A communicating duct for containers , and a container provided with such a duct

Technical Field

The present invention relates to a communicating duct for containers used typically in the packaging of cohesionless or free-flowing products , also to a container furnished with such a duct . The invention is applicable to any given container for free-flowing food products , and in particular for liquid products such as milk, fruit juices , yoghurt , mineral water and the like .

Background Art

The prior art embraces containers consisting in a recipient fashioned from a flat blank of multi-layer material folded in such a way as to assume a shape suitable for holding a liquid product . Also forming part of the container is a communicating duct made of rigid material , associated with the recipient by way of a portion serving as the outlet of the recipient . The duct presents a tubular element such as can be coupled with a closure cap , and a connecting portion that will be bonded ultimately to the outlet portion of the recipient . With this end in view, the flat blank is coated on one of its two faces with a film

of heat-sealable material , generally polyethylene , located on the inside of the recipient when formed and positioned to coincide with the outlet portion . The heat-sealable film serves to unite the recipient and the connecting portion of the communicating duct , hermetically, by incorporation into a weld .

To obtain a properly made and reliable weld, the communicating duct of a typical prior art container is fashioned entirely from low density polyethylene . When heated, in effect , low density polyethylene will adapt easily to the shape and imperfections of the multi-layer material and thus ensure a tight seal at the interface, impermeable to liquids and gases .

Conversely, it has been found that a duct made entirely of low density polyethylene cannot withstand the loads to which it is subj ected during production and bottling . In practice , the weld between the duct and the recipient is effected generally by means of sonotrodes applied to the multi-layer material of the outlet portion, which in turn is offered to an outer surface presented by the connecting portion of the duct . The pressure applied through the sonotrodes is counteracted by anvil elements , each placed against a relative inner surface of the connecting portion . Disadvantageously, heat is generated by the action of the sonotrodes in the outer surface of the connecting portion associated with the multi-layer material , with the result that the selfsame connecting portion, being made entirely of low density polyethylene, is rendered malleable to a degree throughout and thus

caused to deform by the combined action of the sonotrodes and the anvil elements .

During the bottling step, furthermore , liquids are subj ected generally to pasteurization processes and batched into the containers while still hot , with the result that the temperature of the connecting portion will also be raised by the heat transmitted directly from the liquids passing through the duct , and by the heat transmitted via conduction through the container when filled with the product . In the step subsequent to the filling step, the heated duct deforms when subj ected to the tightening torque of the cap screwed onto the tubular element .

Finally, the low density polyethylene utilized for the duct is permeable to gases , so that when bottling beverages , any gases added to the liquids may escape to the surrounding environment , whilst air can also penetrate from outside and cause the contents to be contaminated . The obj ect of the present invention is to overcome the problems described above through the adoption of a communicating duct for containers that can both guarantee an optimum bond with the recipient to which it is j oined, while holding its original shape during production and filling operations , and when in use ultimately.

A further obj ect of the invention is to provide a container that will ensure a fluid-tight seal and impermeability to gases .

Disclosure of the Invention

The stated obj ects are realized in a communicating duct for containers embodied according to the present invention. The duct is composed of a tubular element and a connecting portion combining to establish at least one flow passage between a container and the surrounding environment , the connecting portion being embodied integrally with the tubular element and presenting at least one mating surface sealable hermetically to an outlet portion of the container; to advantage , the mating surface consists of low density polyethylene , whilst the body of the duct is fashioned from at least one material stronger than low density polyethylene .

The stated obj ects are realized similarly in a container composed of a base portion, an outlet portion associated and combining with the base portion to create at least one cavity such as will hold a product , and at least one communicating duct attached to the outlet portion. The outlet portion of the container presents at least one mating surface weldable to the communicating duct , and the duct itself will incorporate the features as recited in one or more of the appended claims 1 to 24.

The invention will now be described in detail , by way of example , with the aid of the accompanying drawings , in which :

-figure 1 is a perspective view of a communicating duct for containers in accordance with the present invention, seen associated with a container;

-figure 2 is a longitudinal section showing a first embodiment of the communicating duct of figure 1 ; -figure 3a is a longitudinal section showing a second embodiment of the communicating duct of figure 1 ; -figure 3b is a longitudinal section showing a third embodiment of the communicating duct of figure 1.

With reference to the drawings , numeral 1 denotes a communicating duct for containers , in its entirety, embodied according to the present invention . . The communicating duct 1 is attachable to a recipient 2 of conventional type , shown fragmentarily in the drawings , which will be fashioned from a sheet of multi-layer material . The recipient 2 and the duct 1 combine to form a container 3 such as can be filled with a cohesionless and preferably liquid food product , typically milk, water, fruit juice or the like . The recipient 2 comprises a base portion 4 , part of which can be seen in figure 1 , and an outlet portion 5 attached to the base portion 4 in such a way as to create at least one cavity in which the food product is held . The outlet portion 5 presents at least one mating surface 5a that is heat-welded to the communicating duct 1 so as to establish a seal guaranteed fluid-tight in respect of the liquid contents , and impermeable to gases (see figures 2 , 3a and 3b) . To this end, the recipient 2 is fashioned from a sheet of multi-layer material of which one face is coated with a film of heat-sealable material , ideally polyethylene , positioned to face inwards at the mating surface 5a when the recipient is formed .

The communicating duct 1 presents a tubular element 6 and a connecting portion 7 , aligned on a longitudinal axis denoted X and combining to delimit an internal passage 8 between the container 3 and the surrounding environment . The tubular element 6 terminates in a neck 9 , preferably affording an external thread 10 to accept a closure cap of conventional embodiment , not illustrated in the drawings . The connecting portion 7 is integral with the tubular element 6 and presents at least one mating surface 11 that will be bonded hermetically to the mating surface 5a presented by the outlet portion 5 of the container 3.

In the preferred embodiments described and illustrated, the tubular element 6 is a cylinder of circular section, whilst the connecting portion 7 is frustopyramidal externally, with a square base . The connecting portion 7 therefore presents four mating surfaces 11 , each associated with one of the mating surfaces 5a presented by the outlet portion 5 of the container 3 , which likewise appears frustopyramidal in shape with a square base .

Moreover, in accordance with a further embodiment not shown in the accompanying drawings but described and illustrated in patent application WO 03/059762 , incorporated here by reference , the connecting portion 7 is provided with four tags , each extending radially from one of the four corner edges along which the mating surfaces 11 are j oined . Each such tag is interposed between two corresponding edges afforded by folds made in the multi-layer material at

the outlet portion 5 of the container 3.

In other alternative embodiments , not illustrated, the connecting portion 7 might assume different shapes , frustoconical for example , such as will allow its adaptation to a recipient of whatever preferred geometry.

Advantageously, and unlike ducts identifiable with the prior art , the communicating duct 1 disclosed is composed of at least two materials , one such material being low density polyethylene (LDPE) , which is used for the mating surface 11 destined to interface hermetically with the mating surface 5a presented by the outlet portion 5 of the container 3. Low density polyethylene , generally considered, is polyethylene having a density preferably less than 0.930 g/cm ³ . In the event of the duct 1 being furnished with the aforementioned tags , these too will be preferably of LDPE .

Likewise advantageously, the communicating duct 1 proper is fashioned from a material stronger than low density polyethylene . A stronger material signifies a material of which the hardness , ultimate stress and deformability properties are superior to those of LDPE . Preferably, the material selected as having greater strength will be medium density and/or high density polyethylene (MDPE, HDPE) , which are better able to withstand the loads imposed during manufacture and subsequent use of the containers even at temperatures of up to 80 -100 ⁰ C .

Medium density polyethylene is regarded generally as polyethylene having a density between 0.930 g/cm ³ and 0.940 g/cm ³ . High density polyethylene is regarded generally as polyethylene having a density greater than 0.940 g/cm ³ .

In a preferred embodiment , finally, the duct 1 will comprise a layer 12 of material impermeable to gases , surrounding the flow passage 8 , such as will prevent both the leakage of gases added to a liquid contained in the recipient 3 , and/or the infiltration of air from the surrounding environment .

In the first embodiment of the duct 1 , shown in figure 2 , the tubular element 6 is fashioned entirely of high or medium density polyethylene , whilst the connecting portion 7 is fashioned entirely of low density polyethylene . In addition, the layer 12 of gas-impermeable material is located internally of the duct 1 , applied to an inside face of the selfsame duct and delimiting the flow passage 8. In both of the embodiments shown in figures 3a and 3b, both the tubular element 6 and the connecting portion 7 are made in part of high or medium density polyethylene . In particular, the tubular element 6 and the connecting portion 7 both of the second embodiment (figure 3a) and of the third embodiment

(figure 3b) each comprise a respective radially outer portion 13a and 13b and a respective radially inner portion 14a and 14b . The flow passage 8 is delimited by the radially inner portions 14a and 14b . In these embodiments , the layer 12 of gas-impermeable material

is interposed between the radially inner portion 14a and 14b and the radially outer portion 13a and 13b of the tubular element 6 and the connecting portion 7.

In the example of figure 3a, both the radially inner portion 14a and the radially outer portion 13a of the tubular element 6 are made of high or medium density polyethylene . Also, both the radially inner portion 14b and the radially outer portion 13b of the connecting portion 7 are made of low density polyethylene .

In the example of figure 3b, the radially inner portion 14a of the tubular element 6 and the radially inner portion 14b of the connecting portion 7 are made of high or medium density polyethylene . Also, both the radially outer portion 13a of the tubular element 6 and the radially outer portion 13b of the connecting portion 7 are made of low density polyethylene .

Whilst the drawings illustrate only certain possible combinations of materials , the scope of the present invention extends nonetheless to cover other alternative solutions , such as utilizing low density polyethylene , for example , for the radially inner portion 14a of the tubular element 6 , always provided that LDPE is used for the mating surface 11 welded hermetically to the corresponding mating surface 5a presented by the outlet portion 5 of the container 3 , and that the duct 1 , and in particular the tubular element 6 , contains a material stronger than low density polyethylene .

Also, the layer 12 of gas-impermeable material can be located to coincide only with the areas consisting exclusively in LDPE, hence permeable to gases by their very nature . Preferably, the LDPE material utilized will have a density of between 0.920 g/cm ³ and 0.925 g/cm ³ and a melt index of between 2 g/min and 10 g/lθ min.

Again preferably, the HDPE material utilized will have a density of between 0.950 g/cm ³ and 0.965 g/cm ³ and a melt index of between 2 g/min and 10 g/10 min .

Finally, and likewise preferably, the MDPE material utilized will have a density of between 0.935 g/cm ³ and 0.940 g/cm ³ and a melt index of between 2 g/min and 10 g/10 min . The obj ects stated at the outset are achieved by the present invention, and the problems associated with the prior art duly overcome .

In effect , a duct embodied in accordance with the present invention can be heat-welded faultlessly to the respective recipient and will at the same time guarantee a structural strength sufficient to prevent its deformation during the various steps of assembly, filling and use , even when raised to temperatures well above ambient , typically < 80 - 100 ⁰ C . Moreover, when the container is closed with a cap, the duct according to the invention will ensure that gaseous substances can neither leak from the cavity of the container to the surrounding environment nor infiltrate in the opposite direction, guaranteeing as a result that the properties of the beverage held in

the container remain intact , and that the beverage itself will not be contaminated .

Finally, it will be seen that when the container 3 is to contain fizzy beverages , or beverages highly sensitive if exposed to the surrounding environment , that is to say especially perishable , such as milk, fruit juices without preservatives and other such products , which require a container of multi-layer material comprising a layer or metal foil , the communicating duct can be fashioned advantageously with polyethylene of low density, high density or medium density, to equally good effect .

In this instance the communicating duct will be furnished with a layer 12 of gas-impermeable material surrounding the flow passage .