A LID FOR CLOSING A CONTAINER, A COMBINATION OF A LID AND A NECK

Abstract

A lid for a container comprises a side wall (2) extending about an axis (Z) and a cross wall (3) disposed at one end of the side wall (2); a parting line (4) is provided in the side wall (2) to define: - a retaining ring (5) intended to remain anchored to a neck (18; 218) of the container, and - a closure element (6) detachably attachable to the neck (18; 218) for opening or closing the container; the parting line (4) extends about the axis (Z) and is circumferentially interrupted to leave a joining portion (8) between the retaining ring (5) and the closure element (6); the lid (1;201) further has a slit line (21) extending transversely to the (Z) axis between the parting line (4) and a free edge (16) of the retaining ring (5), such that between the parting line (4) and the slit line (21) two connecting bands (29, 30) are defined, the connecting bands (29, 30) joining the retaining ring (5) to the joining portion (8); the connecting bands (29, 30) have a radial thickness measured in a radial direction and a height (H) measured parallel to the (Z) axis; the ratio of the height (H) to the radial thickness of the connecting bands (29, 30) is greater than or equal to 1.4 and less than or equal to 6.5.

Description

This invention relates to a lid for a container, in particular a lid having a retaining ring, which can be associated with a neck of the container, the lid further having a locking element which, after opening, remains connected to the retaining ring. The lid according to the invention is particularly, but not exclusively, suitable for use on bottles intended to contain liquid substances. The invention also relates to a combination of a lid and a neck of a container. Furthermore, the invention relates to a method for producing a lid for a container. Bottle caps are known, comprising a cup-shaped body with an internal thread suitable for engaging with an external thread on a bottle neck. These caps are further provided with a tamper-evident ring connected to the cup-shaped body by means of a plurality of breakable elements. When the cap is first opened, the cup-shaped body separates from the tamper-evident ring due to the breakage of these breakable elements. The tamper-evident ring remains attached to the bottle neck, while the user can unscrew the cup-shaped body, thereby separating it from the bottle to access the contents. Subsequently, the cup-shaped body can be screwed back onto the neck to reseal the bottle. Sometimes, after emptying the bottle, the user throws the cup-shaped body to the ground, intentionally or accidentally, while the bottle, along with its associated safety ring, is properly disposed of in a trash container. To overcome this problem, caps have been proposed that are equipped with a retaining ring, which can be attached to a bottle neck, and a locking element connected to the retaining ring by a hinge. The locking element can be rotated around the hinge between an open position, in which a user can access the bottle's contents, and a closed position, in which the locking element prevents access to the bottle. The hinge keeps the locking element attached to the retaining ring and, therefore, to the bottle, thus preventing the locking element from being thrown to the ground independently of the bottle. However, lids with hinges have the drawback of being quite complicated to manufacture. In fact, the hinge is usually produced in the same mold as the lid, particularly by injection molding or compression molding. Therefore, to manufacture lids with a known type of hinge, it is necessary to use special molds, different from those normally used to manufacture lids without a hinge. These molds are more complex than ordinary ones, particularly because lids with a known type of hinge may have undercut sections, requiring special means for their removal from the mold. Furthermore, known types of hinged lids can have areas of very reduced thickness, which are difficult to obtain because the molten polymer material flows with difficulty in the portions of the mold intended to form these areas. This increases the production costs of hinged lids and / or the cycle time required to obtain them. In hinged caps of the common type, the locking element, after being moved to the open position, sometimes closes prematurely again as it rotates around the hinge. It can also happen that the locking element rotates partially around the hinge, moving into a vertical or near-vertical position. In these cases, the locking element may unintentionally strike the face of a user drinking from the bottle to which the hinged cap is attached, or it may become positioned between the bottle and a container, such as a glass, into which liquid from the bottle is being poured. Furthermore, in hinged caps of the known type, when the locking element has been moved to the open position, the retaining ring, which remains attached to the neck, can rotate freely around the neck itself. Therefore, it can happen that while a user is drinking from the bottle with the hinged cap, or while pouring the liquid from the bottle into a glass, the retaining ring rotates around the neck due to gravity, along with the locking element. If this occurs, the locking element can strike the face of the person drinking, or become lodged between the neck of the bottle and the glass, obstructing the flow of the liquid into the glass. An object of the invention is to improve lids of a known type, in particular lids comprising a retaining ring intended to remain associated with a container neck and a locking element that can be detachably fitted to the neck to allow a user to open or alternatively close the container. Another objective is to provide a lid for a container, of the type mentioned above, which can be easily produced. Another objective is to provide a lid for a container, provided with a closing element that remains connected to the retaining ring, which does not require very complicated molds for its production. Another object is to provide a lid for a container, comprising a closing element that remains connected to the retaining ring, wherein the closing element is held stable in an open position. Another objective is to provide a lid for a container in which, in the open position, there is a reduced risk of the closing element accidentally striking the user's face or obstructing the dispensing of a substance contained in the container into a glass or the like. In a first aspect of the invention, a combination of a lid for a container and a neck of a container is provided, wherein the neck is delimited by an outer surface from which a circular extension projects, the outer surface extending to an edge of the neck, and wherein the lid comprises a side wall extending about an axis, a parting line being provided in the side wall to define: a retaining ring intended to engage with the circular extension to remain anchored to the neck, and a locking element that can be detachably attached to the neck to allow movement between a closed and an open position, wherein the parting line extends around the axis and is interrupted circumferentially to leave a joining portion between the retaining ring and the locking element, wherein the cap further has a slit line extending transversely to the axis between the parting line and a free edge of the retaining ring, such that two connecting bands are defined between the parting line and the slit line, the two connecting bands joining the retaining ring to the joining portion, and wherein the connecting bands are deformable to allow the joining portion to rotate when the locking element is moved from the closed to the open position,so that an edge of the joining portion that, in the closed position, faces the retaining ring, is facing the edge of the neck in the open position. Due to this aspect of the invention, it is possible to obtain a lid capable of remaining stably in the open position. Indeed, when the connecting portion rotates while the closing element moves from the closed to the open position, interference occurs between the connecting portion and the neck of the container. This interference persists even in the open position. To return the closing element to the closed position, a predetermined force must be applied to the closing element to overcome the interference between the neck and the connecting portion. This makes it difficult, if not impossible, for the closing element to return to the closed position on its own. In more detail, in the open position, the connecting portion rests on the neck of the vessel, and the deformed connecting bands apply a force to the connecting portion, tending to keep it in contact with the vessel neck. This causes interference between the connecting portion and the vessel neck, stably holding the closure element in the open position. Due to the interference between the joining portion and the neck, the rotation of the cap, particularly the retaining ring, around the neck is also obstructed. In one embodiment, the connecting bands are deformable by means of a torsional movement when the closing element moves from the closed position to the open position. This torsional movement can affect at least part of the height of each connecting strip, the height being defined as the dimension of the connecting strip in a direction parallel to the axis, in the closed position of the closing element. This makes it possible to rotate the joining portion as described above, without introducing fracture lines or weakening between the joining portion and the connecting bands. Consequently, the production of the cap is simplified. As the joining portion rotates and its edge slides into contact with the neck until it reaches the open position where the edge of the joining portion is oriented towards the edge of the neck, interference is generated between the joining portion and the neck, which reaches a maximum value when the joining portion is substantially perpendicular to the neck, and which decreases (but does not reach a zero value) after the joining portion has been turned over and rests on the neck with the edge facing upwards. The user who moves the locking mechanism to the open position notices that it has passed the point of maximum interference, as their hand perceives a kind of vibration that indicates the mechanism has moved securely into the open position. This is welcome news for the user, who is then certain that they have opened the container correctly. In a second aspect of the invention, a combination of a lid for a container and a neck of a container is provided, wherein the neck is delimited by an outer surface from which a circular extension projects, the outer surface extending to a rim of the neck, the rim facing upwards in an operating condition, and wherein the lid comprises a side wall extending about an axis, a parting line being provided in the side wall to define: a retaining ring intended to engage with the circular extension to remain anchored to the neck, and a locking element that can be detachably attached to the neck to be movable between a closed position and an open position, wherein the parting line extends around the axis and is interrupted circumferentially to leave a joining portion between the retaining ring and the locking element, the cap further having a slit line extending transversely to the axis between the parting line and a free edge of the retaining ring, such that two connecting bands are defined between the parting line and the slit line, the two connecting bands joining the retaining ring to the joining portion, the connecting bands being deformable by a torsional movement affecting at least a portion of the height of each connecting band,so that the joining portion rotates relative to the connecting bands when the closing element moves from the closed position to the open position, and an edge of the joining portion which, in the closed position, faces the retaining ring, is placed at least in a central part of it above the circular enlargement, an interference between the joining portion and thus generating the neck that holds the closing element in the open position. Due to the second aspect of the invention, it is possible to prevent the locking element from prematurely returning to the closed position. Furthermore, the interference between the joining portion and the neck, and possibly also between the connecting bands and the neck, prevents the retaining ring from rotating freely around the neck when the lid is open, along with the locking element connected to it. In a third aspect of the invention, a combination of a lid for a container and a neck of a container is provided, wherein the neck is delimited by an outer surface from which a circular extension projects, the outer surface extending to a rim of the neck, and wherein the lid comprises a side wall extending around an axis, a parting line being provided in the side wall to define: a retaining ring intended to engage with the circular extension to remain anchored to the neck, and a locking element that can be detachably attached to the neck to be movable between a closed position and an open position, wherein the parting line extends around the axis and is interrupted circumferentially to leave a joining portion between the retaining ring and the locking element, the cap further having a slit line extending transversely to the axis between the parting line and a free edge of the retaining ring, such that between the parting line and the slit line two connecting bands are defined, the connecting bands joining the retaining ring to the joining portion, wherein each connecting band comprises a first portion adjacent to the parting line and a second adjacent portion up to the slit line,the first portion being configured to expand radially so that the second portion twists, passing underneath the first portion, when the closing element moves from the closed position to the open position. The deformation of the connecting bands in the third aspect of the invention generates an interference between the joining portion and the neck of the container, which allows the closing element to be stably held in the open position. In one embodiment of the foregoing aspects of the invention, the distance between the parting line and the incision line is equal to or greater than 0.8 times half the difference between the external diameter of the circular enlargement and the diameter of the external surface of the neck, immediately above the circular enlargement. More specifically, the distance between the parting line and the incision line is equal to or greater than 1.5 times half the difference between the external diameter of the circular enlargement and the diameter of the outer surface of the neck, immediately above the circular enlargement. The aforementioned distance is measured parallel to the axis of the side wall when the closing element is in the closed position. Therefore, this distance corresponds to the height of the connecting strips. Experimentation has shown that the distance values ​​between the parting line and the incision line mentioned above ensure that the connecting bands deform correctly when the fastener moves from the closed to the open position. Specifically, if the distance between the parting line and the incision line meets the condition specified above, an interference condition is created between the joining portion and the neck, which is highly beneficial for maintaining the fastener in the open position. It is preferable that the distance between the parting line and the incision line be equal to or greater than 2 times half the difference between the external diameter of the circular enlargement and the diameter of the external surface of the neck, immediately above the circular enlargement. It is even more preferable that the distance between the parting line and the incision line be equal to or greater than 2.5 times half the difference between the external diameter of the circular enlargement and the diameter of the external surface of the neck, immediately above the circular enlargement. In a fourth aspect of the invention, a combination of a lid for a container and a neck of a container is provided, wherein the neck is delimited by an outer surface from which a circular extension projects, the outer surface extending to an edge of the neck, and wherein the lid comprises a side wall extending about an axis, a parting line being provided in the side wall to define: a retaining ring intended to engage with the circular extension to remain anchored to the neck, and a locking element that can be detachably attached to the neck to be movable between a closed position and an open position, wherein the parting line extends around the axis and is interrupted circumferentially to leave a joining portion between the retaining ring and the locking element, the cap further having a slit line extending transversely to the axis between the parting line and a free edge of the retaining ring, such that two connecting bands are defined between the parting line and the slit line, the two connecting bands joining the retaining ring to the joining portion, and wherein a distance between the parting line and the slit line is equal to, or greater than, 0.8 times half the difference between an external diameter of the circular enlargement and a diameter of the outer surface of the neck immediately above the circular enlargement, said distance preferably being equal to or greater than 1.5 times half of said difference. In the combination according to the fourth aspect of the invention, there is an interference condition between the joining portion and the neck that is very favorable for keeping the closing element in the open position. In one embodiment of the foregoing aspects of the invention, the joining portion has an angular dimension around the axis of the side wall, greater than or equal to 20°, preferably greater than or equal to 25°. In one embodiment of the foregoing aspects of the invention, the joining portion has an angular dimension about the axis of the side wall that is less than or equal to 120°, preferably less than or equal to 90°. In this way, the joining portion is not too wide around the axis of the side wall, which would make it difficult for the joining portion to tip over, that is, for its edge to move from a configuration facing the retaining ring to a configuration facing the neck flange. At the same time, the joining portion is not too narrow around the axis of the side wall, which could create interference between the joining portion and the neck, which is not enough to keep the closing element stable in the open position. In one embodiment of the foregoing aspects of the invention, the collar is provided with at least one fastening element suitable for coupling with the closure element to allow the closure element to be detachably attached to the collar. The at least one fastening element may comprise a thread having one or more starts. Preferably, but not necessarily, the distance between the circular enlargement and the at least one fixing element is greater than or equal to half the distance between the parting line and the incision line. In this way, between the circular widening and the at least one fixing element there is sufficient space to receive the joining portion, without the edge of the latter interfering with the at least one fixing element. In one embodiment of the foregoing aspects of the invention, the circular widening is delimited, towards the rim of the neck, by a surface in the shape of a truncated cone. In one embodiment of the foregoing aspects of the invention, a generatrix of the truncated cone-shaped surface forms an angle less than or equal to 35° with a straight line parallel to a longitudinal axis of the neck. Preferably, the angle mentioned above is 30°. In this way, the locking element can be easily placed in an open position where it forms a sufficiently large opening angle with the neck. In one embodiment of the foregoing aspects of the invention, the parting line extends into a portion of the side wall in which a plurality of knurling lines are provided. In other words, the parting line intersects with the knurling lines provided on the side wall of the lid. This allows maximizing the height of the connecting bands, without compromising the ability of a user or capping machine to grip the cap. Alternatively, the parting line can extend into a portion of the side wall bounded externally by a smooth surface, i.e., a surface free of knurling lines. In a fifth aspect of the invention, a lid for a container is provided, comprising a side wall extending around an axis and a cross wall disposed at one end of the side wall, a parting line being provided in the side wall to define: - a retaining ring intended to remain anchored to a neck of the vessel, and - a closing element that can be detachably attached to the neck, to open or close the container; where the parting line extends around the axis and is interrupted circumferentially to leave a joining portion between the retaining ring and the closing element, the cap further having a slit line extending transversely to the axis between the parting line and a free edge of the retaining ring, such that two connecting bands are defined between the parting line and the slit line, the two connecting bands joining the retaining ring to opposite end areas of the joining portion. The connecting portion keeps the closure securely attached to the retaining ring and, therefore, to the neck of the container. This prevents the closure from being discarded separately from the container. This increases the likelihood that the closure, along with the container, will be disposed of correctly with similar waste, particularly plastic waste. The lid according to the fifth aspect of the invention can be produced relatively easily, without the need for special molds. In fact, the lid according to the fifth aspect of the invention can be produced in a conventional mold if the incision line is made by a cutting operation. This cutting operation can produce an incision line that extends through the entire thickness of the side wall, or an incision line that does not extend through it, in which the thickness of the side wall is only partially cut. It is also possible to create the incision line by molding, within the mold used to produce the cap, without causing excessive complications to the mold, due to the particularly simple shape of the incision line. In this case, the incision line can even be shaped like a weakening line. Since the incision line is located between the parting line and the free edge of the retaining ring, the incision line does not weaken the joining portion. In the cap according to the invention, the joining portion is therefore relatively robust, making accidental separation of the retaining ring from the closing element difficult. The connecting bands, together with the joining portion, define a hinge arrangement that has a range of motion, in an axial direction, notably greater than the range of motion that the joining portion alone would allow. Indeed, this hinge arrangement allows the locking element to be moved away from the retaining ring over a significant axial distance, determined by the combined length of the connecting bands and the joining portion. This allows the locking element to be easily disengaged from the neck of the vessel. In one embodiment, the joining portion has an angular dimension around the side wall axis greater than or equal to 20°, preferably greater than or equal to 25°. In one embodiment, the joining portion has an angular dimension around the side wall axis that is less than or equal to 120°, preferably less than or equal to 90°. This allows the joining portion to rotate when the locking element moves from a closed to an open position, so that an edge of the joining portion, which faces the retaining ring in the closed position, is oriented toward a flange of the neck in the open position. In this way, it is possible to obtain the advantages described above with reference to the first aspect of the invention, particularly with regard to the locking element remaining stable in the open position. In one embodiment, the connecting strips can be arranged symmetrically with respect to a plane containing the axis of the side wall and a centerline of the joining portion. This symmetrical shape allows for a reduction of involuntary movements of the closing element when the lid is in the open position, limiting in particular its lateral movements. In one modality, the joining portion has a substantially constant thickness in a plane containing the parting line. This makes the lid according to the fifth aspect of the invention even simpler to make, since no special molds are needed to produce triangular hinges or very thin joining lines. In a sixth aspect of the invention, a lid for a container is provided, comprising a side wall extending around an axis and a cross wall disposed at one end of the side wall, a parting line being provided in the side wall to define: - a retaining ring intended to remain anchored to a neck of the vessel, and - a closing element that can be detachably attached to the neck, to open or close the container; where the parting line extends around the axis and is interrupted circumferentially to leave a joining portion between the retaining ring and the closing element, the cap further having a slit line extending transversely to the axis between the parting line and a free edge of the retaining ring, such that two connecting bands are defined between the parting line and the slit line, the connecting bands joining the retaining ring to the joining portion, the connecting bands having a radial thickness measured in a radial direction with respect to the axis, the connecting bands further having a height measured parallel to the axis, and where the ratio between the height and the radial thickness of the connecting bands is greater than or equal to 1.4, said ratio being less than or equal to 6.5. These values ​​for the ratio between the height and radial thickness of the connecting strips ensure that the connecting strips have optimal torsional rigidity to withstand a torsional movement such that the connecting portion rotates relative to the connecting strips and rests on the neck above the circular extension. This creates an interference fit between the neck and the connecting portion, sufficient to reliably and securely hold the locking element in an open position. In a seventh aspect of the invention, a lid for a container is provided, comprising a side wall extending around an axis and a cross wall disposed at one end of the side wall, a parting line being provided in the side wall to define: - a retaining ring intended to remain anchored to a neck of the vessel, and - a closing element that can be detachably attached to the neck, to open or close the container; where the parting line extends around the axis and is interrupted circumferentially to leave a joining portion between the retaining ring and the closing element, the lid further having a slit line extending transversely to the axis between the parting line and a free edge of the retaining ring, such that two connecting bands are defined between the parting line and the slit line, the connecting bands joining the retaining ring to the joining portion, the slit line and the parting line being cutting lines, wherein along the parting line a plurality of breakable bridges are provided, along the slit line a plurality of breakable elements are provided, the breakable bridges and the breakable elements being intended to break the first time the lid is opened, wherein the slit line comprises a peripheral part,an additional peripheral part and a central part interposed between the peripheral part and the additional peripheral part, and where the incision line lies in a plane arranged perpendicular to said axis. In an eighth aspect of the invention, a method is provided comprising the steps of: producing a lid for a container, the lid comprising a side wall extending around an axis and a transverse wall disposed at one end of the side wall, providing a parting line in the side wall to define a retaining ring intended to remain anchored to a neck of the container, and a closure element that can be detachably attached to the neck, to open or close the container, wherein the parting line extends around the axis and is circumferentially interrupted to leave a joining portion between the retaining ring and the closure element, making an incision line extending transversely to the axis, so that two connecting bands are defined between the parting line and the incision line, the two connecting bands joining the retaining ring to the joining portion. The method according to the eighth aspect of the invention allows obtaining, in a particularly simple way, a lid in which the closing element is associated with the retaining ring. In one modality, the parting line and the incision line are made by cutting. The invention can be better understood and implemented with reference to the accompanying drawings which illustrate some non-limiting exemplary embodiments thereof and in which: Figure 1 is a perspective view of a lid for a container, in a closed position; Figure 2 is a side view of the lid of Figure 1, in a configuration in which a lid closing element is separated from a retaining ring; Figure 3 is an interrupted perspective view of the lid of Figure 1, applied to a neck of a container, in a configuration in which a closing element of the lid is moved to a lateral position with respect to the neck; Figure 4 is a side view showing a lid for a container, according to an alternative embodiment; Figure 5 is a view like that of Figure 4, from the direction D indicated in Figure 4; Figure 6 is a side view like that in Figure 4, in a configuration where a lid closing element is separated from a retaining ring; Figure 7 is a side view of a neck onto which the cap of Figure 4 can be screwed; Figure 8 is a perspective view of the neck in Figure 7; Figure 9 is a side view, showing the lid of Figure 4, applied over the neck of Figure 7, with the lid's closing element in an open position; Figure 10 shows an enlarged detail like that of Figure 9, highlighting a different behavior of the lid; Figure 11 is a view like that of Figure 4, showing a lid according to an alternative modality; Figure 12 is a cross-section of an enlarged detail of the lid in Figure 11; Figure 13 is a view like that of Figure 4, showing a lid according to another alternative configuration; Figure 14 is a view like that of Figure 4, showing a lid according to another alternative configuration; Figure 15 is a view like that of Figure 4, showing a lid according to another alternative configuration; Figure 16 is a view like that of Figure 4, showing a lid according to another alternative modality. Figure 1 shows a cap 1 for closing a container, particularly a bottle intended to hold a liquid substance such as a beverage. Cap 1 is made of polymeric material. Any suitable polymeric material can be used to mold Cap 1. Lid 1 is shown in Figure 1 in a closed position, the position it assumes as it comes off a lid production line, ready to be fitted to the container. In this state, lid 1 comprises a side wall 2 extending around a Z-axis, and a cross wall 3 arranged at one end of side wall 2 to close that end. The cross wall 3 extends transversely, specifically perpendicularly, to the Z-axis. The cross wall 3 can be flat, although other shapes are theoretically possible. In the illustrated example, the cross wall 3 is substantially circular in plan view. The cover 1 has a parting line 4, located on the side wall 2 and extending around the Z-axis. The parting line 4 extends in a plane arranged transversely, specifically perpendicular to the Z-axis. The parting line 4 defines a retaining ring 5 and a locking element 6 on the cover 1. These are located on opposite sides of the parting line 4. As described in more detail below, when the cover 1 is moved to an open position, the locking element 6 separates from the retaining ring 5 along the parting line 4. Along the parting line 4, a plurality of breakable bridges 7 can be provided, connecting the retaining ring 5 to the closing element 6. The breakable bridges 7 are intended to break the first time the lid 1 is moved to the open position, to indicate that the container is no longer intact. Partition line 4 can be parallel to a free edge 16 of lid 1. More specifically, free edge 16 delimits the retaining ring 5 on the side opposite the cross wall 3. The parting line 4 does not extend at a full 360° angle around the Z-axis. The parting line 4 is interrupted in the circumferential direction, so that a joining portion 8 is defined in the side wall 2, in which the closing element 6 remains attached to the retaining ring 5. In other words, the parting line 4 has a first end 9 and a second end 10. The joining portion 8 is interposed between the first end 9 and the second end 10. In the joining portion 8, the retaining ring 5 is attached to the closing element 6. As shown in Figure 1, the joining portion 8 has an angular dimension W around the Z axis. No arrow-shaped hinges or reduced thickness zones are provided in the joining portion 8. MA / a / ZUZ 1 / un uotw In the illustrated example, the closing element 6 has a cup-shaped body and comprises a skirt 11 extending around the Z-axis. The skirt 11 is connected to the transverse wall 3, arranged at the end of the skirt 11 opposite the parting line 4. In particular, the skirt 11 is connected to the transverse wall 3 by a connection zone 12, which may be shaped, in cross-section, as a chamfered edge or a circular connection zone. The skirt 11 has, on its inner surface, removable fastening means, not shown, by means of which the closure element 6 can be removably coupled to the neck 18 of the container. The removable fastening means may comprise, for example, an internal thread intended to engage with an external thread 17, shown in Figure 3, formed on the neck 18. The skirt 11 may be provided, on an outer surface thereof, with a plurality of knurled lines 13, which extend parallel to the Z axis and are suitable for facilitating the grip of the cap 1 by the user or by the capping machine that applies the cap 1 to the container to be sealed. The knurling lines 13 can also continue into the connection area 12 and / or the retaining ring 5. In the example shown, the skirt 11 comprises a cylindrical portion 14 on which the knurling lines 13 are made. The skirt 11 further comprises a wide portion 15 having a larger diameter than the cylindrical portion 14. The wide portion 15 may be bounded by a smooth outer surface, i.e., it may be free of knurling lines. However, this condition is not required, and the knurling lines could also extend over the wide portion 15. A step 19 may be provided between the cylindrical portion 14 and the wide portion 15. The retaining ring 5 extends between the free edge 16 and the parting line 4. The retaining ring 5 may be bounded by an outer surface in the form of a cylindrical or truncated cone. In the closed position of the cover 1 shown in Figure 1, the retaining ring 5 is coaxial with the closing element 6. The retaining ring 5 is provided internally with a coupling element 20, shown in Figure 2, suitable for coupling with a circular extension 23, shown in Figure 3, projecting from an outer surface of the neck 18. The coupling element 20 is configured to rest against the circular extension 23 in order to prevent axial movement of the retaining ring 5 away from the neck 18 when the locking element 6 is withdrawn from the neck 18. The coupling element 20 may be in the form of an annular element that bends around the free edge 16 into the inside of the retaining ring 5. In an alternative embodiment not illustrated, there may be a plurality of coupling elements, shaped like tabs that protrude from the free edge 16 and are bent into the inside of the retaining ring 5. Alternatively, the coupling element 20 may be in the form of an extension, continuous or interrupted, that projects from an inner surface of the retaining ring 5 into the Z-axis to engage with the circular extension 23. As shown in Figure 1, the lid 1 has a slit line 21 that extends transversely into the side wall 2, specifically perpendicular to the Z-axis. In more detail, the slit line 21 is interposed between the parting line 4 and the free edge 16. If the lid 1 is placed in the same orientation it will have after being applied to the container, i.e., with the cross wall 3 facing upwards, the incision line 21 is positioned below the parting line 4. Therefore, the incision line 21 is located on the side of the retaining ring 5, with respect to the parting line 4. The joining portion 8 is located on the opposite side of the incision line 21 with respect to the retention ring 5. Therefore, the incision line 21 delimits the joining portion 8 towards the retention ring 5. The incision line 21 has an angular extent Al, measured about the Z-axis, greater than the angular distance (also measured about the Z-axis) between the first end 9 and the second end 10 of the parting line 4, i.e., the angular dimension W of the joining portion 8. For example, the angular extent Al of the incision line 21 can be between 60° and 200°, preferably between 75° and 180°. The angular dimension W of the joining portion 8 about the Z-axis, i.e., the angular distance between the first end 9 and the second end 10 of the parting line 4, can be between 5° and 40°, preferably between 10° and 30°. In the illustrated example, the joining portion 8 is centered with respect to the parting line 21. In other words, the midpoint of the parting line 21 and the centerline of the joining portion 8 are aligned with each other in a direction parallel to the Z-axis; that is, they lie in a common plane containing the Z-axis. However, this condition is not necessary, as even a less-centered positioning of the incision line 21 with respect to the joining portion 8 is permitted. In the illustrated example, incision line 21 has a flat, arched shape. However, other shapes are possible. The incision line 21 and the parting line 4 may be parallel to each other, although this condition is not required. For example, the incision line 21 and the parting line 4 could be slightly inclined to each other. Alternatively, the incision line 21 could comprise a plurality of segments having different inclinations, not necessarily parallel to each other. As shown in Figure 1, the incision line 21 has one end 27 and an additional end 28. End 27 extends out of the joining portion 8, beyond the first end 9 of the parting line 4. The other end 28 also extends out of the joining portion 8, but goes beyond the second end 10 of the parting line 4. The incision line 21 comprises a central portion 24 interposed between a peripheral portion 25 and another peripheral portion 26. The central portion 24 faces the joining portion 8. The peripheral portion 25 faces the parting line 4, in particular a terminal portion of the parting line 4. More precisely, the peripheral portion 25 faces the parting line 4 in an area between the first end 9 of the parting line 4 and the end 27 of the incision line 21. The other peripheral portion 26 faces the parting line 4, in particular another terminal portion of the parting line 4. More precisely, the other peripheral portion 26 faces the parting line 4 in an area between the second end 10 of the parting line 4 and the other end 28 of the incision line 21. Between the peripheral portion 25 of the incision line 21 and a portion of the parting line 4 starting from the first end 9, a connecting band 29 is defined to connect the joining portion 8 to the retaining ring 5. Similarly, between the additional peripheral portion 26 of the incision line 21 and an additional portion of the parting line 4 starting from the second end 10, an additional connecting band 30 is defined to connect the joining portion 8 to the retaining ring 5. In the illustrated example, the connecting band 29 and the additional connecting band 30 are arranged symmetrically with respect to a plane containing the Z-axis and a centerline of the joining portion 8. The incision line 21 may be in the form of a cross-section that passes through the entire thickness of the side wall 2. Although this feature is not shown in Figures 1 to 3, along the incision line 21 there may be one or more breakable elements intended to break the first time the lid 1 is opened. Alternatively, incision line 21 may be in the form of a weakening line that does not pass through the entire thickness of lateral wall 2, but in which the thickness of lateral wall 2 is reduced relative to the surrounding areas. At the first end 9 and the second end 10 of the parting line 4, and / or at the end 27 and the other end 28 of the incision line 21, there may be incision zones 38, shown in Figure 1. The incision zones 38 may have a circular geometry and, in general, have a transverse dimension greater than the width of the corresponding incision or parting line. This prevents the propagation of fractures from the incision or parting lines. In an alternative modality, the incision zones 38 may be absent. In a central portion of the joint 8, there may be a stress-reducing cut 39, which has very limited dimensions relative to the dimensions of the joint 8, so as not to negatively affect its strength. The stress-reducing cut 39 increases the deformability of the central portion of the joint 8 by reducing stress in the surrounding areas. The presence of the stress-reducing cut 39 is optional. The lid 1 is applied to the neck 18 of the container in the closed position shown in Figure 1. The lid 1 is positioned so that the locking element 20 provided inside the retaining ring 5 is below the circular widening 23 present in the neck 18. When the user wishes to open the container for the first time, the user grasps the skirt 11 of the locking element 6 and rotates the locking element 6 around the Z-axis to unscrew it from the neck 18. Initially, the locking element 6 and the retaining ring 5 rotate together around the Z-axis and simultaneously move together in a direction parallel to the Z-axis, away from the neck 18. This continues until the locking element 20 of the retaining ring 5 rests against the circular enlargement 23 provided in the neck 18. At this point, the circular enlargement 23 prevents the retaining ring 5 from moving further along the Z-axis, acting as a stop to the movement of the retaining ring 5 away from the neck 18. The locking element 6, which is unscrewed by the user, continues to move along the Z-axis away from the neck 18. This tensions the breakable bridges 7 until they break. Consequently, the locking element 6 separates from the retaining ring 5 along the parting line 4, but remains attached to the retaining ring 5 at the joining portion 8. If the user continues to unscrew the locking element 6, in order to move it along the Z-axis to remove it from the neck 18, the first connecting band 29 and the second connecting band 30 are deformed. In particular, moving the locking element 6 upwards also pulls the first connecting band 29 and the second connecting band 30 upwards. Consequently, the first connecting band 29 and the second connecting band 30 are separated from both the locking element 6 and the retaining ring 5 and remain joined together at the connecting portion 8. The first connecting band 29 and the second connecting band 30 thus adopt a trapezoidal shape as shown in Figure 2, in which the neck 18 of the vessel is not shown. In this configuration, the first connecting band 29 remains attached to the retaining ring 5 at the end 27 of the incision line 21. Similarly, the second connecting band 30 remains attached to the retaining ring 5 at the other end 28 of the incision line 21. The first connection band 29 and the second connection band 30 are joined together at the joining portion 8. In other words, the first connecting band 29 and the second connecting band are arranged in an inclined configuration with respect to the retaining ring 5 and converge at the joining portion 8. Continuing with the unscrewing of the locking element 6, it disengages from the external thread 17 in the neck 18, allowing the container to be opened. However, the retaining ring 5 remains anchored to the neck 18. The first connecting band 29, the second connecting band 30, and the joining portion 8 define a hinge arrangement 40, shown in Figure 3, around which the locking element 6 can rotate to allow the user access to the contents of the container. In particular, by moving the locking element 6 around the hinge arrangement 40 after the locking element 6 has been disengaged from the neck 18, it is possible to move the locking element 6 to a lateral position with respect to the neck 18, so that the locking element 6 is no longer coaxial with the retaining ring 5, as shown in Figure 3. The locking element 6 can then be rotated further back with respect to the position shown in Figure 3, to move it further away from the neck 18 and allow the user easier access to the contents of the container. After use, the user can return lid 1 to the closed position shown in figure 1 by following a sequence of operations in the reverse order to that described above. The first connecting band 29 and the second connecting band 30 allow for a hinge arrangement 40 that is longer than would be available if only a hinge band defined by the joining portion 8 were present. This makes it easier to disengage the locking element 6 from the neck 18 and reapply the locking element 6 to the neck 18 by rotating the locking element 6 around the hinge arrangement 40. Figures 4 to 6 and 9 show a cover 201 according to another modality. The parts of cover 201 common to cover 1, described with reference to Figures 1 to 3, shall be indicated by the reference numbers already used in Figures 1 to 3 and, for the sake of brevity, shall not be described again in detail. What has been previously described with reference to cover 1 shall be understood to also apply to cover 201, unless explicitly stated otherwise. As shown in Figures 4 to 6 and 9, the cover 201 comprises the side wall 2 extending around the Z axis, and the cross wall 3 located at one end of the side wall 2, to close off that end. The lid 201 is further provided with the parting line 4, located on the side wall 2, which defines the retaining ring 5 and the closing element 6 on the lid 201. The retaining ring 5 is intended to remain anchored to the neck of the container onto which the lid 201 is applied, by means of at least one locking element provided within it. Conversely, the closing element 6 is suitable for detachable attachment to the neck, due to the detachable fastening means provided within the skirt 11. In this way, the closing element 6 can be moved between a closed position, shown in Figures 4 and 5, and an open position, shown in Figure 9. The parting line 4 extends around the Z axis and is interrupted circumferentially to define on the side wall 2 the joining portion 8 by which the closing element 6 is joined to the retaining ring 5. Furthermore, the incision line 21 is provided on the lateral wall 2. In the illustrated example, the incision line 21 is interposed axially between the free edge 16 of the retaining ring 5 and the parting line 4. The incision line 21 comprises a peripheral part 25, an additional peripheral part 26, and a central part 24 interposed between the peripheral part 25 and the additional peripheral part 26. The incision line 21 lies entirely in a plane situated transversely, in particular perpendicularly, to the Z-axis. In other words, the peripheral part 25, the central part 24, and the additional peripheral part 26 are positioned in a common plane arranged transversely, in particular perpendicularly, to the Z-axis. Two connecting bands, i.e., a connecting band 29 and an additional connecting band 30, are defined between the parting line 4 and the incision line 21, joining the two connecting bands to the retaining ring 5 and the joining portion 8. Specifically, the connecting band 29 extends between the peripheral portion 25 of the incision line 21 and a portion of the parting line 4 starting from the first end 9 of the latter. Similarly, the additional connecting band 30 extends between the additional peripheral portion 26 of the incision line 21 and an additional portion of the parting line 4 starting from the second end 10. The connecting strip 29 and the additional connecting strip 30 can be arranged symmetrically with respect to a plane containing the Z-axis and a centerline of the joining portion 8. Figures 7 and 8 show a neck 218 onto which the cap 201 can be applied. The neck 218 extends around a longitudinal axis Zl. When the cap 201 is applied onto the neck 218 and the closing element 6 is in the closed position, the Z-axis of the side wall 2 coincides with the longitudinal axis Zl. The neck 218 is delimited by an outer surface 219, which in the illustrated example is cylindrical and coaxial with the longitudinal axis Z1. The outer surface 219 extends to a flange 220 of the neck 218. The flange 220 surrounds an opening 221 through which the container can be accessed when the locking element 6 is in the open position. Conversely, the locking element 6 closes the opening 221 when it is in the closed position. The neck 218 comprises a collar 222, suitable for preventing the retaining ring 5 from descending along the neck 218 below a predetermined level. Additionally, the collar 222 can be used to transport the container during the production, filling, and capping process. The outer surface 219 extends from the collar 222 to the rim 220. A circular enlargement 223 projects from the outer surface 219, the circular enlargement 223 being suitable for coupling with the engagement element provided within the retaining ring 5 to prevent the retaining ring 5 from separating from the neck 218. The circular widening 223 may comprise a truncated cone-shaped portion 224, the diameter of which increases in a direction from the edge 220 towards the collar 222. The circular widening 223 is delimited, on the side opposite the flange 220, by a support surface 225 against which at least one locking element of the retaining ring 5 rests. A cylindrical part of the circular enlargement 223 can be interposed between the truncated cone-shaped part 224 and the supporting surface 225. However, other geometries of the circular extension 223 are possible. The collar 218 comprises at least one removable fastening element with which the removable fastening means formed within the closure element 6 can be coupled to allow the closure element 6 to be alternatively applied to or removed from the collar 218. The at least one removable fastening element may comprise an external thread 217 formed on the outer surface 219, in particular protruding from the outer surface 219. The cap 201 is intended to be applied over the neck 218 when the locking element 6 is in the closed position. In particular, the cap 201 is applied over the neck 218 such that the at least one locking element provided inside the retaining ring 5 is below the circular enlargement 223, specifically in a position interposed between the collar 222 and the circular enlargement 223. When the user operates the lid 201 to move the locking element 6 to the open position for the first time, the locking element 6 unscrews, i.e., rotates about the longitudinal axis Z1 and simultaneously moves away from the collar 222. The retaining ring 5, attached to the locking element 6 by the breakable bridges 7, initially moves along with the locking element 6. When at least one of the locking elements provided within the retaining ring 5 presses against the bearing surface 225, the retaining ring 5 can no longer move up the collar 218. Meanwhile, the locking element 6 moves further away from the vessel body and simultaneously rotates about the longitudinal axis Z1, gradually as the user continues to unscrew the locking element 6. In this way, the breakable bridges 7 arranged along the parting line 4 are subjected to a stress that causes them to break.The connecting bands 29, 30 also deform as the locking element 6 is unscrewed. In particular, as the locking element 6 moves away from the retaining ring 5 during unscrewing, the connecting bands 29, 30 gradually become angled relative to the retaining ring 5, separating from it along the incision line 21. The locking element 6 also detaches from the connecting bands 29, 30. Any breakable material located along the incision line 21 breaks. In this way, the position shown in Figure 6 is reached, in which the neck is not shown. The position shown in Figure 6 can be defined as a disengaged position, because in the position shown in Figure 6 the removable fastening means formed within the closing element 6 have been disengaged from the thread 217 of the neck 218. At this point, the locking element 6 can be rotated relative to the retaining ring 5 to move it to the open position shown in Figure 9, in which the locking element 6 is arranged on one side of the neck 218 and the Z-axis of the locking element 6 no longer coincides with the longitudinal Z1 axis of the neck 218. The connecting bands 29, 30 are deformable, so that not only the closing element 6, but also the joining portion 8 rotates with respect to the neck 218. As shown more clearly in Figure 6, the joining portion 8 is delimited by an edge 50 which, in the closed position of the closing element 6 (and generally before the closing element 6 rotates with respect to the retaining ring 5 that is to be moved to the open position), faces the retaining ring 5. More specifically, the edge 50 is defined on the side wall 2, towards the closing element 6, by the incision line 21. When the closing element 6 moves from the uncoupled position to the open position, the joining portion 8 is flipped over with respect to the neck 218. Consequently, the edge 50, which in the uncoupled position (and also in the closed position) was oriented towards the retaining ring 5, is positioned so that it is oriented towards the edge 220 of the neck 218, i.e., upwards in the operating condition of Figure 9. To make this possible, the joining portion 8, and in particular its edge 50, slides along the truncated cone-shaped part 224 of the circular widening 223 and rotates simultaneously with respect to the joining bands 29, 30. The edge 50 reaches a height that is higher than the circular widening 223, assuming that the neck 218 is positioned so that the opening 221 faces upwards. The joining portion 8 is thus positioned at least partially above the circular widening 223, resting on the neck 218. In particular, the joining portion 8 rests on the outer surface 219 above the circular widening 223. This creates interference between the neck 218 and the connecting portion 8, particularly along and near edge 50. Interference may also occur between the connecting bands 29 and 30 and the neck 218. This allows the locking element 6 to remain stably in the open position. To return the locking element 6 to the closed position, it is necessary to overcome the interference between the connecting portion 8 and the neck 218. This does not usually happen accidentally; it only occurs if the user deliberately applies sufficient force to the locking element 6—that is, if the user intends to move the locking element 6 to the closed position. Furthermore, the interference between the joining portion 8 and the neck 218 makes it difficult for the cap 201 to rotate around the neck 218, due to the rotation of the retaining ring 5 around the neck 218. Indeed, the retaining ring 5 is connected to the joining portion 8 by the connecting bands 29 and 30. Consequently, the retaining ring 5 cannot rotate freely around the neck 218, but can only rotate if the interference between the joining portion 8 and the neck 218 is overcome. To enable the joining portion 8 to rotate when the closing element 6 moves from the disengaged position to the open position, the connecting bands 29, 30 are subjected to a twist, which affects at least part of the height H of each connecting band 29, 30. The term height H of the connecting bands 29, 30 refers to the dimension of the connecting bands 29, 30 in a direction parallel to the Z axis of the side wall 2, when the closing element 6 is in the closed position, as shown in Figure 4. In the illustrated example, in which the parting line 4 and the incision line 21 are in respective planes parallel to each other, the height H of the connecting bands 29, 30 is constant along the entire length of the connecting bands 29, 30 and is equal for the two connecting bands 29, 30. As shown in Figures 4 to 6 and 9, knurling lines 13 are provided on the locking element 6. Knurling lines 13 can extend parallel to the Z-axis. In the illustrated example, the parting line 4 intersects the knurling lines 13. In other words, the knurling lines 13 extend on both sides, that is, both above and below the parting line 4. This occurs because the separation line 4 is positioned as close as possible to the removable fastening means located within the locking element 6, i.e., to the internal thread. This allows for an increase in the height H of the connecting bands 29, 30. Accordingly, as shown in Figure 9, the connecting bands 29, 30 comprise a first portion 51 adjacent to the parting line 4, which in the example shown is provided with knurled lines 13, and a second portion 52 adjacent to the incision line 21, which in the example shown is smooth. A flared portion 53 may be provided between the first portion 51 and the second portion 52. In the illustrated example, when the joining portion 8 rotates so that the edge 50 is oriented towards the flange 220, the second part 52 of the connecting bands 29, 30 twists and passes under the first part 51. The first part 51, as well as the flared part 53, if present, on the contrary expands radially, but does not undergo substantial twisting. Due to the deformation of the connecting bands 29, 30, the joining portion 8 can rest on the neck 218 with the edge 50 facing towards the flange 220, without it being necessary to provide lines of weakening or fracture lines in the joining portion 8 and / or in the connecting bands 29, 30. In this way, the production of the cap 201 is not complicated. In the closed position, when the rim 50 faces the retaining ring 5, there is a small amount of play between the joining portion 8 and the neck 218. When the closing element 6 moves to the open position, the joining portion 8 begins to rotate and interferes with the neck 218. The interference between the joining portion 8 and the neck 218 reaches a maximum value when the joining portion 8 is positioned approximately in a plane perpendicular, or nearly perpendicular, to the neck 218, or rather to its longitudinal axis Zl. The interference between the joining portion 8 and the neck 218 is reduced when the joining portion 8 is tilted, i.e., when the rim 50 moves over the joining bands 29, 30. In the open position, the interference between the joining portion 8 and the neck 218 remains, although it is less than the maximum value. When the position where the interference reaches its maximum value is passed, the user manually rotating the locking element 6 to move it to the open position may feel a vibration. This vibration is perceived by the user's hand, as they move the locking element 6, as a discontinuity in its movement. In other words, the locking element 6 engages in place beyond the position where the interference between the joining portion 8 and the neck 218 reaches its maximum value, and the user perceives this rapid movement. In this way, the user is sure that the closing element 6 has 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 lid 201 described above ensures not only that the locking element 6 remains stably in the open position, but also that, in the open position, the locking element 6 is rotated backwards, with respect to the neck, at a relatively wide opening angle A2 as shown in Figure 9. In particular, angle A2 can be greater than or equal to 140°. This makes it very difficult for the closure element 6 to unintentionally strike the face of a user drinking directly from the bottle to which cap 201 is applied, or for the closure element 6 to obstruct the dispensing of liquid from the bottle into a container, such as a glass. Experimentation has shown that several geometric parameters of the lid 201 and / or the neck 218 favor the behavior described above with reference to figure 9. In particular, in the neck 218 it is possible to define an external or maximum diameter Dmax of the circular enlargement 223, as shown in Figure 7. It is also possible to define a diameter Ds of the outer surface 219 of the neck 218, immediately above the circular enlargement 223, i.e., in a position interposed between the circular enlargement 223 and the external thread 217. In the illustrated example, the diameter Ds immediately above the circular enlargement 223 coincides with the diameter of the outer surface 219 in a region interposed between the external thread 217 and the flange 220, but this condition is not necessary. Delta indicates the difference between the external diameter Dmax of the circular enlargement 223 and the diameter Ds of the outer surface 219 immediately above the circular enlargement 223. In the illustrated example, the external diameter Dmax of the circular enlargement 223 is 30.2 mm. The diameter Ds of the outer surface 219 immediately above the circular enlargement 223 is 28 mm. The difference Delta between Dmax and Ds is 30.2 - 28 = 2.2 mm. Half of the Delta difference expresses how far the circular extension 223 projects from the outer surface 219. As already stated, H indicates the height of the connecting bands 29, 30, i.e., the distance between the parting line 4 and the incision line 21, measured parallel to the Z axis, when the closing element 6 is in the closed position. In the illustrated example, the height H is 2.8 mm. The ratio R1 between the height H and half the difference Delta is therefore 2.8 / 1.1, that is, 2.55. It is advisable that the ratio R1 between the height H and half the difference Delta, as defined above, be greater than or equal to 1.5. It is preferable that the aforementioned ratio R1 be greater than or equal to 2. It is even more preferable that R1 be greater than or equal to 2.5. This ensures that the height H of the connecting bands 29, 30 is correctly proportional to how far the circular widening 223 projects from the outer surface 219. More specifically, if the R1 ratio is less than 1.5, it may happen that the interference created between the joining portion 8 and the neck 218 is not sufficient to stably lock the locking element 6 in an open position where the opening angle A2 is greater than or equal to 120°, preferably greater than or equal to 140°. In certain cases, a value for the R1 ratio less than 1.5, but not less than 0.8, may be acceptable. In the illustrated example, half the difference Delta between the external diameter Dmax of the circular enlargement 223 and the diameter Ds of the outer surface 219 of the neck 218, immediately above the circular enlargement 223, is Delta / 2 = 1.1 mm. It is possible to obtain a 201 lid that functions correctly even with Delta difference values ​​other than those mentioned above. In general, experimentation has shown that relatively low Delta difference values ​​(and therefore Delta / 2) are useful for obtaining behavior of the type shown in Figure 9. The joining portion 8 has an angular dimension W around the Z axis of the side wall, which has been explicitly indicated in Figure 1 and can be defined in the same way with reference to the lid 201. In the illustrated example, the angular dimension W of the joining portion 8 is 54°. In general, the angular dimension W can be greater than or equal to 20°, preferably greater than or equal to 25°. Furthermore, the angular dimension W can be less than or equal to 120°, preferably less than or equal to 90°. In one mode, the angular dimension W can be between 80° and 120°. In one configuration, the angular dimension W of the joining portion 9 can range from 30° to 110°. For example, it can be 60°. Experimentation has shown that, if the angular dimension W is greater than 120°, the connecting bands 29, 30 can break when the closing element 6 is rotated to move it to the open position. Conversely, if W is less than 20°, it may happen that the joining portion 8 fails to stably hold the closing element 6 in an open position where the opening angle A2 is greater than or equal to 120°, preferably greater than or equal to 140°. It is also possible to define a distance Y, shown in Figure 7, between the circular enlargement 223 and the at least one removable fastening element provided in the neck 219. In other words, the distance Y is measured between the upper limit of the circular enlargement 223 and the starting point of the external thread 217. The distance Y may be greater than or equal to half the distance between the parting line 4 and the incision line 21, i.e., half the height H. However, this non-parting condition 4 may be placed on a part of the side wall 2 free of knurling lines 13, for example interposed between the knurling lines 13 and the free edge 16. Consequently, in the alternative embodiment just described, the connecting bands 29, 30 are externally bounded by a smooth surface, i.e., a surface free of knurling lines. Figure 11 shows an example of this type of lid. Figure 11 shows a lid 301 in which the side wall 2 has, on an outer surface thereof, a plurality of knurled lines 13. In the example in Figure 11, the parting line 4 is provided on a portion of the side wall 2 without knurling lines 13, i.e., on a smooth portion of the side wall 2. This occurs because the knurling lines 13 have respective lower ends (i.e., closer to the free edge 16) that are separated from the parting line 4. Therefore, the parting line 4 is provided on a non-knurled portion of the side wall 2. The breakable bridges 7 arranged along the parting line 4 are visible in the example in figure 11. Some breakable elements 70 arranged along the incision line 21 are also visible. The breakable elements 70 may be similar to the breakable bridges 7. In the example shown, the breakable elements 70 are offset with respect to the breakable bridges 7, in a direction parallel to the Z-axis of the cover 301. In other words, a plane containing the Z-axis and passing through a breakable bridge 7 does not cross any breakable element 70. In other words, the breakable elements 70 are arranged in positions angularly displaced around the Z axis with respect to the breakable bridges 7. Each breakable bridge 7 and each breakable element 70 can have a width, measured in a circumferential direction, respectively, along the parting line 4 and along the incision line 21, equal to 0.4 mm. The lid 301 shown in Figure 11 exhibits similar behavior during opening and closing to that of lid 201 shown in Figures 4 to 6 and 9. More specifically, when the closing element 6 of lid 301 moves from the closed to the open position, the connecting bands 29 and 30 deform with a torsional movement that can affect a portion of their height, similar to what is shown in Figures 9 and 10 for lid 201. In the example in Figure 11, the first portion 51 adjacent to the parting line 4 and the second portion 52 adjacent to the incision line 21 are both smooth, i.e., without knurling lines. The connecting bands 29, 30 shown in Figure 11 can be deformed such that the first portion 51 expands radially without undergoing substantial torsion. The second portion 52, on the other hand, can be rotated to pass under the first portion 51, to interpose itself between the first portion 51 and the outer surface 219 of the neck 218. In this way, the edge 50 can pass beyond the circular widening 223 and be positioned at a height above it, i.e., closer to the edge 220 than the circular widening 223. This allows the joining portion 8 to rotate with respect to the connecting bands 29, 30, passing over, i.e., at a greater height, the circular widening 223 and resting on the outer surface 219. As shown in Figure 11, the parting line 4 is placed at a distance DI from the free edge 16 of the retaining ring 5. The DI distance is less than or equal to 6.5 mm. Preferably, the DI distance is less than or equal to 5 mm. The DI distance is greater than or equal to 2 mm. Preferably, the DI distance is greater than or equal to 3 mm. In a preferred mode, the DI distance is therefore between 3 and 5 mm. Partition line 4 may have an angular extent, around the Z-axis, greater than or equal to 250°. The angular extent of partition line 4 may be less than or equal to 330°. In one mode, the angular extension of the separation line 4 can be between 250° and 280°. Incision line 21 is placed at a distance D2 from the free edge 16 of the retention ring 5. The D2 distance can be greater than or equal to 1 mm. The distance D2 can be less than or equal to 5 mm. More specifically, the distance D2 can be less than or equal to 4 mm. In one mode, the D2 distance can be between 1 and 3 mm. In one mode, the D2 distance can be equal to 3.9 mm. The incision line 21 may have an angular extension around the Z axis greater than or equal to 120°. This angular extension may be less than or equal to 250°. In one modality, the incision line 21 may have an angular extension greater than or equal to 130°. The angular extension of the incision line 21 may be less than or equal to 200°. The angular extension of the incision line 21 can be, for example, equal to 160°. In one modality, the angular extension of the incision line 21 can be between 180° and 250°. The connection strips 29, 30 can have a height H greater than or equal to 1 mm and less than or equal to 5.5 mm. Height H is measured parallel to the Z axis, in the closed position of lid 1. MA / a / ZUZ 1 / un uotw More specifically, the connection strips 29, 30 can have a height H greater than or equal to 1.2 mm and less than or equal to 4 mm. In one version, the height H varies from 1.2 mm to 3.5 mm. The height H can be equal to 2 mm. In one embodiment, the 301 cover can have a height Hl, measured in a direction parallel to the Z axis, between 10 and 21 mm. As shown in Figure 12, each connecting strip 29, 30 can have a radial thickness S, i.e., a thickness measured in a radial direction with respect to the Z-axis, greater than or equal to 0.35 mm. This thickness can be less than or equal to 1.8 mm. In one embodiment, the radial thickness S of each connecting strip 29, 30 can be greater than or equal to 0.5 mm. This thickness can be less than or equal to 1.2 mm. The radial thickness S of the connecting strips 29, 30 can be constant in a direction parallel to the Z-axis. Alternatively, the radial thickness S of the connecting strips 29, 30 can be variable in a direction parallel to the Z-axis. More specifically, the radial thickness S of the connecting strips 29, 30 can vary along a direction parallel to the Z-axis, such that it remains within the ranges indicated above. In one mode, the relatively large radial thicknesses S of the connection bands 29, 30 correspond to a relatively small height H, and vice versa. For example, if the radial thickness S is in the upper half of the 0.35-1.8 mm range, i.e., in the 1.1-1.8 mm range, the height H may be in the lower half of the 1-5.5 mm range, i.e., in the 1-3.2 mm range. The reverse also applies; that is, if the radial thickness S varies in the range of 0.35–1.1 mm, the height H can vary in the range of 3.2–5.5 mm. However, it is also possible to combine relatively large radial thicknesses S of the connecting strips 29, 30 with a relatively large height H. Below are some examples of the dimensions that lids of the type shown in Figure 11 can have. ML / a / ZUZ 1 / un uotw Cap / neck type S [mm] H [mm] H / S 29 / 25 mm 0.7 1.2 1.71 29 / 25 mm 0.7 2.3 3.29 PCO 1881 0.75 3.5 4.67 30 / 25 mm 0.65 2.7 4.15 30 / 25 mm 0.45 2.45 5.44 3 threads 38 mm 0.7 3.1 4.43 29 / 25 mm 0.85 1.2 1.4 30 / 25 mm 0.55 2.8 5.1 It has been experimentally found that these lids remain stably open with an opening angle A2 of at least 120°. The ratio between the height H of the connecting bands (i.e., the distance between the parting line 4 and the incision line 21) and the radial thickness S of the connecting bands may be greater than or equal to 1.4. The aforementioned 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 can be less than or equal to 6.5. These values ​​ensure that the connecting bands 29, 30 have optimal torsional rigidity to deform as described above and generate sufficient interference between the neck and the joining portion 8 (and possibly between the neck and the connecting bands 29, 30) to reliably and securely hold the locking element 6 in the open position. The numerical values ​​defined above with reference to cover 301 shown in figure 11 are also applicable to cover 201 shown in figures 4 to 6, 9 and 10. The 201 or 301 lid is also particularly easy to make. Indeed, the lid 201 or 301 can be obtained starting from a concave body comprising the side wall 2 and the cross wall 3. The concave body is produced by molding a polymeric material, for example compression molding or injection molding. Once the concave body has been formed, the parting line 4 and the incision line 21 are made on the lateral wall 2. The parting line 4 and the scoring line 21 can be created by cutting operations, for example, performed in a cutting unit located downstream of a mold in which the concave body has been formed. Such cutting operations can be performed using respective blades, for example, circular or linear, which interact with the side wall 2 from either the outside or the inside. In particular, the concave body can be rotated around the Z-axis of the side wall 2, while the blades are held in position, so that successive areas of the side wall 2 interact with the blades one after the other. It is also possible to hold the concave body in position and rotate the blades to perform the cut. The blades that allow obtaining the parting line 4 and the incision line 21 can be configured to interact with the side wall 2 in respective parallel planes, for example perpendicular to the Z axis, if, as in the examples shown so far, the parting line 4 and the incision line 21 must be in respective parallel planes. The blades may have an interrupted edge if, along the parting line 4, the breakable bridges 7 must remain defined and / or if, along the incision line 21, the respective breakable elements must remain defined. Incision line 21 can be made using a blade having a flat cutting edge, so that incision line 21 lies in a plane for the entire length of incision line 21. It is also possible that the blades do not cut through the entire thickness of side wall 2, but only partially cut through the thickness of side wall 2, to leave, along the incision line 21 and / or along the parting line 4, a thin membrane intended to break the first time the lid is opened. Parting line 4 and incision line 21 can be performed simultaneously or during two separate steps. Therefore, the 201 or 301 cap is particularly easy to manufacture, as the concave body can be formed in an ordinary mold. There is no need for undercut or thin parts other than those normally provided for a cap of the known type. An additional operation, namely making incision line 21, can be done very easily while obtaining parting line 4. There are possible incision line geometries different from those shown so far. For example, Figure 13 shows a lid 401 according to an alternative embodiment, which differs from that shown in Figure 11 because it comprises an incision line 421 that is not in a single plane, but is defined by two curved segments 421a and 421b that lie in respective planes and converge on a common line. That is, the curved segments 421a and 421b converge at a point P which, in the example in Figure 13, is positioned higher than the remaining extension of the curved segments 421a and 421b. The example in Figure 15 shows, on the other hand, a lid 601 whose incision line 621 is defined by two curved segments 621a, 621b that converge at a point P1 positioned lower than the remaining extension of the curved segments 621a, 621b. In the example in Figure 14, on the other hand, a cap 501 is provided having a notched line 521 that is not flat, but has a curved tendency on the side wall of the cap, with the concavity downwards, i.e., towards the free edge 16 of the retaining ring 5. Finally, Figure 16 shows a cover 701 whose incision line 721 has a curved shape with the concavity upwards, i.e., towards the closing element 6. The lids described above are made of plastic, for example polypropylene (PP) or polyethylene (PE). If PE is used, its density can vary from low to high density. More specifically, high-density polyethylene (HDPE) can be used. The high-density polyethylene (HDPE) used to produce the lids described above may have the following properties: a variable density between 950 and 968 kg / m3; variable melting index from 0.3 to 20 g, under the following measurement conditions: 10 minutes, 190°C, 2.16 kg; large, or narrow, or unimodal or multimodal distribution of molecular weight. If PP is used, the material can be in the form of a homopolymer, heterophasic copolymer, or statistical copolymer. The melting index of PP can vary from 2 to 20 g, under the following measurement conditions: 10 minutes, 230°C, 2.16 kg.

Claims

1. A lid for a container, comprising a side wall (2) extending around an axis (Z) and a cross wall (3) disposed at one end of the side wall (2), a parting line (4) being provided in the side wall (2) to define: - a retaining ring (5) intended to remain anchored to a neck (218) of the container, and - a closing element (6) that can be detachably attached to the neck (218), for opening or closing the container;where the parting line (4) extends around the axis (Z) and is interrupted circumferentially to leave a joining portion (8) between the retaining ring (5) and the closing element (6), the cap further having a slit line (21) extending transversely to the axis (Z) between the parting line (4) and a free edge (16) of the retaining ring (5), such that two connecting bands (29, 30) are defined between the parting line (4) and the slit line (21), the connecting bands (29, 30) joining the retaining ring (5) to the joining portion (8), the connecting bands (29, 30) having a radial thickness (S) measured in a radial direction, the connecting bands (29, 30) further having a height (H) measured parallel to the axis (Z), and where the ratio between the height (H) and the radial thickness (S) of the connecting bands (29, 30) is greater than or equal to to 1.4, said ratio being less than or equal to 6.5.; 2. The cover according to claim 1, further characterized in that the height (H) of the connecting strips (29, 30) is greater than or equal to 1 mm and less than or equal to 5.5 mm, preferably said height (H) is greater than or equal to 1.2 mm and less than or equal to 4 mm.

3. The cover according to claim 1 or 2, further characterized in that the radial thickness (S) of the connecting strips (29, 30) is greater than or equal to 0.35 mm and less than or equal to 1.8 mm, said radial thickness (S) preferably being greater than or equal to 0.5 mm and less than or equal to 1.2 mm.

4. The lid according to claim 1, further characterized in that the radial thickness (S) is greater than or equal to 1.1 mm and less than or equal to 1.8 mm, the height (H) being greater than or equal to 1 mm and less than or equal to 3.2 mm.

5. The lid according to claim 1, further characterized in that the radial thickness (S) is greater than or equal to 0.35 mm and less than or equal to 1.1 mm, the height (H) being greater than or equal to 3.2 mm and less than or equal to 5.5 mm.

6. The lid in accordance with any of the preceding claims, further characterized in that the parting line (4) and the incision line (21) are cutting lines.

7. The lid according to any of the preceding claims, further characterized in that along the parting line (4) a plurality of breakable bridges (7) is provided, along the incision line (21) a plurality of breakable elements (70) is provided, the breakable bridges (7) and the breakable elements (70) being intended to break the first time the lid is opened.

8. The cover according to claim 7, further characterized in that the breakable elements (70) are arranged in positions angularly displaced around the (Z) axis with respect to the breakable bridges (7).

9. The lid in accordance with any of the preceding claims, further characterized in that the incision line (21) is located in a plane arranged transversely, for example perpendicularly, to said axis (Z), when the closing element (6) is in a closed position.

10. A lid for a container, comprising a side wall (2) extending about an axis (Z) and a cross wall (3) disposed at one end of the side wall (2), a parting line (4) being provided in the side wall (2) to define: - a retaining ring (5) intended to remain anchored to a neck (218) of the container, and - a closing element (6) that can be detachably attached to the neck (218), for opening or closing the container; where the parting line (4) extends around the axis (Z) and is interrupted circumferentially to leave a joining portion (8) between the retaining ring (5) and the closing element (6), the cap further having a slit line (21) extending transversely to the axis (Z) between the parting line (4) and a free edge (16) of the retaining ring (5), so that two connecting bands (29, 30) are defined between the parting line (4) and the slit line (21),The connecting bands (29, 30) joining the retaining ring (5) to the joining portion (8), the incision line (4), and the parting line (21) are cutting lines, wherein along the parting line (4) a plurality of breakable bridges (7) is provided, along the incision line (21) a plurality of breakable elements (70) is provided, the breakable bridges (7) and the breakable elements (70) being intended to break the first time the lid is opened, wherein the incision line (21) comprises a peripheral part (25), an additional peripheral part (26), and a central part (24) interposed between the peripheral part (25) and the additional peripheral part (26), and wherein the incision line (21) lies in a plane arranged perpendicular to said axis (Z).

11. The cover in accordance with any of the preceding claims, further characterized in that the joining portion (8) has an angular dimension (W), measured around the axis (Z), greater than or equal to 30° and less than or equal to 110°.

12. The cover in accordance with any of the preceding claims, further characterized in that the incision line (21) has an angular extension (Al), measured around the axis (Z), greater than or equal to 120° and less than or equal to 250°, said angular extension (Al) preferably being greater than or equal to 130° and less than or equal to 200°.

13. The cover according to any of the preceding claims, further characterized in that the parting line (4) is placed at a distance (DI) from the free edge (16) of the retaining ring (5) that is greater than or equal to 2 mm and less than or equal to 6.5 mm, the distance (DI) of the parting line (4) from the free edge (16) being preferably greater than or equal to 3 mm and less than or equal to 5 mm.

14. The cover in accordance with any of the preceding claims, further characterized in that the incision line (21) is arranged at a distance (D2) from the free edge (16) of the retaining ring (5) that is greater than or equal to 1 mm and less than or equal to 5 mm, the distance between the incision line (21) and the free edge (16) being preferably less than or equal to 4 mm.

15. A combination of a lid for a container and a neck (218) of a container, wherein the neck (218) is delimited by an outer surface (219) from which a circular enlargement (223) projects, the outer surface (219) extending to a flange (220) of the neck (218), the flange (220) facing upwards in an operating condition, and wherein the lid comprises a side wall (2) extending about an axis (Z), a parting line (4) being provided in the side wall (2) to define: - a retaining ring (5) intended to engage with the circular enlargement (223) to remain anchored to the neck (218), - and a locking element (6) that can be detachably attached to the neck (218) to be movable between a closed position and an open position,where the parting line (4) extends around the axis (Z) and is interrupted circumferentially to leave a joining portion (8) between the retaining ring (5) and the closing element (6), the cap further having a slit line (21) extending transversely to the axis (Z) between the parting line (4) and a free edge (16) of the retaining ring (5), such that two connecting bands (29, 30) are defined between the parting line (4) and the slit line (21), the connecting bands (29, 30) joining the retaining ring (5) to the joining portion (8), the connecting bands (29, 30) being deformable by a torsional movement affecting at least a portion of the height (H) of each connecting band (29, 30), such that the joining portion (8) rotates with respect to the connecting bands (29, 30) when the closing element (6) is moved from the closed position to open position, and so that an edge (50) of the joining portion (8) that,In the closed position, it faces the retaining ring (5), and is positioned at least partially above the circular enlargement (223), thus creating an interference between the joining portion (8) and the neck (218) to keep the closing element (6) in the open position.

16. The combination according to claim 15, further characterized in that, in the open position, there is also interference between the connecting bands (29, 30) and the neck (218).

17. The combination according to claim 15 or 16, further characterized in that each connecting band (29, 30) comprises a first portion (51) adjacent to the parting line (4) and a second portion (52) adjacent to the incision line (21), the first portion (51) being configured to expand radially so that the second portion (52) twists under the first portion (51) when the closing element (6) is moved from the closed position to the open position.

18. A combination of a lid for a container and a neck (218) of a container, wherein the neck (218) is delimited by an outer surface (219) from which a circular enlargement (223) projects, the outer surface (219) extending to a flange (220) of the neck (218), and wherein the lid comprises a side wall (2) extending about an axis (Z), a parting line (4) being provided in the side wall (2) to define: - a retaining ring (5) intended to engage with the circular enlargement (223) to remain anchored to the neck (218), - and a locking element (6) that can be detachably attached to the neck (218) to be movable between a closed position and an open position, wherein the parting line (4) extends about the axis (Z) and is circumferentially interrupted to leave a joining portion (8) between the retaining ring (5) and the locking element (6),the lid further having a slit line (21) extending transversely to the (Z) axis between the parting line (4) and a free edge (16) of the retaining ring (5), such that between the parting line (4) and the slit line (21) two connecting bands (29, 30) are defined, the connecting bands (29, 30) joining the retaining ring (5) to the joining portion (8), wherein each connecting band (29, 30) comprises a first portion (51) adjacent to the parting line (4) and a second portion (52) adjacent to the slit line (21), the first portion (51) being configured to expand radially so that the second portion (52) rotates and passes under the first portion (51), thereby interposing itself between the first portion (51) and the neck (218) when the closing element (6) moves from the closed position to the open position.

19. The combination according to any of claims 15 to 18, further characterized in that the distance (H) between the parting line (4) and the incision line (21) is equal to or greater than 0.8 times half the difference (Delta) between an outer diameter (Dmax) of the circular enlargement (223) and a diameter (Ds) of the outer surface (19) of the neck (218) immediately above the circular enlargement (223), said distance (H) being preferably equal to, or greater than, 1.5 times half the difference (Delta).

20. A combination of a lid for a container and a neck (218) of a container, wherein the neck (218) is delimited by an outer surface (219) from which a circular enlargement (223) projects, the outer surface (219) extending to a flange (220) of the neck (218), and wherein the lid comprises a side wall (2) extending about an axis (Z), a parting line (4) being provided in the side wall (2) to define: - a retaining ring (5) intended to engage with the circular enlargement (223) to remain anchored to the neck (218), - and a locking element (6) that can be detachably attached to the neck (218) to be movable between a closed position and an open position, wherein the parting line (4) extends about the axis (Z) and is circumferentially interrupted to leave a joining portion (8) between the retaining ring (5) and the locking element (6),further having in the lid a slit line (21) extending transversely to the axis (Z) between the parting line (4) and a free edge (16) of the retaining ring (5), such that two connecting bands (29, 30) are defined between the parting line (4) and the slit line (21), the connecting bands (29, 30) joining the retaining ring (5) to the joining portion (8), and wherein a distance (H) between the parting line (4) and the slit line (21) is equal to or greater than 0.8 times half the difference (Delta) between an external diameter (Dmax) of the circular enlargement (223) and a diameter (Ds) of the external surface (19) of the neck (218) immediately above the circular enlargement (223), said distance (H) being preferably equal to or greater than 1.5 times half of said difference (Delta).

21. The combination according to any of claims 15 to 20, further characterized in that the joining portion (8) has an angular dimension (W) about said axis (Z) greater than or equal to 20°, preferably greater than or equal to 25°.

22. The combination according to any of claims 15 to 21, further characterized in that the joining portion (8) has an angular dimension (W) about said axis (Z) less than or equal to 120°, preferably less than or equal to 90°.

23. The combination according to any of claims 15 to 22, further characterized in that, in the closed position of the closing element (6), the incision line (21) is located in a plane arranged transversely to the (Z) axis, said edge (50) being defined by the incision line (21) in a central part (24) thereof.

24. The combination in accordance with any of claims 15 to 23, further characterized in that the joining portion (8) is joined to the connecting bands (29, 30) without interposing fracture lines or lines of weakness.

25. The combination according to any of claims 15 to 24, further characterized in that the side wall (2) is provided externally with a plurality of knurling lines (13), the parting line (4) intersecting the knurling lines (13).

26. The combination according to any of claims 15 to 25, further characterized in that, in the open position, the locking element (6) is rotated backwards, with respect to the neck (218), at an opening angle (A2) greater than or equal to 120°.

27. The combination according to any of claims 15 to 26, further characterized in that the locking element (6) is configured to generate a vibration that can be perceived by a user when the locking element (6) is moved from the closed position to the open position, the vibration being generated in a condition of maximum interference between the joining portion (8) and the circular enlargement (223).

28. The combination in accordance with any of claims 15 to 27, further characterized in that the lid is a lid according to any of claims 1 to 14.

29. A method comprising the following steps: - producing a lid for a container, the lid comprising a side wall (2) extending about an axis (Z) and a transverse wall (3) disposed at one end of the side wall (2), - making a parting line (4) by cutting in the side wall (2) to define a retaining ring (5) intended to remain anchored to a neck (218) of the container, and a closing element (6) that can removably engage the neck (218) to open or close the container, wherein the parting line (4) extends about the axis (Z) and is interrupted circumferentially to leave a joining portion (8) between the retaining ring (5) and the closing element (6), - making an incision line (21) by cutting, the incision line (21) extending transversely to the axis (Z), such that between the parting line (4) and the incision line (21) two connecting bands (29, 30) are defined,The connecting bands (29, 30) join the retaining ring (5) to the joining portion (8).

30. The method according to claim 29, further characterized in that the parting line (4) and the incision line (21) are made using blades having an interrupted cutting edge to define a plurality of breakable bridges (7) along the parting line (4) and to define a plurality of breakable elements (70) along the incision line (21).

31. The method according to claim 29 or 30, further characterized in that the incision line (21) is made using a blade having a flat cutting edge. SUMMARY OF THE INVENTION A lid for a container comprises a side wall (2) extending about an axis (Z) and a cross wall (3) disposed at one end of the side wall (2); a parting line (4) is provided in the side wall (2) to define: - a retaining ring (5) intended to remain anchored to a neck (18; 218) of the container, and - a closing element (6) that can be detachably coupled to the neck (18; 218) to open or close the container; the parting line (4) extends about the axis (Z) and is circumferentially interrupted to leave a joining portion (8) between the retaining ring (5) and the closing element (6); the lid (1;10 201) further has a slit line (21) extending transversely to the (Z) axis between the parting line (4) and a free edge (16) of the retaining ring (5), such that between the parting line (4) and the slit line (21) two connecting bands (29, 30) are defined, the connecting bands (29, 30) joining the retaining ring (5) to the joining portion (8); the connecting bands (29, 30) have a radial thickness measured in a radial direction and a height (H) measured parallel to the (Z) axis; 15 the ratio between the height (H) and the radial thickness of the connecting bands (29, 30) is greater than or equal to 1.4 and less than or equal to 6.5.;

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