Patent Description:
In particular, the invention relates to a cap provided with a retaining ring, joinable to a container neck, the cap also being provided with a closing element which, after opening, remains connected to the retaining ring.

The cap is particularly, but not exclusively, suitable for bottles intended to contain liquid substances.

There are prior art bottle caps comprising a cup-shaped body having a lateral wall extending around an axis, the cup-shaped body being provided with an inner thread suitable for engaging with an outer thread of a neck of the bottle. The prior art caps are also provided with a security ring connected to the cup-shaped body by means of a tear line provided with a plurality of breakable elements, for example breakable bridges. When the cap is opened for the first time, the cup-shaped body separates from the security ring along the tear line following breaking of the breakable bridges. The security ring remains joined to the neck of the bottle, whilst the cup-shaped body can be unscrewed by the user, who in this way separates the cup-shaped body from the bottle to access the contents of the bottle. Subsequently, the cup-shaped body can be screwed onto the neck again to reclose the bottle.

Sometimes, after the bottle has been emptied, the user throws the cup-shaped body on the ground, intentionally or accidentally, whilst the bottle, together with the security ring joined to it, is correctly thrown in a waste bin. Obviously, this is unwanted behaviour.

In order to overcome this disadvantage, caps have been proposed which are provided with a separating line made in a lateral wall of the cap to define a retaining ring, configured to remain anchored to a neck of the container, and a closing element, which can removably engage with the neck, so as to open or close the container. The retaining ring is provided with a retaining portion, which extends as far as a free edge of the retaining ring and is configured to internally engage with a locking ring of the neck. These caps additionally comprise an incision line also provided on the lateral wall to define, together with the separating line, at least one connecting band positioned for connecting the closing element and the retaining portion to each other.

Along the separating line, or along the incision line, the breakable bridges may be present, which are intended to be broken the first time the cap is opened.

The closing element can be rotated between an open condition, in which a user can access the contents of the bottle, and a closed condition, in which the closing element prevents access to the bottle.

The connecting band keeps the closing element joined to the retaining ring and therefore to the bottle, preventing the possibility of the closing element being thrown on the ground independently from the bottle.

Moreover, the connecting band allows the closing element to be moved away from the retaining portion of the retaining ring, which remains anchored to a locking ring of the neck of the container during opening of the container. Indeed, it is possible to make use of the movement capacity of the connecting band itself, in passing from the closed condition to the open condition, and vice versa.

The cap may be obtained from a concave body which comprises the lateral wall and a transversal wall placed at one end of the lateral wall, and it may be made for example by moulding a polymeric material, for example compression moulding or injection moulding.

After the concave body has been formed, the separating line and the incision line are made on the lateral wall using cutting tools, which may for example be blades positioned perpendicularly to the axis Z, if the separating line and the incision line lie, for example in respective parallel planes, which are for example perpendicular to the axis Z.

If we now consider the lateral wall, it comprises a first portion starting from the free edge which is without thread and a second portion, starting from the transversal wall which is provided with the thread.

Since they are made by means of cutting operations, the separating line and the incision line may be positioned in the lateral wall only in the first portion which is without thread but not in the second portion in which the thread is present.

Since the connecting band is made by the separating line, together with the incision line, the axial height of the connecting band is defined by the positioning of the separating line and of the incision line relative to each other in the first portion of the lateral wall.

To ensure that the connecting band is sturdy and that it does not break along with the breakable bridges when the cap is opened for the first time, the connecting band must have a minimum axial height. However, this is not always possible if the caps have a small height.

Indeed, for relatively short caps, the thread may leave free a portion of cap, which extends as far as the free edge, which is so small as to mean that the connecting band, which is made in it, has a height unsuitable for guaranteeing sturdiness and deformability of the self-same connecting band.

The sturdiness of the connecting band guarantees that the latter does not break, whilst the deformability of the connecting band guarantees correct locking of the closing element, when the cap is in the open condition.

Indeed, in prior art caps, the retaining ring, in the open condition, when a user inclines the bottle to pour its contents, can easily rotate and also cause the closing element connected to it fall downwards due to gravity. If that happens, the closing element may be positioned facing and below the dispensing opening. Therefore, the user is obliged to manually lock the cap before inclining the bottle, in order to avoid undesired splashes or deviations of the content to be poured and have the guarantee that the closing element does not disturb the dispensing.

If the connecting band is deformable, it can be subjected to bending and can operate in conjunction with the neck to keep the cap stably locked in the same position in the open condition.

<FIG> show caps, which have a small height, in which the possibility of making a separating line <NUM> and an incision line <NUM> intended to define at least one connecting band is considered.

Specifically, the caps <NUM> below which are illustrated in <FIG> show two connecting bands <NUM> and <NUM> but it should be noticed that the considerations provided below may also apply to various variants of caps, even provided with only one connecting band.

In the caps with small height, shown in <FIG>, the incision line <NUM> is positioned between the separating line <NUM> and a free edge of the cap and the separating line <NUM>, which defines the closing element and the retaining ring, is circumferentially interrupted in order to keep the closing element and the retaining ring joined together by means of a joining portion.

The separating line <NUM> is positioned at a distance D1 from the free edge of the retaining ring. The height of the retaining ring along an axis parallel to the axis Z is therefore equal to D1.

H1 indicates a height of the connecting bands and D2 indicates a height of a retaining portion, along an axis parallel to the axis Z when the closing element is in the closed condition. The incision line <NUM>, <NUM>' is therefore positioned at a distance D2 from the free edge of the retaining ring.

H2 indicates a height of the cap <NUM>, measured between the transversal wall and the free edge.

In <FIG>, in which the projecting tab is present, D3 indicates the distance between the central stretch of the incision line and the free edge.

Therefore, it should be noticed that there is a transition from the first portion to the second portion positioned at a distance equal to T1 from the free edge <NUM>, and that the separating line <NUM> can be positioned in the lateral wall of the cap in the first portion.

If the height D1 of the retaining ring is small due to the thread in the second portion, the height H1 of the connecting bands may be small, as shown in <FIG> and <FIG>.

If, in addition, the tab <NUM>' which projects relative to the connecting bands is present, as illustrated in <FIG>, although keeping the distance D3 relative to the free edge to a minimum, the height H1 of the connecting bands is even smaller, since the tab <NUM>' itself must also be made within the height D1 of the retaining ring.

Consequently, considering a cap <NUM> with small height which is currently widespread on the market and assuming that at least one connecting band is made in it so as to keep the closing element connected to the retaining ring in the cap open condition, that connecting band may have a height insufficient to guarantee that, during opening of the container, or during its subsequent use, the connecting band will not break.

Moreover, the thickness being inadequate, the deformability of the connecting band, or of the two connecting bands previously shown, could be insufficient to guarantee that the closing element will remain stably locked in the same position in the closed condition.

Document <CIT> shows a closing cap which includes a first and a second closing portion. The first closing portion includes an upper wall portion and a first and a second breakable connection, wherein the first breakable connection extends around the closing circumference and the second breakable connection is at a distance from the first breakable connection, at least one portion of the second breakable connection being located further from the upper wall portion than a portion of the first breakable connection. The second breakable connection defines an area suitable for forming a tab.

An aim of the invention is to improve the prior art caps, in particular the caps comprising a retaining ring intended to remain joined to a neck of the container and a closing element which can removably engage with the neck to allow a user to open or alternatively close the container.

A further aim is to provide a cap for a container, provided with a closing element which remains connected to the retaining ring, which additionally may remain stably locked in a position after opening, even when the height of the cap is small.

A different aim of the invention is to provide a cap, provided with at least one connecting band, positioned between a closing element of the cap and a retaining portion of the retaining ring and intended to remain anchored to a locking ring of the neck, which is sturdy and deformable in the cap open condition, even when the height of the cap is small.

According to one aspect of the invention, a cap for a container is provided according to claim <NUM> and the claims dependent on it.

The invention can be better understood and implemented with reference to the accompanying drawings, which illustrate several example, non-limiting embodiments of it, in which:.

With reference to the appended <FIG>, the numeral <NUM> denotes a closing cap for a container, not illustrated, in particular a bottle intended to contain a liquid substance such as a beverage.

It should be noticed that, in this description, the same reference numbers will be assigned to identical components.

The cap <NUM> is made of polymeric material. Any polymeric material suitable for moulding may be used to obtain the cap <NUM>.

The cap <NUM> is shown in <FIG> in a condition in which the cap <NUM> is found when it leaves a cap production line and can be applied to a neck, not illustrated, of the container, in combination with it.

The cap <NUM> comprises a lateral wall <NUM> which extends around an axis Z, and a transversal wall <NUM> positioned at one end of the lateral wall <NUM>, so as to close that end. The transversal wall <NUM> extends transversally, in particular perpendicularly, to the axis Z.

The axis Z is a central axis, of symmetry for the cap <NUM>.

The transversal wall <NUM> may be flat, even though other shapes are theoretically possible. In the example illustrated, the transversal wall <NUM> has a substantially circular shape in plan view.

The lateral wall <NUM> and the transversal wall <NUM> define a cup-shaped body, suitable for receiving an end portion of the neck of the container, so that the cap <NUM> can close the self-same container.

In particular, the lateral wall <NUM> is connected to the transversal wall <NUM> by a connecting zone <NUM>, which may be shaped, in cross section, like a bevelled edge or a circular connector.

The cap <NUM> comprises a separating line <NUM>, shown at least in <FIG>, which is provided on the lateral wall <NUM> to define a retaining ring <NUM>, which is configured to remain anchored to the neck of the container.

The separating line <NUM>, on the lateral wall <NUM>, defines not just the retaining ring <NUM>, but also a closing element <NUM> removably engageable with the neck, so as to open or close the container. The closing element <NUM> is engageable for closing a dispensing opening, not illustrated, of the container.

The retaining ring <NUM> comprises a retaining portion <NUM> which is configured to internally engage with a locking ring of the neck, not illustrated, in such a way as to remain anchored to the self-same neck.

The locking ring is an annular protuberance, which projects from an outer surface of the neck in a plane placed transversally to the axis Z.

The retaining portion <NUM> extends as far as a free edge <NUM> of the retaining ring <NUM>, which delimits the retaining ring <NUM> on the opposite side to the transversal wall <NUM>.

In other words, the retaining portion <NUM> is a lower portion of the retaining ring <NUM>, and therefore of the cap <NUM>, when the cap is joined to the container and is configured to keep the retaining ring <NUM> anchored to the neck of the container.

The lateral wall <NUM> may be provided, on an outer surface thereof, with a plurality of knurling lines <NUM>, extending parallel to the axis Z and suitable for facilitating gripping of the cap <NUM> by the user or by the capping machine which applies the cap <NUM> on the container to be closed.

The knurling lines <NUM> may be positioned in the closing element <NUM>, but may also continue in the connecting zone <NUM> and/or in the retaining ring <NUM>.

In the example shown in <FIG>, it should be noticed that the lateral wall <NUM> comprises a cylindrical portion which extends as far as the connecting zone <NUM>, on which the knurling lines <NUM> are made, a widened portion with diameter greater than the cylindrical portion, which extends as far as the free edge <NUM> of the retaining ring <NUM> and a connecting zone positioned between the cylindrical portion and the widened portion. The knurling lines <NUM> are provided on the connecting zone but not in the widened portion, which is externally delimited by a smooth outer surface, that is to say, it can be free of knurling lines <NUM>. However, that is not necessary, since the knurling lines <NUM> could also extend on the widened portion.

<FIG> shows that in the connecting zone the knurling lines <NUM> are interrupted and there is a mark <NUM> present, which is optically recognisable, having a rectangular shape and a smooth outer surface, so that optical inspection systems for the cap <NUM>, which are present in cap <NUM> production lines, can optically tell the difference between it and the knurling lines <NUM>. An incision line <NUM>, shown in <FIG>, <FIG>, is provided on the lateral wall <NUM> and defines, together with the separating line <NUM>, at least one connecting band for connecting the closing element <NUM> and the retaining portion <NUM> to each other.

The separating line <NUM> and the incision line <NUM> can be made as cutting lines by means of a cutting operation on a concave body obtained by moulding.

The cutting lines may pass through the entire thickness of the lateral wall, or not pass through if the thickness of the lateral wall is to be only partially cut.

Preferably, the separating line <NUM> and the incision line <NUM> are made by means of through cuts passing through an entire thickness of the lateral wall.

Optionally, along the separating line <NUM> there may be a plurality of breakable bridges <NUM>, whilst along the incision line <NUM>, there may be a plurality of breakable elements <NUM>, which are shown in <FIG>, <FIG>, those breakable bridges <NUM> and breakable elements <NUM> being intended to break the first time the cap <NUM> is opened. The breakable elements <NUM> may be positioned in angularly offset positions around the axis Z relative to the breakable bridges <NUM>.

Preferably, the breakable bridges <NUM> are provided along the separating line <NUM> but not on the incision line <NUM>.

As indicated in more detail below, concerning the position of the incision line <NUM> relative to the separating line <NUM> different variants of the cap <NUM> may be identified as regards, for example, the position of the connecting band or the number of connecting bands present.

As already indicated, the separating line <NUM> is positioned at a distance D1 from the free edge <NUM> of the retaining ring <NUM>. The height of the retaining ring <NUM> along an axis parallel to the axis Z is therefore equal to D1.

H1 indicates a height of the connecting band and D2 indicates a height of the retaining portion <NUM>, along an axis parallel to the axis Z when the closing element <NUM> is in the closed condition.

H2 indicates a height of the cap <NUM>, measured between the transversal wall <NUM> and the free edge <NUM>.

As shown at least in <FIG>, <FIG>, <FIG> and <FIG>, the cap <NUM> additionally comprises a coupling structure <NUM>, or thread, positioned inside the lateral wall <NUM> for removably coupling the closing element <NUM> to the neck of the container.

<FIG> shows how the thread <NUM> has three starts, that is to say, it comprises three distinct helical curved threads <NUM>, each of which extends continuously for an angle α which is equal to <NUM>° and begins every <NUM>°.

<FIG> also shows how there are three distinct optically recognisable marks <NUM> present, which are angularly spaced by an angle β which is also equal to <NUM>° and they are in turn spaced relative to a starting position of each thread <NUM>.

Alternatively, the angular spacing of each mark <NUM> relative to each thread <NUM> may be equal to <NUM>°, or equal to any other value necessary in the cap <NUM> production lines in order to allow a check of quality or assembly of the cap on the container.

This applies not just for the cap <NUM> of <FIG>, but also for the caps which will be described below and which also have respective optically recognisable marks.

The lateral wall <NUM> has a first portion <NUM> without the thread <NUM> which has a first height T1 measured along an axis parallel to the axis Z starting from the free edge <NUM>.

The separating line <NUM> and the incision line <NUM> are positioned on the first portion <NUM> since it is necessary that the cutting operations, which may be necessary in order to make them, are carried out in the portion without the thread <NUM>.

The lateral wall <NUM> also has a second portion <NUM> provided with the thread <NUM> which has a second height T2 measured along an axis parallel to the axis Z starting from the transversal wall <NUM>.

The sum of the first height T1 and of the second height T2 is equal to the height H2 of the cap <NUM> and consequently, at a distance from the free edge <NUM> equal to the first height T1, a transition from the first portion <NUM> to the second portion <NUM> is present, that is to say, the thread <NUM> begins.

At the first portion <NUM>, on the inside of the lateral wall <NUM> there is a cylindrically shaped inner surface, whilst at the second portion <NUM> the inner surface is in the shape of the thread <NUM>.

A connecting surface <NUM> may be present in the first portion <NUM> to connect the inner surface in the shape of the thread of the second portion <NUM> and the cylindrical inner surface of the first portion <NUM>. As shown in <FIG> and <FIG>, the connecting surface <NUM> may have a conical shape or alternatively, as shown in <FIG> and <FIG>, it may have a planar shape.

According to this invention, the ratio between the second height T2 and the first height T1 is less than or equal to <NUM> so that the connecting band can be made with suitable dimensions. The term "suitable" dimensions means that the dimensions of the connecting band are such that they keep the closing element <NUM> stably connected to the retaining ring <NUM> when the closing element <NUM> is in an open condition.

In other words, if we consider the second height T2 as the dividend and the first height T1 as the divisor, the ratio between them, which is less than or equal to <NUM>, guarantees that the connecting band can have the characteristics necessary for keeping the closing element <NUM> and the retaining ring <NUM> connected during the passage from the closed condition to the open condition and when the cap <NUM> is in the open condition.

Thanks to the connecting band, which stably connects the closing element <NUM> to the retaining portion <NUM> when the cap is in the open condition, the possibility of the closing element <NUM> being thrown on the ground separately from the container is prevented. This increases the probability that the closing element <NUM>, together with the container, is correctly disposed of together with waste of the same type as it, in particular with waste made of plastic material.

Thanks to the fact that the ratio between the second portion <NUM>, provided with the thread <NUM> and the first portion <NUM>, without the thread <NUM> is less than or equal to <NUM>, it is guaranteed that part of the height H2 of the cap <NUM>, established proportionally relative to the height H2, always remains without the thread <NUM> so that it is possible to make in said part the separating line <NUM> and the incision line <NUM>, which together define the height H1 of the connecting band.

Even if the cap <NUM> has a small overall height H2, it is guaranteed that the height H1 of the connecting band, defined by the separating line <NUM> and by the incision line <NUM> which are present in the first portion <NUM>, may be kept to a size sufficient to ensure that the connecting band is sturdy and can deform, in the cap open condition, when it is subjected to stress by a user. This allows the closing element <NUM> to be stably locked on the neck of the container when the cap is in the open condition and prevents any rotating movement of the closing element, either towards the dispensing opening or around the neck of the bottle. Therefore, the closing element cannot fall due to gravity, as illustrated below.

Even when the user wants to close the container again, the presence of a sturdy connecting band allows the passage from the open condition to the closed condition without the connecting band breaking.

According to one variant of the invention, the ratio between the second height T2 and the first height T1 is less than or equal to <NUM>, preferably it is less than or equal to <NUM>.

The ratio between the second height T2 and the first height T1 is greater than or equal to <NUM>.

As a result, the ratio between the second height T2 and the first height T1 is greater than or equal to <NUM> and less than or equal to <NUM>; preferably greater than or equal to <NUM> and less than or equal to <NUM>; even more preferably greater than or equal to <NUM> and less than or equal to <NUM>.

The Applicant has noticed that said size ratios are particularly advantageous for caps <NUM> which have a height H2 greater than or equal to <NUM> and less than or equal to <NUM>, preferably for caps <NUM> which have a height greater than or equal to <NUM> and less than or equal to <NUM>, even more preferably for caps <NUM> which have a height greater than or equal to <NUM> and less than or equal to <NUM>.

For example, the cap <NUM> of <FIG>, has height H2 equal to <NUM>. According to this invention, the first height T1 is equal to <NUM>, the second height T2 is equal to <NUM> and the ratio between the second height T2 and the first height T1 is equal to <NUM>.

Therefore, it should be noticed that, although the height H2 of the cap is small, it is particularly advantageous to have the first portion <NUM> with increased height, so as to guarantee that a significant portion of the cap <NUM> is available for being able to make the separating line <NUM> and the incision line <NUM>.

However, it should be noticed that the ratio between the second portion <NUM> and the first portion <NUM>, according to the invention, may be applied to any type of cap. Indeed, even in caps with height H2 greater than <NUM> it could still be advantageous to have a first portion <NUM> with increased height if one wants the closing element <NUM> to be locked on the neck resting on a coupling structure of the neck, beyond the locking ring, in order to render even more stable the combination of the cap and the neck on which the cap is applied.

If the first portion <NUM> has increased height in accordance with this invention, irrespective of the height H2 of the cap <NUM>, it therefore follows that the second portion <NUM>, in which the thread <NUM> is present, is small. As a result of this, when the cap <NUM> engages with the neck of the container, the thread <NUM> engages with the corresponding thread of the neck of the container later than in a cap <NUM> which has the same height H2 but is not made according to this invention.

The cap <NUM> also comprises a sealing element <NUM> which extends from an inner surface of the transversal wall <NUM> internally relative to the lateral wall <NUM> and, in use, is configured to be positioned inside the dispensing opening of the neck in order to form a seal with an inner wall of the neck.

That sealing element <NUM> is made as a cylindrical wall which protrudes from the transversal wall <NUM> as far as a sealing end <NUM>, which has increased thickness and protrudes radially outward towards the lateral wall <NUM> so as to create the seal with the inner wall of the neck, when the sealing element <NUM> is inserted in the dispensing opening of the neck.

The sealing element <NUM> is coaxial relative to the lateral wall <NUM> and has a height H3 measured along an axis parallel to the axis Z starting from the transversal wall <NUM>.

The height H3 of the sealing element <NUM> is less than or equal to the first height T1.

In other words, even the height H3 of the sealing element <NUM> is small so as to ensure that the sealing element <NUM> engages with the neck of the container only after the thread <NUM> of the cap <NUM> has engaged with the corresponding thread of the neck, during closing of the cap <NUM>.

The small dimensions of the sealing element <NUM> guarantee that the cap <NUM> can be screwed onto the neck of the container in the usual way, despite the thread <NUM> according to this invention engaging with the neck later than the thread of a cap which is not made according to this invention.

It should be noticed that reference is made to "small" dimensions compared with corresponding dimensions of a cap <NUM> of the same height, already known but not made according to this invention.

If we now consider the transition at the height T1 (from the free edge <NUM>) between the first portion <NUM> and the second portion <NUM>, it can be seen how the separating line <NUM>, or the incision line <NUM>, is advantageously positioned at a distance (not illustrated) less than or equal to <NUM> from said transition and therefore at a height less than or equal to <NUM> from the height T1.

Preferably, the separating line <NUM>, or the incision line <NUM>, may be positioned at a distance preferably less than or equal to <NUM> from said transition, preferably equal to <NUM>, from said transition.

Thanks to this distance from the transition, the separating line <NUM>, or the incision line <NUM>, may be made in a zone of the lateral wall <NUM> which is, radially, the stiffest of the cap <NUM>. Consequently, the cutting operation necessary to make the separating line <NUM>, or the incision line <NUM>, is extremely efficient, since the cutting tools are capable of making optimum contact with the lateral wall <NUM>, therefore maximising a penetration in the lateral wall <NUM>, which allows the achievement of high cutting precision and minimum wear on the cutting tools themselves.

As already indicated, the retaining ring <NUM> is configured to internally engage with the locking ring in such a way as to remain anchored to the neck.

For that purpose, as shown in <FIG>, the retaining ring <NUM> is internally provided with an engaging element <NUM>, suitable for engaging with the locking ring. The engaging element <NUM> is configured to abut against the locking ring in order to prevent axial movements of the retaining ring <NUM>, away from the neck, when the closing element is moved away from the neck.

In detail, it is the retaining portion <NUM> of the retaining ring <NUM> which is provided with the engaging element <NUM>, in such a way that it is kept anchored to the locking ring even when the closing element <NUM> is in the open condition and is locked at a distance from the neck and from the dispensing opening.

The engaging element <NUM> is shaped like an annular element which is bent around the free edge <NUM> inwards towards the inside of the retaining portion <NUM>. In detail, the annular element may be continuous or interrupted. Indeed, there may be a plurality of bent elements, shown in <FIG>, shaped like tabs, which project from the free edge <NUM> and are bent inwards towards the inside of the retaining portion <NUM> to form the engaging element. Alternatively, according to an embodiment not illustrated, the engaging element <NUM> may be shaped like a continuous or interrupted protuberance, which from an inner surface of the retaining portion <NUM> projects towards the axis Z to engage with the locking ring.

If we now consider the cap <NUM> of <FIG> and position the separating line <NUM> and the incision line <NUM> in it, as shown in <FIG>, <FIG>, we can see how there may be a plurality of connecting bands present, for example two, that is to say, a first connecting band <NUM> and a second connecting band <NUM> for connecting the closing element <NUM> and the retaining portion <NUM> to each other, the connecting bands being defined by the separating line <NUM> together with the incision line <NUM>.

In detail, the first connecting band <NUM> and the second connecting band <NUM> are defined between the separating line <NUM> and the incision line <NUM>.

Advantageously, since the separating line <NUM>, or the incision line <NUM> are near the height T1, it is possible to obtain the first connecting band <NUM> and the second connecting band <NUM> with height sufficient for them to be sturdy and not break.

The incision line <NUM> comprises a first lateral stretch <NUM> and a second lateral stretch <NUM>, which at least partly define the first connecting band <NUM> and the second connecting band <NUM>. The first connecting band <NUM> is defined between the first lateral stretch <NUM> and a first part of the separating line <NUM>, which extends from a first end <NUM> of the separating line <NUM>.

The second connecting band <NUM> is defined between the second lateral stretch <NUM> and a second part of the separating line <NUM>, which extends from a second end <NUM> of the latter.

The separating line <NUM> extends around the axis Z and is circumferentially interrupted so as to leave the retaining ring <NUM> and the closing element <NUM> joined by a joining portion <NUM>. In detail, the separating line <NUM> extends between the first end <NUM> and the second end <NUM>.

The incision line <NUM> extends between the separating line <NUM> and the free edge <NUM> of the retaining ring <NUM>.

Therefore, the retaining ring <NUM> extends between the separating line <NUM> and the free edge <NUM> and may be delimited by a cylindrical or frustoconical outer surface.

Preferably, the separating line <NUM> is parallel to the free edge <NUM>.

The first connecting band <NUM> and the second connecting band <NUM> are therefore positioned in the retaining ring <NUM> and extend from the joining portion <NUM> to the retaining portion <NUM>.

The first connecting band <NUM> and the second connecting band <NUM> are positioned circumferentially on opposite sides of the joining portion <NUM>.

It should be noticed that the incision line <NUM> has an angular extent, measured around the axis Z, which is greater than the angular distance (also measured around the axis Z) between the first end <NUM> and the second end <NUM> of the separating line <NUM>, that is to say, the angular extent of the joining portion <NUM>.

In addition, the joining portion <NUM> extends circumferentially in the angular extent of the incision line <NUM>.

The first lateral stretch <NUM> and the second lateral stretch <NUM> of the incision line <NUM> are both perpendicular to the axis Z and are aligned. However, in an embodiment not illustrated, the two lateral stretches <NUM> and <NUM> could be slightly angled relative to each other and have different inclinations, not necessarily parallel to each other.

The first lateral stretch <NUM> and the second lateral stretch <NUM> preferably extend, in a first plane (not illustrated) parallel to a separating plane (not illustrated) containing the separating line <NUM>, the first plane being transversal to the axis Z, in particular perpendicular to the axis Z.

When the cap <NUM> is in the open condition, the first lateral stretch <NUM> and the second lateral stretch <NUM> respectively define a first free lower edge, not illustrated, and a second free lower edge, not illustrated, of the connecting bands <NUM>, <NUM>.

In addition, the first lateral stretch <NUM> and the second lateral stretch <NUM> also define a first free upper edge, not illustrated, and a second free upper edge, not illustrated, of the retaining portion <NUM>.

The first lateral stretch <NUM> and the second lateral stretch <NUM> are positioned at the distance D2 from the free edge <NUM> of the retaining ring <NUM>, along an axis parallel to the axis Z, which corresponds to the height of the retaining portion <NUM>.

The incision line comprises a central stretch <NUM> which is interposed between the first lateral stretch <NUM> and the second lateral stretch <NUM> of the incision line <NUM> and defines an end edge which in the closed condition is facing the retaining portion <NUM> and is configured to be directed, when the cap is in the open condition, towards the neck, or towards the dispensing opening, of the container.

It should be noticed that, as shown in <FIG>, and <FIG>, the central stretch <NUM> as well as the two lateral stretches <NUM> and <NUM> are positioned in a single plane which is positioned transversally, in particular perpendicularly to the axis Z.

When the closing element <NUM> passes from the closed condition to the open condition, the joining portion <NUM> deforms and is overturned relative to the neck, so that the end edge can rest on the neck itself.

A centre line of the joining portion <NUM> and a centre line of the incision line <NUM> may be positioned angularly near each other.

Preferably, the centre line of the separating line <NUM> and the centre line of the incision line <NUM> coincide with each other, as shown in <FIG>, and <NUM>, so that the first connecting band <NUM> and the second connecting band <NUM> are positioned symmetrically relative to a plane containing the axis Z and a centre line of the joining portion <NUM>, and the first connecting band <NUM> and the second connecting band <NUM> are of equal length.

According to one embodiment not illustrated, the centre line of the incision line <NUM> may not coincide with the centre line of the joining portion <NUM>, provided that it is angularly near it as previously said, and in that case the first connecting band <NUM> may have a different length to the second connecting band <NUM>, since the first lateral stretch <NUM> and the second lateral stretch <NUM> may have a different angular extent.

As illustrated in <FIG>, the retaining ring <NUM> comprises a tab <NUM> so that when the closing element <NUM> is in an open condition and the connecting bands <NUM>, <NUM> keep the closing element <NUM> connected to the retaining ring <NUM>, the tab <NUM> can rest on the neck.

The central stretch <NUM> defines the end edge of the tab <NUM>, when the cap <NUM> is in the open condition.

Two cutting lines <NUM> are provided on the lateral wall <NUM> to define the respective lateral edges of the tab <NUM> and they are formed by cutting lines which pass through an entire thickness of the lateral wall <NUM>.

The central stretch <NUM> of the incision line <NUM> is positioned between the cutting lines <NUM> and is also interposed between the first lateral stretch <NUM> and the second lateral stretch <NUM> of the incision line.

If, as illustrated in <FIG>, the central stretch <NUM> as well as the two lateral stretches <NUM> and <NUM> are aligned with each other and in the single plane positioned transversally, in particular perpendicularly, to the axis Z, the end edge of the tab <NUM> is aligned with the first free lower edge, and with the second free lower edge, of the connecting bands <NUM>, <NUM>.

If we consider a height of the tab <NUM>, this is determined by the height of the cutting lines <NUM>.

Otherwise, as illustrated in <FIG>, the cap <NUM> may comprise a tab <NUM>', which differs from the tab <NUM> illustrated in <FIG> due to the fact that it has an incision line <NUM>' which comprises a central stretch <NUM>' which extends in a second plane, parallel to the separating plane and interposed between the first plane and the free edge <NUM> of the retaining ring <NUM>, to define an end edge of the tab <NUM>' which projects relative to the connecting bands <NUM>, <NUM>.

Indeed, whilst the first lateral stretch <NUM> and the second lateral stretch <NUM> are similar to those of <FIG>, the incision line <NUM>' has the central stretch <NUM>' which is nearer to the free edge <NUM> in order to define the tab <NUM>' projecting relative to the connecting bands <NUM>, <NUM>.

D3 indicates the distance between the central stretch <NUM>' and the free edge <NUM>.

In this case too, the height of the tab <NUM>' is determined by the height of the cutting lines <NUM>, which extend from the central stretch <NUM>' until they intercept the lateral stretches <NUM>, <NUM>.

In one embodiment not illustrated, the cutting lines <NUM> may continue in the joining portion <NUM> and optionally also in the closing element <NUM> to give the tab <NUM> greater flexibility relative to a virtual hinge line, placed on the opposite side to the end edge between the opposite ends of the cutting lines <NUM>.

Whilst the tab <NUM> of <FIG> is made in the height H1 of the connecting bands <NUM>, <NUM>, the tab <NUM>' of <FIG> is made exclusively as an external part, projecting relative to the first connecting band <NUM> and the second connecting band <NUM>.

<FIG> shows a cap which differs from the cap of <FIG> due to the fact that the joining portion <NUM> is externally provided with a projection <NUM>, which projects from the joining portion <NUM> and is positioned between the separating line <NUM> and the incision line <NUM>, so that, when the closing element <NUM> is in the open position and the connecting bands <NUM>, <NUM> keep the closing element <NUM> connected to the retaining ring <NUM>, the end edge defined by the central stretch <NUM> of the incision line is directed, in the open position, towards the dispensing opening of the container and the projection <NUM> is resting on the neck.

The projection <NUM> operates in conjunction with the overturning of the joining portion <NUM> and can stabilise and lock the closing element <NUM> on the neck, preventing the connecting bands <NUM> and <NUM> from rotating in the opposite direction.

Now considering the shape of the cap <NUM> and the positioning of the separating line <NUM>, it should be noticed that the closing element <NUM> is defined by the cylindrical portion whilst the retaining ring <NUM> is defined by the widened portion since the separating line <NUM> is provided on the widened portion, near to the first height T1 at which the first portion <NUM> without the thread <NUM> begins.

However, other cap <NUM> configurations could be possible, with respect to the position of the separating line <NUM>, the extent of the knurling lines <NUM> and the outer shape of the cap <NUM>. For example, the separating line <NUM> may be positioned on the cylindrical portion, if the transition from the first portion <NUM> to the second portion <NUM> occurs at the self-same cylindrical portion.

According to one variant not illustrated, the separating line <NUM> and the incision line <NUM> have angular extent greater than <NUM>° and the centre line of the separating line <NUM> and the centre line of the incision line <NUM> are positioned angularly opposite each other. Preferably, the separating line <NUM> and the incision line <NUM> have equal angular extent.

According to this variant, the separating line <NUM> and the incision line <NUM> only overlap each other between the first part of the separating line <NUM> and the first lateral stretch <NUM> of the incision line <NUM> and between the second part of the separating line <NUM> and the second lateral stretch <NUM> to define respectively the first connecting band <NUM> and the second connecting band <NUM>.

According to a further variant not illustrated, the separating line <NUM> is positioned between an incision line and the free edge <NUM>. In this case, the retaining ring <NUM> coincides with the retaining portion <NUM> and the connecting bands <NUM>, <NUM> are made in the closing element <NUM>.

The joining portion <NUM>, defined between the first end <NUM> and the second end <NUM> of the separating line <NUM>, is joined to the retaining portion <NUM>.

The first connecting band <NUM> and the second connecting band <NUM>, when the cap passes from the closed condition to the open condition, thereby adopt a trapezium-shaped configuration, not illustrated, but the smaller base of the trapezium is directed towards the free edge <NUM>, whilst the larger base of the trapezium, defined by the incision line, is directed towards the transversal wall <NUM>.

In other words, the central stretch of the incision line is facing the closing element <NUM>, and in detail, is facing an end edge of the closing element <NUM>. Therefore, it should be noticed that, advantageously, in all of the embodiments of the cap <NUM> according to this invention, illustrated in the accompanying figures or only described, the presence of a ratio between the second height T2 of the second portion <NUM> and the first height T1 of the first portion <NUM>, allows the first portion <NUM> to have a height sufficient to make in it the separating line <NUM>, or the incision line <NUM>, which are positioned in such a way as to guarantee at least one sturdy and deformable connecting band.

According to <FIG> what is proposed is a variant 1a of a cap <NUM> according to this invention which differs from the cap <NUM> shown in <FIG> since it has a coupling structure 2a which is a variant of the coupling structure <NUM>, having a single thread 201a, which is angularly interrupted in order to leave equally spaced vents <NUM> at which the thread 2a is absent.

The cap 1a of <FIG> has the height H2 equal to <NUM>. According to this invention, the first height T1 is equal to <NUM>, the second height T2 is equal to <NUM> and the ratio between the second height T2 and the first height T1 is equal to <NUM>.

The thread 201a extends from a start <NUM> a' to an end <NUM> a", as shown in <FIG>, which are separated by an angular distance equal to <NUM>°.

The cap 1a of <FIG> has a single start and is particularly suitable for use with carbonated beverages.

Moreover, as illustrated in <FIG>, it can be seen how an optically recognisable mark 311a is present which differs from the mark <NUM> of <FIG> since it is also shaped like a knurling line <NUM> but it has a different height to all of the others which are present in the lateral wall <NUM>.

As shown in <FIG>, there is a single mark 311a and it is positioned angularly spaced relative to the start 201a' and to the end 201a" of the thread 201a.

According to <FIG> what is proposed is a further embodiment 1b of a cap <NUM> according to this invention which differs from the cap <NUM> shown in <FIG> since it comprises an optically recognisable mark 311b which differs from the mark <NUM> of <FIG> and also from the mark 311a of <FIG>.

The cap 1b of <FIG> has the height H2 equal to <NUM>. According to this invention, the first height T1 is equal to <NUM>, the second height T2 is equal to <NUM> and the ratio between the second height T2 and the first height T1 is equal to <NUM>.

The mark 311b is also shaped like a knurling line <NUM> but it has a different height to all of the others which are present in the lateral wall <NUM>, which is also different to the height of the mark 311a of <FIG>.

The cap 1b has a coupling structure <NUM> with three starts, similar to that of <FIG> and, that is to say, it has the three helical curved threads <NUM>, each of which extends continuously for an angle α which is equal to <NUM>° and begins every <NUM>°.

<FIG> also shows how there are three distinct optically recognisable marks 311b present, which are angularly spaced by the angle β which is also equal to <NUM>° and they are in turn spaced relative to a starting position of each thread <NUM>.

The cap 1b of <FIG> may also optionally have two threads.

Moreover, as illustrated in <FIG>, it can be seen how the cap 1b has an engaging element 313b which differs from the engaging element <NUM> of <FIG> since it is shaped like a plurality of flaps, positioned circumferentially at a predetermined distance from the free edge <NUM>, which are associated with each other in pairs, opposite each other, and project from the retaining portion <NUM> towards each other. The flaps are bent inwards towards the inside of the retaining portion <NUM> to form the engaging element 313b.

According to <FIG> what is proposed is a further embodiment 1c of a cap <NUM> according to this invention which differs from the cap <NUM> shown in <FIG> since it comprises a coupling structure 2c which is another variant of the coupling structure <NUM> and has three starts, that is to say, it has three helical curved threads 201c, each of which begins at each angle α which is equal to <NUM>° but extends for an angle γ equal to <NUM>°.

The cap 1c of <FIG> has the height H2 equal to <NUM>. According to this invention, the first height T1 is equal to <NUM>, the second height T2 is equal to <NUM> and the ratio between the second height T2 and the first height T1 is equal to <NUM>.

The three threads 201c are angularly interrupted in order to leave nine equally spaced vents 202c at <NUM>° from each other, at which the thread 2c is absent.

It should be noticed that the caps 1a, 1b, 1c of <FIG> have the first portion <NUM> of the lateral wall <NUM>, without thread <NUM>, and the second portion <NUM>, provided with thread <NUM>, for which it remains a valid fact that the ratio between the second height T2 and the first height T1 is less than or equal to <NUM>, preferably less than or equal to <NUM>, even more preferably less than or equal to <NUM>.

In this way, although not having been illustrated, it can be guaranteed that the height H1 of the at least one connecting band (or of the connecting bands <NUM>, <NUM>, if there are two) obtained in the first portion <NUM>, is of sufficient height to guarantee that the connecting band itself is sturdy and deformable.

According to this invention, if the connecting band is defined between the separating line <NUM> and the incision line <NUM>, it may advantageously have a height H1 at least greater than or equal to <NUM>, preferably greater than <NUM>, even more preferably greater than <NUM>.

Other embodiments of caps according to this invention are possible, as regards the dimensions of the first height T1, of the second height T2 and the ratio between the second height T2 and the first height T1, as indicated below.

For example, in a first other embodiment of the cap <NUM>, not illustrated, the second height T2 is equal to <NUM>, the first height T1 is equal to <NUM> and the ratio between the second height T2 and the first height T1 is equal to <NUM>; in a second other embodiment of the cap <NUM>, not illustrated, the second height T2 is equal to <NUM>, the first height T1 is equal to <NUM> and the ratio between the second height T2 and the first height T1 is equal to <NUM>; in a third other embodiment of the cap <NUM>, not illustrated, the second height T2 is equal to <NUM> and the first height T1 is equal to <NUM> and the ratio between the second height T2 and the first height T1 is equal to <NUM>; in a fourth other embodiment of the cap <NUM>, not illustrated, the second height T2 is equal to <NUM> and the first height T1 is equal to <NUM> and the ratio between the second height T2 and the first height T1 is equal to <NUM>.

In use, the cap <NUM> is applied on the neck of the container in the closed condition. The cap <NUM> is positioned in such a way that the engaging element <NUM> provided inside the retaining ring <NUM>, in particular on the retaining portion <NUM> is below the locking ring which is present on the neck.

When the user wishes to open the container for the first time, the user grips the closing element <NUM> and rotates the closing element <NUM> around the axis Z, in order to unscrew the closing element <NUM> from the neck. Initially, the closing element <NUM> and the retaining ring <NUM> are rotated together around the axis Z, and they simultaneously move together in a direction parallel to the axis Z, away from the neck, the coupling structure <NUM> of the cap <NUM> engaging with the corresponding coupling structure of the neck of the container.

During the initial rotation of the closing element <NUM> and of the retaining element <NUM> away from the neck, the sealing element <NUM> continues to remain in contact with the inner wall of the neck so that it continues to make a seal.

This occurs until the engaging element <NUM> of the retaining portion <NUM> abuts against the locking ring provided on the neck. At this point, the locking ring prevents the retaining portion <NUM> from rising further along the axis Z, acting as a stop for the movement of the retaining portion <NUM>, and therefore of the retaining ring <NUM>, away from the neck.

The closing element <NUM>, which is unscrewed by the user, continues to move along the axis Z away from the neck. The breakable bridges <NUM> are thereby tensioned, until causing them to break. The closing element <NUM> consequently separates from the retaining ring <NUM> along the separating line <NUM>, but remains joined to the retaining ring <NUM> at the joining portion <NUM>.

In particular with reference to <FIG>, <FIG>, if the user continues to unscrew the closing element <NUM>, so as to move the closing element <NUM> along the axis Z to remove it from the neck, the first connecting band <NUM> and the second connecting band <NUM> deform since they extend between the retaining portion <NUM>, locked by the locking ring <NUM>, and the joining portion <NUM>, fixed and joined to the closing element <NUM>, which moved away from the locking ring and was lifted upwards.

If the tab <NUM>, or <NUM>', is present, it also moves away from the locking ring whilst the first connecting band <NUM> and the second connecting band <NUM> are pulled upwards.

If present, the breakable elements <NUM> of the joining portion are thereby tensioned, until causing them to break.

Subsequently, the first connecting band <NUM> and the second connecting band <NUM> are spaced apart from both the closing element <NUM> and the retaining portion <NUM> and remain joined to each other in the joining portion <NUM>.

The first connecting band <NUM> and the second connecting band <NUM> thus adopt a trapezium-shaped configuration, not illustrated. If the tab <NUM>, or <NUM>', is present it may be positioned in the smaller base of the trapezium.

If the first connecting band <NUM> has the same length as the second connecting band <NUM>, the trapezium which may be described by them is of the Isosceles type. If, in contrast, the connecting bands <NUM>, <NUM> have different lengths, they will adopt a scalene trapezium type shape. As regards the position of the tab <NUM>, or <NUM>' in the joining portion <NUM>, it will be possible for the tab <NUM>, or <NUM>' to be positioned centrally or laterally.

The first connecting band <NUM> remains joined to the retaining portion <NUM> at an outer end of the first lateral stretch <NUM> of the incision line <NUM>. Similarly, the second connecting band <NUM> remains joined to the retaining portion <NUM> at an outer end of the second lateral stretch <NUM> of the incision line <NUM>, the outer end of the first lateral stretch <NUM> and the outer end of the second lateral stretch <NUM> externally delimiting the incision line <NUM> circumferentially. If the first connecting band <NUM> and the second connecting band <NUM> are positioned in a configuration angled relative to the retaining portion <NUM> and they converge in the joining portion <NUM>, the tab <NUM>, or <NUM>' extends along an axis which is parallel to the axis Z.

Continuing to unscrew the closing element <NUM>, the latter disengages from the coupling structure, or thread, made on the neck, so that the container can be opened. In contrast, the retaining portion <NUM> of the retaining ring <NUM> remains anchored to the neck.

The joining portion <NUM> defines a hinge band, which keeps the closing element <NUM> connected to the neck and around which the closing element <NUM> can rotate moving away from the neck and which at the same time deforms to allow rotation of the closing element <NUM> relative to the neck.

In other words, after having disengaged from the neck, the closing element <NUM> can be rotated around the joining portion <NUM>.

In addition, the joining portion <NUM>, the first connecting band <NUM>, the second connecting band <NUM> and optionally the tab <NUM>, or <NUM>', are joined to each other and define a hinge arrangement which has a capacity for movement, in an axial direction, noticeably greater than the capacity for movement which would be allowed by the joining portion <NUM> alone.

The hinge arrangement is a part of the retaining ring <NUM> which is interposed between the retaining portion <NUM> of the retaining ring <NUM> and the closing element <NUM>.

For a cap as shown in <FIG>, in the open condition, the connecting bands <NUM> and <NUM> can deform. Indeed, if we consider a first strip, directed towards the closing element <NUM> and a second strip directed towards the end edge, the first strip can expand radially, without being subjected to a substantial twisting whilst the second strip can in contrast twist in order to pass below the first portion, interposing itself between the first strip and the outer surface of the neck. In this way, when the end edge of the first stretch <NUM> towards the dispensing opening of the container, the second strip of the connecting bands <NUM> and <NUM> is twisted and is below the first portion. This allows the closing element <NUM> to be kept stably fixed in the same position in the open condition.

Thanks to the sturdiness of the connecting bands <NUM>, <NUM> and to their deformability, the connecting bands <NUM>, <NUM> can twist without breaking.

For a cap as shown in <FIG> in which the projection <NUM> is present, in the open condition, the connecting bands <NUM> and <NUM> may bend but they are not subjected to a complete twist.

Indeed, the projection <NUM> comes to rest on the neck and allows the closing element <NUM> to be kept stably fixed in the open condition.

If, in contrast, a tab <NUM>, or <NUM>' is present, as shown in <FIG>, by moving the closing element <NUM> around the joining portion <NUM>, after the closing element <NUM> and if necessary the tab <NUM>, or <NUM>', have disengaged from the neck, it is possible to move the closing element <NUM> into a position at the side of and at a distance from the neck, until the tab <NUM>, or <NUM>' is locked resting on the neck.

In the open condition, the end edge of the tab <NUM>, or <NUM>', intercepts the neck of the container and can rest near the locking ring of the neck since the locking ring prevents the tab <NUM>, or <NUM>' from rotating any further.

For example, the tab <NUM>, or <NUM>', can rest in the outer zone of the neck located between the locking ring and a lower thread <NUM> of the thread <NUM>, or on the thread <NUM> itself, depending on the shape of the retaining ring <NUM>, and/or of the locking ring of the neck and/or the height H of the tab <NUM>, or <NUM>'.

The end edge of the tab <NUM>, <NUM>' becomes directed towards the dispensing opening of the container and the tab <NUM> prevents the closing element <NUM> from being able to accidentally rotate towards the neck and around it.

In the case of the tab <NUM> of <FIG>, the end edge of the tab <NUM> remains aligned with the first free lower edge, and with the second free lower edge, of the connecting bands <NUM>, <NUM>.

In the case of the tab <NUM>' of <FIG>, the end edge of the tab <NUM>' projects relative to the connecting bands <NUM>, <NUM>.

When a user wants to close the container again, in order to be able to completely disengage the tab <NUM>, or <NUM>', or the projection <NUM>, from the neck of the container, the closing element <NUM> must be moved further away. However, the tab <NUM>, or <NUM>', or the projection <NUM> may also optionally bend so as to disengage its end edge from the neck.

Again, it should be noticed that it is essential that the connecting bands <NUM>, <NUM> have a suitable height, since the user must be able to pull and bend the connecting bands <NUM>, <NUM>, in order to open and close the container, even many times at least until he or she wants to dispose of the container as waste.

The caps <NUM>, 1a, 1b and 1c previously described are made of plastic material, for example polypropylene (PP) or polyethylene (PE).

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

The high density polyethylene (HDPE) used to make the caps previously described may have the following properties:.

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

The melt index of PP may vary from <NUM> to <NUM>, in the following measuring conditions: <NUM> minutes, <NUM>, <NUM>.

This invention is advantageously applicable to caps <NUM>, 1a, 1b, 1c which are suitable for use, for example, on necks in the following list, each neck being associated with a respective code which identifies the name of the neck, the diameter of the outer surface of the neck, and the diameter of the dispensing opening of the neck, in accordance with the nomenclature of CETIE (www. org) or ISBT (www.

For each code, if the neck is also a European standard, the reference number is also provided.

Claim 1:
A closing cap (<NUM>; 1a; 1b; 1c) for a container, comprising a lateral wall (<NUM>) extending around an axis (Z) and a transversal wall (<NUM>) positioned at one end of the lateral wall (<NUM>), a separating line (<NUM>) being provided on the lateral wall (<NUM>) to define a retaining ring (<NUM>), which comprises a retaining portion (<NUM>) which extends as far as a free edge (<NUM>) of the retaining ring (<NUM>) and is configured to internally engage with a locking ring of a neck of the container in such a way as to remain anchored to the neck, and a closing element (<NUM>) removably engageable with the neck, so as to open or close the container; the cap additionally comprising an incision line (<NUM>; <NUM>'), which is also provided on the lateral wall (<NUM>) to define, together with the separating line (<NUM>) at least one connecting band (<NUM>; <NUM>) for connecting the closing element (<NUM>) and the retaining portion (<NUM>) to each other; wherein the cap (<NUM>; 1a; 1b; 1c) comprises: a coupling structure (<NUM>; 2a; 2c) positioned inside the lateral wall (<NUM>) for removably coupling the closing element (<NUM>) to the neck of the container, the lateral wall (<NUM>) having a first portion (<NUM>), without the coupling structure (<NUM>; 2a; 2c) and on which the separating line (<NUM>) and the incision line (<NUM>; <NUM>') are made, which has a first height (T1) measured along an axis parallel to the axis (Z) starting from the free edge (<NUM>), and a second portion (<NUM>) provided with the coupling structure (<NUM>; 2a; 2c), which has a second height (T2) measured along an axis parallel to the axis (Z) starting from the transversal wall (<NUM>); wherein the ratio between the second height (T2) and the first height (T1) is greater than or equal to <NUM> and is less than or equal to <NUM> so that the connecting band (<NUM>, <NUM>) can be made in the first portion (<NUM>) with suitable dimensions; and characterized in that at a distance from the free edge (<NUM>) equal to the first height (T1) there is a transition from the first portion (<NUM>) to the second portion (<NUM>), the separating line (<NUM>), or the incision line (<NUM>), being positioned at a distance less than or equal to <NUM> from said transition, the transition being where the coupling structure (<NUM>; 2a; 2c) begins.