WO2011077375A2

WO2011077375A2 - Labelling machine

Info

Publication number: WO2011077375A2
Application number: PCT/IB2010/055986
Authority: WO
Inventors: Andrea Zucchini
Original assignee: T-Trade Engineering S.R.L.
Priority date: 2009-12-24
Filing date: 2010-12-21
Publication date: 2011-06-30
Also published as: ITBO20090828A1; IT1396874B1; WO2011077375A3

Abstract

A labelling machine comprises first feed means (3, 14, 25) designed to advance an adhesive-coated web (2) along a first feed path (Pl); second feed means (11, 12) designed to advance a print ribbon (8) along a second feed path (P2) having at least one stretch (S) superposed over the first feed path (Pl); and a print head (7) operating on the print ribbon (8) in such a way as to thermally transfer ink from the print ribbon (8) to the adhesive-coated web (2). The superposed stretch (S) extends downstream of the print head (7) for a length (T) greater than or equal to 12 millimetres to allow use of blowing means (20) for cooling the web and ribbon (2, 8) in transit along the superposed stretch (S) of the paths (P1, P2).

Description

Labelling machine Technical Field

This invention relates to a labelling machine.

More specifically, the invention relates to an automatic labelling machine of the type which uses an adhesive-coated web and which cuts the web into separate labels to be applied to containers or packs.

Background Art

Automatic labelling machines are known which comprise a silicone roller round which the adhesive-coated web is partly wound and a cutting device located downstream of the roller relative to the direction of feed of the adhesive-coated web in order to cut the web into lengths forming the labels.

A printing device also operates at the roller to press the adhesive-coated web against the silicone roller and leave on the web a caption, a shape or, more generally, a graphic design as, for example, a brand logo.

The printing device comprises a print ribbon, which is made to feed forward in the immediate vicinity of the adhesive-coated web and in the same direction as the latter, and a print head operating at the roller to transfer a predetermined quantity of ink from the print ribbon to the adhesive-coated web.

The print ribbon consists of plastic film coated with a layer of ink designed to be transferred to a surface to be printed.

The ink is transferred using traditional methods based on the generation of micro electric discharges which strike the print ribbon at a dot matrix to be printed and, through localized heating, transfer dots of ink on the adhesive-coated web below. The higher the temperature created (linked to the quantity of electric current discharged) and/or the longer the time the print ribbon is held in contact with the adhesive-coated web, the greater is the quantity of ink transferred and the more effective is the transfer.

The quantity of ink transferred is also the greater the greater the pressure applied by the print head on the print ribbon.

Disadvantageously, it has been found that in the prior art machines, the aforementioned heating also has major drawbacks. First of all, a direct consequence of heating is wear on the print head. In effect, the heat tends to deteriorate the print head very rapidly and the head must be substituted frequently during the life cycle of a traditional labelling machine.

In the second place, excessive heating tends to cause the adhesive-coated web to adhere excessively to the print ribbon, especially at the points of ink transfer. Adhesion, favoured by the high level of localized heating, hinders subsequent detachment of the print ribbon (which must be rewound onto a respective waste reel) from the adhesive-coated web (which, instead, must be cut into adhesive labels ready for use).

As a result of adhering in this way, the adhesive-coated web may tend to follow the print ribbon and to be wound onto the ribbon reel, which means frequent machine shutdowns and operator intervention to disentangle the adhesive-coated web and correct its feed path.

The aforementioned excessive heating also gives rise to the serious risk of breaking the print ribbon because the heat generated by the micro electric discharges greatly weakens the ribbon.

Another penalizing factor in the aforementioned prior art machines is due to the fact that immediately downstream of the print head there is a cutting station where the adhesive-coated web is divided into ready-to-use adhesive labels. When the adhesive-coated web reaches the cutting station, it must already be separate from the print ribbon.

Besides, since the adhesive-coated web is normally fed with reciprocating feed motion (once the label has been cut off, the adhesive-coated web is fed backwards so that the front end of it next after the label cut off is brought back under the print head), in the prior art labelling machines it is specifically desirable to have the smallest possible distance between the print head and the cutting station, so that the time needed to move the web back is minimized and productivity thereby increased.

Therefore, the point where the ribbon and web are detached from each other is just after the print head (as little as approximately 3-5 mm after) and the time the web and ribbon are left in contact with each other is extremely reduced. In these machines, therefore, to allow ink to be transferred effectively, the temperature and pressure applied by the print head are increased but at the cost of reducing the working life of the print head itself and greatly weakening the print ribbon, which thus becomes subject to frequent breaks. Moreover, in the aforesaid prior art labelling machines, the path followed by the print ribbon after the print station diverges very gradually from the adhesive-coated web, necessarily on account of the inevitable dimensions of the print head (immediately after which the reel for the used print ribbon is located, which must obviously be located downstream of the print head) and this further facilitates adhesion between ribbon and web.

Disclosure of the Invention

In this context, the technical purpose which forms the basis of this invention is to propose a labelling machine which overcomes the above mentioned disadvantages of the prior art.

In particular, this invention has for an aim to provide a labelling machine which offers a high level of reliability and, more specifically, which requires little maintenance and is not subject to frequent shutdowns for servicing purposes.

The technical purpose indicated and the aim specified are substantially achieved by a labelling machine with the technical features described in one or more of the appended claims.

Brief Description of the Drawings

Further features and advantages of the present invention are more apparent from the non-limiting description which follows of a preferred, non-limiting embodiment of a labelling machine as illustrated in the accompanying drawings, in which:

- Figure 1 schematically represents a labelling machine according to this invention in a first embodiment of it;

- Figure 2 is a simplified perspective view of a part of the machine of Figure 1;

- Figure 3 schematically represents a labelling machine according to this invention in a second embodiment of it;

- Figure 4 is a simplified perspective view of a part of the machine of

Figure 3;

- Figure 5 is a detail of the part of the machine of Figure 4, viewed in cross section according to the plane labelled A- A in Figure 4. Detailed Description of the Preferred Embodiments of the Invention

In the accompanying drawings, the numeral 1 denotes in its entirety a labelling machine according to this invention.

The labelling machine 1 is of the type designed to use a continuous, adhesive-coated web 2, preferably of paper or plastic, which can be fed by unwinding a roll not illustrated.

The adhesive-coated web 2 is of the type having a smooth first side 2a which is suitable for printing with graphical designs, captions or the like, and an adhesive-coated second side 2b which is suitable for direct application on a product to be labelled.

With reference to the accompanying drawings, the adhesive-coated second side 2b is the underside of the web 2.

After being unwound from the roll, the web is made to advance along a first feed path "PI" in a direction of feed "A" in order to receive a graphic design and/or a caption and then cut into lengths, each of which forms a single label.

The labelling machine 1 comprises a supporting roller 3 which the adhesive-coated web 2 rests on or is partly wound round during its feed movement. The supporting roller 3 is rotatable about a fixed axis "X", preferably horizontal, and is preferably made entirely of, or coated with, a silicone material for reducing adhesiveness to the adhesive-coated web 2 (the adhesive side of the web 2 faces the supporting roller 3).

The supporting roller 3 has an outside surface 3 a which occupies a preferably cylindrical space. Alternatively, however, it might also occupy a space having a different shape, provided always that it is suitable for supporting the continuous web as the latter advances. The supporting roller 3 is positioned in such a way that it is tangent to the first path "PI" followed by the adhesive-coated web 2.

Figures 1 and 2 show a first embodiment of the labelling machine 1 according to this invention.

In this embodiment, formed on the outside surface 3 a of the supporting roller 3 are one or more peripheral grooves 4, annular in shape and preferably centred on the axis of rotation "X" of the supporting roller 3.

The peripheral grooves 4, which do not alter the overall space occupied by the supporting roller 3, extend preferably in a plane perpendicular to the axis of rotation "X" so that during the rotation of the supporting roller 3, the grooves are positioned according to a stationary profile.

Immediately downstream of the supporting roller 3, there are one or more diverting discs 5, each of which is partly inserted in a respective peripheral groove 4.

In this preferred embodiment of it, the labelling machine 1 comprises a plurality of diverting discs 5 and the same number of peripheral grooves 4, equally spaced from each other along the axis of rotation "X" of the supporting roller 3.

Looking in more detail, each diverting disc 5 partly penetrates into the space occupied by the supporting roller 3 in such a way as to intersect the imaginary extension of the outside surface 3 a of the supporting roller 3 at the grooves 4.

Thus, if the adhesive-coated web 2 adheres to the outside surface 3 a of the supporting roller 3, it encounters at least one of the diverting discs 5 when the supporting roller 3 rotates.

Preferably, the diverting discs 5 are rotatable about the same, common axis of rotation "Y" which is preferably parallel to the axis of rotation "X" of the supporting roller 3.

Preferably, also, the diverting discs 5 are made to rotate as one about the axis of rotation "Y", for example by being mounted on a single shaft 6 with fixed axis.

The shaft 6 is preferably driven rotationally through the use of a drive device (not illustrated), such as, for example, an electric motor, pulley or other transmission system.

The drive device can adjust the rotation speed of the diverting discs 5 as a function of the rotation speed of the supporting roller 3.

In any case, the direction of rotation of the diverting discs 5 is concordant with the direction of rotation of the supporting roller 3 so that during the rotation of the supporting roller 3, the diverting discs 5 can intercept a front portion of the adhesive-coated web 2 and move it away from the supporting roller 3 itself.

At a position facing the supporting roller 3 and upstream of the diverting discs 5 there is a print head 7 which is designed to impress a caption or graphic design on the first side 2a of the adhesive-coated web 2.

The print head 7 is of substantially known type and requires the use of a print ribbon 8 which is fed in the same feed direction as the adhesive-coated web 2 and above the latter. The print ribbon is defined by a continuous base (for example, plastic film) having one side at least partly coated with ink.

The print head 7 is designed to cause the print ribbon 8 to transfer ink to the adhesive-coated web 2 using dot-by-dot electric discharges, according to a substantially known technology. During this operation, the outside surface 3 a of the supporting roller 3 defines a contact surface which supports the portion of the adhesive-coated web 2 subjected to the print process.

The print ribbon 8 is preferably unwound from a respective first reel 9 and then wound onto a respective second reel 10.

The print ribbon 8 is guided by respective second feed means which make it advance along a second feed path "P2" with continuous or intermittent (that is to say, step-by-step) feed motion in the same direction of feed whatever the case. The second feed means comprise a feed tension roller 11 located upstream of the print head 7 for example positioned to guide the print ribbon 8 from the respective first reel 9 to the print head 7 (Figure 1).

Preferably, the second feed means further comprise a detachment blade 12 located downstream of the print head 7 and designed to facilitate detachment of the adhesive-coated web 2 and print ribbon 8 from each other. To perform this function, the detachment blade 12 has a pointed tip which is directed away from the print head 7 and round which the print ribbon 8 is trained in such manner as to divert the ribbon at an angle a preferably greater than 90 degrees, more preferably greater than 110 degrees and still more preferably, greater than 120 degrees.

Preferably, the detachment blade 12 is made of an electrically conductive material to allow the print ribbon 8 (which comprises a plastic base) to discharge static electricity that accumulates during the feed movement).

In a preferred embodiment of it, the detachment blade 12 is made of a composite material, preferably carbon fibre.

The aforesaid second feed means are made in such a way as to confer on the feed path "P2" of the print ribbon 8 a configuration having a stretch "S" which is superposed over the feed path "PI" of the adhesive-coated web 2. More specifically, the superposed stretch "S" extends immediately downstream of the print head 7 (and thus also of the supporting roller 3) and is straight.

The function of the superposed stretch "S" is that of allowing predetermined portions (selected by the print head) of the ink layer on the print ribbon 8 to be transferred to the adhesive-coated web 2 below it. In fact, along the stretch "S", the web and ribbon 2, 8 are in contact with each other. Advantageously, the aforesaid superposed stretch "S" extends downstream of the print head 7 for a length "T" greater than or equal to 12 millimetres, more preferably greater than or equal to 15 millimetres, and still more preferably, greater than or equal to 20 millimetres.

The aforesaid value for the length "T" of the superposed stretch "S" is measured between the outfeed end of the print head 7 and the pointed tip of the detachment blade 12.

These length values allow the print ribbon 8 to remain in contact with the adhesive-coated web 2 for long enough to correctly and completely transfer the ink.

Downstream of the diverting discs 5, there is a cutting station 13 of substantially known type which cuts the adhesive-coated web 2 (with the captions and/or graphic designs previously printed on it) into lengths forming the labels to be applied to the products.

The movement of the adhesive-coated web 2 occurs in the direction of the cutting station 13 between the step of printing and the step of cutting, and in the opposite direction (towards the print head 7) between the step of cutting and the next step of printing. In other words, the adhesive-coated web 2 is fed forward (preferably using suitable drive means, not illustrated, which might operate, for example, on the supporting roller 3) with reciprocating feed motion, that is to say, to and fro motion towards and away from the cutting station 13, so as to take the front end of the adhesive-coated web 2 back under the print head 7 each time the cutting station 13 cuts off the front portion of the adhesive-coated web 2 to form a label. Thus, the adhesive-coated web 2 reverses its direction twice for each step in the production of a label.

In one possible embodiment, illustrated in Figure 1, there may be a feed belt device 14 interposed between the diverting discs 5 and the cutting station 13 and designed to facilitate feeding of the adhesive-coated web 2 towards the cutting station 13.

The feed belt device 14 comprises one or more pairs of pulleys 15, 16, round each pair of which a respective belt 17 is trained.

Each belt 17 has a straight segment 18 extending between the two pulleys 15, 16, facing the adhesive-coated web 2 and forming a support for the adhesive- coated web 2 itself. Preferably, the straight segment 18 of the belt 17 lies in a plane whose extension is tangent to the respective diverting disc 5. That guarantees a uniform surface on which the adhesive-coated web 2 is fed forward from the supporting roller 3 to the cutting station 13.

Preferably, also, the straight segments 18 of the belts 17 delimit, at the superposed stretch "S" and in conjunction with the print ribbon 8, a guide channel 19 for the feeding of the adhesive-coated web 2.

More specifically, the straight segments 18 of the belts 17 and the print ribbon 8 form a pair of opposite, parallel aprons designed to facilitate feeding of the adhesive-coated web 2 after it has been printed.

During the feed movement inside the guide channel 19, not only do the belts 17 contribute to determining the feeding of the adhesive-coated web 2 but so does the print ribbon 8 which generally adheres to the adhesive-coated web 2 at the points where the ink is transferred.

According to a different embodiment, the aforesaid feed belt device 14 may be omitted.

According to a preferred embodiment, under the diverting discs 5 and/or the feed belt device 14, blower means 20 are provided for directing a jet of air towards the second side 2b (the underside) of the adhesive-coated web 2 in order to cool the latter after it has undergone the heating effect created by the print head 7. Advantageously, the jet of air created by the blower means 20 also has the effect, at the aforementioned superposed stretch "S", of keeping the adhesive-coated web 2 in contact with the print ribbon 8 above it, in such a way that the adhesive- coated web 2 is dragged forward, that is, accompanied towards the cutting station 13.

The greater the length "T" of the superposed stretch, the greater this dragging effect is.

The Applicant has found that the aforementioned values for the angle of divergence a can be obtained mainly thanks to the fact the length T" of the superposed stretch "S" is greater than or equal to 12 millimetres. In effect, when "T" has these values, it is possible for the print ribbon 8 not to interfere with the print head 7 even if the angles of divergence a are close to (or greater than) 120 degrees.

Figures 3 to 5 show a second embodiment of the labelling machine 1 according to this invention.

As shown in Figures 3-5, the supporting roller 3 has partially wound round it one or more diverting belts 21 placed side by side and having a first part which is in contact with the outside surface 3 a of the supporting roller 3 and a second part which extends away from the supporting roller 3, and more specifically, downstream of the roller 3 relative to the feed direction "A" of the adhesive- coated web 2.

The second part of each diverting belt 21 is wound around an idler member

22 which, as shown in the accompanying drawings, may be embodied by a common supporting shaft for the second parts of all the diverting belts 21. The idler member 22 is rotatable about a respective axis of rotation "W" parallel to the axis of rotation "X" of the supporting roller 3.

The idler member 22 is located downstream of the supporting roller 3 relative to the direction of feed of the adhesive-coated web 2 so that as the supporting roller 3 rotates, the adhesive-coated web 2 passes, at the supporting roller 3, from a first condition where it is at least partly supported by the outside surface 3 a of the supporting roller 3 to a second operating condition where it is entirely supported by the diverting belts 21.

The function of the diverting belts 21 is therefore that of facilitating detachment of the adhesive-coated web 2 from the outside surface 3 a of the supporting roller 3.

More specifically, at the first position, the adhesive-coated web 2 adheres to the outside surface 3 a of the supporting roller 3, covering entirely one or more of the diverting belts 5.

On reaching a predetermined angular position during the rotation of the supporting roller 3, the diverting belts 5 (which are interposed between the outside surface 3 a of the supporting roller 3 and the adhesive-coated web 2) move away from the supporting roller 3 to reach the idler member 22 and by so moving facilitate detachment of the web 2 from the supporting roller 3 overcoming any forces of adhesion between the web 2 and the roller 3.

Each of the diverting belts 5 is preferably defined by a base made from Kevlar fibre or steel (preferably in the form of a plurality of wires) externally coated with low-adhesion material such as, for example, a polyurethane or a silicone material.

The base made of steel or Kevlar guarantees high specific strength for the diverting belts 5, allowing the belts 5 to be made in a considerably reduced size. Besides, the purpose of reducing the size of the diverting belts 5 is to reduce the surface of them that is in contact with the adhesive side of the adhesive-coated web 2 in order to facilitate its subsequent detachment from the diverting belts 5.

Preferably, the silicone material the supporting roller 3 is made of has a surface hardness of between 40 and 65 Shore A, more preferably between 45 and 55 Shore A and still more preferably, equal to 50 shore A, in order to allow each diverting belt 21 to sink into the silicone material of the supporting roller 3 to a predetermined extent.

More specifically, the diverting belts 21 are tensioned in such a way that the silicone coating of the supporting roller 3 is elastically deformed at the portions of it which come into contact with the diverting belts 21.

Preferably, each diverting belt 21 is subjected to a pulling tension such that the diverting belt 21 portion which is trained around the supporting roller 3 has an outside diameter that is substantially equal to a corresponding outside diameter of the supporting roller 3 when not deformed.

To accomplish this, in accordance with a possible embodiment, tensioning means (not illustrated) are provided for operating on the diverting belts 21 in such a way as to cause the belts 21 to sink into the silicone coating of the supporting roller 3 to a predetermined extent such that the outside diameter of each of the belts 21 is equal to the outside diameter of the supporting roller 3 when it is not deformed.

In other words, the silicone material the supporting roller 3 is made of is locally flattened by each of the diverting belts 21 to an extent which is substantially equal to the thickness "s" of the belt 21 itself.

The tensioning means may be defined by a system for adjustably fastening the idler member 22 or, alternatively, may comprise one or more tensioning rollers operating on the diverting belts 21 and located on the path followed by the diverting belts 21 themselves.

According to a second embodiment, no specific tensioning means are provided and the desired sinking of the diverting belts 21 is achieved by suitably sizing the extension of each diverting belt 21 in such a way that each belt 21, once mounted, compresses the silicone coating of the supporting roller 3 and sinks into it to a desired extent defined by a value of deformation.

The deformation of the silicone coating of the supporting roller 3 by one of the diverting belts 21 is illustrated in Figure 5.

At a position facing the supporting roller 3 and upstream of the diverting belts 21 there is a print head 7 which, in the same way as described for the embodiment shown in Figures 1 and 2, is designed to impress a caption or graphic design on the first side 2a of the adhesive-coated web 2.

In this case, thanks to the fact that, as just described, the diverting belts 21 sink into the silicone material of the supporting roller 3, the surface offered to the print head 7 by the supporting roller 3 is regular, without bumps or unevenness, and therefore allows the print head 7 to perform its printing function correctly.

The print head 7 is substantially identical to the print head 7 described above.

In exactly the same way, the print ribbon 8 is identical to the print ribbon 8 described above and its feed path "PI" therefore has the same stretch "S" where it is superposed over the feed path "P2" of the adhesive-coated web 2.

The substantial difference between the embodiment illustrated in Figures 3- 5 and the one illustrated in Figures 1 and 2 lies in the fact that in the embodiment of Figures 3-5, the feed belt device (now denoted by the reference numeral 25) comprises the aforementioned diverting belts 21, which are partly wound round the supporting roller 3.

Similarly, however, each of the diverting belts 21 also has a straight segment 26 extending between the supporting roller 3 and the idler member 22, facing the adhesive-coated web 2 and forming a support for the adhesive-coated web 2.

Preferably, the straight segments 26 of the diverting belts 21 delimit, at the superposed stretch "S" of the web and ribbon 2, 8 and in conjunction with the print ribbon 8, a guide channel 27 for the feeding of the adhesive-coated web 2.

More specifically, the straight segments 26 and the print ribbon 8 form a pair of opposite, parallel aprons designed to facilitate feeding of the adhesive- coated web 2 after it has been printed.

In this case, too, during the feed movement inside the guide channel 27, not only do the diverting belts 21 contribute to determining the feeding of the adhesive-coated web 2 but so does the print ribbon 8 which generally adheres to the adhesive-coated web 2 at the points where the ink is transferred.

Advantageously, in this case too, the superposed stretch "S" of the feed paths "PI", "P2" of the web and ribbon 2, 8, extends downstream of the print head 7 for a length greater than or equal to 12 millimetres, more preferably greater than or equal to 15 millimetres, and still more preferably, greater than or equal to 20 millimetres. These length values allow the print ribbon 8 to remain in contact with the adhesive-coated web 2 for long enough to correctly and completely transfer the ink.

Advantageously, in this embodiment, too, under the diverting belts 21, blower means 20 are provided for directing a jet of air towards the second side 2b (the underside) of the adhesive-coated web 2 in order to cool the latter after it has undergone the heating effect created by the print head 7 and, for the same reasons mentioned in connection with the previously described embodiment, to allow the print ribbon 8 to drag the adhesive-coated web 2 in such a way as to facilitate the latter's feed motion.

Similarly to the embodiment described previously, downstream of the diverting belts 21, there is a cutting station 13 of substantially known type which cuts the adhesive-coated web 2 (with the captions and/or graphic designs previously printed on it) into lengths forming the labels to be applied to the products.

Advantageously, at the end of the superposed stretch "S" of the two paths "PI", "P2", the second path "P2" followed by the print ribbon 8 diverges in the same way as described in connection with the embodiment of Figures 1 and 2.

The invention achieves the aims set by overcoming the above mentioned disadvantages of the prior art.

The provision of a superposed stretch having the aforesaid length, downstream of the print head, where ribbon and web are fed forward one on top of the other allows the ink to be effectively transferred from the print ribbon to the adhesive-coated web. During their transit along the superposed stretch, web and ribbon remain in contact and the ink has all the time needed to be transferred completely, making a good quality print of the graphical design and/or caption on the adhesive-coated web.

Moreover, the provision of the superposed stretch having the specific length values stated above, by increasing the efficiency of ink transfer, makes it possible to reduce the temperature necessary for the printing process and the pressure applied by the print head. The reduced temperature and pressure benefit both the print head, which is thus subjected to less onerous working conditions, and the adhesive-coated web which is locally heated at lower temperatures and thus tends to adhere less strongly to the print ribbon, and the very same print ribbon, which is less weakened and hence less subject to the risk of breaking. Furthermore, the superposed stretch having the specific length values stated above makes it possible to provide blowing means under the adhesive-coated web to direct a flow of air at the web in order to cool it (it should be considered that a space of less than 12 millimetres is not large enough to fit the blower means).

Surprisingly, the Applicant has found that even a superposed stretch having a length "T" of less than approximately 40 mm, does not have appreciable penalizing effects on productivity (linked to the backward movements of the adhesive-coated web after being cut) but does have very important benefits in terms of reduced wear and working efficiency.

Also surprisingly, the Applicant has found that it is possible to obtain the above mentioned values for the angle of divergence (120 degrees or even more) by simply increasing the length of the superposed stretch "T", which, it must be remembered, is consistent with what is necessary to achieve the above mentioned advantages.

Claims

1. A labelling machine comprising:

- first feed means (3, 14, 25) designed to advance an adhesive-coated web (2) along a first feed path (PI);

- second feed means (11, 12) designed to advance a print ribbon (8) along a second feed path (P2) having at least one stretch (S) superposed over the first feed path (PI), the print ribbon (8) bearing a layer of ink on at least one side of it;

- a print head (7) located on the first feed path (PI) and operating on the print ribbon (8) in such a way as to thermally transfer ink from the print ribbon (8) to the adhesive-coated web (2);

characterized in that the superposed stretch (S) extends downstream of the print head (7) for a length (T) greater than or equal to 12 millimetres.

2. The machine according to claim 1, wherein the superposed stretch (S) extends downstream of the print head (7) for a length greater than or equal to 15 millimetres and preferably greater than or equal to 20 millimetres.

3. The machine according to claim 1 or 2, wherein, at the end of the superposed stretch (S), the second path (P2) comprises a diversion from the first path (PI) according to a diversion angle (a) which is greater than 90 degrees, preferably greater than 110 degrees and even more preferably greater than 120 degrees, for promoting detachment between the print ribbon (8) and the adhesive- coated web (2).

4. The machine according to claim 3, wherein, downstream of the print head (7), the second feed means (11, 12) comprise a detachment blade (12) having a pointed tip which is directed away from the print head (7) and round which the print ribbon (8) is trained in such manner as to produce the divergence of the print ribbon (8).

5. The machine according to claim 3, wherein the superposed stretch (S) is straight and extends between the print head (7) and the detachment blade (12).

6. The machine according to any of the foregoing claims, further comprising blowing means (20) facing the adhesive-coated web (2) at the superposed stretch (S) in order to direct a cooling air flow at the adhesive-coated web (2) in such a way as to keep the adhesive-coated web (2) pressed against the print ribbon (8).

7. The machine according to any of the foregoing claims, wherein the first feed means (3, 14, 25) comprise a supporting roller (3) facing the print head (7) and tangent to the first path (PI), the supporting roller (3) having an outside surface (3a) constituting a contact surface for the print head (7).

8. The machine according to any of the foregoing claims, further comprising a cutting station (13) located downstream of the superposed stretch (S) to divide the adhesive-coated web (2) into ready-to-use adhesive labels.

9. The machine according to any of the foregoing claims, wherein the first feed means (3, 14, 25) comprise motor means designed to move the adhesive-coated web (2) according to an alternating feed motion along the first feed path (PI), and wherein the second feed means (11, 12) are designed to advance the print ribbon (8) according to a continuous, or intermittent, feed movement along the second feed path (P2).

10. The machine according to any of the foregoing claims, wherein the length (T) of the superposed stretch (S) is less than 40 millimetres.