WO2006131950A1

WO2006131950A1 - Method and machine for producing a composite article

Info

Publication number: WO2006131950A1
Application number: PCT/IT2006/000425
Authority: WO
Inventors: Riccardo Cecconi; Stefano Muroni
Original assignee: Fintex & Partners Italia S.P.A.
Priority date: 2005-06-10
Filing date: 2006-06-07
Publication date: 2006-12-14
Also published as: ITFI20050130A1

Abstract

A machine (11) for producing a composite multi-ply web material (38) having a plurality of continuous plies (32, 34, 36). The machine comprises at least a first mechanical element (22) with grooves (26) and projections (28) and a first guide member (41) comprising at least a first series of guide elements (40) positioned at the level of said grooves (26) and extending at least partially therewithin.

Description

'Method and machine for producing a composite article

DESCRIPTION Technical field

The present invention relates to a machine and a process for producing composite materials and elastic bands for hygienic products, such as diapers, training pants or the like. State of the art

Machines are known serving to produce composite materials of the elastic band type to adapt a hygienic product, such as baby diapers, to the body shape of the user.

For this purpose polymer films with elastic properties are commonly used, i.e. polymer films that can be stretched and deformed by elongation remaining in the substantially elastic range, so that when the film is released it returns approximately to its original configuration, or has a limited permanent deformation, typically within 10% of the initial length after 3 elongation cycles at 80%.

From a film of this type elastic strips are produced which are applied to the article to give it the necessary fit and to allow it to be adapted or applied to the user. In baby diapers elastic films of this type are used to produce the closing tabs of the diaper.

In "training pants" used nowadays to facilitate changing from using a diaper to using normal pants, strips of elastic film are used to form the side bands of the article, which is worn like normal pants, but has the structural and functional properties of a diaper.

In particular, in this application the article has large surfaces made of elastic polymer film.

As contact of the polymer film with the skin would be unpleasant and, especially in use in baby diapers, might give rise to phenomena of cutaneous irritation, systems have been studied to coat the polymer film with plies of more comfortable material.

The use of plies of coating material with textile fibers is known, which also give the product a better "handle", not only for the person wearing it, but also for the person who handles it. Fiber coatings are therefore used also on elastic films used for components of the diaper that do not come into contact with the skin of the user.

US patent n. 5,422,172 discloses a laminate formed of an elastic film bonded to a ply of nonwoven and a relative method of production. The polymer film is extruded directly in the nip of a calender, through which one or two card webs are fed. The fibers are bonded directly to the extruded film. This process requires complex machinery, as the film must be extruded directly at the inlet of the calender. Moreover, when the product thus obtained is pulled and elongated, this causes breakage of the fibers. According to other techniques the web of fibers is welded to a preformed film. This type of product has not proved to be satisfactory, because if the nonwoven is applied to the polymer film holding the latter in the stretched position, when the laminate obtained is released and the film returns to its non-elongated position, the nonwoven becomes wrinkled. Moreover, in these techniques the film is elongated, i.e. pre-stretched in machine direction (MD), that is, in the direction parallel to the direction of feed of the material. On the other hand, when the semi-finished product is used to produce absorbent articles or garments (such as diapers or the like), elasticity in a cross direction (CD), or prevalently cross direction, is generally required. This is because in the diaper manufacturing phase, if the elastic product is fed aligned with the diaper, the production speed is much greater than the speed it would have if the elastic band were to be fed in the cross direction and then rotated:

If the film is laminated to the web of nonwoven, without first having been stretched and elongated, the nonwoven obstructs elongation of the film during use and the fibers can detach or break. Alternatively, elastic nonwovens would have to be used, but these have a high cost.

US-A-2003/0105446 describes a composite laminated product comprising an intermediate polymer film laminated to two webs of fibers. Also in this case the film is extruded directly in the machine that performs lamination with at least one of the two plies of fibers. The composite product is then subjected to elongation in the elastic range to break the fibers and give the finished article the elasticity of the film. The possibility of perforating the film is also described. This production process is complex and unsatisfactory due to breakage of the fibers, which is however necessary to obtain a semi-finished product with adequate elastic properties at the end of the production line.

Further methods for producing an elastic film and fiber laminate are described in US-A-2003/0084986 and in US-B-6, 537,930, US-A- 2003/0022582 and in US-B-6,255,236.

EP-B-0737462 describes a composite material composed of a non- elastic polymer film on which a ply of flocked fibers is formed. This material is utilized in particular as a topsheet in feminine sanitary napkins. The film has a perforation to allow the passage of body fluids. Also known is the production of a multi-ply elastic composite comprising at least one inelastic ply forming corrugations, to provide increased softness and fit in contact with the skin of the user, and simultaneously ensure elasticity to the finished product. An article of this type is shown in Figure 1. In particular, an elastic composite 1 , see Figure 1 , can be formed of an elastic ply 3, applied to which are plies 5 and/or 7 of inelastic material, joined to produce corrugations which, when the composite 1 is pulled, allow the elastic 3 to be tensioned while the inelastic ply 5 and/or 7 yields the excess material without in turn requiring to be subjected to tension. US-A-5683787 describes a method to obtain an article of the type illustrated in Figure 1. In particular, multi-ply elastic composites produced with different materials and relative production methods are described for example in US-B- 4,935,287, US-B-4,891 ,258, US-B-4,863,779, US-B-4,741 ,944, US-B- 4,720,415, US-B-5,628,741 , US-B-4,857,067 and US-B-5,543,206, US-B- 4,720,415, US-B-4,209,563 and WO90/03464. More specifically, US-A-2,075,189 describes an elastic laminate produced by tensioning a ply of rubber and subsequently gluing thereover a further ply of flat rubber, to form corrugations once the elastic laminate is released in the unstretched position.

US-A-4,446,189 describes an elastic laminate produced with flat inelastic fibers, stitched, by means of embossing cylinders, to a ply of unstretched elastic material, subsequently subjecting the composite to traction to obtain permanent deformation of the inelastic fibers, to form corrugations once the elastic is released in the unstretched position.

US-A-5,683,787 describes a multi-ply elastic structure produced - A - similarly to the previous one, in which at least one flat inelastic ply is joined to an unstretched elastomeric ply, subsequently subjecting the composite to tension to obtain permanent deformation of the inelastic fibers. In this case the plies are joined to one another by sealing to produce a liquid-tight multi- ply structure.

The multi-ply composite obtained is generally mechanically stressed, with low mechanical properties and minimum comfort for the user. Moreover, frequently it can have imperfections, damages and be easily ruined during processing or use. In addition, the machines for producing this type of composite are also slow and difficult to control.

Further, US-A-4418123 describes a method for joining a ply of nonwoven to a flexible laminar membrane, by means of a hot-melt adhesive sensitive to pressure, under tension or when unstretched, using a suction roll and provided with projections, to form a folded multi-ply composite. This type of machine allows processing with decreased mechanical stress on the material being processed.

To date, notwithstanding developments in technology, it is still problematic and the need is felt to produce simple and inexpensive machinery to process these material in an even more delicate and progressive way, and to produce composites with improved properties of elasticity, mechanical resistance and comfort in contact with the skin of the user, in particular for use in hygienic products. Objects and summary of the invention

An object of the invention is to provide a machine for producing materials and elastic bands which is less expensive and of simpler construction, which allows easier control of the manufacturing process and overcomes or reduces at least some of the aforesaid advantages of existing machines.

A further object of the present invention is to provide a method, which facilitates and/or speeds up production of an elastic composite with improved mechanical characteristics at a reduced cost.

According to a first aspect, the invention relates to a machine for producing a composite multi-ply web material comprising at least a first mechanical element with grooves and projections, and a first guide member comprising at least a first series of guide elements arranged at the level of the grooves and extending at least partially therewithin.

In particular, the plies of the multi-ply composite typically and advantageously comprise a ply of elastic material, in particular an elastic polymer film, and at least one nonwoven or preferably two nonwovens, which have substantially inelastic behavior. The nonwoven is fed between the guide elements and the grooves of the mechanical element to gradually form therein waves or curves which extend in cross direction (CD), i.e. with ridges extending longitudinally according to the direction of feed (machine direction - MD) of the web material.

The guide elements accompany the ply of inelastic material inside the grooves to facilitate forming of the corrugations, as will be explained in greater detail hereunder.

The multi-ply composite is thus characterized by at least one outer surface of inelastic material with corrugations or scores, with greater or lesser depth, corresponding to the areas joining the various plies.

According to a preferred embodiment of the invention, the first mechanical element is a moving feed element of at least one of said plies and typically of one of the plies of inelastic material. In this way a relative movement between the web material forming said first ply and the first mechanical element is avoided, consequently avoiding the onset of friction stresses on the processed material.

Preferably, according to an advantageous embodiment of the invention, the machine has a second mechanical element cooperating with the first mechanical element, said plurality of plies being fed between said first and said second mechanical element. In this way, the plies are subjected to calendering between the two mechanical elements, preferably both comprised of cylinders rotating at approximately the same peripheral speed as the feed speed of the plies. Therefore, they can be used to join the plies together, i.e. by heat-sealing, resulting in plasticization or partial melting of the , fibers forming the ply or plies of nonwoven, the elastomeric film or both. Alternatively, glues, optionally heat activated, can be applied according to a pattern. The glues can be distributed at the level of the projections of the first mechanical element, at which the plies are joined. It would also be possible for the mechanical elements to be of another type, such as belts, moving surfaces or the like.

When a material is required to be formed with plies of nonwoven or other inelastic material on both sides of the elastomeric film or other elastic ply, it is advantageous for the second moving element also to be provided with grooves and projections. Guide elements similar to those associated with the first moving element and for the same objects can be associated with the grooves of the second moving element.

According to a particular aspect of a preferred embodiment of the invention, in the case in which both mechanical elements are grooved, these grooves are produced so that the projections of one element are set opposite the projections of the other, and respectively the grooves of the one are set opposite the grooves of the other. The opposite projections are advantageously used to join the plies in parallel contact strips. According to a particularly interesting aspect of the invention, guide elements facilitate insertion of the corrugated plies into the grooves of the mechanical elements, in order to form corrugations in the ply of inelastic material very gradually, already prior to contact with the mechanical elements, as will be described in greater detail hereunder. In this way plies of inelastic material of considerable width, such as a few meters, or other types of particularly delicate materials, can be processed in a faster and safer way; in fact, the corrugations created very gradually in the inelastic material before it enters the machine allow better control of formation thereof, and considerably decrease the possibility of wrinkling, imperfections or damages in the finished product.

In a possible embodiment, the corrugation is gradually imposed on the inelastic ply by providing for each of said guide members, in addition to a first series of guide elements extending inside the grooves of the respective mechanical element, also a respective series of auxiliary guide elements, interposed and staggered with respect to the first series of guide elements.

Advantageously, according to a possible embodiment, the auxiliary guide elements are positioned inclined with respect to the relative principal guide elements, to progressively move towards said guide elements until they are adjacent thereto in proximity to the respective mechanical element. With respect to the feed path of the inelastic ply to be subjected to corrugation the guide elements and the auxiliary guide elements are positioned so that said ply enters the space between the guide elements and the auxiliary guide elements and, moving forward therebetween, is forced to take a corrugated shape due to the progressive movement of said elements towards each other.

Advantageously, the auxiliary guide elements are positioned at the level of the projections of the respective mechanical element, and their end is preferably positioned in proximity to said respective mechanical element.

The guide elements and the auxiliary guide elements (where present) are advantageously composed of linear elements in the form of wires, bars, stems or the like, of suitable rigidity to impose a corrugated shape on the inelastic ply and are made of material with a low coefficient of friction, such as metal or plastic. They extend in a longitudinal direction lying in a plane parallel to the direction of feed (machine direction - MD) of the material being processed.

One advantage of the present invention is offered by the fact that the material being processed is not subjected to tensions during the processing steps.

Another advantage is offered by the fact that as the process to form the corrugations can be better controlled, damage or breakage of the material can be avoided.

Further advantages are offered by the fact that plies of inelastic material of different dimensions and strengths can be processed with substantially higher speeds. A further advantage is offered by the fact that the quality of the finished product is better. In fact, this composite has good properties of elasticity and mechanical strength, and a reduced production cost.

Yet another advantage of a preferred embodiment of the invention is offered by the fact that the process to join the welding strips between the various plies is improved, as it takes place between projections of opposite elements. Moreover, the welding pressure can be adjusted more accurately by adjusting the pressure between opposite elements.

Further advantageous characteristics and embodiments of the machine according to the invention are indicated in the appended dependent claims and will be described in greater detail hereunder with reference to some non- limiting embodiments.

According to a further aspect, the invention relates to a method for producing a composite multi-ply web material, comprising at least one elastic ply, typically an elastic elastomeric film, and at least one inelastic ply, typically a nonwoven ply, joined together, including the steps of:

- feeding a first inelastic ply along a feed path according to a direction of feed; forming in said first inelastic ply corrugations in a cross direction to the direction of feed, i.e. with ridges and grooves extending in the direction of feed;

- joining said first inelastic ply to a first face of an elastic ply.

Contrary to known methods for producing corrugations in cross direction

(CD), in the method according to the invention, the inelastic material is first taken to the corrugated arrangement, preferably without being subjected to inner tensions, and then made to adhere by gluing, welding or in another suitable way, to the elastomeric film or other elastic material.

According to a preferred embodiment of the invention, the following steps are also provided: - feeding a second inelastic ply along a feed path according to a direction of feed;

- forming in said second inelastic ply (36) corrugations crosswise to the direction of feed, i.e. with ridges and waves extending in the direction of feed; - joining said second inelastic ply to a second face of said elastic ply.

According to an advantageous embodiment of the method according to the invention, the corrugations in the first and optionally in the second inelastic ply are formed by feeding the inelastic ply between opposite mechanical members extending parallel to the direction of feed of the inelastic ply, said mechanical members being arranged and designed to force the inelastic ply to gradually take a corrugated shape in the direction transverse to the direction of feed.

According to a further embodiment of the method according to the invention, the corrugations in the first and optionally in the second inelastic ply are formed between the grooves of a grooved element and guide elements extending at least partially in said grooves.

To obtain a more regular formation of the corrugations also at high speed and/or on plies of considerable width, in an advantageous embodiment of the invention the corrugations are initially formed between a first series of guide elements and a second series of auxiliary guide elements, positioned staggered with respect to one another, the guide elements of the first series being interposed between the auxiliary guide elements of the second series moving gradually towards each other in the direction of feed of the relative ply, so that said ply is forced to take a corrugated shape between said guide elements and said auxiliary guide elements. Advantageously, the inelastic ply on which said corrugated shape has been imposed can be fed between the guide elements and grooves of a grooved element in which said guide elements extend. Brief description of the drawings

The present invention will be better understood and its numerous objects and advantages will be apparent to those skilled in the art, with reference to the accompanying schematic drawings, which show a non- limiting practical embodiment of said invention. In the drawing: Figure 1 shows a very schematic representation of the essential elements of an elastic composite exemplifying the state of the art;

Figure 2 shows a schematic side view of a machine according to one embodiment of the invention;

Figure 3 shows an enlarged detail of Figure 2; Figure 4A shows an enlarged section according to the line IV-IV in

Figure 3;

Figure 4B shows a variant of embodiment with respect to Figure 4A;

Figure 5 shows an enlarged view according to the line V-V in Figure 2;

Figure 6 shows an enlarged detail of Figure 5; Figure 7 shows a schematic representation of a side view of a machine according to another embodiment of the invention;

Figures 8A and 8B show enlarged details of Figure 7;

Figure 9 shows enlarged sections according to the lines A-A, B-B, C-C, D-D, E-E and F-F in Figure 8A; Figures 1OA and 10B show an elastic composite according to the invention respectively unstretched and under traction;

Figure 11 schematically shows the steps to form a diaper utilizing elastic bands produced according to the invention; Figure 12 shows a schematic side view of a machine according to the invention in a different embodiment; and

Figure 13 shows an enlarged local cross section of a composite elastic material unstretched (i.e. not stressed under traction) in a modified embodiment. Detailed description of some preferred embodiments of the invention

In the drawings, in which the same numbers correspond to the same parts in all the various Figures, with initial reference to Figures 2 to 6, a machine 11 to produce an elastic composite 38 with a plurality of plies or webs 34, 35 and 36, see Figure 2, comprises a first mechanical element 22 and a second mechanical element 24.

In particular, according to the embodiment shown in Figure 2, the mechanical elements 22 and 24 are produced as rotating cylinders between which the plies 34, 35 and 36 are fed.

The cylinders 22 and 24 have annular grooves 26, 30 and annular projections 28, 32.

The ply 35 is advantageously composed of a film of elastic material, such as an elastomeric polymer. Elastic polymer films suitable for this application are, for example:

A) Polyurethane UE30 S MATT L Supplier: Chiorino Spa

Via S.Agata 9 13900 Biella Italy

B) Elastic bubble film AB 1312/99 Supplier: RKW AG Rheinische Kunststoffwerke

Alkorstrasse 6 83512 Wasserburg/lnn (GERMANY)

C) Elastic film Flexaire 100 Supplier: Tredegar Industries Inc. 1100 Boulders Parkway Richmond Virginia 23225

D) Elastic film EXXON

Supplier: ExxonMobil Chemical Europe Bayton Technology & Engineering Complex

5200 Bayway Drive Baytown Texas 77520-2101

E) Elastic film HB001 XC001 8(110-40um) Supplier: Lo Presti Via XX Settembre,30

22100 Como

The elastic polymer film has an elasticity in cross direction (CD) and preferably also in longitudinal direction (MD). The properties of elasticity in the two directions can be different from one another. In place of elastic polymer films, elastic nettings can be used as elastic ply, for example the elastic nettings marketed with the names Rebound 750, 1000, 1500, 2000 and 2500 by Conwed Global Netting Solution, Minneapolis, MN 55414, USA.

The plies 34 and 36, which have substantially inelastic properties, are preferably composed of plies of nonwoven, formed by continuous filaments or by staple fibers, consolidated with various possible techniques, such as card webs, needle punched mechanically or by hydro-entanglement, chemically bonded, using heat treatment, by adding binders, or in another way, spunbonded, plies of air-laid paper, or any other material, preferably of a fibrous or textile nature, inelastic, i.e. substantially less stretchable with respect to the elastic film.

One or other or also all the plies forming the article can be heat- sensitive.

The machine according to the present invention also allows the use of further and different materials, in particular and advantageously softer and more delicate materials, according to the product to be produced. Associated with each of the grooved elements composed of rollers 22 and 24 are respective guide members 41 and 43, respectively comprising guide elements 40 and 42 which extend from an area upstream of the cylinders 22 and 24 to inside the grooves 26 and 30 of said cylinders.

In the particular embodiment shown in Figures 2 to 6, the guide elements 40 and 42 are preferably designed in the form of filaments, stems, bars or rods fixed to a frame 44 and 46 respectively, and form rake or comb structures, as will be described in greater detail hereunder.

The plies 34, 35 and 36 are preferably unwound from reels, not shown, and fed along feed paths. Positioned along the feed paths of the plies 34, 36 are return cylinders 52, 54, guide members 41 and 43 and the cylinders 22 and 24 respectively. A feed path of the intermediate elastic ply 35 extends between the two feed paths of the two inelastic plies 34, 36. It would also be possible for the individual plies to be fed from in-line production machines, instead of from reels. For example, the two plies 34, 36 can be formed directly in line by respective carding machines or by other machines for producing a nonwoven, while the elastic ply 35, for example an elastic polymeric film, could be formed directly by an extruder.

It must be noted that the plies 34 and 36 initially have a flat or smooth surface, i.e. without corrugations in the path between the cylinders 52 or 54 and the guide members 41 or 43, and are subsequently fed over part of the frame 44 or 46 to be inserted between the guide elements 40 or 42 of the rake or guide member 44 or 46 and the cylinder 22 or 24.

Figure 3 shows an enlarged detail of Figure 2 in the contact area between the two cylinders 22 and 24, where the three plies 34, 35 and 36 are joined.

In particular, it can be seen how the ply 34 or 36 is inserted between the elements 40 or 42 of the rakes 41 or 43 and the grooved cylinder 22 or 24.

Moreover, it can be seen how, according to the invention, the elements 40 and 42 of the rakes 41 and 43 extend inside the grooves 26 or 30 along almost the entire contact area between each cylinder and the respective ply 34 and 36, the ends 40E and 42E extending advantageously beyond the contact area and beyond the plane containing the axes of the cylinders 22, 24 (i.e. beyond the position of minimum distance between the two cylinders) to accompany the plies 34, 35 and 36 also during delivery beyond the nip between the cylinders 22, 24.

By feeding each ply 34, 36 between the guide members 41, 43 and the cylinders 22, 24, gradual and progressive corrugations are produced on the plies 34 and 36 and the final product or composite 38 is also accompanied in delivery from the machine, again gradually and progressively.

The manufacturing process of the composite 38 is thus controlled more accurately, making it possible to avoid or considerably reduce imperfections or damages that the material can sustain during processing in conventional machines.

Figure 4A shows an enlarged section according to line IV-IV in Figure 3, showing in greater detail how the ply 34 is advantageously fed between the guide elements 40 and the cylinder 22 forming waves or curves; the ply 36 is fed between the guide elements 42 and the cylinder 24 forming waves or curves and the ply 35 is fed between the cylinders 22 and 24, or between the guide elements 40 and 42 respectively in a substantially flat way.

The plies 34 and 36 are laminated to the ply 35 in the grooves of the corrugations, which have been formed therein by the projections 28 and 32 of the two cylinders 22, 24. The grooves 26 of the cylinder 22 are for this purpose advantageously positioned opposite the grooves 30 of the cylinder 24, while the projections 28 of the cylinder 22 are advantageously positioned opposite the projections 32 of the cylinder 24. In this way the plies 34, 35 and 36 are joined together by means of pressure produced between opposite projections 28 and 32.

In a particularly advantageous embodiment of the invention, at least one of the cylinders 22 and 24 is heated, in order to join the plies 34, 35 and 36 by heat welding by means of at least partial melting of the material. Furthermore, the projections 28 or 32 of at least one of the two cylinders

22 and 24 can be frontally engraved or knurled, to improve and facilitate welding of the plies 34, 35 and 36; the projections of the other cylinder can also be knurled or engraved, or alternatively smooth.

Upon delivery from the machine, the composite 38 is thereby characterized by flutes, of a greater or lesser depth, in the machine direction (MD) due to the plies 34 and 36 over-fed crosswise and welded in the grooves. In other words, the two outer plies are provided with corrugations in cross direction (CD) with ridges and grooves, which extend longitudinally, i.e. in machine direction (MD). Figure 4B shows an alternative embodiment to the one in Figure 4A, in which the cylinder 24 is replaced by an element 21 with a smooth surface 25; the element 21 can for example be a sliding surface, a belt or the like, or also a cylinder devoid of grooves. In this case, the composite material 38, which is obtained, will be provided with a single scored or corrugated outer ply.

In this embodiment, the ply 34 runs advantageously between the cylinder 22 and the guide elements 40, while the ply 35 runs between the cylinder 22 and the element 21 , or between the guide elements 40 and the smooth surface 25 or yet again between the inelastic ply 34 and the smooth surface 25.

In this case the projections 28 of the cylinder 22 press on the smooth surface 25 to join the plies 34 and 35 in substantially, the same way as described previously.

Figure 7 schematically represents a machine according to an embodiment of the invention similar to the one in Figure 2, but which differs therefrom substantially in that it comprises more complex guide members indicated as a whole with 51 and 53 and each comprising two structures or systems with opposite rakes or combs, the purpose of which is to guide and form corrugations on the plies 34 and 36, respectively, even more gradually before they are fed to the cylinders 22 and 24, respectively.

In particular, the system of opposite rakes forming the guide member 51 is used to guide the ply 34 being fed to the cylinder 22, while the system of opposite rakes forming the guide member 53 is used to guide the ply 36 being fed to the cylinder 24. Figures 8A and 8B show an enlarged detail of the "system with opposite rakes" 51 which can advantageously and preferably be produced with guide elements 40 of a first rake or comb, similar to the rake or comb formed by the guide elements 40 of the guide member 41 (see Figures 2 to 6) and auxiliary guide elements 4OS of an upper rake. These guide elements 40 and the auxiliary guide elements 4OS are positioned inclined and converging along the feed path of the respective plies 34 and 36. This means that they tend to join towards the cylinder 22 and are positioned according to the same pitch but staggered with respect to each other, in the sense that the guide elements 40 are intercalated between the auxiliary guide elements 4OS, as will be described in greater detail hereunder.

The system of opposite rakes forming the guide member 53 can be designed with the guide elements 42 similar to those of the guide member 46 (see Figures 2 and 3) and auxiliary guide elements 42S, in substantially the same way as described previously for the guide member 51.

In Figure 8B it can be seen how the auxiliary guide elements 4OS, extending until adjacent to the elements 40, are interrupted in proximity to the respective projections 28 of the cylinder 22, with surfaces 4OC preferably mating with the outer cylindrical surface of the projections 28. In this way, the ply 34 formed with corrugations is gradually fed and accompanied by the auxiliary guide elements 4OS to the grooves 26.

The elements 40 instead extend inside the respective grooves 26, in substantially the same way as the embodiment described previously with reference to Figures 2 and 3. Figure 9 shows enlarged and successive sections according to the lines

A-A to F-F in Figure 8A, in which it can be seen how corrugations are very gradually formed in the ply 34 by means of the guide elements 40 and of the auxiliary guide elements 40S of the system of opposite rakes forming the guide member 51. In particular, in the section A-A it can be seen how the elements 40 are positioned spaced apart adjacent to one another, while the auxiliary guide elements 4OS are spaced apart adjacent to one another in alternate configuration with respect to the elements 40. In this section the ply 34 is inserted between the auxiliary guide elements 40S and the guide elements 40S without touching them.

The section B-B shows the guide elements 40 and the auxiliary guide elements 40S moved towards one another in contact with the ply 34, which is tangent to all the circumferences defining the cross sections of the rods or bars forming the guide elements 40 and 40S. In the section C-C the guide elements 40 and the auxiliary guide elements 4OS start to compress the ply 34 forming first slight corrugations therein.

In the section D-D the guide elements 40 and the auxiliary guide elements 4OS are substantially adjacent and deep corrugations are formed in the ply 34, which extend crosswise to the direction of feed, i.e. to machine direction.

This last configuration continues until the auxiliary guide elements 4OS end, see the section E-E, to make way for the annular projections 28 of the cylinder 22, preferably and advantageously with a mating surface 40C to accompany the ply 34 onto the projections 28 as gradually as possible.

In the section F-F, the plies 34, 35 and 36 are joined at the level of the nip between the cylinders 22, 24.

The configuration of the guide member 53 is substantially the same as that of the guide member 51 and is therefore not described in greater detail.

Figures 10A and 10B schematize the finished product or composite 38 in a relaxed and taut condition, respectively.

Figure 11 schematically shows the steps to produce a diaper.

In particular, according to the schematic illustration in Figure 11 , a diaper can be produced starting from a flat extension of material 62A- not forming the subject matter of the present invention - suitably formed, on which plies of suitable material are deposited, and can subsequently be folded over itself and joined on flaps 64A and 64B to form the actual diaper 62B.

Therefore, feed reels 57, 59 and 61 are essentially provided in an unwinding direction parallel to the direction of feed-see arrow P-of the diaper 62B.

The reel 57 is used to deposit a ply of absorbent material 59 - not forming the subject matter of the present invention - centrally on the flat extension of material 62A. The feed reels 61 and 63 are instead used to deposit the composite 38 in order to form the flaps 64A and 64B. These flaps 64A and 64B are used both to close the material 62A and to form the diaper 62B, and to produce the space required for the legs of the user.

It should be noted that the composite 38 must be deposited on the material 62A in order to obtain elasticity in cross direction (CD), i.e. with the scores in cross direction with respect to machine direction.

Figure 12 shows a schematic side view of a different embodiment of the machine. In this embodiment two cylinders indicated with 22 and 24 are once again provided, equipped with annular grooves 26 and 30 respectively, and annular projections 28 and 32. The numerals 34 and 36 indicate substantially inelastic plies forming the outer portions of the composite web material 38, between which the intermediate elastic ply 35 is interposed. Joining of the plies 34, 35 and 36 can advantageously take place through welding performed with pressure between the annular projections 28, 32 of the two rollers 22 and 24.

As can be observed in Figure 12 the path of the plies 34 and 36 extends in this case according to a substantially different shape with respect to the one illustrated in the previous embodiments. In fact, the paths of the web materials or plies 34, 36 extend for an angle of approximately 270° around the respective cylinders 22, 24, guide rollers 100 and 102 being provided for the plies 34 and 36 respectively.

Positioned about the cylinder 22 is a series of rollers 111, 13, 115 and 117 forming as a whole a guide member of the substantially inelastic ply 34. The number of rollers positioned around the cylinder 22 can vary and differ from the number represented; for example, a single roller 117, or a higher number of rollers, such as two, three or even more than four rollers can be provided. The path of the ply 34 can consequently differ with respect to the one represented in Figure 12. The rollers 111 , 113, 115 and 117 are grooved and the annular projections positioned between the grooves of said rollers are positioned at the level of the grooves 26 of the cylinder 22. The diameter and/or position and/or depth of the grooves of the rollers 111 , 113, 115 and 117 varies along the feed path of the material 34 in the sense that starting from the roller 111 to end at the roller 117 there is a gradually increasing penetration of the projections of the rollers 111-117 in the grooves 26 of the cylinder 22. The ply 34 guided by the rollers 111 - 117 around the cylinder 22 is thus gradually pushed inside the annular grooves 26 of the cylinder 22 forming waves along the cross direction of the ply 34, i.e. waves with ridges adjacent to one another along approximately a cross direction with respect to the direction of feed of said ply 34. In substance, in this way ridges and grooves like the ones indicated in Figure 1 or in Figure 4A, 4B are obtained, once again due to gradual penetration of the ply 34 in the grooves of the mechanical guide element composed of the rotating cylinder 22. A similar arrangement of rollers indicated with 121 , 123, 125 and 127 is provided around the grooved cylinder 24. Also in this case, there is a gradually increasing penetration of the projections of the rollers 121 -127 in the grooves 30 between the projections 32 of the cylinder 24, in the sense that annular projections 121 penetrate the grooves 30 of the roller 24 to a lesser extent than the projections of the roller 123 and these penetrate to a lesser extent than the projections of the roller 125, which in turn penetrates to a lesser extent than the projections of the roller 127.

Therefore, also for the ply or web material 36, waves with a succession of ridges and grooves are gradually produced approximately in cross direction along the feed path of the ply 36 around the cylinder 24.

With this configuration, a multi-ply composite 38 is thereby obtained, substantially with the same form and the same behavior as the one illustrated in Figure 10. Also in the configuration in Figure 12, one or other of the two cylinders

22, 24 can be omitted or remain idle to operate with only one inelastic ply 34 or 36.

A description is provided hereinbefore of systems, machines and methods configured in order to obtain a composite material 38 on which the substantially inelastic plies 34 and/or 36 have a substantially uniform sequence of corrugations approximately in cross direction, i.e. waves with a constant pitch. However, this condition is not strictly necessary. In fact, it is possible, and in some cases desirable, to produce a composite web 38 in which areas devoid of corrugations are interposed between areas provided with ridges and grooves, i.e. corrugations, of the inelastic ply or plies 34 and/or 36.

Figure 13 schematically shows a cross section of a portion of composite material 38 obtained with this non-uniform arrangement of the waves or corrugations of the inelastic plies 34 and 36. In the areas in which corrugations are not provided, the inelastic plies 34 and 36 rest on the intermediate elastic ply 35 without forming corrugations. For this purpose the inelastic ply 34 and/or 36 can be welded to the intermediate elastic ply 35 in spots, over the entire surface or in localized areas. The absence of corrugations in some areas of the composite material 38 means that this has characteristics of stretchability in cross direction concentrated in some longitudinal bands or strips while it does not stretch (due to the inelastic nature of the plies 34 and/or 36) in other longitudinal bands or strips intercalated with the previous ones and more specifically in those areas in which corrugations are not provided in the substantially inelastic ply or plies.

This configuration of the product is obtained simply with a suitable form of the guide members. For example, in the case of guide members in the form of combs or rakes composed of one or two series of rod-shaped elements 40, 42 or 40, 4OS; 42, 42S, some of these rod-like elements can simply be omitted at the level of the areas in which the inelastic plies 34 and/or 36 are not required to be corrugated. In the configuration in Figure 12, the same effect is obtained by omitting the annular projections in the cylinders 111-117 and/or 121-127 forming the guide members positioned around the cylinder 22 and around the cylinder 24 respectively. It is understood that the drawing only shows a possible non-limiting embodiment of the invention, which can vary in forms and arrangements without however departing from the scope of the concept on which the invention is based. Any reference numerals in the appended claims are provided purely to facilitate reading in the light of the preceding description of the accompanying drawings and do not limit the scope of protection in any way.

Claims

1. A machine (11) for producing a composite multi-ply web material (38) having a plurality of continuous plies (32, 34, 36), comprising at least a first mechanical element (22) with grooves (26) and projections (28), and a first guide member (41) comprising at least a first series of guide elements (40) positioned at the level of said grooves (26) and extending at least partially therewithin.

2. Machine as claimed in claim 1, wherein said first mechanical element (22) is a moving element to feed at least one of said plies (32, 34, 36).

3. Machine as claimed in claim 1 or 2, comprising a second mechanical element (24) cooperating with said first mechanical element (22), said plurality of plies (32, 34, 36) being fed between said first and said second mechanical element (22, 24).

4. Machine as claimed in one or more of the previous claims, wherein said guide elements (40) and said grooves (26) of the first mechanical element (22) are arranged and designed to form corrugations in a ply (34) fed between the guide elements (40) and the mechanical element (22).

5. Machine as claimed in claim 1 , comprising:

- a feed path for at least one elastic ply (32) and a feed path for at least one inelastic ply (34), said at least one mechanical element (22) being associated with the path of the first inelastic ply (34);

- at least a second mechanical element (24), cooperating with said first mechanical element (22), the path of the first inelastic ply (34) and the path of the elastic ply (32) passing between said mechanical elements (22, 24); and wherein said first series of guide elements (40) extend along the feed path of the first inelastic ply (34) and are designed and arranged to impose corrugations on the first inelastic ply (34) in a cross direction to the direction of feed, and to oblige the first inelastic ply (32) to penetrate the grooves of the first mechanical element (22).

6. Machine as claimed in one or more of the previous claims, comprising means (28; 32; 25) to reciprocally join said plies.

7. Machine as claimed in claim 3, 4 or 5, wherein said first mechanical element and said second mechanical element (22, 24) are designed and arranged to join said plies (32, 34, 36) together, preferably by welding.

8. Machine as claimed in one or more of the previous claims, wherein said second mechanical element (24) comprises grooves (30) and projections (32).

9. Machine as claimed in claim 8, wherein said first mechanical element (22) and said second mechanical element (24) are positioned so that the projections (28) of the first mechanical element (22) are opposite the projections (32) of the second mechanical element (24) and the grooves (26) of the first mechanical element (22) are opposite the grooves (30) of the second mechanical element (24).

10. Machine as claimed in claim 8 or 9, comprising a second guide member (46) associated with said second mechanical element (24) and comprising a second series of guide elements (42), positioned at the level of the grooves (30) of the second mechanical element (24) and extending at least partially therewithin, said second guide member (41) and said second mechanical element (24) being positioned along a feed path of a second inelastic ply (36).

11. Machine as claimed in one or more of the previous claims, wherein in the area of contact with the plies (32, 34, 36) forming the composite web material said grooves (26; 30) and said projections (28; 32) of said first mechanical element (22) and optionally of said second mechanical element (24) extend in the direct of feed of said plies (32, 34, 36).

12. Machine as claimed in one or more of the previous claims, wherein said first guide member (41) comprises rod-shaped guide elements (40) which extend at least partially in grooves (26) of said first mechanical element (22).

13. Machine as claimed in claim 10, wherein said second guide member (46) comprises rod-shaped guide elements (42) which extend at least partially in grooves (30) of said second mechanical element (24).

14. Machine as claimed in one or more of the previous claims, wherein said guide elements (40; 42) extend inside the grooves (26; 30) of the respective mechanical element (22; 24) beyond the area of minimum distance between said first mechanical element (22) and said second mechanical element (24).

15. Machine as claimed in claim 14, wherein said guide elements (40; 42) are rod-shaped and have curved distal ends to follow the extension of the respective mechanical element (22; 24).

16. Machine as claimed in one or more of the previous claims, wherein said mechanical element (22) is a rotating cylinder, said grooves (26) and said projections (28) having a circumferential extension.

17. Machine as claimed in one or more of claims 3 to 16, wherein said mechanical element (24) is a rotating cylinder, said grooves (30) and said projections (32) having a circumferential extension.

18. Machine as claimed in one or more of the previous claims, wherein said first guide member (41) and optionally said second guide member (46) each comprise respective auxiliary guide elements (40S, 42S), interposed between and staggered with respect to the guide elements (40, 42) of said first and optionally of said second guide member (41; 46).

19. Machine as claimed in claim 18, wherein said guide elements and said auxiliary guide elements have a rod-shaped extension.

20. Machine as claimed in claim 19, wherein said auxiliary guide elements (4OS; 42S) are positioned inclined with respect to the relative guide elements (40; 42) of the first and optionally of the second guide member (41;

46), so as to move progressively towards the guide elements (40; 42) of the first and optionally of the second guide member (40S, 42S) until they are adjacent thereto in proximity to said first mechanical element (22) and respectively to said second mechanical element (24).

21. Machine as claimed in claim 18, 19 or 20, wherein said auxiliary guide elements (40S; 42S) are positioned at the level of the projections (28;

32) of the respective mechanical element (22; 24).

22. Machine as claimed in claim 21, wherein said auxiliary guide elements (4OS; 42S) stop in proximity to the respective mechanical element

(22; 24).

23. Machine as claimed in claim 22, wherein said auxiliary guide elements (4OS; 42S) have one end with a surface (40C) mating with the projections (28; 32) of the respective grooved element (22; 24).

24. Machine as claimed in one or more of the previous claims, wherein said guide elements (40; 42) and said auxiliary guide elements (40S; 42S) are composed of wires, stems, rods or bars extending substantially along the feed path of the respective inelastic ply (32, 34, 36).

25. Machine as claimed in one or more of the previous claims, wherein said guide elements (40, 42) are made of material with a low coefficient of friction, preferably metal or a synthetic material.

26. Machine as claimed in one or more of claims 1 to 23, wherein said guide elements comprise annular projections produced on said at least one guide member (111-117; 121-127) which is produced in the form of a rotating roller.

27. Machine as claimed in claim 26, wherein said annular projections of the rotating roller forming said guide member are positioned at the level of said grooves (26; 30) of said first mechanical element (22; 24) and penetrate at least partially therein.

28. Machine as claimed in claim 26 or 27, wherein said at least one first mechanical element comprises a grooved rotating cylinder the axis of rotation of which is substantially parallel to the axis of rotation of said guide member.

29. Machine as claimed in one or more of claims 26 to 28, wherein several guide members are associated with said mechanical element, each comprising a rotating roller with respective annular projections, positioned in sequence along a path of a first continuous ply, the annular projections of each guide member penetrating the grooves of the mechanical element to a greater extent with respect to the projections of the guide member preceding it.

30. Machine as claimed in one or more of the previous claims, including: a first mechanical element composed of a first grooved rotating cylinder; a second mechanical element composed of a second grooved rotating cylinder, the first and the second grooved cylinder being positioned with substantially parallel axes and defining therebetween a nip through which the plies forming the web material are fed; around the periphery of each of said rotating cylinders, at least one guide element including a guide roller with annular projections penetrating the annular grooves of the respective rotating cylinder.

31. Machine as claimed in claim 30, wherein a plurality of guide rollers are positioned around each of said first and second grooved rotating cylinders, the annular projections of which penetrate the annular grooves of the respective rotating cylinder forming the respective mechanical element; the plurality of rollers around each rotating cylinder defining a path for one of said plies, which winds partially around the corresponding rotating cylinder, and being positioned so that the annular projections of said rollers penetrate the annular grooves of the respective rotating cylinder to an increasing extend from the first to the last roller in the direction of feed of said ply along said path.

32. Method for producing a composite multi-ply web material, including at least one elastic ply (35) and one inelastic ply (34) joined to each other, including the steps of:

- feeding a first inelastic ply (34) along a feed path according to a direction of feed;

- forming in said first inelastic ply (34) corrugations in a cross direction to the direction of feed, the ridges of which extend in the direction of feed; - joining said first inelastic ply (34) to a first face of an elastic ply (35).

33. Method as claimed in one or more of claims 32, also comprising the steps of: feeding a second inelastic ply (36) along a feed path according to a direction of feed; - forming in said second inelastic ply (36) corrugations in a cross direction to the direction of feed, the ridges of which extend in the direction of feed;

- joining said second inelastic ply (36) to a second face of said elastic ply (35).

34. Method as claimed in claim 32 or 33, wherein corrugations are formed in said first and/or second inelastic ply (34; 36) substantially without subjecting said first and/or second inelastic ply (34; 36) to traction stresses.

35. Method as claimed in claim 32, 33 or 34, wherein said corrugations in the first and optionally in the second inelastic ply (34; 36) are formed by feeding the inelastic ply (34; 36) between opposite mechanical members (26, 28, 40; 30, 32, 42; 40S; 42S) extending parallel to the direction of feed of the inelastic ply (34; 36), said mechanical members (26, 28, 40; 30, 32, 42; 4OS; 42S) being arranged and designed to oblige the inelastic ply (34; 36) to gradually take a corrugated shape in a direction transversal to the direction of feed.

36. Method as claimed in claim 32, 33, or 34 or 35, wherein said corrugations in the first and optionally in the second inelastic ply (34; 36) are formed between the grooves (26; 30) of a grooved mechanical element (22; 24) and guide elements (40; 42; 4OS, 42S) extending at least partially in said grooves (26; 30).

37. Method as claimed in one or more of claims 32 to 36, wherein said corrugations in the first and optionally in the second inelastic ply (34; 36) are initially formed between a first series of rod-shaped guide elements (40; 42) and a second series of auxiliary rod-shaped elements (4OS; 42S), positioned staggered with respect to each other, the guide elements of the first series (40; 42) being interposed between the auxiliary guide elements of the second series (4OS, 42S), extending gradually close together in the direction of feed of the relative ply (34; 36), so that said ply (34; 36) is obliged to take a corrugated shape between said guide elements (40; 42) and said auxiliary guide elements (40S; 42S).

38. Method as claimed in claim 37, wherein the inelastic ply (34; 36) on which said corrugated shape has been imposed is guided by said rod- shaped guide elements (40; 42) in grooves (26; 30) of a grooved mechanical element, in which said rod-shaped guide elements (40; 42) extend with the free ends thereof.

39. Method as claimed in claim 36, wherein the inelastic ply (34; 36) is fed between a series of rod-shaped guide elements (40; 42) and grooves (26; 30) of a grooved mechanical element (22; 24) in which said guide elements (40; 42) extend.

40. Method as claimed in at least one of claims 35 to 39, wherein at least one of said opposite mechanical members is motorized to feed the inelastic ply in contact therewith.

41. Method as claimed in one or more of claims 32 to 40, wherein said first inelastic ply (34), optionally said second inelastic ply (36) and said W

- 26 -

elastic ply (35) are joined by welding.

42. Method as claimed in one or more of claims 32 to 41, wherein said plies (34, 35, 36) are joined together by a first grooved mechanical element (22) and a second mechanical element (24) defining therebetween a

5 nip through which said plies (34, 35, 36) are fed.

43. Method as claimed in one or more of claims 32 to 42, wherein said inelastic ply or plies (34; 36) are webs of nonwoven and said elastic ply (35) is a ply of polymeric film with elasticity at least in the direction transversal to the direction of feed/

10 44. A multi-ply web material comprising: at least one elastic ply with a first surface and a second surface; at least one substantially inelastic ply, applied to said first surface and which, when the elastic ply is unstretched in cross direction, forms gathers or corrugations in cross direction with ridges and grooves extending in longitudinal direction, adhering to said elastic ply at 5 the level of the grooves of said corrugations; and wherein said inelastic ply has been taken to the corrugated position and subsequently made to adhere to the unstretched elastic ply.

45. Article as claimed in claim 44, comprising a second inelastic ply, applied to said second surface and which, when the elastic ply is unstretched 0 in cross direction, forms gathers or corrugations in cross direction with ridges and grooves extending in longitudinal direction, adhering to said elastic ply at the level of the grooves of said corrugations; and wherein said inelastic ply has been taken to the corrugated position and subsequently made to adhere to the unstretched elastic ply. 5

46. Article as claimed in claim 44 or 45, wherein said elastic ply is a polymeric film.

47. Article as claimed in one or more of claims 44 to 46, wherein said first and optionally said second inelastic ply is a non-woven web.

48. Article as claimed in one or more of claims 44 to 47, wherein 0 said plies are joined together by welding.

49. Article as claimed in one or more of claims 44 to 48, wherein said first and optionally said second inelastic ply are substantially devoid of tension and not deformed when the elastic ply is unstretched.

50. Article as claimed in one or more of claims 44 to 49, wherein said first and optionally said second inelastic ply have areas with gathers or corrugations, and areas devoid of corrugations, in which said inelastic ply rests on said elastic ply.