SUBSTANCE

The present invention concerns a process for forming a pack of several containers arranged in an orderly way in one or several parallel rows, the pack being obtained by wrapping the assembly of the containers (formed of at least two containers) by a sheet obtained from a film made from a suitable plastic material, such sheet holding the containers joined to each other for storage and transportation.

Packs of the type described above are well known and widely used. They are used to pack a given number of containers including bottles (in particular for water, milk, or other drinks), cans (for beer or other drinks), jars (in particular for conserves), cardboard or paper containers (for milk, sugar, rice, pasta, and all of those products for which this type of containers can be used) .

Such containers are first put side to side in an orderly way to form one or several parallel rows, the assembly thus obtained being subsequently wrapped by a sheet obtained from a film made from a heat-sealable and usually also heat- shrinkable, plastic material (in particular different types of polyethylene are used) , in the form of a rolled-up continuous strip having an appropriate width. Two opposed edges of the sheet are made overlap (usually below the containers to be wrapped) and then hot-sealed so as to obtain a pack which has an approximately parallelepiped shape.

The pack can be provided with a handle which, in the typical case of 1.5 or 2 liters bottles for water or other types of drinks, consists of a more robust strip made from a plastic material, with a width of 2-3 cm, whose two end parts are secured, by means of an appropriate machine, to the pack (more precisely to the envelope of the pack) over a length which normally ranges from 5 to 30 cm per side.

In the last years manufacturers tend to reduce the thickness of the film from which said sheets are obtained, with the purpose of reducing the manufacturing costs and of reducing the impact on the environment resulting from the reduced quantity of plastic material (hence of oil) necessary to produce the film.

However, this trend shall reckon with the drawbacks that are encountered upon reducing the thickness of the film.

As a matter of fact, a smaller thickness of the film also reduces its performances, with a consequent smaller "strength" of the pack. By "strength" we mean the ability to hold the containers of a pack joined to each other without the envelope breaking, but also without the containers moving with respect to the packing envelope, such movement being due to a slip of the containers with respect to the respective surface of the envelope.

In order to prevent this drawback resulting from the reduced thickness of the film used, an attempt was made to use a polyethylene featuring a higher resistance to tensile stresses .

Anyway, there are insuperable limits to thickness reduction, however high resistance films are used. For example, in the case of the packing of water bottles, it has been possible to ascertain that if a thickness of 30 microns is used instead of a thickness of 45 microns, even if a high performance polyethylene is used, it might occur that, when the final user carries a single pack from the point of sales to home, the "strength" of the pack fails, with a possible leakage of bottles, besides the possibility that the handle detaches because of the envelope having torn. Take into account that a handle transfers the weight of the pack onto its two end sections secured to the envelope of the pack, end sections which have each an extension normally ranging from 10 to 40 cm , hence, because of the reduced thickness of the film, it might occur (specially in the case of packs of six 1.5 or 2 liter bottles) that the handle detaches from the envelope, with consequences that can be easily imagined (lawsuits for damages are in progress promoted by consumers) .

To solve such drawbacks, document WO2011/024050 describes an apparatus for packing an assembly of liquid container elements, for instance bottles, which implements the packing of such container elements by using a non heat- shrinkable polyethylene film, to which polymers are added suitable for increasing the mechanical resistance of the film, with a thickness not exceeding 10 microns, said film being wrapped several times around the assembly of container elements so as to reach an overall thickness suitable for supporting the loads.

However, such solution does not solve further drawbacks related to the reduced thickness of the sheet used for packing and consisting in that, when the packs shall be carried from the packing site (which, in the case of water bottles, is usually close to the sources, which are often located in mountainous areas) to the place of storage or sales, pallets are used on which the packs are orderly arranged in several superimposed layers, nothing but a thin cardboard sheet being interposed between one layer and the other. If the thickness of the sheet used for packing is smaller than 45 microns, it can occur (particularly while handling the respective pallets on roads, especially if these are steep) that the individual containers in every pack move inside the envelope. This in turn affects the stability of the assembly of the packs carried by the pallet, and specifically such assembly might disassemble, and in some cases they might even cause an overturning of the means of transportation because of the displacement of the carried weight . An object of the present invention is to provide a process for forming a pack of several containers arranged in an orderly way, in one or several rows, such process being such as not to jeopardize the "strength" of each individual pack .

Another object consists of providing a process of the type specified above that allows to produce such packs with a handle as not to present the drawback of the handle detaching therefrom because of the envelope having torn.

A further object consists of providing a process of said type that allows to produce packs that, when handled by means of a means of transportation, by using loading units, for instance pallets or footboards, its respective load does not originate an instability.

The objects specified above are achieved and their respective technical problems solved thanks to a process according to the attached claims.

The invention will be more easily understandable from the following description of an explanatory embodiment thereof, in the description of which reference will be made, for explanatory purposes only, to the process for forming packs of bottles made from a plastic material containing water or other drinks, in particular 1.5 or 2 liter bottles, to obtain a pack of six of such bottles arranged in two juxtaposed rows of three bottles each.

As already mentioned before, this pack is obtained by wrapping the assembly of the six bottles, arranged in two juxtaposed rows of three bottles each, by a sheet made from a heat-sealable plastic material, at least two of the opposed edges of the sheet being superimposed and then heat-sealed to each other in a conventional manner to obtain the desired pack, which features a substantially parallelepiped shape.

The process according to the present invention specifies that, before wrapping said sheet around the assembly of the six bottles to obtain a pack, at least a part of the surface areas of the sheet destined to get in contact with the bottles, be at least partially coated with an anti-slip substance, which prevents each of said bottles from moving with respect to the envelope of the pack.

It follows that all bottles of the pack are firmly held one against the other, without any possibility for movements or slips with respect to the envelope, thus assuring the "strength" of the pack.

This allows, even though sheets of a reduced thickness (for instance 30 microns) are used, to obtain all the same the desired "strength" of the pack, in which the individual bottles cannot move with respect to each other inside the pack and with respect to the envelope. Consequently, also the assembly of the packs carried by a pallet is more stable when handled by means of means of transportation.

The sheet might even be formed of several films having different characteristics, in particular two films coupled with each other.

According to the above considerations, it is not excluded that the complete surface of the sheet used for packing and destined to get in contact with the bottles be coated with said anti-slip substance, even though, in this case, only those parts which get in contact with the bottles (possibly including their cap) can perform an anti-slip function. In any case, every bottle shall get in contact with an area of the sheet, coated with such substance, having a sufficient extension to prevent the bottle from slipping with respect to the envelope.

It might even be convenient to coat with such substance the complete surface of the sheet, which will be facing the bottles or in any case areas thereof featuring a width greater than that strictly necessary.

The anti-slip substance might even be applied in the respective areas in a discontinuous manner, for instance in stripes, which might even cross to each other according to a "mesh" pattern, with square, rectangular, rhomboidal meshes or meshes of any other geometrical shapes.

If one wishes that the pack thus obtained be also provided with a handle in the form of a strip, whose two end sections shall be secured to the envelope of the pack, the positions where these end sections are secured to the envelope, externally thereto, shall correspond to areas of the inner surface of the envelope where the anti-slip substance is present and are also in contact with a respective bottle.

It has been possible to ascertain that, thanks to the process according to the present invention, a detachment of the handle because of the envelope having torn is avoided, because the anti-slip substance makes it possible to transfer, by friction or by adhesion, a part of the loading acting onto the handle directly to the corresponding bottles, provided the securing end sections of the handle secured in turn to the envelope have a sufficient extension indeed, and likewise a sufficient extension shall have the area of the envelope underneath, which is in contact with its respective bottle, treated with the anti-slip substance.

In the explanatory case of a pack of six 1.5 or 2 liter bottles, containing water or other drinks, wrapped by a polyethylene sheet, whose thickness can be now smaller than 45 microns, for instance 30 microns, the anti-slip substance that allows to get the results as indicated above is for instance that denominated FTR 970150231, sold by SUN CHEMICAL GROUP S.p.A. of Sordio (Lodi, Italy), a substance that has been demonstrated to be also usable in the case that the containers are cans or cardboard or paper boxes and is activated upon heating, in particular upon the heating performed to make the polyethylene sheet used for the packing heat-shrink .

It is to be pointed out that a true glue might even be used as an anti-slip substance, preferably a glue of a type that allows to separate the envelope from the bottles by tear-off, so as to prevent shreds of envelope from remaining attached to the bottles. Actually some gluing effect is also provided by the above indicated substance.

It has been possible to verify that packs obtained thanks to the process according to the present invention feature an optimum "strength", and that when such packs are handled by means of means of transportation, by using loading units like pallets or footboards, the assembly of the packs loaded onto the loading units feature a good stability, and in addition the handle does not detach when a user manually carries the pack.

However, it has been found that, in order to further improve the stability of such assemblies, the process according to the present invention can conveniently comprise an additional step consisting of at least partially coating with an anti-slip substance at least a part of those surface areas of the sheet, used to form the pack, which are destined to get in contact with the remaining packs that form the assembly loaded onto a loading unit. In practice, the envelope of a pack features inner and outer surface areas, or even its whole inner and/or outer surface, coated with an anti-slip substance, possibly applied in a discontinuous manner (for instance according to a "mesh" pattern) .

It has been found that the packs obtained in this way, when arranged orderly on a loading unit to form an assembly ready for being handled, originate assemblies which are fully stable even when the means of transportation shall face up to very steep roads and even when no thin-cardboard sheet as mentioned above is placed between the individual layers of packs that form the assembly.