Patent Description:
An important production sector of paper articles relates to the production of so-called tissue paper, with which single- or multi-ply web materials, typically wound in rolls, are produced. Tissue paper is used for manufacturing toilet paper, paper towels and similar items.

To achieve several aesthetic and functional features, the tissue paper plies are subjected to embossing processes. This consists in the permanent deformation of the cellulose ply, to create embossing protuberances or protrusions thereon. The embossing serves to achieve technical and functional features of the finished product, and in some cases also for aesthetic reasons.

In some cases, embossing is made to create, on the cellulose ply, limited areas of application of an adhesive, which serves to bond together two or more plies that constitute the finished multi-ply product. By embossing one or more plies, embossed protrusions facing towards an opposite ply, i.e. towards the inside of the multi-ply material, are generated on the ply. The adhesive is applied to the head surface of the embossed protrusions.

In some cases, the embossing must therefore be configured so as to obtain an optimal adhesive distribution, to ensure correct bonding of the plies of a multi-ply web material, obtaining at the same time a soft product, therefore not excessively glued, and avoiding an excessive consumption of adhesive, which in any case constitutes a consumable material that affects the total cost of the finished product.

In some cases, embossing also has the purpose of increasing the overall thickness of the web material and/or of imparting certain features of resistance to crushing.

In some products, embossing has aesthetic and technical/functional purposes. The embossing pattern cannot be chosen as desired exclusively as a function of aesthetic needs, since it also performs technical functions and must respect certain constraints and limits.

In general, one or more plies of a multi-ply cellulose web material of tissue paper are also embossed in order to impart the desired features of softness and liquid absorption capacity, depending on the final use of the cellulose product. Embossing methods and devices are disclosed in <CIT> which involves uniting two plies using a marrying roll having annular protuberances and <CIT>.

There is therefore a continuous search for technical solutions that allow improving the technical-functional aspects of the cellulose product, while imparting an aesthetically pleasing appearance thereto, as well as being pleasant to the touch, to promote and favor the penetration thereof on the market.

According to claim <NUM> a method is provided for producing a multi-ply cellulose tissue paper web material, comprising at least a first ply and a second ply bonded to each other, wherein the first ply is fed between an embossing roller and a first pressure roller, wherein the embossing roller is provided with embossing protuberances distributed according to first annular bands on a lateral surface of the embossing roller, between which second annular bands without embossing protuberances are interposed. The first ply is embossed along longitudinal embossing bands by the embossing protuberances arranged along the first annular bands as a result of co-action of the embossing roller with the pressure roller. Moreover, the ply is simultaneously calendered along longitudinal calendering bands along the second annular bands, as a result of the co-action of the embossing roller with the pressure roller.

As will be shown below, calendering allows obtaining particular benefits in terms of softness of the cellulose material. Embossing may have technical and/or aesthetic functions, and may for example be useful for masking mechanical ply bonding areas between the plies, as described in greater detail below.

In some embodiments, the pressure roller may have a rigid surface, provided with recesses or protuberances which mesh with protuberances of the embossing roller, and smooth annular bands which co-act with the second annular bands of the embossing roller.

However, in preferred embodiments the pressure roller has a yieldable coating, for example and preferably made of elastic material. In this case, the method may provide for the protuberances of the first embossing roller to be pressed against a yielding coating of the first pressure roller, so that the first ply is embossed as a result of the penetration of the embossing protuberances of the first embossing roller into the yielding coating of the first pressure roller. Furthermore, the first ply is calendered along the longitudinal calendering bands by co-action of the first embossing roller with the surface of the yielding coating of the first pressure roller.

The plies are bonded together for example by gluing, for example by performing a further embossing step of the first ply along the calendered longitudinal bands, in order to define areas for glue application.

In other embodiments, the plies may be bonded together by mechanical ply-bonding. As known to those skilled in the art, and as used herein, the term "mechanical ply-bonding" defines a technique for bonding cellulose layers based on the application of a strong pressure on the plies, so as to generate bonding or welding points between the cellulose fibers that form them.

According to claim <NUM> an embossing machine is provided, comprising:.

According claim <NUM> a multi-ply cellulose web material is provided, comprising at least a first ply and a second ply bonded to each other, wherein the first ply comprises longitudinal calendering bands interposed between longitudinal embossing bands. The web material may be wound in rolls, preferably in rolls formed by sheets connected to one another by perforation lines, for example rolls of toilet paper, kitchen paper or other tissue paper products.

Further advantageous features and embodiments of the method, of the web material and of the machine object of the present disclosure are described hereafter with reference to exemplary drawings, and in the appended claims, which form an integral part of the present description.

The invention will be better understood by following the description and the accompanying drawings, which illustrate an exemplifying and non-limiting embodiment of the invention. More particularly, in the drawings:.

Embossing machines for processing plies for the production of a multi-ply web material are described below. The embossing machine has an embossing roller which has annular bands on which embossing protuberances are provided, which are spaced apart from each other by annular zones, without embossing protuberances, which perform a calendering operation on the ply. In this way, a particularly soft cellulose ply is obtained, which can then be subsequently processed to be bonded to one or more cellulose plies of various configurations, by means of gluing, mechanical ply-bonding, or other technique of reciprocal bonding of the plies.

Turning now to the illustrated embodiments, <FIG> schematically shows a first embodiment of an embossing machine <NUM> for the production of an embossed web material made of tissue paper. The machine <NUM> may comprise a first embossing unit <NUM> and a second embossing unit <NUM>.

In the embodiment in <FIG>, the first embossing unit <NUM> comprises a first embossing roller <NUM>, which may be provided with embossing protuberances defining an embossing pattern indicated as a whole with reference numeral <NUM>. The first embossing roller <NUM> is adapted to rotate around a respective rotation axis 11A in the direction indicated by the arrow f11. The first embossing roller <NUM> can be driven in rotation by a respective motor, not shown.

A distributor <NUM> to distribute a liquid substance can be associated to the first embossing roller <NUM>. The distributor can be adapted to distribute a water-based liquid. For example, the distributor <NUM> can be adapted to distribute an ink. As used herein, the term "ink" indicates any liquid substance, preferably water-based, containing a pigment. Preferably, the distributor <NUM> distributes a liquid lacking glue.

With the first embossing roller <NUM> co-acts a first pressure roller <NUM>, adapted to rotate according to the arrow f17 around a respective rotation axis 17A. The first pressure roller <NUM> can be provided with a lateral surface coated with a coating 17R, preferably made of elastically yielding material. The coating 17R can be made for example of rubber, synthetic rubber, or other suitable elastomeric material. The first embossing roller <NUM> and the first pressure roller <NUM> define a first embossing nip <NUM>, through which passes a first path for a ply V1 of web material, for example a ply of tissue paper. The ply V1 can consist of a single layer or of a plurality of layers or plies of cellulose material. For example, the first ply V1 can have grammage between <NUM>/m<NUM> and <NUM>/m<NUM>, preferably between <NUM>/m<NUM> and <NUM>/m<NUM>.

The first pressure roller <NUM> and the first embossing roller <NUM> are pressed against each other so that the embossing protuberances <NUM> penetrate in the elastically yielding coating 17R of the pressure roller <NUM> imparting a permanent deformation to the ply V1 of tissue paper that passes through the first embossing nip <NUM>. The distributor <NUM> is adapted to apply the liquid substance on at least some embossed protrusions formed on the ply V1 by the embossing protuberances <NUM> of the embossing roller <NUM>.

In the embodiment of <FIG>, the second embossing unit <NUM> comprises a second embossing roller <NUM>, provided with embossing protuberances, which define an embossing pattern <NUM>, and adapted to rotate around a rotation axis 23A according to arrow f23. The second embossing roller <NUM> can be driven in rotation by a motor, not shown. To the second embossing roller <NUM> is associated a distributor <NUM> of a liquid substance, for example adapted to apply a glue on embossed protrusions generated by the second embossing roller <NUM> on the first ply of tissue paper V1, as described below.

The second embossing roller <NUM> co-acts with a second pressure roller <NUM>, adapted to rotate around a respective rotation axis 27A according to arrow f27. The second pressure roller <NUM> can be provided with a coating 27R made of an elastically yielding material, similar to the coating 17R of the first pressure roller <NUM>. The second embossing roller <NUM> and the second pressure roller <NUM> form a second embossing nip <NUM> therebetween, through which the path of the first ply V1 extends. In the second embossing nip, the first ply V1 can be subjected to a second embossing operation, i.e. mechanical deformation, by effect of the penetration of the embossing protuberances <NUM> of the second embossing roller <NUM> in the elastically yielding coating 27R of the second pressure roller <NUM>, which is pressed against the second embossing roller <NUM>.

In the embodiment shown in <FIG>, the second embossing unit <NUM> comprises a third embossing roller <NUM>, adapted to rotate according to arrow f31 around a rotation axis31A, by means of a motor, not shown. The third embossing roller <NUM> is provided with embossing protuberances defining an embossing pattern indicated as a whole with reference numeral <NUM>. The third embossing roller <NUM> co-acts with a third pressure roller <NUM>, adapted to rotate around a respective rotation axis35A according to arrow f35. The third pressure roller <NUM> can be provided with an elastically yielding coating 35R, similar to the coating 17R of the first pressure roller <NUM> and to the elastically yielding coating 27R of the second pressure roller <NUM>. Between the third embossing roller <NUM> and the third pressure roller <NUM> an embossing nip <NUM> is defined, whereat the embossing protuberances <NUM> of the third embossing roller <NUM> press against the elastically yielding coating 35R of the third pressure roller <NUM> and penetrate in said coating 35R, so as to emboss a second ply of tissue paper V2, which is fed along a respective feed path. The second ply of tissue paper V2 can have an overall grammage between <NUM>/m<NUM> and <NUM>/m<NUM>, preferably between <NUM>/m<NUM> and <NUM>/m<NUM>. The ply V2 can be single or multiple, i.e. it can in turn be made up of two or more layers or plies.

The path of the second ply of tissue paper V2 extends around the third pressure roller <NUM> and around the third embossing roller <NUM> and from there towards the second embossing roller <NUM>. After being embossed between the third embossing roller <NUM> and the third pressure roller <NUM>, the second ply V2 detaches from the third embossing roller <NUM> and follows the path towards the second embossing roller <NUM>. The path of the ply V1 and the path of the ply V2 join in a laminating nip <NUM>, defined between the second embossing roller <NUM> and a laminating roller <NUM>, adapted to rotate around a respective rotation axis39A according to arrow f39. The laminating roller <NUM> can be coated with an elastically yielding material, for example an elastomer, a natural or synthetic rubber, preferably having greater hardness than the hardness of the coating 17R of the first pressure roller <NUM> and of the coating 27R of the second pressure roller <NUM>. In other embodiments, the laminating roller <NUM> can have a rigid cylindrical surface. The term "rigid" means, in this context, a surface that does not undergo detectable compression deformations at the pressure that is generated between the embossing protuberances <NUM> of the second embossing roller <NUM> and the laminating roller <NUM>.

In some embodiments, the laminating roller <NUM> is mounted idle and driven in rotation by pressure with the embossing roller. In other embodiments, the laminating roller <NUM> can be motorized.

In the laminating nip <NUM>, the second ply V2 is pressed against the first ply V1 to cause the mutual gluing of the plies, as described in more detail below.

<FIG> described below illustrate possible embodiments of the embossing protuberances of the first and second embossing rollers <NUM> and <NUM> and of the respective embossing protuberances generally indicated with reference numeral <NUM> and <NUM> in <FIG>. <FIG> schematically shows a product obtainable with the embossing rollers and respective protuberances shown in <FIG>.

More particularly, <FIG> shows a plan view of a portion of the lateral surface of the first embossing roller <NUM>. In this embodiment, the first embossing roller <NUM> comprises an embossing pattern with annular bands. In some embodiments, the cylindrical lateral surface of the first embossing roller <NUM> comprises annular bands <NUM> of greater width, spaced apart from one another and separated by annular bands <NUM> of smaller width, where width means the dimension of the annular band in the axial direction, i.e. parallel to the rotation axis of the first embossing roller <NUM>.

The annular bands <NUM> may have an embossing pattern of shape substantially different from the annular bands <NUM>. In some embodiments, the width of the annular bands <NUM> is equal to or greater than three times, preferably equal to or greater than four times, the width of the annular bands <NUM>.

In some embodiments, in each annular band <NUM> the embossing roller <NUM> has a smooth surface, free of embossing protuberances. The substantially cylindrical surface is indicated with reference numeral <NUM>.

In the annular bands <NUM>, an embossing pattern is arranged which can be formed by the combination of one or more different series of embossing protuberances.

In the embodiment shown in <FIG>, the embossing pattern of the annular bands <NUM> comprises a first series of embossing protuberances <NUM> and a second series of embossing protuberances <NUM>. Preferably, the embossing protuberances <NUM> of the first series are discrete protuberances, i.e. discontinuous and separate from each other. In the embodiment of <FIG>, the embossing protuberances <NUM> of the first series of embossing protuberances have a truncated-pyramidal shape with an approximately square or rectangular base, but the possibility of using different shapes, for example truncated cones with a circular or elliptical cross section or truncated pyramids with a triangular, pentagonal, hexagonal base, etc., is not excluded. In <FIG>, H57 indicates the height of the protuberances <NUM>.

In some embodiments, the embossing protuberances <NUM> can be linear protuberances, i.e. with a longitudinal dimension much greater than the width thereof, in a plan view, i.e. in a view according to <FIG>. For example, in some embodiments the embossing protuberances <NUM> can define a continuous pattern, meaning that each protuberance extends throughout the entire development of the cylindrical surface of the embossing roller <NUM>. In the embodiment of <FIG>, for example, in each annular band <NUM> the embossing protuberances <NUM> have a continuous fretted pattern, and define a sequence of squares aligned according to the diagonal thereof, extending over the entire circular development of the respective annular band <NUM>. The embossing protuberances <NUM> are distributed inside and outside the squares defined by the embossing protuberances <NUM>.

In some embodiments, as shown in the section in <FIG>, the protuberances <NUM> have a height H59 greater than the height H57 of the protuberances <NUM>.

In some embodiments, the head surface of the protuberances <NUM> may be flat, i.e. smooth. In other currently preferred embodiments, as shown in <FIG>, each embossing protuberance <NUM> has a body <NUM> terminating with a front or head surface, from which small embossing tips <NUM> extend. For example, the size of the tips <NUM> can be such that on the width of each protuberance <NUM> more tips <NUM> can be arranged, for example three tips <NUM> aligned in the direction of the width of the protuberances <NUM>, as shown by way of example in <FIG>.

In some embodiments, the body <NUM> of the protuberances <NUM> has a height H57, and the difference between heights H59 and H57 is given by the height of the tips <NUM>.

In some embodiments, the difference between the height H59 and the height H57 can be between about <NUM> and about <NUM>, preferably between about <NUM> and about <NUM>.

<FIG> shows a section along the line V-V in <FIG>, in which a portion of the cylindrical surface <NUM> and the adjacent protuberances <NUM> are visible. As can be seen in <FIG>, the cylindrical surface <NUM> is lowered, i.e. it has a smaller diameter, with respect to the embossing protuberances <NUM>, for the purposes to be clarified below.

<FIG> shows two dashed and dotted lines T. These lines represent the position in which the web material obtained from the embossing machine <NUM> is cut to produce single finished rolls, as will be described below. In substance, the annular bands <NUM> are positioned, with respect to the final web material, so that the embossing made by them is located near, but not superimposed on, the longitudinal edge of the web material wound in roll. More details on this aspect will be explained below.

<FIG> show a plan view of a portion of the cylindrical surface of the second embossing roller <NUM> and a possible embodiment of the embossing pattern <NUM>. In the illustrated embodiment, the embossing protuberances which define the embossing pattern <NUM> consist of a series of embossing protuberances <NUM>.

The embossing protuberances <NUM> can be protuberances of simple geometric shape, dot-shaped, for example having a truncated pyramidal or truncated-conical shape, as shown in the illustrated example. H61 (<FIG>) indicates the height of the protuberances <NUM>. Preferably, the height H61 of the protuberances <NUM> is equal to or slightly greater than the height of the protuberances of the embossing pattern <NUM> of the first embossing roller <NUM>, i.e. H61 is equal to or greater than H59. In some embodiments, the height H61 is from about <NUM> to about <NUM> greater than H59. Preferably, the height H61 is from about <NUM> to about <NUM> greater than H59.

The protuberances <NUM> are preferably distributed according to annular bands, as shown in <FIG>. More particularly, on the embossing roller <NUM> annular bands <NUM> are provided, in which an embossing pattern is provided, generally indicated with <NUM> in <FIG>, consisting of protuberances <NUM>, interspersed with bands <NUM>, without protuberances <NUM>. The annular bands <NUM> are in phase with the annular bands <NUM> of the first embossing roller <NUM>, in such a way that the embossing protuberances <NUM> make an embossing of the ply V1 in longitudinal bands interposed between longitudinal bands decorated with embossing made by protuberances <NUM> and <NUM>. The bands <NUM> of the embossing roller <NUM> preferably have a smooth cylindrical surface <NUM>.

Since the height H61 of the embossing protuberances <NUM> of the embossing roller <NUM> is greater than the height H57, H59 of the embossing protuberances of the embossing roller <NUM>, the glue distributor <NUM> will apply glue only on the surface of the ply V1, which is on the embossing protuberances <NUM>, in the annular bands <NUM>.

In some embodiments, the embossing protuberances <NUM> can be distributed with a density comprised, for example, between about <NUM> about <NUM> protuberanc-es/cm<NUM>, preferably between about <NUM> and about <NUM> protuberances/cm<NUM> and even more preferably between about <NUM> and about <NUM> protuberances/cm<NUM>.

<FIG> show an embodiment of the embossing protuberances forming the embossing pattern <NUM> of the third embossing roller <NUM>. In some embodiments, the embossing roller <NUM> has an embossing pattern divided into annular bands, similarly to the embossing pattern <NUM> and to the embossing pattern <NUM> of the first embossing roller <NUM> and of the second embossing roller <NUM>. In <FIG>, reference numeral <NUM> indicates first annular bands interspersed with second annular bands <NUM>. The annular bands <NUM> and <NUM> are in phase with the annular bands <NUM> and <NUM>, respectively, of the first embossing roller <NUM>, and with the annular bands <NUM>, <NUM>, respectively, of the second embossing roller <NUM>.

In some embodiments, in the annular bands <NUM> there is provided a respective series of embossing protuberances <NUM>, having a height H75 (<FIG>). The height H75 can be approximately equal to the height H61 of the protuberances <NUM> (<FIG>).

The embossing protuberances <NUM> are preferably dot-shaped, for example with a truncated pyramidal or truncated cone shape and of small dimensions. In some embodiments, the head surfaces <NUM> may have a circular shape with a diameter comprised, for example, between about <NUM> and about <NUM>, preferably between about <NUM> and about <NUM>, for example equal to about <NUM>-<NUM>.

In some embodiments, the head surface <NUM> of the protuberances <NUM> can be between about <NUM><NUM> and <NUM><NUM>.

In some embodiments, the embossing protuberances <NUM> can be distributed with a density comprised, for example, between about <NUM> about <NUM> protuberances/cm<NUM>, preferably between about <NUM> and about <NUM> protuberances/cm<NUM> and even more preferably between about <NUM> and about <NUM> protuberances/cm<NUM>.

A series of embossing protuberances <NUM> is arranged in the annular bands <NUM>. The protuberances <NUM> (<FIG>) can have a height H77, preferably less than the height H75 of the protuberances <NUM>. In some embodiments, the height H77 can be equal to the height H57 of the protuberances <NUM> arranged in the annular bands <NUM> of the embossing roller <NUM>.

In some embodiments, the size of the head surface <NUM> of at least some, and preferably of most of the protuberances <NUM> is greater than the head surface <NUM> of the protuberances <NUM>. For example, the head surface of the embossing protuberances <NUM> can be between about <NUM><NUM> and about <NUM><NUM>, preferably between about <NUM><NUM> and about <NUM><NUM>.

Due to the size of the protuberances of the various embossing rollers <NUM>, <NUM>, <NUM>, and in particular of the heights of these protuberances, the distributor <NUM> applies a colored liquid on the ply V1 at the head surfaces of only the tips <NUM> which have an overall height H59 greater than the protuberances <NUM> and the body <NUM> of the protuberances <NUM>.

Likewise, the glue distributor <NUM> applies the glue C on the ply V1 at the protuberances <NUM>. In the laminating nip <NUM>, the protuberances <NUM> are pressed against the laminating roller <NUM> causing mutual bonding of the plies V1 and V2 due to the glue applied to the ply V1 at the protuberances <NUM>.

<FIG> schematically shows a section of a portion of web material N, which is obtained at the outlet of the laminating nip <NUM>. The section is taken in a transition zone between the two longitudinal bands of the web material N which correspond to the annular bands <NUM>, <NUM>, <NUM> and respectively <NUM>, <NUM>, <NUM>.

The embossed protrusions obtained with the embossing protuberances described above are indicated on the plies V1 and V2. Each embossed protrusion is indicated with the letter "P" followed by a reference which corresponds to the reference numeral indicating the corresponding embossing protuberance of the embossing roller that generated it. Therefore, on the ply V1 in the longitudinal band <NUM>/<NUM>/<NUM> which was processed by the corresponding annular bands <NUM>, <NUM> and <NUM> of the embossing rollers <NUM>, <NUM>, <NUM> there are embossed protrusions P57 and P59. <NUM> formed by the embossing protuberances <NUM> and <NUM>/<NUM> of the embossing roller <NUM>. The head surfaces of the embossed protrusions P59. <NUM> can be decorated with a colored liquid L applied by the distributor <NUM>. Furthermore, again in the longitudinal band <NUM>/<NUM>/<NUM> of the ply V1 there are embossed protrusions P61, formed by the embossing protuberances <NUM> of the embossing roller <NUM>. These embossed protrusions P61 are provided with adhesive C through which the ply V1 is bonded to the ply V2.

In the longitudinal band <NUM>/<NUM>/<NUM>, on the ply V2 there are embossed protrusions P75, formed by the embossing protuberances <NUM> of the embossing roller <NUM>. The embossed protrusions P75 nest randomly between the embossed protrusions P61. The head surfaces of the embossed protrusions P61 are glued by the adhesive C in the spaces between the embossed protrusions P75. In the longitudinal bands <NUM>/<NUM>/<NUM>, the ply V2 has embossed protrusions P77, formed by the embossing protuberances <NUM> of the embossing roller <NUM>.

The embossing patterns described for the embossing rollers <NUM>, <NUM>, <NUM> have a phase in the axial direction (i.e. in the direction of the rotation axis of the embossing rollers), meaning that the annular bands <NUM>, <NUM> and <NUM> are aligned with each other so as to process the same longitudinal bands of the plies V1, V2. Likewise, the annular bands <NUM>, <NUM> and <NUM> are consequently aligned in axial direction and aligned to process the corresponding longitudinal bands of the plies V1, V2. Vice versa, the embossing patterns of the various rollers do not need to be in phase in the tangential direction, i.e. it is not necessary to have a correspondence in the machine direction (feed direction of the plies V1, V2) of the embossing patterns of the various embossing rollers.

The result obtained on the web material N from the embossing patterns described so far with reference to <FIG> is the following. In the longitudinal bands <NUM>; <NUM>; <NUM> of the web material N, a decoration is obtained from the combination of embossed protrusions P59. <NUM>, P59. <NUM> and P57. The head surfaces of the embossed protrusions P59. <NUM> can be decorated with a colored liquid or ink. The decoration can be formed by very small points, the size of the head surfaces of the tips <NUM>. The embossed protrusions P77 generated on the ply V2 by the protuberances <NUM> of the third embossing roller <NUM> are in phase with the embossed protrusions P59. <NUM>, P59. <NUM>, P57 and can provide a support against crushing of the decorative embossed protrusions P59. <NUM>, P59. P57, so that the decoration is not damaged when the web material N is wrapped to form a roll.

The glue C which bonds the two plies V1, V2 is applied according to spots in the bands <NUM>; <NUM>; <NUM>. At the band <NUM>, the ply V1 was calendered between the embossing roller <NUM> and the pressure roller <NUM>. In fact, in the annular bands <NUM> the embossing roller <NUM> is smooth and has a smaller diameter than the diameter of the cylindrical surface on which the head surfaces of the protuberances <NUM> and of the tips <NUM> lie. Consequently, when the pressure roller and the embossing roller <NUM> are pressed against each other at the embossing nip <NUM>, in the areas corresponding to the annular bands <NUM> the protuberances <NUM>, <NUM> penetrate the elastically yielding coating 17R of the pressure roller, causing the embossing, i.e. the permanent deformation of the ply V1, while at the annular bands <NUM> the ply V1 is calendered as a result of the pressure between smooth and opposite cylindrical surfaces of the embossing roller <NUM> and the pressure roller <NUM>.

The longitudinal bands of the ply V1 thus calendered are then embossed by the protuberances <NUM> of the embossing roller <NUM>.

Therefore, the longitudinal bands <NUM>/<NUM>/<NUM> of the web material N are "longitudinal calendering bands", meaning that along said bands at least one ply (V1) has been calendered before being possibly embossed. The calendering operation is performed on the single or multiple ply, which will constitute the outer ply of the finished product. In the embodiments described below, the possibility is also provided that the calendered bands of the ply V1 are not subsequently embossed. The longitudinal bands of calendering are interposed between "longitudinal embossing bands" <NUM>; <NUM>; <NUM>, so called since the large embossing with a predominantly decorative effect, generated by the first embossing roller <NUM>, are made along them.

Overall, the longitudinal calendered bands of the ply V1 are smoother and softer to the touch, attenuating the hardening and stiffening effect caused by the application of adhesive. In this way, an effective bonding of the plies V1, V2 and a product of high softness is obtained.

In different embodiments, not shown, between the first ply V1 and the second ply V2, a third ply may be inserted, which may be smooth or embossed. For example, the third ply can be guided around the roller <NUM> (<FIG>).

<FIG> schematically shows a further embodiment of an embossing machine, indicated as a whole with reference numeral <NUM>, for the production of an embossed multi-ply web material N made of tissue paper. The machine <NUM> comprises elements and components corresponding to those of the machine <NUM> in <FIG>, which are marked with the same reference numerals and which will not be described again.

The main difference between the machine <NUM> and the machine <NUM> consists in that the third embossing roller <NUM> of the second embossing unit <NUM> is placed adjacent to the second embossing roller <NUM>. In this way it is possible, for example, to maintain the phase between the embossing roller <NUM> and the embossing roller <NUM> to couple the plies V1 and V2 in a tip-to-tip arrangement, rather than nested, as shown in <FIG>. As is known to those skilled in the art, in a tip-to-tip arrangement the embossing protuberances of the roller <NUM> are at least in part at the embossing protuberances of the roller <NUM> and correspondingly the embossed protrusions formed on the plies V1, V2 by the embossing rollers <NUM>, <NUM> will be found in tip-to-tip position. In the nip formed between the embossing rollers <NUM> and <NUM>, the embossing protuberances <NUM> of the embossing roller <NUM> and the embossing protuberances <NUM> of the embossing roller <NUM> can be pressed against each other, so as to press the plies V1 and V2 together and cause lamination and bonding thereof. It is therefore possible to eliminate the laminating roller <NUM>.

<FIG> show details of the embossing patterns <NUM>, <NUM>, <NUM> of the embossing rollers <NUM>, <NUM>, <NUM>. Similar to what has been described with reference to <FIG>, also in the embodiment of <FIG> the embossing patterns comprise annular bands with different distributions and shapes of the embossing protuberances. The annular bands of the embossing patterns of the various embossing rollers are aligned with one another, i.e. in phase. In practice, the various annular bands of the different embossing rollers are aligned with each other in the transverse direction, parallel to the axes of rotation of the embossing rollers.

<FIG> show details of the embossing pattern <NUM> of the embossing roller <NUM>. In some embodiments, annular bands are provided on the embossing roller <NUM> which are spaced apart in the direction of the rotation axis 11A and indicated with reference numeral <NUM>. Embossing protuberances <NUM> and <NUM> are distributed in the annular bands <NUM>.

Between two successive embossing bands <NUM> there is provided a band <NUM> without embossing protuberances, in which the embossing roller <NUM> has a smooth cylindrical surface <NUM>.

In the illustrated embodiment, different annular bands <NUM> contain embossing protuberances <NUM> and <NUM> of different shapes. <FIG> illustrate exemplary and non-limiting embodiments of embossing protuberances <NUM> and <NUM>, respectively.

The embossing protuberances <NUM> and <NUM> can have heights H101 and H103. In the example shown, the heights H101 and H103 are equal to each other. In general, the protuberances <NUM> and <NUM> define decorative patterns. The embossing protuberances can have continuous head surfaces, as shown for the embossing protuberance <NUM> in <FIG>, or discontinuous head surfaces, as shown for the embossing protuberance in <FIG>. In practice, the embossing protuberances <NUM> have a body <NUM> with a head surface <NUM>, from which tips <NUM> extend, which define discontinuous front surfaces, i.e. point-like surfaces.

On the areas of the ply V1 embossed by the protuberances <NUM>, <NUM>, the distributor <NUM> can apply a colored liquid. The shape of the protuberances <NUM> is such that the coloring of the ply V1 at these protuberances is discontinuous, that is, point-like or pixel-like, instead of a full color. <FIG> shows two strips or bands with protuberances <NUM> and two strips or bands <NUM> with protuberances <NUM>. This is by way of example only, it being understood that the distribution of the full and pixelated front surface protuberances can be different. For example, only protuberances <NUM> with a full front surface, or only protuberances <NUM> with a pixel-like surface can be provided. Or the protuberances <NUM> and <NUM> can both be present in all the bands <NUM>, with alternate arrangements in any desired sequence. In general, although in the illustrated embodiment each band <NUM> comprises protuberances <NUM> or <NUM> all equal to each other, this is not necessary. For example, decorative protuberances of different shapes may be seen in each band <NUM>.

The height H101 and H103 of the protuberances <NUM> and <NUM> can be for example between about <NUM> and about <NUM>, preferably between about <NUM> and about <NUM>, for example around about <NUM>- <NUM>.

In general, the height of the protuberances <NUM> and <NUM> is sufficiently limited to almost completely penetrate the elastically yielding coating 17R of the pressure roller <NUM>. In this way, in the bands <NUM> without embossing protuberances the ply V1 is calendered between the smooth cylindrical surface <NUM> of the embossing roller <NUM> and the smooth cylindrical surface of the coating 17R of the pressure roller <NUM>. Calendering contributes to obtaining a particularly smooth cellulose material, as described above. This is particularly appreciated when the user perceives it on the external side of the product.

The embossing roller <NUM> can have an embossing pattern <NUM> consisting of protuberances of simple geometric non-decorative shape, for example truncated cone or truncated pyramidal, therefore substantially dot-shaped. Preferably, the embossing roller <NUM> has annular bands provided with micro-embossing protuberances, indicated with reference numeral <NUM> in <FIG> is an enlarged section along the line XIX-XIX of <FIG>.

As shown in <FIG>, the protuberances <NUM> are distributed in annular bands <NUM>, spaced apart from each other by annular bands <NUM> without embossing protuberances. The annular bands <NUM> are aligned in the machine direction, that is, in the direction of advancement of the ply V1, with the annular bands <NUM>, while the annular bands <NUM> without protuberances <NUM> are aligned in the machine direction with the annular bands <NUM>. In this way, the protuberances <NUM> emboss the ply V1 in the bands that have been previously calendered between the embossing roller <NUM> and the pressure roller <NUM>, while the longitudinal bands embossed by the embossing protuberances <NUM>, <NUM> remain intact and do not undergo any embossing process in the embossing nip <NUM>.

In some embodiments, the embossing protuberances <NUM> may have an approximately truncated conical or truncated pyramidal shape. The protuberances <NUM> can have a height H105, preferably greater than the height H101 and the height H103 of the protuberances <NUM> and <NUM> of the embossing roller <NUM>. In this way, the crushing of the decorations obtained on the ply V1 by means of the embossing roller <NUM> is avoided. For example, the protuberances <NUM> may have a height from about <NUM> to about <NUM> greater than the heights H101 and H103, preferably from about <NUM> to about <NUM> and more preferably about <NUM> greater than the height H101 and at height H103.

The protuberances <NUM> may have a density between about <NUM> and about <NUM>, preferably between about <NUM> and about <NUM> protuberances/cm<NUM> in the bands <NUM>.

The glue distributor <NUM> is arranged to apply glue on the deformed and embossed portions of ply V1 from the embossing protuberances <NUM>.

The third embossing roller <NUM> can have a pattern of embossing protuberances <NUM> configured as shown in <FIG>. Also, in this case the embossing pattern <NUM> is according to annular bands. In annular bands <NUM> there are embossing protuberances <NUM> of greater dimensions than the embossing protuberances <NUM> arranged inside annular bands <NUM>. The annular bands <NUM> are aligned with the annular bands <NUM> of the embossing roller <NUM> and with the annular bands <NUM> of the embossing roller <NUM>. The annular bands <NUM> are, on the other hand, aligned with the annular bands <NUM> of the embossing roller <NUM> and with the annular bands <NUM> of the embossing roller <NUM>.

In some embodiments, the protuberances <NUM> arranged in the annular bands <NUM> have a large-sized head surface, i.e. for example, with an area ranging from about <NUM> to about <NUM><NUM>. They can be of simple geometric shape, for example truncated cone or truncated-pyramidal as shown in the figure. The base of the truncated-pyramidal pyramids may be hexagonal, as illustrated by way of example, or of another polygonal shape, for example square, rectangular, triangular, pentagonal, octagonal, etc..

Advantageously, the head surface and the pitch between the protuberances <NUM> is such that the ply V2 embossed by these protuberances <NUM> forms embossed protrusions, facing towards the inside of the resulting web material N, which form a support for the embossed protrusions obtained from the protuberances <NUM>, <NUM>, without the need for a phasing, that is, of a synchronization in the tangential direction, i.e. in the machine direction, of the embossing rollers.

The protuberances <NUM> may have a small height H107, so as not to increase the thickness of the ply V2 excessively. For example, the height H107 can be between about <NUM> and about <NUM>, preferably between about <NUM> and <NUM>, even more preferably between about <NUM> and <NUM>.

The protuberances <NUM> can be dot-shaped protuberances, having a simple geometric shape, for example a truncated pyramidal or truncated-conical shape. The height H109 of the protuberances <NUM> can be between about <NUM> and about <NUM>, preferably between about <NUM> and about <NUM>, even more preferably between about <NUM> and <NUM>. In some embodiments, the height H109 can be substantially equal to the height H105 of the protuberances <NUM>.

In some embodiments, the distribution density of the protuberances <NUM> may be approximately equal to the density of the protuberances <NUM>. For example, the protuberances <NUM> may have a density between about <NUM> and about <NUM>, preferably between about <NUM> and about <NUM> protuberances/cm<NUM> in the bands <NUM>.

In advantageous embodiments, the protuberances <NUM> and the protuberances <NUM> are arranged according to a tip-to-tip arrangement, so that the adhesive C applied to the ply V1 at the protuberances <NUM> glues the ply V1 against areas of the ply V2 embossed by the embossing protuberances <NUM>. In the nip between the embossing rollers <NUM> and <NUM> there can be a rolling pressure between the protuberances <NUM> and the protuberances <NUM>, to obtain mutual adhesion of the two plies V1, V2.

<FIG> shows a schematic section of a portion of web material N obtained by the machine <NUM>. The plies V1, V2 have embossed protrusions, each of which is marked in <FIG> with the letter "P" followed by a number corresponding to the reference numeral indicating the embossing protuberance of the respective embossing roller which has formed the respective embossed protrusion.

In the illustrated example, the ply V1 has, in longitudinal bands marked <NUM>/<NUM>/<NUM>, and corresponding to the annular bands <NUM>, <NUM> and <NUM>, embossed protrusions P103 with frontal tips or pixels P103. <NUM>, on which a dye can be applied by the distributor <NUM>. In front of the embossed protrusions P103, the ply V2 has embossed protrusions P107 formed by the embossing protuberances <NUM> and which form a support for the embossed protrusions P103. The embossed protrusions P103, P103. <NUM> and P107 form longitudinal decorations.

In the longitudinal bands <NUM>/<NUM>/<NUM>, which correspond to the annular bands <NUM>, <NUM> and <NUM>, the ply V1 has embossed protrusions P105 formed by the embossing protuberances <NUM>, which are glued at the head by means of glue C to the head of embossing protrusions P109 formed in the same annular band in the ply V2 by the embossing protuberances P109.

The longitudinal bands <NUM>, <NUM>, <NUM> are particularly soft and absorbent thanks on the one hand to the calendering performed by the first embossing roller <NUM> and the first pressure roller <NUM>, and on the other hand to the micro-embossing performed by the embossing protuberances <NUM> of the second embossing roller <NUM>.

In some embodiments, a third intermediate ply can be provided and inserted between the plies V1 and V2. The third ply can be smooth. In other embodiments, the third ply can be embossed together with the ply V1, that is, it can follow the same path thereof. In other embodiments, the third ply can be embossed together with the second ply V2. In still other embodiments, the third ply can be micro-embossed independently of the plies V1 and V2, for example in a further embossing unit indicated with a broken line in <FIG>, where the third ply is indicated with V3.

In other embodiments, the third embossing roller <NUM> can be provided with micro-embossing protuberances <NUM> on the entire surface, instead of only in the annular bands <NUM>, eliminating the protuberances <NUM> of hexagonal shape (in the example). In this case, the micro-embossing formed by the protuberances <NUM> can define the areas of mutual bonding between the plies V1 and V2, at the protuberances <NUM>, and at the same time it can form support areas for the decorative embossed protrusions P103, formed by the protuberances <NUM> or similarly by the protuberances <NUM> (<FIG>).

<FIG> shows a diagram of a further embossing machine <NUM> for the production of a multi-ply cellulose web material N formed by embossed and bonded plies V1, V2. Same numbers indicate parts identical or equivalent to those illustrated in the above embodiments. In this embodiment, the embossing machine <NUM> comprises a first embossing unit <NUM>, which can be made like the embossing unit <NUM> in <FIG> or <FIG>.

The embossing machine <NUM> in <FIG> has a second embossing unit <NUM> which is provided only with an embossing roller <NUM> with embossing protuberances generally indicated with reference numeral <NUM>, co-acting with a pressure roller <NUM>, while the embossing roller <NUM> and relative members coa-acting therewith are lacking.

In some embodiments of the embossing machine <NUM>, the plies V1 and V2 are bonded together by mechanical ply-bonding rather than by gluing. For this purpose, a series of mechanical ply-bonding wheels <NUM> can be provided, which are pressed against the embossing roller <NUM>. The mechanical ply-bonding wheels <NUM> can have a smooth edge and can co-act with embossing protuberances arranged according to bands on the embossing roller <NUM>. For example, the embossing roller <NUM> can be provided with an embossing pattern as shown in <FIG> or preferably as shown in <FIG>. The mechanical ply-bonding wheels <NUM> can be arranged at the bands <NUM>, so as to co-act with the head surfaces of the embossing protuberances <NUM> or <NUM> and/or <NUM> described above. Preferably, the embossing protuberances of the embossing roller <NUM> have, in this case, small-sized tips which project from the head of larger-sized protuberances, as shown specifically in <FIG> for the protuberances <NUM>, and in <FIG> for the protuberances <NUM>. In this way, a high localized pressure is obtained, which facilitates bonding by mechanical pressure. The embossing wheels <NUM> can have a smooth cylindrical peripheral surface.

When the embossing machine <NUM> is provided with a distributor <NUM> of a liquid colored or colorless substance, this can favor mechanical bonding, thanks to the water applied to the ply V1 in the areas on which the pressure by the mechanical ply-bonding wheels <NUM> is applied.

With the machine <NUM> shown in <FIG>, a web material N is obtained in which the mechanical ply-bonding lines are generated at the decorations obtained on the ply V1 by the protuberances arranged according to bands on the embossing roller <NUM>. These protuberances, possibly in combination with corresponding embossing protuberances <NUM> of the roller <NUM> as shown in <FIG> or <NUM> of <FIG>, serve to mask and conceal the mechanical deformations generated by mechanical ply-bonding. In practice, therefore, the finished product does not have, as is the case with web materials bonded by mechanical ply-bonding of the prior art, bulges in the longitudinal bands in which the mechanical ply-bonding is carried out.

In this way, a higher quality, aesthetically improved product is obtained, which also has a more uniform thickness, with consequent technical advantages in the subsequent processing steps.

In the embodiment shown in <FIG> the ply V2 is embossed, for example with a continuous micro-embossing or with bands as described for the ply V2 in the above embodiments. In other embodiments, vice versa, the ply V2 can be smooth. For this purpose, it is possible, for example, to provide that the embossing roller <NUM> remains distanced from the pressure roller <NUM>, or that the unit consisting of the rollers <NUM> and <NUM> is not present.

While in <FIG> mechanical ply-bonding is performed with preferably smooth mechanical ply-bonding wheels, which act against the embossing roller <NUM>, in other embodiments an independent mechanical ply-bonding unit can be provided, separate from the embossing unit <NUM> and therefore from the embossing roller <NUM>. <FIG> shows an embodiment of this type. Equal numbers indicate parts that are identical or equivalent to those already described with reference to the above figures, and in particular to <FIG>. In the diagram in <FIG>, the machine is generally indicated with reference numeral <NUM>, the mechanical ply-bonding wheels are indicated with reference numeral <NUM> and co-act with a counter-roller <NUM>. The counter-roller <NUM> and the mechanical ply-bonding wheels <NUM> are separated from the embossing roller <NUM>, in the sense that they are not in contact therewith. The embossing roller <NUM> can be configured as in one of the embodiments described so far. The embossed ply V1 in the embossing nip <NUM> between the embossing roller <NUM> and the pressure roller <NUM> is detached from the embossing roller <NUM> and fed into the mechanical ply-bonding nip formed between the mechanical ply-bonding wheels <NUM> and the counter-roller <NUM>. Into this nip also the ply V2 can be fed, which can be embossed in the embossing nip <NUM>, or smooth. One or the other or both plies V1, V2 can be formed by a single layer or by several superposed layers.

The mechanical ply-bonding wheels <NUM> can have a smooth edge, or a knurled edge, or can be provided with small protuberances, so as to reduce the area of contact with the counter-roller <NUM>. In this way, a higher pressure is obtained, with the same thrust between mechanical ply-bonding wheels <NUM> and counter-roller <NUM>, and therefore a more effective bonding between the plies.

In <FIG> the colored liquid distributor <NUM> has been omitted, but it is to be understood that a distributor <NUM> can be provided in the embossing machine <NUM> as well, for example to generate a colored decoration and/or to humidify the cellulose material which forms the ply V1 and therefore improve the bond obtained by mechanical pressure.

<FIG> shows a further embodiment of an embossing machine, indicated as a whole with reference numeral <NUM>. The structure of this machine is similar to that of the embossing machine <NUM> in <FIG>. Equal numbers indicate parts identical or corresponding to those already described. In particular, the embossing rollers of the two embossing units <NUM>, <NUM> can be configured as described with reference to <FIG>, or alternatively as described with reference to <FIG>.

The main difference between the embossing machine in <FIG> and the embossing machines in <FIG> and <FIG> consists in that in <FIG>, bonding between the plies V1, V2 is performed by means of a mechanical ply-bonding unit comprising mechanical ply-bonding wheels <NUM> co-acting with a counter-roller <NUM>. The glue dispenser can therefore be omitted. The ply V1 can thus in this way be embossed in the embossing nip <NUM> without receiving adhesive, but solely to impart other technical-functional features to the product, for example a greater thickness and/or a greater absorption capacity. The plies V1 and V2 are then mechanically ply-bonded by the ply-bonding wheels <NUM> and by the counter-roller <NUM>, which can preferably be made as already described with reference to the mechanical ply-bonding unit <NUM>, <NUM> in <FIG>.

In all the embodiment of <FIG>, the embossing roller <NUM> and the pressure roller <NUM> generate on the ply V1 embossed bands (usually narrower) separated by bands (usually wider than the previous ones) in which the cellulose material of the ply V1 is calendered between a smooth cylindrical surface of the embossing roller <NUM> and the smooth cylindrical surface of the coating 17R of the pressure roller <NUM>.

<FIG> shows a schematic representation of a roll R made of wound web material N. A portion of the web material is unwound to show how it is formed by sheets F connected to one another along perforation lines LT, by a perforating unit known per se. B1 and B2 indicate the longitudinal edges of the web material N obtained by cutting a log by means of a log saw for dividing the log into individual rolls R. As mentioned above, the cut can be made at the dotted lines T shown in <FIG> and <FIG>. In this way, the bands <NUM>, <NUM>, <NUM> decorated by the protuberances of the embossing roller <NUM> are located at a certain distance from the edges B1, B2. If the web material N is obtained by gluing the plies V1, V2 (and possibly other plies V3, etc. which constitute it), the adhesive can be applied on embossing protuberances generated by the embossing roller <NUM> up to the edges B1, B2, and up to the perforation lines LT, so that the plies are effectively bonded to one another along the edges of each sheet F. If, on the other hand, the plies are bonded together by mechanical ply-bonding, the ply junction area can be a certain distance from the edges B1, B2 as it happens in the products of the prior art, but (contrary to the known products), the mechanical ply bonding lines do not negatively influence the aesthetic and functional features of the finished article. In all cases, the outer ply is the calendered one.

<FIG> show summary and illustrative block diagrams of methods described herein.

Claim 1:
A method for producing a multi-ply cellulose tissue paper web material, comprising at least a first ply (V1) and a second ply (V2) bonded to each other, wherein the first ply (V1) is fed between an embossing roller (<NUM>) and a first pressure roller (<NUM>), wherein the embossing roller (<NUM>) is provided with embossing protuberances (<NUM>; <NUM>; <NUM>; <NUM>) distributed according to first annular bands on a lateral surface of the embossing roller (<NUM>), between which there are interposed second annular bands without embossing protuberances; and wherein the first ply (V1) is embossed along longitudinal embossing bands (<NUM>; <NUM>), and calendered along longitudinal calendering bands (<NUM>; <NUM>), as a result of co-action of the embossing roller (<NUM>) with the pressure roller (<NUM>); and wherein after calendering and embossing, the first ply (V1) and the second ply (V2) are bonded to one another.