EMBOSSED MULTILAYERED CELLULOSE PRODUCT AND MEANS FOR THE PRODUCTION THEREOF

Abstract

The cellulose product comprises at least a first ply of embossed cellulose material and a second ply of embossed cellulose material, glued together. The first ply comprises: a first series of embossing protuberances with a first height (H′1) and a top surface to which a glue is applied which bonds the first ply and the second ply to one another; a second series of micro-embossing protuberances with a second height (H′2) lower than the first height (H′1); a third series of micro-embossing protuberances with a third height (H′3) lower than the second height (H′2). The protuberances of the first series are distributed over areas of the first ply, where the micro-embossing protuberances of the second series and the micro-embossing protuberances of the third series are absent.

Claims

1. A cellulose product comprising at least a first ply of embossed cellulose material and a second ply of embossed cellulose material, glued together, wherein the first ply comprises: a first series of embossing protuberances with a first height and a top surface to which a glue is applied which bonds the first ply and the second ply to one another; a second series of micro-embossing protuberances with a second height lower than the first height; a third series of micro-embossing protuberances with a third height lower than the second height; wherein the protuberances of the first series are distributed over areas of the first ply, where the micro-embossing protuberances of the second series and the micro-embossing protuberances of the third series are absent.

2. Cellulose product according to claim 1, wherein the second ply comprises: a fourth series of embossing protuberances with a fourth height; a fifth series of micro-embossing protuberances with a fifth height lower than the fourth height; a sixth series of micro-embossing protuberances with a sixth height lower than the fifth height; wherein the protuberances of the fourth series are distributed over areas of the second ply, where the micro-embossing protuberances of the fifth series and the micro-embossing protuberances of the sixth series are absent.

3. Cellulose product according to claim 2, wherein the first protuberances and the fourth protuberances are nested together.

4. Product according to one or more of the previous claims, wherein the protuberances of the second series and the protuberances of the third series are distributed alternately.

5. Product according to claim 4, wherein the protuberances of the second series and the protuberances of the third series are distributed along lines preferably parallel to one another, wherein along a first line protuberances of one of said second series and third series are placed, and along a second line, adjacent to the first line, protuberances of the other of said second series and third series are placed.

6. Product according to claim 2, wherein the protuberances of the fifth series and the protuberances of the sixth series are distributed alternately.

7. Product according to claim 6, wherein the protuberances of the fifth series and the protuberances of the sixth series are distributed along lines preferably parallel to one another, wherein along a first line protuberances of one of said fifth series and sixth series are placed, and along a second line, adjacent to the first line, protuberances of the other of said fifth series and sixth series are placed.

8. Product according to one or more of the previous claims, wherein the first height is between around 1.1 mm and around 2 mm.

9. Product according to one or more of the previous claims, wherein the second height is between around 0.25 mm and around 0.35 mm lower than the first height.

10. Product according to one or more of the previous claims, wherein said third height is between around 0.1 mm and around 0.3 mm lower than the second height.

11. Product according to one or more of the previous claims, wherein the fourth height (H′.sub.4) is between around 1.1 mm and around 2 mm.

12. Product according to one or more of the previous claims, wherein the fifth height is between around 0.25 mm and around 0.35 mm lower than the fourth height.

13. Product according to one or more of the previous claims, wherein said sixth height is between around 0.1 mm and around 0.3 mm lower than the fifth height.

14. An embossing roller for the production of a cellulose product, comprising: a first series of embossing protuberances with a first height and a top surface; a second series of micro-embossing protuberances with a second height lower than the first height; a third series of micro-embossing protuberances with a third height lower than the second height; wherein the protuberances of the first series are distributed over areas of the first ply, where the micro-embossing protuberances of the second series and the micro-embossing protuberances of the third series are absent.

15. Embossing roller according to claim 14, wherein the protuberances of the second series and the protuberances of the third series are distributed alternately.

16. Embossing roller according to claim 15, wherein the protuberances of the second series and the protuberances of the third series are distributed along lines preferably parallel to one another, wherein along a first line protuberances of one of said second series and third series are placed, and along a second line, adjacent to the first line, protuberances of the other of said second series and third series are placed.

17. Embossing roller according to one or more of the claims from 14 to 16, wherein the first height is between around 1.1 m and between 2 mm.

18. Embossing roller according to one or more of claims 14 to 17, wherein the second height is between around 0.25 and around 0.35 mm lower than the first height.

19. Embossing roller according to one or more of claims 14 to 18, wherein said third height is between around 0.1 mm and around 0.3 mm lower than the second height.

20. An embossing unit comprising two embossing rollers according to one or more of claims 14 to 19, each cooperating with a respective pressure roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention will be better understood by following the description and the accompanying drawing, which shows non-limiting practical embodiments of the invention. More particularly, in the drawing:

[0020] FIGS. 1 and 2 show diagrams of embossing-laminating devices in which the invention may be embodied;

[0021] FIGS. 1A, 1B show enlargements of details in FIG. 1;

[0022] FIG. 3 shows a plan development of a portion of the embossing surface of an embossing roller;

[0023] FIGS. 4 and 5 show sections according to IV-IV and VV in FIG. 3;

[0024] FIGS. 6 and 7 show schematic sections of an embossed web material.

DETAILED DESCRIPTION OF METHODS OF EMBODIMENT OF THE INVENTION

[0025] The following detailed description of exemplary embodiments refers to the accompanying drawings. Same reference numerals in different drawings identify the same or similar elements. Also, the drawings are not necessarily to scale. The following detailed description does not limit the invention. Rather, the scope of the invention is defined by the appended claims.

[0026] The reference throughout the specification to “one embodiment” or “the embodiment” or “some embodiments” means that a particular feature, structure or element described in relation to an embodiment is included in at least one embodiment of the object described. Therefore, the phrase “in one embodiment” or “in the embodiment” or “in some embodiments” in various points along the description does not necessarily refer to the same embodiment or to the same embodiments. Furthermore, the particular features, structures or elements can be combined in any suitable manner in one or more embodiments.

[0027] FIG. 1 shows a schematic side view of an embossing-laminating device 1 of the tip-to-tip type. The embossing-laminating device 1 comprises a first embossing roller 3, rotating around a rotation axis 3A, and a second embossing roller 5, rotating around a rotation axis 5A substantially parallel to the rotation axis 3A of the first embossing roller 3. A lamination nip 6 is defined between the first embossing roller 3 and the second embossing roller 5.

[0028] The first embossing roller 3 cooperates with a first pressure roller 7 rotating about an axis which may be approximately parallel to the rotation axis of the embossing roller 3. The second embossing roller 5 cooperates with a second pressure roller 9, whose rotation axis may be approximately parallel to the rotation axis of the second embossing roller 5. A first embossing nip 11 is defined between the first embossing roller 3 and the first pressure roller 7. A second embossing nip 13 is defined between the second embossing roller 5 and the second pressure roller 9.

[0029] The first pressure roller 7 may be coated with a coating layer 7R of yielding material, preferably of an elastically yielding material, such as rubber. Likewise, the second embossing roller 9 may be coated with a coating layer 9R of yielding material, preferably an elastically yielding material.

[0030] The first embossing roller 3 and the second embossing roller 5 may be provided with a plurality of embossing protuberances, generically indicated with 3P and 5P, respectively, and visible in the schematic enlargements in FIGS. 1A and 1B. Exemplary embodiments of the embossing protuberances 3P and 5P will be described in greater detail hereinafter.

[0031] In some embodiments, the first embossing roller 3 cooperates with a glue dispenser 15.

[0032] Two paths are defined in the embossing-laminating device 1 for a first ply V1 arid a second ply V2 of web material, such as plies of cellulose fibers, in particular plies of tissue paper. The first path for the first ply of web material V1 extends around the first pressure roller 7, extends through the embossing nip 11 and extends around the first embossing roller 3 by passing between the latter and the glue dispenser 15. The second path for the second ply of web material V2 extends around the second pressure roller 9, through the embossing nip 13 and develops around the second embossing roller 5. In the embossing nips 11 and 13, the two plies V1 and V2 are embossed by the effect of the pressure between the respective embossing roller and the respective pressure roller, the embossing protuberances 3P and 5P penetrating into the yielding coating 7R and 9R of the respective pressure roller, generating embossed protuberances in plies V1 and V2.

[0033] In the lamination nip 6 between the two embossing rollers 3 and 5, the two paths of plies V1 and V2 join so that plies V1 and V2 are bonded by means of the glue that is applied by the glue dispenser 15 on the embossed protuberances on the first ply V1. In the lamination nip 6, at least some of the embossing protuberances 3P oppose respective embossing protuberances 5P. The pressure exerted between protuberances 3P and 5P causes gluing of the two plies V1 and V2, which in combination form a multi-ply web material N.

[0034] FIG. 2 shows a schematic side view of an embossing-laminating unit of the nested type. Same numbers indicate parts identical or equivalent to those of the embodiment in FIG. 1. These parts are not described again. In this embodiment, the two plies V1 and V2 are not mutually laminated in nip 6 but in a nip 10 formed between the embossing roller 3 and a laminating roller 12, which may be of steel or other rigid material, or coated with an elastically yielding material, preferably of greater hardness than the coating of the pressure rollers 7 and 9.

[0035] FIG. 3 shows a development of a portion of a ply V1 or V2 embossed with the embossing-laminating device 1 in FIG. 1 or FIG. 2. Since the embossed pattern obtained on the cellulose ply V1 or V2 corresponds to the embossing pattern, that is, to the arrangement of the embossing protuberances of the embossing roller 3 or 7, the representation in FIG. 3 can also be seen as the plan development of a portion of the cylindrical side surface of the embossing roller 3 or the embossing roller 7 of one of the embossing-laminating devices 1 in FIG. 1 or 2.

[0036] FIG. 3 shows an embossing pattern including a first series of embossing protuberances P1, a second series of embossing protuberances P2 and a third series of embossing protuberances P3. In this embodiment, the embossing protuberances P1 of the first series are larger in size than the embossing protuberances P2 and P3 and therefore can be easily distinguished from the latter. Only for easier differentiation between protuberances P2 of the second series and protuberances P3 of the third series, in FIG. 3 protuberances P2 are indicated with contour lines of different thicknesses.

[0037] FIGS. 4 and 5 show local enlarged sectional views of the embossing protuberances of a corresponding embossing roller, according to lines IV-VI and V-V, respectively, in FIG. 3. Hereinafter, “embossing protuberances” indicates both the protuberances formed on the embossing roller and the protuberances generated on a ply by the embossing roller. The patterns of the embossing protuberances on the roller and on the ply correspond to each other.

[0038] As it can be seen in particular in the sections in FIGS. 4 and 5, the embossing protuberances P1 of the first series have a height H.sub.1, while the embossing protuberances P2 and P3 of the second and third series have heights H.sub.2 and H.sub.3, respectively. In embodiments described herein, heights H.sub.1, H.sub.2 and H.sub.3 are different from one another and are in the following relationship:

H.sub.1>H.sub.2>H.sub.3

that is, protuberances P1 are the highest, while protuberances P3 are the lowest.

[0039] Each protuberance P1, P2, P3 has a base and a head surface T1, T2, T3, as well as respective sides F1, F2, F3. In the embodiment shown, the embossing protuberances P1 form a decorative pattern. Each protuberance has a substantially elliptical cross section. It is, however, a mere exemplifying representation, because the shape of protuberances P1 may be different, for example protuberances P1 may have an elongated shape, with a much greater longitudinal dimension, for example ten times or more than ten times greater than the transverse dimension.

[0040] In the embodiment shown, the embossing protuberances P2 and P3 of the second series form a background embossing, or a micro-embossing. In the example shown, protuberances P2 and P3 preferably have a cross section with the same shape, for example elliptical. In other embodiments, the cross section of protuberances P2, P3 may be different, for example circular or polygonal, either regular or irregular. In some embodiments, the shape of protuberances P2 may be different than the shape of protuberances P3. For example, protuberances P2 may have a circular cross section and protuberances P3 may have an elliptical cross section.

[0041] In the embodiment shown in FIG. 3, the embossing protuberances P2 of the second series and the embossing protuberances P3 of the second series are arranged according to respective alignments, indicated by lines L1 and L2. Lines L1 and L2 in the embossed product can be straight lines, which on the embossing roller correspond to helical lines developing about the rotation axis of the embossing roller.

[0042] In some embodiments, lines L1 and L2 may be mutually inclined for example by 90°, as shown in the figure.

[0043] In some particularly advantageous embodiments, the embossing protuberances P2 and P3 are arranged in mutually alternate alignments L1. As can be clearly understood from FIG. 3, for example, on a line L1 all embossing protuberances P3 belong to the third series and have a height H.sub.3. The embossing protuberances on the adjacent lines L1 are embossing protuberances P2 of the second series and have a height H.sub.2. A similar alternating distribution may be provided along lines L2.

[0044] In advantageous embodiments, the embossing protuberances P2 of the second series and the embossing protuberances P3 of the third series may be distributed along lines L1 and L2 at a substantially even pitch.

[0045] Advantageously, in some embodiments, the embossing protuberances P2 of the second series and the embossing protuberances P3 of the third series may be distributed along lines L1 and L2 according to a pattern with areas devoid of such embossing protuberances P2 and P3. In some embodiments, the embossing pattern may have areas devoid of embossing protuberances P2 of the second series and embossing protuberances P3 of the third series around protuberances P1 of the first series. In the exemplary embodiment in FIG. 3, for example, there are areas indicated with A devoid of embossing protuberances P2, P3 and in which the embossing protuberances P1 of the first series are distributed.

[0046] In this way, the effect of giving greater prominence to the pattern formed by the embossing protuberances P1 of the first series is obtained.

[0047] FIG. 6 shows a simplified schematic cross section of a portion of a multi-ply web material N, comprising a first ply V1 and a second ply V2. In the example shown, ply V2 is embossed with embossing protuberances P4 nested between protuberances P1. In some embodiments, protuberances P4 of ply V2 may be nested in areas of ply V1 devoid of embossing protuberances P2 and P3, that is, in areas corresponding to the areas or portions indicated with A of the embossing pattern of the embossing roller. H′.sub.1, H′.sub.2 and H′.sub.3 indicate the heights of the embossing protuberances P1, P2, P3 formed in the cellulose ply V1. These heights are different from one another and are in the following relationship with one another:

H′.sub.1>H′.sub.2>H′.sub.3

[0048] These heights may be equal to heights H.sub.1, H.sub.2 and H.sub.3 of the corresponding embossing protuberances formed on the respective embossing roller. This, however, is not necessary. In practice, the heights of the protuberances embossed on the ply may be smaller than the heights of the corresponding embossing protuberances on the roller, since a mutual pressure may be exerted between the rollers in the embossing nip between the embossing roller and the pressure roller such that the elastically yielding coating of the pressure roller does not penetrate completely into the cavities between the embossing protuberances of the embossing roller.

[0049] In other embodiments, ply V2 may also be provided with secondary embossing protuberances, of smaller height, preferably of different heights. FIG. 7 shows a simplified and enlarged cross-sectional view of a web material N of this type. Ply V2 is provided with embossing protuberances P4 of a fourth series of protuberances and with protuberances P5 and P6 of a fifth series and a sixth series of embossing protuberances, respectively. The relationship between the heights (herein indicated with H′.sub.4, H′.sub.5 and H′.sub.6) of the protuberances embossed on ply V2 may be

H′.sub.4>H′.sub.5>H′.sub.6

[0050] In the example in FIG. 7, the two plies V1 and V2 are still arranged in a nested configuration, that is, with protuberances P4 inserted (nested) between protuberances P1. In other embodiments, both in the case of ply V2 with embossing protuberances P4 and in the case of ply V2 with embossing protuberances P4, P5 and P6 in combination, the bonding between the plies can be of the tip-to-tip type, with the heads of at least some of protuberances P1 at the heads of protuberances P4.

[0051] The embossing protuberances formed on ply V1 and/or on ply V2 develop from the base material, indicated with Vb1 and Vb2 (FIGS. 6 and 7) towards the inside of the web material N.

[0052] The two plies V1 and V2 may be bonded together by gluing using a glue C. This can be distributed on the head surfaces, facing towards the inside of the web material N, of the embossing protuberances P1 and/or P4 of the first series of protuberances, or on at least some of them, as shown in FIGS. 6 and 7.

[0053] The background embossing or micro-embossing formed by protuberances P2 and P3 of different heights imparts a consistency, an appearance and a tactile feature to the embossed cellulose material which imitates and resembles that of the tissue paper formed by means of TAD (Through Air Drier) systems, without the plant and energy consumption costs typical of these known systems. Features are thus obtained which are of great aesthetic and functional value at substantially reduced costs.

[0054] In some embodiments, the first height H.sub.1 or H′.sub.1 of the first protuberances of the embossing roller or of the embossed ply may be between about 1.1 and about 2 mm, while the second height H.sub.2 or H′.sub.2 may be from about 0.25 to about 0.35 mm lower than the first height. In this way, the glue distributed on the heads of the first protuberances, for example via the glue dispensing unit 15, is not applied on the embossing protuberances of the second series and of the third series. In some embodiments, the third height H.sub.3 or H′.sub.3 is from about 0.1 mm to about 0.3 mm lower than the second height.