Wetting unit and forming machine and method for producing unit dose articles

A wetting unit for wetting a surface of one of a first and a second continuous water-soluble films to be coupled and sealingly joined to each other so as to delimit therebetween recesses containing dosed quantities of at least one fluid composition for producing unit dose articles. The wetting unit is configured to wet only surface areas of one of the first and second continuous water-soluble films which are to be joined to the other of the first and second continuous water-soluble films.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to European Patent Application No. 21212311.1 filed Dec. 3, 2021. The disclosure of the above application is incorporated herein by reference in its entirety.

FIELD OF INVENTION

The present invention relates to a wetting unit, to a forming machine equipped with such a wetting unit, and to a forming method for producing unit dose articles.

More particularly the invention is directed to the production of unit dose pods or pouches including two water-soluble films sealingly enclosing therebetween household care compositions, such as laundry detergents, dishwasher detergents, softeners, and other compositions used in household appliances.

In the following description reference will be made to this specific field without however losing generality.

BACKGROUND AND PRIOR ART

Laundry and dishwasher detergent pods, such as generally known for instance from US2017/2982186A1, are water-soluble pouches containing highly concentrated laundry detergents, softeners, and other laundry products. Detergent pods are becoming increasingly popular in view of the ease of use for the user and the positive impact on sustainability as they are a way to reduce wasted use of powdered and liquid detergent by having precise measurements for a load.

Detergent pods are generally produced, as disclosed for instance in US2015/336692A1 and WO2015179584-A1, by forming recesses in a first water-soluble film (“bottom film”), filling the recesses with fluid compositions, applying a second water-soluble film (“top film”) over the first water-soluble film, and joining the first and second water-soluble films to each other so as to sealingly enclose the compositions between the two water-soluble films.

Joining between the two water-soluble films is performed by watering the surface of one water soluble film, prior to coupling it with the other water-soluble film after supplying the composition into the recesses of the first water-soluble film. The wetted water-soluble film is thus applied and contacted over the other water-soluble film and sealed thereto.

According to the prior art the water-soluble film which is wetted is typically the second one, i.e. the “top” film, and watering thereof is carried out in three different modes.

In a first mode, disclosed for instance in EP1641865A1, a mist of an atomized aqueous composition is applied onto the surface of the water-soluble film by a number of spraying nozzles.

In a second mode a sponge roller rotatably contacting the water-soluble film during advancement thereof supplies the aqueous composition continuously fed to its interior by means of a rotary manifold connected to the roller axis.

According to a third mode a rotating felt roller tapping into an aqueous composition basin is tangentially contacting the water-soluble film during advancement thereof.

In all above three known modes the aqueous composition is applied onto the entire surface of the second water-soluble film even if coupling thereof with the first water-soluble film would require than only a few areas thereof, namely perimetral areas, to be watered. This may cause some degradation of the two water-soluble films, whose material (typically PVA) is highly influenced by moisture, at the areas thereof which are not coupled and welded to each other.

Moreover, in all three known modes a precisely controlled traction drawing of the second water-soluble film during advancement thereof is required in order to avoid generation of creases which may prevent a uniform application of the water layer.

Additionally the second known mode is also constructively complicated owing to the provision of the rotary manifold.

OBJECT AND SUMMARY OF THE INVENTION

The object of the present invention is to overcome one or more of the problems of the prior art.

According to the present invention, this object is achieved by a forming machine for producing unit dose articles as set forth in claim1and in the subclaims depending thereupon.

According to another aspect, the present invention is directed to a method for producing unit dose.

According to a further aspect, the present invention relates to a wetting unit to be employed in the machine and in the method for producing unit dose articles.

The claims form an integral part of the technical disclosure provided here in relation to the invention.

It should be appreciated that the attached drawings are schematic and various figures may not be represented in the same scale. Also, in various figures some elements may not be shown to better show other elements.

DETAILED DESCRIPTION

FIG.1is a schematic side view of part of a machine for producing unit dose articles according to the prior art disclosed in the above, consisting of a forming unit generally indicated as10and comprising a forming surface12having a plurality of rows of cavities14and continuously movable in a machine direction MD. The forming surface12of the forming unit10in this case is the outer cylindrical surface of a drum16rotating about a horizontal axis A. In a different embodiment the forming surface12may be the outer surface of a closed-loop belt having a horizontal upper section and a lower return section.

FIG.2diagrammatically depicts one example of the pattern of one row of shaped recesses14of the forming surface12.

The forming unit10comprises a first feeding assembly comprising a first reel19(FIG.1) configured for feeding a first (top) continuous water-soluble film20at a first position24on the forming surface12. The first continuous water-soluble film20is retained on the forming surface12and is deformed into the cavities14of the forming surface12as it moves in the machine direction MD, so as to form corresponding recesses. The deformation of the first continuous water-soluble film20into the cavities14can be provided by a suction system.

A second feeding assembly including a second reel29(FIG.1) is configured for feeding a second (bottom) continuous water-soluble film30on the forming surface12at a second position32located downstream of the first position24with respect to the machine direction MD.

The unit10comprises a dosing apparatus36located above the forming surface12, in a position intermediate between the first position24and the second position32, configured for dispensing dosed quantities of at least one fluid composition into the recesses of the first continuous water-soluble film20which are set within the cavities14of the forming surface12.

The dosing apparatus36typically includes one or more dosing units each comprising a movable support body42carrying a plurality of nozzles44connected to a fluid delivery system via respective flexible tubes and having respective fluid delivery apertures facing downwardly.

After the recesses of the first continuous water-soluble film20have been filled with the fluid compositions by the dosing apparatus36, the second continuous water-soluble film30is applied at the second position32onto the first continuous water-soluble film20by a coupling roller40at the second position32, so as to form an assembled web W enclosing the dosed quantities of fluid compositions contained within the recesses between the first and second continuous water-soluble films20,30. The assembled web W is then deviated outwardly from the forming surface12by the coupling roller40.

In order to sealingly couple the first and second continuous water-soluble films20,30to each other, the forming unit10comprises a wetting unit configured for wetting the surface of the second continuous water-soluble film30upstream of the second position32. The known wetting unit comprises a wetting roller38which is in contact with the entire surface of the second continuous water-soluble film30.

In a different known arrangement the wetting unit comprises a number of nozzles spraying a mist of an atomized aqueous composition onto the whole surface of the second water-soluble film30.

The first and second continuous water-soluble films20,30are then water-sealed to each other at respective contact areas surrounding the recesses containing the dosed fluid compositions.

As already explained in the above, this known arrangement has several drawbacks which are overcome by the invention as disclosed herebelow in connection toFIGS.3-6, in which parts identical or similar to those already disclosed with reference toFIG.1are indicated by the same numerals.

In general terms the wetting unit of the forming machine according to the invention is configured to wet only the surface areas of one of the first or second continuous water-soluble films20,30which shall be sealed to the other, thus excluding at least the recesses formed by the cavities14.

Accordingly, the wetting unit of the invention as shown inFIGS.3to6is configured to wet only surface areas of the first continuous water-soluble films20which are to be put into contact and joined to the second continuous water-soluble films30.

The wetting unit ofFIGS.3-6consists of a sponge46soaked with an aqueous composition delivered by a supply dosing system, not shown in detail since within the skill of the practitioner, and touching on the first water-soluble film20upstream of the coupling roller40with respect to the machine direction MD.

As shown in better detail inFIGS.4and5the sponge46is carried by the support body42of the dosing unit36located transversely above the forming surface12of the roller16and is passed through by the nozzles44, whose fluid delivery apertures are substantially flush with the surface of the sponge46facing the forming surface12.

The sponge46is tangent to the forming surface12and is thus contacting only the perimetral areas of the surface of the first water-soluble film20which are enclosing the recesses thereof set within the cavities14.

The main advantages of the invention as disclosed in the above over the prior art reside in the following:since watering is not applied at areas of the first water-soluble film20which are not designed to be coupled with the second water-soluble film30, namely not to the recesses corresponding to the cavities14, degradation of those areas is effectively prevented and a final product (pod) of better quality can thus be obtained;no rotary manifold is required to supply the aqueous composition to the wetting unit;since wetting is performed simultaneously with filling the recesses of the first water-soluble film with the fluid compositions operated by the dosing apparatus, the physical distance and the time gap between watering and mutual coupling between the two water-soluble films is shortened, whereby the risk of generating non properly wet or even dry zones is appreciably reduced;since wetting is performed while the first water-soluble film is adhering to the forming surface of the roller by suction, any plies or non-uniformities of the first water-soluble film are drastically reduced or even eliminated thus improving the application of an homogeneous water veil on the planar surface of the water-soluble film;supplying and dosing the aqueous solution to the sponge is easier and can be carried out almost instantaneous by providing a feedback system.

FIGS.7and8, wherein parts identical or similar to those already disclosed with reference toFIG.3are indicated by the same numerals, are depicting two alternative embodiments of the invention according to which the sponge46is replaced by a wet roller. Also in both variants the arrangement is such that only the surface areas of the continuous water-soluble films20,30which are to be mutually coupled are being watered.

In the embodiment ofFIG.7a wet roller52is contacting on the second water-soluble film30upstream of the second position32, as in the prior art ofFIG.1. Its outer surface is shaped same as that of the forming surface12of the forming unit10previously disclosed with reference toFIG.2. Namely, in order to contact only the areas of the surface of the second water-soluble film30designed to be coupled to and joined with the first water-soluble film20, as diagrammatically shown in the detail on the right upper side ofFIG.7, only perimetral zones48of the roller52enclosing recesses50thereof complementary to the cavities14of the forming surface12touching on the surface of the second water-soluble film30. In this case the advancement of the second water-soluble film30has to be synchronized with the advancement of the first water-soluble film20on the forming surface12.

In the variant ofFIG.8a wet roller54is contacting on the surface of the first water-soluble film20over the forming surface12upstream of the dosing apparatus36, with reference to the machine direction MD. Watering performed by the wet roller54is thus applied onto the areas of the first water-soluble film20which are not designed to be coupled with and joined to the second water-soluble film30, namely not to the recesses thereof corresponding to the cavities14of the forming surface12.

Of course, without prejudice to the principle of the invention, the details of construction and the embodiments can be widely varied with respect to those described and illustrated, without thereby departing from the scope of the invention as defined by the claims that follow.