MACH IN E AN D METHOD FOR IMPERMEABLE COUPLING

Technical field

This invention relates to a machine for making an impermeable coupling for food use, and the relative production method.

The invention is used in particular in the food sector since it is necessary to have coupled materials available, designed for the packaging and transport of fresh food or pre-cooked food, which prevent the escape of liquids such as, for example, oils and/or sauces.

Background art

As it is known, machines for making these couplings are usually applied to a paper layer, which acts as a base for the coupling, a plastic film; this film allows any type of liquid substance to be kept inside the container, formed starting from the coupling.

These machines usually have a station designed to spread a glue and then the plastic film on the surface of the paper material to be made impermeable.

The type of machine just described has several drawbacks.

Firstly, the plastic film requires a particular treatment to be coupled in an optimum manner to the paper.

This treatment cannot be performed on certain types of film, such as, for example, those of biological origin.

This forces the use of particular glues and results in lower quality and productivity. Moreover, the station of the machine which applies the plastic film is not very versatile since it is not able to change the application method depending on the type of paper material to be coated.

An additional drawback derives from the fact that in the case of machines which deposit the plastic film, a large waste of material is obtained due to the processing. Another drawback is due to the fact that the plastic layer applied to the paper layer, as well as the glues used by the machine for gluing the layers to each other, make the coupling difficult to recycle and not resistant to heat.

In this context, the technical purpose which forms the basis of the invention is to propose a machine for making an impermeable coupling for food use which is constructionally simple.

A further aim of the invention is to provide a machine for making an impermeable coupling for food use which contains plastic films and which is, therefore, better than the prior art in terms of recycling operations.

Aim of the invention

In the context of said technical purpose, the aim of the invention is to provide a machine for making a coupling which allows an impermeable coupling for food use to be made which is recyclable and heat resistant.

The invention also relates to a method for making the coupling starting from the above-mentioned machine.

Further features and advantages of the invention are more apparent in the non limiting description which follows of a preferred embodiment of a machine for making an impermeable coupling.

Brief description of the drawings

The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

- Figure 1 is a schematic side view of a machine for making an impermeable coupling according to a first embodiment of the invention, characterised by the presence of a layer of impermeable materials positioned on a single surface of the paper layer;

- Figure 1A shows an enlarged detail of figure 1;

- Figure 2 is a schematic side view of a machine for making an impermeable coupling according to a second embodiment of the invention, characterised by the presence of the layer of impermeable material on both surfaces of the paper layer; - Figure 2A shows an enlarged detail of figure 2;

- Figure 3 is a schematic side view of a machine for making an impermeable coupling according to a third embodiment of the invention.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, the numeral "M" denotes in its entirety a machine for making an impermeable coupling for food use according to the invention.

The machine "M" comprises a plurality of operating stations each having a different function in the making of the impermeable coupling "A" which is formed by at least one layer of paper material "C", which acts as a base, and at least one layer of impermeable material "S" positioned on at least one surface of the layer of paper material "C".

Advantageously, between the layer of paper material "C" and the impermeable layer "S" there is a primer film "P" designed to improve the application and/or the efficiency of the impermeable layer.

With reference to Figure 1, the machine "M" comprises an unwinding station "D" from which the paper material "C" is unwound from a reel 1.

In an embodiment not illustrated, the paper material "C" may be supplied to the machine "M" directly from the outfeed of the production line of the paper material "C".

In this case, the paper material "C", at the outfeed from its production line, enters directly into the machine "M" without the need to be rolled on reels and then unrolled.

In the case of the embodiments shown in the accompanying drawings, the paper layer "C" is unrolled from the reel 1 and progressively fed towards the next station "E" along a feed line defined by the path between the unwinding station "D" and a last station "0", described in more detail below.

The above-mentioned station "E" comprises a second applicator 2 for applying a primer "P" on the paper layer "C". When the paper layer "C", coming out of the unwinding station "D", travels along the stretch beneath the applicator 2, the latter distributes a predetermined quantity of a primer on the surface of the paper layer "C", creating a film "P".

The primer acts as a means of joining the paper material "C" and the impermeable layer "S" which will be placed subsequently by means of a respective applicator 4. In a preferred embodiment, in such a way that the paper layer "C", in combination with the primer film "P", is able to receive in an optimised manner the impermeable layer "S", there is a subsequent station "F" comprising a pre-heating unit 3.

The pre-heating device 3 pre-heats the stretch of paper material "C", on which the primer film "P" has been applied, to a temperature of between 40°C and 180°C. The temperature may vary based on different design requirements such as, for example, the type of primer.

It should be noted that the pre-heating unit 3 can perform a twofold function, that of pre-heating the stretch of paper material "C" and/or that of drying the primer

"p"

At the outfeed from the pre-heating unit 3, the paper material "C" is suitable for receiving, on at least one of its surfaces (and in particular on the primer film "P"), the layer of impermeable material "S", comprising silica and water.

In an embodiment not illustrated, the paper material "C" feeding out of the station "E" passes directly to the station "G" for applying the layer of impermeable material comprising silica, that is to say, skipping the pre-heating step.

The layer of impermeable material "S" comprising silica and water advantageously has a viscosity of less than 10,000 cps and is applied as the last outer layer of the impermeable coupling "A" thanks to a first applicator 4, located in the station "G" downstream of the pre-heating unit 3.

The layer of impermeable material "S" comprises in its initial form 40% by volume of silanes, 30% by volume of water, 20% by volume of alcohol, 10% by volume of silica (Si02). The initial shape means the structural shape before the operations necessary for the production of the coupling "A".

After the operating steps to which the coupling "A" is subjected and in particular after the first and second heating steps (using the respective ovens) the impermeable material "S" comprises 99.93% of silica (Si02) and 0.07 of Cl.

The expression "downstream" used in this description refers to the direction of feed of the coupling "A" starting from the unwinding station "D" towards the last station "0".

The first applicator 4 distributes a layer of impermeable material "S" comprising silica in such a way that the material penetrates uniformly into the paper layer "C" below it, making it totally impermeable to liquids.

According to possible embodiments, the first applicator 4 comprises a dispensing nozzle (for example, positioned downstream of a tank or a feed device), or counter rotating cylinders wherein at least one cylinder is spread with silica whilst the other performs the transport function.

In other embodiments, the first applicator 4 may be selected between industrial brushes or spatulas, sprayers, or a silica bath where the paper layer "C" is immersed in such a way as to be made impermeable.

It should be noted that the paper layer "C" may be made totally impermeable or on one side only.

At the outfeed from the first applicator 4, the impermeable coupling "A" is complete; it has a base layer formed from paper material "C", spread on at least one relative surface with a primer film "P", and a layer of impermeable material "S" comprising silica.

Downstream of the first applicator 4, the machine "M" also comprises a station H comprising a first oven 5 in which the impermeable coupling "A" stops or passes for a predetermined period of time at a first temperature of between 100°C and 160°C to promote a first drying of said silica and said water of the impermeable material (S). In this way, the primer and the impermeable material "S" comprising silica dry and penetrate in depth in each particle of the paper layer "C" avoiding not only the formation of bubbles but also avoiding a non-uniform distribution of the impermeable material "S".

The first oven 5 allows heating of the impermeable coupling "A" to a temperature of between 100°C and 160°C based on various parameters, for example, the thickness of the layer of impermeable silica to be dried and its type.

The machine "M" comprises a second oven located downstream of the first oven 5 and configured to heat the impermeable coupling "A" to a second temperature of between 150°C and 230°C to promote the stabilisation of said silica on the impermeable material "S".

This second heating step at a temperature higher than the first allows the crystallisation of the silica on the paper material "C" to be obtained, making the reciprocal coupling optimised and resistant over time.

The machine "M" also advantageously comprises, downstream of the first oven 5 and of the second oven, a cooling unit 6 and a cutting device 7 which constitute the station "I" and the station "L", respectively.

In Figure 1, the cooling unit 6 is positioned before the cutting device 7, in this way the coupling is first brought to ambient temperature to be stabilised and then cut. The stabilising makes it possible to obtain a coupling which remains uniform over time and, therefore, once subjected to the cutting operation does not modify the relative geometries.

By means of the cutting device 7, the impermeable coupling "A" may be cut into sheets, cut to form blanks or it may be notched and/or cut.

Depending on the operation which the cutting device 7 performs, the last station "0" of the machine "M" may have different components.

In the embodiments illustrated in the accompanying drawings, the last station "O" comprises a device which rewinds the impermeable coupling "A" around a reel 8. The reel 8 is used, for example, when the impermeable coupling "A" is subjected to cuts or incisions and stored for transport and/or further processing.

If, on the other hand, the cutting device 7 cuts the impermeable coupling "A" into sheets, they are positioned in piles, for example on shelving or racks which therefore replace the reel 8 in the "0" station.

The embodiment of the machine "M" as shown in Figure 1 is usually used when obtaining an impermeable coupling "A" having the impermeable characteristic only on one surface.

Normally, the couplings "A" are used to create sheets/tubs/containers in which the impermeable part is used to prevent the liquids present in the food to be contained from escaping; the impermeable part is therefore, in these cases, in direct contact with the food.

The two further embodiments illustrated in Figures 2 and 3 show, on the other hand, two configurations of the machine "M" wherein the layer of impermeable material "S" comprising silica and water is deposited on both sides of the paper material "C".

The impermeability on both sides is usually used for making couplings designed, for example, for the production of shopping bags wherein there is the need to have both the inner surface and the outer surface perfectly impermeable.

The impermeability of both the surfaces of the coupling "A" makes it possible to obtain a two-way barrier, both from and towards the inside and/or the outside. The embodiment illustrated in Figure 2 shows a station "E" for applying the primer "P" comprising a pair of first applicators 2, 2' and a station "G" for distributing the silica comprising a pair of second applicators 4, 4'.

Each of the two above-mentioned stations "E" and "G" sees the applicators facing the two opposite sides of the paper layer "C", in such a way as to simultaneously create on both sides of the paper layer "C", a primer film "P" and a respective impermeable layer "S". In this configuration the machine "M" has the remaining stations configured as in the embodiment shown in Figure 1.

The embodiment illustrated in Figure 3, on the other hand, shows a configuration in which the stations are repeated according to the feed line of the paper layer "C". More specifically, at the end of the first series of stations "D", "E", "F", "G", "FI" the paper layer "C" is impermeable on one side.

Made impermeable in this way, it returns in a direction "N", into a second series of stations "E", "F"', "G'", "FT' with the surface to be made impermeable directed upwards.

The second set of stations may follow a curvature of the coupling, for example to overturn the coupling, exposing upwards the surface not yet made impermeable.

In a further embodiment, and shown in Figure 3, the first series of stations comprises, as the last station, the station "I" for cooling and the second series also comprises the station "I".

At the end of the second series of stations, there is also a single cutting device 7 in the "L" station and, if necessary, a reel 8 for the winding.

In other embodiments not illustrated, the stations "I" and T" and/or "L" and/or the stations "F" and "F'" might not be present.

A method is described below for making an impermeable coupling "A" using a machine "M" which comprises the steps of:

- progressively unwinding a paper material "C" starting from a feed reel 1 in such a way that the paper material "C" feeding towards the subsequent stations of the machine "M";

- distributing a layer of impermeable material "S" comprising silica and water, on the paper material "C".

This application may be performed in various ways, for example by means of counter-rotating rollers, spraying, spreading in the case of liquefied or partly liquefied silica or by immersion if the paper layer "C" is to be made permeable even laterally; - heating the impermeable coupling "A" to a first temperature of between 100°C and 160°C inside a first oven 5 to promote a first drying of the silica and of the water of the impermeable material "S",

- heating the impermeable coupling A to a second temperature of between 150°C and 230°C to promote the stabilisation of the silica on the impermeable material

"S".

The method also advantageously comprises the step of placing a primer film "P" on the surface of the paper material "C" using a second applicator 2.

The method also comprises further steps which refer, respectively, to the pre- heating unit 3, the cooling unit 6 and the cutting device 7, in particular:

- pre-heating, downstream of the second applicator 2, the paper layer "C" coupled with the primer film "P", in such a way as to bring the paper layer "C" to a temperature of between 40°C and 180°C;

- cooling the impermeable coupling "A", after the heating operation, in such a way as to stabilise the coupling "A" for the subsequent processing;

- cutting the impermeable coupling "A", after heating, using a cutting device 7 to form sheets, blanks or notches.

In a preferred embodiment of the method, the cooling step precedes the cutting step.

In a possible further embodiment of the method, on the other hand, the steps relating to pre-heating, cooling and cutting are not present.

The invention achieves the above-mentioned aims, eliminating the drawbacks of the prior art.

In effect, the machine and the method as described and claimed allow a precise creation of an impermeable, recyclable and heat resistant coupled material designed to be used in the food industry.

Moreover, the machine is constructionally simple and versatile and adaptable in the methods for applying the impermeable silica layer. The presence of the impermeable layer "S" comprising silica, instead of the layer of plastic material used in the prior art, makes it possible to optimise any operation for recycling the coupling "A" according to the invention.

Moreover, the use of silica allows a biodegradable and transparent coupling A to be obtained.

Moreover, by varying the percentage of silica of the layer of impermeable material "S" relative to the paper material "C" it is possible to vary the barrier effect for liquids and resistance to heat, thereby obtaining a greater resistance over time of the foods contained in the food coupling "A" according to the invention.