Patent Description:
The disposable absorbent articles are articles which are used in proximity with the skin of a wearer to absorb and retain body exudates; they are basically constituted by an upper liquid-pervious topsheet, a bottom liquid impervious backsheet and an absorbent core disposed between them. The absorbent core of this kind of articles is generally composed of fibers of absorbent material and / or particles of superabsorbent material; its main functions are to absorb and to retain liquid or semi-liquid exudates from the human body that penetrate through the upper layer of the article. For the absorbent core being effective, it needs to have a good integrity, that is to say, the absorbent core must maintain its structure and does not break or collapse either in a dry or in a wet state. If said absorbent core breaks, its absorption and retention capacity is lost and it is not capable of distributing the fluids properly causing leakage, agglomerations of absorbent material and discomfort to the wearer. Multiple attempts have been made to prevent or minimize the structural breaks of the absorbent cores such as the use of nets, adhesives, core wraps, embossing and others. On the other hand, for an absorbent core having a good functionality, the fluids must be distributed properly along it in order to use its full absorbent capacity; it is also relevant that the fluids penetrate into the absorbent core as quickly as possible in order to preserve the health of the skin of the wearer.

There are some patents focused on improving the integrity of the absorbent cores, for example the <CIT> and <CIT>) which disclose a stabilized absorbent composite web and the method for producing it; said absorbent composite comprises a first sheet joined to a second sheet through a plurality of holes formed in the absorbent core. These patents are fully focused on improving the integrity of the absorbent core sacrificing the ability to absorb liquids more quickly as well as the ability to distribute them more evenly and efficiently through the absorbent core.

On the other hand, there are several patents focused in improving the distribution of fluids in the absorbent core using channels. For example the patents listed below refer to absorbent articles comprising an absorbent core with an upper core wrap, a lower core wrap, a fibrous layer and one or more areas free of absorbent material through which the upper core wrap joins to the lower core wrap, such that when the absorbent material swells, the core wrap forms channels along the areas free of absorbent material; these channels also help for having a good rate of absorption of fluids into the core: <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>.

<CIT> from Procter & Gamble refers to an absorbent core comprising a core wrap enclosing superabsorbent particles: the superabsorbent particles form a pattern of dot-shape discrete areas which can be oriented longitudinally or transversely; these areas are separated from each other by areas substantially free of material.

<CIT>) describes an absorbent core with first and second longitudinal channels free of absorbent material; the core may further comprise one or more transverse oriented folding lines in which the basis weight of absorbent material reaches a minimum relative to the immediately adjacent regions.

The present invention addresses the technical problems described above and provides an absorbent article with an absorbent assembly with improved integrity which also improves the absorption rate, the rewet and the distribution of fluids inside it, expressed as the percentage of use of the absorbent core, said absorbent article having the features of claim <NUM>. The at least one connecting line participates for improving the distribution of fluids in the absorbent core. By combining in an absorbent assembly the cavities substantially free of absorbent material, the at least one connecting line interconnecting them and the permanent bonding between the upper and lower core wraps, the resulting absorbent assembly may show all together a very good integrity, a very good distribution of fluids a quick rate of absorption and a low rewet.

The present invention relates to a disposable absorbent article having a longitudinal direction and a transverse direction, the absorbent article comprising a liquid-pervious topsheet, a liquid-impervious backsheet and an absorbent assembly disposed between the topsheet and the backsheet. The absorbent assembly has two longitudinal edges, two transverse edges, a wearer-facing surface, a garment-facing surface, a longitudinal central axis extending along a length of the absorbent assembly and a transverse central axis defining a front portion and a back portion. The absorbent assembly comprises an absorbent core, an upper core wrap and a lower core wrap. The upper core wrap is a hydrophilic nonwoven web having a basis weight between <NUM>/m<NUM> and <NUM>/m<NUM>. The lower core wrap is a hydrophobic or a hydrophilic nonwoven web having a basis weight between <NUM>/m<NUM> and <NUM>/m<NUM>.

The absorbent core comprises absorbent material comprised by a mixture of superabsorbent polymer and cellulosic fibers. It further comprises at least two cavities substantially free of absorbent material having a width with respect to the transverse central axis and a length with respect to the longitudinal central axis. Said cavities are interconnected via at least one connecting line having a width with respect to the transverse central axis and a length with respect to the longitudinal central axis. The at least one connecting line comprises absorbent material. The absorbent core has a first basis weight in the zone out of the cavities and the connecting lines and a second basis weight in the connecting lines, the first basis weight being greater than the second basis weight. The upper core wrap and the lower core wrap are permanently attached to each other in the cavities.

In an embodiment of the invention, the at least two cavities of the absorbent core may be aligned on the longitudinal central axis of the absorbent assembly and be interconnected via at least one longitudinal connecting line substantially parallel to the longitudinal central axis. In an alternative embodiment of the invention, the cavities of the absorbent core may form a pattern comprising two rows of at least two cavities, the cavities of each row being longitudinally interconnected via at least one longitudinal connecting line substantially parallel to the longitudinal central axis, each row being disposed on each side of the longitudinal central axis. Both these patterns may provide particularly advantageous integrity, distribution of fluids and quick rate of absorption.

All the terms used to define the elements and / or features of the present invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Embodiments of articles according to the present invention will now be described, from here on, in relation to a disposable diaper, but it is understood that the absorbent article may be selected from disposable diapers, disposable adult pants, disposable baby pants, adult incontinence pads, sanitary napkins and the like. The technical features described in one or more embodiments may be combined with one or more other embodiments without departing from the intention of the disclosure and without generalization thereof.

<FIG> illustrates a wearer facing surface of a disposable absorbent article (<NUM>) according to an embodiment of the present invention in an extended configuration. As can be seen, the disposable absorbent article (<NUM>) comprises basically a liquid-pervious topsheet (<NUM>), a liquid-impervious backsheet (<NUM>) and an absorbent assembly (<NUM>) placed between them. The disposable absorbent article comprises two opposite longitudinal sides and two opposite transverse sides; the disposable absorbent article (<NUM>) can also contain a fastening system, leg and waist elastic zones, front and back ears, transfer layers, containment barriers and other elements well known in the art.

<FIG> shows a transverse cross-section of the disposable absorbent article of <FIG> taken along the transverse central axis (X-X). The disposable absorbent article (<NUM>) comprises a liquid-pervious topsheet (<NUM>), an absorbent assembly (<NUM>) and a backsheet (<NUM>); the absorbent assembly (<NUM>) is constituted by an upper core wrap (<NUM>), an absorbent core (<NUM>) and a lower core wrap (<NUM>).

The absorbent assembly (<NUM>) has two longitudinal edges (<NUM>, <NUM>'), two transverse edges (<NUM>, <NUM>'), a wearer-facing surface (<NUM>), a garment-facing surface (<NUM>), a longitudinal central axis (Y-Y) and a transverse central axis (X-X). The longitudinal central axis (Y-Y) extends along the length of the absorbent assembly (<NUM>) so that it defines a left side and a right side, each one of said sides having a substantially equal transverse width; the transverse central axis (X-X) extends along the width of the absorbent assembly (<NUM>) defining a front portion (<NUM>) and a back portion (<NUM>), each one of said portions having a substantially equal length. The absorbent core (<NUM>) of the invention comprises at least two cavities (<NUM>) and at least one connecting line (<NUM>) interconnecting them.

Said absorbent core (<NUM>) is comprised of absorbent material which is composed preferably of a mixture of superabsorbent polymer particles (SAP) and cellulosic fibers which could be replaced by other fibers of absorbent material of natural or synthetic origin. The superabsorbent polymer particles are able to absorb and retain fluids many times their own weight and may be in the form of particles, fibers, flakes or the like.

The cavities (<NUM>), as are shown for example in <FIG>, are substantially free of absorbent material and have a width (W1) in transverse direction and a length (L1) in longitudinal direction.

Advantageously, cavities according to the invention may have an area between <NUM><NUM> and <NUM><NUM>, preferably between <NUM><NUM> and <NUM><NUM>, more preferably between <NUM><NUM> and <NUM><NUM>.

Preferably, the cavities (<NUM>) of the invention are longitudinally spaced from each other by a distance between <NUM> and <NUM>, more preferably between <NUM> and <NUM>, even more preferably between <NUM> and <NUM> or between <NUM> and <NUM>. Advantageously, they are transversely spaced from each other by a distance between <NUM> and <NUM>, more preferably between <NUM> and <NUM>, even more preferably between <NUM> and <NUM> or between <NUM> and <NUM>. These distances between the cavities corresponds to the shortest distance between the perimeter of one cavity and the perimeter of the next cavity in longitudinal or transverse direction. The distance in longitudinal direction between two neighboring cavities (<NUM>) may correspond to the length (L2) of a connecting line (<NUM>).

In a preferred embodiment, the cavities (<NUM>) have a circular shape but alternatively, they may have a shape selected from the group consisting of triangles, squares, rectangles, polygons, ovals, semicircles, arrows, crosses, irregular shapes and combinations thereof.

As the upper and lower core wraps are permanently attached in these cavities, the absorbent material between each cavity is immobilized thereby helping in maintaining the integrity of the absorbent core (<NUM>). These dimensions and shapes have proven to help in providing this integrity.

One function of the at least one connecting line (<NUM>) is to spread or distribute the fluids effectively throughout the absorbent core (<NUM>), thereby helping in increasing the absorption rate and better using all the absorption capacity of the absorbent core. Each connecting line has a width (W2) with respect to the transverse direction and a length (L2) with respect to the longitudinal direction, as can be seen in <FIG>. The ratio (W2/W1) between the transverse width of the connecting line (W2) and the transverse width of the cavities substantially free of absorbent material (W1) is preferably at most <NUM>, more preferably at most <NUM>, even more preferably at most <NUM>, so that when a fluid reaches a cavity, it passes quickly through the connecting line(s) directly to another cavity helping in distributing the fluid in the absorbent core.

The absorbent core (<NUM>) of the present invention has a first basis weight (bw1) outside the cavities (<NUM>) and the connecting line (<NUM>), and a second basis weight (bw2) in the connecting line (<NUM>). The first basis weight (bw1) is greater than the second basis weight (bw2). Preferably, the ratio (bw2/bw1) between the second basis weight (bw2) and the first basis weight (bw1) is between <NUM> and <NUM>, more preferably between <NUM> and <NUM>, even more preferably between <NUM> and <NUM>. These ratios are advantageous in that the fluid may be transported more quickly in the areas having less basis weight. For this reason, the distribution of fluid inside the absorbent core (<NUM>) of the present invention may be improved compared with the distribution of fluids in an absorbent core (<NUM>) having a constant basis weight. In addition, as the fluid is better distributed, it does not accumulate in small zones and as a result of this, the rewet may be lowered. On the other side, the cavities (<NUM>) in conjunction with the connecting line (<NUM>) may help for the absorbent assembly (<NUM>) having a fast rate of absorption and / or in directing the fluid in order to use all the absorption capacity of the core (<NUM>).

In preferred embodiments of the present invention, the upper core wrap (<NUM>) is permanently attached to the lower core wrap (<NUM>) in the cavities (<NUM>) by means of adhesive, thermal bonding, pressure bonding, mechanical bonding, ultrasonic bonding or combinations thereof or any other means known in the art. The permanent attachment between the upper core wrap (<NUM>) and the lower core wrap (<NUM>) in the cavities (<NUM>) defines bonding zones (<NUM>), as can be seen in <FIG> which may contribute to the absorbent assembly (<NUM>) having a very good integrity given that the absorbent material is immobilized between the cavities (<NUM>). The upper core wrap and lower core wrap (<NUM>, <NUM>) are preferably nonwoven webs made from natural or synthetic fibers and/or combinations thereof; they can be composed of one or more layers bonded together and can be manufactured by any known method. According to the present invention, the upper core wrap (<NUM>) is a hydrophilic nonwoven web having a basis weight between <NUM>/m<NUM> and <NUM>/m<NUM> and the lower core wrap (<NUM>) is a hydrophobic or a hydrophilic nonwoven web having a basis weight between about <NUM>/m<NUM> and <NUM>/m<NUM>.

In an embodiment of the present invention shown in <FIG>, nine cavities (<NUM>) are aligned on the longitudinal central axis (Y-Y) of the absorbent assembly (<NUM>), and are interconnected via at least eight longitudinal connecting lines (<NUM>), said connecting lines (<NUM>) being on the longitudinal central axis (Y-Y).

Another embodiment of the present invention is shown in <FIG>. In this embodiment, six cavities (<NUM>) have an arrow-shape and are aligned on the longitudinal central axis of the absorbent assembly (<NUM>), such that, the arrow-shaped cavities (<NUM>) point toward the transverse edges of the absorbent assembly (<NUM>). Said cavities (<NUM>) are interconnected through five longitudinal connection lines (<NUM>) on the longitudinal central axis (Y-Y).

<FIG> shows another embodiment of the present invention in which the cavities (<NUM>) are disposed in the absorbent core (<NUM>) forming a pattern, said pattern comprising two rows of two cavities (<NUM>) being interconnected via one longitudinal connecting lines (<NUM>). Each row is disposed on each side of the longitudinal central axis (Y-Y) of the absorbent assembly (<NUM>) and parallel to it. The connecting lines (<NUM>) are substantially parallel to the longitudinal central axis (Y-Y).

<FIG> shows another embodiment of the present invention in which the cavities (<NUM>) form a pattern comprising four rows. Each row comprises at least two cavities (<NUM>) interconnected via at least one connecting line (<NUM>), one row being disposed in the front right quarter of the absorbent assembly (<NUM>), the second one being disposed in the front left quarter of the absorbent assembly (<NUM>), the third one in the back right quarter of the absorbent assembly (<NUM>) and the fourth row in the back left quarter of the absorbent assembly (<NUM>) respectively. The first row is interconnected
to the fourth row via at least one connecting line (<NUM>) and the second row is interconnected to the third row via at least one connecting line (<NUM>), such that, these connecting lines (<NUM>) form an X-shaped pattern.

<FIG> shows another embodiment of the present invention in which, the cavities (<NUM>) are disposed in the absorbent core (<NUM>) forming a hexagonal pattern, said hexagonal pattern comprising six cavities (<NUM>) coinciding with the apex of the hexagonal pattern, and a plurality of connecting lines (<NUM>) connecting the cavities (<NUM>) such that, the connecting lines (<NUM>) define the outer perimeter of the hexagonal pattern.

In some embodiments of the invention, one or more connecting lines (<NUM>) may comprise regions having the second basis weight (bw2) and other regions having a third basis weight (bw3), so that the first basis weight (bw1) is greater than the second basis weight (bw2), and the second basis weight (bw2) is greater than the third basis weight (bw3). In this way the fluid may run in the connecting lines at varying speed, helping the absorbent assembly (<NUM>) to be more efficient in the rate of absorption and in the distribution of fluids.

The cavities (<NUM>) may be distributed in the absorbent core forming any pattern. As the discharge of fluids into the absorbent article is made generally in the front portion (<NUM>) of the absorbent assembly (<NUM>), this front portion (<NUM>) is the one that tends to first loss the integrity, thereby losing its capability to absorb and distribute the fluids. Therefore, in a preferred embodiment, more than <NUM>% of the total area of the cavities (<NUM>) is disposed in the front portion of the absorbent assembly (<NUM>). The total area of the cavities is obtained by adding the individual area of each cavity (<NUM>).

The saline solution should be prepared <NUM> hours before the test; its shelf life is up to <NUM> days.

Embodiment A (not according to the invention): Disposable absorbent baby diaper size "L" containing an absorbent assembly comprising:.

Embodiment B (according to the invention): Disposable absorbent baby diaper size "L" containing an absorbent assembly comprising:.

Embodiment C (according to the invention): Disposable absorbent baby diaper size "L" containing an absorbent assembly comprising:.

Table <NUM> shows the results obtained for the three embodiments A, B, C.

Claim 1:
A disposable absorbent article (<NUM>) having a longitudinal direction and a transverse direction, the absorbent article comprising:
▪ a liquid-pervious topsheet (<NUM>),
▪ a liquid-impervious backsheet (<NUM>) and
▪ an absorbent assembly (<NUM>) disposed between the topsheet (<NUM>) and the backsheet (<NUM>) and having two longitudinal edges (<NUM>, <NUM>'), two transverse edges (<NUM>, <NUM>'), a wearer-facing surface (<NUM>), a garment-facing surface (<NUM>), a longitudinal central axis (Y-Y) extending along a length of the absorbent assembly (<NUM>) and a transverse central axis (X-X) defining a front portion (<NUM>) and a back portion (<NUM>), the absorbent assembly (<NUM>) comprising:
- an absorbent core (<NUM>),
- an upper core wrap (<NUM>) which is a hydrophilic nonwoven web having a basis weight between <NUM>/m<NUM> and <NUM>/m<NUM> and
- a lower core wrap (<NUM>) which is a hydrophobic or a hydrophilic nonwoven web having a basis weight between <NUM>/m<NUM> and <NUM>/m<NUM>,
wherein the absorbent core (<NUM>) comprises absorbent material comprised by a mixture of superabsorbent polymer and cellulosic fibers,
wherein the absorbent core (<NUM>) comprises at least two cavities (<NUM>) free of absorbent material having a width (W1) with respect to the transverse central axis (X-X) and a length (L1) with respect to the longitudinal central axis (Y-Y), said cavities (<NUM>) being interconnected via at least one connecting line (<NUM>) having a width (W2) with respect to the transverse central axis (X-X) and a length (L2) with respect to the longitudinal central axis (Y-Y), the at least one connecting line (<NUM>) comprising absorbent material,
wherein the absorbent core (<NUM>) has a first basis weight (bw1) in the zone out of the cavities (<NUM>) and the connecting lines (<NUM>), and a second basis weight (bw2) in the connecting lines, the first basis weight (bw1) being greater than the second basis weight (bw2), and
wherein the upper core wrap (<NUM>) and the lower core wrap (<NUM>) are permanently attached to each other in the cavities (<NUM>).