Patent Description:
Caps for containers are known, which comprise a cylindrical lateral wall or skirt on an inner surface of which one or more anchoring elements are made, for example threads, suitable for allowing the cap to be removably fastened to a neck of the container. The prior art caps furthermore comprise a flat upper wall, having a substantially circular shape in plan view, from which the cylindrical lateral wall projects.

One or more sealing lips may project from the flat upper wall, the sealing lip(s) extending towards the inside of the cap and being intended to engage with a container neck, so as to obstruct passage of substances from the inside of the container to the outside or vice versa.

It is desirable that the caps for containers have a sufficient rigidity to keep the container well closed even in the presence of deformations which may occur during the life of the container closed by the cap. More specifically, relatively high pressures may be generated inside the container, for example because the container is exposed to relatively high temperatures, or because the container is accidentally deformed and crushed.

It is further desirable that the cap guarantees good sealing properties, that is to say, it prevents the escape of substances contained in the container and the entry into the container of extraneous substances coming from the outside environment.

Lastly, in recent years, the need has been increasingly felt to reduce the consumption of synthetic polymeric material with which the cap is made, for reasons linked to the protection of the environment and the reduction of pollution. A prior art cap according to the preamble of independent claim <NUM> is known from <CIT>.

Other examples of prior art caps are disclosed in <CIT>, <CIT>, <CIT>.

An object of the invention is to improve the caps for containers, in particular but not exclusively, the caps intended to close containers in which gaseous substances are present.

Another object is to provide a cap for a container which possesses a good structural rigidity.

A further object is to provide a cap for a container which is able to close the container in a substantially hermetic manner.

Another object is to provide a cap made of polymeric material, in which the consumption of polymeric material compared with the prior art caps is reduced.

According to the invention, there is provided a cap for a container, comprising an end wall, a skirt which extends about an axis, a corner zone interposed between the end wall and the skirt, the corner zone comprising a first wall portion which projects from the skirt towards the inside of the cap and a second wall portion which protrudes from the end wall and joins the first wall portion, wherein the cap further comprises an annular sealing lip which extends towards a free edge of the skirt from a region in which the first wall portion is joined to the second wall portion.

The annular sealing lip is suitable for engaging, in use, with the neck of the container, by coming into contact with an outer lateral surface of the neck, in such a way that a sealing action is exerted between the annular sealing lip of the cap and the outer lateral surface of the neck.

Thus, the annular sealing lip gives the cap good sealing properties, since it is able to engage with the outer lateral surface of the neck not only when the cap is undeformed, but also when the cap deforms, for example because a relatively high pressure has been generated inside the container.

The first wall portion and the second wall portion define a step on an outer surface of the corner zone.

The step makes it possible to eliminate material in a connecting zone between the end wall and the skirt, thus guaranteeing a saving in the use of polymeric material with respect to the case in which the end wall is joined to the skirt along a full corner.

In an embodiment, the edge zone may have a plurality of outer ribs.

The outer ribs may be distributed along the step defined by the first wall portion and by the second wall portion.

The outer ribs, if present, guarantee a good rigidity of the cap and prevent excessive deformations.

The invention can be better understood and implemented with reference to the accompanying drawings which illustrate non-limiting example versions thereof and in which:.

<FIG> shows a cap <NUM> suitable for being removably fixed to a container for closing an open end thereof. The container which the cap <NUM> makes it possible to close may be a bottle intended to contain a liquid, for example a carbonated drink, or a bottle intended to contain a non-carbonated liquid, or a container of another type.

The cap <NUM> is made of polymeric material, for example by moulding. In particular, the cap <NUM> may be made by injection moulding or compression moulding, although other production technologies are not to be excluded. The cap <NUM> comprises a lateral wall or skirt <NUM>, which extends about an axis Z. According to the example shown, the skirt <NUM> is substantially cylindrical. When the cap <NUM> is applied on a neck of the container, the skirt <NUM> is substantially vertical.

The skirt <NUM> is provided, on an inner surface thereof, with one or more anchoring elements <NUM> which allow the cap <NUM> to be removably fixed to a neck of the container to be closed. According to the example shown, the anchoring elements <NUM> comprise a plurality of portions of thread suitable for engaging with corresponding threads made on the neck of the container. According to an alternative embodiment not illustrated, the anchoring elements <NUM> may have a shape different from the portions of thread shown in <FIG>. For example, the anchoring elements <NUM> might comprise beads or cam elements.

The cap <NUM> further comprises an end wall <NUM> positioned transversally, in particular perpendicularly, to the axis Z. The end wall <NUM> is substantially flat and has a substantially circular shape in plan view.

The end wall <NUM> closes the skirt <NUM> at one end of the skirt <NUM>. At a further end of the skirt <NUM> opposite the end closed by the end wall <NUM>, the skirt <NUM> has a free edge <NUM>.

When the cap <NUM> is applied on a container neck, the end wall <NUM> is positioned at a height greater than the skirt <NUM>, so as to close an open upper end of the container. The end wall <NUM> may therefore be defined as an upper wall of the cap <NUM>, the adjective "upper" referring to the position of the end wall <NUM> during use.

An corner zone <NUM> is interposed between the skirt <NUM> and the end wall <NUM>. The corner zone <NUM> is shown in detail in the enlarged portion of <FIG>.

The corner zone <NUM> comprises a first wall portion <NUM> which projects towards the inside of the cap <NUM> from the skirt <NUM>. The first wall portion <NUM> extends about the axis Z. The first wall portion of <NUM> is positioned transversally relative to the axis Z. The first wall portion <NUM> projects towards the inside of the cap <NUM>, that is to say, towards the axis Z, from an upper edge zone of the skirt <NUM>.

The first wall portion <NUM> is tilted relative to the skirt <NUM>.

The first wall portion <NUM> has an overall shape like a truncated cone or a substantially flat circular crown, concentric with the axis Z.

The corner zone <NUM> further comprises a second wall portion <NUM> which is interposed between the first wall portion <NUM> and the end wall <NUM>. More specifically, the second wall portion <NUM> connects the first wall portion <NUM> to a peripheral edge of the end wall <NUM>.

Also the second wall portion <NUM> extends about the axis Z.

The second wall portion <NUM> has an inclination different from the first wall portion <NUM>. In particular, the second wall portion <NUM> may be less tilted, that is to say, arranged in a configuration closer to a vertical configuration, than the first wall portion <NUM>. The adjective "vertical" is used here with reference to the position which the cap adopts when it is applied on a container, in which the axis Z is substantially vertical and the end wall <NUM> is positioned at a height greater than the skirt <NUM>.

According to the example shown, the second wall portion <NUM> is substantially vertical.

The first wall portion <NUM> may have a thickness which decreases from the skirt <NUM> towards the second wall portion <NUM>, or a substantially constant thickness.

The first wall portion <NUM> and the second wall portion <NUM>, which have different inclinations to each other, define a step in the corner zone <NUM>, in particular on an outer surface of the corner zone <NUM>.

The term "step" does not imply that the first wall portion <NUM> and the second wall portion <NUM> are substantially perpendicular to each other, as shown for example in <FIG>.

In a cross section taken on a plane containing the axis Z, the first wall portion <NUM> extends transversely to the second wall portion <NUM>.

The cap <NUM> comprises an annular sealing lip <NUM> which projects towards the free edge <NUM> from a region in which the first wall portion <NUM> is joined to the second wall portion <NUM>. The annular sealing lip <NUM> protrudes towards the at least one anchoring element <NUM> inside the cap <NUM> to engage with a neck of the container on which the cap <NUM> is applied, as described in more detail below.

The annular sealing lip <NUM> extends about the axis Z. More specifically, in the example shown the annular sealing lip <NUM> extends mainly parallel to the axis Z. If the cap <NUM> is positioned as shown in <FIG>, in such a way that the axis Z is positioned vertically, the annular sealing lip <NUM> extends mainly vertically.

The annular sealing lip <NUM> extends like a continuation of the second wall portion <NUM> towards the inside of the cap <NUM>. The annular sealing lip <NUM> is delimited by an inner surface <NUM> which defines a continuation, without discontinuity, of an inner surface <NUM> delimiting the second wall portion <NUM> inside the cap <NUM>.

The annular sealing lip <NUM> protrudes towards the free edge <NUM> relative to the first wall portion <NUM>.

The annular sealing lip <NUM> has a thickness which decreases towards the free edge <NUM>.

Optionally, the inner surface <NUM> which delimits the annular sealing lip <NUM> is a curved surface, for example having an internal diameter which increases in a direction directed from the end wall <NUM> towards the free edge <NUM>.

The annular sealing lip <NUM> is further delimited by an outer surface <NUM> which may, for example, have the shape of a cylinder coaxial with the axis Z, or a truncated cone shape.

In the example of <FIG>, the annular sealing lip <NUM> has a root portion <NUM>, positioned closer to the second wall portion <NUM>, having a substantially constant thickness, and an end portion <NUM>, positioned further away from the second wall portion <NUM>, having a thickness which decreases towards the free edge <NUM>.

The inner surface <NUM> of the annular sealing lip <NUM> is suitable for engaging with an outer lateral surface of the neck of the container, in order to apply a sealing action in contact with the neck of the container.

The cap <NUM> may comprise a plurality of outer ribs <NUM> arranged in the corner zone <NUM> outside the first wall portion <NUM> and the second wall portion <NUM>. Each outer rib <NUM> joins the first wall portion <NUM> to the second wall portion <NUM>.

The outer ribs <NUM> have a substantially flat shape. Each outer rib <NUM> extends mainly in a plane containing the axis Z. The outer ribs <NUM> are therefore radial ribs.

The outer ribs <NUM> have a rounded outer profile.

The outer ribs <NUM> have a thickness which is substantially constant between one rib and the other, as well as along the single rib.

The outer ribs <NUM> may be angularly equidistant.

The outer ribs <NUM> protrude outwards from the step defined between the first wall portion <NUM> and the second wall portion <NUM>.

A recess <NUM> is interposed between two consecutive outer ribs <NUM>.

Each recess <NUM> is delimited by the first wall portion <NUM> and by the second wall portion <NUM>, as well as by the two outer ribs <NUM> between which it is interposed.

Consequently, it is possible to identify, in the corner zone <NUM> of the cap <NUM>, a plurality of recesses <NUM> which can be distributed in an angularly equidistant manner about the axis Z.

The recesses <NUM> may have an angular extension about the axis Z equal between one recess <NUM> and the other.

The outer ribs <NUM> are optional. According to an embodiment not illustrated, the outer ribs <NUM> might be absent.

The cap <NUM> may further be provided with an inner sealing element <NUM>, having an annular shape, which projects from the end wall <NUM> towards the inside of the cap <NUM>, more specifically towards the free edge <NUM>. The inner sealing element <NUM> is suitable for being inserted inside the neck of the container to sealingly engage with the inner lateral surface of the neck. In particular, the inner sealing element <NUM> may be delimited by a convex sealing surface <NUM> for coming into contact with the lateral inner surface of the neck of the container.

The inner sealing element <NUM> is positioned inside the annular sealing lip <NUM>, that is to say, it has an average diameter less than the average diameter of the annular sealing lip <NUM>.

The inner sealing element <NUM> has a height H1 greater than the height of the annular sealing element <NUM>. This means that the inner sealing element <NUM> has a free end <NUM> closer to the free edge <NUM> with respect to an end <NUM> of the annular sealing lip <NUM>.

The cap <NUM> may comprise a front sealing element <NUM>, shaped like an annular protrusion which projects from the end wall <NUM> towards the inside of the cap <NUM>. The front sealing element <NUM> is interposed between the annular sealing lip <NUM> and the inner sealing element <NUM>. In other words, the front sealing element <NUM> has an average diameter less than the annular sealing lip <NUM>, but greater than the average diameter of the inner sealing element <NUM>.

The front sealing element <NUM> is shorter than the annular sealing lip <NUM> and the inner sealing element <NUM>, so as to engage with an upper edge <NUM> of the neck of the container, shown in <FIG>.

In an embodiment, the front sealing element <NUM> may be omitted.

Knurling lines <NUM> may be present on an outer surface of the skirt <NUM> to make it simpler both to apply the cap <NUM> to a container in an automatic capping line and to grip the cap <NUM> by the user, when the cap <NUM> must be removed from the container or applied to the container.

The knurling lines <NUM> may have the shape of rows in relief which project from the outer surface of the skirt <NUM>, parallel to the axis Z.

As shown in <FIG>, the knurling lines <NUM> may further be grouped together in groups, two adjacent groups of knurling lines <NUM> being separated by a smooth portion <NUM> (that is to say, not knurled) of outer surface of the skirt <NUM>. In the example of <FIG>, the groups of knurling lines <NUM> are formed by three knurling lines <NUM>.

Alternatively, the knurling lines <NUM> may be distributed according to other arrangements, for example they can be distributed equidistantly about the axis Z.

The knurling lines <NUM> may extend as a continuation, along the skirt <NUM>, of all or a part of the outer ribs <NUM>. In the latter case, as shown in <FIG>, the outer ribs <NUM> from which the knurling lines <NUM> extend can project towards the outside of the cap <NUM> more than the other outer ribs <NUM>.

Furthermore, at least one separation line <NUM>, shown in <FIG>, may be provided on the skirt <NUM>, that is to say, a breakable line along which the material which forms the cap <NUM> can break the first time the container closed by the cap <NUM> is opened. The separation line <NUM> defines on the cap <NUM> a tamper evident ring <NUM> and a closing element <NUM>. The tamper evident ring <NUM> is interposed between the separation line <NUM> and the free edge <NUM> and is suitable for remaining anchored to the neck of the container after the container has been opened. The closing element comprises the end wall <NUM> and a portion of the skirt <NUM> interposed between the end wall <NUM> and the separation line <NUM>. The closing element <NUM> may be removed from the container to access its contents or alternatively reapplied on the container. The separation line <NUM> may be defined by a plurality of cuts between which respective bridge elements are interposed. The bridge elements are suitable for being broken the first time the closing element <NUM> is removed from the container, thereby signalling that the container has already been opened.

Alternatively, the separation line <NUM> may be defined by one or more portions of thin thickness in which the material forming the cap <NUM> has a thickness less than in the rest of the skirt <NUM>.

The separation line <NUM> may be obtained in different ways, for example by a cutting operation performed after the cap <NUM> has been moulded, or directly during moulding.

The tamper evident ring <NUM> may comprise an annular band <NUM>, delimited by the separation line <NUM> and extending up to the free edge <NUM>. The tamper evident ring <NUM> may further comprise a retaining element <NUM>, suitable for engaging with the neck of the container to prevent the tamper evident ring <NUM> from being removed from the container when the container is opened for the first time. According to the example shown, the retaining element <NUM> comprises a flap connected to the annular band <NUM> at the free edge <NUM> and folded upwards inside the cap <NUM>, so as to be surrounded by the annular band <NUM>. The retaining element <NUM> is suitable for interacting with an annular protrusion located outside the neck of the container.

The retaining element <NUM> may also be shaped differently from what is indicated in <FIG>. For example, the retaining element <NUM> may comprise a plurality of tabs folded towards the inside of the cap <NUM>, or a plurality of beads which project from an inner surface of the annular band <NUM> towards the inside of the cap <NUM>.

The cap <NUM> may have one or more vent passages <NUM>, one of which is shown in <FIG>. The vent passage <NUM> is intended to allow a controlled and gradual escape of any pressurised gas present inside the container, whilst the closing element <NUM> is removed from the container, for example by unscrewing. The vent passage <NUM> may be shaped like an axial groove, extending parallel to the axis Z, at which the anchoring elements <NUM> are interrupted.

<FIG> shows a vent passage <NUM> which interrupts all the anchoring elements <NUM> provided in the angular position (about the axis Z) in which the vent passage <NUM> is located.

As an alternative to the vent passage <NUM> of the type described above, or in addition to the vent passage <NUM>, it is possible to provide one or more partial interruptions <NUM> which, as shown in <FIG>, interrupt only partly the anchoring elements <NUM>. In the example of <FIG>, the partial interruptions <NUM> interrupt only a portion of thread closest to the tamper evident ring <NUM>, leaving unaltered a further portion of thread closer to the end wall <NUM>.

The partial interruptions <NUM> have a vent function, that is to say, they allow the escape of gas possibly present in the container, even though in a more limited manner than the vent passages <NUM>.

The partial interruptions <NUM> may be positioned in respective angular positions, about the axis Z, different from the angular positions in which the vent passages <NUM> are positioned.

The cap <NUM> is intended to be applied on a neck <NUM> of a container, as shown in <FIG>.

The neck <NUM>, which is also visible in <FIG>, may comprise a fastening arrangement <NUM> suitable for allowing the closing element <NUM> of the cap <NUM> to be fastened to the neck <NUM> or removed from the latter. The fastening arrangement <NUM> may comprise one or more outer threads made on the neck <NUM> and suitable for engaging with the anchoring elements <NUM> of the cap <NUM>.

As shown in <FIG>, the neck <NUM> may further comprise an annular element <NUM>, which projects from the neck <NUM> towards the outside and which can perform various functions. For example, the annular element <NUM> may be used for transporting the container during its production and during filling. Moreover, the annular element <NUM> acts as a stop element for the tamper evident ring <NUM>, since it prevents the tamper evident ring <NUM> from falling along the neck <NUM> below the annular element <NUM>, after the closing element <NUM> has been detached from the tamper evident ring <NUM>. Between the annular element <NUM> and the fixing arrangement <NUM> an annular enlargement <NUM> is interposed, the annular enlargement <NUM> projecting outwards from the neck <NUM> and being suitable for engaging with the retaining element <NUM> of the tamper evident ring <NUM>, as described in more detail below.

In use, the container is filled with the liquid or another desired substance, after which the cap <NUM> is applied on the neck <NUM>.

The anchoring elements <NUM> engage with the fastening arrangement <NUM> to keep the cap <NUM> in a closed position.

The retaining element <NUM> made on the tamper evident ring <NUM> is positioned below the annular enlargement <NUM>.

The annular sealing lip <NUM> is positioned outside the neck <NUM>, that is to say, it surrounds an end portion of the neck <NUM>.

The inner surface <NUM> of the annular sealing lip <NUM> is in contact with an outer lateral surface of the neck <NUM>. In particular, the annular sealing lip <NUM>, which is flexible, may bend slightly outwards when it engages with the neck <NUM>. The inner sealing element <NUM> is positioned inside the neck <NUM>, in such a way that the convex sealing surface <NUM> is in contact with an inner lateral surface of the neck <NUM>. More specifically, the inner sealing element <NUM> may bend towards the inside when it is inserted inside the neck <NUM>.

An end portion of the neck <NUM> is thus inserted between the annular sealing lip <NUM> and the inner sealing element <NUM>.

An upper edge of the neck <NUM> abuts against the front sealing element <NUM> which, if present, ensures that the neck <NUM> has penetrated in the cap <NUM> by the correct amount.

The annular sealing lip <NUM>, the inner sealing element <NUM> and the front sealing element <NUM> prevent the substances, particularly gaseous ones, present inside the container from escaping into the outside environment and, at the same time, prevent the substances present in the outside environment from entering the container. The integrity and properties of the liquid or other substance present in the container are thus preserved. The cap <NUM> is able to close the container in a substantially hermetic manner even when pressures develop inside the container such as to cause a swelling of the cap <NUM>, in particular of the end wall <NUM> which, as shown in <FIG>, may in this case adopt a dome-shaped configuration <NUM>. These pressures, which are originated easily in particular when the cap <NUM> is used to close a container containing a carbonated drink, may, for example, be generated because the container closed by the cap <NUM> is exposed to relatively high temperatures, or because it has been accidentally crushed. If the end wall <NUM> deforms, adopting the dome-shaped configuration <NUM> of the type shown in <FIG>, the annular sealing lip <NUM>, which is flexible, bends and deforms in such a way as to guarantee in any case contact with the neck <NUM> of the container, so that the sealing action exerted by the annular sealing lip <NUM> still remains present.

More specifically, the annular sealing lip <NUM> and the inner sealing element <NUM> remain in contact with the neck <NUM> even when the pressure inside the container increases until causing detachment of the front sealing element <NUM> from the neck <NUM>, more specifically from the upper edge <NUM> of the neck <NUM>, as shown in <FIG>.

The inner sealing element <NUM> also deforms, for example adopting a tilted configuration in a different manner from that shown in <FIG>. The contact between the convex sealing surface <NUM> and the neck <NUM> is in any case maintained.

Owing to the recesses <NUM>, the first wall portion <NUM> and the second wall portion <NUM> allow a corner zone <NUM> to be obtained which is lightened relative to the case in which the corner zone <NUM> is solid, that is to say, where no recesses <NUM> are provided between consecutive outer ribs <NUM>. This makes it possible to limit the quantity of polymeric material to be used for producing the cap <NUM>.

The outer ribs <NUM> allow the corner zone <NUM> to be stiffened, ensuring that the rigidity is sufficient practically for the main industrial requirements.

Moreover, the first wall portion <NUM> guarantees a good resistance in cases in which the skirt <NUM> tends to widen, for example because it is pushed towards the outside due to the effect of the thermal expansion of the neck <NUM>, linked to the high temperatures to which the neck <NUM> can be subjected. Given the tilted configuration of the first wall portion <NUM>, in order to deform the first wall portion <NUM> it is necessary that a component of the force applied to the first wall portion <NUM> compresses the first wall portion <NUM> in its direction of main extension, that is to say, transversely to the axis Z, which requires relatively high forces.

<FIG> shows a cap <NUM> according to an alternative embodiment, which differs from the cap <NUM> shown in <FIG> and <FIG> mainly because it comprises an inner sealing element <NUM> having a height H2 less than the corresponding height of the inner sealing element <NUM> included in the cap <NUM>, with other dimensions being the same.

Both in the cap <NUM> shown in <FIG> and in the cap <NUM> shown in <FIG>, the thickness of the end wall <NUM> may be varied according to the specific requirements of the combination of the cap with the container which the cap is intended to close.

When the container closed by the cap <NUM>, <NUM> is stored, for example inside a storage unit or a container, high temperatures may be reached, even greater than <NUM>, due in particular to exposure to the sun or the high external temperatures.

At these temperatures, the material which forms the neck <NUM> can soften, especially if the container is made of amorphous materials such as polyethylene terephthalate. The cap, which is usually made of semicrystalline materials, which maintain a greater rigidity even at relatively high temperatures, is, on the other hand, stiffer and, under the action of high pressures generated inside the container, can deform and thus deform the neck <NUM>, damaging it.

In order to prevent this from happening, it is possible to select, during the design of the cap, the thickness of the end wall <NUM> in such a way that the end wall <NUM> allows the gases present in the container to escape at least partly, so that the pressure present in the container decreases and permanent damage to the container by the cap <NUM>, <NUM> is avoided.

In particular, it is possible to suitably select the thickness of the end wall <NUM> in some predetermined zones, such as, for example, in a central zone <NUM> of the end wall <NUM>, close to the axis Z, and in a peripheral zone <NUM> of the end wall <NUM>, close to the annular sealing lip <NUM>.

The thickness of the end wall <NUM> may be constant, which means that, in the central zone <NUM>, the thickness of the end wall <NUM> is equal to the thickness of the end wall <NUM> in the peripheral zone <NUM>.

Alternatively, different zones of the end wall <NUM> may have different thicknesses. For example, the thickness of the end wall <NUM> in the central zone <NUM> may be different (greater or smaller) from the thickness of the end wall <NUM> in the peripheral zone <NUM>.

If the container closed by the cap <NUM>, <NUM> contains a carbonated drink, the thickness of the end wall <NUM> may vary from <NUM> to <NUM>, more specifically from <NUM> to <NUM>.

If the thickness of the end wall <NUM> in the central zone <NUM> is different from the thickness of the end wall <NUM> in the peripheral zone <NUM>, the difference between these two thicknesses may vary from <NUM> to <NUM>, more specifically from <NUM> to <NUM>.

If the container closed by the cap <NUM>, <NUM> is intended to contain a carbonated drink, the skirt <NUM> may have a thickness S of between <NUM> and <NUM>, more specifically between <NUM> and <NUM>.

As shown in <FIG>, the thickness S is measured between an outer surface of the skirt <NUM> (in particular an outer surface from which the knurling lines <NUM> protrude, if present) and an inner surface of the skirt <NUM> from which the at least one anchoring element <NUM> protrudes.

The vent passages <NUM> and/or the interruptions <NUM> may be shaped as recesses having a depth of between <NUM> and <NUM>. If the depth of the vent passages <NUM> and/or of the interruptions <NUM> is equal to <NUM>, the vent passages <NUM> and/or the interruptions <NUM> are zones in which the anchoring elements <NUM> are not present.

More specifically, the depth of the vent passages <NUM> and/or of the interruptions <NUM> may be between <NUM> and <NUM>.

If the anchoring element <NUM> comprises an inner thread made on the cap, suitable for engaging with an outer thread made on the neck <NUM>, the inner thread and the outer thread may have angular extensions different to each other.

In particular, the inner thread present on the cap may have an angular extension greater than the angular extension of the outer thread present on the neck.

More specifically, in the case of caps <NUM>, <NUM> intended to be applied to containers having a volume greater than one litre, when the cap <NUM>, <NUM> is screwed on the neck <NUM>, the inner thread present on the cap can continue towards the free edge <NUM> beyond the outer thread present on the neck <NUM>. The inner thread present on the cap <NUM>, <NUM>, which is screwed on the neck <NUM>, can continue beyond the outer thread present on the neck <NUM>, towards the free edge <NUM>, for an angular extension of between <NUM>° and <NUM>°, in particular between <NUM>° and <NUM>°.

In addition or alternatively to the above, it may occur that, when the cap <NUM>, <NUM> is screwed to the neck <NUM>, the inner thread formed on the cap extends beyond the outer thread formed on the neck, towards the end wall <NUM>, for an angular extension of between <NUM>° and <NUM>°, for example between <NUM>° and <NUM>°.

The cap <NUM>, <NUM>, or caps having a similar structure, may be applied to all the necks for carbonated drinks currently used.

In particular, the cap according to the invention may be applied to the low necks recently introduced, that is to say, to necks having a height X of between <NUM> and <NUM> and an internal diameter C (see <FIG>), in an opening zone, equal to approximately <NUM>.

As shown in <FIG>, the height X is the distance between a lower surface of the annular element <NUM> and the upper edge <NUM> of the neck <NUM>.

The cap according to the invention may be applied both to necks having a single thread (that is to say, a thread extending along a single spiral), and to necks having more than one thread, for example to necks having two threads.

It is further possible to apply the cap according to the invention to necks having a nominal diameter equal to <NUM>, for example necks with a height X of approximately <NUM>, outer diameter T of the thread of approximately <NUM> (see <FIG>) and inner diameter C of the neck, in the opening zone, of approximately <NUM>.

The cap according to the invention may further be used in combination with lower necks such as the so-called "<NUM>" necks, for example necks with a height X of approximately <NUM> and an internal diameter C, in the opening zone, equal to approximately <NUM>.

Further, the cap according to the invention may be applied on special necks, for example of the type having a height X of approximately <NUM>, an inner diameter C, in the opening zone, equal to <NUM> and an outer diameter T of the thread of approximately <NUM>.

For a neck having a height X of approximately <NUM> and an outer diameter T of the thread of approximately <NUM>, intended to be applied on a container for carbonated drinks, it is possible to use a cap of the type described above having a minimum height of approximately <NUM> and an outer diameter approximately between <NUM> and <NUM>.

In general, the cap <NUM>, <NUM>, or a similar cap, may have a weight of between <NUM> and <NUM> grams, if intended to be applied to a container containing a carbonated drink.

The cap <NUM>, <NUM>, or a similar cap, may have a weight of between <NUM> and <NUM> grams, if intended to be applied to a container containing a non-carbonated drink.

The caps described above are made of polymeric 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 produce the caps described above can have the following properties:.

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

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

The caps of the type described above are suitable for use, for example, on the necks shown in the following list, each neck being associated with a respective nomenclature 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, as per CETIE (www. org) or ISBT (www. org) nomenclature.

For each acronym, if the neck is also a European standard, the reference number is also indicated.

Claim 1:
A cap for a container, comprising an end wall (<NUM>), a skirt (<NUM>) which extends about an axis (Z), a corner zone (<NUM>) interposed between the end wall (<NUM>) and the skirt (<NUM>), the corner zone (<NUM>) comprising a first wall portion (<NUM>) which projects from the skirt (<NUM>) towards the inside of the cap (<NUM>) and a second wall portion (<NUM>) which protrudes from the end wall (<NUM>) and is joined to the first wall portion (<NUM>), the first wall portion (<NUM>) and the second wall portion (<NUM>) defining a step on a surface of the corner zone (<NUM>) facing towards the outside of the cap (<NUM>; <NUM>), wherein the cap (<NUM>) further comprises an annular sealing lip (<NUM>) delimited by an inner surface (<NUM>), wherein the annular sealing lip (<NUM>) extends towards a free edge (<NUM>) of the skirt (<NUM>) from a region in which the first wall portion (<NUM>) is joined to the second wall portion (<NUM>), characterized in that the inner surface (<NUM>) is configured to engage with an outer lateral surface of the neck (<NUM>) of the container.