EP2133277A1 - Container, in particular a bottle, made from thermoplastic material equipped with a reinforced bottom - Google Patents

Abstract

The container has a body extending between a neck and a base (3) that has an annular zone (5) surrounding a bottom of a concave arch (4) and forming a plane seat. The base has clamp zones (11) separated from each other and extending a bottom of the body radially in a direction of a central axis of the base, where the clamp zones project offset outward relative to the arch. Radial grooves (12) are radially defined between the clamp zones and have a bottom (13) formed by radial sections (4a) of the arch. The grooves have a radially variable depth maximum in line with the annular zone.

Description

• · une voûte concave à concavité tournée vers l'extérieur du récipient,
• · un dôme en saillie vers l'intérieur du récipient et à concavité tournée vers l'extérieur, s'ouvrant au centre de ladite voûte,
• · une zone annulaire entourant la base de ladite voûte et formant une assise sensiblement plane par laquelle ledit fond peut reposer de façon stable sur un support plan, et
• · des nervures en forme de gorges ouvertes vers l'extérieur, d'étendue sensiblement radiale traversant ladite zone annulaire formant une assise et remontant sur la paroi de raccordement avec la paroi du corps.

The present invention relates to improvements made to containers, in particular to bottles, made of thermoplastic material such as PET, having a body extending between, above, a neck and, below, a bottom capable of withstanding without significant deformation the hydrostatic pressure due to to the increased liquid column with an overpressure not exceeding about 2 x 10 ⁵ Pa, said bottom comprising:

• · A concave concavity vault turned towards the outside of the container,
• A dome protruding inwardly from the container and concavity facing outwards, opening at the center of said vault,
• An annular zone surrounding the base of said vault and forming a substantially plane base by which said base can rest stably on a plane support, and
• Ribs in the form of grooves open towards the outside, of substantially radial extent passing through said annular zone forming a seat and going up on the connecting wall with the wall of the body.

Containers intended to contain a flat liquid (for example bottles intended to contain table water) are, in most cases, provided with a domed bottom generally spherical cap with concavity facing outwards and of relatively low height. Such bottoms are often provided with substantially radially radially extending ribs which are distributed around a central recess, said ribs being able to present various conformations and capable of possibly overflow on the bottom of the body wall to strengthen the seat (peripheral area by which the bottom rests on a support). The height of funds of this kind, including central recess, is typically of the order of 10 mm, and can be up to 15 mm.

Such bottoms are shaped to support without deformation the column of flat liquid which overcomes them. But they do not have sufficient strength to withstand additional stress, which may for example be due to an internal pressure, even low value.

However, it is known, when packaging certain easily oxidizable flat liquids (for example oil, fruit juice), to pour a small liquid quantity (for example a drop) of an inert substance with rapid vaporization (for example generally the nitrogen) on the surface of the flat liquid at the end of the filling phase of the container in order to evacuate the air (and therefore the oxygen contained therein) from the free volume surmounting the liquid surface immediately before capping of the container (so-called "inerting" or "nitrogenous" operation) or to improve the pressurization of the container in the case of weakly carbonated liquids. This small quantity of inert substance finishes to vaporize once the capping is complete, so that there remains in the closed container of the inerting gas under a low residual pressure of less than 2 × 10 ⁵ Pa, typically of the order of 1 × 10 ⁵ Pa, or of the order of 0.5x10 ⁵ Pa.

The slightly curved bottoms traditionally provided for containers for flat liquids are not able to withstand, without deformation, a pressure as low as that caused by the inerting process.

It is known, therefore, for containers whose contents must undergo a process of inerting, to equip them funds improved in terms of resistance so that they do not deform under the action of the internal pressure.

A reinforced fund of this type that is currently in current use is illustrated in Figures 1A to 1D attached drawings. The Figure 1A is a side view of the lower part of a container 1 (here a bottle of generally cylindrical shape of revolution) of thermoplastic material such as PET, having a body 2 extending between, above, a neck (not visible ) and, bottom, a bottom 3. The bottom 3 is shown, alone, at the Figure 1B in view from below, at the figure 1C in diametrical section along line IC-IC of the Figure 1B , and at figure 1D in perspective from below.

The bottom 3 comprises a vault 4 of generally domed shape with a concavity turned towards the outside of the container 1 and it has an annular zone 5 surrounding the arch 4 and forming a substantially planar base by which said bottom 3 can rest stably on a plane support. In its central part, the vault 4 opens on a domed dome 6 also concavity facing outwardly, said dome thus being set back towards the inside of the container with respect to the vault. Outside the annular zone forming a seat, the bottom 3 has a wall 8, in return, also called wall 8 connecting with the wall 9 of the body 2 of the container.

Several main ribs 7 open towards the outside, in the general shape of gutters with substantially parallel edges and of substantially constant depth, extend radially in a star shape from the wall 8 in return from the bottom 3 to the dome 6 in which they end, crossing the annular zone 5 forming a seat and the roof 4; in the illustrated example, the main ribs 7 are odd, here equal to five. To improve the mechanical strength of the bottom, secondary ribs 10 are added, which may have substantially the same conformation as the main ribs 7, which are interposed between the main ribs 7, but extend radially in a star shape from the wall 8. back from the bottom 3 only to the middle of the vault 4, crossing the annular zone 5 forming a seat.

It will be noted that all the ribs, both the main ribs 7 and the secondary ribs 10, are hollowed out in the roof 4, which has a smooth annular conformation only cut by the ribs as it is clearly visible on the ribs. Figures 1A to 1D .

However, the manufacturers of thermoplastic containers such as PET permanently seek a lighter containers, which results in among other things by lightening the bottoms of the containers. As a result, container bottoms having forms that were satisfactory a few years ago can no longer be suitable because of the substantial reduction in the quantity of material used.

Thus it proved to experience that a reinforced bottom arranged as explained above could no longer be satisfactory, in its lightened version, even for overpressures of only about 1x10 ⁵ Pa.

However, the distribution of drops of inerting liquid requires, to be precise, a dosing equipment which is relatively expensive and which producers avoid using. In these conditions, the drops of inerting liquid are formed more or less empirically and their volume can vary very significantly, in practice between half and twice the theoretical value desirable. As a result, the overpressure generated inside the container can substantially exceed the value of about 1x10 ⁵ Pa desired and can reach up to 2x10 ⁵ Pa. The abovementioned funds, in their lightened version, are therefore not able to to support such an overpressure without collapsing.

According to the document FR 2,883,550 a container with a reinforced bottom which is intended for the same application is also known. However, it is again a container designed to be manufactured with a significant amount of thermoplastic material and which does not provide the light version that manufacturers currently require.

Admittedly, it is known, in the case of carbonated liquids (for example at a pressure of the order of 3 to 4 × 10 ⁵ Pa or even up to 10 × 10 ⁵ Pa), to design containers whose bottom has a much greater curvature. pronounced (so-called "champagne bottoms" or the like) able to withstand relatively high pressures without deformation. However, such funds require an increased amount of thermoplastic material both because of their greater height than because of increased wall thickness at least locally especially in the annular zone forming a seat. Containers provided with such funds are therefore more expensive and their correct conformation during molding is more delicate. It is therefore not desirable to use funds of this type to equip the containers subjected to an inerting operation, and this especially as they are shaped to withstand pressures much higher than those generated by the inerting operation: their high strength and the additional cost associated with them appear excessive for the intended application.

It is in this context that the invention aims to provide an improved convex bottom conformation for clean containers to be filled with flat and closed liquids in the presence of a relatively low pressure in principle of the order of 1x10 ⁵ Pa and in practice not exceeding approximately 2 × 10 ⁵ Pa, requiring only a minimum of thermoplastic material, easy to conform correctly under the usual conditions of blow molding or stretch-blow molding of containers intended for flat liquids, and having a height substantially of the same order of magnitude as that of traditional container bottoms for flat liquids.

• des zones séparées les unes des autres en forme de griffes qui prolongent le bas du corps radialement en direction du centre du fond et qui sont décalées en saillie externe par rapport à ladite voûte, et
• des gorges radiales délimitées entre lesdites zones en forme de griffes, gorges dont le fond est formé par ladite voûte et qui possèdent une profondeur radialement variable qui est maximale approximativement au droit de ladite zone annulaire formant une assise.

For these purposes, a container, especially a bottle, of thermoplastic material such as PET arranged as mentioned in the preamble is characterized in that said bottom comprises:

• zones separated from each other in the form of claws which extend the bottom of the body radially towards the center of the bottom and which are offset in external projection with respect to said vault, and
• radial grooves defined between said claw-shaped zones, grooves whose bottom is formed by said arch and which have a radially variable depth which is approximately approximately to the right of said annular zone forming a seat.

With this arrangement, a bottom is formed in which the reinforcing structure formed by the claw-shaped zones is detached on the roof and, occupying a most of the surface of the vault stiffens it much more effectively than could the current fund veins.

Preferably, it is expected that the radial ends of said claw-shaped areas are spaced from the edge of said dome, so that there remains an integral annular area of the vault around the dome. Thus, a three-level structure is created, namely the central dome, which represents the deepest level (seen from the outside), the vault that surrounds the dome, and extends in a star to form the bottoms of the gorge. which forms an intermediate level, and finally the claw-shaped areas which form an outermost higher level.

This structure leaves many freedoms of practical realization. Thus, the dome can be bulged. The vault can also be curved, for example in a spherical zone, or else be shaped as a truncated cone.

In practice, it can advantageously be provided that said annular zone forming a seat has a diameter that is between about 70% and 90% of the diameter of the body, and that said arch has a height that is between about 10% and 25% of the diameter of the body. diameter of the annular zone forming a seat.

It may also be interesting that the bottom has a height that is greater than about 15% of the diameter of the annular zone forming a seat.

Similarly, it can also be interesting that the height of the dome is between about 10% and 50% of the height of the vault.

Thus, thanks to the arrangements according to the invention, it is possible to design a thermoplastic container such as PET which is capable of to withstand, without deformation, inerting pressures which may incidentally reach up to about 2 x 10 ⁵ Pa, while being produced with a lesser amount of material. For the sake of clarity, a container of 1.51 PET arranged according to the invention can be made with a weight of thermoplastic material of the order of 22 gr, while the weight of containers of equivalent volume PET conventional type and according to the document FR 2,883,550 mentioned above was, only three years ago, of the order of 26 to 27 gr (ie a reduction of about 15% of the weight of PET used per container).

• la figure 1A est une vue de côté de la partie inférieure d'un récipient (ici une bouteille de forme générale sensiblement cylindrique de révolution) en matière thermoplastique telle que du PET agencé selon l'état de la technique ;
• les figures 1B à 1D sont des vues respectivement en vue de dessous, en coupe diamétrale selon la ligne IC-IC de la figure 1B, et en perspective par-dessous, du fond seul du récipient montré à la figure 1A ;
• les figures 2A à 2D sont des vues respectivement en vue de côté, en vue de dessous, en coupe diamétrale selon la ligne IIC-IIC de la figure 2B, et en perspective par-dessous, d'un fond agencé selon l'invention ; et
• les figures 3A et 3B sont des vues, respectivement en coupe diamétrale et en perspective par-dessous (correspondant respectivement aux vues 2C et 2D ci-dessus), d'une variante de réalisation d'un fond agencé selon l'invention.

The invention will be better understood on reading the following detailed description of certain embodiments given solely by way of non-limiting examples. In this description, reference is made to the accompanying drawings in which:

• the Figure 1A is a side view of the lower part of a container (in this case a bottle of generally cylindrical shape of revolution) of thermoplastic material such as PET arranged according to the state of the art;
• the Figures 1B to 1D are views respectively from below, in diametral section along the line IC-IC of the Figure 1B , and in perspective from below, of the sole bottom of the container shown in the Figure 1A ;
• the Figures 2A to 2D are views respectively in side view, in bottom view, in diametral section along the line IIC-IIC of the Figure 2B and in perspective from below, a bottom arranged according to the invention; and
• the Figures 3A and 3B are views, respectively in diametral section and in perspective from below (corresponding respectively to views 2C and 2D above), an alternative embodiment of a bottom arranged according to the invention.

In the description that follows, the same numerical references as those used above will be retained with reference to the Figures 1A to 1D to designate identical elements or parts.

• une voûte 4 concave à concavité tournée vers l'extérieur du récipient ;
• un dôme 6 en saillie vers l'intérieur du récipient et à concavité tournée vers l'extérieur, s'ouvrant au centre de ladite voûte 4 ;
• une zone 5 annulaire entourant la base de ladite voûte 4, au voisinage mais en retrait de la périphérie du fond 3, et formant une assise sensiblement plane par laquelle ledit fond 3 peut reposer de façon stable sur un support plan ; et
• des nervures en forme de gorges ouvertes vers l'extérieur, d'étendue sensiblement radiale traversant ladite zone 5 annulaire formant une assise et remontant sur la paroi 8 de raccordement avec la paroi 9 du corps.

Referring first to Figures 2A to 2D , the container 1, here a bottle of substantially cylindrical general shape of revolution, of thermoplastic material such as PET, has a bottom 3 which comprises:

• a concave arch 4 concavity turned towards the outside of the container;
• a dome 6 projecting towards the inside of the container and concavity facing outwards, opening at the center of said vault 4;
• an annular zone 5 surrounding the base of said arch 4, in the vicinity but set back from the periphery of the base 3, and forming a substantially flat base by which said base 3 can rest stably on a plane support; and
• ribs in the form of grooves open towards the outside, of substantially radial extent passing through said annular zone forming a seat and going up on the wall 8 of connection with the wall 9 of the body.

According to the invention, the bottom 3 has zones 11 in the form of claws, separated from each other, which extend the bottom of the body radially toward the center of the bottom and which are offset projecting from said outer arch 4 In other words, the zones 11 in the form of claws are presented as curvilinear plates surmounting the level of the vault 4 while accompanying the radial shape of it, as seen better in the Figure 2B and especially at the 2D figure .

The zones 11 in the form of claws delimit between them radial grooves 12, grooves whose bottom 13 is formed by radial sections 4a of said arch 4. In other words, while the main ribs 7 of the current bottoms are embedded in the roof 4 as it is clear to the Figures 1A to 1D , the grooves 12 of the bottom arranged according to the invention are formed above the roof 4, in elevation with respect thereto.

In addition, the grooves 12 have a depth which is variable in the radial direction. The inversion of the curvature at 16 of the bottom 13 of the grooves 12 is located approximately vertically above the annular zone forming a seat, as visible in FIG. Figure 2C . It is at this point that the depth p of the grooves 12 is maximum, so that the reinforcement effect is maximum at the level of the seat, which ensures the maintenance of the shape, and therefore of the flatness of the seat. this. The depth of the grooves 12 decreases progressively on both sides until it vanishes at the outer and inner ends of the grooves, as can be seen more clearly on the Figures 2A , 2C and 2D .

Note that in the example shown in Figures 2A to 2D , the radial ends 14, closest to the central axis X of the bottom, said zones 11 in the form of claws remain spaced from the edge 15 of the dome 6 so that the dome 6 is surrounded by an annular fringe 4b of the vault 4 which is connected to the aforesaid radial portions 4a forming the bottoms 13 of the grooves 12, the visible parts of the arch 4 thus having the appearance of a star-shaped structure with radiating branches as seen better on the Figures 2B and 2D .

It should also be noted that in the example illustrated in Figures 2A to 2D , the arch 4 is curved, and here is more specifically curved approximately in the shape of a spherical zone, although other convex conformations are perfectly conceivable.

As far as the geometrical conformation of the bottom 3 is concerned, it is advantageous (see Figure 2C ) that the annular area forming a seat has a diameter B which is between about 70% and 90% of the diameter A of the body 2 of the container 1, and that the roof 4 has a height C which is between about 10% and 25% of the diameter B of the annular zone 5 forming a seat.

In addition, it may also be desirable for the bottom 3 to have a height E which is greater than about 15% of the diameter B of the annular zone forming a base.

Also, it may be desirable for the height F of the dome to be between about 10% and 50% of the height C of the vault, i.e. the total height D of the cavity formed by the dome 6 and the vault 4 (in other words cumulative heights F of the dome 6 and C of the vault 4) is between 1.10% and 1.50% of the height C of the vault 4.

$$0,10\mathrm{B}<\mathrm{C}<0,25\mathrm{B}$$

$$1,10\mathrm{C}<\mathrm{D}<1,50\mathrm{C}$$

$$0,15\mathrm{B}<\mathrm{E}$$

Finally, the geometry of the bottom 3 can advantageously respond to the following relationships: $$0,70\mathrm{AT}<\mathrm{B}<0,90\mathrm{AT}$$

$$0,10\mathrm{B}<\mathrm{VS}<0,25\mathrm{<figure-callout\; id="10"\; label="B"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">B</figure-callout>}$$

$$1,10\mathrm{VS}<\mathrm{D}<1,50\mathrm{VS}$$

$$0,15\mathrm{B}<\mathrm{E}$$

Thanks to the provisions that have just been described, a container 1 made of a thermoplastic material such as PET equipped with a bottom 3 which is arranged according to the invention and which, while consisting of a smaller amount of thermoplastic material, is adapted to withstand the hydrostatic pressure due to the increased liquid column with a nominal overpressure of about 1x10 ⁵ Pa, about 2 × 10 ⁵ Pa, without said bottom suffering significant deformation.

Of course, the arrangements just described are likely to give rise to many variants.

Thus, in the example described above and represented in Figures 2A and 2D the arch 4 is curved and the zones 11 in the form of claws constitute curvilinear plates. Alternatively, in the embodiment of the bottom 3 illustrated in FIGS. Figures 3A and 3B , the roof 4 is always concave concavity turned towards the outside of the container; however this vault is no longer convex but frustoconical surrounding the dome 6. Thus, as we see better at the figure 3A the bottoms 13 of the grooves 12 are substantially flat and inclined while the zones 11 in the form of claws constitute substantially flat plates and inclined. For the rest, the bottom 3 illustrated in Figures 3A and 3B remains identical to what has been described above.

Claims (8)

Container (1), in particular a bottle, made of thermoplastic material such as PET, having a body (2) extending between, superiorly, a neck and, below, a bottom (3) able to withstand, without significant deformation, the hydrostatic pressure due at the increased liquid column with an overpressure not exceeding about 2 x 10 ⁵ Pa, said bottom (3) comprising: A concave arch (4) with a concavity turned towards the outside of the container (1), A dome (6) projecting towards the inside of the container (1) and concavity facing outwards, opening at the center of said vault (4), An annular zone (5) surrounding the base of said vault and forming a substantially plane base by which said bottom (3) can rest stably on a plane support, and · Ribs in the form of grooves open towards the outside, of substantially radial extent passing through said annular zone (5) forming a seat and going up on the wall (8) connecting with the wall (9) of the body (2) of the container, characterized in that said bottom (3) comprises: - zones (11) in the form of claws, separated from each other, which extend the bottom of the body (2) radially in the direction of the central axis (X) of the bottom (3) and which are offset in external projection by relation to said vault (4), and - radial grooves (12) delimited between said zones (11) in the form of claws, grooves (12) whose bottom (13) is formed by radial sections (4a) of said arch (4) and which have a depth ( p) radially variable which is maximum approximately to the right of said annular zone (5) forming a seat. Container according to claim 1, characterized in that the radial ends (14) of said claw-shaped areas (11) are spaced from the edge (15) of said dome (6). Container according to any one of claims 1 or 2, characterized in that the arch (4) is curved. Container according to any one of claims 1 or 2, characterized in that the arch (4) is frustoconical. Container according to any one of claims 1 to 4, characterized in that the dome (6) is curved. Container according to one of Claims 1 to 5, characterized in that said annular zone (5) forming a seat has a diameter (B) which is between approximately 70% and 90% of the diameter (A) of the body (2), and - In that said vault (4) has a height (C) which is between about 10% and 25% of the diameter (B) of the annular zone (5) forming a seat. Container according to any one of claims 1 to 6, characterized in that the bottom (3) has a height (E) which is greater than about 15% of the diameter (B) of the annular zone (5) forming a seat. Container according to any one of claims 1 to 7, characterized in that the height (F) of the dome (6) is between about 10% and 50% of the height (C) of the arch (4).

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