MX2007011970A - Absorbent article containing a density gradient in at least two directions, and method for the manufacture thereof. - Google Patents

Abstract

An absorbent article includes a liquid permeable cover, a baffle material, and an absorbent structure disposed between the cover and baffle material. The absorbent structure includes a retention zone having a varying density gradient in at least two dimensions and a protection zone having a portion with a density less than a minimum density of the density gradient in the retention zone. The retention zone may be defined in a first region of the absorbent structure having a first basis weight and the protection zone may be defined in a second region of the absorbent structure having a second basis weight that is greater than the first basis weight.

Description

ABSORBENT ARTICLE CONTAINING A GRADIENT OF DENSITY IN AT LEAST TWO ADDRESSES, AND METHOD FOR THE MANUFACTURE OF THE SAME Related Requests The present application claims priority of the Brazilian patent application number P10501157, filed on March 31, 2005.

Field of the Invention The present invention relates to an absorbent article that contains a density gradient in at least two dimensions that forms an absorption / retention layer comprising a retention zone and a protection zone and also absorbent side barriers. It also relates to a method of manufacturing said absorbent article. The present invention also relates to an absorbent article having a retention zone and one or more protection zones defined in the material of the absorbent structure having different base weights and volume.

Background of the Invention In the prior art it is known that absorbent articles such as intimate absorbents (for example, absorbent articles for female care) have as main characteristics being comfortable and discreet, with high absorption of body fluids and high dependence against leaks. Such requirements include variables that are not always combined in an effective way.

An intimate absorbent should provide comfort when used in view of being placed in the female pubic region that applies tension during movement; a larger item can cause irritation and consequently discomfort even during a short period of use. On the other hand smaller articles increase the risk of filtration as the smaller size means a smaller area of absorption. Optimal size must be accompanied by material characteristics that compensate for a more appropriate size, smaller for the product.

In addition, the shape of the absorbent is important. The anatomical fit also provides comfort in use. The absorbent articles of the prior art have an approximately rectangular format in which the vertices are rounded and have a slight narrowing in the middle part. A greater narrowing provides a better anatomical fit, however the known solutions do not combine the feature without loss of efficiency in the retention of body fluid; as a consequence, more anatomical products have a shorter life, consequently requiring replacement at shorter intervals.

The absorption characteristic of an absorbent article is determined by the absorbent material used and by the number of absorption layers provided. The known absorbent articles combine a greater number of absorption layers in order to confer greater efficiency in the product. Hygroscopic articles are also used to more quickly transport the body fluid inside the layers of the articles and in this way provide increased comfort. What commonly occurs is that better absorption is associated with a larger volume of the absorbent as a function of the greater number of layers and a greater amount of the hygroscopic article; in this way, the consuming public may need to choose between what is more discreet and what is more efficient.

Another aspect that relates to art is dependence. A dependent absorbent article is capable of retaining body fluid (in particular menstrual fluid) without any filtration which, strictly speaking, comprises a comfort feature combined with efficiency. When the limitations of the previously mentioned characteristics are not observed, for example, the thickness, the anatomical format, the absorption capacity, etc., the risks of filtration are continuous and quite frequent.

Prior art commonly solves the problem by sacrificing other characteristics, invariably eliminating the comfort, efficiency and dependence of the product; however, it is still necessary to provide a product capable of combining the functional characteristics previously described.

In relation to this aspect innumerable documents are known that propose solutions such as: Irish patent document 56006 which relates to an absorbent article, particularly a disposable diaper having a decreased density of the absorption layer starting from the bottom; the density differentiated in levels of the absorption layer allows the distribution of the fluid, in this case urine; U.S. Patent No. 3,871,378 which relates to an absorbent article comprising a low density hydrophobic cover in contiguous association with a material having an absorbent core of high hydrophobic density to promote the transmission of body fluids more rapidly from said cover to said core. Said arrangement provides a favorable density gradient to drain the fluid in the direction of the core where it is then retained; U.S. Patent No. 4,781,710 refers to an absorbent element having a density pattern comprising high low density regions separated by surrounding channels; the channels comprise a transport and stored where a storage region or a transport region separates and surrounds another storage region or transport region; the transport regions have a higher density than those of the storage regions, the density which, in turn, is greater than the density of the high regions; Brazilian patent document BR 8105365 A refers to an absorbent structure comprising a pad having a substantially rectangular shape and a density gradient such that the density of the pad increases from the center to the transverse ends; Brazilian patent document BR 0004245 A refers to an absorbent core for use in disposable absorbent articles such as baby and adult diapers, disposable training underpants or female intimate absorbers, wherein the material is distributed in such a way that they are formed within the absorbent core in at least three zones: a distribution-storage zone, an area against drainage and one or more transition zones.

In all the art referred to above, the density gradient is unidirectional, generally vertical or longitudinal / transversal. In this case, protection against filtration is partial, preventing part of the body fluid from being drained in other directions and accumulating in small fractions until extravasated.

The absorbent articles of the prior art having a unidirectional density gradient do not introduce retaining elements against the lateral extravasation, besides they do not have fluid distribution in multiple directions. If the distribution of the removed body fluid in the absorbent article is not achieved, providing less wetting of the surface of the article in contact with the body, may be necessary to place containment elements on the edges capable of supporting the fluid retained in the absorbent .

Another aspect also not achieved by the absorbent articles of the prior art is the retention of the fluid transported to the absorption core. A decreased density that starts from the core allows the drainage of body fluid in the direction of the absorption zone, but also allows the fluid to return in the direction of the outermost layers that contributes to the surface accumulation and lateral extravasation. .

The lack of a configuration comprising a body fluid distribution system not only in the direction of the absorption zone but everywhere compromises the efficiency of the absorbent article and causes a sensation of discomfort and wetness and does not perform in a manner efficient, for example, leading to the replacement of the absorbent article at shorter intervals.

Objectives of the Invention An object of the present invention comprises the provision of an absorbent article having density gradients being vertical and transverse and optionally longitudinal allowing the distribution of flow through a larger area of the article increasing the feeling of comfort in use for a longer period .

Another objective of the present invention comprises the provision of a layer of super absorbent material that covers an area of lower density to increase protection against leaks.

Another objective of the present invention comprises placing a zone of lower density underlying a hydrophobic cover zone to reduce the return of the fluid and the sensation of humidity in use.

Still another object of the present invention is to provide a method of manufacturing the absorbent article of the present invention.

Still another object of the present invention is to provide an absorbent article having improved fluid intake, storage, and prevention of filtration provided by an absorbent structure having regions of different base weights in combination with a varied density of the retention zone. Regions of different base weights can be defined by step changes or gradual changes in the basis weight of the material of the absorbent structure.

Another object of the present invention is to provide an absorbent article having an absorbent structure disposed between a cover and a spacer material, the absorbent structure including a retention zone having a density gradient variant in a dimension X defined in a first region. of the absorbent structure having a first basis weight, and a protection zone having a density of less than the minimum density in the retention zone and defined in a second zone of the absorbent article having a second basis weight that is greater than first basis weight.

Additional objects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through the practice of the invention.

Description of the Figures Figure 1 illustrates an enlarged view of the possible configurations of the absorbent article showing all the layers of the absorbent material; Figures 2A-2B illustrate a representation of the options for the absorption / retention layer of the absorbent, showing the retention zone and the protection zone and the density areas (density gradient) that vary radially outward from the maximum density to the minimum density; Figures 3 and 4 illustrate an enlarged view of the absorbent article showing the absorbent side barriers and the area of the treated permeable cover (hydrophobic area).

Figure 5A illustrates a view of the top plane of the absorbent article in a configuration without the acquisition layer and without the super absorbent barriers, which have a density gradient in the X and Y directions.

Figure 5B illustrates a view of the top plane of the absorbent article in a configuration with the acquisition layer and without the super absorbent barriers, which have a gradient density in the X, Y, and Z directions.

Figure 5C illustrates a view of the upper plane of the absorbent article in another configuration with the acquisition layer and without the super absorbent barriers, which have a density gradient in the X, Y, and Z directions.

Figure 5D illustrates a view of the top plane of the absorbent article in another configuration with the acquisition layer and the super absorbent barriers, which have a density gradient in the X, Y, and Z directions.

Figure 5E illustrates a view of the top plane of the absorbent article in yet another configuration with the acquisition layer and the super absorbent barriers, which have a density gradient in the X, Y, and Z directions.

Figure 6A illustrates a view of the upper plane of the etching pattern of the absorption layer having the preferable diamond pattern.

Figure 6B illustrates a view of the upper plane of the etching pattern of the absorption layer having the triangle pattern.

Figure 6C illustrates a view of the upper plane of the etching pattern of the absorption layer having the pattern of pictures.

Figure 6D illustrates a view of the upper plane of the etching pattern of the absorption layer having the line pattern.

Figure 6E illustrates a view of the upper plane of the etching pattern of the absorption layer having the pattern of perpendicular lines.

Figure 6F illustrates a view of the upper plane of the etching pattern of the absorption layer having the diagonal line pattern.

Figure 6G illustrates a view of the upper plane of the etch pattern of the absorption layer having a sinusoidal pattern.

Figure 6H illustrates a view of the upper plane of the etching pattern of the absorption layer having a circle pattern.

Figure 7 illustrates an embodiment of the engraving roll to achieve density variation in an engraving pattern.

Figure 8 illustrates an embodiment of another engraving roll to achieve density variation in an engraving pattern.

Figure 9A illustrates a schematic view showing the shape of the product in use and the distribution of flow within the product, with a central cross section showing the function of the absorbent material as a barrier.

Figure 9B illustrates a schematic view showing the shape of the product in use and the distribution of the flow within the product, a perspective view showing how the fluid is distributed as a function of the barriers in use and the density gradient zone .

Figure 10A is a diagrammatic cross-sectional view of an alternative embodiment of an absorbent article in accordance with various aspects of the present invention.

Figure 10B is a view of the upper plane of the incorporation of the absorbent article illustrated in Figure 10A.

Figure 10C is a top plan view of an alternative embodiment of an absorbent article in accordance with the invention, particularly illustrating an alternative configuration of the retention area.

Figure 11 is a top perspective view of an incorporation of the absorbent article according to the invention incorporating a particular configuration of the retention zone.

Figure 12 is a top perspective view of yet another embodiment of an absorbent article according to the invention illustrating a different configuration of the retention area.

Figure 13 is a perspective view of the end of an alternative embodiment of an absorbent article according to the invention, and particularly illustrates the differential heights between various zones of the absorbent structure.

Figure 14 is a bottom perspective view of a layer of the absorbent core that can be used in various embodiments of the absorbent article according to the invention, and particularly illustrates a pattern of the densified regions defined on the bottom surface of the core material absorbent.

Figure 15 is a top plan view of an alternative embodiment of an absorbent article according to the invention incorporating the configuration of the absorbent core illustrated in Figure 14.

Figures 16A to 16D are views of the upper plane of alternative recording patterns that can be defined in one or more layers of the absorbent structure of an article according to the invention.

Detailed Description of Preferred Additions Reference is now made to several embodiments of the invention, examples of which are illustrated in the figures. The incorporations are presented by way of explanation of the invention, and are not meant as a limitation of the invention. It should be appreciated that the features illustrated or described with respect to an embodiment may be used with different embodiments to produce yet another embodiment. It is intended that the present invention include such modifications and variations to the embodiments described herein.

In a particular embodiment, an absorbent article is provided comprising a partially permeable cover (1); an absorption / retention layer (3) having a density gradient in the Y direction and in the X direction, such a density gradient being in the range from about 0.06 grams per cubic centimeter to 0.20 grams per cubic centimeter, or any other density value with absorption area; a waterproof cover (5); a removable strip (7) and multiple adhesive layers (8).

The invention also comprises a method of manufacturing an absorbent article comprising the steps of: Provision of a cover sheet, an absorption / retention layer, and a bottom sheet, each having lateral and longitudinal edges; Laminating the absorption / retention layer to the cover sheet and the lower sheet in such a way that the absorption / retention layer is placed between the cover sheet and the lower sheet; Y Obtaining a density in a mechanical way, in the laminated cover sheet, and in the absorption / retention sheet in both directions X and Y, in such a way that there is a density gradient decreasing generally from the center of the cover sheet to the lateral and longitudinal edges of the article.

The invention also encompasses an absorbent article, comprising: A cover permeable to liquid; A separating material; An absorbent structure disposed between the so-called cover and the so-called spacer material, the so-called absorbent structure comprises a retention area having a variant density gradient in a dimension X defined in a first region of the so-called absorbent structure having a first basis weight , and a protection zone having a substantially uniform density less than a minimum density of the so-called density gradient in the so-called retention zone and defined in a second region of the so-called absorbent article having a second basis weight that is greater than the so-called first base weight, the so-called protection zone defined longitudinally along the opposite lateral sides of the so-called absorbent structure.

According to Figure 1, the absorbent article of the present invention comprises a partially permeable cover (1) with the contact side with the body being a low density acquisition layer (2), an absorption / retention layer (3). ) that has a density gradient in the Y direction, a lateral absorbent barrier (4), a waterproof cover (5) being the side to the garment, removable strips (7) to protect the adhesive placement, multiple layers of adhesive ( 8) responsible for keeping all the components of the product attached to each other and the layers of adhesive placement (6) responsible for keeping the product fixed to the underwear in use. In another configuration of the present invention, the absorption / retention layer (3) has a density gradient in the directions (X) and (Y).

Although incorporations of the absorbent articles according to the invention are illustrated in the figures as having a generally "dog bone" form, it should be appreciated that the invention is not limited to this form and that it encompasses any conventional form of absorbent article. , including oval, hourglass, rectangular, and others.

The absorbent article comprises a partially permeable cover (1) which can be partially treated with a surfactant and which defines a hydrophilic central zone of a length in a range from about 35 millimeters to 65 millimeters, not exceeding approximately 70% of the total area of the absorbent article. The so-called characteristic makes the body fluid permeable to the cover in the treated area where the fluids are released, and impermeable to the sides that act as a barrier to the fluids that protect the user against lateral leaks.

The acquisition layer (2) generates a density gradient in the direction (Z) that has a density that can be in the range from about 0.03 grams per cubic centimeter to 0.09 grams per cubic centimeter. The acquisition layer may include soft fibers comprising about 85% cellulose pulp fibers and about 15% polyethylene / polypropylene bicomponent fibers, or any other composition of material that serves the same purpose or use. In another configuration, the acquisition layer (2) may comprise a nonwoven fabric comprising approximately 50% polyethylene / polypropylene bicomponent fibers, or any other composition of material serving the same purpose or use.

The acquisition layer (2) has a width that can be in the range from about 30 millimeters to about 50 millimeters, and a length that can be in the range from about 50 millimeters to the total length of the finished product. The so-called low density property allows very rapid acquisition of the fluid in the article and can provide greater comfort for the user as a function of the smoothness properties thereof.

The absorption / retention layer (3) has a density in the range from 0.06 grams per cubic centimeter to 0.20 grams per cubic centimeter (or any other density value with an absorption area) and may comprise soft cellulose pulp fibers, which contains the absorbent paper and a super absorbent polymer such as sodium acrylate. The retaining / absorbing layer (3) can have an hourglass shape with a minimum width in a range from about 42 millimeters to about 75 millimeters in the center and a maximum width in a range from about 60 millimeters to about 85 millimeters in the lobes. The absorption / retention layer is divided into two zones. 1. Retention zone (3a): a region of variable density that can be delimited by a side channel recorded in a racetrack or hourglass format representing a maximum of approximately 60% of the absorption / retention layer (3) ) which has a thickness in a range from about 1.5 millimeters to about 3.5 millimeters. The so-called retention zone can have a density gradient in a range from about 0.08 grams per cubic centimeter to about 0.20 grams per cubic centimeter, preferably in a range from about 0.10 grams per cubic centimeter to 0.14 grams per cubic centimeter. The so-called retention zone has a maximum density (0.20 grams per cubic centimeter) in the center of the absorption / retention layer (3), the so-called maximum density being constant for a length of approximately 20 millimeters to approximately 200 millimeters in the direction (X) and a width of about 15 millimeters to about 40 millimeters in the direction (Y). The so-called maximum density area provides optimum fluid distribution due to the high capillarity of the same. As the distance increases from the center of the absorbent article in the direction (Y), the so-called density reduces, creating a capillary gradient and a fluid distribution gradient, obtaining minimum density of approximately 0.08 grams per cubic centimeter within the limits of the retention zone that can be delimited by a recorded channel. The so-called properties of the retention zone provide optimized distribution of the fluid in the direction (X) in the center of the absorption zone and reduce the fluid distribution on the sides of the absorbent article reducing the probability of lateral filtration and increasing the utilization of the absorbent layer. Furthermore, the rate of absorption is improved for repeated situations of discharges of body fluid, since the fibers located in the area receiving the discharge of body fluid are made less saturated as a function of the maximized fluid distribution. The so-called retention zone corresponds to the area of the absorption / retention layer (3) which has sufficient absorbent material to absorb at least 4 grams of menstrual fluid in a particular embodiment.

It is noted that the so-called density gradients can be obtained in a mechanical manner, by covering the absorption / retention layer homogeneously, having the same amount of absorbent material distributed throughout the area of the same. The so-called density gradient can be obtained in two ways: a) tapping tabs (also referred to herein as "snaps") have different heights from the center to the edges, the greater height of the plug being in the center of the absorbent article. The so-called height decreases as the distance from the center increases. Said variation in height from one area of studs to the next area may be in the range from about 0.01 millimeters to about 1 millimeter, desirably from about 0.3 millimeters to about 0.6 millimeters. b) engraving tacos that have different areas of compression, the largest area being in the center and the smallest areas in locations furthest away from the center. The area of each compression can be in a range from about 1 square millimeter to about 16 square millimeters in the center, desirably from about 2 square millimeters to 4 square millimeters, with about 0.01 square millimeters being about 2 millimeters square in the outer part of the retention zone, preferably from about 0.8 square millimeters to 1.5 square millimeters.

Said recording studs preferably have a diamond shape, but may have other patterns, such as squares, lines, perpendicular lines, diagonal lines, sinusoidal lines or shapes (e.g., waveforms), polygons, circles, triangles and others .

In the configuration where the density gradient of the absorption / retention layer (3) is of three dimensions, said gradient also varies in the direction (Z) in such a way that when the fluid approaches the ends of the product it finds greater Difficulty in the distribution, reducing the possibilities of filtration through the extremities of the product. Such configuration is especially valid for products for night use where most of the leaks occur through the extremities of the product. 2. Protection zone (3b): a region of desirable constant density surrounding the retention zone, as a maximum representing approximately 40% of the absorption / retention layer (3). Such a protection zone is the lowest density area of the absorption / retention layer (3), which has a density in a range from about 0.04 grams per cubic centimeter to about 0.10 grams per cubic centimeter, a desired density being in a range from approximately 0.07 grams per cubic centimeter to 0.08 grams per cubic centimeter. Said zone has a thickness in a range from about 2.5 millimeters to about 8 millimeters, preferably from about 4 millimeters to about 7 millimeters. This difference between the density of the center of the retention zone and the density of the protection zone is a mim of approximately 0.02 grams per cubic centimeter. Said protection zone has the property of having the lowest capillarity of the absorption / retention layer, being located underlying a hydrophobic non-woven cover area. Such characteristics, low density and the underlying hydrophobic nonwoven fabric, maximizes the prevention against lateral filtration. Said protection zone may include a channel recorded in racetrack or hourglass format, and may contain different channel designs (in terms of shape, width, and amount), being areas of mechanically compressed material that function as a barrier to the fluid and as distributors of the fluid, reducing the probability of lateral filtrations.

Said two zones also present an improvement in comfort and convenience given that the central part of the absorption / retention layer (3) has a higher density and because it comprises the area of least deformation in use, therefore allowing better absorption, the external area of the absorbent article being softer providing greater comfort and lower return resulting from the hydrophobic area of the so-called cover.

The engraving combination of the retention area and the channels of the protection zone imparts a form of the 'M' type in use, having the following benefits: to. said channels, by virtue of their density / capillarity, improve the distribution and create lateral barriers that prevent the occurrence of filtration; b. said recordings of the retention area cause preferable deformation of the product in use (from the "A" to "M" format), which by virtue of its high density, distributes fluids very rapidly in the X direction. It also generates a deep cavity (type "M") that provides lateral barriers of absorbent material that prevent filtration, while the fluid is distributed and absorbed by the absorbent core. Simulates the properties of a acquisition layer mechanically without requiring a specific material or chemical treatment to perform these characteristics.

Said combination of the retention zone and the protection zone existing in the absorption / retention layer of the absorbent article of the present invention also introduces a gradient thickness in the product, with a lower thickness obtained in the center of the absorbent article in the area. of retention and greater thickness in the protection zone.

In order to improve the protection against filtration, the absorbent article of the present invention may have absorbent side barriers.

The absorbent side barriers can be located on at least one of the sides of the acquisition layer (2), underlying the hydrophobic area of the treated roof area and on the protective zone of the absorption / retention layer (3) . Said side barriers represent additional localized absorption in the region where most of the leaks occur during use with the sides of the absorbent article. Said barriers can be considered to be made of different types of absorbent materials, such as: a) A super-absorbent hot-melt material such as HB Fuller HM1100; such super absorbent being applied in at least one line on at least one of the sides of the absorbent article as a hot melt adhesive, and said super absorbent line having a width in a range from about 0.5 millimeters to about 10 millimeters, preferably from about 3 millimeters to about 7 millimeters, and a length in a range from about 30 millimeters to about 300 millimeters, preferably from about 40 millimeters to about 60 millimeters, the concentration thereof being in a range from about 0.05 grams per side to about 5 grams per side, preferably from 0.1 grams per side to 0.3 grams per side. Such superabsorbent also has high capillarity properties assisting in the distribution of the fluid in the longitudinal direction of the absorbent article, assisting in the reduction of saturation of the main absorption area that receives the discharged bodily fluids when in use. Said property increases the absorption rate when repeated discharges of fluids occur since the absorbent fibers are less saturated, and the absorption capacity increases since the absorbent article will use a larger area of the absorbent layer. Another benefit of said material is that the placement of the super absorbent where it is desired is assured, maximizing the performance of the absorbent article. b) The material of the type placed by air containing the super absorbent in the composition thereof: said material being applied in at least one strip on at least one of the sides of the absorbent article; said super-absorbent strip has a width in a range from about 3 millimeters to about 10 millimeters, and a length in a range from about 30 millimeters to about 300 millimeters, preferably from about 40 millimeters to approximately 60 millimeters and having a basis weight in a range from 100 grams per square meter to 500 grams per square meter. A benefit of this material is that it is ensured that the super absorbent is placed in the desired place maximizing the performance of the product. Another feature is that said material may have a color that differs from the material of the absorption layer. Said difference in color assists the user in identifying the time to replace the article since the indication is provided as when the fluid reaches the protection zone. In view of the absorbent side barriers being located underlying the hydrophobic area of the treated roof area, a further benefit is that the fluid is retained in said region reducing the return of the fluid and the sensation of humidity since the hydrophobic material reduces the contact of the fluid with the skin.

The present invention differs from the prior art by having a density gradient in at least two of the three dimensions, for example in the direction (Y) and in the direction (X). Said density gradient can be obtained mechanically in the absorbent layer from the initial homogeneous density where, before compression, the density is the same in the X and Y directions throughout the absorption / retention layer. In addition, in another configuration, it contains an acquisition layer in which the density varies in the Z direction generating a total density gradient. In general the point 0,0,0 represents the maximum density of the product and this density decreases along the axes, X, Y, and Z (Figures 2A and 2B) reaching their minimum values in the protection zone (X directions) , Y) and in the acquisition layer (Z direction). The benefits of said density gradients may include any or a combination of: a) optimized absorption rate by virtue of the low density of the acquisition layer; b) Optimized absorption speed by virtue of faster fluid distribution in the X direction; c) optimized fluid distribution in the X direction by virtue of high capillarity thereof; d) optimized absorption speed in multiple discharge incidents since the fluid distribution reduces the saturation of the region receiving the fluid discharges; e) increased absorption capacity by virtue of improved fluid distribution, allowing maximized use of the absorbent core; f) optimized protection against lateral filtration since the density gradient in the X and Y directions interfere with the distribution of fluid in lateral and end parts of the product; g) reduced moisture sensation as the fluid is absorbed and distributed by means of the absorbent retention layer being located on the product side; h) Optimized shape by virtue of higher bending strength in the center of the absorbent retention layer, reducing accumulations and kinks.

It also generates a VM 'form in use, differing from the form, A' in use found in products currently on the market.

The benefits of such density and form? M 'gradients in use may include any or a combination of: a) optimized distribution of fluid in the X direction by virtue of the high capillarity thereof; b) optimized absorption rate in multiple discharges since the distribution of the fluid reduces the saturation of the region receiving the fluid discharges; c) increased absorption capacity by virtue of improved fluid distribution that allows maximized use of the absorbent core; d) increased absorption and protection capacity against lateral filtration, with the same amount of absorbent material, by virtue of the format of the product in use forming absorbent side barriers that retain fluid discharges allowing the occurrence of the acquisition; e) optimized protection against lateral filtration, since the density gradient in the Y direction hinders the distribution of the fluid in lateral parts of the product; f) optimized fluid acquisition, being a combination of different channels / mechanical engravings, without requiring additional materials; g) Optimized shape, by virtue of the higher strength in the center of the absorbent / retention layer, reducing agglomeration and twisting.

Another feature is the use of a treated deck area with a hydrophobic area upon placing the protection zone in the X direction. Said treated deck zone may add any or a combination of the following benefits to the performance of the product: a) increased absorption capacity and minimized lateral filtration, because the sides of the absorption / retention layer are hydrophobic. Said feature imposes fluid displacement in the X direction and maximizes the use of the absorbent core; b) reduction in the sensation of moisture in the user's leg area, because the hydrophobic nonwoven prevents the fluid from returning through the cover onto the sides of the pad.

Another distinction is with respect to the super absorbent side barriers, located in the hydrophobic area of the treated roof area and superimposed on the absorbent layer. Said placement can ensure that: a) the super absorbent is applied to the place where the action of the same is more necessary; b) the super absorbent is located in the optimum area in order to reduce lateral filtration and decrease humidity, because the fluid retention is located under the hydrophobic area of the cover, reducing the sensation of humidity.

The present invention can also provide a method for manufacturing said absorbent article, such method comprising the steps of: Provision of a cover sheet, an absorption / retention layer, and a bottom sheet, each having lateral and longitudinal edges; Laminating the absorption / retention layer to the cover sheet and the bottom sheet, such that the absorption / retention layer is placed between the cover sheet and the bottom sheet; and The density obtained in a mechanical manner, in the laminated cover sheet and in the absorption / retention layer in both X and Y directions, such that there is a density gradient generally decreased from the center of the cover sheet to the lateral and longitudinal edges of the article.

The method of manufacturing the absorbent article, in accordance with that previously described, may further comprise the steps of: Provision of an acquisition layer; Laminating the acquisition layer between the cover sheet and the lower sheet before the density stage obtained in a mechanical manner, such that in the acquisition layer a density is also obtained in a mechanical manner; wherein the layers in which a density is obtained in a mechanical manner provides a density gradient that generally decreases from the center of the cover sheet to the lateral and longitudinal edges of the article.

It is noteworthy that, the density stages can be obtained in a mechanical manner by, for example, engraving the cue.

Said method can still further comprise the steps of applying the absorbent side barriers on the sides.

Additional incorporations of the absorbent articles incorporating various aspects of the present invention are illustrated in Figures 10A through 15, and will be described in detail below. It should be appreciated, however, that the description noted above with respect to the absorbent articles, or various components thereof, illustrated in Figures 1 to 9 may equally belong to the embodiments of Figures 10A to Figure 15. It should be appreciated that any feature of any of the embodiments illustrated or described herein may be incorporated with any other embodiment within the scope and spirit of the present invention.

With reference to Figures 10A to 10C in particular, an embodiment of an absorbent article 100 is illustrated. The absorbent article 100 includes a liquid permeable cover 102, a spacer material 104, and an absorbent structure 108 disposed between the cover 102 and the separator 104. Various suitable materials for use as the cover 102 and the separator 104 are described above and are well known to those skilled in the art. The present invention is not particularly limited to any type or combination of materials used as the cover 102 and the separator 104. The absorbent structure 108 may include an absorbent core material 140 alone or in combination with a layer of acquisition material 148 (also referred to as a take layer). Various suitable materials for use as the acquisition material 148 are also described above and are well known to those skilled in the art. The absorbent article 100 can include any combination of applications or layers of adhesive 106 among the various components of the article. The article 100 is not particularly limited by the application or location of such adhesive layers 106.

The absorbent structure 108 includes a retention zone 110 having a variant density gradient C in dimension X, as particularly illustrated in Figures 10B and 10C. Although not limited to such a method, the variant density gradient C can be defined mechanically by etching the absorbent core material 140 in the manner described in detail above with respect to the embodiments of Figures 1 through 9.

The retention area 110 is defined in a first region 116 of the absorbent structure having a first basis weight, as particularly illustrated in Figure 10A. This basis weight may vary depending on any combination of factors, including the size and capacity of the absorbent article 100, as well as the particular type of absorbent material used to form the absorbent core 140. In a particular embodiment, the first region 116 is formed at least in part of a cellulose fluff material and has a basis weight of about 370 grams per square meter (gsm). The basis weight in the first region 116 can vary from about 200 grams per square meter to about 50 grams per square meter. Other ranges are also within the scope and spirit of the invention. Commercially available cellulose fluff materials are manufactured by eyerhauser or by Georgia Pacific. In one embodiment, the average length of wood pulp fibers is around 3.1 millimeters (by the Kajaani method). The roughness of the pulp fibers is about 34 milligrams per 100 meters, and the average denier of the pulp fibers, calculated from roughness is about 3.06 denier per fiber or filament (dpf).

The absorbent structure 108 also includes one or more protection zones 118 laterally outward of the retention area 110 and oriented longitudinally along the absorbent structure 108. The protection zones 118 may have a relatively constant density that is less than the value minimum of the density gradient in the retention zone 110. In other words, the density of the protection zones 118 in a particular embodiment is generally lower than the lowest density in the retention zone 110. The retention zones 118 are defined in a second region 120 (Figure 10A) of the absorbent structure 108 having a second basis weight that is greater than the first basis weight. For example, with reference to Figure 10A, the second region 120 may be a part of the absorbent core material 140 having an increased thickness defined in a stepwise manner. As illustrated in Figure 10A, the absorbent core material 140 may have a U-shaped channel profile, with increased height portions of the core material 140 defining the second region 120. In a particular embodiment, the second region it may also be formed of the same cellulose fluff material as the first region 116 and have a basis weight of about 490 grams per square meter, compared to the lower base weight of the first region 116. The second basis weight may vary from about from 400 grams per square meter to about 800 grams per square meter in alternative embodiments of article 100. It should be appreciated that the first and second regions 116, 120 may be formed from the same absorbent material, or from different absorbent material. It should also be appreciated that the basis weights of the first and second regions can widely vary beyond the ranges established as a function of the size and / or absorbent capacity of the absorbent article.

Even though the first region 116 and the second region 120 of different base weights are illustrated in the figures as defined by differences in the pitch mode in the thickness (in the Z direction) of the core material 140, it should be noted that gradual changes or variations in base weights are also contemplated and within the scope and spirit of the invention.

With reference to Figures 10A and 10B, the protection zones 118 are defined as longitudinal regions on opposite lateral sides of the retention area 110. In the embodiment of Figure 10B, the retention zone 110 has longitudinal end regions 112 and side sides 114. The side sides 114 extend generally to the protection zones 118. In the embodiment of Figure 10C, the side sides 114 of the retention area 110 are spaced from the longitudinally extending protection zones 118. it should be appreciated that the longitudinal dimension of the retention zone 110 may vary widely within the scope and spirit of the invention, as described above with respect to previous incorporations.

Still with reference to Figures 10B and 10C, the absorbent structure 108 includes longitudinal ends 124 and side sides 122. The protection zones 118 may extend generally along the longitudinal sides 122, as illustrated in the figures, or may also be comprising all or a portion of the longitudinal ends 124. For example, the protection zones 118 may form a perimeter or boundary region around the entire absorbent structure.

In the illustrated embodiments, the regions of the storage zone 126 are provided in the absorbent structure 108 generally in the first region 116 having the lowest basis weight. In the embodiment of Figure 10B, the storage regions 126 are defined by the longitudinal ends 112 of the retention area 110 and the longitudinal ends 124 of the absorbent structure 108. In the embodiment of Figure 10C, the storage area 126 it generally surrounds the retention area 110 and extends between the opposite longitudinal ends 124 of the absorbent structure 108. The regions of the storage zone have a density gradient Bl and B2 which may be constant, or may vary. For example, the density gradient of the regions of the storage area 126 may decrease in either or both of the X and Y dimensions from a central point (0,0,0) of the absorbent structure 108.

The density profiles of the various regions and zones of the absorbent structure 108 as described above provide the absorbent article 100 with improved fluid intake and absorption characteristics. The central retention zone 110 with the lowest base weight and highest capillarity serves to quickly take and distribute the bodily fluids to the storage zone 126 in the X direction, and to the protection zone 118 in the Y direction. stored 126 with densities Bl, B2, and lower capillarity receive the fluid from the retention area 110. Retention areas 118 with generally greater thickness in the Z direction, and lower density and capillarity, define lateral barriers against the filtration and can effectively maintain and distribute sudden fluid spills. Protection zones 118 can act as an effective source material in this regard.

The various differences in density and material of the articles 100 also provide an improved product in use adjusted to the consumer by the probability reduction of random deformation of the product, which can result in discomfort for the user and filtration. The absorbent article according to the invention is deformed into an adjustment deformation M with lateral compression with the retention area 110 defining a bottom cavity of the profile "M". This adjustment deformation M contributes to a more uniform distribution of the fluid initially within the retention zone 110 and then more evenly throughout the storage areas 126 and the protection zones 118.

Figure 11 illustrates an embodiment of an absorbent article 100 incorporating various aspects described above with respect to Figures 10A through 10C. In this incorporation, the absorbent structure includes the retention zone 110 of highest density and capillarity. The storage area 126 surrounds the retention area 110 and extends longitudinally along the absorbent structure, and the protection zones 118 are defined along the lateral sides of the structure, as described above. An etched outside channel 130 delineates the protection zones 118 from the storage areas 126. This channel 130 may extend in a longitudinal direction along each side side of the absorbent structure 108, and may define a closed channel in curl as shown in FIG. illustrated in Figure 11, or an open loop configuration. In this particular embodiment, the longitudinal ends 124 of the absorbent structure include longitudinal and protective zones 119 delineated by the channel 130. These zones 119 can be defined in the first region of lowest base weight 116 (Figure 10A) and, therefore, they can have essentially the same density and capillarity as the storage areas 126. In an alternative embodiment, the longitudinal protection zones 119 can be formed in the second region 120 of increased base weight material (as with the protection zones 118) or even a third intermediate region having a basis weight between that of the first region 116 and the second region 120, and therefore includes material of lower density and capillarity, but increased thickness.

The retaining zone 110 may include any manner of engraving pattern 134, as described in detail above. The engraving pattern can provide the retention area 110 with a varying density gradient in the X and Y directions, and can be defined by engraving rolls having either a variant surface area pattern or a bolt depth penetration pattern. variant, as described in detail above. Alternatively, the engraving pattern can be defined by a combination of engraving roll having both a variant surface area pattern and a bolt depth penetration pattern. In the embodiment illustrated in Figure 11, the engraving pattern 134 includes a wave and floral design that provides the area 110 with a gradient in the X and Y dimensions, but not necessarily in the Z direction.

Figures 16A to 16D illustrate several alternative embodiments of suitable recording patterns that can be defined in the retention zone of an absorbent article according to the invention. These patterns can be defined mechanically by engraving roller pin or bolt patterns configured to provide the retaining zone with a desired density gradient in the X and Y directions, as described above.

The retention area 110 can be delineated by an inner engraved channel 128. The absorbent structure 108 can also include any number or pattern of transverse engraving channels 132 generally defined in the longitudinal end regions of the storage areas 126, as particularly illustrated in Figure 11. These channels 132 can serve to rapidly distribute and channel the fluid from one area to the other, particularly in the event of a sudden spill or rapid fluid intake. The transverse engraved channels 132 can serve to more rapidly distribute the fluid throughout the entire storage area 126, and can also assist in the generation of a more uniform set deformation M of article 100.

It should be appreciated that any incorporation of an article 100 in accordance with the invention can incorporate any known manner of known conventional characteristics used with absorbent articles. For example, with reference to Figure 11, article 100 may include wings 111 configured to fold around the wearer's undergarment and to secure the undergarment or one another. For this purpose, an adhesive 109 or other suitable attachment mechanism, such as a micro-hook or hook-and-loop material, may be provided on the wings 111, as is well known to those skilled in the art.

The incorporation of an absorbent article 110 illustrated in Figure 12 is similar to the embodiment of Figure 11. In this embodiment, the retention zone 110 includes an engraved pattern 134 in the form of engraved depressions having an inverted or truncated pyramid shape. separated by areas of elevated areas. This particular pattern 134 defines channels of varying depth in the X and Y directions provides the retention zone with the desired varying density gradients, as described above. The grille or pattern of relatively small depressions recorded can also serve to quickly distribute the fluid on the surface of the retaining area 110, particularly in the case of a sudden spill of fluid.

The view of article 100 in Figure 13 illustrates the differential height or thickness between the various zones of the absorbent structure 108. The retaining zone 110 has a total height or thickness of the areas of zones (excluding depressions recorded) in the Z direction. This dimension can be substantially constant (not variant) or it can vary in the X and Y directions from the center point (0,0,0) of the retention area depending on the density gradient in the respective X directions. Y. The surrounding storage area 126 also has a total height of the areas of zones (excluding any depressions) in the Z direction that can vary in dimensions X and / or Y or can be substantially constant, and may be greater than the corresponding height of the retention area 110. In a particular embodiment, the minimum height of the storage area 126 is equal to or greater than the maximum height in the retention area 110. The protection zones 118 they have a total height in the Z direction that can vary or can be substantially constant in the X and / or Y directions, and can be greater than the corresponding total height of the storage areas 126. In a particular embodiment, the minimum height of the protection zones 118 is equal to or greater than the maximum height in the storage areas 126. Therefore, it should be understood that, the respective heights in the dimension Z may generally increase in a gradual manner or in steps as one moves upwards from a point in the center of the holding area 110 in the X and Y directions.

Figure 14 illustrates a bottom view of an absorbent core material 140 that can be used alone or in combination with another material such as the absorbent structure in an article according to the invention. The absorbent core material 140 has a bottom surface 142 that is disposed toward the cover when the core material 140 is disposed in an absorbent article 100. In this particular embodiment, the absorbent core material 140 includes a plurality of densified regions 146. on the lower surface 144. These densified regions 146 may define any manner of series or patterns of such regions, such as a series of separate spaced depressions separated by raised edges or the like. The densified regions 146 can be defined by conventional mechanical means, such as recording. In the embodiment of Figures 14 and 15, the pattern of the densified regions 146 is defined between a series of spaced apart edges that extend generally along the entire length of the absorbent core. In alternative embodiments, the densified regions 146 can be delineated by either engraved channels 128 or 130 defined on the upper surface 142 of the absorbent core material. The densified regions may be etched or otherwise defined in the X and / or Y directions and have a width dimension of between about 0.2 millimeters to 5.0 millimeters with a range spaced from about 1 millimeter to about 10 millimeters. With reference to Figure 15, the dimension Y of the densified regions 146 may coincide with the peripheral outer channel 130 which defines the protection zones 118. The channel 130 may serve as a conduit for distributing fluid to the densified regions 146 for a further rapid absorption of fluid in the absorbent core material. The densified regions 146 defined on the bottom surface 144 of the core material 140 can also serve to prevent agglomeration of the absorbent core when compressed laterally. This feature can also serve to generate the M-shaped profile of article 100, as described above.

It should be appreciated that one aspect of the invention includes the incorporation of the densified regions 146 described above in any manner of construction of the core of the absorbent article without regard to any other feature. For example, an absorbent article 100 incorporating the densified regions 146 may or may not include a retention region having a density gradient as described above, or any other features described above.

It should be readily appreciated that various materials are known to those skilled in the art to use as the absorbent core material 140. A particularly desirable incorporation of core material 140 comprises a homogeneous mixture of cellulose fluff and super absorbent particles (SAP ). This composition can be maintained throughout the first lower base weight region 116 and the second higher base weight region 120. The super absorbent particles (SAP) are desirably evenly distributed throughout the first and second regions. In certain embodiments, the absorbent core material 140 may have a total cellulose fluff content of between about 2.5 grams and 5.0 grams, and a total super absorbent particle content of between about 0.2 grams and 0.4 grams. Several commercially available super absorbent particle compositions are well known to those skilled in the art and need not be described in detail here. It should also be appreciated that the invention encompasses concentrations of super absorbent particles (SAP) significantly greater, or less than, the ranges set forth above.

As mentioned, the absorbent structure 108 can include any conventional acquisition manner or take-up layer 148. Desirably, this acquisition layer 148 is disposed below the cover material 102 and overlays at least a substantial portion of the surface area of the retaining area 110, as illustrated for example in Figure 15. Suitable materials are known in the art. to rapidly take up and distribute fluids and any manner or combination of such materials can be used as the acquisition material layer 148. Such materials generally have a relatively low density (eg, less than the underlying absorbent material) for this purpose. Thus, the use of an acquisition or take-up layer 148 can provide a total density gradient in the Z direction by the overlay of the densest retention zone 110. The acquisition layer 148 can also be etched with the core material 140 in defining the retention area 110. In this manner, the acquisition layer 148 can also have a varying density gradient in the X and Y dimensions.

It should be appreciated by those skilled in the art that various modifications and variations can be made to the modifications described and illustrated herein without departing from the scope and spirit of the invention. It is the intention that the invention include these changes and others as they come within the scope and spirit of the appended claims.

The present invention is described in terms of specific techniques thereof, however certain variations will be considered to be obvious to a person skilled in the art, the same being within the scope of the present invention.

Claims (74)

R E I V I N D I C A C I O N S

1. An absorbent article which comprises a partially permeable cover; an absorption / retention layer having a density gradient in the Y direction and in the X direction, said density gradient being in a range of about 0.06 grams per cubic centimeter to 0.20 grams per cubic centimeter, or any other density value with an absorption area; a waterproof cover; a removable strip and multiple adhesive layers.

2. The absorbent article as claimed in clause 1 characterized in that the partially permeable cover is partially treated with a surfactant.

3. The absorbent article as claimed in clauses 1 or 2 characterized in that the partially permeable cover has a central hydrophilic zone of a length in a range of from about 35 mm to 65 mm.

4. The absorbent article as claimed in clauses 1, 2 or 3 characterized in that the partially permeable cover has a central hydrophilic zone not exceeding approximately 70% of the total area of the absorbent article.

5. The absorbent article as claimed in clauses 1, 2, 3 or 4 characterized in that the absorbent article may contain an acquisition layer.

6. The absorbent article as claimed in clause 5 characterized in that the acquisition layer generates a density gradient in the Z direction.

7. The absorbent article as claimed in clauses 5 or 6 characterized in that the acquisition layer has a density in a range from about 0.03 grams per cubic centimeter to about 0.09 grams per cubic centimeter.

8. The absorbent article as claimed in clauses 5, 6 or 7, characterized in that the acquisition layer consists of soft fibers comprising approximately 85% of cellulose pulp fibers and approximately 15% of polypropylene / polypropylene fibers of two-component or any other composition of material that serves the same purpose or use.

9. The absorbent article as claimed in clauses 5, 6 or 7, characterized in that the acquisition layer consists of a non-woven fabric composed of approximately 50% polypropylene / polypropylene bicomponent fibers and approximately 50% fibers of polyester, or any other composition of material serving the same purpose or use.

10. The absorbent article as claimed in clauses 5, 6, 7, 8 or 9 characterized in that the acquisition layer has a width which can be in a range of approximately 30 millimeters to approximately 50 millimeters, and a length of which can be in a range from approximately 50 millimeters to the total length of the finished product.

11. The absorbent article as claimed in clause 1 characterized in that the absorption / retention layer includes soft cellulose pulp fibers.

12. The absorbent article as claimed in clauses 1 or 11 characterized in that the absorption / retention layer contains a super absorbent polymer.

13. The absorbent article as claimed in clauses 1, 11 or 12 characterized in that the absorption / retention layer contains an absorbent paper.

14. The absorbent article as claimed in clause 12 characterized in that the super absorbent polymer is sodium acrylate.

15. The absorbent article as claimed in clauses 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14 characterized in that the absorption / retention layer has an hourglass shape and a minimum width in a range of about 42 millimeters to about 75 millimeters in the center and a maximum length in a range of about 60 millimeters to approximately 85 mm in the lobes.

16. The absorbent article as claimed in clauses 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, characterized in that the absorption / retention layer comprises two zones: a retention zone and a protection zone.

17. The absorbent article as claimed in clause 16 characterized in that the retention zone has a density gradient in a range of about 0.08 grams per cubic centimeter to about 0.20 grams per cubic centimeter, preferably in a range of about 0.10 grams per cubic centimeter at approximately 0.14 grams per cubic centimeter.

18. The absorbent article as claimed in clauses 16 or 17 characterized in that the protection zone has a density in a range of about 0.04 grams per cubic centimeter to about 0.10 grams per cubic centimeter, the preferred density being in a range of approximately 0.07 grams per cubic centimeter to approximately 0.08 grams per cubic centimeter.

19. The absorbent article as claimed in clauses 16, 17 or 18, characterized in that the difference between the density in the center of the retention zone and the density of the protection zone is a minimum of approximately 0.02 grams per cubic centimeter .

20. The absorbent article as claimed in clauses 16, 17, 18 or 19, characterized in that the protection zone comprises a channel engraved in a racetrack or hourglass format.

21. The absorbent article as claimed in clauses 16, 17, 18, 19 or 20, characterized in that the retention area represents a maximum of approximately 60% of the absorption / retention layer.

22. The absorbent article as claimed in clauses 16, 17, 18, 19, 20 or 21 characterized in that the retention area has a thickness that is in a range of about 1.5 millimeters to about 3.5 millimeters.

23. The absorbent article as claimed in clauses 16, 17, 18, 19, 20, 21 or 22 characterized in that the maximum density is constant over a length of about 20 millimeters to about 200 millimeters in the direction (X) and about a width of about 15 millimeters to about 40 millimeters in the direction (Y).

24. The absorbent article as claimed in clauses 16, 17, 18, 19, 20, 21, 22 or 23 characterized in that increasing the distance from the center of the absorbent article in the direction (Y) reduces the density, creating a capillary gradient and a fluid distribution gradient, achieving a minimum density of approximately 0.08 grams per cubic centimeter in the limits of the retention area.

25. The absorbent article as claimed in clauses 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 , 21, 22, 23 or 24 characterized in that the density gradients are obtained in a mechanical manner, lying on a homogeneous absorption / retention layer having the same amount of absorbent material distributed through the area thereof.

26. The absorbent article as claimed in clause 25 characterized in that the density gradients are obtained by means of engraving pins of different heights from the center to the edges, with the largest bolt height in the center of the absorbent article.

27. The absorbent article as claimed in clauses 25 or 26 characterized in that the height decreases with increasing distance from the center; the difference in height from one area of bolts to the next area may be in a range of about 0.01 millimeters to about 1 millimeter, preferably from about 0.3 millimeters to about 0.6 millimeters.

28. The absorbent article as claimed in clauses 25, 26 or 27 characterized in that the density gradients are obtained by means of engraving pins with different areas of compression, with the largest area in the center and the smaller areas in more distant locations from the center; the area of each compression can be in a range of about 1 millimeter square to about 16 millimeter square in the center, preferably from about 2 square millimeters to 4 square millimeters, being from about 0.01 square millimeters to about 2 square millimeters in the external part of the retention area, preferably being from approximately 0.8 square millimeters to 1.5 square millimeters.

29. The absorbent article as claimed in clauses 25, 26, 27 or 28 characterized in that the engraving pins define engraved regions having any of the following shapes: diamond, square, perpendicular lines, diagonal lines, sinusoidal lines, shape of polygon, circular, triangular and other patterns or shapes.

30. The absorbent article as claimed in clauses 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 or 29, characterized in that the protection zone comprises a region of a density constant surrounding the retention zone and representing the maximum of approximately 40% of the absorption / retention layer.

31. The absorbent article as claimed in clauses 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 characterized in that the protection zone has a thickness in a range of about 2.5 millimeters to about 8 millimeters, preferably from about 4 millimeters to about 7 millimeters.

32. The absorbent article as claimed in clauses 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or 31 characterized in that the protection zone has a lower capillarity of the absorption / retention layer being located below a hydrophobic area of the nonwoven cover.

33. The absorbent article as claimed in clauses 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 or 32, characterized in that the protection zone it may contain different channel designs, in terms of shape, length and quantity being areas of mechanically compressed material.

34. The absorbent article as claimed in clauses 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32 or 33 characterized in that the combination of the engraving of the retention area and of the channels in the protection zone imparts an "M" type shape in use.

35. The absorbent article as claimed in clauses 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 or 34 characterized in that it also comprises absorbent side barriers.

36. The absorbent article as claimed in clause 35 characterized in that the absorbent side barriers are located on at least one of the sides of the acquisition layer, below the hydrophobic area of the treated deck area and lying on the area of protection of the absorption / retention layer.

37. The absorbent article as claimed in clauses 35 or 36 characterized in that the side barriers comprise a super absorbent material applied in at least one line on at least one of the sides of the absorbent article as a hot-release adhesive, said super absorbent line having a width in a range of about 0.5 millimeters to about 10 millimeters, preferably from about 3 millimeters to about 7 millimeters, and a length in a range of about 30 millimeters to about 300 millimeters, preferably from approximately 40 millimeters to approximately 60 millimeters.

38. The absorbent article as claimed in clause 35, 36 or 37 characterized in that the side barriers have a concentration which may be in a range from about 0.05 grams / side to about 5 grams / side, preferably from 0.1 gram / side at 0.3 grams / side.

39. The absorbent article as claimed in clause 35 or 36, characterized in that the lateral barriers comprise a material of air-laid type containing the super absorbent in the composition thereof, said material being applied in at least one strip on the at least one of the sides of the absorbent article; said super absorbent strip having a width in a range of about 3 millimeters to about 10 millimeters, and a length in a range of about 30 millimeters to about 300 millimeters, preferably from about 40 millimeters to about 60 millimeters.

40. The absorbent article as claimed in clause 39 characterized in that the side barriers have a basic weight in a range of from 100 grams per square meter to 500 grams per square meter.

41. The absorbent article as claimed in clauses 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 , 36, 37, 38, 39 or 40 characterized in that the combination of the retention area and the protection zone in the absorption / retention layer also exhibits a thickness gradient in the product, the last thickness being obtained in the center of the absorbent article in the retention area and the largest thickness in the protection zone.

42. The absorbent article as claimed in clauses 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 , 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 or 41 characterized because generally the point 0,0 , 0 represents the maximum product density and said density decreases along the X, Y and Z axes, achieving their minimum values in the protection zone (X, Y directions) and in the acquisition layer (Z direction).

43. A method of manufacturing an absorbent article which comprises the steps of: the provision of a cover sheet, an absorption / retention layer, and a bottom sheet each having side and longitudinal edges; laminating the absorption / retention layer to the cover sheet and the lower sheet so that the absorption / retention layer is placed between the cover sheet and the lower sheet; Y obtaining a density in a mechanical manner, in the laminated cover sheet, and in the absorption / retention layer in both X and Y directions, so that there is a density gradient that generally decreases from the center of the sheet of cover to the lateral and longitudinal edges of the article.

44. The method as claimed in clause 43 characterized in that it also comprises the following steps: the provision of an acquisition layer; laminating the acquisition layer between the cover sheet and the lower sheet before the density obtaining phase in a mechanical manner, so that the acquisition layer also obtains a density in a mechanical manner; wherein the layers in which a density is obtained in a mechanical manner provide a generally decreased density gradient from the center of the cover sheet to the lateral and longitudinal edges of the article.

45. The method as claimed in clauses 43 or 44 characterized in that the step of obtaining density in a mechanical manner includes engraving with bolts.

46. The method as claimed in clause 43, 44 or 45, characterized in that it also comprises the steps of applying side barriers on one or more of the sides of the absorbent article.

47. An absorbent article comprising: a liquid permeable cover; a separator material; an absorbent structure positioned between said cover and said spacer material, said absorbent structure comprising a retention zone having a variable density gradient in a dimension X defined in a first region of said absorbent structure having a first basis weight, and a protection zone having a substantially uniform density less than a minimum density of said density gradient in said retention zone and defined in a second region of said absorbent article having a second basis weight that is greater than said first basis weight, said protection zone defined longitudinally along the opposite lateral sides of said absorbent structure.

48. The absorbent article as claimed in clause 47 characterized in that the protection zone has a height in the Z-dimension greater than said retaining zone.

49. The absorbent article as claimed in clauses 47-48 characterized in that said absorbent structure further comprises a storage area defined at the opposite longitudinal ends of said retention area, said storage zone having a density that is less than a density minimum of said density gradient in said retention zone and greater than said density of said protection zone.

50. The absorbent article as claimed in clause 49, characterized in that said storage area is defined in said region of said absorbent structure having said first basis weight.

51. The absorbent article as claimed in clause 50 characterized in that said storage zone comprises a minimum Z-dimension height that is equal to or greater than a maximum Z-dimension height of said retention area and equal to or less than a minimum Z-dimension height of said protection zone.

52. The absorbent article as claimed in clause 49, characterized in that said storage area surrounds said retention area.

53. The absorbent article as claimed in clause 52, characterized in that it also comprises an engraved channel delimiting said retaining area of said storage area.

54. The absorbent article as claimed in clause 52 characterized in that said storage zone extends to the transverse and longitudinal ends of said absorbent structure.

55. The absorbent article as claimed in clause 53, characterized in that it also comprises an engraved channel delimiting said storage area of said protection zone.

56. The absorbent article as claimed in clause 49, characterized in that it comprises at least one transverse engraved channel defined in said spaced storage area of each opposite longitudinal end of said retaining zone.

57. The absorbent article as claimed in any of clauses 47-56 characterized in that said retention zone extends laterally to said protection zone.

58. The absorbent article as claimed in any of clauses 47-57 characterized in that said retention area is surrounded by a storage area and further comprises an internal engraved channel that delimits said retention area and said storage area and a channel external engraving that delimits said protection zone and said storage area.

59. The absorbent article as claimed in clause 58 characterized in that said storage zone extends to the transverse ends of said absorbent structure.

60. The absorbent article as claimed in clause 58 characterized in that said storage area comprises a substantially uniform basis weight and an essentially uniform density.

61. The absorbent article as claimed in clause 58 characterized in that said storage zone comprises a substantially constant Z-dimension height greater than a maximum Z-dimension height of said retaining zone and less than a Z-dimension height. essentially constant of said protection zone.

62. The absorbent article as claimed in any of clauses 47-61 characterized in that said retention zone further comprises a gradient of variable density in the dimension Y.

63. The absorbent article as claimed in any of clauses 47-62 characterized in that said variable density gradient in said retaining zone is defined by a variable depth engraving pattern.

64. The absorbent article as claimed in any of clauses 47-63 characterized in that said variable density gradient in said retaining zone is defined by a variable surface area engraving pattern.

65. The absorbent article as claimed in any of clauses 47-62 characterized in that said variable density gradient in said retention zone is defined by a combination of a variable surface area and varying depth engraving pattern.

66. The absorbent article as claimed in any of clauses 47-65 characterized in that said absorbent structure comprises cellulosic fluff and a super absorbent particle composition (SAP), said first region comprises a basis weight of between 230 grams per square meter and 500 grams per square meter, and a second region comprises a basis weight of between 400 grams per square meter and 800 grams per square meter.

67. The absorbent article as claimed in clause 66 characterized in that said absorbent structure comprises a total waste content of between 2.5 grams and 5.0 grams and an SAP content of between 0.2 grams and 0.4 grams.

68. The absorbent article as claimed in clause 66 characterized in that said retention zone has a density gradient of from about 0.20 grams / cubic centimeter to about 0.08 grams / cubic centimeter, and wherein said protection zone has a essentially uniform density with a differential density of between a maximum density of said retention zone and said protection zone of at least about 0.02 grams / cubic centimeter.

69. The absorbent article as claimed in clause 68 characterized in that said absorbent structure further comprises a storage area generally surrounding said retaining area, said storage area having an essentially uniform basis weight less than said protection zone and a density essentially uniform smaller than a minimum density of said retention zone and greater than said protection zone.

70. The absorbent article as claimed in clause 69 characterized in that said protection zone comprises a height in the Z-dimension, said retaining zone comprises a maximum height in the Z-dimension smaller than said protection zone, and said zone storage comprises a height in the Z-dimension greater than said maximum height of said retaining area and less than said protection zone.

71. The absorbent article as claimed in any of clauses 47-70 characterized in that said absorbent structure comprises an absorbent core material having said retention zone and said protection zone defined therein, and a layer of acquisition material that lies on At least said retaining zone, said layer of acquisition material provides a density gradient of the Z-dimension to said absorbent structure.

72. The absorbent article as claimed in any of clauses 47-71 characterized in that said absorbent structure comprises an absorbent core material having an upper surface positioned toward the cover, and a lower surface positioned towards the separator, and further comprises a plurality of spaced and spaced densified regions defined in said lower surface of said absorbent core.

73. The absorbent article as claimed in clause 72 characterized in that said densified regions are defined by a pattern of engraved cross-sectional regions.

74. The absorbent article as claimed in clause 73 characterized in that said pattern of engraved regions extends generally along the entire length of said absorbent core. SUMMARY An absorbent article includes a liquid permeable cover, a spacer material, and an absorbent structure positioned between the cover and the spacer material. The absorbent structure includes a retention zone having a variable density gradient in at least two dimensions and a protection zone having a part with a density less than the minimum density of the density gradient in the retention zone. The retention zone may be defined in the first region of the absorbent structure having a first basis weight and the protection zone may be defined in a second region of the absorbent structure having a second basis weight that is greater than the first basis weight.