondary groove (14) has a curved radial profile such that the depth of each secondary groove (14) decreases from the central pin (12) to its distal end. Container (1) according to any one of claims 12 to 15 characterized in that the maximum depth of each secondary groove (14) is between 6% and 18% of the seat diameter ΦA. Container (1) according to claim 16 characterized in that the maximum depth of each secondary groove (14) is about 8% of the seat diameter ΦA. Container (1) according to any one of claims 12 to 17 characterized in that the radial radius of curvature R6 of the bottom of each secondary groove (14) is between 25% and 55% of the seat diameter ΦA. Container (1) according to claim 18 characterized in that the radial radius of curvature R6 of the bottom of each secondary groove (14) is equal to 31.2% of the seat diameter ΦA. Container (1) according to any one of claims 12 to 19 characterized in that the bottom of each secondary groove (14) has, in cross-section of said secondary groove (14), a curvilinear shape whose radius of curvature is constant or variable from the central pin (12) to its distal end. Container (1) according to claim 20 characterized in that the bottom of each secondary groove (14) has a variable width from the central pin (12) to its distal end, the bottom having a width L3 at the central pin (12) and a width L4 at the distal end of the secondary groove (14). Container (1) according to claim 21 characterized in that the width L3 of the bottom of each secondary groove (14) is between 1 and 7% of the seat diameter ΦA and, preferably, is equal to 3.5% of said seat diameter ΦA. Container (1) according to any one of claims 21 or 22 characterized in that the width L4 of the bottom of each secondary groove (14) is between 30% and 130% of the width L3 and, preferably, is equal to 80% of the width L3. Container (1) according to any one of claims 1 to 23, characterized in that said vault (10) has a height between 11% and 18% of the base diameter ΦA. Container (1) according to any one of claims 1 to 24 characterized in that said central pin (12) has a diameter between 15% and 25% of the seat diameter ΦA and overhangs the vault (10) by a height between 9% and 18% of said seat diameter ΦA, and preferably by a height of 12.6% of said seat diameter ΦA. Container (1) according to any one of claims 24 or 25 characterized in that the vault (10) has a substantially spherical shape of radius R centered on the longitudinal axis of the container (1), said radius R of the vault (10) being between 70% and 120% of the base diameter ΦA. Container (1) according to claim 26 characterized in that said radius R of the vault (10) is equal to 86% of the seat diameter ΦA. Container (1) according to any one of claims 1 to 27 characterized in that the bottom of the central pin (12) is made of a spherical cap whose concavity is oriented towards the seat (8) and whose radius of curvature is between 25% and 75% of the seat diameter ΦA. Container (1) according to claim 28 characterized in that the radius of curvature of the bottom of the central pin (12) is equal to 50% of the seat diameter ΦA. Container (1) according to any one of claims 1 to 29 characterized in that the central pin (12) is composed of at least three consecutive rays from its bottom to the vault (10). Container (1) according to any one of claims 1 to 30 characterized in that the width p of the seat (8) is between 0.5% and 5% of the seat diameter ΦA. Container (1) according to claim 31 characterized in that the width p of the seat (8) is equal to 2.4% of the seat diameter ΦA. Mold base (23) for manufacturing a container (1) from a plastic preform, said mold base (23) being able to be mounted at one end of a mold (20) comprising two walls movable relative to each other and intended to form the body (5) of the container (1), said mold base (23) comprising at least a first annular part intended to form at least in part the heel (7), i.e. the seating surface, a second dome-shaped part intended to come into contact with an amorphous central area of ​​the preform to form the arch (10) of the bottom (6) of the container (1), characterized in that said second part is arranged so as to produce a container (1) comprising a bottom (6) according to any one of claims 1 to 32.

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