PLASTIC CONTAINER WITH TENSION BAND GEOMETRY AT BASE REGION

Abstract

A one piece plastic container for beverages, has a base region, a main body extending in the longitudinal direction of the plastic container to the base region and a mouth region with a container mouth, with the mouth region adjoining the main body in the longitudinal direction at least indirectly, wherein the base region has at least three standing feet, wherein at least one groove having a groove base extending in the circumferential direction over a circumferential angle is arranged between two, in particular adjacent feet. The wall of the container is curved inwards at least in sections in the region of the groove base of a groove.

Claims

1. A plastic container, in particular for beverages, having a base region, a main body extending in the longitudinal direction (L) of the plastic container to said base region and a mouth region with a container mouth, with the mouth region adjoining said main body in the longitudinal direction (L) at least indirectly, wherein the base region has at least three standing feet, wherein at least one groove (30) having a groove base extending in the circumferential direction (U) over a circumferential angle is arranged between two, in particular adjacent standing feet, wherein the container is formed in one piece, wherein the wall of the container is curved inwards at least in sections in the region of the groove base of a groove.

2. The plastic container (1) according to claim 1, wherein at least one groove base has a circumferential angle which is between 2.5 and 20, preferably between 5 and 15.

3. The plastic container according to claim 1, wherein the curvature of a line formed along the base region, which extends from a standing foot or a standing region surrounding a standing foot over at least one groove base, changes in the groove base by less than 30%, preferably by less than 25%, preferably by less than 20% and particularly preferably by less than 15%.

4. The plastic container according to claim 1, wherein the wall of the container is curved inwards at least in sections in a laterally adjacent region of a geometric centre of the groove base.

5. The plastic container according to claim 1, wherein the wall of the container is curved inwards at least in sections along a geometric centre of the groove base.

6. The plastic container according to claim 1, wherein a width (BR) of the groove base increases outwards in a radial direction of the container.

7. The plastic container according to claim 1, wherein a region of the base section, which region is arranged between a standing foot and a groove base, merges in a tangent-continuous and/or curvature-continuous manner into the groove base.

8. The plastic container according to claim 1, wherein at least one line which runs in the radial direction, runs on the surface and runs at least in sections through a groove base, has an inflection region in which a surface region of the base section changes the orientation of its curvature and, in particular, is transferred from an outwardly curved region into an inwardly curved region.

9. The plastic container according to claim 1, wherein a groove basic cross-sectional contour with a cross-section along the longitudinal direction L of the container follows a spline of n-th degree at least in sections and preferably substantially completely.

10. The plastic container according to claim 1, wherein a section of a and preferably of each groove base, which can be described by a spline, merges continuously and/or with a constant curvature into a, and preferably straight, section (SA, SB) of the base region, which section adjoins the spline.

11. A blow-moulding device for producing plastic containers having an inner wall, against which a plastic container can be expanded during a blow-moulding operation, wherein the inner wall has a contour which is configured to produce a plastic container as claimed in claim 1.

12. A method for shaping a plastic container from a plastic preform using the blow moulding device as claimed in claim 11, comprising the steps: Preliminary blow moulding by acting upon the plastic preform with a first pressure, intermediate blow moulding of the plastic preform at a second pressure which is higher than the first pressure; and final blow moulding the plastic preform at a third pressure which is higher than the second pressure, wherein this third pressure is between 13 bar and 24 bar.

13. The plastic container according to claim 2, wherein the curvature of a line formed along the base region, which extends from a standing foot or a standing region surrounding a standing foot over at least one groove base, changes in the groove base by less than 30%, preferably by less than 25%, preferably by less than 20% and particularly preferably by less than 15%.

14. The plastic container according to claim 2, wherein the wall of the container is curved inwards at least in sections in a laterally adjacent region of a geometric centre of the groove base.

15. The plastic container according to claim 2, wherein the wall of the container is curved inwards at least in sections along a geometric centre of the groove base.

16. The plastic container according to claim 2, wherein a width (BR) of the groove base increases outwards in a radial direction of the container.

17. The plastic container according to claim 2, wherein a region of the base section, which region is arranged between a standing foot and a groove base, merges in a tangent-continuous and/or curvature-continuous manner into the groove base.

18. The plastic container according to claim 2, wherein at least one line which runs in the radial direction, runs on the surface and runs at least in sections through a groove base, has an inflection region in which a surface region of the base section changes the orientation of its curvature and, in particular, is transferred from an outwardly curved region into an inwardly curved region.

19. The plastic container according to claim 2, wherein a groove basic cross-sectional contour with a cross-section along the longitudinal direction L of the container follows a spline of n-th degree at least in sections and preferably substantially completely.

20. The plastic container according to claim 2, wherein a section of a and preferably of each groove base, which can be described by a spline, merges continuously and/or with a constant curvature into a, and preferably straight, section (SA, SB) of the base region, which section adjoins the spline.

Description

[0089] Further advantages and embodiments will become apparent from the accompanying drawings Therein:

[0090] FIG. 1 is a schematic illustration of a plastic container;

[0091] FIGS. 2, 3 and 6 are different illustrations of a base portion of a plastic container according to one embodiment of the prior art;

[0092] FIGS. 4, 5, 7 and 8 each show a different representation of a section of the base region of the plastic container according to the embodiment of the prior art (according to FIGS. 2, 3 and;

[0093] FIG. 9 shows a measurement result of the material distribution on a container base of the plastic container according to the embodiment of the prior art;

[0094] FIGS. 10 and 11 each show an illustration from different perspective of a base region of a plastic container according to the invention, according to one embodiment;

[0095] FIGS. 12, 13, 21, 22 and 23

[0096] In each case a comparison of the tension band or groove base of the plastic container according to the embodiment of the prior art with a tension band or groove base according to the embodiment of a plastic container according to the invention;

[0097] FIGS. 16, 17, 27 and 28

[0098] In each case a base region according to the embodiment of a plastic container according to the invention with a tension band or groove base of the plastic container according to the embodiment of the prior art;

[0099] FIG. 14 shows a course of curvature of a base line, which is formed on the base region according to the embodiment of a plastic container according to the invention;

[0100] FIGS. 15, 25 and 26 each show a further comparison of the tension band or groove base of the plastic container according to the embodiment of the prior art and of the tension band or groove base according to the embodiment of a plastic container according to the invention;

[0101] FIG. 24 shows the base section of FIG. 14 with surface shading;

[0102] FIG. 18

[0103] Is a section of a base portion of a preferred embodiment of the present invention;

[0104] FIGS. 19 and 29 are an enlarged view of a portion of a base portion of a preferred embodiment of the present invention;

[0105] FIG. 20 shows a comparison of a contour line KL2 of a groove region according to a preferred embodiment according to the invention of a groove region of a container with a contour line KL1 of a groove base of a container from the prior art.

[0106] FIG. 30 shows a preferred embodiment of the tension band or groove base of a plastic container according to the invention; and

[0107] FIG. 31 shows a further preferred embodiment of the tension band or groove base of a plastic container according to the invention.

[0108] FIG. 1 shows a schematic representation of a plastic container 1. This plastic container has a mouth region 6 with container mouth 8 and a main body 4 adjoining the mouth region 6. The main body 4 serves to accommodate the essential filling volume. The main body can also be designed differently in its shape than shown in FIG. 1 and can, for example, have waves or patterns. The mouth region 6 can have an external thread of the plastic container 1 and a support ring located on the container mouth 8. The container according to the invention also preferably has an external thread and a supporting ring.

[0109] The reference symbol L indicates a longitudinal direction of the plastic container 1. As illustrated, here, the longitudinal direction L is a direction along the central axis N of the container. In addition, FIG. 1 shows a circumferential direction U, which is a direction of rotation about the central axis or the longitudinal direction L as the axis of rotation.

[0110] The main body 4 is adjoined by a base region 2 of the plastic container, wherein the main body 4 can transition into the base region 2 via a curved section or else via a non-curved section.

[0111] Reference numeral 22 designates a standing foot (not shown here) of the container. The base region 2 may have a plurality of standing feet 22 with which it can stand upright on a straight surface. The reference symbol R refers to a radial direction with respect to the central axis M or the longitudinal direction L of the plastic container. In this case, the radial direction R is perpendicular to the central axis N and the longitudinal direction L and runs either towards or away from the latter. The reference numeral 50 designates a side wall of the main body 4. This side wall 50 extends over the entire circumference in the circumferential direction U of the container.

[0112] The two FIGS. 2 and 3 each show an illustration of the base region 2 in a different perspective view. This is a base section known from the prior art. There are five standing feet 22 on which the container can stand. The reference numeral 24 designates in each case a region of the base region 2 which extends radially outwards from the centre axis M from the centre axis M and in each case encloses a (exactly one) standing foot 22. In this case, the standing area 24 preferably does not extend beyond the standing foot 22 when viewed in the circumferential direction U. The standing region 24 is preferably an region of the base region 2, which is defined by a predetermined angular segment in relation to a rotation in the circumferential direction U about the center axis M as the axis of rotation.

[0113] Viewed in the radial direction, the standing regions 24 run together in the direction of the central axis M and meet in the injection point 18 of the container. In an orientation of the container standing on a plane, the injection point 18 does not touch this plane. Viewed in the longitudinal direction L, the injection point 18 is thus located above the standing feet 22, that is to say closer to the mouth region than in each case the standing feet 22.

[0114] A groove 30 is formed between in each case two adjacent feet. In this case, a groove can be understood as meaning a geometric structure which extends inwards with respect to the circumferential wall, that is to say approximately the wall of the base region.

[0115] The reference numeral 32 designates the groove base of a groove. The groove base 32 is a region around the geometric centre 34 of a groove. This is a region which essentially follows a hemispherical course in the embodiment of a container according to the prior art shown in FIG. 2 and FIG. 3. Individual formed lines formed in the radial direction at the injection point 18 toward the outside or toward the side wall or toward the main body, on the base region 2 of the groove base 32, are similar to or follow a circular course. Such a selection of the geometric curve of the groove base 32 has proven to be advantageous in particular with regard to a force transmission of a force acting on the injection point against the longitudinal direction on a side wall of the main body 4.

[0116] The two FIGS. 4 and 8 show a line representation (FIG. 4) or illustrate (FIG. 8) a section of the base region 2 which corresponds to an angle segment at the geometric center 34 of a first groove 32 to the geometric center 34 of an adjacent second groove 32. Only one half of each groove 32 is shown. In addition to the geometric center 32, a boundary line is shown as a further line 36, which delimits the groove base 32 with respect to a region of the base region 2 of the groove 30 arranged laterally thereon. The groove base 32 of a base region 2 of the prior art is designed, for example, in such a way that approximately the boundary line 36 is rotated about the central axis M in the circumferential direction (or counter to the circumferential direction) by an angle 1+2. The two angles 1 and 2 are the same.

[0117] In a similar manner, a standing region 24 of a base region 2 of a container according to the prior art and in particular also according to a base region 2 of a plastic container 1 according to the invention is advantageously constructed. For this purpose, for example, a predetermined line profile 26 is rotated about the centre axis M by an angle in or against the circumferential direction U.

[0118] In addition, the two FIGS. 4 and 8 show base lines BL1, BL2 and BL3 which run on the outer surface of the container base and are each formed in such a way that a projection of these base lines in each case along the longitudinal direction onto a plane perpendicular to the central axis M follows a circular line. The curve course KL1 to KL3 corresponding in each case to a projection of the ground lines BL1 to BL3 in the plane E therefore follows a circular course, as can be seen in FIG. 4. It can be seen from FIGS. 4 and 8 that the base lines BL1, BL2 and BL3 each have no curvature in the region of the standing region 24 (when viewed in the radial direction). In other words, the base lines BL1, BL2 and BL3 extend within the standing region 24, here as a circular line in a plane which is (for example) perpendicular to the longitudinal axis or the central axis.

[0119] Similarly, the base lines BL1, BL2 and BL3 in the area of the groove base 32 are each uncurved (or even have a straight course) or only slightly curved. The base lines BL1, BL2 and BL3 here likewise run in the respective standing regions 24 as a circular line in a plane which is perpendicular to the central axis or a longitudinal direction L.

[0120] The two FIGS. 5 and 7 again illustrate a construction of the standing regions 24 and of the groove base 32 of a container according to the prior art. In this case, the two FIGS. 5 and 7 each show an illustration of two cutouts of the container base. Only one standing region 24 and one half of a groove base 32 are shown here. The groove base 32 is shown only up to its geometric centre 34. Also shown for illustration of the construction is a hypothetical or imaginary plane E, which is perpendicular to the central axis M. The hypothetical or imaginary plane E, which is perpendicular to the center axis M, is illustrated by an ellipse in FIGS. 4, 5, 7 and 8. The planes E shown therein are that plane which is perpendicular to the central axis M and delimits the base region 2 from the main body 4.

[0121] Illustrated in both FIGS. 5 and 7 are projections of the boundary lines 26 on the plane E, which leads to the two straight lines P26, each of which runs in the radial direction toward the centre axis M. Likewise, the projections of the boundary line 36 of the groove base 32 as well as the geometric centre 34 of the groove base 32 in their projection onto the plane E also result in a rectilinear straight line running in the radial direction onto the centre axis M. These two projected lines are identified by reference numerals P36 and P34. It can be seen that the two lines P36 and P34 enclose the angle 1. A complete groove base corresponds to an angular segment which extends over a double angle . The two projected lines P26 enclose an angle . This shows that the standing area 24 corresponds to a container base cutout which corresponds to an angle segment which extends over the angle . In this case, the angle segments are obtained by rotations by a specific angle with respect to the central axis M or the longitudinal direction L in the circumferential direction.

[0122] In the case of the prior art container base 2 illustrated in FIGS. 2-8, the groove base 32 (in each case) functions as a tension band which intercepts approximately loads, in particular also in the direction of this tension band.

[0123] As shown in FIG. 5, in the case of the container base 2 of the prior art, the tension band is a segment (of the container base) which is rotated by an angle X.

[0124] FIG. 6 illustrates a further illustration of a prior art container base 2. The five standing feet as well as the respective associated standing areas 24, which are delimited by the lines 26, are again recognizable. The boundary lines 26 extend from the injection point 18 in the radial direction toward the outside toward a side wall of the base body in a centre point of the container base. In turn, a base line BL3 is shown starting from a boundary line 26 of a standing area 24 over a groove base 32 as far as a boundary line 26 of an adjacent standing area 24.

[0125] A course of curvature of the surface wall along the base line BL3 is drawn around this base line BL3 with KV3. It can be seen that the base line BL3 has a changing curvature starting from the boundary line 26 and the orientation or orientation of the curvature in the area adjoining the standing area 24 reverses to the inflection point W and then the curvature initially increases, reaches a maximum and steadily decreases again up to the boundary line 36 of the groove base 32. The course of curvature of the base line BL3 is represented here by the gray bar in the region of the groove base 32. In any case, however, the base line BL3 in the groove base 32 does not have a varying curvature.

[0126] The reference numeral 40 designates a foot flank surface which (viewed in the circumferential direction) is arranged between a standing region 24 and/or a standing foot 22 on the one hand and the groove base 32 or the tension band 32. As shown in FIG. 6, a base line (such as BL3) of the prior art base has a constant course of curvature in the area of the tension band 32.

[0127] In FIG. 8, reference numeral 25 designates the foot geometry (of the standing foot or standing area). The two reference symbols 32 in turn characterize the two tension bands of the prior art base shown in FIG. 8.

[0128] FIG. 9 shows a measurement result of the material distribution on a container base of the plastic container according to the embodiment of the prior art. The encircled region characterizes a region of the tension band at the base of the plastic container after the PET material has been blown with blowing pressure to a (blowing) form by means of a blowing process. In the embodiment of the predetermined blow mould or predetermined shape of the plastic container of the prior art which is to be achieved or produced, too much material remains suspended on the draw band of the base and cools very quickly so that the material can no longer be properly stretched.

[0129] In this case, unattractive material accumulations occur on the tension band, which are characterized in FIG. 9 by the circle drawn in. These (unattractive) material accumulations reduce on the one hand the optics of the (ready-blown) plastic container, but on the other hand also reduce the soil performance in the form of wall thickness, bursting test, thermal test and stress-crack result, for example at 0.2| to 5| (filling) volumes.

[0130] FIGS. 10 and 11 each show (different) views of a base region 2 of a plastic container 1 according to the invention, according to one embodiment. In comparison to the base area 2 of the prior art base (shown approximately in FIGS. 2-8), the base area 2 has a new, improved tension band geometry.

[0131] The two FIGS. 12 and 13, as well as FIG. 21 (corresponding to the dashed line representation in FIG. 12) and 22 (corresponding to the dashed line representation in FIG. 13) and also FIG. 23, show different perspective views of a base region 2 according to the invention with a tension band 62 or groove base 62. modified in comparison with the groove base 32 or tension band 32 of the prior art base selected in FIGS. 2-8. The reference numeral 62 characterizes the tension band geometry of the new improved tension band. Reference numeral 32 denotes the tension band geometry of the prior art.

[0132] In the new tension band 62, a larger segment (from 5 to 15) than in the prior art was used for construction in order to add a harmonious transition from the tension band into the foot flanks (surface 40), so that the material can slide better into the foot flanks and can be drawn from the center in the radial direction.

[0133] The tension band geometry 62 here has an at least tangential- and/or curvature-continuous transition into the foot flanks (surface 40).

[0134] FIGS. 12 and 13 also show base lines BL1-BL3 formed on the base region, which follow a circular course in the projection in the longitudinal direction L onto a plane E, which is perpendicular to the longitudinal direction L and the centre axis M. Each of these base lines has a sinusoidal course. Depending on the position of the individual base lines with respect to the radial direction R, these have different amplitudes, the largest amplitudes having those base lines BL2 in the vicinity of a standing foot 22.

[0135] Similarly, FIGS. 16 and 17, as well as FIG. 27 (corresponding to the dashed line representation in FIGS. 16 and 28 (corresponding to the dashed line representation in FIG. 17, show comparison of a groove base 62 in accordance with a preferred embodiment of the present invention to a groove base 32 constructed in accordance with a prior art base region (such as that of DE 10 201 3 110 139 A1) from a different perspective view.

[0136] In addition to the respective boundary lines 66 of the groove base 62, the position of the geometric centre 64 of this groove base 62 can also be seen, while the region of the groove base 62 surrounding the geometric centre 64 has not been shown or cut out. As a result, it is possible, in the same illustration, to also represent the geometric position of the prior art groove base 32, which is located on the side of the base region facing the container interior according to the preferred embodiments according to the invention shown in FIGS. 16, 17, 27 and 28.

[0137] In particular, the geometric center 64 of the prior art groove base is preferably spaced apart substantially along its entire length.

[0138] FIG. 14 shows a cutout of a base region according to the invention in the region of a groove 60. The groove base 62 and an adjacently arranged standing foot 22 and standing region 24 are seen. The container base, starting from the standing foot 22 and a standing region 24, merges via a foot flank surface 40, in particular on both sides, into a groove base 62.

[0139] Again, it can be seen that the foot flank surfaces 40 have a transition to the tension band 62 which is at least tangential- or curvature-continuous. Furthermore, the (new) tension band 62 here has a curved course (of a base line, for example of the drawn-in base line BL3) in the region of the tension band.

[0140] The new tension band geometry 62 makes it possible to better control the material distribution in the tension band 62. Since the PET material can slide better with the curved course, the accumulations of material from the old tension band 32 (of the prior art base) are eliminated. As a result, the positive effects are obtained that the material can be distributed even better, and can thus be drawn into the flanks of the foot and higher in the tension band.

[0141] This has positive effects on the wall thickness in the soil, the thermal test, the bursting test and the stress crack. This is particularly noticeable at the 2.0| to 3.5| volumes, but will also have the same effect at the smaller volumes. The final blowing pressure can therefore preferably be reduced.

[0142] FIG. 14 furthermore shows a base line BL3, which runs from a boundary or edge of the standing area 24 over the foot flank surface 40 towards the groove base 62, extends over the latter and from there extends over a further foot flank surface 40 to the lateral edge or lateral boundary of a standing area 24 of the adjacently arranged standing foot. As can be seen, the base line BL3 does not run over the standing surface of the container, but in a region of the container base, which lies between the standing region of the container base and the main body. The base line BL3 therefore runs in a middle (viewed in the longitudinal direction) region of the container bae. The course of a base line in this area is comparable with the course of a base line which extends over the standing area of the container floor or standing foot, however, since the central area of the container base already represents a transition area to the main body of the container, the amplitudes or deflections of the base line BL3 in the longitudinal direction are no longer as strongly pronounced as in the case of a base line running in the standing area of the container.

[0143] Also shown in FIG. 14 by the line KV3 is a curve of curvature of the base line BL3. The line KV3 shows a measure for the curvature at a respective point of the base line BL3.

[0144] It can already be seen from the course of the base line BL3 itself that, when the course of the base line from the left-hand side of the figure follows in the direction of the right-hand side of the figure, first a first region of the groove and a first region of the foot-flank surface 40, which in particular laterally adjoin a standing foot (not shown) and a standing region (not shown), is curved outwards. In relation to the plane of the figure or the plane of the paper, this region has a curvature (or curvature) outwards, that is to say out of the plane of the paper or the plane of the figure. As the curvature curve KV 3 shows, the curvature initially increases strictly monotonically and in a continuous manner until a maximum curvature value is reached and decreases continuously and in a strictly monotonous manner until a value 0 is reached. At this point of the base line, it has an inflection point at which the orientation or sign of the curvature reverses. The reference symbol W1 indicates the position of the inflection point on a base line, BL3 between a standing region and the groove base. After reaching this inflection point W1, the curvature value continues to decrease continuously and in particular in a strictly monotonous manner. As can be seen from FIG. 14, the magnitude of the curvature value increases steadily after reaching the inflection point W1. It is possible that the magnitude of the curvature value decreases again shortly before reaching the groove base.

[0145] After reaching the inflection point W1, therefore, as can also be seen from the subsequent course of the base line BL3 of FIG. 14, the region of the foot flank surface 40 or the groove is curved in the other direction, ie toward the inside. Toward the inside, in this case, in the direction of the interior of the container and in the choice and position of the base line BL3 shown in FIG. 14, a curvature is directed into the plane of the figure or into the plane of the drawing.

[0146] The reference numeral 62 in turn characterizes the region of the groove base, which in particular has the functions of a tension band. It can be seen that the groove base from the injection point 18 or from the geometric center of the container base or base region 2 of a container 1 increases in the radial direction toward the outside or in the radial direction toward a side wall of the main body. The groove base 62 corresponds to a predetermined angular segment of the base region. In particular, the two boundary lines, which are identified by the reference numeral 66, enclose the same predetermined circumferential angle relative to the central axis and a rotation in the circumferential direction about the central axis over their entire extent in the radial direction.

[0147] Referring now to FIG. 14, there are shown two aspects which distinguish the container base according to the present application from a container base according to the prior art. On the one hand, the circumferential angle of the groove base is substantially greater than the circumferential angle from the prior art. The groove base thus preferably extends over a comparatively larger opening angle or circumferential angle. On the other hand, the groove base is curved inwards along the base line BL3. This inward curvature is symbolized by the course of the curvature line KV3 below the course of the base line BL3. From a region out of the container interior, such as, for example, from a mouth region of the container or from the region of the central axis M of the container, which is arranged closest to the region of the base line 3, concavely curved.

[0148] In the embodiment of a base region illustrated in FIG. 14, the base region has a varying curvature along the base line BL3 in the region of the groove base, that is to say between the two points BN on the base line BL3. In particular, the curvature value in the region of the groove base 62 along the base line BL3 is just not constant. It is conceivable, for example, that the magnitude of the curvature value initially decreases continuously and in particular (strictly) monotonically, preferably at the geometric centre of the groove base, reaches a minimum amount of the curvature value and increases monotonically from there continuously and (strictly) monotonically. Preferably, the magnitude of the curvature value at the two edges of the groove base along a base line assumes a maximum value.

[0149] As can be seen from FIG. 14, the course of curvature KV3 along the base line BL3 in the region which adjoins the groove base to the right side of the figure is corresponding to that curve KV3 which adjoins the groove base 62 to the left side. Thus, the base line BL3 extends first through a region of the container base, which has a curvature inward. In a region of the groove and in a region of the foot flank surface 40, the curvature curve KV3 reaches a point W2 at which the curvature is 0. W2 thereby characterizes a further point of inflection of the curvature. Following this inflection point W2, the curvature or curvature again reverses, so that between this inflection point W2 and the standing region 24 of the standing foot arranged adjacently along the base line BL3, outwardly curved or outwardly curved wall regions are present.

[0150] Considering the course of curvature KV3 along the base line BL3 at the two points BN at which the groove base merges into the remaining region of the groove or the foot flank surfaces 40, it can be seen from FIG. 14 that the curvature at these points has a jump. The course of curvature KV3 of a base line BL3 cannot be continuous, in particular at a region in which the groove base 62 merges in a laterally adjacent region (for example, the remaining groove and/or a foot flank surface). However, unlike in the embodiment illustrated here, it is also conceivable that the course of curvature is also constant in curvature at the points BN in which the groove base merges along a base line BL3 in a region 40 (such as a foot flank surface and/or a remaining region of the groove) arranged laterally on the groove base 62.

[0151] Preferably, the groove base 62 has a region in which the wall of the container base is curved inwards at each point, this region being arranged between an injection point 18 and/or a central region surrounding this injection point 18 and/or a inflection region surrounding the central region and/or the injection point on the one hand and a inflection region WN arranged adjacent to the basic body of the container. Preferably, this region almost completely occupies the region of the groove base 62 between the injection point or a central region surrounded by the latter and the adjacent main body. Preferably, there is a inflection region WN in the vicinity of the main body, in which the wall of the base region is no longer curved inwards, but is preferably curved outwards.

[0152] Following an imaginary line along the container wall in the radial direction to the outside, corresponding to the course indicated by the arrow PR in FIG. 14, and considering in each point of this imaginary line a base line, such as symbolically indicated by the base line BL3, the curvature of each individual of these base lines runs over the entire course of the imaginary line in a similar manner to that of the base line BL3, and in particular the respective curvature has the same orientation over almost the entire course of the imaginary line, such as that of the base line BL3. The orientation of the curvature of such a base line preferably changes only when the inflection region WN is reached. Preferably, the radial extent of this inflection region, in which the orientation of the curvature of a base line changes, in particular in the region of the geometric centre of the groove base, changes in such a way that the wall of the container base is no longer curved inwards in this region, less than 20%, preferably less than 10%, preferably less than 5% and particularly preferably less than 2.5% of the container diameter on the circumferential line UL and in particular the point of intersection with the geometric centre of the groove base. The circumferential line UL describes in particular a boundary and/or a transition between the base region of a container and the main body of a container.

[0153] For ease of illustration of the three-dimensional shape, FIG. 24 shows the base portion of FIG. 14 with corresponding surface shades.

[0154] FIG. 15 and the two dashed line representations of FIGS. 25 and 26 show a further comparison of a portion of the prior art container base with a portion of a container base in accordance with a preferred embodiment of the present invention. These figures illustrate in a special way the different construction of the tension band or groove base of the container base.

[0155] The container base is illustrated from a viewing direction against to an almost radial direction approximately from the outside in the direction of the central axis. The regions between two adjacent feet are shown, the standing regions of the containers themselves being no longer shown. The groove 60 between the two feet is formed, among other things, and/or bounded by the two foot flank surfaces 40.

[0156] Reference numeral 62 designates the groove base according to a preferred embodiment of the present invention. This groove base 62 is not shown in its entirety, but is cut out around the region of a geometric center of the groove base along the two lines 36. The dashed line 64 shows the course of the geometric center of the groove base according to the preferred embodiment of the present invention. The two lines indicated by the reference numeral 66 show the transition or boundary of the groove base to the laterally adjacent region, for example the foot flank surfaces 40.

[0157] As a result of the cutout from the groove base 62, it is possible to present a groove base 32 which is constructed according to the prior art and which is located further close to the central axis of the container in the radial direction in comparison with the groove base 62. The reference numeral 34 designates the geometric centre of the state-of-the-art groove region 32. The geometric centre 32 is enclosed over its entire course, in particular in the same way as the prior art groove base 32 from a groove base 62 according to a preferred embodiment of the present invention. In other words, the state-of-the-art groove base and in particular its geometric centre 34 is preferably arranged in the interior of the container, which has a bottom base according to an embodiment of the present invention.

[0158] FIG. 18 shows a portion of a base region of a preferred embodiment of the present invention. An angle segment of the base region between a standing foot 22 and the geometric center of a groove base 62 can be seen. It can be seen that the linear guide over the standing foot 22 as well as the geometric centre of the groove base 62 in each case converge inwards in the radial direction and meet in the geometric centre 19 of the container. The foot 22 merges over the foot flank surface, which in turn is identified by the reference numeral 40, into the groove base 62. The boundary line of the base region, which is located furthest outward in the radial direction, relative to the geometric center 19, is again identified by the reference symbol UL. The reference numeral KV designates the course of curvature of a line along the geometric center of the groove base 62. It can be seen here that, in a region which is arranged close to and/or adjacent to the circumferential line UL and thus close to the main body of the container, the curvature curve KV has an inflection point.

[0159] This is particularly clearly recognizable in FIGS. 19 and 29 (FIG. 29 corresponds to the broken line representation in FIG. 19, through the crosses K1 and K2 shown therein). The two representations in FIGS. 19 and 29 correspond to enlarged representations of a base region at the intersection of the geometric centre of a groove base and the circumferential line UL or the edge region of the base region, which is arranged adjacent to the main body in the longitudinal direction.

[0160] Finally, FIG. 20 shows a comparison of a contour line KL2 of a groove region according to a preferred embodiment according to the invention of a groove region of a container with a contour line KL1 of a groove base of a container from the prior art. The reference symbol KR characterizes the course of curvature of the contour line KL1.

[0161] The two contour lines KL1 and KL2 can be formed, for example, from the formation of a cross section of the container base with a plane which extends in the longitudinal direction and in a radial direction and through the groove base approximately through its geometric centre. As can be seen from FIG. 20, in the improved tension band or groove base, the surface of this tension band approaches in such a cross-sectional representation of the contour line or radius of the tension band, in particular in its geometric centre. However, as a result of the increased opening angle in comparison with the prior art, which is used to construct the tension band or groove base according to the present application, the spline for the creation of the new tension band surface or of the new groove base is defined in the foot flank, as a result of which the deviation occurs in a central region (see FIG. 20).

[0162] FIG. 30 shows a preferred embodiment of the tension band or groove base of a plastic container according to the invention 1. According to this preferred embodiment, the tension band cross-sectional contour with the two radii R RFU and R 42,441 is connected from the centre to the circumference of the bottle.

[0163] This geometry cannot absorb sufficient force at an internal pressure of up to 5.5 bar. For this reason, the base centre around the injection point can no longer hold the desired base clearance in the finished blown bottle, which leads to the fact that the optics and the ground performance, in the form of wall thickness, bursting test, thermal test and stress crack result, can no longer be kept at such high internal pressures as the applicant has established in complicated laboratory tests.

[0164] The reference numeral 33 in FIG. 30 characterizes a groove base cross-sectional contour or a tension band cross-sectional contour, which can be obtained, for example, with a cross section along the longitudinal axis L of the container through a base region (in the region of a groove base or tension band) of the container. As illustrated by the two radii RS (or R 42,441) and R RFU=6,500 in FIG. 30, the groove base cross-sectional contour or a tension band cross-sectional contour has two circular-line-shaped sections (with different radii). Point A and point B designate points of the groove base cross-sectional contour or the tension band cross-sectional contour, in which the latter merges into a straight section and/or from which a straight course follows.

[0165] FIG. 31 shows a further preferred embodiment of the tension band or groove base of a plastic container 1 according to the invention, in which the two radii from FIG. 30 are replaced by a spline for further improvement of the tension band cross-sectional contour. The curvature of the spline can preferably be described by a polynomial of the n-th degree. The degree n is preferably between degree 2 and degree 7. The transition from the centre of the base, designated by point A in FIG. 31, (to the tension band) is particularly preferably continuous in curvature, but preferably at least tangential continuous. The transition from the spline (in particular from the tension band, preferably formed by a spline) into the circumference of the bottle, in FIG. 31, characterized by point B, is preferably continuous in curvature, but preferably at least tangential continuous. This offers the advantage of improving the base clearance on the blown bottle.

[0166] The transition control can be controlled by the tangent values of the spline at points A and/or B. The values for the magnitude of the tangent vector (which in particular represents the percentage of the tangential in the start and end values) can move between 0.1 and 2.5. The values may be the same in points A and B, but they may also be different.

[0167] A further variant of the spline can be described by a conical transition control. Here, the transition control is controlled by a value Rho. This value may be between 0.01 and 0.99. In particular, a small Rho value produces a flat cone while a large Rho value produces a sharp cone.

[0168] In FIG. 31, in addition to the possible groove base cross-sectional contour 33 or tension band cross-sectional contour 33 known from FIG. 30, a further preferred embodiment of a base contour of a groove base or a tension band (or groove base cross-sectional contour or tension band cross-sectional contour 35) is shown, which is characterized by the reference number 35. It preferably has a region which can be described by a spline of the n-th degree.

[0169] This spline preferably adjoins a base body connection region SB, which preferably has a straight section and/or is configured in a straight line, and which adjoins the main body of the container. The spline preferably adjoins a centre point transition section SA, which adjoins a geometric centre of the container base or a central region of the container base or an injection point of the container.

[0170] The main body connection section preferably has a circular and/or curved section, which adjoins the spline, in particular.

[0171] Preferably, the mid-point transition section SA has a rectilinear section S1 and/or a further substantially rectilinear section S2, which likewise runs rectilinearly or has only a slight curvature (in particular in comparison with the spline in a central region of the spline).

[0172] Preferably, the spline of the base contour or groove base cross-sectional contour 35 can be completely included into a circular line. In other words, the spline lies completely within a circle, the circular line of which runs through an initial point and an end point of the spline.

[0173] Preferably, the spline occupies most of the arc length of the base contour of the groove base or most of the arc length of the groove base cross-sectional contour 35.

[0174] The applicant reserves the right to claim all the features disclosed in the application documents as essential to the invention in so far as they are individually or in combination novel over the prior art. Furthermore it is pointed out that in the individual drawings features were also described which may be advantageous per se. The person skilled in the art recognises immediately that a specific feature described in a drawing may also be advantageous without the incorporation of further features from this drawing. Furthermore the person skilled in the art recognises that advantages may also result from a combination of several features shown in individual drawings or in different drawings. [0175] 1 Plastic container [0176] 2 base area [0177] 4 main body [0178] 6 Mouth region [0179] 8 container mouth [0180] 18 Injection point [0181] 19 geometric center of the base wall (or base region) [0182] 22 standing foot [0183] 24 standing region/standing portion [0184] 25 Foot geometry [0185] 26 boundary line of the standing region 24 [0186] 28 geometric center of the standing region 24 [0187] 30 groove [0188] 32 groove base [0189] 33 groove base cross-sectional contour/tension band cross-sectional contour, base contour [0190] 34 geometric center [0191] 35 groove base cross-sectional contour/tension band cross-sectional contour, base contour [0192] 36 boundary line of the groove base 32 [0193] 40 Foot flank surface [0194] 50 side wall [0195] 60 groove [0196] 62 groove base [0197] 64 geometric center [0198] 66 boundary line of the groove base 62 [0199] a, b points of transition [0200] BL1, BL2, BL3 ground lines [0201] BN Boundary groove base [0202] KL1, KL2, KL3 are circular lines in plane E [0203] KV3 curve of curvature of the base line BL3 [0204] KV, KR Curvature course [0205] K1, K2 Cross [0206] KL1, KL2 contour line [0207] L longitudinal direction [0208] LW line [0209] M center axis [0210] p34, p36, p26 boundary lines 34, 36, and 26 projected on plane E [0211] PR arrow [0212] R radial direction [0213] S1, S2, SA, SB portions of the groove base cross-sectional contour [0214] U circumferential direction [0215] UL perimeter line [0216] W, WN inflection point [0217] W1, W2 Inflection point [0218] WB inflection region