Containers with improved petal-shaped bottoms and mold bottoms for producing such containers

Abstract

The present invention relates to a container obtained by blow molding or stretch blow molding from a blank made of plastic material, the container comprising a body consisting of a substantially cylindrical wall, a shoulder at the upper end of the body in the extension of the body, a neck in the extension of the shoulder, and a petal-shaped bottom at the lower end of the body, the bottom having a generally outwardly convex wall from which extend at least three feet formed by protrusions protruding towards the outside of the container, the feet extending from a pellet-shaped central area of ​​the bottom, where the material remains substantially amorphous, towards the periphery of the bottom where it joins the body, the most protruding of the feet The raised portions or tops are coplanar and together form a base on which the container can rest on a flat surface, the base being circular and having a diameter referred to as the base diameter φa, each foot having an end face that extends at a gentle slope from a central region of the base towards the bottom of the foot, the container being notable in that the end face of each foot includes at least two sections: a first so-called central section that extends from the central region of the base towards the top of the foot and has an outwardly facing concave surface, and a second so-called peripheral section that extends from the central section of the foot to the bottom and has an outwardly facing convex surface.

Description

[Technical Field]

[0001] The present invention relates to the production of containers, in particular bottles, obtained by blow molding or stretch blow molding from blanks, also commonly called preforms or intermediate containers, made of plastic material such as polyethylene terephthalate (PET) and / or recycled polyethylene terephthalate (rPET). More particularly, the present invention relates to containers with a petal-shaped bottom and to a mold bottom for producing such containers, which allows for improved distribution of material during the blow molding of the bottom and ultimately improves the mechanical strength of the container bottom. [Background technology]

[0002] In the field of manufacturing containers made from PET, it is well known that the container generally comprises an open neck through which the contents (generally liquid) are introduced, a body that provides the container with its volume, and a bottom that closes the body opposite the neck and forms a base designed to ensure strength and retention of the container when it is placed on a surface.

[0003] Containers designed for carbonated beverages, where the pressure of gases dissolved in the liquid causes great mechanical stresses, are mostly provided with petal-shaped bases that include protruding petal-shaped feet separated by convex wall sections, called troughs or valleys, that extend radially from the central region of the base. The feet are designed to ensure the retention of the container when placed on a surface, and the valleys are designed to absorb the (thermal and mechanical) forces exerted by the container.

[0004] The performance of the petaloid base is measured in terms of its mechanical strength, i.e., its ability to be deformed in a limited or controlled manner, not only during filling but also during storage of the container, which may be carried out for long periods under conditions of extreme temperature and humidity, which are rarely encountered in temperate countries but are common in countries with continental, tropical or desert climates.

[0005] It is desirable to avoid frequent deformations, such as sagging in the central region of the base, since this deformation leads to sensitivity to "stresses", changes in the shape of the foot, and ultimately to a lack of stability of the container. It is also noted that container manufacturers want to meet the demands of retailers without reducing the production rate of said containers, or conversely, at a higher rate if possible.

[0006] In this regard, improved technical solutions have already been proposed which improve the stability over time of the base of containers filled under pressure and stored in a hot and humid atmosphere, without affecting production speed, as is the case in particular in patent application FR 2 897 292.

[0007] French Patent Application Publication No. 2 897 292 describes a mould bottom for a mould for producing containers, in particular bottles, made of a thermoplastic material such as PET by blow moulding or stretch blow moulding, the container having a body and a so-called petal-shaped bottom with a number of feet, which are angularly equidistantly distributed and separated from one another by radial valleys with convexly widening bases, which extend substantially parallel to the axis of the container, the mould bottom having a mould cavity comprising a number of cavities for moulding the bottoms of the containers, which are angularly equidistantly distributed and separated from one another by radial ridges with concavely widening ridges, which extend substantially parallel to the axis of the mould bottom, the bottoms of the cavities being distributed over a substantially circular contour. The mold bottom is characterized in that, when viewed radially on both sides of its lowest point, each cavity is defined on the outside by a curved surface portion that is substantially arc-shaped in a radial cross section, and on the inside by a surface portion of a fractured surface having at least two slopes that intersect the curved surface portion along linear ridges that extend substantially in the circumferential direction, a plane that includes the linear ridges and that is tangent to the curved surface portion is substantially perpendicular to the axis of the mold cavity, and a flat portion adjacent to the curved surface portion has an inclination of approximately 12° to 8° with respect to the tangent plane.

[0008] With this configuration, the two curved portions of the fracture surface are connected by a ridge, which forms a reinforced, approximately circumferential support line for each foot of the container bottom, through which each foot rests on the flat support, and which ridge remains the support point for the foot on the flat support, regardless of any deformation and / or tilting that the foot may undergo under the influence of sagging in the central part of the container bottom.

[0009] This type of mold bottom improves the stability of the bottom of stored containers over time, but does not fully meet the constraints of ideally high mechanical performance, ideally low weight, and ideally simple blowability.

[0010] To remedy these problems, French Patent Application Publication No. 2967975 describes a container made of plastic material comprising a body and a petal-shaped base extending from the body, the base having a generally outwardly convex bottom wall, the bottom having feet formed by protrusions protruding therefrom, the feet being separated in pairs by parts of the bottom wall forming hollow valleys extending radially from the central region of the bottom to the periphery of the bottom, each valley widening from the central region to the periphery and having a concave portion located near the periphery.

[0011] Such containers have the advantage of being highly resistant to deformation. Of particular note is the excellent retention of the central bottom area under hydrostatic pressure, possibly combined with the pressure of dissolved gases in carbonated beverages. This performance is observed not only during filling but also during long-term storage under severe conditions of humidity and pressure.

[0012] However, none of these prior art mold bases and / or containers can provide sufficient mechanical strength for the container when rPET is used in its production. More specifically, the use of rPET complicates the distribution of material during stretch-blow molding and / or blow molding of the container. More specifically, in this case, the amorphous material located in the center of the bottle bottom becomes more difficult to break, increasing the risk of stress generation between the amorphous region and the biaxially oriented region. "Stress" is understood to mean, for example, stress marks in the material, such as cracks or fissures, that weaken the container bottom. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] French Patent Application Publication No. 2897292 [Patent Document 2] French Patent Application Publication No. 2967975 Summary of the Invention [Problem to be solved by the invention]

[0014] One of the aims of the present invention is therefore to remedy these problems by proposing a container and a mould bottom for producing such containers of simple and inexpensive design which achieves good mechanical strength of the container bottom while allowing for higher production rates. [Means for solving the problem]

[0015] To this end, the invention proposes a container obtained by blow molding or stretch-blow molding from a blank made of plastic material, the container comprising a body consisting of a substantially cylindrical wall, a shoulder at the upper end of the body in the extension of the body, a neck in the extension of the shoulder, and a petal-shaped bottom at the lower end of the body, the bottom having a substantially outwardly convex wall from which extend at least three feet formed by protrusions that project towards the outside of the container, the feet extending from a pellet-shaped central area of ​​the bottom, where the material remains substantially amorphous, towards the periphery of the bottom where it joins the body. The container is notable in that the most protruding portions or tops of the feet are coplanar and together form a base on which the container can rest on a flat surface, the base being circular and having a so-called base diameter, each foot having an end face that extends at a gentle slope from a central region of the base towards the bottom of the foot, and the container is notable in that the end face of each foot includes at least two sections: a first so-called central section that extends from the central region of the base towards the top of the foot and has an outwardly facing concave surface, and a second so-called peripheral section that extends from the central section to the bottom of the foot and has an outwardly facing convex surface.

[0016] Such a foot structure, more particularly such a particular structure of a curved shape connecting the foot towards the center, advantageously allows the material to be more easily displaced towards the base during the stretch blow molding manufacturing step, thus allowing a more gradual transition of material from the center towards the base region to be obtained.

[0017] Preferably, the radius of curvature of the second peripheral section is 0.5 to 3 times the diameter of the base.

[0018] Furthermore, the radius of curvature of the central section is preferably 0.3 to 0.6 times the base diameter.

[0019] Additionally, the radius of curvature of the peripheral section and / or the radius of curvature of the central section are not constant.

[0020] Furthermore, the clearance (garde) of the bottom, which corresponds to the height between the central region of the bottom and the top of the foot, i.e., the base surface, is 0.05 to 0.15 times the base diameter.

[0021] Advantageously, each foot has two substantially flat side surfaces that laterally border a valley, said side surfaces of the foot being connected to the valley via concave fillets, the radius of curvature of which is not constant from the central region of each valley to the connecting region.

[0022] Such a foot structure, and more particularly such a particular structure of the concave fillet connecting the sides of two adjacent feet to the valley, advantageously allows material to be more easily displaced towards the base during the stretch blow molding manufacturing step, thus allowing a more gradual transition of material from the center to the base region to be obtained in the valley region.

[0023] Preferably, said radius of curvature of the concave fillet varies from the central region over the length L1 of the valley and is substantially constant from said length L1 to the connection region.

[0024] The length L1 is 0.2 to 0.8 times the base diameter φa, and is preferably equal to 0.5 times the base diameter φa.

[0025] Further, over a portion L2 of the length L1, the concave fillets are separated by a space E of 2 mm or less, the beginning of the length L2 being the central region. The space E may be zero.

[0026] The length L2 from the central region is 0.1 to 0.4 times the base diameter φa, and is preferably equal to 0.3 times the base diameter φa.

[0027] Furthermore, over the remaining length L3 of length L1, the so-called transition length, the radius of curvature of the concave fillet gradually decreases until it reaches the value of the substantially constant radius of curvature of the concave fillet defined for the region extending between the end of length L1 and the connection region.

[0028] A further subject of the invention relates to a mould bottom for a mould for producing containers, in particular bottles, made of a thermoplastic material such as PET by blow moulding or stretch blow moulding, said container comprising a body consisting of a substantially cylindrical wall, a shoulder at the upper end of said body in continuation of said body, a neck in continuation of said shoulder, and a petal-shaped bottom at the lower end of said body, said bottom comprising a generally outwardly convex wall from which extend at least three feet formed by angularly equidistantly distributed protrusions and separated from one another by radial valleys extending approximately parallel to the axis of the container and having convex, curved, radially expanding bases, said mould bottom comprising at least three cavities, said at least three cavities being arranged in a manner such that the bottom of said container is in a convex, curved, radially expanding base ... For molding purposes, the cavities are angularly distributed equidistantly and separated from one another by radial ridges extending substantially parallel to the axis of the mold bottom and having concave radially extending ridges, the bottoms of the cavities being distributed over a substantially circular contour corresponding to the so-called base diameter φa of the container, each cavity having a bottom surface extending at a gentle slope from a central region of the bottom towards the bottom of the cavity, and the mold bottom is notable in that the bottom surface of each cavity comprises at least two sections: a first so-called central section extending from the central region of the mold bottom towards the bottom of the cavity and having a convex surface facing inwards of the mold bottom, and a second so-called peripheral section extending from the central section to the bottom of the cavity and having a concave surface facing inwards of the mold bottom.

[0029] Preferably, the radius of curvature of the second peripheral section is 0.5 to 3 times the base diameter φa.

[0030] Furthermore, the radius of curvature of the central section is preferably 0.3 to 0.6 times the base diameter φa.

[0031] Additionally, the radius of curvature of the peripheral section and / or the radius of curvature of the central section are not constant.

[0032] Furthermore, the bottom clearance, which corresponds to the height between the central region of the mold bottom and the bottom of the cavity, is 0.05 to 0.15 times the base diameter φa.

[0033] Advantageously, the mold bottom has convex fillets on both sides of the ridge connecting the ridges extending on both sides of the ridge, the radius of curvature of the convex fillets not being constant from the central region towards the edge of the central depression.

[0034] Preferably, said radius of curvature of the convex fillet varies from the central region over the length L1 of the ridge and is substantially constant from said length L1 to the edge of the central depression.

[0035] The length L1 is 0.2 to 0.8 times the base diameter φa, and is preferably equal to 0.5 times the base diameter φa.

[0036] Furthermore, over a portion L2 of the length L1 corresponding to the length starting from the central region, the convex fillets are separated by a space E of 2 mm or less. The space E may be zero.

[0037] The length L2 from the central region is 0.1 to 0.4 times the base diameter φa, and is preferably equal to 0.3 times the base diameter φa.

[0038] Furthermore, over the remaining length L3 of length L1, the so-called transition length, the radius of curvature of the convex fillet gradually decreases until it reaches the value of a substantially constant radius of curvature of the convex fillet defined for the region extending between the end of length L1 and the edge of the central depression.

[0039] A final subject of the invention relates to a molding device for producing containers, in particular bottles, from preforms made of a thermoplastic material such as PET by blow molding or stretch blow molding, said container comprising a body consisting of a substantially cylindrical wall, a shoulder at the upper end of said body in continuation of said body, a neck in continuation of said shoulder, and a petal-shaped bottom at the lower end of said body, said bottom comprising a generally outwardly convex wall from which extend at least three feet formed by angularly equidistantly distributed projections which extend approximately parallel to the axis of the container and are separated from one another by radial valleys with convex, curved, radially expanding bases, said molding device comprising at least one mould bottom which can be movably attached to a side wall which defines a cavity with the impression of a portion of the container, said side wall comprising two a mold half, each defining a half-impression of the body of the container, mounted rotatably relative to one another between a so-called open position and a so-called closed position, in which the mold halves are angularly separated from one another and the mold bottom is lowered relative to the mold halves to allow the introduction of the preform and the removal of the molded container, and in the closed position the mold halves are applied to one another, capturing the mold bottoms therebetween, thus forming a cavity and defining the total footprint of the molded container, said mold bottom comprising at least three cavities angularly distributed equidistantly and separated from one another by radial ridges extending substantially parallel to the axis of the mold bottom and having concave radially extending ridges, the bottoms of the cavities being distributed over a substantially circular contour, said apparatus being notable in that the mold bottoms are arranged in accordance with the invention as described above.

[0040] Further advantages and features will become more apparent from the following description of a single variant according to the invention, given as a non-limiting example, with reference to the attached drawings, in which: [Brief explanation of the drawings]

[0041] [Figure 1]1 is a partial perspective view from below of a container with a petal-shaped bottom according to the present invention; FIG. [Figure 2] 2 is a side view of the lower portion of the container having a petal-shaped bottom according to the present invention shown in FIG. 1. [Figure 3] 3 is a view from below of the bottom of the container according to the invention shown in FIGS. 1 and 2; FIG. [Figure 4] 4 is a cross-sectional view of the bottom of FIG. 3 taken along section line IV-IV'. [Figure 5] FIG. 5 is a cross-sectional view of the cross-sectional view shown in FIG. [Figure 6] 10 is a partial perspective view from below of a variant of the bottom of a container having a petal-shaped bottom according to the invention; FIG. [Figure 7] 7 is a side view of the lower part of a variation of the container having a petal-shaped bottom according to the present invention shown in FIG. 6. FIG. [Figure 8] 8 is a view from below of the bottom of the variant of the container according to the invention shown in FIGS. 6 and 7; FIG. [Figure 9] 8 is a schematic cross-sectional view of two adjacent feet of the bottom of the variant of the container according to the invention shown in FIGS. 6 and 7. FIG. [Figure 10] FIG. 2 is a perspective view of the bottom of a mold according to the present invention. [Figure 11] FIG. 11 is a top view of the bottom of the mold according to the present invention shown in FIG. 10. [Figure 12] 12 is a cross-sectional view of the mold bottom of FIG. 11 taken along the section line XII-XII'. DETAILED DESCRIPTION OF THE INVENTION

[0042] In the remainder of the description of the container according to the invention, like reference numerals refer to like elements. The different figures are not necessarily drawn to scale.

[0043] 1 to 3, the container 1 according to the present invention is, for example, a bottle designed to contain gaseous or carbonated beverages. The bottle is manufactured from PET and / or rPET by extrusion blow molding or injection blow molding of the constituent materials. The present invention is preferably applied to containers of this type. However, it is clear that the container 1 can be manufactured from any other thermoplastic material known per se, or from a mixture of various materials, without departing from the scope of the present invention.

[0044] Said container 1 comprises, in the usual way, a body 2 forming a cylindrical wall and extending from a petal-shaped base 3, surmounted by a shoulder, terminating in a neck and terminating in a neck opening threaded or in any other way adapted to receive a cap, the shoulder, neck, neck opening and cap not being shown in FIG. 1.

[0045] The petal-shaped base 3 comprises feet 4 formed by protrusions extending from a substantially hemispherical wall 5 having an outwardly facing convex surface and forming a valley 6 between two adjacent feet 4, the hemispherical wall 5 forming the bottom of the valley 6. The upper end of each foot 4 is connected to the body 2.

[0046] In this particular exemplary embodiment, the petal-shaped base 3 has five lobes forming a foot 4, which are angularly equidistantly distributed and separated from one another by radial valleys 6 that extend substantially parallel to the longitudinal axis of the container 1 and have a convex, curvilinear, radially flaring base. All of the valleys 6 converge towards a so-called central region 7 of the bottom 3, which consists of slightly outwardly protruding circular plates or pellets in which the material remains substantially amorphous. The bottom 3 of the container 1 is connected to the body 2 of the container 1 by a so-called connection region 8, which is substantially cylindrical in revolution.

[0047] Thus, the feet 4 are separated in pairs by portions of the bottom wall 5 called valleys 6, which extend radially in a star shape from a central region formed by a central region 7 to a periphery formed by a connecting region 8. The valleys 6 are outwardly concave in cross section, i.e., in a plane perpendicular to the radial direction. The radius of curvature of the valleys 6 can vary. More specifically, the radius of curvature is preferably small near the central region 7 and relatively large near the connecting region 8.

[0048] Furthermore, the valley 6 has, near the central region 7, an inner portion 9 that is outwardly convex in radial cross section, and, near the connection region 8, an outer portion 10 that is outwardly concave in radial cross section.

[0049] In the example shown in the drawings, the base 3 comprises five feet 4 and five valleys 6 regularly arranged alternately and distributed in a star shape. This number constitutes a good compromise, but this number can be smaller (but not less than 3) or larger (but preferably not more than 7). Furthermore, the most protruding parts or tops 16 of the feet 4 are coplanar and together form a base on which the container 1 can rest on a flat surface, said base being circular and having a so-called base diameter, denoted φa in the remainder of this description, and each foot 4 has an end face 13 that extends at a gentle slope from the central region 7 of the base 3 towards the bottom of said foot 4.

[0050] Each foot 4 has two substantially flat side surfaces 12, each laterally bordering a valley 6. The side surfaces 12 are not vertical (as it would be difficult or even impossible to blow-mold the base 3 in that case) but are inclined and open outward from the valley 6. The side surfaces 12 are connected to the end surface 13 by fillets 14. Each foot 4 is also radially delimited by an outer surface 15 that extends in the extension of the body 2 to the vicinity of the top 16 of the foot 4 and is connected to the top 16 by fillets 17. The outer surface 15 is not cylindrical but is substantially conical about the longitudinal axis of the container 1. Furthermore, in radial cross section, this surface 15 is not straight but is convex with a large radius of curvature. At the periphery of the bottom 3, the surface 15 is connected to the body 2 via a connection region 8 in the form of a fillet.

[0051] Advantageously, the bottom 3 is also provided with a radial groove 18 which extends hollowly inside the container 1 along the valley 6 .

[0052] More specifically, each radial groove 18 extends along the midline of the valley 6 from near the central region 7 to near the connection region 8. In plan view, each groove 18 has a substantially oval shape, with its edges parallel over most of its length and both of its ends flared. In radial cross section, each groove 18 has a flared U-shaped profile. The grooves 18 function to reinforce the base 3. Under the influence of mechanical stresses applied to the container 1 (in particular under the influence of the pressure prevailing in a container filled with carbonated liquid), the grooves 18 tend to migrate by expanding and flattening, which causes the valley 6 to widen and, as a result, causes a verticalization of the foot 4, which counteracts the overall sagging of the base 3.

[0053] Furthermore, each valley 6 widens from a central region 7 to a connecting region 8. This widening is preferably continuous, i.e. the edges of the valleys 6 form angles with each other that are non-zero at every point. In the example shown, the valleys 6 have a tulip-shaped (or bell-shaped) profile in plan view, but this shape is not limiting and the edges of the valleys 6 may also be straight, in which case said valleys 6 have a V-shaped profile.

[0054] Particularly advantageously, said end face 13 of each foot 4 comprises at least two sections 13a, 13b, namely a first so-called central section 13a and a second so-called peripheral section 13b, the first central section 13a extending from the central region 7 of the bottom towards the top 16 of the foot 4 and having an outwardly facing concave surface, and the second peripheral section 13b extending from the central section 13a to the bottom of the foot 4 and having an outwardly facing convex surface.

[0055] Such a foot structure, more particularly such a particular structure in the form of a curve connecting the foot towards the centre, advantageously allows the material to be more easily displaced towards the base during the stretch blow moulding manufacturing step, thus allowing a more gradual transition of material from the centre to the base region to be obtained.

[0056] Preferably, the radius of curvature of the second peripheral section 13b is 0.5 to 3 times the base diameter φa, and the radius of curvature of the first central section 13a is preferably 0.3 to 0.6 times the base diameter φa. In this way, material displacement is optimal during the stretch blow molding step.

[0057] In this particular exemplary embodiment, the radius of curvature of the peripheral section 13b and the radius of curvature of the central section 13a are constant and of different values, although it will be apparent that the radii of curvature of the peripheral section 13b and the central section 13a can be equal without departing from the scope of the present invention.

[0058] It will further be apparent that the radius of curvature of the peripheral section 13b and / or the radius of curvature of the central section 13a may not be constant over the entire length of each section 13a, 13b without departing from the scope of the present invention.

[0059] Furthermore, the bottom clearance, which corresponds to the height between the central region 7 of the bottom 3 and the top 16 of the foot 4, ie, the base surface, is 0.05 to 0.15 times the base diameter φa.

[0060] 6 to 9, according to a modified version of the container bottom according to the present invention, the petal-shaped bottom 3 has, as before, feet 4 formed by protrusions, which extend from substantially hemispherical walls 5 having outwardly facing convex surfaces to form valleys 6 between two adjacent feet 4, the hemispherical walls 5 forming the bottoms of the valleys 6. The upper end of each foot 4 is connected to the body 2.

[0061] As before, the petal-shaped base 3 has five protrusions forming feet 4, angularly distributed at equal distances and separated from one another by radial valleys 6, which extend substantially parallel to the longitudinal axis of the container 1 and have a convex, curvilinear, radially expanding base. All of the valleys 6 converge towards a so-called central region 7 of the base 3, which consists of slightly outwardly projecting circular plates or pellets in which the material remains substantially amorphous. The base 3 of the container 1 is connected to the body 2 of the container 1 by a so-called connection region 8, which is substantially cylindrical in revolution.

[0062] Thus, the feet 4 are separated in pairs by portions of the bottom wall 5 called valleys 6, which extend radially in a star shape from a central region formed by a central region 7 to a periphery formed by a connecting region 8. The valleys 6 are outwardly concave in cross section, i.e., in a plane perpendicular to the radial direction. The radius of curvature of the valleys 6 can vary. More specifically, the radius of curvature is preferably small near the central region 7 and relatively large near the connecting region 8.

[0063] Furthermore, the valley 6 has, near the central region 7, an inner portion 9 that is outwardly convex in radial cross section, and, near the connection region 8, an outer portion 10 that is outwardly concave in radial cross section.

[0064] In the example shown in the drawings, the base 3 comprises five feet 4 and five valleys 6 regularly arranged alternately and distributed in a star shape. Furthermore, the most protruding parts or peaks 16 of the feet 4 are coplanar and together form a base on which the container 1 can rest on a flat surface, said base being circular and having a so-called base diameter denoted in the remainder of the specification by φa, and each foot 4 has an end face 13 extending at a gentle slope from a central region 7 of the base 3 towards the bottom of said foot 4.

[0065] Each foot 4 has two substantially flat side surfaces 12, each laterally bordering a valley 6. The side surfaces 12 are not vertical (as it would be difficult or even impossible to blow-mold the base 3 in that case) but are inclined and open outward from the valley 6. The side surfaces 12 are connected to the end surface 13 by fillets 14. Each foot 4 is also radially delimited by an outer surface 15 that extends in the extension of the body 2 to the vicinity of the top 16 of the foot 4 and is connected to the top 16 by fillets 17. The outer surface 15 is not cylindrical but is substantially conical about the longitudinal axis of the container 1. Furthermore, in radial cross section, this surface 15 is not straight but is convex with a large radius of curvature. At the periphery of the bottom 3, the surface 15 is connected to the body 2 via a connection region 8 in the form of a fillet.

[0066] Advantageously, the bottom 3 is also provided with a radial groove 18 which extends hollowly in the bottom 3 along the valley 6 into the inside of the container 1 .

[0067] More specifically, each radial groove 18 extends along the midline of the valley 6 from the vicinity of the central region 7 to the vicinity of the connection region 8. In plan view, each groove 18 has a substantially oval shape, with its edges parallel over most of its length and both of its ends flared. In radial cross section, each groove 18 has a flared U-shaped profile. The grooves 18 serve to reinforce the base 3. Under the influence of mechanical stresses applied to the container 1 (in particular under the influence of the pressure prevailing in a container filled with carbonated liquid), the grooves 18 tend to move by expanding and flattening, which causes the valleys 6 to widen and, consequently, verticalization of the feet 4, which counteracts the overall sagging of the base 3.

[0068] Furthermore, each valley 6 widens from a central region 7 to a connecting region 8. This widening is preferably continuous, i.e. the edges of the valleys 6 form angles with each other that are non-zero at every point. In the example shown, the valleys 6 have a tulip-shaped (or bell-shaped) profile in plan view, but this shape is not limiting and the edges of the valleys 6 may also be straight, in which case said valleys 6 have a V-shaped profile.

[0069] Particularly advantageously, said end face 13 of each foot 4 comprises at least two sections 13a, 13b, namely a first so-called central section 13a and a second so-called peripheral section 13b, the first central section 13a extending from the central region 7 of the bottom towards the top 16 of the foot 4 and having an outwardly facing concave surface, and the second peripheral section 13b extending from the central section 13a to the bottom of the foot 4 and having an outwardly facing convex surface.

[0070] Preferably, the radius of curvature of the second peripheral section 13b is 0.5 to 3 times the base diameter φa, and the radius of curvature of the first central section 13a is preferably 0.3 to 0.6 times the base diameter φa. In this way, material displacement is optimal during the stretch blow molding step.

[0071] In this particular embodiment, the radius of curvature of peripheral section 13b and the radius of curvature of central section 13a are substantially constant and are different values, although it will be apparent that the radii of curvature of peripheral section 13b and central section 13a can be equal without departing from the scope of the present invention.

[0072] It will further be apparent that the radius of curvature of the peripheral section 13b and / or the radius of curvature of the central section 13a may not be constant over the entire length of each section 13a, 13b without departing from the scope of the present invention.

[0073] Furthermore, the bottom clearance, which corresponds to the height between the central region 7 of the bottom 3 and the top 16 of the foot 4, ie, the base surface, is 0.05 to 0.15 times the base diameter φa.

[0074] This variant is distinguished from the one described above by the fact that the side surfaces 12 of the foot portions 4 are connected to the valley portions 6 by concave fillets 19, and the radii of curvature, indicated as R1a and R1b in FIG. 9, are not constant from the central region 7 to the connecting region 8 of each valley portion 6. More specifically, the radius of curvature of the concave fillets 19 varies from the central region 7 to the length L1 of the valley portion 6, but is substantially constant from the length L1 to the connecting region 8. The length L1 is 0.2 to 0.8 times the base diameter φa, and preferably equal to 0.5 times the base diameter φa. Furthermore, the length L1 can be decomposed into two lengths, L2 and L3, i.e., L1 = L2 + L3. The length L2 corresponds to the length starting from the central region 7, where the space E between the concave fillets 19 of two adjacent foot portions 4 separated by the valley portion 6 is smallest. Preferably, over this length L2, the space E between the concave fillets 19 of two adjacent legs 4 separated by a valley 6 is equal to or less than 2 mm. Note that the space E can be zero, i.e., 0. In this case, the concave fillets 19 of two adjacent legs 4 are connected at a distance L2 from the central region 7. The length L2 from the central region 7 is 0.1 to 0.4 times the base diameter φa, and preferably equal to 0.3 times the base diameter φa. Over the length L3, the so-called transition length, the radius of curvature of the concave fillet 19 gradually decreases until it reaches the value of the constant radius of curvature of the concave fillet 19 defined for the region extending between the end of the length L1 and the connection region 8.

[0075] It should be noted that such a foot structure, and more particularly such a particular structure of the concave fillet 19 connecting two adjacent foot sides 12 to the valley 6, advantageously allows the material to be more easily displaced towards the base during the stretch blow molding manufacturing step, and thus allows a more gradual transition of material from the center to the base region to be obtained in the valley 6 region.

[0076] Referring now to Figures 10 to 12, there is shown a mould bottom 100 designed to equip a mould for producing a container 1, in particular a bottle, according to the invention made of a thermoplastic material, more particularly made of rPET and / or PET, by blow moulding or stretch blow moulding, as described above with reference to Figures 1 to 5.

[0077] The mold bottom 100 is provided with a mold cavity 101 for forming the bottom 3 of the container 1, which comprises a number of cavities 102, generally 3 to 7, in practice 4 to 6 (5 in the example shown in Figures 1 to 5), equal to the number of feet 4 of the bottom 3 of the container 1, which are angularly equidistantly distributed (in this example, at an angular interval of 72° from one another), extending substantially parallel to the axis of the mold bottom 100 (which is also the axis of the mold cavity C), and separated from one another by radial ridges 103 (i.e., protrusions extending substantially radially from the mold cavity C, which lead to the formation of the valleys 6 in the base 3 of the formed container 1). Each ridge 103 has a convex, curvilinear radial extent and has an arc-shaped ridge 104 starting from the edge of a central depression 105. The bottom 106 of the cavity 101 is distributed over a substantially circular contour 107 with a given base diameter φa, which corresponds to the base diameter φa of the bottom 3 of the container 1. The center of the mold cavity 101 comprises a protruding central region 108, in which a circular cavity 109 of reduced depth is hollowed out for forming the pellets of the aforementioned central region 7 of the bottom 3 of the container 1. According to the invention, each cavity 102 has a bottom surface 110 that extends with a gentle slope from the central region 108 of the mold bottom 100 to the bottom of the cavity 102. When viewed radially on both sides of its lowest point, each cavity 102 is delimited on the outside by curved surface portions 111 that are substantially arc-shaped in radial cross section, and on the inside by surface portions 112 with a so-called connecting curve.

[0078] In a preferred embodiment shown in Figures 10 to 12, the bottom surface 110 of each cavity 102 comprises at least two sections 110a, 110b, namely a so-called first central section 110a and a so-called peripheral section 110b, the first central section 110a extending from the central region 108 of the mold bottom 100 towards the bottom of the cavity 102 and having a convex surface facing inwards of the mold bottom 100, and the second peripheral section 110b extending from the central section 110a to the bottom of the cavity 102 and having a concave surface facing inwards of the mold bottom 100.

[0079] As with the container 1 described above, the radius of curvature of the second peripheral section 110b is preferably 0.5 to 3 times the base diameter φa, and the radius of curvature of the first central section 110a is preferably 0.3 to 0.6 times the base diameter φa. In this way, material displacement is optimal during the stretch blow molding step.

[0080] In this particular exemplary embodiment, the radius of curvature of the peripheral section 110b and the radius of curvature of the central section 110a are constant and of different values, although it will be apparent that the radii of curvature of the peripheral section 110b and the central section 110a may also be equal without departing from the scope of the present invention.

[0081] It will further be apparent that the radius of curvature of the peripheral section 110b and / or the radius of curvature of the central section 110a may not be constant over the entire length of each section 110a, 110b without departing from the scope of the present invention.

[0082] Furthermore, the bottom clearance, which corresponds to the height between the central region 108 of the mold bottom 100 and the bottom of the cavity 102, is 0.05 to 0.15 times the base diameter φa.

[0083] According to one variant according to the invention not shown in the figures, the mold bottom 100 has convex fillets 119 on both sides of the ridge 104 connecting the ridges 103 extending on both sides of the ridge, the radius of curvature of the convex fillets not being constant from the central region 108 towards the edge of the central depression 105.

[0084] More specifically, the radius of curvature of the convex fillet 119 varies from the central region 108 along the edge 104 over a length L1, but is substantially constant from the length L1 to the edge of the central depression 105. The length L1 is 0.2 to 0.8 times the base diameter φa, and preferably equal to 0.5 times the base diameter φa. Furthermore, the length L1 can be decomposed into two lengths, L2 and L3, i.e., L1 = L2 + L3. The length L2 corresponds to the length starting from the central region 108 where the spacing E between the convex fillets 119 on the same edge 104 is smallest. Preferably, over this length L2, the spacing E between the convex fillets 119 on the same edge 104 is 2 mm or less. Note that the spacing E can be zero, i.e., 0. In this case, the convex fillets 119 are connected at a distance L2 from the central region 108. The length L2 from the central region 108 is 0.1 to 0.4 times the base diameter φa, preferably equal to 0.3 times the base diameter φa. Over the length L3, the so-called transition length, the radius of curvature of the convex fillet 119 gradually decreases until it reaches the value of the constant radius of curvature of the convex fillet 119 defined for the region extending between the end of the length L1 and the edge of the central recess 105.

[0085] A final subject of the invention, not shown, relates to a molding device for producing containers such as those described above by blow molding or stretch blow molding.

[0086] The molding apparatus comprises at least one mold bottom movably mounted in the usual manner to a sidewall defining a cavity having an impression of a portion of the container, the sidewalls each defining a half impression of the container body, and two mold halves rotatably mounted relative to each other between a so-called open position in which the mold halves are angularly separated from each other and the mold bottom is lowered relative to the mold halves to allow the introduction of a preform and removal of the molded container, and a so-called closed position in which the mold halves are applied relative to each other, capturing the mold bottoms therebetween and thus forming the cavity and defining the total footprint of the molded container, the mold bottom comprising at least three cavities, angularly distributed equidistantly and separated from each other by radial ridges having concave radially extending ridges extending substantially parallel to the axis of the mold bottom, the cavity bottoms being distributed over a substantially circular contour. The molding apparatus is distinguished by the fact that the mold bottoms are arranged as described above with reference to Figures 6 to 8.

[0087] Finally, it is clear that the examples provided are only specific illustrations and are in no way limiting with regard to the field of application of the invention.

Claims

1. Container obtained by blow molding or stretch blow molding from a blank made of plastic material, a body having a substantially cylindrical wall; a shoulder at the upper end of the body, the shoulder being an extension of the body; A neck that is an extension of the shoulders, a petal-shaped base at the lower end of the body; the bottom portion has a generally outwardly convex wall; at least three feet formed by protrusions extending from the wall toward the exterior of the container; the feet extend from a pellet-shaped central region of the base, where the material remains substantially amorphous, to a peripheral edge of the base where the base connects to the body; the most protruding portions or tops of the feet are coplanar and together form a base upon which the container can rest on a flat surface; The base is circular and has a so-called base diameter φa, 1. A container, wherein each foot has an end face that extends at a gentle slope from a central region of the base toward the bottom of the foot, a container characterized in that the end surface of each foot comprises at least two sections: a first so-called central section extending from a central region of the bottom towards the top of the foot and having an outwardly facing concave surface, and a second so-called peripheral section extending from the central section to the bottom of the foot and having an outwardly facing convex surface.

2. 2. The container of claim 1, wherein the radius of curvature of the second peripheral section is 0.5 to 3 times the base diameter φa.

3. 3. The container according to claim 1, wherein the radius of curvature of the central section is 0.3 to 0.6 times the base diameter φa.

4. Container according to any one of claims 1 to 3, characterized in that the radius of curvature of the peripheral section is not constant.

5. Container according to any one of claims 1 to 4, characterized in that the radius of curvature of the central section is not constant.

6. A container according to any one of claims 1 to 5, characterized in that the bottom clearance, corresponding to the height between the central region of the bottom and the top of the foot, i.e., the base surface, is 0.05 to 0.15 times the base diameter φa.

7. 7. The container according to claim 1, wherein each foot has two substantially flat side surfaces that laterally border the valleys, the side surfaces of the foot being connected to the valleys via concave fillets, the radius of curvature of which is not constant from the central region of each valley to the connecting region.

8. The radius of curvature of the concave fillet is the length L of the valley from the central region. １ and the length L １ 8. The container of claim 7, wherein the thickness is substantially constant from the first region to the connecting region.

9. The length L １ Container according to claim 8, characterized in that is between 0.2 and 0.8 times the base diameter φa, preferably equal to 0.5 times said base diameter φa.

10. Length L １ Part L ２ The concave fillets are separated by spaces E of 2 mm or less over a length L ２ 10. The container according to claim 8 or 9, characterized in that the starting point of the first and second flanks is in the central region.

11. Container according to claim 10, characterized in that the space E is zero.

12. The length L from the central region 7 ２ Container according to claim 10 or 11, characterized in that is between 0.1 and 0.4 times the base diameter φa, preferably equal to 0.3 times said base diameter φa.

13. Length L １ The remaining length L ３ , the radius of curvature of the concave fillet over the so-called transition length is １ Container according to any one of claims 10 to 12, characterized in that the radius of curvature of the concave fillet defined for the region extending between the end of the container and the connection region gradually decreases until it reaches a value of a substantially constant radius of curvature.

14. A mould bottom for a mould for producing containers, in particular bottles, made of a thermoplastic material such as PET by blow moulding or stretch blow moulding, The container comprises a body having a substantially cylindrical wall, a shoulder at an upper end of the body in the extension of the body, a neck in the extension of the shoulder, and a petal-shaped bottom at a lower end of the body, the bottom portion having a generally outwardly convex wall; at least three feet extend from the wall, the at least three feet being formed by angularly equidistantly distributed projections, the projections extending generally parallel to the axis of the container and separated from one another by radial valleys having convex, curved, radially expanding bases; the mold bottom comprises at least three cavities, angularly equidistantly distributed for forming the bottom of a container, and separated from one another by radial ridges extending substantially parallel to the axis of the mold bottom and having concave radially extending ridges; the bottom of said cavity is distributed over a substantially circular contour corresponding to the so-called base diameter φa of the container, Each cavity has a bottom surface that extends at a gentle slope from a central region of the bottom to the bottom of the cavity, A mold bottom, characterized in that the bottom surface of each cavity comprises at least two sections: a first so-called central section extending from a central region of the mold bottom in the direction of the bottom of the cavity and having a convex surface facing inward of the mold bottom, and a second so-called peripheral section extending from the central section to the bottom of the cavity and having a concave surface facing inward of the mold bottom.

15. 15. The mold base according to claim 14, wherein the radius of curvature of the second peripheral section is 0.5 to 3 times the base diameter φa.

16. 16. A mold base according to claim 14, wherein the radius of curvature of the central section is 0.3 to 0.6 times the base diameter φa.

17. 17. A mould base according to any one of claims 4 to 16, characterized in that the radius of curvature of the peripheral section is not constant.

18. 18. Mold base according to any one of claims 14 to 17, characterized in that the radius of curvature of the central section is not constant.

19. 19. The mold bottom according to any one of claims 14 to 18, characterized in that the bottom clearance corresponding to the height between the central region of the mold bottom and the bottom of the cavity is 0.05 to 0.15 times the base diameter φa.

20. 20. A mold bottom according to any one of claims 14 to 19, characterized in that it is provided on both sides of the ridge with convex fillets connecting the ridges extending on both sides of the ridge, the radius of curvature of the convex fillets not being constant from the central region towards the edge of the central depression.

21. The radius of curvature of the convex fillet is the length L of the ridge from the central region. １ and the length L １ 21. A mold base according to claim 20, characterized in that the thickness of the mold base is substantially constant from the edge of the central recess to the edge of the central recess.

22. The length L １ is 0.2 to 0.8 times the base diameter φa, preferably equal to 0.5 times said base diameter φa.

23. The length L １ The part L corresponding to the length of the central region ２ 23. A mold base according to claim 21 or 22, characterized in that over the entire length, the convex fillets are separated by spaces E of 2 mm or less.

24. 24. The mold base according to claim 23, wherein the space E is zero.

25. The length L from the central region ２ Mold bottom according to claim 23 or 24, characterized in that is between 0.1 and 0.4 times the base diameter φa, preferably equal to 0.3 times said base diameter φa.

26. Length L １ The remaining length L ３ , over the so-called transition length, the radius of curvature of the convex fillet is the length L １ 26. A mold bottom according to any one of claims 23 to 25, characterized in that the radius of curvature of the convex fillet defined for the area extending between the end of the mold bottom and the edge of the central depression gradually decreases until it reaches a substantially constant value.

27. 1. A molding apparatus for producing containers, in particular bottles, from preforms made of a thermoplastic material such as PET by blow molding or stretch blow molding, comprising: The container comprises a body having a substantially cylindrical wall, a shoulder at an upper end of the body in the extension of the body, a neck in the extension of the shoulder, and a petal-shaped bottom at a lower end of the body, the bottom portion having a generally outwardly convex wall; at least three feet extend from the wall, the at least three feet being formed by angularly equidistantly distributed projections that extend generally parallel to the axis of the container and are separated from one another by radial valleys having convex, curved, radially expanding bases; the molding device comprising at least one mold bottom movably mountable to a sidewall defining a cavity having an indicia of a portion of the container; said side wall comprises two mould halves, each defining a half-imprint of the body of the container, and rotatably mounted relative to one another between a so-called open position and a so-called closed position, in which the mould halves are angularly separated from one another and the mould bottom is lowered relative to the mould halves to allow the introduction of the preform and the removal of the moulded container, and in which in the closed position the mould halves are applied relative to one another, capturing the mould bottom between them, thus forming a cavity and defining the total footprint of the moulded container; the mold bottom includes at least three cavities, the at least three cavities being angularly equidistantly distributed and separated from one another by radial ridges extending substantially parallel to the axis of the mold bottom and having concave radially extending ridges; 27. A molding apparatus, wherein the cavity bottoms are distributed over a substantially circular contour, characterized in that the mold bottoms are arranged as claimed in any one of claims 14 to 26.

Images