ITFI20060100A1 - METHOD AND PLANT FOR THE TRANSFORMATION OF TISSUE PAPER WITH APPLICATION OF DAMP-RESISTANT AGENTS - Google Patents

Abstract

A method and system are described in which at least one wet strength agent, such as wet strength resin, is added to one or more plies of tissue paper or other cellulose product during the converting process.

Description

"METHOD AND PLANT FOR THE TRANSFORMATION OF TIS-SUE PAPER WITH APPLICATION OF WET-RESISTANT AGENTS"

DESCRIPTION

TECHNICAL FIELD

The present invention relates to plants and methods for converting paper, more particularly of the so-called tissue paper, with which rolls of toilet paper, kitchen paper, handkerchiefs, paper napkins and the like are produced.

STATE OF THE TECHNIQUE

For the production of tissue paper articles, a web of cellulosic fibers is usually formed with a dry or - more frequently - wet technique. In the latter case, the web is obtained by distributing a mixture of cellulosic fibers on a formation network and then proceeding with the gradual drainage of the water until a veil of sufficient consistency is obtained, which is dried in a suitable way, by means of a Yankee roller, a TAD system or other.

The dried veil is then wound on large diameter coils. These reels are subsequently transformed, through transformation lines, into the finished product. Typically, one or more reels of cellulosic web are unwound to feed the continuous web material to processing machines which produce finished articles in the form of rolls, packs of handkerchiefs, packs of napkins or the like.

The composition of the cellulosic fiber web changes according to the final destination for the product which is made with the cellulosic fiber web.

For example, in the production of kitchen paper or similar products, a certain amount of one or more damp-resistant resins is added to the pulp of cellulose fibers with which the web is formed, i.e. resins which give the paper web a mechanical resistance at least temporary humidity. This allows the use of this type of paper to clean and dry washable surfaces, for culinary uses and the like, or even as sheets of paper to replace traditional fabric towels.

Examples of wet-resistant resins for these uses are described in the following US patents: 6,852,197; 6,702,923; 6,423,179; 6,207,013; 6,149,769; 6,059,928; 5,760,212; 5,264,082; 5,138,002; 4,981,557. The content of these documents is an integral part of this description.

Since these resins are introduced into the pulp of cellulosic fibers and water, all the web produced in the paper machine has substantially the same composition and the same wet resistance characteristics. Typically, for the production of the webs of cellulosic fibers a system is used in which the dough is fed continuously on a felt or a cloth through one or more inlet boxes. An example of a headbox for this use is disclosed in U.S. Pat. 5,560,807.

In products intended for other types of use, the wet resistance is not desired, but rather constitutes a drawback. In particular, in the production of toilet paper it is necessary that the cellulosic fiber veil is such as to be disposed of in contact with water to allow it to be easily disposed of in sanitary systems, avoiding clogging of pipes and facilitating its degradation in septic tanks and in waste water systems. purification. In this case, no damp-resistant resins are added to the cellulosic mixture with which the tissue paper web is produced, or a minimal quantity is added.

It is clear from the above that in a production line, or in a converting line, a reel is fed from time to time intended for the production of papers without wet strength (hygienic papers) or alternatively wet resistant for the production of kitchen paper or similar.

If one wishes to pass from one production to another on the same plant, it is necessary first of all to run out the paper reels present in the unwinder that feeds the line, or to replace the partially consumed reels with others of different composition. This operation is complex and involves a long downtime of the line, which negatively affects productivity and therefore the cost of the finished product, especially considering that tissue converting lines operate at web speeds that can reach and exceed 1000 m. / min.

This makes the production line inflexible or in any case increases the economic costs of production and therefore the cost of the finished product.

PURPOSES AND SUMMARY OF THE INVENTION

According to a first aspect, an object of a possible embodiment of the present invention is the realization of a production method or process which allows to obtain greater flexibility, or to produce products intended for different uses, even simultaneously on the same processing line. a cellulosic material and preferably a cellulosic material of indefinite length, i.e. typically in the form of a web or web.

By cellulosic material we mean, in general, a semi-finished material obtained from the deposition of one or more layers containing cellulosic fibers. According to a particularly advantageous embodiment, the invention relates in particular to a method for processing or converting a web or a plurality of tissue paper webs obtained by a wet process, i.e. in which the web containing cellulosic fibers is obtained starting from an aqueous suspension of cellulosic fibers and any other components, additives, fillers, or the like. The present invention, however, can also be applied to processes of production, transformation or processing of plies or layers or sheets of so-called dry paper, i.e. obtained with the "air-laid" technique, in which the cellulosic fibers are deposited to form a veil, subsequently consolidated in a suitable manner, without being brought into aqueous suspension.

According to a different aspect, an object of an embodiment of the present invention is the realization of a plant or line for converting tissue paper or other cellulosic material, which is more flexible, or which allows the simultaneous production of products destined for uses. different.

According to a further aspect, an object of an embodiment of the invention is the realization of a method or of a plant or production line which allows to produce mixed packages containing products intended for different uses, such as kitchen paper and toilet paper. .

In the following, reference will be made frequently to tissue-based products, since the present invention allows to achieve particular advantages and benefits when applied to this type of material. Moreover, it must be understood that the invention is not limited to this particular type of material, since in some cases it may also find advantageous application to other products, in which it is necessary to impart or improve the wet strength characteristics in species of based products. of cellulosic fibers or other types of materials based on non-woven fibers.

Basically, according to a possible embodiment, the invention relates to a plant for converting tissue paper, comprising a path for said tissue paper, at least one unwinder for unwinding at least one reel of tissue paper and, downstream of said unwinder, at least a converting machine, for transforming the tissue paper coming from said unwinder, and along said path at least one applicator to apply at least one damp-resistant agent to said tissue paper.

According to a possible embodiment, the moist-resistant agent is a humid-resistant resin, but the possibility of applying agents of another nature is not excluded.

According to a possible embodiment, the applicator is arranged between the unwinder and the converting machine.

In a possible configuration of the invention, the applicator is arranged and made to apply the damp-resistant agent on a longitudinal portion of the tissue paper coming from said reel, having a width smaller than the overall width of said tissue paper.

The transformation machine can be any machine, or a series of machines, for example a machine for the production of napkins or handkerchiefs, a machine for the production of interleaved articles or other. According to a particularly advantageous embodiment, however, the converting machine comprises a rewinder. Other groups, devices or machines can be combined with the converting machine, such as for example embossing, embossing and laminating groups, springing, printing, coupling groups to couple two or more plies together or other machinery useful for the production of a product. finished with particular aesthetic or functional characteristics.

In a possible embodiment, the rewinder comprises means for distributing the wet-resistant agent directly into the winding zone. Alternatively, the wet-resistant agent can be applied upstream of the rewinding zone.

The rewinder can advantageously be a central rewinder, but preferably it will be a peripheral rewinder or a combined rewinder with mutually coordinated peripheral and central winding systems.

If necessary, a drying device may be provided downstream of the applicator which applies the wet-resistant agent. This dryer can be placed upstream of said transformation machine, so that the web material reaches the already dried transformation machine.

According to a possible embodiment, the plant comprises a system for dividing the tissue paper coming from said reel into at least two longitudinal portions, and separate paths for said at least two portions, at least one respective machine being arranged along each of said separate paths. transformation to transform said two portions into different products. Alternatively, a single path will be provided and (in the case of production of products in rolls) the web material or tissue paper will be wound to form a series of rolls, all of a length substantially equal to the width of the web material coming from the parent reel (s). placed in an unwinder or other suitable device of the plant.

If several separate paths are provided, a rewinder can be arranged in each of said separate paths. Alternatively, said paths can comprise at least partly different machines.

According to a different aspect, an advantageous embodiment of the invention relates to a method for the production of articles in tissue paper, comprising the steps:

- unwinding at least one veil of tissue paper from a reel;

- applying at least one moist-resistant agent to said tissue paper web;

- transforming said web of tissue paper into said manufactured articles.

The tissue paper web is preferably transformed into rolls, although the possibility of producing other types of articles, for example folded, such as handkerchiefs or napkins is not excluded.

In a possible embodiment of the method according to the invention, the damp-resistant agent (preferably but not exclusively a damp-resistant resin) is applied on a longitudinal portion of said web of tissue paper, having a width smaller than the overall width of said web. .

According to a method of carrying out the method of the present invention, the paper web is divided longitudinally into at least two portions, said moist-resisting agent being applied to a first of said portions and said moist-resisting agent not being applied to a second portion. The different longitudinal portions are transformed into artifacts of different types. It is to be understood that by "longitudinally splitting" the web material into several longitudinal portions it is not necessarily meant a physical separation between two or more portions, by means of a cut or a longitudinal break line. Rather, this term is intended to physically or even functionally divide the web material into several longitudinal portions. In the second case, the longitudinal portions are not separated from each other during processing, but possibly after processing, in the step of cutting the rolls or dividing them into longitudinal strips sent to a bending or other type of machine.

The longitudinal portions into which the web of tissue paper is divided can possibly be separated and fed to distinct plant sections, but according to a possible embodiment of the method they will remain joined and fed to a single line or plant section, to eventually be cut after further processing operations, such as for example a winding phase. In this case the rolls or logs of wrapped paper will be cut by a cutting-off machine also in correspondence with the ideal separation line of the two or more portions in which the web material has been separated (in the sense mentioned above).

According to a possible embodiment of the method of the present invention, the portions into which the tissue paper web is divided are transformed into rolls of kitchen paper and said second portion of the tissue paper web is transformed into toilet paper.

If necessary, the tissue web is dried after the application of the wet resistant resin, although this is not normally necessary.

In general, the tissue paper can be composed of one, two or more plies which are coupled together in a known way, for example by springing, embossing, gluing or other, or by a combination of these techniques. The two or more plies can come from the same reel on which two or more plies are wound, or from different reels.

According to a further aspect, the present invention relates to a package of tissue paper products, comprising at least two products different for functional characteristics. The term functional characteristic means a characteristic that affects the method of use or the properties of the product, including aesthetic properties. By functional characteristic we can mean in general: the shape of the product (for example a product wound on a roll or a folded product); or the greater or lesser wet resistance and therefore the presence or absence or the greater or lesser quantity of humidoresistant agents; or the presence or absence of prints or the presence of different prints; the presence or absence of embossing, or the different conformation of the embossing; or the different size of the products, etc. It is also possible to envisage products which differ from each other by a combination of functional characteristics.

According to a particularly advantageous embodiment of the invention, the package comprises two types of cellulosic articles, preferably in so-called tissue paper, wound in rolls. According to a preferred embodiment, a first product is constituted by rolls of toilet paper and a second product is constituted by rolls of kitchen paper. In this case, the two products differ first of all for the different size, that is, for the different axial length of the rolls. Typically, to allow easy packaging, the toilet paper rolls will have an axial length equal to half the kitchen paper rolls. The two types of roll will differ, then, preferably for further functional characteristics such as: the presence of resins or other damp-resistant agents in the rolls of kitchen paper and the absence (or the presence in substantially smaller quantities) of these agents in the toilet paper. ; any differences in embossing; any differences in printed decorations.

Preferably, the ratio between the number of toilet paper rolls and the number of kitchen towel rolls will take into account not only the packaging requirements but also the different consumption of these articles in an average family. It has been found that typically the consumption of toilet paper rolls is higher than the consumption of kitchen paper rolls. For example, the package may contain two rolls of kitchen paper and four rolls of toilet paper, or six rolls of toilet paper. Larger packages can have a multiple number of rolls of the two product types.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood according to the description and the attached drawing, which schematically shows possible non-limiting embodiments of the invention. More specifically, in the drawing it shows: the

Fig. 1 a diagram of a plant according to the invention in a first embodiment; there

Fig. 2 a diagram of the plant according to the invention in a different embodiment; there

Fig. 3 a working diagram of a reel according to the method of the present invention; and the

Figures 4 and 5 are two examples of mixed packages obtainable with a plant and a method according to the invention.

DETAILED DESCRIPTION OF THE PRE-WOUNDED EMBODIMENTS OF THE INVENTION

In the following, reference will frequently be made to wet-resistant resins. This term must not be interpreted in a limiting sense, since the use of any agent, even with a different formulation compared to that of a traditional resin, which gives the cellulosic product the necessary temporary resistance to humidity falls within the scope of the present invention. to allow or facilitate its use in particular applications, for example as kitchen paper.

Fig. 1 schematically and briefly illustrates a possible transformation line configured according to the invention. The line is synthetically composed of the following components: a pair of unwinders 1A, 1B in which reels BA, BB of tissue paper web are arranged with which the converting line is fed; an embossing unit 3, in which the plies VA, VB fed by the reels BA, BB are embossed and joined together; a station 5 for applying the wet-resistant resins to the embossed webs; a rewinder 7 for the production of rolls or logs having an axial length equal to the width of the webs fed by the mother reels BA, BB present in the unwinders; a gluer that closes the free edge of the logs formed by the rewinder 7; a possible intermediate warehouse or buffer; a miter saw that divides the logs into individual rolls intended for final consumption. The gluer, the intermediate buffer and the cutting-off machine, as well as the downstream packaging machines, are not shown in the diagram of Fig.l. The individual machines that make up the line are per se known to those skilled in the art and do not require detailed descriptions here.

Station 5 may comprise one or more devices for applying the wet-resistant resins. These devices can be selected from known devices for applying liquid substances on tissue paper plies, for example of the type used in the sector of the production of perfumed wipes for hygiene and disinfection. A suitable device for this purpose is manufactured by Weko Biel AG (Switzerland), and known under the name of Weko Compact III.

Fig. 2 illustrates an alternative system scheme which implements the invention. In this diagram the unwinders and the rewinder are also omitted and the area of the line upstream of the rewinder is shown. This area includes: a path to a first VA veil; a path for a second veil VB; along the first path a printing unit 21A; along the second path a printing unit 21B; an embossing unit 23 which embosses the web VA and joins it by gluing to the web VB, to form a web material N which is fed to the rewinder, not shown.

According to the invention, the printing units 21A, 21B are used, instead of applying an ink, to distribute a humid-resistant resin on the two plies VA, VB. Printing units for use in certain tissue converting lines are known per se and can generally be adapted to apply a full-surface wet-resistant resin instead of an ink.

Alternatively, the printing unit or units for distributing the wet-resistant resins can be arranged downstream of the embossing unit rather than upstream of it. Two printing units can be provided for applying the wet-resistant resins on both faces of the embossed web material.

In any case, the wet-resistant resin applicator groups can be combined with groups that perform the actual printing decoration of the web-like material. Also in the solution of Fig.1 the unit or station 5 can be arranged differently, for example downstream of the embosser.

Regardless of the type of distribution system used to apply the wet-resistant resins on the tissue paper, the area of application of these resins can be limited, i.e. instead of applying the wet-resistant resin over the entire width of the web material, it can be distributed only on a longitudinal band of limited width. This is schematically illustrated in Fig. 3, where the main transformation steps of the web material are schematically represented starting from the large diameter reel up to the finished rolls. A reel is indicated with B, it being understood that two or more reels and / or single reels with several plies could be used for the production of the rolls. The reel B is unwound and the web material N is rewound forming the logs L. These are then cut to form rolls RA, RB.

In this schematic figure it can be seen that the wet-resistant resin is applied on a portion or zone in the form of a band or longitudinal strip S1 of the web material N, while in the adjacent zone or band S2 this resin is not applied. Since the web or the webs that make up the web material have been produced in a continuous machine without the addition of wet-resistant resins, the band S2 reaches the transformation area and in particular the rewinder without the addition of humid-resistant resins and this strip it is used to produce rolls or rolls of RB toilet paper, while the SI strip, on which the humid-resistant resin has been applied in the special station provided between the unwinder and the rewinder, is used to produce rolls of RA paper towel.

Also depending on the type of system used for the application of the wet-resistant resins, it is also possible to change during production, for example by means of a simple keyboard command, the width of the strips SI and S2. For this purpose it can be envisaged that the systems for applying the humidoresistant resins have a development equal to at least the total width of the web or web material N to be transformed and that limited portions of these systems are activated. For example, the applicator means can provide a plurality of rotating discs aligned according to the transverse direction (ie orthogonally to the direction of advance of the web material). Some of these rotating discs can be turned off, or the nozzles through which they project the wet-resistant resins onto the paper material can be closed.

If the application takes place via a printing unit, it is possible to use specially shaped distributing rollers, or more axially aligned distributing rollers which can be brought into or out of work respectively.

The logs L produced by the rewinder will ultimately have a paper portion treated with wet-resistant PA resins, and a PB portion not treated with such resins. The two portions are divided into rolls RA of kitchen paper and RB of toilet paper. The entire line is controlled by a control unit that synchronizes the position of the cutting knife of the miter saw and of the means for advancing the logs in the miter saw in such a way as to cut the two areas of the log into an adequate number of rolls RA and RB , where the separation line between the two groups of rolls coincides with the separation line of the two strips S1, S2 and therefore of the two areas or portions PA, PB, respectively treated and not treated with damp-resistant resins.

In the above, embodiment solutions have been envisaged in which the damp-resistant resins are applied on the web or on the web material upstream of the rewinder 7. This solution is preferable since the resins can be distributed in the thickness of the material and dry at least partially before wrapping the web material and form the logs L. If necessary, auxiliary drying systems can also be provided. However, the possibility of distributing the wet-resistant resins directly in the rewinding machine is not excluded. For this purpose, rewinding machines for example of the type illustrated in US patent no.

6,752,344, the content of which is fully incorporated in the present description.

Also in this case it is possible to modify the width of the strips S1 and S2 respectively treated and not treated with the wet-resistant resins according to the specific production requirements.

Ultimately, with the method and the plant according to the invention it is possible to produce, from the same reel or from the same plurality of reels, a single-ply or multi-ply web-like material which is partially treated and partially untreated with damp-resistant resins. The material can thus be divided into two portions with which to produce two different types of finished articles. The rolls RA and RB appear, however, to the consumer substantially identical to each other (with the possible exception of the axial length which will be greater for the RA and RB rolls of toilet paper and smaller for the RB rolls of toilet paper). Alternatively, the possibility of producing in parallel and simultaneously, starting from the same parent reel (or from a plurality of parent reels) finished products that also differ externally, for example due to a different embossing, is not excluded. To this end, embossing units with different designs can be used for the different types of finished products that come out of the same processing line. Similarly, a differentiation between the products (for example kitchen paper and toilet paper) can be obtained by using, alternatively or in combination with embossing, different printed designs for the different products.

These two types of rolls of different quality and substantially the same appearance (or differentiated, if required) can be packaged, for example, in packs that contain both products, so that the consumer can purchase multiproduct packages with particular aesthetic characteristics. .

In addition to the advantages obtained from the point of view of presentation of the finished product, the method and the plant according to the invention also make it possible to make the production line more flexible, passing from the production of toilet paper to the production of kitchen towels without replacing the reels in the car. It is also possible to modify the quantity of kitchen towel rolls and the quantity of toilet paper rolls produced simply by changing the width of the SI and S2 strips without stopping the production line. All the machines or stations that make up this line, in fact, are interfaced with one or more programmable electronic control units that allow the production parameters to be modified directly from the keyboard on the machine console.

According to a further aspect of the present invention, the application of damp-resistant agents, such as for example damp-resistant resins, in the converting phase can also take place on cellulosic web-like materials already containing damp-resistant agents added to the mixture with which it has been formed the starting material. In this case, the application of resins or other damp-resistant agents in the converting phase, for example upstream of the rewinder, it is possible to reach higher contents of damp-resistant agents than what can be obtained with the addition of these agents in the only dough in the paper mill. A higher wet strength is thus achieved. Also in this case, the damp-resistant resin or resins or other damp-resistant agent can be added over the entire width of the cellulosic web material, or only on a longitudinal portion of it, to obtain two different products at the exit of the line, starting from same coil or to the same series of coils.

Fig.4 schematically shows a mixed package, in which rolls of toilet paper RB and rolls of kitchen towel RA are contained. The rolls can be obtained from a line of the type shown in Fig. 3, with the foresight to realize in each log L areas PA and PB of such an axial length as to obtain from each log an integer number of rolls RA and RB where the rolls RB have an axial length equal to about half of the RA rolls. In this way the packaging is facilitated, as can be clearly understood from Fig. 4. In fact, in this way a regular and easy-to-handle package during the production and storage phase is obtained, with (in the example) two rolls of RA kitchen paper and eight rolls of toilet paper, the rolls of toilet paper being superimposed on top of each other. pairs placed side by side with the rolls of kitchen paper. It is to be understood that the number of rolls may vary from that illustrated. For example, it is possible to provide four rolls of toilet paper and two of kitchen paper, or three rolls of kitchen paper and six of toilet paper, as shown by way of example in the package of Fig. 5, etc.

In practice, in order to obtain an adequate number of rolls RA and RB, since the axial height or length A of the rolls RA is equal to double the axial length B of the rolls RB (B = A / 2), the method of the present invention is preferably implemented by dividing the web fed to the rewinder into two portions S1, S2, with a width defined as follows: a first portion or strip S1 of the web (intended to form the rolls RA of height A) has a width approximately corresponding to a multiple ( n) the base length (A) represented by the height of the largest rolls; the second portion S2 of the web has a width approximately corresponding to a multiple (m) of said base length (A), which can be different from the multiple (n) which defines the width of the first strip or portion S1. Typically it will be m = 2n or 3n.

By "approximately corresponding to" is meant a dimension which differs from the exact measure of an entity corresponding to a value determined by the width of the cutting edge (s), which are normally generated when the log L is divided into single rolls. In the traditional technique, each log generates a head trim and a tail trim to eliminate the two outer edges of the web material, which may have irregularities. The method of the present invention does not exclude the opportunity to eliminate an intermediate trim in the border area between the porzini PA and PB of each log L, to eliminate any areas in which there is a quantity of damp-resistant agents not determined in a manner precise, i.e. an uncertain or possibly variable quantity along the development of the web material.

It is understood that the drawing shows only an exemplification given only as a practical arrangement of the invention, since it can be found to vary in shape and arrangement without however departing from the scope of the concept that informs the invention itself.

Claims (24)

CLAIMS 1. A plant for converting tissue paper or other cellulosic material into web, comprising a path for said cellulosic product, at least one unwinder for unwinding at least one reel of cellulosic material and, downstream of said unwinder, at least one converting machine, for transforming the cellulosic material coming from said unwinder, characterized in that at least one applicator is arranged along said path to apply at least one moist-resistant agent to said tissue paper. 2. Plant as per claim 1, characterized in that said applicator is arranged between said unwinder and said converting machine. 3. Implant according to claim 1 or 2, characterized in that said applicator is arranged and made to apply said moist-resistant agent on a longitudinal portion of the cellulosic material coming from said coil, having a width smaller than the overall width of said cellulosic material. 4. Plant as per claim 1, 2 or 3, characterized in that said transformation machine is a rewinder. 5. Plant according to claim 4, characterized in that said rewinder comprises means for distributing the damp-resistant agent directly in the winding area. 6. Plant according to one or more of the preceding claims, characterized in that it comprises a drying device arranged downstream of said applicator. 7. Plant as per claim 6, characterized in that said dryer is arranged upstream of said transformation machine. 8. Plant according to one or more of the preceding claims, characterized in that it comprises: a system for dividing said cellulosic material coming from said coil into at least two longitudinal portions, and separate paths for said at least two portions, along each of said separate paths at least one respective transformation machine being arranged to transform said two portions into different products. 9. Plant according to claim 8, characterized in that different transformation machines are arranged in said two separate paths for the two paths. 10. Method for the production of tissue paper products, comprising the steps: - unwinding at least one web of a cellulosic material from a reel; - applying at least one moist-resistant agent to said at least one web; - transforming said at least one veil into said manufactured articles. 11. Method according to claim 10, in which said web is transformed into rolls. Method according to claim 10 or 11, wherein said damp-resistant agent is applied on a longitudinal portion of said web, having a width smaller than the overall width of said web. 13. Method according to one or more of claims 10 to 12, wherein said web is divided longitudinally into at least two portions, to a first of said portions said wetting agent being applied and to a second portion not being applied said wet agent -resistant; and in which said first and said second longitudinal portions are transformed into manufactured articles of different types. 14. Method according to claim 13, wherein said first and said second longitudinal portion of the web are separated and fed to distinct plant sections. 15. Method as per claim 13 or 14, wherein said first portion of the web is transformed into rolls of kitchen towel and said second portion of the tissue web is transformed into toilet paper. 16. Method according to one or more of claims 13 to 15, wherein said first portion of the web has a width approximately corresponding to a first multiple of a basic length and said second portion of the web has a width approximately corresponding to a second multiple of called base length. Method according to one or more of claims 10 to 16, wherein said web is dried after the application of the wet resistant resin. 18. Method according to one or more of claims 10 to 17, wherein said wet-resistant agent is a wet-resistant resin. 19. Method according to one or more of claims 10 to 18, in which said at least one web contains at least one damp-resistant agent and in which, during the transformation step, a further damp-resistant agent is added to at least a portion of the web. 20. Method according to one or more of claims 10 to 19, wherein said cellulosic material is tissue paper. 21. A package of cellulosic products in tissue paper comprising at least two types of products, characterized by different characteristics of resistance to humidity, achieved through a different content of moist-resistant agents. 22. Packaging according to claim 21, comprising at least one roll of kitchen paper and at least one roll of toilet paper. 23. Package as per claim 22, comprising a number of toilet paper rolls equal to double or an even multiple of the number of kitchen paper rolls. 24. Packaging according to claim 22 or 23, in which the toilet paper roll or rolls have an axial length equal to approximately half the axial length of the kitchen towel rolls.