Patent ID: 12214935

FIG.1shows a cap1for closing a container, particularly a bottle intended to contain a liquid substance such as a drink. The cap1is made of polymeric material. Any polymeric material suitable for moulding may be used to obtain the cap1.

The cap1is shown inFIG.1in a closed position in which the cap1is when it leaves a cap production line, ready to be applied on the container. In this condition, the cap1comprises a side wall2which extends about an axis Z, and a transversal wall3arranged at an end of the side wall2, so as to close that end. The transversal wall3extends transversally, in particular perpendicularly, to the axis Z. The transversal wall3may be flat, even though other shapes are theoretically possible. In the example illustrated, the transversal wall3has a substantially circular shape in plan view.

The cap1has a separation line4, positioned on the side wall2and extending about the axis Z. The separation line4extends on a plane arranged transversally, in particular perpendicularly, to the axis Z. The separation line4defines on the cap1a retaining ring5and a closure element6. The latter are positioned on opposite sides of the separation line4. As described in more detail below, when the cap1is brought to an open position, the closure element6separates from the retaining ring5along the separation line4.

Along the separation line4a plurality of breakable bridges7may be provided, which connect the retaining ring5to the closure element6. The breakable bridges7are intended to be broken the first time the cap1is moved to the open position, to signal that the container is no longer intact. The separation line4may be parallel to a free edge16of the cap1. More specifically, the free edge16delimits the retaining ring5on the opposite side to the transversal wall3.

The separation line4does not extend for an entire angle of 360° about the axis Z. The separation line4is interrupted in the circumferential direction, so as to define on the side wall2a joining portion8, at which the closure element6remains joined to the retaining ring5.

In other words, the separation line4has a first end9and a second end10. The joining portion8is interposed between the first end9and the second end10. At the joining portion8, the retaining ring5is joined to the closure element6.

As shown inFIG.1, the joining portion8has an angular dimension W about the axis Z.

No arrow shaped hinges or reduced thickness zones are provided in the joining portion8.

In the example illustrated, the closure element6has a cup-shaped body and comprises a skirt11which extends about the axis Z. The skirt11is connected to the transversal wall3, arranged at the end of the skirt11opposite the separation line4. In particular, the skirt11is connected to the transversal wall3by a connecting zone12, which may be shaped, in cross section, like a bevelled edge or a circular connection zone.

The skirt11has, on an inner surface thereof, a member for removably fixing, not shown, by which the closure element6can removably engage with the neck18of the container. The member for removably fixing may comprise, for example, an inner thread intended to engage with an outer thread17, shown inFIG.3, formed on the neck18.

The skirt11can be provided, on an outer surface thereof, with a plurality of knurling lines13, extending parallel to the axis Z and suitable for facilitating gripping of the cap1by the user or by the capping machine which applies the cap1on the container to be closed.

The knurling lines13may continue also in the connecting zone12and/or in the retaining ring5.

In the example shown, the skirt11comprises a cylindrical portion14on which the knurling lines13are made. The skirt11further comprises a wide portion15having a diameter larger than the cylindrical portion14. The wide portion15may be delimited by a smooth outside surface, that is to say, it can be free of knurling lines. This condition is not, however, necessary and the knurling lines could also extend on the wide portion15. Between the cylindrical portion14and the wide portion15a step19may be provided.

The retaining ring5extends between the free edge16and the separation line4. The retaining ring5may be delimited by a cylindrical or truncated cone shaped outer surface. In the closed position of the cap1shown inFIG.1, the retaining ring5is coaxial with the closure element6.

The retaining ring5is provided internally with an engagement element20, shown inFIG.2, suitable for engaging with a circular enlargement23, shown inFIG.3, which projects from an outer surface of the neck18. The engagement element20is configured to abut against the circular enlargement23in order to prevent axial movements of the retaining ring5, away from the neck18, when the closure element6is removed from the neck18.

The engagement element20may be shaped like an annular element which is bent around the free edge16towards the inside of the retaining ring5. In an alternative embodiment not illustrated, there may be a plurality of engagement elements, shaped like tabs which project from the free edge16and are bent towards the inside of the retaining ring5. Alternatively, the engagement element20may be shaped like an enlargement, continuous or interrupted, which from an inner surface of the retaining ring5projects towards the axis Z to engage with the circular enlargement23.

As shown inFIG.1, the cap1has an incision line21which extends on the side wall2transversally, in particular perpendicularly, to the axis Z. In more detail, the incision line21is interposed between the separation line4and the free edge16.

If the cap1is positioned in the same orientation which it will have after having been applied to the container, that is to say, with the transversal wall3facing upwards, the incision line21is arranged below the separation line4. The incision line21is therefore located on the side of the retaining ring5, relative to the separation line4.

The joining portion8is located on the opposite side of the incision line21relative to the retaining ring5. The incision line21therefore delimits the joining portion8towards the retaining ring5.

The incision line21has an angular extension A1, measured about the axis Z, greater than the angular distance (also measured about the axis Z) between the first end9and the second end10of the separation line4, that is to say, the angular dimension W of the joining portion8. For example, the angular extension A1of the incision line21may be between 60° and 200°, preferably between 75° and 180°. The angular dimension W of the joining portion8about the axis Z, that is to say, the angular distance between the first end9and the second end10of the separation line4, may be between 5° and 40°, preferably between 10° and 30°.

In the example illustrated, the joining portion8is centred relative to the separation line21. In other words, the midpoint of the separation line21and the centre line of the joining portion8are aligned with each other in a direction parallel to the axis Z, that is to say, they lie in a common plane which contains the axis Z. This condition is not however necessary, since even a not perfectly centred positioning of the incision line21relative to the joining portion8is permitted.

In the example illustrated, the incision line21has a flat arched shape. However, other shapes are possible.

The incision line21and the separation line4may be parallel to each other, even though this condition is not necessary. For example, the incision line21and the separation line4could be slightly inclined relative to each other. Alternatively, the incision line21could comprise a plurality of stretches having different inclinations, not necessarily parallel to each other.

As shown inFIG.1, the incision line21has an end27and a further end28. The end27extends outside the joining portion8, beyond the first end9of the separation line4. The further end28also extends outside the joining portion8, but goes beyond the second end10of the separation line4.

The incision line21comprises a central part24interposed between a peripheral part25and a further peripheral part26. The central part24faces the joining portion8. The peripheral part25faces the separation line4, in particular an end portion of the separation line4. More precisely, the peripheral part25faces the separation line4in a zone between the first end9of the separation line4and the end27of the incision line21. The further peripheral part26faces the separation line4, in particular a further end portion of the separation line4. More precisely, the further peripheral part26faces the separation line4in a zone between the second end10of the separation line4and the further end28of the incision line21.

Between the peripheral part25of the incision line21and a portion of the separation line4which starts from the first end9, a connecting band29is defined for connecting the joining portion8to the retaining ring5. Similarly, between the further peripheral part26of the incision line21and a further portion of the separation line4which starts from the second end10, a further connecting band30is defined for connecting the joining portion8to the retaining ring5

In the example illustrated, the connecting band29and the further connecting band30are arranged symmetrically to each other relative to a plane containing the axis Z and a centre line of the joining portion8.

The incision line21may be shaped as a through cut which passes through the entire thickness of the side wall2. Even though this feature is not shown inFIGS.1to3, along the incision line21there may be one or more breakable elements intended to break the first time the cap1is opened. Alternatively, the incision line21may be shaped as a weakening line that does not pass through the entire thickness of the side wall2, but at which the thickness of the side wall2is reduced with respect to the surrounding zones.

At the first end9and at the second end10of the separation line4, and/or at the end27and at the further end28of the incision line21, there may be incision zones38, shown inFIG.1. The incision zones38may have a circular geometry and in general have a transversal dimension greater than a width of the corresponding incision line or separation line. This makes it possible to prevent the propagation of fracture cracks starting from the incision or separation lines. In an alternative embodiment, the incision zones38may be absent.

In a central part of the joining portion8there may be a stress reduction cut39, having dimensions very limited relative to the dimensions of the joining portion8, so as to not adversely affect the resistance of the joining portion8. The stress reduction cut39makes it possible to increase the deformability of the central part of the joining portion8, reducing stresses in the surrounding zones. The presence of the stress reduction cut39is optional.

The cap1is applied on the neck18of the container in the closed position shown inFIG.1. The cap1is positioned in such a way that the engagement element20provided inside the retaining ring5is below the circular enlargement23present on the neck18.

When the user wishes to open the container for the first time, the user grips the skirt11of the closure element6and rotates the closure element6about the axis Z, in order to unscrew the closure element6from the neck18. Initially, the closure element6and the retaining ring5are rotated together about the axis Z, and they simultaneously move together in a direction parallel to the axis Z, away from the neck18. This occurs until the engagement element20of the retaining ring5abuts against the circular enlargement23provided on the neck18. At this point, the circular enlargement23prevents the retaining ring5from rising further along the axis Z, acting as a stop for the movement of the retaining ring5away from the neck18.

The closure element6, which is unscrewed by the user, continues to move along the axis Z away from the neck18. The breakable bridges7are thereby tensioned, until causing their failure. The closure element6consequently separates from the retaining ring5along the separation line4, but remains joined to the retaining ring5at the joining portion8.

If the user continues to unscrew the closure element6, so as to move the closure element6along the axis Z to remove it from the neck18, the first connecting band29and the second connecting band30deform. In particular, by moving the closure element6upwards, the first connecting band29and the second connecting band30are also pulled upwards. Consequently, the first connecting band29and the second connecting band30are spaced apart from both the closure element6and the retaining ring5and remain joined to each other in the joining portion8.

The first connecting band29and the second connecting band30thus adopt a kind of trapezium shape as shown inFIG.2, in which the neck18of the container is not shown. In this configuration, the first connecting band29remains joined to the retaining ring5at the end27of the incision line21. Similarly, the second connecting band30remains joined to the retaining ring5at the further end28of the incision line21.

The first connecting band29and the second connecting band30are joined to each other in the joining portion8.

In other words, the first connecting band29and the second connecting band30are arranged in an inclined configuration relative to the retaining ring5and converge in the joining portion8.

Continuing to unscrew the closure element6, the latter is disengaged from the outer thread17made on the neck18, so that the container can be opened. The retaining ring5remains, however, anchored to the neck18. The first connecting band29, the second connecting band30and the joining portion8define a hinge arrangement40, shown inFIG.3, about which the closure element6can rotate to allow the user to access the contents of the container.

In particular, by moving the closure element6about the hinge arrangement40after the closure element6has been disengaged from the neck18, it is possible to move the closure element6to a lateral position relative to the neck18, so that the closure element6is no longer coaxial with the retaining ring5, as shown inFIG.3. The closure element6may be rotated further backwards relative to the position shown inFIG.3, in order to move it further away from the neck18and to allow the user to more easily access the contents of the container.

After use, the user can return the cap1to the closed position shown inFIG.1by a sequence of operations in reverse order compared with that previously described.

The first connecting band29and the second connecting band30allow a hinge arrangement40to be obtained which is longer than that which would be available if only one hinge band defined by the joining portion8were present. This makes it easier to disengage the closure element6from the neck18, and reapply the closure element6on the neck18, by rotating the closure element6about the hinge arrangement40.

FIGS.4to6and9show a cap201according to another embodiment. The parts of the cap201common to the cap1described with reference toFIGS.1to3will be indicated with the reference numbers already used inFIGS.1to3and, for brevity, will not be described again in detail. What was previously described with reference to the cap1shall be understood to also be applicable to the cap201, unless differences are explicitly provided. As shown inFIGS.4to6and9, the cap201comprises the side wall2which extends about the axis Z, and the transversal wall3located at an end of the side wall2, so as to close that end.

The cap201is further provided with the separation line4, positioned on the side wall2, which defines on the cap201the retaining ring5and the closure element6. The retaining ring5is intended to remain anchored to the neck of the container on which the cap201is applied, owing to at least one engagement element provided inside it. In contrast, the closure element6is suitable for removably engaging with the neck, owing to the member for removably fixing provided inside the skirt11. In this way, the closure element6is movable between a closed position, shown inFIGS.4and5, and an open position, shown inFIG.9.

The separation line of4extends about the axis Z and is circumferentially interrupted so as to define on the side wall2the joining portion8by which the closure element6is joined to the retaining ring5.

The incision line21is furthermore provided on the side wall2. In the example illustrated, the incision line21is axially interposed between the free edge16of the retaining ring5and the separation line4.

The incision line21comprises a peripheral part25, a further peripheral part26and a central part24interposed between the peripheral part25and the further peripheral part26. The incision line21lies entirely in a plane positioned transversally, in particular perpendicularly, to the axis Z. In other words, the peripheral part25, the central part24and the further peripheral part26are positioned in a common plane arranged transversally, in particular perpendicularly, to the axis Z.

Two connecting bands, that is to say, a connecting band29and a further connecting band30, are defined between the separation line4and the incision line21, the two connecting bands joining the retaining ring5to the joining portion8.

In particular, the connecting band29extends between the peripheral part25of the incision line21and a portion of the separation line4which starts from the first end9of the later. Similarly, the further connecting band30extends between the further peripheral part26of the incision line21and a further portion of the separation line4which starts from the second end10. The connecting band29and the further connecting band30may be arranged symmetrically to each other relative to a plane containing the axis Z and a centre line of the joining portion8.

FIGS.7and8show a neck218on which the cap201may be applied. The neck218extends about a longitudinal axis Z1. When the cap201is applied on the neck218and the closure element6is in the closed position, the axis Z of the side wall2coincides with the longitudinal axis Z1.

The neck218is delimited by an outer surface219, which in the example illustrated is cylindrical and coaxial with the longitudinal axis Z1.

The outer surface219extends as far as a rim220of the neck218. The rim220surrounds an opening221through which it is possible to access the container, when the closure element6is in the open position. Vice versa, the closure element6closes the opening221when it is arranged in the closed position.

The neck218comprises a collar222, suitable for preventing the retaining ring5from descending along the neck218below a predetermined level. Moreover, the collar222may be used for conveying the container during the production, filling and capping process.

The outer surface219extends from the collar222to the rim220.

A circular enlargement223projects from the outer surface219, the circular enlargement223being suitable for engaging with the engagement element provided inside the retaining ring5so as to prevent the retaining ring5from being detached from the neck218.

The circular enlargement223may comprise a truncated cone shaped portion224, whose diameter increases in a direction going from the rim220towards the collar222.

The circular enlargement223is delimited, on the opposite side to the rim220, by an abutment surface225against which the at least one engagement element of the retaining ring5abuts.

A cylindrical portion of the circular enlargement223may be interposed between the truncated cone shaped portion224and the abutment surface225.

However, other geometries of the circular enlargement223are possible. The neck218comprises at least one element for removably fixing with which the member for removably fixing formed inside the closure element6can engage to allow the closure element6to be alternatively applied on, or removed from, the neck218.

The at least one element for removably fixing may comprise an outer thread217formed on the outer surface219, in particular projecting from the outer surface219.

The cap201is intended to be applied on the neck218when the closure element6is in the closed position. In particular, the cap201is applied on the neck218in such a way that the at least one engagement element provided inside the retaining ring5is below the circular enlargement223, in particular in a position interposed between the collar222and the circular enlargement223.

When the user acts on the cap201to move the closure element6to the open position for the first time, the closure element6is unscrewed, that is to say, it is rotated about the longitudinal axis Z1and simultaneously moved away from the collar222. The retaining ring5, joined to the closure element6by the breakable bridges7, initially moves together with the closure element6. When the at least one engagement element provided inside the retaining ring5abuts against the abutment surface225, the retaining ring5cannot rise any further along the neck218. On the other hand, the closure element6moves further away from the body of the container and simultaneously rotates about the longitudinal axis Z1, gradually as the user continues to unscrew the closure element6. In this way, the breakable bridges7arranged along the separation line4are subjected to a stress that causes them to break. The connecting bands29,30also deform while the closure element6is unscrewed. In particular, gradually as the closure element6, during unscrewing, is moved away from the retaining ring5, the connecting bands29,30are positioned in an inclined position relative to the retaining ring5, detaching from the retaining ring5along the incision line21. The closure element6also detaches from the connecting bands29,30. Any breakable elements positioned along the incision line21break.

In this way, the position shown inFIG.6is reached, wherein the neck has not been shown. The position shown inFIG.6may be defined as a disengaged position, because in the position shown inFIG.6the member for removably fixing formed inside the closure element6have disengaged from the thread217of the neck218.

At this point, the closure element6may be rotated relative to the retaining ring5for displacing it into the open position shown inFIG.9, in which the closure element6is arranged on one side of the neck218and the axis Z of the closure element6no longer coincides with the longitudinal axis Z1of the neck218.

The connecting bands29,30are deformable, in such a way that not just the closure element6, but also the joining portion8is rotated relative to the neck218.

As is shown more clearly inFIG.6, the joining portion8is delimited by an edge50which, in the closed position of the closure element6(and in general before the closure element6is rotated relative to the retaining ring5to be moved to the open position) faces the retaining ring5. More specifically, the edge50is defined on the side wall2, towards the closure element6, by the incision line21.

When the closure element6passes from the disengaged position to the open position, the joining portion8is overturned relative to the neck218. Consequently, the edge50, which in the disengaged position (and also in the closed position) was facing the retaining ring5, is positioned in such a way that it is facing towards the rim220of the neck218, that is to say, upwards in the operative condition ofFIG.9.

In order to make that possible, the joining portion8, and in particular its edge50, slides along the truncated cone shaped portion224of the circular enlargement223and simultaneously rotates relative to the connecting bands29,30. The edge50reaches a height which is higher than the circular enlargement223, assuming that the neck218is positioned in such a way that the opening221is facing upwards. The joining portion8is thus positioned at least partly above the circular enlargement223, resting on the neck218. In particular, the joining portion8rests on the outer surface219above the circular enlargement223.

In this way, an interference is generated between the neck218and the joining portion8, in particular along the edge50and near the latter. There may also be interference between the connecting bands29,30and the neck218. This allows the closure element6to be stably kept in the open position. In effect, in order to bring the closure element6back to the closed position, it is necessary to overcome the interference between the joining portion8and the neck218. Normally, that does not occur accidentally, instead only occurring if the user deliberately applies sufficient force to the closure element6, that is to say, if the user wishes to move the closure element6to the closed position.

Moreover, the interference which occurs between the joining portion8and the neck218makes it difficult for the cap201to be able to rotate about the neck218, due to the rotation of the retaining ring5about the neck218. In effect, the retaining ring5is connected to the joining portion8by the connecting bands29,30. Consequently, the retaining ring5is not free to rotate about the neck218, instead it can only rotate if the interference between the joining portion8and the neck218is overcome.

In order to make it possible for the joining portion8to rotate when the closure element6passes from the disengaged position to the open position, the connecting bands29,30are subjected to twisting, which affects at least part of the height H of each connecting band29,30. The term “height H” of the connecting bands29,30refers to the dimension of the connecting bands29,30in a direction parallel to the axis Z of the side wall2, when the closure element6is in the closed position, as shown inFIG.4.

In the example illustrated, wherein the separation line4and the incision line21lie in respective planes parallel to each other, the height H of the connecting bands29,30is constant along the entire length of the connecting bands29,30and is equal for the two connecting bands29,30. As shown inFIGS.4to6and9, the knurling lines13are provided on the closure element6. The knurling lines13may extend parallel to the axis Z. In the example illustrated, the separation line4intersects the knurling lines13. In other words, the knurling lines13extend on both sides of, that is to say, both above and below, the separation line4.

That occurs because the separation line4is provided in a position as close as possible to the member for removably fixing arranged inside the closure element6, that is to say, to the inner thread. In this way, it is possible to increase the height H of the connecting bands29,30.

Consequently, as shown inFIG.9, the connecting bands29,30comprise a first portion51adjacent to the separation line4, which in the example shown is provided with knurling lines13and a second portion52adjacent to the incision line21, which in the example shown is smooth. A widened part53may be provided between the first portion51and the second portion52.

In the example illustrated, when the joining portion8rotates so that the edge50is facing towards the rim220, the second portion52of the connecting bands29,30twists and passes under the first portion51. The first portion51, like the widened part53, if present, in contrast expands radially, but does not undergo substantial twisting.

Owing to deformation of the connecting bands29,30, the joining portion8can rest on the neck218with the edge50facing towards the rim220, without it being necessary to provide weakening lines or fracture lines in the joining portion8and/or in the connecting bands29,30. In this way, production of the cap201is not complicated.

In the closed position, when the edge50faces the retaining ring5, there is an albeit small amount of play between the joining portion8and the neck218. When the closure element6is moved to be brought to the open position, the joining portion8begins to rotate and starts to interfere with the neck218. The interference between the joining portion8and the neck218reaches a maximum value when the joining portion8is approximately arranged in a plane perpendicular, or almost perpendicular, to the neck218, or rather to its longitudinal axis Z1. The interference between the joining portion8and the neck218is reduced when the joining portion8is overturned, that is to say, when the edge50moves above the connecting bands29,30. In the open position, the interference between the joining portion8and the neck218remains, although it is less than the maximum value.

When the position in which the interference reaches a maximum value is passed, the user who is manually rotating the closure element6in order to move it to the open position can feel a sort of vibration. That vibration is perceived by the hand of the user, who is moving the closure element6, as a discontinuity in the movement of the closure element6. In other words, the closure element6snaps into place beyond the position in which the interference between the joining portion8and the neck218reaches the maximum value, and the user perceives this snap motion.

In this way the user is certain that the closure element6has been correctly moved to the open position.

It is also possible, but not necessary, for the vibration to be accompanied by a sound such as a “click”, which can be heard by the user.

The cap201described above guarantees not just that the closure element6stably remains in the open position, but also that, in the open position, the closure element6is rotated backwards, relative to the neck, by a relatively wide opening angle A2, as shown inFIG.9.

In particular, the angle A2may be greater than, or equal to, 140°. This makes it very difficult for the closure element6to be able in an unwelcome way to strike the face of the user who is drinking directly from the bottle on which the cap201is applied, or for the closure element6to be able to obstruct the dispensing of a liquid contained in the bottle into a container, such as a glass.

Experimentation has shown that several geometric parameters of the cap201and/or of the neck218favour the behaviour previously described with reference toFIG.9.

In particular, on the neck218it is possible to define an external or maximum diameter Dmax of the circular enlargement223, as shown inFIG.7. It is also possible to define a diameter Ds of the outer surface219of the neck218, immediately above the circular enlargement223, that is to say, in a position interposed between the circular enlargement223and the outer thread217. In the example illustrated, the diameter Ds immediately above the circular enlargement223coincides with the diameter of the outer surface219in a region interposed between the outer thread217and the rim220, but this condition is not necessary.

Delta indicates the difference between the external diameter Dmax of the circular enlargement223and the diameter Ds of the outer surface219immediately above the circular enlargement223.

In the example illustrated, the external diameter Dmax of the circular enlargement223is 30.2 mm.

The diameter Ds of the outer surface219immediately above the circular enlargement223is 28 mm.

The difference Delta between Dmax and Ds is 30.2−28=2.2 mm.

Half of the difference Delta expresses how far the circular enlargement223projects relative to the outer surface219.

As already said, H indicates the height of the connecting bands29,30, that is to say, the distance between the separation line4and the incision line21, measured parallel to the axis Z, when the closure element6is in the closed position.

In the example illustrated, the height H is 2.8 mm.

The ratio R1between the height H and half of the difference Delta is therefore 2.8/1.1, that is to say, 2.55.

It is advisable for the ratio R1between the height H and half of the difference Delta, as they are defined above, to be greater than, or equal to 1.5. It is preferable for the above-mentioned ratio R1to be greater than, or equal to, 2. It is even more preferable for R1to be greater than, or equal to, 2.5.

That ensures that the height H of the connecting bands29,30is correctly proportionate to how far the circular enlargement223projects from the outer surface219.

More specifically, if the ratio R1is less than 1.5, it may happen that between the joining portion8and the neck218the interference created is not sufficient to stably lock the closure element6in an open position in which the opening angle A2is greater than, or equal to, 120°, preferably greater than, or equal to, 140°.

In certain cases, a value of the ratio R1less than 1.5 can be accepted, but not less than 0.8.

In the example illustrated, half of the difference Delta between the external diameter Dmax of the circular enlargement223and the diameter Ds of the outer surface219of the neck218, immediately above the circular enlargement223, is Delta/2=1.1 mm.

It is possible to obtain a cap201which works correctly even with values of the difference Delta other than those mentioned above. In general, experimentation has shown that relatively low values of the difference Delta (and therefore of Delta/2) are helpful for obtaining a behaviour of the type shown inFIG.9.

The joining portion8has an angular dimension W about the axis Z of the side wall, which has been explicitly indicated inFIG.1and which is definable in the same way with reference to the cap201.

In the example illustrated, the angular dimension W of the joining portion8is 54°.

In general, the angular dimension W may be greater than, or equal to, 20°, preferably greater than, or equal to, 25°.

Moreover, the angular dimension W may be less than, or equal to, 120°, preferably less than, or equal to, 90°.

In an embodiment, the angular dimension W may be between 80° and 120°.

In an embodiment, the angular dimension W of the joining portion9may range from 30* to 110*. It may for example be 60°.

Experimentation has shown that, if the angular dimension W is greater than 120°, the connecting bands29,30may break, when the closure element6is rotated in order to move it to the open position.

In contrast, if W is less than 20°, it may happen that the joining portion8does not succeed in stably keeping the closure element6in an open position in which the opening angle A2is greater than, or equal to, 120°, preferably greater than, or equal to, 140°.

It is also possible to define a distance Y, shown inFIG.7, between the circular enlargement223and the at least one element for removably fixing provided on the neck219. In other words, the distance Y is measured between the upper limit of the circular enlargement223and the starting point of the outer thread217.

The distance Y may be greater than, or equal to, half of the distance between the separation line4and the incision line21, that is to say, half the height H. However, this condition is not necessary.

It is possible to define an angle A, indicated inFIG.7, formed between a generatrix of the truncated cone shaped portion224and a straight line parallel to the longitudinal axis Z1.

In the example illustrated, the angle A is 30°.

More generally, the angle A is preferably less than, or equal to, 35°.

That reduces the risk of the joining portion8not sliding correctly on the circular enlargement223, in particular near the external diameter Dmax, for then stably stopping in contact with the neck218.

When the user wishes to reclose the container, the closure element6can be returned to the closed position with a sequence of operations in reverse order compared with that previously described. In particular, the user rotates the closure element6relative to the neck218in order to return it to the closed position. Consequently, the joining portion8is also rotated, so as to return the edge50below the connecting bands29,30, in a position facing the retaining ring5. When the edge50disengages from the neck218, the user perceives a vibration or snap-motion feedback, which may (but not necessarily) be accompanied by a “click” sound. In this way, the user realises that the closure element6is ready to be screwed onto the neck218again. In effect, the disengagement position has been reached, starting from which the closure element6can be screwed onto the neck218again for moving it to the closed position.

In the example ofFIG.9, in the open position, the edge50lies in a plane substantially perpendicular to the longitudinal axis Z1of the neck218, that is to say, in a horizontal plane. However, this condition is not necessary.

As shown inFIG.10, in the open position, the edge50could also lie on a plane inclined towards the outer surface219of the neck218, on the side of the rim22.

In the open position, the edge50could also adopt a configuration similar to that ofFIG.10, but not flat.

Also in the case shown inFIG.10, the behaviour of the cap is similar to that described above with reference toFIGS.4to6and9. What has been described with reference toFIGS.4to6and9is therefore to be considered also applicable toFIG.10.

In the example described so far with reference toFIGS.4to6and9, the separation line4is located in a portion of the side wall2wherein the knurling lines13are present.

However, this condition is not necessary. In an alternative embodiment not illustrated, the separation line4may be made in a portion of the side wall2wherein the latter is externally delimited by a substantially smooth outer surface. That is to say, the separation line4may be positioned in a portion of the side wall2free of knurling lines13, for example interposed between the knurling lines13and the free edge16. Consequently, in the alternative embodiment just described, the connecting bands29,30are externally delimited by a smooth surface, that is to say, a surface free of knurling lines. An example of a cap of this type is shown inFIG.11.

FIG.11shows a cap301in which the side wall2has, on an outer surface thereof, a plurality of knurling lines13.

In the example ofFIG.11, the separation line4is provided in a portion of the side wall2without knurling lines13, that is to say, in a smooth portion of the side wall2. This occurs because the knurling lines13have respective lower ends (that is to say, closer to the free edge16) which are spaced from the separation line4. The separation line4is therefore provided in a non-knurled portion of the side wall2.

The breakable bridges7arranged along the separation line4are visible in the example ofFIG.11. Some breakable elements70arranged along the incision line21are also visible. The breakable elements70may be similar to the breakable bridges7.

In the example shown, the breakable elements70are offset relative to the breakable bridges7, in a direction parallel to the axis Z of the cap301. In other words, a plane which contains the axis Z and passes through a breakable bridge7does not intersect any breakable element70.

In other words, the breakable elements70are arranged in positions angularly offset about the axis Z relative to the breakable bridges7.

Each breakable bridge7and each breakable element70may have a width, measured in a circumferential direction, respectively, along the separation line4and along the incision line21, equal to 0.4 mm.

The cap301shown inFIG.11has, during opening and closing, a behaviour similar to that of the cap201shown inFIGS.4to6and9. More specifically, when the closure element6of the cap301is moved from the closed position to the open position, the connecting bands29,30deform with a twisting movement which may affect a part of their height, similarly to what is shown inFIGS.9and10for the cap201. In the example ofFIG.11, the first portion51adjacent to the separation line4and the second portion52adjacent to the incision line21are both smooth, that is to say, without knurling lines.

The connecting bands29,30shown inFIG.11can be deformed in such a way that the first portion51expands radially, without undergoing a substantial twisting. The second portion52, on the other hand, may twist to pass under the first portion51, so as to be interposed between the first portion51and the outer surface219of the neck218. In this way, the edge50may pass beyond the circular enlargement223and be positioned at a height higher than the latter, that is to say, closer to the rim220than the circular enlargement223.

This allows the joining portion8to rotate relative to the connecting bands29,30, thereby passing above, that is to say, at a higher height, of the circular enlargement223and resting on the outer surface219.

As shown inFIG.11, the separation line4is positioned at a distance D1from the free edge16of the retaining ring5.

The distance D1is less than, or equal to, 6.5 mm. Preferably, the distance D1is less than, or equal to, 5 mm.

The distance D1is greater than, or equal, to 2 mm. Preferably, the distance D1is greater than, or equal to, 3 mm.

In a preferred embodiment, the distance D1is thus between 3 and 5 mm. The separation line4may have an angular extension, about the axis Z, greater than, or equal to, 250°. The angular extension of the separation line4may be less than, or equal to, 330°.

In an embodiment, the angular extension of the separation line4may be between 250° and 280°.

The incision line21is positioned at a distance D2from the free edge16of the retaining ring5.

The distance D2may be greater than, or equal to, 1 mm.

The distance D2may be less than, or equal to, 5 mm. More specifically, the distance D2may be less than, or equal to, 4 mm.

In an embodiment, the distance D2may be between 1 and 3 mm.

In an embodiment, the distance D2may be equal to 3.9 mm.

The incision line21may have an angular extension about the axis Z greater than, or equal to, 120°. This angular extension may be less than, or equal to, 250°.

In an embodiment, the incision line21may have an angular extension greater than, or equal to, 130°.

The angular extension of the incision line21may be less than, or equal to, 200°.

The angular extension of the incision line21may be, for example, equal to 160°.

In an embodiment, the angular extension of the incision line21may be between 180° and 250°.

The connecting bands29,30may have a height H greater than, or equal to, 1 mm and less than, or equal to, 5.5 mm.

The height H is measured parallel to the axis Z, in the closed position of the cap1.

More specifically, the connecting bands29,30may have a height H greater than, or equal to, 1.2 mm and less than, or equal to, 4 mm.

In an embodiment, the height H ranges from 1.2 mm to 3.5 mm.

The height H may be equal to 2 mm.

In an embodiment, the cap301may have a height H1, measured in a direction parallel to the axis Z, between 10 and 21 mm.

As shown inFIG.12, each connecting band29,30may have a radial thickness S, that is to say, a thickness measured in a radial direction relative to the axis Z, greater than, or equal to, 0.35 mm. This thickness may be less than, or equal to, 1.8 mm.

In an embodiment, the radial thickness S of each connecting band29,30may be greater than, or equal to, 0.5 mm. This thickness may be less than, or equal to, 1.2 mm.

The radial thickness S of the connecting bands29,30may be constant in a direction parallel to the axis Z. Alternatively, the radial thickness S of the connecting bands29,30may be variable in a direction parallel to the axis Z. More specifically, the radial thickness S of the connecting bands29,30may vary along a direction parallel to the axis Z, in such a way as to remain inside the ranges indicated above.

In an embodiment, relatively large radial thicknesses S of the connecting bands29,30correspond to a relatively small height H, and vice versa.

For example, if the radial thickness S is in the upper half of the range 0.35-1.8 mm, that is to say, in the range 1.1-1.8 mm, the height H may be in the lower half of the range 1-5.5 mm, that is to say, in the range 1-3.2 mm.

The opposite also applies, that is to say, if the radial thickness S is variable in the range of 0.35-1.1 mm, the height H may be variable in the range 3.2-5.5 mm. It is, however, also possible to combine relatively large radial thicknesses S of the connecting bands29,30with a relatively large height H.

Below are some examples of dimensions which caps of the type shown inFIG.11may have.

Type of cap/neckS [mm]H [mm]H/S29/25 mm0.71.21.7129/25 mm0.72.33.29PCO 18810.753.54.6730/25 mm0.652.74.1530/25 mm0.452.455.4438 mm 3 threads0.73.14.4329/25 mm0.851.21.430/25 mm0.552.85.1

It has been found experimentally that these caps remain stably open with an opening angle A2of at least 120°.

The ratio between the height H of the connecting bands (that is to say, the distance between the separation line4and the incision line21) and the radial thickness S of the connecting bands may be greater than, or equal to, 1.4.

The above-mentioned ratio may be less than, or equal to, 5.1.

More generally speaking, the ratio between the height H of the connecting bands and the radial thickness R of the connecting bands may be less than, or equal to, 6.5.

These values ensure that the connecting bands29,30have an optimum torsional rigidity to deform as described above and to generate an interference between the neck and the joining portion8(and possibly between the neck the connecting bands29,30) sufficient to keep the closure element6in the open position in a reliable and secure manner.

The numerical values defined above with reference to the cap301shown inFIG.11are also applicable to the cap201shown inFIGS.4to6,9and10.

The cap201or301is also particularly easy to make.

In effect, the cap201or301may be obtained starting from a concave body comprising the side wall2and the transversal wall3. The concave body is produced by moulding a polymeric material, for example compression moulding or injection moulding.

After the concave body has been formed, the separation line4and the incision line21are made on the side wall2.

The separation line4and the incision line21may be made by cutting operations, for example performed in a cutting unit located downstream of a mould in which the concave body has been formed. Such cutting operations may be performed by respective blades, for example circular or linear, which interact with the side wall2from the outside of the latter, or from the inside. In particular, the concave body may be rotated about the axis Z of the side wall2, while the blades are held in their position, so as to bring consecutive zones of the side wall2to interact, one after another, with the blades. It is also possible to hold the concave body in its position and to rotate the blades, for making the cut.

The blades which allow the separation line4and the incision line21to be obtained may be configured to interact with the side wall2in respective parallel planes, for example perpendicular to the axis Z, if, as in the examples shown so far, the separation line4and the incision line21are to lie in respective parallel planes.

The blades may have an interrupted cutting edge, if, along the separation line4the breakable bridges7are to remain defined and/or if, along the incision line21, respective breakable elements are to remain defined.

The incision line21may be made by using a blade having a flat cutting edge, so that the incision line21lies in a plane for the whole length of the incision line21.

It is also possible that the blades do not cut through the entire thickness of the side wall2, instead only partially cutting through thickness of the side wall2, so as to leave, along the incision line21and/or along the separation line4, a thin membrane intended to be broken the first time the cap is opened.

The separation line4and the incision line21may be made simultaneously, or during two separate steps.

The cap201or301is therefore particularly easy to produce, since the concave body can be formed in an ordinary mould. There is no need for undercut parts or thin parts other than those normally provided for a cap of the known type.

An additional operation, that is to say, making the incision line21, may be performed very simply while the separation line4is obtained.

Geometries of the incision line different from those that have been shown so far are possible.

For example,FIG.13shows a cap401according to an alternative embodiment, which differs from that shown inFIG.11because it comprises an incision line421which does not lie in a single plane, but is defined by two curved stretches421aand421bwhich lie in respective planes converging in a common line. That is to say, the curved stretches421a,421bconverge at a point P which, in the example ofFIG.13, is positioned higher than the remaining extension of the curved stretches421a,421b.

The example ofFIG.15shows, on the other hand, a cap601the incision line621of which is defined by two curved stretches621a,621bwhich converge at a point P1positioned lower than the remaining extension of the curved stretches621a,621b.

In the example ofFIG.14, on the other hand, there is provided a cap501having an incision line521which is not flat, but which has a curved trend on the side wall of the cap, with concavity facing downwards, that is, towards the free edge16of the retaining ring5.

Lastly,FIG.16shows a cap701the incision line721of which has a curved shape with concavity facing upwards, that is to say, towards the closure element6.

The caps described above are made of plastics, for example polypropylene (PP) or polyethylene (PE).

If PE is used, its density may range from low density to high density. More specifically, it is possible to use high-density polyethylene (HDPE).

The high-density polyethylene (HDPE) used to produce the caps described above can have the following properties:a density variable between 950 and 968 kg/m3;melt index variable from 0.3 to 20 g, under the following measurement conditions: 10 minutes, 190° C., 2.16 kg;large, or narrow, or unimodal, or multi-modal distribution of molecular weight.

If PP is used, the material may be in the form of a homopolymer, or heterophasic copolymer, or statistical copolymer.

The melt index of the PP may vary from 2 to 20 g, under the following measurement conditions: 10 minutes, 230° C., 2.16 kg.