EP3370969A1

EP3370969A1 - Device for the polymerization of inks and/or paints in an inert atmosphere

Info

Publication number: EP3370969A1
Application number: EP16822523.3A
Authority: EP
Inventors: Alberto MAIANO
Original assignee: Uv Ray Srl
Current assignee: Uv Ray Srl
Priority date: 2015-11-03
Filing date: 2016-11-02
Publication date: 2018-09-12
Anticipated expiration: 2036-11-02
Also published as: WO2017077460A1; EP3370969B1

Abstract

A device (1) for the polymerization of inks and/or paints, comprises a polymerization chamber (2) having an inlet slot (3) for inserting a printed and/or painted support (S) and an outlet slot (4) for ejecting the support (S); filling means (7) associated with the chamber (2) for introducing inert gas into the chamber (2); radiation means (8) associated with the chamber (2) for radiating the support (S) with electromagnetic radiation and causing the polymerization of a paint and/or ink layer present on the support (S); a first movement member (19) of the inert gas placed close to the inlet slot (3) for moving the inert gas from the interior of the chamber (2) towards the inlet slot (3).

Description

DEVICE FOR THE POLYMERIZATION OF INKS AND/OR PAINTS IN AN INERT ATMOSPHERE

FIELD OF THE INVENTION

The present invention relates to a device for the polymerization of inks and/or paints. In particular, such a device can be used in printing machines and/or coating machines employing inks, paints, lacquers and the like which are fixed through polymerization, i.e. a chemical reaction which is able to change the molecular structure of components.

More specifically, reference is made herein to printing machines and/or coating machines, for example but not limited to graphic art printing machines using ultraviolet light sources to cause the polymerization of the ink, paint or lacquer used. PRIOR ART

As is known, in printing processes, such as but not limited to flexographic printing processes, ultraviolet light sources are used for the polymerization of inks, paints and the like.

In the printing machines of the type considered herein, it is known to move the support, such as paper but also films made of polymeric material, so that it passes through several printing stations.

Various rollers sequentially placed perform the inking of the support.

This type of printing has the advantage of being used on many supports: paper, cardboard, plastic, aluminum, and others. It allows to use water, UV or solvent colors, at a printing speed.

In particular, the use of UV reactive inks further speeds up the printing process by including quick drying thereof by exposure to ultraviolet light.

It is therefore known to use ultraviolet devices, commonly referred to as "lamps", for drying the inks used in the printing processes in high speed coil on paper supports, and the results which can be achieved are good.

More specifically, a device for the polymerization of inks and/or paints of the type known from the prior art comprises a polymerization chamber. Such a polymerization chamber has an inlet slot for inserting a printed and/or painted support and an outlet slot for ejecting the support once the polymerization has been completed.

Since a predetermined chemical reaction should take place inside the chamber, the oxygen concentration therein should be minimized. To this end, in use, the chamber is saturated with inert gas, preferably nitrogen. As a result, the device comprises filling means associated with the chamber and configured to introduce inert gas into the chamber. As mentioned above, the device comprises radiation means associated with the chamber and configured to radiate the support with electromagnetic radiation to cause the polymerization of a paint and/or ink layer present on the support. Such radiation means comprise a UV lamp. As a result, the chamber has at least one UV radiation-transparent wall.

In use, the support is inserted into the chamber through the inlet slot so that one painted and/or inked side is irradiated by UV light. The support is then removed through the outlet slot.

Disadvantageously, having to provide the inlet for a continuous support, the camber of the known device is not air-tight. As a result, there will be leaks of inert gas and, more disadvantageously, an undesired infiltration of air containing oxygen from the external environment. This would tend to degrade the performance of the polymerization device and, therefore, is a problem already solved in the prior art. The solution, however, consists in increasing the nitrogen introduced into the chamber to compensate for such infiltrations, thereby enormously increasing the consumption of this gas and the costs associated therewith.

WO 96/34700 A1 describes a method and an apparatus for hardening a layer of ink, paint, adhesive or silicone on a substrate of paper, plastic, wood or metal. The apparatus comprises a housing, which is open in the direction of a transport body of the substrate and covers the substrate while leaving free inlet and outlet openings of the substrate in/from the housing. The apparatus further comprises a UV lamp and a reflector, both arranged in the housing, the reflector being configured to direct the UV rays emitted by the UV lamp on the substrate passing into the housing. A gas conduit introduces gas into the housing. The apparatus further comprises gas recovery nozzles positioned adjacent to the inlet and/or outlet openings of the housing and adapted to direct the gas onto the substrate in input and in output in/from the housing, respectively. Each nozzle has a body, which is glued and screwed to the housing, and an opening adjustable in width by means of a screw. SUMMARY

Within this context, the technical task underlying the present invention is to propose a device for the polymerization of inks and/or paints according to the present invention which overcomes the above drawbacks of the prior art.

In particular, it is the main object of the present invention to provide a device for the polymerization of inks and/or paints able to minimize the consumption of nitrogen. It is another object of the present invention to provide a device for the polymerization of inks and/or paints able to minimize the presence of oxygen in the chamber, in particular close to the support.

The specified technical task and the specified objects are substantially achieved by a device for the polymerization of inks and/or paints according to the present invention comprising the technical features set out in one or more of the appended claims.

In particular, the device according to the present invention comprises a polymerization chamber. Such a polymerization chamber has an inlet slot for inserting a printed and/or painted support. The chamber also has an outlet slot for ejecting such a support.

Filling means are associated with the chamber. Such filling means are configured to introduce inert gas into the chamber itself.

Radiation means are further associated with the chamber. The radiation means are configured to radiate the support with an electromagnetic radiation, so as to cause the polymerization of a paint and/or ink layer present on the support.

A first member for moving the inert gas is placed close to the inlet slot. Such a movement member is configured to move the inert gas from the interior of the chamber towards the inlet slot. In particular, the first movement member has a side surface and a longitudinal development axis and is rotatable about such a longitudinal development axis in such a direction of rotation that the speed of the side surface close to the support has an opposite direction with respect to the feeding speed of the support.

Advantageously, the first movement member allows the dragging effect of the support to be counterbalanced, which tends to drag air from the outside to the interior of the chamber. Therefore, a small amount of inert gas present into the chamber is ejected but at the same time, the entry of air from the outside is strongly limited. The result of these two effects is still a net reduction in the consumption of nitrogen compared to that found in the known solution of the prior art.

The device may further comprise a second movement member placed close to the outlet slot. Such a second movement member is configured to move the inert gas from the outlet slot to the interior of the chamber. In particular, and similar to the first movement member, the second movement member has a side surface and a longitudinal development axis and is rotatable about such a longitudinal development axis in such a direction of rotation that the speed of the side surface close to the support has an opposite direction with respect to the feeding speed of the support.

Advantageously, in this manner, the amount of nitrogen escaping from the outlet slot dragged by the support is decreased. Therefore, a further reduction in the consumption of nitrogen is achieved.

The filling means mentioned above can further comprise at least one inert gas distribution member placed close to the inlet slot and/or the outlet slot. Such a distribution member is configured to evenly distribute the inert gas along at least part of the extension of the slot.

Advantageously, the distribution member close to the inlet slot or the outlet slot collaborates with the movement member already present close to the slot. In fact, a constant flow of nitrogen evenly distributed close to the support is ensured. Any oxygen residues are thus eliminated, improving the printing quality.

LIST OF DRAWINGS

Further features and advantages of the present invention will become more apparent from the indicative, non-limiting description of a preferred but non- exclusive embodiment of a device for the polymerization of inks and/or paints in an inert atmosphere, as shown in the accompanying drawings, in which: - figure 1 is a schematic side view of a device for the polymerization of inks and/or paints according to the present invention; and

- figure 2 is a plan view of the device in figure 1 with some parts removed to better show others.

DETAILED DESCRIPTION

With particular reference to the accompanying figures, reference numeral 1 indicates a device for the polymerization of inks and/or paints according to the present invention.

Device 1 comprises a polymerization chamber 2 which has an inlet slot 3 for inserting a printed and/or painted support "S" and an outlet slot 4 for ejecting support "S". By way of example only, support "S" may be schematized as a continuous sheet having a printed surface "ST". Such a support "S" is movable along a feeding direction "A". In particular, the feeding direction "A" is perpendicular to both the inlet slot 3 and to the outlet slot 4. It should be noted, however, that since support "S" is not part of the present invention, it can still be of any type.

More in detail, device 1 comprises movement means (not shown) of support "S", such movement means comprise at least one motorized roller. A plurality of further rollers 6 are placed underneath support "S", in particular on the side opposite to the printed surface "ST", so as to support it.

With reference in particular to figure 1 , device 1 comprises filling means 7 associated with chamber 2. Such filling means 7 are configured to introduce inert gas, preferably nitrogen, into chamber 2. The filling means 7 will be described in detail in a following part of the present description.

Device 1 further comprises radiation means 8 associated with chamber 2. Such radiation means 8 are configured to radiate support "S" with an electromagnetic radiation to cause the polymerization of a paint and/or ink layer present on support "S". In particular, the radiation means 8 operate in a radiation area 2a of chamber 2.

More in detail, the radiation means 8 comprise a UV lamp 9. Such a lamp 9 faces the printed surface "S" of support "S". The power of lamp 9 is calibrated according to the feeding speed of support "S", so as to provide the right amount of UV radiation to cause a complete polymerization on support S. Optionally, the radiation means 8 may comprise a mirror 10 placed behind lamp 9, capable of concentrating the UV radiation of lamp 9 on support "S", thereby allowing the use of a low-power lamp 9. Further details about a particularly advantageous embodiment of the radiation means 8 are found in patent application IT 10 2015 902331688 to the same Applicant. Such radiation means may also be employed in the device 1 disclosed in the present description.

The filling means 7 comprise at least one inert gas distribution member 1 1 placed close to the inlet slot 3 and/or the outlet slot 4. The distribution member 1 1 is configured to evenly distribute the inert gas along at least part of the extension of slot 3, 4 to which it is applied. Within the context of the present description, the term "extension" means the prevailing dimension of each of slots 3, 4. As is shown in the accompanying drawings, such a prevailing dimension substantially extends in a direction perpendicular to the feeding direction "A" support "S" and substantially parallel to the plane of support "S" itself.

More in detail, the distribution member 1 1 is configured to evenly distribute the inert gas along at least 60% of the extension of slot 3, 4, and preferably as much as possible along 100% of the extension of slot 3, 4.

In further detail, device 1 preferably comprises a pair of distribution members 1 1 , placed at the inlet slot 3 and at the outlet slot 4, respectively. In other words, the distribution members 1 1 are placed outside the radiation area 2a of chamber 2. In yet other words, the radiation zone 2a is placed between the distribution members 1 1 .

In particular, the distribution member 1 1 has a cavity 12 placed in fluid communication with a source of inert gas. Such an inert gas source may be a nitrogen cylinder, commercially available. Cavity 12 has a plurality of first nozzles 13, each placed close to slot 3, 4. The first nozzles 13 are substantially aligned, thereby defining a dispensing line substantially parallel to slot 3, 4. In practice, in the preferred embodiment, cavity 12 is a tube, closed at the ends, on the side surface of which holes are obtained for defining the first nozzles 13 already mentioned. The distribution member 1 1 further comprises a conduit 14 placed in fluid communication with a source of inert gas. In practice, the cavity 12 mentioned above is placed in fluid communication with the source thereof through conduit 14. In particular, conduit 14 is inserted into cavity 12 and is placed in fluid communication with cavity 12 so as to saturate it with the inert gas.

In greater detail, conduit 14 has a plurality of second nozzles 15 opening into cavity 12. The second nozzles 15 have a smaller passage area than a passage area of the first nozzles 12. Within the context of the present description, "passage area" means the total area of the first 13 and second nozzles 1 5, respectively. Accordingly, a greater area of the second nozzles 15 can be obtained by increasing the number of second nozzles 15 with respect to the first nozzles 13 with the same section of each nozzle. Alternatively or in combination, the size of each first nozzle 15 may also be increased with respect to a single first nozzle 13.

Device 1 comprises at least a first movement member 19 for the inert gas. In particular, such a first movement member 19 is placed close to the inlet slot 3, and is configured to move the inert gas from the interior of chamber 2 towards the inlet slot 3. In other words, the first movement member 19 is placed between the distribution member 1 1 close to the inlet slot 3 and the inlet slot 3 itself. Preferably, the first movement member 19 is inserted into a containment compartment 2b of chamber 2. A partition 22 separates the containment compartment 2b from the rest of chamber 2. Such a partition 22 is therefore placed between the first movement member 19 and the distribution member 1 1 closest to the inlet slot 3. The first movement member 19 has the function of countering the action of support "S", which would tend to bring air from the external environment towards the interior of chamber 2.

In greater detail, the first movement member 19 has a prismatic shape, preferably cylindrical. Such a first movement member 19 has a side surface 20 and a longitudinal development axis "L1 " which, in particular, is an axis of symmetry of said first movement member 19. Accordingly, the side surface 20 is symmetrical with respect to the longitudinal development axis "L1 ". The longitudinal development axis "L1 " is in particular oriented along a direction substantially parallel with respect to the outlet slot 4. The first movement member 19 is rotatable with respect to the longitudinal development axis "L1 " thereof. The direction of rotation of the first movement member 19 is such that the speed of the side surface 20 close to support "S" has an opposite direction with respect to the feeding speed of support "S" itself. In this way, the air which would tend to penetrate into chamber 2 through the inlet slot 3 is stopped by a flow of inert gas generated by the rotation of the first movement member 19.

In greater detail, the side surface 20 of the first movement member 19 has an area proximal to the inlet slot 3, through which support "S" entering chamber 2 passes. The side surface 20 is movable approaching the inlet slot 3 along such a proximal area.

To improve the efficacy of the inert gas dragging effect of the first movement member 19, the side surface 20 has a plurality of bumps 21 . Such bumps 21 have the function of triggering a turbulent motion in the vicinity of the side surface 20 of the first movement member 19. In the embodiment shown, bumps 21 may consist of recesses obtained on the side surface 20 of the first movement member 19. Advantageously, the rotation of the movement member 19 together with the presence of said partition 22 causes the onset of a high-pressure area inside the containment compartment 2b of chamber 2.

In the preferred embodiment, device 1 also comprises a second movement member 16 for the inert gas. Such a second movement member 16 is placed close to the outlet slot 4, and is configured to move the inert gas from the outlet slot 4 towards the interior of chamber 2. In other words, the second movement member 16 counteracts the action of support "S", which would tend to drag the inert gas therewith out of chamber 2. In other words, the second movement member 16 counteracts the action of support "S", which would tend to drag the inert gas therewith out of chamber 2.

Structurally, the second movement member 16 is made in a similar way to the first movement member 19 and therefore has a prismatic shape, preferably cylindrical. In particular, the second movement member 16 has a side surface 17, similar to the side surface 20 of the first movement member 19 and a longitudinal development axis "L2".

In particular, the longitudinal development axis "L2" is an axis of symmetry of the second movement member 16. Accordingly, the side surface 17 is symmetrical with respect to the longitudinal development axis "L2". The longitudinal development axis "L2" is in particular oriented along a direction substantially parallel with respect to the outlet slot 4.

In order to improve the efficacy of the dragging effect of the second movement member 16, the side surface 17 has a plurality of bumps 18, 21 similar to bumps 21 of the side surface 20 of the first movement member 19. Such bumps, similar to bumps 21 of the first movement member 19, have the function of triggering a turbulent motion in the vicinity of the side surface 17 of the second movement member 16. Preferably, bumps 18 may consist of recesses obtained on the side surface 17.

The second movement member 16 is rotatable with respect to the longitudinal development axis "L2" thereof, similar to the longitudinal axis "L1 " of the first movement member 19 and preferably parallel thereto. The direction of rotation of the second movement member 16 is such that the speed of the side surface 17 thereof close to support "S" has an opposite direction with respect to the feeding speed of support "S" itself. In this way, the inert gas which would tend to escape from chamber 2 through the outlet slot 4 is returned back by the rotation of the second movement member 16.

In greater detail, the side surface 17 of the second movement member 16 has an area proximal to the outlet slot 4, through which support "S" exiting from chamber 2 passes. The side surface 17 is movable away from the outlet slot 4 along such a proximal area.

In other words, the side surface 17 of the second movement member 16 has an area proximal to the outlet slot 4. The side surface 17 of the second movement member 16 is movable away from the outlet slot 4 along such a proximal area.

Claims

1 . A device (1 ) for the polymerization of inks and/or paints, comprising a polymerization chamber (2) having an inlet slot (3) for inserting a printed and/or painted support (S) and an outlet slot (4) for ejecting said support (S); filling means (7) associated with said chamber (2) and configured to introduce inert gas into said chamber (2); radiation means (8) associated with said chamber (2) and configured to radiate said support (S) with electromagnetic radiation to cause the polymerization of a paint and/or ink layer present on said support (S); and a first movement member (19) of said inert gas placed close to said inlet slot (3), characterized in that

said first movement member (19) is configured to move said inert gas from the interior of said chamber (2) towards the inlet slot (3) and has a side surface (20) and a longitudinal axis (L1 ), said first movement member (19) being rotatable about said longitudinal development axis (L1 ) in such a direction of rotation that the speed of said side surface (20) close to the support (S) has an opposite direction with respect to the feeding speed of the support (S).

2. A device (1 ) according to claim 1 , characterized in that said chamber (2) has a containment compartment (2b), said first movement member (19) being inserted in said containment compartment (2b).

3. A device (1 ) according to claim 2, characterized in that it comprises a partition (22) for defining said containment compartment (2b), said partition (22) being placed between the first movement member (19) and the filling means (7).

4. A device (1 ) according to any one of the preceding claims, characterized in that said longitudinal development axis (L1 ) of said first movement member (19) is arranged along a direction substantially parallel to said inlet slot (3).

5. A device (1 ) according to any one of the preceding claims, characterized in that said side surface (20) of said first movement member (19) is symmetric with respect to said longitudinal development axis (L1 ).

6. A device (1 ) according to any one of the preceding claims, characterized in that said side surface (20) has an area proximal to said inlet slot (3), said side surface

(20) being movable approaching said inlet slot (3) along said proximal area.

7. A device (1 ) according to any one of the preceding claims, characterized in that said side surface (20) has a plurality of bumps (21 ).

8. A device (1 ) according to claim 7, characterized in that said bumps (21 ) are recesses obtained on said side surface (20) of said first movement member (19).

9. A device (1 ) according to any one of the preceding claims, characterized in that it comprises a second movement member (16) placed close to said outlet slot (4) and configured to move said inert gas from the outlet slot (4) towards the interior of said chamber (2), said second movement member (16) having a side surface (17) and a longitudinal development axis (L2), said second movement member (16) being rotatable with respect to said longitudinal development axis (L2) in such a direction of rotation that the speed of said side surface (17) close to the support (S) has an opposite direction with respect to the feeding speed of the support (S).

10. A device (1 ) according to claim 9, characterized in that said longitudinal development axis (L2) is arranged along a direction substantially parallel to said outlet slot (4).

1 1 . A device (1 ) according to claim 9 or 10, characterized in that said side surface (17) of said second movement member (16) is symmetric with respect to said longitudinal development axis (L2).

12. A device (1 ) according to any one of claims 9 to 1 1 , characterized in that said side surface (16) of said second movement member (16) has an area proximal to said outlet slot (4), said side surface (17) being movable away from said outlet slot (4) along said proximal area.

13. A device (1 ) according to any one of claims 9 to 12, characterized in that said side surface (17) has a plurality of bumps (18).

14. A device (1 ) according to claim 13, characterized in that said bumps (18) are recesses obtained on said side surface (20).

15. A device (1 ) according to any one of the preceding claims, characterized in that said filling means (7) comprise at least one distribution member (1 1 ) of said inert gas placed close to said inlet slot (3) and/or said outlet slot (4) and configured to evenly distribute said inert gas along at least a part of the extension of said slot (3, 4).

16. A device (1 ) according to claim 15, characterized in that said at least one distribution member (1 1 ) is configured to evenly distribute said inert gas along at least 60% of the extension of said slot (3, 4), preferably along 100% of the extension of the slot (3, 4).

17. A device (1 ) according to any one of the preceding claims, characterized in that it comprises a pair of distribution members (1 1 ), placed at said inlet slot (3) and said outlet slot (4), respectively.

18. A device (1 ) according to any one of claims 15 to 17, characterized in that said at least one distribution member (1 1 ) comprises a cavity (12) placed in fluid communication with a source of inert gas, said cavity (12) having a plurality of first nozzles (13), each placed close to said slot (3, 4), said first nozzles (13) being substantially aligned and defining a dispensing line substantially parallel to said slot (3, 4).

19. A device (1 ) according to claim 18, characterized in that said distribution member (1 1 ) comprises a conduit (14) placed in fluid communication with an inert gas source, said conduit (14) being inserted in said cavity (12) and being placed in fluid communication with said cavity (12) in order to saturate said cavity (12) with inert gas.

20. A device (1 ) according to claim 19, characterized in that said conduit (14) has a plurality of second nozzles (15) opening into said cavity (12), said second nozzles

(15) having a smaller passage area with respect to a passage area of said first nozzles (13).