Embossing and lamination assembly with heated rolls and related hot embossing and lamination method

Abstract

An embossing and lamination assembly with heated rolls comprises two pairs of steel / rubber rolls between which respectively a first paper ply (11A) and a second paper ply (11B) are fed, in which an upper steel embossing roll (21) is coupled with an upper rubber embossing counter roll (22) and a lower steel embossing roll (31) is coupled with a lower rubber embossing counter roll (32), as well as comprises a glue-distributing assembly (40), provided with an anilox roll (42) and a glue applicator roll (41), placed in contact on a side of said upper steel embossing roll (21), and a coupling roll (13), placed in contact on the opposite side of said upper steel embossing roll (21), and comprises heating means (50) associated with at least one of said upper steel embossing roll (21) and said lower steel embossing roll (31), as well as comprises an auxiliary joining device of the plies (60) of the two paper plies (11A, 11B) adapted to be selectively activated and deactivated depending on the driving speed of the embossing and lamination assembly. A related hot embossing and lamination method also forms part of the invention.

Description

[0001] The present invention refers to an embossing and lamination assembly with heated rolls and to a related hot embossing and lamination method.

[0002] It is known from EP3747644A1 to equip in an embossing and lamination assembly one or both steel rolls for embossing with heating means adapted to heat the surface thereof to perform embossing on the related paper ply during the heating thereof.

[0003] This process, despite offering a number of advantages with respect to the traditional embossing, particularly in relation to the final effect generated on the plies, introduces some critical issues compared to a traditional embossing and cold lamination process.

[0004] A drawback concerns the reliability of gluing by means of the glue assembly of the embossing and lamination assembly at the start of the line, that is, approximately below 150-200 m / min.

[0005] In particular, at the start of a converting line, which includes an embossing and lamination assembly in which the steel embossing roll to which the glue-distributing assembly is coupled is heated, there may be problems in gluing the plies, due to the fact that the heated upper steel embossing roll causes the entire zone of the glue-distributing assembly to be heated. As a result, the glue applicator roll, the so-called cliché roll, is wetted by the screened roll, the so-called anilox roll, to deliver the glue to the paper ply, but the glue evaporates before it can be transferred to the paper. This occurs because the evaporation time of the glue is shorter than the transfer time to the paper when the machine is not yet at production speed, said driving speed, approximately set above 150-200 m / min.

[0006] If gluing does not occur, in the station of the converting line following the embossing and lamination assembly, the rewinder does not carry out the transfer because the plies are separated and the process is interrupted with the formation of a paper wad, which requires the entire line to be stopped.

[0007] A further drawback introduced by the heating of one or more steel embossing rolls in an embossing and lamination assembly concerns the risk of damage to the upper and / or lower rubber embossing counter rolls, as well as to all the rolls facing the heated steel embossing rolls, such as the coupling roll, or marriage roll, and the glue applicator roll of the glue assembly, which are directly exposed to heat during machine operation, but especially in the event of a machine stop. Indeed, during machine operation, the paper transferred through the embossing and lamination assembly at speed is capable of taking part of the heat, while in the event of a machine stop, the rolls statically facing the hot steel embossing rolls risk to be subjected to a rapid surface deterioration and even to the deformation thereof.

[0008] An object of the present invention is to make an embossing and lamination assembly with heated rolls and a related hot embossing and lamination method that overcomes the above-mentioned drawbacks of the prior art.

[0009] Another object of the present invention is to make an embossing and lamination assembly with heated rolls and a related hot embossing and lamination method that is particularly simple and functional, with low costs.

[0010] These objects according to the present invention are achieved by making an embossing and lamination assembly with heated rolls and a related hot embossing and lamination method as set forth in claim 1.

[0011] Further features are provided in the dependent claims.

[0012] The features and advantages of an embossing and lamination assembly with heated rolls and a related hot embossing and lamination method according to the present invention will be more apparent from the following description, which is exemplary and non-limiting, referred to the attached schematic drawings in which: Figure 1A is a schematic view of an embossing and lamination assembly with heated rolls according to the present invention, in which the paper is fed according to a path that does not wrap the rubber embossing counter rolls; Figure 1B is a schematic view of an embossing and lamination assembly with heated rolls according to the present invention, in which the paper is fed according to a path wrapping the rubber embossing counter rolls; Figure 2A schematically shows the embossing and lamination assembly of Figure 1, in which the rubber embossing counter rolls, provided with an auxiliary motorization, are moved away from the steel embossing rolls; Figure 2B shows the auxiliary motorization of Figure 2A viewed from the transmission side; Figure 3 schematically shows the embossing and lamination assembly in which the glue-distributing assembly is moved away from the steel embossing roll; Figure 4 schematically shows the embossing and lamination assembly of Figure 1, in which the coupling roll is moved away from the steel embossing roll; Figure 5 schematically shows the independent motorizations for the steel embossing rolls, for the coupling roll, for the glue applicator roll, for the anilox roll, and for the outgoing draw station of the embossing and lamination assembly with heated rolls.

[0013] With reference to the figures, an embossing and lamination assembly with heated rolls, overall indicated by 10, is shown, depicted and described according to the exemplary and non-limiting embodiment that processes two paper plies 11A, 11B to form laminated multi-ply tissue paper 11.

[0014] According to the invention, the embossing and lamination assembly can treat a single upper ply and a single lower ply or even multiple plies together, for example, two upper plies and one lower ply, one upper ply and two lower plies, two upper plies and two lower plies.

[0015] In the following description, reference will be made for simplicity to the "first upper paper ply 11A" and the "second lower paper ply 11B," even if multiple plies are treated together on the upper and / or lower side.

[0016] The embossing and lamination assembly 10 comprises two pairs consisting of steel / rubber rolls, respectively comprising an upper steel embossing roll 21 and an upper rubber embossing counter roll 22, a lower steel embossing roll 31 and a lower rubber embossing counter roll 32, between which respectively the first paper ply 11A and the second paper ply 11B are fed, with the help of related return rolls 12, motorized and / or non-motorized.

[0017] The upper 21 or lower 31 steel embossing rolls can be provided with any type of protrusions defining micro-embossing, macro-embossing, or double-height embossing, or multi-height embossing, that is, arranged according to two or more different heights, as known.

[0018] "Protrusions defining micro-embossing" means protrusions of equal height, possibly defining a decorative pattern, for example, obtained with a steel embossing roll with a tip density per cm 2< greater than 40 (up to 100) and with a tip size smaller than 0.7 mm.

[0019] "Protrusions defining macro-embossing" means protrusions of equal height, possibly defining a decorative pattern, for example, obtained with a steel embossing roll with a tip density per cm 2< smaller than 40 (down to 15) and with a tip size greater than 0.7 mm (up to 1 mm) .

[0020] "Protrusions defining double-height embossing" generally means different-height protrusions, in which glue is delivered to the greater-height protrusions, and the smaller-height protrusions generally define a micro-embossed pattern.

[0021] Following the passage of the first paper ply 11A between the upper pair consisting of the steel embossing roll 21 and the upper rubber embossing counter roll 22, the protrusions of the upper steel roll 21 imprint on the first paper ply 11A related protuberances, having the same height or different heights, on the first paper ply 11A.

[0022] In the embossing and lamination assembly 10, the upper steel embossing roll 21 on one side abuts a glue-distributing assembly 40 and on the opposite side abuts a coupling roll 13, said marriage roll. In particular, the upper steel embossing roll 21 abuts a glue applicator roll 41, said cliché roll, which distributes glue that has been transferred thereto from the anilox roll 42, also coupled in turn with a glue tank 43, on the embossed paper ply. In particular, the clich6 roll 41 distributes glue on the protuberances imprinted by embossing on the first paper ply 11A.

[0023] The marriage roll 13, placed against the upper steel embossing roll 21, exerts a coupling pressure to perform the final coupling between the first ply 11A and said second ply 11B at the glue deposits, thus forming laminated multi-ply tissue paper 11.

[0024] In the case where the upper steel roll 21 is double height, following the passage of the first paper ply 11A between the pair of steel / rubber rolls, the greater-height protrusions of the upper steel roll 21 imprint on the first paper ply 11A protuberances defining a decorative pattern having a first height, and the smaller-height protrusions imprint on the same first paper ply 11A smaller-height protuberances defining a dotted background pattern, referred to as micro-embossing. In this particular case, glue is applied by the clich6 roll 41 on the greater-height protuberances of the first embossed paper ply 11A. On the opposite side, the marriage roll 13 presses the two paper plies 11A and 11B against each other to ensure their gluing, to form laminated multi-ply tissue paper 11.

[0025] The lower steel embossing roll 31 is generally provided with protrusions all of equal height. Following the passage of the second paper ply 11B between the lower pair consisting of the steel embossing roll 31 and the rubber embossing counter roll 32, the protrusions of the lower embossing roll 31 imprint on the second paper ply 11B constant-height protuberances defining a dotted background pattern, referred to as micro-embossing.

[0026] The steel embossing rolls 21, 31 of the embossing and lamination assembly 10 are not in contact with each other. Indeed, the plies are individually embossed between the pairs of steel / rubber rolls and then are pressed together by the coupling roll 13, which acts against the upper steel embossing rolls 21.

[0027] In an equivalent alternative embodiment, the glue-distributing assembly 40 and the coupling roll 13 could be associated with the lower steel embossing rolls.

[0028] Furthermore, the embossing on the steel rolls could be different from what is described.

[0029] The embossing and lamination assembly 10 according to the invention comprises heating means 50 associated with the upper steel embossing roll 21 and / or the lower steel embossing roll 31.

[0030] The heating means 50 of the steel rolls 21, 31 are configured to bring the surface of the steel roll wrapped by the paper plies 11A and 11B to a temperature between about 90°C and 200°C.

[0031] The heating means 50 can be selected from those known, both housed inside the steel roll to heat the side surface of the steel roll by conduction from the inside and housed outside the roll and facing the side surface of the steel roll to be heated by radiation and / or convection.

[0032] For example, the heating means 50 can comprise an electric resistance suitably embedded in the steel roll, or an oil, water, or steam heating circuit, also at least partly formed inside the steel roll itself, as well as an induction heating assembly facing outside the steel roll.

[0033] For exemplary purposes only, the heating means 50 have been shown in the figures only by way of example schematically through the symbol of a resistance placed on the upper 21 and lower 31 steel embossing rolls.

[0034] According to a first simplified embodiment of the invention, it is sufficient to place the heating means 50 only associated with the lower steel embossing roll 31. This solution is advantageously constructively simpler, as the lower steel roll 31 is generally only coupled with the related lower rubber roll 32 and is therefore easier to equip with the heating means 50 in terms of both dimensions and thermal interaction with other components of the machine.

[0035] A further solution of the present invention shown in the figures provides that both steel embossing rolls are equipped with heating means 50 or, possibly, that the heating means 50 are associated only with the upper steel embossing roll 21.

[0036] According to the invention, the embossing and lamination assembly comprises an auxiliary joining device of the plies 60 for joining the two plies 11A and 11B, adapted to be selectively activated and deactivated depending on the driving speed of the embossing and lamination assembly 10.

[0037] The auxiliary joining device of the plies 60 is placed outgoing from the embossing and lamination assembly, downstream of the coupling roll 13. The placement outgoing from the embossing assembly is equivalently understood to also comprise the positioning of the auxiliary joining device of the plies 60 at the inlet to the subsequent rewinding station upstream of the winding.

[0038] The auxiliary joining device of the plies 60 comprises a mechanical ply bonding unit placed outgoing from the embossing and lamination assembly in contact with a first roll 14' of an outgoing draw station 14 (figures 1A and 1B).

[0039] The auxiliary joining device of the plies 60 could alternatively, according to the invention, comprise other auxiliary means of joining the plies, not shown.

[0040] In the embossing and lamination assembly 10, the upper 22 and / or lower 32 rubber embossing counter rolls are preferably mounted on a mobile arm 24, 34 when the related steel roll 21, 31, to which they are coupled, is equipped with heating means 50. Indeed, in the event of a machine stop, it is advantageous to move the rubber embossing counter roll 22, 32 away from the heated steel embossing roll 21, 31 to avoid damaging the rubber surface due to the high temperature (as schematically shown in figure 2A).

[0041] Furthermore, the glue-distributing assembly 40 is preferably mounted on a slide 43 provided with a linear excursion of at least 100 mm, to allow the glue-distributing assembly 40 to move away from the hot upper steel embossing roll 21 in the event of a machine stop, by a greater extent than generally occurs in known embossing and lamination assemblies (as schematically shown in figure 3).

[0042] The coupling roll 13, which in known embossing and lamination assemblies is also generally mounted on a mobile arm 13' and provided with an excursion away from the upper steel embossing roll 21 of about 10 mm, can advantageously be provided with a greater excursion away, equal to at least 100 mm (as schematically shown in figure 4).

[0043] Furthermore, the upper 22 and / or lower 32 rubber embossing counter rolls are preferably each provided with an auxiliary motorization 15, selectively activable and deactivable.

[0044] Figures 2A and 2B show the example of an auxiliary motorization 15 for the upper rubber embossing counter roll 22, acting through belt transmission 115 when the upper rubber embossing counter roll 22 is detached from the upper steel embossing roll 21. Similarly, the lower rubber embossing counter roll 32, when facing the heated lower steel embossing roll 31, is also provided with the independent auxiliary motorization 15, acting through belt transmission 115.

[0045] The belt transmission 115 provides for the interposition of a motorized axis 15' between the auxiliary motorization 15 and the rubber embossing counter roll 22, 32.

[0046] Arranging an auxiliary motorization 15 for the upper 22 and / or lower 32 rubber embossing counter rolls, when facing the heated upper 21 and / or lower 31 steel embossing rolls, advantageously allows for a paper passage wrapping the rubber embossing counter roll 22, 32 even at an angle greater than 90°, as shown in figure 1B. This path of the paper plies 11A and 11B advantageously makes additional return rolls superfluous to convey the paper ply tangentially through the contact zone of the pair of steel / rubber embossing rolls, the so-called nip.

[0047] Indeed, in the case of a machine at jog mode, that is a low-speed driving mode (usually 5 m / min) used, for example, for paper passage or operator intervention in case of process problems, according to the invention, the upper 22 and / or lower 32 rubber embossing counter roll is opened and simultaneously put in rotation with the machine by the auxiliary motorization 15, which serves only in the case of jog mode and is disengageable with the machine at driving mode. Once the machine is placed at driving mode, the upper 22 and / or lower 32 rubber embossing counter roll closes and idly rotates dragged by the upper 21 and / or lower 31 steel embossing roll.

[0048] In the condition of the upper 22 and / or lower 32 rubber embossing counter roll detached from the upper 21 and / or lower 31 steel embossing roll, if the same were idle and wrapped by the paper at an angle greater than 90°, a jog mode would not be possible because it would tend to break the paper ply.

[0049] The embossing and lamination assembly 10 according to the invention further preferably comprises independent motorizations also for the upper 21 and / or lower 31 steel embossing roll, or for the pair consisting of the upper 21 and lower 31 steel embossing rolls, and / or for the glue applicator roll 41, and / or for the anilox roll 42, and / or for the coupling roll 13.

[0050] Figure 5 schematically shows, by way of example, all the above-mentioned motorizations acting in direct drive or acting through belt transmission. According to the invention, only some of them may also be present.

[0051] Figure 5 shows independent motorizations 16 for the upper steel embossing roll 21 and lower steel embossing roll 31, respectively, acting through respective belts 116; an independent motorization 17 for the glue applicator roll 41 and an independent motorization 18 for the anilox roll 42, both in direct drive, as well as an independent motorization 19 for the coupling roll 13, schematized through a motorized axis preferably driven by belt transmission, not shown.

[0052] Instead, Figure 1A shows a paper path in which the upper paper ply 11A is fed around idle and / or motorized rolls 12, not to wrap the respective upper rubber embossing counter roll 22, allowing it to be opened, being left idle, for the jog mode, without being subject to constraints given by the paper plies.

[0053] What is described in relation to the auxiliary joining device 60, the spacing means of the glue-distributing assembly 40, the upper 22 and / or lower 32 rubber embossing counter rolls, the coupling roll 13, and the independent motorizations of the respective components can be individually employed in an embossing and lamination assembly with heated rolls according to the present invention or employed in any mutual combination.

[0054] The hot embossing and lamination method actuated on the embossing and lamination assembly 10 described above provides to perform an auxiliary step of joining the two plies downstream of the coupling roll 13 when the embossing and lamination assembly 10 proceeds at a driving speed lower than a predeterminable speed x.

[0055] In order to perform the auxiliary step of joining the plies, the auxiliary joining device of the plies 60 is selectively activated when the embossing and lamination assembly 10 proceeds at a driving speed lower than a predeterminable speed x and deactivated when it exceeds it. In particular, the predeterminable driving speed x under which the auxiliary joining device of the plies 60 is activated is equal to about 150-200 m / min.

[0056] The activation and deactivation of the auxiliary joining device of the plies 60 is preferably performed respectively by closing and opening the mechanical ply bonding unit placed outgoing from the embossing and lamination assembly, particularly in contact with the first roll 14' of the outgoing draw station 14, preferably provided with its own motorization 20.

[0057] According to the invention, the operation of the embossing and lamination assembly with heated rolls preferably provides that at stop mode: the upper 22 and / or lower 32 rubber embossing counter rolls are detached from the upper 21 and / or lower 31 steel embossing rolls and are stopped; the anilox roll 42 and the glue applicator roll 41 are detached from the upper steel embossing roll 21 and from each other, and the anilox roll 42 is placed in rotation to remain wet by the glue and the glue applicator roll 41 is placed in slow rotation, for example, equal to 1 m / min, in which the anilox roll 42 and the glue applicator roll 41 are placed in rotation each by its own independent motorizations 18, 17; the coupling roll 13 is detached from the upper steel embossing roll 21 and placed in slow rotation, for example, equal to 1 m / min, by its own independent motorization 19.

[0058] According to the invention, the operation of the embossing and lamination assembly with heated rolls preferably provides that at jog mode: the upper 22 and / or lower 32 rubber embossing counter rolls are detached from the upper 21 and / or lower 31 steel embossing rolls and are placed in rotation at jog mode speed, for example, at 1 m / min or 5 m / min, by their own independent motorizations 15; the anilox roll 42 and the glue applicator roll 41 are detached from the upper steel embossing roll 21 and from each other, and the anilox roll 42 is placed in rotation to remain wet by the glue and the glue applicator roll 41 is placed in slow rotation, for example, equal to 1 m / min, in which the anilox roll 42 and the glue applicator roll 41 are placed in rotation each by its own independent motorizations 18, 17; the coupling roll 13 is detached from the upper steel embossing roll 21 and placed in slow rotation, for example, equal to 1 m / min, by its own independent motorization 19.

[0059] According to the invention, the operation of the embossing and lamination assembly with heated rolls preferably provides that at driving mode: the upper 22 and / or lower 32 rubber embossing counter rolls are placed under pressure on the upper 21 and / or lower 31 steel embossing rolls and dragged in idle rotation therefrom; the anilox roll 42 is placed in contact with the glue applicator roll 41, the glue applicator roll 41 is placed in contact with the upper steel embossing roll 21, and the anilox roll 42 and the glue applicator roll 41 are placed in rotation at operating speed by their own independent motorizations 18, 17; the coupling roll 13 is placed under pressure on the upper steel embossing roll 21 and placed in rotation at operating speed by its own independent motorization 19.

[0060] The embossing and lamination assembly with heated rolls and the related hot embossing and lamination method of the present invention have the advantage of improving the efficiency of joining the plies between the two plies at any step of the process, even at machine starting.

[0061] Furthermore, various components that cooperate with the heated upper and / or lower steel embossing roll are advantageously protected from heat in the event of a machine stop and jog mode.

[0062] The embossing and lamination assembly with heated rolls thus conceived is susceptible to numerous modifications and variants, all falling within the invention; furthermore, all details are replaceable with technically equivalent elements. In practice, the used materials, as well as the dimensions, can be any according to the technical requirements.

Claims

1. Embossing and lamination assembly with heated rolls comprising two pairs of steel / rubber rolls between which respectively a first paper ply (11A) and a second paper ply (11B) are fed, in which an upper steel embossing roll (21) is coupled with an upper rubber embossing counter roll (22) and a lower steel embossing roll (31) is coupled with a lower rubber embossing counter roll (32), as well as comprising a glue-distributing assembly (40), provided with an anilox roll (42) and a glue applicator roll (41), placed in contact on a side of said upper steel embossing roll (21), and a coupling roll (13), placed in contact on the opposite side of said upper steel embossing roll (21), comprising heating means (50) associated with at least one of said upper steel embossing roll (21) and said lower steel embossing roll (31), characterized in that it comprises an auxiliary joining device (60) for joining the two paper plies (11A, 11B) placed outgoing from the embossing and lamination assembly and adapted to be selectively activated and deactivated depending on the driving speed of the embossing and lamination assembly.

2. Embossing and lamination assembly according to claim 1, characterized in that said auxiliary joining device of the plies (60) comprises a mechanical ply bonding unit placed outgoing from the embossing and lamination assembly.

3. Embossing and lamination assembly according to claim 2, characterized in that said mechanical ply bonding unit (60) works in contact with a first roll (14') of an outgoing draw station (14).

4. Embossing and lamination assembly according to any one of the preceding claims, characterized in that the lower (32) and / or upper rubber embossing counter roll (22) is provided with an auxiliary motorization (15), selectively activable and deactivable.

5. Embossing and lamination assembly according to any one of the preceding claims, characterized by being provided with an independent motorization (16) for the upper (21) and / or lower (31) steel embossing roll and / or with an independent motorization (17) for the glue applicator roll (41) and / or with an independent motorization (18) for the anilox roll (42) and / or with an independent motorization (19) for the coupling roll (13) .

6. Embossing and lamination assembly according to any one of the preceding claims, characterized in that the glue-distributing assembly (40) is mounted on a slide (43) provided with a linear excursion of at least 100 mm away from the upper steel embossing roll (21).

7. Embossing and lamination assembly according to any one of the preceding claims, characterized in that the coupling roll (13) is provided with an excursion away from the upper steel embossing roll (21) of at least 100 mm.

8. Hot embossing and lamination method actuated on an embossing and lamination assembly object of any one of the preceding claims, characterized in that an auxiliary step of joining the two plies downstream of the coupling roll (13) is performed when the embossing and lamination assembly (10) proceeds at a driving speed lower than a predeterminable speed (x).

9. Method according to claim 8, characterized in that the auxiliary step of joining the two plies is performed by selective activation of the auxiliary joining device of the plies (60).

10. Method according to claim 9, characterized in that the predeterminable driving speed (x) under which the auxiliary joining device of the plies (60) is activated is equal to about 150-200 m / min.

11. Method according to any one of claims 9 or 10, characterized in that the activation and the deactivation of the auxiliary joining device of the plies (60) is performed respectively by closing and opening of a mechanical ply bonding unit placed outgoing from the embossing and lamination assembly.

12. Method according to any one of claims from 8 to 11, characterized in that at stop mode - the upper (22) and / or lower (32) rubber embossing counter roll is detached from the upper (21) and / or lower (31) steel embossing roll and is stopped; - the anilox roll (42) and the glue applicator roll (41) are detached from the upper steel embossing roll (21) and from each other, and the anilox roll (42) is placed in rotation to remain wet by the glue and the glue applicator roll (41) is placed in slow rotation; - the coupling roll (13) is detached from the upper steel embossing roll (21) and placed in slow rotation.

13. Method according to any one of claims from 8 to 12, characterized in that at jog mode: - the upper (22) and / or lower (32) rubber embossing counter roll is detached from the upper (21) and / or lower (31) steel embossing roll and is placed in rotation at jog mode speed; - the anilox roll (42) and the glue applicator roll (41) are detached from the upper steel embossing roll (21) and from each other, and the anilox roll (42) is placed in rotation to remain wet by the glue and the glue applicator roll (41) is placed in slow rotation; - the coupling roll (13) is detached from the upper steel embossing roll (21) and placed in slow rotation.

14. Method according to any one of claims from 8 to 13, characterized in that at driving mode: - the upper (22) and / or lower (32) rubber embossing counter roll is placed under pressure on upper (21) and / or the lower (31) steel embossing roll and dragged in idle rotation therefrom; - the anilox roll (42) is placed in contact with the glue applicator roll (41), the glue applicator roll (41) is placed in contact with the upper steel embossing roll (21), the anilox roll (42) and the glue applicator roll (41) are placed in rotation at the operating speed; - the coupling roll (13) is placed under pressure on the upper steel embossing roll (21) and placed in rotation at the operating speed.

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