Closure for a sealed container of a pourable food product, and method of producing thereof

There is described a closure for a sealed container of a pourable food product, comprising a pouring spout defining a pour opening externally closed by a cover portion, a cap fitted to the pouring spout in a removable way, an opening member interposed between the cap and the cover portion of the pouring spout and joined to the cover portion, and a driving mechanism carried by the cap to engage and pull the opening member along a direction transversal thereto upon removal of the cap from the pouring spout so as to detach the cover portion from the neck portion and free the pour opening when the closure is first unsealed by the user.

TECHNICAL FIELD

The present invention relates to a closure for a sealed container of a pourable food product, and to a method of producing thereof.

BACKGROUND ART

As it is known, many pourable food products, such as fruit juice, milk, tomato sauce, and beverages in general, are sold in a wide range of containers of different types and sizes, such as: parallelepiped-shaped packages made of multilayer, plastic- and/or paper-based, laminated materials or so-called multilayer cardboard materials; beaker-shaped plastic packages; blow-molded bottles; or glass, sheet metal or aluminium containers.

All these containers are fitted with closures which can be opened to allow access by the consumer to the food product, either to pour it into a drinking vessel or consume it straight from the container.

Screw cap closures are commonly used on bottle-type containers, whereas containers made of multilayer cardboard materials are often simply provided with tear-off markers, or with pour openings formed in the containers and covered with pull tabs.

Containers made of multilayer cardboard materials are also known to be fitted with plastic closures injection molded directly onto the containers, about openings formed through the packaging material, so as to completely close and seal the openings. Closures of this sort normally define the pour opening of the container, which may be fitted, for example, with a screw or snap cap.

Injection molded closures may of course be of various sizes and even define the whole top of the container, as in the case of the container known by the registered trademark “Tetra Top”, and the top of which is illustrated in Patent Application EP-A-0965531.

Though permitting precise, high-quality forming, injection molding container tops does not allow for integrating a layer of gas-barrier material in the tops, as required, for example, when packaging vitamin-supplemented fruit juice.

As described, for example, in Patent EP-B-1197438 and Patent Application WO 03/061940, plastic tops of containers are also known to be produced by blowing a plastic tubular preform, which may include a layer of gas- and also light-barrier material.

The container known by the trademark “Tetra Aptiva” is one example of a container produced using this technique, i.e. having a main bottom portion made of multilayer cardboard material, and a top, for pouring the liquid or pourable product in the container, produced by blowing a plastic tubular preform.

This technique provides for a high degree of forming precision, especially as regards the pour opening, but has the drawback of requiring the use of special-purpose equipment.

To produce plastic tops or closures to be applied to the container portion of multilayer cardboard material, a method has recently been devised comprising thermoforming and injection molding operations, but no blowing.

One example of this method is described in Patent Application WO 2005/044538, and comprises the step of thermoforming a sheet body of multilayer plastic material having a layer of gas-barrier material, e.g. EVOH. The body is defined integrally by an annular base portion, which is eventually fitted to the cardboard bottom portion of the container, and by a cylindrical neck portion projecting from the inner edge of the base portion and defining, with the base portion, a pour opening by which to pour out the food product. Since thermoforming is performed starting from a sheet of plastic material, the neck portion is closed at its side opposite to the base portion. A protective outer layer of plastic material, with a lateral thread to screw on a cap, is injection molded onto the sheet body so as to form a pouring spout for the container.

After the above operations, and before applying the cap, the material closing the pour opening is removed.

In order to achieve a gas-tight closure of the resulting pouring spout after filling the container, an aluminum foil is welded to the top edge of the spout. After this operation, the cap is finally screwed on the pouring spout.

The above method of producing plastic tops or closures for combined cardboard-plastic containers mainly has the drawback of involving a good deal of time, work, and waste in costly material.

In fact, the portion of material closing the pour opening after the thermoforming operation, and which is removed before applying the cap, normally amounts to about 15-20% of the starting material and, in addition, has a considerable cost as, differently from commonly used plastic materials such as polyethylene or polypropylene, it contains a gas-barrier layer.

Moreover, the aluminum foil welded to the top edge of the pouring spout to achieve a gas-tight closure constitutes a costly additional member, which must be produced and fitted to the spout before the cap is applied to the container.

Furthermore, the resulting closure requires an annoying two-steps operation by the user to obtain the first unsealing. In fact, it is necessary first to unscrew the cap from the pouring spout and then to tear off the aluminum foil covering the spout to reach the content.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a closure for a sealed container of a pourable food product, which is designed to eliminate the aforementioned drawbacks in a straightforward and low-cost manner.

It is another object of the present invention to provide a closure for a sealed container of a pourable food product, which is capable of ensuring an effective gas- and/or light-barrier and allows to reduce the waste in costly material during its producing process as well as to obtain the first unsealing in a reliable and easy way through a single-step operation and with reduced effort by the user.

At least one of these objects is achieved by a closure for a sealed container of a pourable food product, as claimed in claim1.

The present invention also relates to a method of producing a closure for a sealed container of a pourable food product, as claimed in claim23.

BEST MODE FOR CARRYING OUT THE INVENTION

Number1inFIGS. 1-4indicates as a whole a closure for a container (not shown) of liquid or pourable food products, such as a plastic closure for a combined cardboard-plastic container—to which the following description refers purely by way of example.

Closure1has a longitudinal axis A and basically comprises a pouring spout2, having at least a layer of gas- and/or light-barrier material, e.g. EVOH, and defining a pour opening3, by which to pour the food product out of the container, and a cylindrical cap4fitted to pouring spout2in a removable way.

More specifically, pouring spout2comprises an annular base portion5, which, in the example shown, is concave inwards of the container, and a substantially cylindrical tubular neck portion6, which projects from an inner radial edge7of base portion5, and defines, with base portion5, pour opening3.

According to a possible alternative not shown, base portion of pouring spout2may be also configured to define integrally a complete top or end wall of the container.

Cap4is produced in a single piece and is substantially defined by a cylindrical lateral wall8, which has an internal thread9, with one or more starts, for engaging a corresponding thread10provided on an outer lateral surface of neck portion6, and by a disk-shaped top wall11for covering, in use, the top of pouring spout2.

In an alternative embodiment not shown, lateral wall8of cap4may be internally provided with a plurality of cam projections suitable for engaging corresponding projections on neck portion6.

In practice, in both cases, cap4is fittable to and removable from pouring spout2along a stroke having a translational component parallel to axis A and a rotational component about such axis.

Cap4is molded integrally, in the usual way, with a respective tamperproof ring12connected coaxially to a bottom edge13of lateral wall8by breakable connecting means14, such as one annular breakable bridge or a number of radial breakable bridges.

Cap4is fitted initially to pouring spout2in a completely closed or sealed position (FIG. 1), wherein the cap is screwed completely onto neck portion6, with bottom edge13and tamperproof ring12still connected to each other and resting on opposite sides of a bottom portion of thread10of neck portion6or an annular rib extending on the neck portion at a lower position than thread10with respect to axis A.

Once unsealed, cap4is movable between an open position (FIG. 2), in which it is unscrewed off pouring spout2, and a closed-again position, in which it is completely screwed on the pouring spout so as to reseal pour opening3.

As described in greater detail below, pouring spout2is produced, and attached to the container, in a closed configuration, in which a disk-shaped cover portion15, integral with neck portion6, closes pour opening3on the side of neck portion6opposite to the side facing, in use, the container; when cap4is first removed by pouring spout2, i.e. when the container is first unsealed by the user, cover portion15is detached from neck portion6as a result of the movement of cap4so freeing pour opening3.

Advantageously, such action of cap4on cover portion15is performed through a disk-shaped opening member16, which is joined, for instance by welding, to cover portion15and is engaged and pulled along axis A by an upper portion of thread9or other suitable driving means of cap4during removal thereof from pouring spout2.

In particular, opening member16is interposed between top wall11of cap4and cover portion15when joined to the latter, and is free from any rotational connection with cap4.

Opening member16has an outer edge17protruding radially with respect to the top surface of pouring spout2so as to be engaged by the upper portion of thread9, i.e. the portion of thread9adjacent to such outer edge, when cap4is unscrewed from neck portion6; outer edge17is rounded and is bent towards neck portion6so as to extend over a top edge18thereof.

As clearly visible in particular inFIGS. 2 and 3, top wall11of cap4, the upper portion of thread9and the part of lateral wall8of the cap limited therebetween define a retaining seat20for opening member16to prevent the latter from unintentionally coming off the cap.

The particular shape of outer edge17of opening member16eases engagement with driving means and insertion in retaining seat20of cap4.

In particular, opening member16is retained inside seat20of cap4with a given play in the radial and axial directions so as to freely rotate about axis A and to move substantially along such axis between top wall11and the upper portion of thread9of the cap.

As shown inFIGS. 1,2and4, opening member16has a first annular ridge21, along which it is welded to cover portion15of pouring spout2, and a second annular ridge22, which extends between annular ridge21and outer edge17and defines a contact portion cooperating with top edge18of neck portion6in the completely closed and closed-again positions of cap4so as to ensure resealing of closure1even after the first unsealing of the container.

Closure1is produced according to the method described below.

Firstly, a forming operation, preferably a thermoforming or hot forming operation, is performed on a multilayer plastic sheet material comprising a layer of gas- and/or light-barrier material, e.g. EVOH.

The forming operation produces a hollow, substantially hat-shaped body25, which is open on the side facing the container to which it is eventually attached, and is closed on the opposite side.

More specifically, body25comprises an annular bottom portion integrally defining base portion5, and an inverted cylindrical cup-shaped top portion26projecting axially from the inner radial edge of the bottom portion. Top portion26has a lateral wall defining the inner side of neck portion6, and therefore laterally bounding pour opening3, and a disk-shaped top wall closing pour opening3.

Alternatively, body25may be produced by other suitable forming techniques, such as compression or injection molding.

Body25may be also produced from a plastic material having no gas- and/or light-barrier property, and a layer of gas- and/or light-barrier material may be provided by a surface coating.

Next, plastic material, such as polyethylene or polypropylene, is overmoulded by compression onto the outer side of top portion26of body25to form thread10and other neck features so as to impart sufficient thickness and rigidity to those parts.

All these operations permit to obtain pouring spout2in the configuration shown inFIG. 3.

When forming of pouring spout2is obtained by compression or injection molding, the overmoulding step is not necessary; in fact, compression or injection molding allow forming, in a single step, body25and all neck features, such as thread10.

As a result of the described operations, neck portion6and cover portion15define integral parts of pouring spout2, in the sense that they derive from forming operations only, without any necessity of joining them through welding or gluing.

At the same time, cap4and opening member16are formed singularly through known techniques and then assembled together. In particular, opening member16is pressed into retaining seat20of cap4and is hold in place by thread9.

At this point, the assembly defined by cap4and opening member16is applied to pouring spout2(FIG. 4), so that threads9and10engage mutually, and top wall11of cap4presses opening member16against the top surface of pouring spout2at the annular ridges21and22.

In order to ease detachment of cover portion15from neck portion6during first unsealing of closure1, a weakening circumferential line27is also produced along the periphery of the cover portion.

Preferably (FIG. 4), weakening line27is obtained as a score, i.e. a partial cut, produced on a side27aof cover portion15facing pour opening3or, in an equivalent manner, facing away from top wall11of cap4. The scoring operation can be performed, for instance, by a hot or cold blade or by ultrasonic or laser devices.

In the example shown inFIG. 4, the welding operation and the formation of weakening line27are performed simultaneously by a ultrasonic device28; it substantially comprises a substantially cylindrical tubular pressure member29, having an annular work surface30cooperating with top wall of body25and an ultrasound generating unit (not shown), a backing member31cooperating with top wall11of cap4on the opposite side to pressure member29, and guide means (not shown) for moving pressure member29to and from backing member31to obtain the desired compression force during ultrasound generation.

The outer periphery of pressure member29may be fitted with a cutting member32which acts on cover portion15to make weakening line27.

It is pointed out that pouring spout2, cap4and opening member16could be made of different materials.

According to a possible alternative shown inFIG. 5, performing the weakening operation in a hot state, e.g. by using ultrasonic or laser devices, hot tools, etc., and all through the periphery of cover portion15, it is possible to obtain not only a complete cut23of the material under opening member16, but also a weld24of the top surface of cover portion15to the opening member around the cutting zone. In practice, due to the melting effect on the material around the cutting zone, the weakening operation produces a simultaneous joining of the overlap parts in such zone.

At the end of the above-described operations, cover portion15defines a layer of gas- and/or light-barrier material of cap4, i.e. a “liner”, as this layer is commonly referred to in the packaging of pourable food products.

According to another possible alternative shown inFIG. 6, weakening line27can be obtained as a score produced on a side27bof cover portion15facing in use top wall11of cap4.

In this case, the weakening operation may be performed directly in the overmoulding process of thread10and the other neck features, e.g. by using an annular ridge33or a blade to be pushed into the still soft material in the mold on side27bof cover portion15, and a backing member34acting on opposite side27bof the cover portion to produce the desired contrasting force. As a consequence, only the welding operation has to be performed after assembly of pouring spout2with cap4and opening member16.

Alternatively, the weakening operation may be also performed after the overmoulding operation in a separate station.

In any case, the weakening operation on pouring spout2need to be performed before the pouring spout is assembled with opening member16and cap4.

According to a further possible alternative not shown, the weakening operation may be also performed by producing respective score lines on both sides27a,27bof cover portion15.

According to a still further possible alternative not shown, opening member16may be applied and welded onto cover portion15of pouring spout2and, then, cap4may be fitted to the assembly defined by pouring spout2and the opening member.

This alternative applies whatever side of cover portion15the weakening operation is performed onto.

First unsealing of the container is obtained in a single step by unscrewing cap4off pouring spout2.

As cap4is turned about axis A anticlockwise inFIG. 1, mating threads9and10simultaneously move cap4axially away from pouring spout2so as to break connecting means14; as a result of this action, tamperproof ring12is retained resting axially against the bottom portion of thread10of neck portion6.

At this stage, opening member16, being free from any rotational connection with cap4, is kept still against the top surface of cover portion15it is welded to.

Upon further rotation of cap4with a consequent translation along axis A, the upper portion of thread9engages outer edge17of opening member16and, upon even further rotation of the cap, a vertical force is produced onto opening member16to pull it up along axis A; as of this point, opening member16moves together with cap4along axis A, so producing a breaking action at the weakening line27to detach cover portion15from neck portion6of pouring spout2and to free pour opening3. In practice, opening member16is driven by cap4in a completely translational motion along axis A, while the cap has a roto-translational motion.

When cap4is completely removed from pouring spout2, opening member16and cover portion15are retained within seat20by thread9in a floating condition so as not to come off the cap unintentionally.

By virtue of the weld, cover portion15remains joined to opening member16as opposed to being discarded.

The container can be closed again by simply fitting cap4back onto pouring spout2. In this condition, the resealing of closure1is ensured by cooperation of ridge22with top edge18of neck portion6under the pressure exerted by cap4on pouring spout2in the closed-again position.

The variant ofFIG. 7relates to a different configuration of the driving means of cap4for engaging and pulling opening member16along axis A.

In this case, the driving means comprises an annular protrusion35extending from the inner surface of lateral wall8and, in the example shown, located at a higher level than upper portion of thread9along axis A. Protrusion35may also consist of different elements angularly spaced about axis A and located at the same or different levels with respect to such axis.

The driving means may also be defined by a protrusion of the type shown inFIG. 7but not extending along the entire circumference about axis A and by an upper portion of thread9both cooperating with outer edge17of opening member16to pull it up along axis A during the roto-translational motion of cap4.

The variants ofFIGS. 8 and 9relate to different solutions to ensure, after first removal of cap4from pouring spout2, correct centering of opening member16inside seat20of the cap, and therefore with respect to the pouring spout, when the container is closed again. By maintaining centering, correct resealing of closure1is guaranteed.

In the embodiment ofFIG. 8, opening member16has, along its outer circumference, a thin protruding extension36cooperating with inner surface of lateral wall8of cap4to help keeping the opening member centered inside seat20without impairing assembly of such member with cap4.

In the embodiment ofFIG. 9, opening member16and top wall11of cap4respectively have protrusions37and complementary recesses38mutually engaging to define a centered position of the opening member with respect to the cap in the completely closed and closed-again positions thereof. Each protrusion37and the complementary recess38may also have tapered configurations towards the inner of top wall11to ease their mutual engagement during the final stage of the screwing movement of the cap onto pouring spout2.

It is evident that protrusions37may be also provided on top wall11of cap4and complementary recesses38on opening member16.

The variant ofFIG. 10relates to a different solution of pouring spout2, whose top edge18has a rounded annular ridge40capable of producing a positive sensation to the user's mouth during direct consumption of the product from the container.

In this case, due to the presence of rounded ridge40, the configuration of opening member16is modified; in particular, ridge21of opening member16has a greater height when compared to the above-described solutions so as to be welded to cover portion15, and delimits, with outer edge17, an annular seat39having a U-shaped section for receiving, with a given play, rounded edge40of pouring spout2.

Resealing is obtained through cooperation of ridge22of opening member16and rounded ridge40of pouring spout2.

According to a further possible variant not shown, resealing of closure1may be also obtained by configuring seat39exactly with a shape complementary to that one of rounded edge40of pouring spout2; in this case, ridge22may be not necessary. Besides, this arrangement could also help to ensure a correct centering of opening member16with respect to pouring spout2.

In the variant ofFIG. 11, the resealing of closure1after the first unsealing is ensured by a protruding lip41of cap4which also defines a driving means to engage and pull opening member16along axis A during the first removal of cap4from pouring spout2.

In particular, in this case, opening member16only performs the function of receiving a vertical force from cap4during the first unsealing of closure1and transmitting that force to cover portion15to detach the latter from the rest of pouring spout2.

More specifically, in order to perform both the functions of resealing closure1and driving opening member16in its pull-up movement, top wall11of cap4has an inverted cylindrical cup-shaped configuration with an open end edge42externally connected to lateral wall8through a circular band43and internally provided with protruding lip41.

In greater detail, top wall11of cap4integrally comprises a disk-shaped main portion44, having a diameter greater than the one of pour opening3and extending at a higher level than circular band43with respect to axis A, and a lateral cylindrical portion45connecting main portion44with circular band43and defining, at intersection with the latter, end edge42.

Protruding lip41extends from end edge42respectively towards the top surface of pouring spout2and towards axis A so as to stick out radially of lateral cylindrical portion45.

When cap4is completely screwed onto pouring spout2, protruding lip41is pressed against top edge17of neck portion6so ensuring resealing of closure1.

Opening member16has, in this case, a truncated cone-shaped outer edge46projecting towards lateral cylindrical portion45and main portion44so as to be engaged and pulled along axis A by protruding lip41during first unsealing of closure1.

Engagement between protruding lip41and outer edge46also ensures a correct centering of opening member16with respect to cap4.

The advantages of closure1and the method of producing thereof will be clear from the foregoing description.

Thanks to the fact that sealing of the pouring side of pouring spout2is defined by cover portion15, which is simply obtained through the forming operation for producing the spout, any waste in material is eliminated, particularly when this material has a gas- and/or light-barrier material and is therefore quite costly. In fact, in this case, cover portion15is simply welded to opening member16in order to be then detached from the spout during the first unsealing of the container, instead of being first removed at the end of the forming process of the pouring spout and then replaced by an additional member welded to the spout and which needs to be removed again at the first use.

Moreover, thanks to the use of opening member16, welded to cover portion15of pouring spout2, the first unsealing of closure1can be achieved by the user through a single-step operation and with low effort.

In fact, during rotation of cap4, opening member16is driven by the cap in a pure translational movement along axis A, thereby producing simultaneous detachment of cover portion15from neck portion6through a tensile stress.

The applicant has noted that this kind of stress on the cover portion of the pouring spout permits to achieve the first unsealing of the container with a reduced effort from the user when compared to a shear stress on the full outline of the material to be removed. In a completely equivalent manner, in order to allow the user to first unseal the container through an acceptable opening torque, the use of a tensile stress has a reduced impact on the demand for weakening the breaking zone when compared to a shear stress.

In fact, the applicant has estimated that, in the latter case, a sufficient weakening of the breaking zone requires that the material remaining in the cut (i.e. connecting the two parts to be subsequently detached) be as thin as a few hundredths of a millimeter, with an accuracy of a few thousandths of a millimeter. This can be very difficult to realize in practice.

In the case of the present invention, the applicant has estimated that the demand for weakening the breaking zone is reduced about one order of magnitude.

Moreover, by arranging the driving means (e.g. the upper portion of thread9and/or one or multiple protrusions35) on the cap4at different levels along axis A so as to start engagement with outer edge17of opening member16at one specific point, and to progressively increase the engaging area as the cap is turned, may further reduce the demand for weakening. In fact, in this case, the torque effort required to the user is smaller than that one in the case of driving means all located at the same level along axis A.

Furthermore, thanks to the fact that opening member16is free from any rotational connection with cap4, the angle of cap rotation before initiating the breaking of cover portion15can be adjusted, for instance to have this angle of rotation greater than the one required to break the connecting means14linking tamperproof ring12to the cap. This can be made by opportunely setting the value of play in the direction of axis A between opening member16and the receiving seat20of cap4.

Clearly, changes may be made to closure1and to the method as described and illustrated herein without, however, departing from the scope as defined in the accompanying claims.