MXPA06005552A - A method of strenghten a fibrous body for absorbent articles - Google Patents

Abstract

The present invention relates to a method of strengthen a boundary region between a first portion (5) and a second portion (2) of a fibrous body (6) for absorbent articles. According to the invention said boundary region is provided with a pattern of compressed spots (18), the amount of compression being gradually increased in a direction leading away from an edge of said first portion (5) of said fibrous body (6). The invention also relates to an apparatus for performing said method and an absorbent body having a strengthened boundry region.

Description

A method of strengthening a fibrous body for absorbent articles TECHNICAL FIELD The present invention relates to a method and apparatus for strengthening a boundary region between a first portion and a second portion of a fibrous body for absorbent articles, such as disposable diapers, panty diapers, sanitary napkins, incontinence guards and the like. . The invention also relates to a fibrous body strengthened by said method.

BACKGROUND OF THE INVENTION Absorbent bodies for absorbent articles, such as disposable diapers, panty diapers, sanitary napkins, incontinence guards and the like, are commonly manufactured by delivering fibrous bodies on a moving bath and then compressing the bodies by passing them through tightening surfaces between a pair of rollers. By adjusting the tightening between the rollers, a desired density of the fibrous bodies can be obtained, in order to give the bodies sufficient mechanical strength and an appropriate capillary action. If the fibrous bodies have portions with different basic weights, such as a thicker portion in the central crotch portion of the absorbent article, the compression of the thin portion can be made by a pair of rollers having a cutout to accommodate the thick portion of the body, so that the compression of the portion is made by a separate pair of rollers or by the internal wall of a cut appropriately sized. If the thick portion is not fully accommodated in the cutout, its pairs placed outside the cutout have to pass through a portion of the tightening surface, between the rollers, which is digested to compress the thin portion of the fibrous body. If this occurs, there is a great risk that the desired density in the thin portion of the body will not be obtained. Also, the parts of the thick portion placed outside the cut will be compressed to an undoubtedly high density, the fibers in the body must be broken and the capillarity will be lost in those parts. The coarse portion can also be so thick that it can not be compressed to such an extent that it can for the tightening surface between the rollers, leading to a stop in the manufacturing process. For these reasons, the area of the cut becomes somewhat larger than the area of the thick portion of the fibrous body. The difference between the areas of the cutout and the thick portion of the fibrous body is, of course, dependent on the accuracy of registration of the thick portion of the bodies placed on the moving web and the trimming or cut-outs on the rotating rollers. However, even if the accuracy is high, such a difference in the areas must be present in order to ensure the thick portion of each fibrous body is accommodated within the cutout or a cut in the pair of compression rolls. The difference in areas of the thick portion of the fibrous body and the trimming in the roller have the consequence that in the thin portion a boundary region around the edge of the thick portion remains uncompressed after the passage of the tightening surface between the rollers. This boundary region has very little mechanical resistance and will break easily. It is an object of the present invention to provide means for strengthening such a boundary region.

COMPENDIUM OF THE INVENTION This objective is achieved by a method of strengthening the boundary region between a first portion and a second portion of a fibrous body for absorbent articles, characterized by the provision of said border region with a pattern of compressed zones, the amount of the compression being increased gradually in a direction that leads away from the edge of said first portion of the fibrous body. In a preferred embodiment, the area compressed by said pattern is gradually increased in a direction leading to the distance of the edge of said first portion of said fibrous body and said pattern reaches a first portion of said fibrous body. In a first alternative of the preferred modality, said pattern has a gradually increasing number of compressed areas per unit thereof, in a direction leading away from the edge of the first portion of said fibrous body, the compressed areas being compressed at the same depth in relation to the side upper portion of said first portion of said fibrous body. In a second alternative, said patterns have the same number of compressed zones per unit area, the compressed zones have a size that increases gradually in a direction that goes away from the edge of the first portion of the fibrous body, the compressed zones being compressed at the same depth in relation to the upper side of said first portion of said fibrous body. In a second embodiment, the zones of said pattern are compressed at different depths in relation to an upper side of said first portion of said fibrous body. The invention also relates to an apparatus for strengthening a boundary region between a first portion and a second portion of a fibrous body for absorbent articles, comprising a pair of rollers and means for passing a fibrous body, having at least a first portion and at least a second portion, through a tightening surface between the rollers in said pair of rollers, characterized in that at least one pattern of projections is provided on an outer peripheral surface of at least one of the rollers, whereby said pattern extends around the edges of an opening in this at least one roller, each projection projects outwardly from an outer peripheral surface of said roller and has a cross section in a plane tangential to a peripheral outer surface of said roller, and that the sum of cross-sectional areas of the projections per unit area increases gradually in a direction that leads away from the edges of said opening. In a preferred embodiment, at least one of the rollers in said pair of rollers comprises a cut-out to accommodate a first portion of a fibrous body, said opening in the pattern of projections being coaxial to the cutout, but has a smaller size, so that the pattern of projections reaches beyond the edges of said cut in its portion. In a first alternative, said projections have the same size in cross section and said patterns have a gradually increasing number of projections per unit area in directions leading away from the edges of said opening, the tightening surfaces of all the projections are they place the outer peripheral surface of said roller in the same tangential plane. In a second alternative, said pattern has the same number of projections per unit area, in directions that go away from the edges of said opening, the size of the cross sections of said projections gradually increase in size in directions that go away from the edges of said opening, the tips of all the projections being in the same plane tangential to the peripheral outer surface of said roller. In a second embodiment of such a rare device performing the method of the invention, the tips of the projections are placed in different planes tangential to a peripheral external surface of said roller. The invention further relates to a fibrous body for absorbent articles having at least a first portion and a second portion, adjacent said first portion, characterized in that a region bordering this at least one first portion and the second adjacent portion therein is provided with a pattern of compressed zones, the amount of compression in the boundary region is increased gradually in a direction away from the edge of said first portion of this fibrous body. In a preferred embodiment, the compressed area in the boundary region is gradually increased in a direction that moves away from the edge of said first portion of the fibrous body and said pattern of compressed zones arrives within the first portion of said fibrous body.

In a first alternative, said pattern has a number, increasing gradually, of compressed zones per unit area, in a direction that goes away from the edge of the first portion of said fibrous body, the compressed zone is compressed to the same depth in relation to the upper side of said first portion of said fibrous body. In a second alternative, said pattern has the same number of compressed zones per unit area, these compressed zones have a size that increases gradually in a direction that goes away from the edge of said first portion of said fibrous body, the compressed zones are compressed at the same depth in relation to an upper side of said first portion of the fibrous body. In a second embodiment, the zones in said pattern are compressed at different depths in relation to the upper side of said first portion of the fibrous body.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the appended figures, in which: Figure 1 schematically shows a side view of an apparatus for compressing an absorbent body, according to a preferred embodiment of the invention; Figure 2 shows a plan view of the apparatus of Figure 1; Figure 3 schematically shows a side view of an absorbent body after compressing the thick and thin portions; Figure 3A shows a part of the absorbent body of Figure 1 on a larger scale; Figure 4 schematically shows a plan view of an absorbent body produced by the apparatus in Figures 1 and 2; Figure 5 shows a sectional view, along the line V-V in Figure 3; Figure 5A shows a part of the absorbent body in Figure 5, on a larger scale, and Figures 6 to 11 show schematic plan views of a part of an absorption body, according to other embodiments of the invention.

DESCRIPTION OF THE MODALITIES The apparatus shown in Figures 1 and 2 comprises a first transfer wheel 1 for placing a first layer 2 of cellulose fluff-, lying in the air, on a running band 3, which may be a band of Coating sheet on top of an endless conveyor. The first layer 2 is preferably formed in a mating wheel (not shown) and then deposited on the transfer wheel 1. If the first layer 1 can be formed in synchronism with the advance of the running belt 2, the transfer wheel can be omitted and the wheel 1 can be in the form of a mat. As can be seen from figure 2, layer 2 has an hourglass configuration. The direction of the band 3 is to the right in figures 1 and 2, as indicated by the arrows. Running under the wheel 1, a second transfer wheel 4 is arranged to place a second layer 4 of cellulose fluff, lying in the air, on a central part of the first layer 2. As is evident from Figures 1 and 2, the first layer 2 extends beyond the periphery of the second layer 5 on all its sides. Thus, a fibrous body 6 having a thin portion and a thick central portion is obtained, the thin portion being the portions of the first layer extending outside the periphery of the second layer 5. A first pair of rollers 7, 8 for compression to densify the thin portion of the fibrous body 6 is disposed downstream of the wheel 4. The roller 7 of the first pair of compression rollers is provided with cutouts 9, 19, to accommodate the thick portion of the bodies 6 is say the layer 5 and the central part of the layer 2 that overlaps the layer 5, when these portions pass the tightening surface between the rollers 7, 8. The cutouts 9, 10 are thus arranged on the roller 7 so that the thick portions of the subsequent fibrous bodies, passing the tightening surface, are alternately accommodated in the cutouts 9 and 10. In order to ensure that no part of the layers 5 of the bodies 6 that pass are located outside the cut-outs 9, 10, these cut-outs have an area greater than the layers 5. In the embodiment shown, the depths of the cut-outs are equal to the height of the layers 5 or greater. The difference in areas between the cuts and layers 5, ie the tolerance required for the cuts, is among other factors dependent on the accuracy of the deposits of layers 2, 5 on the running band 3, the synchronization between the speed of the band 3 and the rotation speed of the rollers 7, 8 and also how firmly the bodies 6 are retained in the band (usually with the aid of suction).

A second pair of compression rollers, 11, 12, current is disposed below the first pair of rollers 7, 8. When the fibrous bodies 6 pass between the tightening surfaces of the rollers 11, 12, the thick portions of the bodies 6 are compressed. In Figures 3 and 3A, a fibrous body 6 is shown schematically directly after having passed the pair of rollers 11, 2. Since the cutouts 9, 10 have an area larger than the thick portion (layer 5) of the body fibrous 6, the thin portion 2 will be uncompressed in a boundary region 2a around the periphery of the layer 5. Likewise, this uncompressed boundary region 2a will have different width in the different sides of layer 5, and will also vary for the different fibrous bodies 5 successively passing the two pairs of compression rollers 7, 8 and 11, 12, respectively. The difference will often be the greatest for the edges of layer 5, being perpendicular to the direction of travel of band 3. The consequence of the uncompressed boundary region 2a is that body 6 will have very little resistance in this junction and will It will easily break during the handling of these bodies, during the steps of the remaining production and packaging or when handled by a user.

According to the invention, a pair of rollers 13, 114 to provide said border region with a pattern of compression zones is disposed downstream of the rollers 11, 12 to compress the thick portion of the fibrous body 6. Also in this case , the roller 13 which is in contact with the side of the fibrous body containing the layer 5, is provided with two cut-outs 16, 17 to accommodate the thick portions of the bodies 6, which successively pass the tightening surface between said rollers. The roller 13 is also provided with a pattern of projections 17. This pattern 17 extends around the edges of each cut 16, 17, and has a width corresponding to the width of the border region of the fibrous body 6. Likewise, the pattern it also preferably extends within the cutouts 16, 17 in its edge region. In the embodiment shown, the pattern 17 is formed by projections having a circular cross section and a semi-spherical tip. The tips of all the projections are placed in the same plane tangential to the peripheral outer surface of the roller 13, ie the projections extend to the same radial distance from the outer surface of the roller 13. This means that the projections within the cutouts they have a greater length than the projections to the outside of the cuts. Also, said pattern 17 has a gradually increased number of projections per unit area in directions leading away from the edges of the cutouts. In Figures 4, 5 and 5A, a fibrous body 6 is shown after the tightening surface has passed between the rollers 13, 14. The pattern 17 of the projections produces a pattern of compressed areas 18 in the boundary region around the body. the edges of the thick portion 5, a pattern also reaches a short distance in the thick portion, as schematically indicated in these figures. The number of zones compressed per unit area is gradually increased in directions leading away from the edges of the thick portion, that is, from an edge of the thick portion 5 towards the nearest edge of the thick portion 2. The exact position of the pattern of compressed zones in the fibrous body 18 is, of course, dependent on the registration of the thick portion of the body advanced fibrous 6 in relation to the cut 16 or 17. This record, as mentioned above, varies for the individual bodies passing the rollers 13, 14, the greater variation being in the direction of travel of the band 3. Thus, for a 6 body, the side of the thick portion that is placed forward in the direction of travel, will be closer to the adjacent wall of the cut 16 or 17 of the roller 13, than the corresponding side of the thick portion of the thick portion of the next body 6 for the rollers 13, 14. In order to ensure that the pattern of projections 17 reaches all points of the boundary region 18 around the periphery of the thick portion 5, the pattern of projections 17 will reach preferably a short distance in the respective cutout 15, 16 around its periphery. In Figures 4 and 5, the right end, as seen in the figures, of the thick portion 5, is placed closer to the adjacent wall of the cutout 15 or 16 than the left end of the thick portion, when for the rolls 13, 14. Therefore, the pattern of the compressed zones 18 reaches a greater distance in the thick portion 5 at the right end of the body 6 than at its left end. This means that also the pattern of compressed zones 18 and has a smaller extension to the outside of the right end of the thick portion, than to the outside of its left end. The distance, which with the pattern of projections reaches in the respective cutout, is preferably selected so that at least one row of projections in the pattern 17 arrives in the thick portion 5 of the fibrous body 6 around its periphery each time the registration of the coarse portion with a cutout 15, 16 on the roller 13 is within the determined tolerance. The width of the pattern 17 along each edge should be chosen to ensure that the pattern covers the total width of the uncompressed region 2a of the thin portion 2 of each body 7 passing the rolls 113, 14. As indicated above , the width of the uncompressed region 2a along each side of the thick portion 5 will also vary due to the variation in the register with the respective cut 10, 10 in the roller 7 of the fibrous bodies 6, which pass successively rollers 7, 8. The thick portion 5 of the fibrous body 6, shown in Figures 4, 5 and 5A, have been compressed to the desired density by the rollers 11, 12. Therefore, the number of compressed zones per unit area in the coarse portion 5 it must be smaller than that of the total area per unit area compressed by the projections in the pattern of projections 17, is smaller in order not to significantly influence the total density of the coarse portion around its edges. On the other hand, in the border region of the thin portion 2 outside the edges of the coarse portion 5, the resitance in this region is proportional to the total compressed area, the greater the area compressed per unit area, the greater the resistance of the border region. By the use of a pattern of compressed zones 18, in which the number of zones per unit area increases gradually in the direction from one edge of the thick portion 5, towards an adjacent edge of the thin portion 2, a compromise between the demands conflicting, mentioned above, is obtained. As is evident from Figure 5A, the distances a, b, c, between the zones compressed in the pattern 18 gradually decrease in a longitudinal direction leading away from the right edge of the thick portion 5. Also in lateral directions, a Similar decrease in distances is present, that is, the distance between zones along a lateral line through zone 18? is greater than the distance between zones along a sideline through zone 182, the distance between zones along a sideline through zone 182 is greater than the distance between zones at along a lateral line through the I83 zone, etc. It has also been observed that when the zones compressed in the pattern 18 are waxed together, the density of the fibrous material in the areas around the zones will also increase. This phenomenon is believed to be caused by the interaction between the fibers and, therefore, is dependent on the type of fibers in the body 6, the length of the fibers and also the distance between the fibers, ie the effect is more pronounced More fibrous material is compressed. In the described embodiment, the strengthening of the boundary region between the coarse portion 5 and the thin portion 2 is done in a separate step after the steps of compressing the coarse and thin portions to a desired density. Of course it is possible to perform this strengthening simultaneously as the compression of the thin portion, by the supply of the rollers 7, in Figures 1 and 2, with patterns of projections corresponding to the patterns 17 on the roller 13. In such case, the compression of the coarse portion is preferably performed before compression of the legal portion. It is also possible to provide the roller 11 in Figures 1 and 2 with patterns of projections similar to the patterns 17 on the roller 13 and perform strengthening of the border region simultaneously as the compression of the thick portion of the desired density. A third possibility is to make the compression of the thick and thin portions of the fibrous body and the strengthening of the border region in a single step. This can be done by sizing the cut-outs 9, 10 in the roller 7, so that the depth of the cuttings is less than the heights of the thick portions in such an extent that the density desired in the thick portions is obtained and at the same time provide the roller 7 with patterns of projections corresponding to the patterns 17 in the roller 13. Of course it is also possible to perform the compression of the thick and thin portions in the same step by a suitable sizing of the cut-outs 9, 10 in the roller 7 and performing the strengthening of the boundary region in a step separated by the rollers 13, 14. It is possible to perform the strengthening of the boundary region before compressing the thick and thin portions. Such an order has the advantages of easy penetration of the loosely attached portions and easier alignment of the opening in the pattern of projections and the thick portion, since no cooking effect of this portion due to compression has occurred. If the strengthening of the border region is carried out as a last stage, ie after the compression of the thick and thin portions, the increase of the density of the fibrous material in areas around the zones, due to the interaction between fibers will be more increased and the length of the projection does not need to be so large, since the thick and thin bodies will have a decreased thickness after compression.

It is also possible to provide the roller 14 with projection patterns similar to the patterns on the roller 13 with a central opening in the patterns, which correspond to the positions of the cutouts in the roller 13. It is also pointed out that if the fibrous body is strengthened performed in a separate step, the cutouts 16, 17 on the roller 13 can be made independent if these steps are performed before, after or intermediate the compression steps of the thick and thin portions. In the described embodiment, the gradual increase in the compressed area per unit area in the fibrous body 6 is obtained by a pattern 17 having a gradual increase in the number of projections per unit area in directions that move away from the edges of the body. the cut-outs 15, 16. However, it is possible to vary the size of the projections in the pattern instead of the number of projections per unit area. Thus, the gradual increase in the compressed area per unit area will be obtained by a gradual increase in the size of the projections in the pattern. A third way of varying the amount of compression in the boundary area of the thin portion is to vary the depth of the compressed zones in the fibrous body 6 by having a gradual increase in the length of the projections in the pattern 17 in directions away from the edge of cutouts 15, 16. For such a pattern, the depth of the compressed area in the border region will vary. Of course it is possible to combine two or all of the three ways, mentioned above, to vary the number of compressions in the pattern of compressed zones, that is, the variation in the number of compressed zones, the variation in the size of the compressed zones and the variation of the depth of the compressed zones. The tips of the projections can have other shapes in addition to hemispheres, for example a tapered or conical configuration, a hexagonal configuration, a rectangular configuration, etc., but the projections will preferably be tapered to the outside, so that they can penetrate the body fibrous, while evading a considerable part of the fibrous material on its sides. The cross section of the projections is understood as the cross section of the greater part of the projection that penetrates the fibrous body, during the strengthening of the border region of the fibrous body. The pattern of compressed zones does not need to be a pattern of spaced zones, but it is gradually desired that the pattern be obtained by interconnected bar gratings or a combination of gratings and points. The schematic plan views of different patterns to be used in the present invention are shown in Figures 6-11. In all these figures, which show a part of a fibrous body, according to the invention, the thick portion of the body has a reference number 5 and the thin portion has the reference number 2, and the tolerance ET for the alignment of the thick portion and a cut is shown in broken lines. In Figure 6, a pattern similar to pattern 17 in Figure 4 is shown in greater detail. The compressions, shown as black dots, all have the same thickness and the number of zones increases gradually in directions that go away from the edge of the coarse portion. In Figure 7, the pattern 18 of composed of compressed lines connects with each other. These compressed lines all have the same thickness and the number of lines increases gradually in directions away from the edge of the thick portion. Such a pattern of compressed lines is made by a roller having a grid pattern, which projects from its peripheral surface.

In Figure 5 the pattern 20 of the compressions is a combination of the pattern shown in Figures 6 and 7, ie a combination of the compressed lines and dots. In Figure 9, the pattern 21 is a pattern of compressed lines, which are parallel to each other and at the same distance from each other. Nevertheless, the thickness of the compressed lines is gradually increased in directions that go away from the edge of the thick portion. In Figure 10, the pattern 22 is also a pattern of compressed lines that are parallel to each other. The compressed lines all have the same thickness and the number of lines increases gradually in directions that go away from the edge of the thick portion. In Figure 11, the pattern 23 is a pattern of compressed points, arranged at the same distance from each other. the distance being measured between their centers. However, the size of the compressed points is gradually increased in directions that go away from the edge of the thick portion. In this aspect, the "first portion" and the "second portion" of the absorbent body, defined in the claims, refers to regions having different properties, such as different thickness, density or composition, for example, when a small core is placed on top of a large core, a First, thick region is built in the center and is surrounded by a second thin region. It is noted that the terms "thick portion" and "thin portion" refer to the state in the final body. There may be cases in which the thin portion in the sense of the present invention, which is placed around the central portion, is thicker than said central portion, but is then compressed to be thinner in the compressed state than the central portion. Such a case and similar cases are included in the present invention. There may also be other reasons than differences in thickness to avoid compression of certain portions of a fibrous body, while compressing a portion thereof, for example a central portion may have a desired density or other properties, which are risky if the central portion It is subjected to the pressure of rollers that compress the portions outside the central portion. Such situations are also taken into account by the present invention. Likewise, it could be the outer part that is protected so that, instead of a cut, a part that projects to the outside of the roller performs the compression of the central part, the bordering region becomes stronger after it arrives from the edges of the edge. the central part towards its center.

The apparatus, shown schematically in Figures 1 and 2, is preferably a part of the continuous manufacturing line for disposable absorbent articles, such as disposable diapers, panty diapers, sanitary napkins, incontinence guards and the like. If the band 3 running is a band of coating material, a second band of coating material is superimposed on this band and the row of compressed fibrous bodies contained therein, after the possible process steps involved, such as the provision of elastics. If the band 3 is not a band of facing material, the bodies 6 are transferred to a running strip of facing material. Since the volume of the body 6 is not reduced to any significant extent by the strengthening of its boundary region, it is possible to perform the strengthening step after the bodies are enclosed between two bands of facing material. The described embodiment can, of course, be modified in various ways, within the scope of the invention, instead being composed of two layers 2, 5 lying in the air, delivered separately in the band 3 running from the fibrous body 6 be lying in the air in the same mold. The layer or layers in the fibrous body may contain other components mixed with the cellulose fluff, such as particles of super absorbent material. Also other materials used for the compressible cores can be used, such as other natural fibers, synthetic fibers or their mixtures, peat, etc. Layers 2, 5 may have other configurations, layer 2 may be, for example, rectangular and layer 5 may have an hourglass configuration. Also, the described patterns of the projections and compressed zones need not be separate patterns, and may, for example, be part of a pattern to provide the total fibrous body with compressed or similar zones, the part of such pattern being placed outside the border region it can then consist of a regular or irregular pattern. The method and apparatus according to the invention can, of course, be used for the strengthening of other fibrous bodies, laid to the air, such as carded cores, wet laid or other types of compressible cores. The scope of the invention, therefore, will be limited only by the content of the following claims.

Claims (17)

1. A method for strengthening a boundary region between a first portion and a second portion of a fibrous body for absorbent articles, characterized in that said boundary region is provided with a pattern of compressed zones, the amount of compression being increased gradually in a direction that goes in moving away from an edge of said first portion of the fibrous body.

2. The method according to claim 1, characterized in that the compressed area is gradually increased in a direction that goes away from the edge of said first portion of the fibrous body.

3. The method, according to claim 3, characterized in that said pattern reaches the first portion of the fibrous body.

4. The method, according to claims 1, 2 or 3, characterized in that said pattern has a gradually increasing number of compressed zones per unit area, in a direction that moves away from the edge of the first portion of said fibrous body, the zones compressed being compressed at the same depth in relation to an upper side of said first portion of the fibrous body.

5. The method, according to claims 1, 2 or 3, characterized in that the pattern has the same number of zones compressed per unit area, these compressed zones have a size that increases gradually in a direction that goes away from the edge of the portion thick of said fibrous body, the compressed zones being compressed at the same depth in relation to an upper side of said first portion of the fibrous body.

6. The method, according to claims 1, 2 or 3, characterized in that the zones in said pattern are compressed at different depths in relation to an upper side of said first portion of the fibrous body.

7. Apparatus for strengthening a boundary region between a first portion and a second portion of a fibrous body for absorbent articles, comprising a pair of rollers, and means for a fibrous body, having at least a first portion and at least a second portion, through a tightening surface between the rollers in said pair of rollers, characterized in that at least one pattern of projections is provided on an outer peripheral surface of at least one of the rollers, whereby said pattern has an opening around its edges in which the projections extend, each projection projects outward from an outer peripheral surface of said roller and has a cross section in a plane tangential to the peripheral edge surface of said roller, and that the sum of the transverse areas of the projections per unit area is gradually increased in a direction that goes away from the edges of said opening.

8. The apparatus, according to claim 7, characterized in that at least one of the rollers comprises a cutout to accommodate a first portion of a fibrous body, said opening in the pattern of projections being coaxial to the cutout, but has a smaller size so that the pattern of projections reach beyond the edges I said cut in its portion.

9. The apparatus, according to claims 7 or 8, characterized in that said projections have the same size in cross section and said pattern has a number that gradually increases the number of projections per unit area in directions that go away from the edges of said opening, the tips of all the projections are in the same plane tangential to the peripheral outer surface of said roller.

10. The apparatus, according to claims 7 or 8, characterized in that said pattern has the same number of projections per unit area, in directions that go away from the edges of said opening, the size of the cross sections of said projections increasing gradually in directions that go away from the edges of said opening, the tips of all the projections being in the same plane tangential to the peripheral external surface of said roller.

11. An apparatus for strengthening a boundary region, between a first portion and a thin portion of a fibrous body, for absorbent articles, comprising a roller pair and means for passing a fibrous body having at least a first portion and at least a second portion portion, through a tightening surface, between the rollers of said pair of rollers, characterized in that at least one pattern of projections is provided on an outer peripheral surface of at least one of the rollers, whereby said pattern has an opening around its edges where the projections extend, each projection projects to the outside from an outer peripheral surface of said roller, and the tips of the projections are in tangential planes different from an outer peripheral surface of said roller.

12. A fibrous body for absorbent articles, having at least a first portion and a second portion, adjacent to at least a first portion, characterized by a border region between at least a first portion and the second portion there adjacent, is provided with a pattern of compressed zones, the amount of compression in the border region being gradually increased in a direction away from the edge of said first portion of the fibrous body.

13. The fibrous body according to claim 12, characterized in that the compressed area of the border region is gradually increased in a direction away from the edge of said first portion of the fibrous body.

14. The fibrous body, according to claims 12 or 13, characterized in that said pattern of compressed zones arrives within the first portion of said fibrous body.

15. The fibrous body, according to claims 12, 23 or 14, characterized in that said pattern has a gradually increasing number of compressed areas per unit area, in a direction that goes away from the edge of the first portion of said fibrous body, these compressed zones are compressed to the same depth in relation to the upper side of said first portion of the fibrous body.

16. The fibrous body, according to claims 12, 13 or 14, characterized in that said pattern has the same number of zones compressed per unit area, these compressed area has a size that increases gradually in a direction that goes away from the edge of the same. the first portion of said fibrous body, said compressed zones are compressed at the same depth in relation to an upper side of said first portion of the fibrous body.

17. The fibrous body, according to claims 12, 13 or 14, characterized in that said zones in this pattern are compressed at different depths in relation to an upper side of said first portion of this fibrous body.