Sustainable absorbent article with fluid flow control structure

Abstract

Provided herein is an absorbent article comprising a liquid permeable topsheet (1), a liquid impermeable backsheet (4), an absorbent core (3) arranged between the topsheet (1) and the backsheet (4), and a fluid flow control structure (2) arranged between the topsheet (1) and the absorbent core (3), wherein the fluid flow control structure (2) comprises at least a first nonwoven layer (21) comprising natural materials such as regenerated cellulose, cotton, lyocell, kapok and / or hemp in an amount of at least 90% by weight of the first nonwoven layer (21), wherein the first nonwoven layer (21) is a three-dimensionally formed layer having a plurality of apertures (213) and comprising a stiffening member.

Description

Sustainable absorbent article with fluid flow control structureField of the invention

[0001] The present disclosure relates to absorbent articles, such as sanitary towels, panty liners, incontinence pads or diapers, which are made with sustainable materials and designed to accommodate a balance between efficient fluid handling and user comfort. In particular, these absorbent articles are configured to provide improved retention of absorbed fluid(s), to minimize the occurrence of surface wetness and / or rewet during use, and to further enhance wearer comfort and confidence in the articles.Background

[0002] Absorbent articles, such as sanitary napkins, panty liners, diapers, incontinence pads, and the like need to have good absorptive properties and should provide the wearer with a sense of security against leakage. Such absorbent articles are generally constructed with a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent structure arranged between the topsheet and the backsheet.

[0003] A typical topsheet, which is arranged on the user facing side of the absorbent article, may be formed from nonwoven material(s), apertured films, or combinations (e.g., non-woven / film composite or laminate). In contrast, backsheets, which are arranged on the garment facing side of the absorbent articles, are typically made of films, for example, a solid polymer film. In some cases, these films may even include breathable materials that do not impact the imperviousness of the backsheet to fluid leakage. Further, the absorbent structure(s), i.e. absorbent core, may be made from a variety of materials, including but not limited to pulp, other fibrous materials, superabsorbent particles or fibers, and combinations thereof.

[0004] One or more additional layers may be provided between the topsheet and the absorbent structure to further facilitate liquid handling, mainly intake and distribution, into and within the absorbent article. One example of such an additional layer is EP 2353562 A1 , which describes a composite suitable for use as a transfer layer, or acquisition distribution layer, in an absorbent article between the topsheet and the absorbent core to promote fluid distribution, reduce surface wetness in the topsheet, and reduce or eliminate rewet in general.

[0005] However, a vast majority of the disposable absorbent articles that are currently commercially available contain a significant amount of material(s) sourced from petrochemicals, such as petroleum-based fibers and petroleum-based polymers, usually in both the topsheet and backsheet layers. Not to mention, the absorbent core and / or additional layers typically contain synthetic superabsorbent polymers (SAP) which are also often derived from petroleum-based polymers or materials. These materials are not sustainable and contribute to an ever-growing waste stream of used absorbent articles that ultimately end up in traditional landfills. Thus, there is an existing demand for alternative solutions to remediate the impact of such absorbent articles on available resources and the environment.

[0006] In addition, conventional source materials, such as plastics, currently used in the manufacture of commercially available disposable absorbent articles possess certain desirable characteristics, including but not limited to breathability, processability, durability, and absorbent capacity (e.g., inlet performance and fluid retention) that are imparted to the absorbent articles. Sustainable materials must, therefore, provide these same characteristics in order to be acceptable substitutes; otherwise, consumers may lose confidence in or simply reject products containing the same.

[0007] Consequently, there remains a need to provide absorbent articles formed from sustainable materials that possess efficient fluid handling properties without sacrifice to user comfort. Relatively high retention of absorbed bodily discharge(s), security against leakage, and comfortability, particularly relating to a perceived feeling of dryness during use of the absorbent articles, are exemplary characteristics that are desirable to consumers and should at least be comparable to, if not improved over, those provided by the conventional plastic-based source materials typically found in disposable absorbent articles that are commercially available to date.Summary

[0008] Now more than ever there is a need to shift from the use of conventional source materials such as plastics in the manufacture of disposable absorbent articles to more sustainably-based and renewable source materials, such as non-plastics. However, absorbent article characteristics, including but not limited to efficient fluid handling and user comfort, that are highly desirable for consumers should not be diminished due to this shift. Rather, alternative solutions using sustainable material(s) should have such properties that are at least comparable, relative to those provided by absorbent articles manufactured using typical plastic-based source materials.

[0009] In addition, it has been found that despite prior art solutions for disposable absorbent articles, there is still a need to improve the fluid handling properties of such articles, especially with respect to fluid intake and retention within the absorbent article. In this regard, it is important that the absorbent articles are enabled to effectively capture and retain absorbed fluid(s) in a desired and predetermined manner, and by extension, prevent leakage therefrom. Not to mention, it is highly desirable that the absorbent articles provide the wearer with a continued sense of dryness during use of the article.

[0010] An objective of the present disclosure is thus to provide an absorbent article having efficient fluid handling properties that is also made using sustainable material(s). Further, it is desirable that the absorbent article be provided with improved performance and comfort. Incontinence shields and sanitary napkins are designed to have a total absorption capacity that is large enough to absorb all fluid that is expected to be released to the absorbent article during a period of wear. However, the fluid is normally not exuded in a steady flow but as sudden gushes of relatively large volume under pressure and during a very short time period. In this regard, the absorbent article should be enabled to manage a rapid rush of fluid discharged by the wearer, such as urine or menstrual blood, quickly and efficiently. More particularly, it is desirable that the absorbed fluid is able to quickly reach the absorbent core where it is efficiently distributed and securely retained.

[0011] In terms of fluid handling, it is desirable that the absorbent article is enabled to minimize the occurrence of surface wetness and / or rewet at any point during use. Further, it is desirable that the absorbent article has a relatively high level of retention of absorbed fluid(s) and that the thickness of the individual layers, especially the fluid flow control structure, is substantially maintained even when subjected to compressive forces normally exerted during use.

[0012] It is further desirable still to provide an absorbent article that is both discrete and comfortable to wear. Any one or more of the aforementioned properties may additionally contribute to and / or improve the comfort level of a user when wearing the absorbent article.

[0013] It is also an objective to provide an absorbent article in which leakage security is not reduced, if not all together unaffected.

[0014] Depending on the desired application, the absorbent articles described herein may take the form of any one of a sanitary towel, sanitary napkin, a panty liner, an incontinence pad, an incontinence liner or a diaper.

[0015] In the interest of sustainability, it may be even further desirable to provide an absorbent article that is partially reusable. Accordingly, waste can be further minimized since disposal of only the portion of the absorbent article that retains the fluids / exudates following use may be required.

[0016] The objectives set forth herein are achieved by the present absorbent article as defined in the appended claims.Accordingly, there is provided an absorbent article comprising a liquid permeable topsheet, a liquid impermeable backsheet, an absorbent core arranged between the topsheet and the backsheet, and a fluid flow control structure arranged between the topsheet and the absorbent core. The fluid flow control structure comprises at least a first nonwoven layer comprising natural materials such as regenerated cellulose, cotton, lyocell, kapok and / or hemp in an amount of at least 90% by weight of the first nonwoven layer. The first nonwoven layer is a three-dimensionally formed layer having a plurality of apertures and comprising a stiffening member. The stiffening member is an adhesive or other coating. The stiffening member may be derivable from a renewable resource. The amount of the stiffening member may be between 2.0 to 15.0 gsm.

[0017] Due in part to its arrangement between the topsheet and the absorbent core, the fluid flow control structure facilitates liquid handling into and within the absorbent article. In particular, the fluid flow control structure facilitates initial intake and distribution of absorbed fluid(s) by providing a space in which discharged fluid(s) can be rapidly captured and temporarily stored. Discharged fluid(s) readily pass through the topsheet, are wicked away from its top surface that face the wearer, and are absorbed into the fluid flow control structure. This means that the absorbed fluids are not in contact with the wearer’s skin and thus may provide the wearer with a feeling of dryness.

[0018] The fluid flow control structure is also designed to moderate the flow of absorbed fluid therethrough and into the absorbent layer(s) (e.g., absorbent core) arranged thereunder. By controlling the flow of fluid through the fluid flow control structure, the absorbent layer(s) may be given time to process and efficiently distribute the absorbed fluids to make full and effective use of the entire absorbent core. This provides efficient fluid management during use of the absorbentarticle regardless of any one or more of variance in the volume (e.g., high to low; low to high; moderate, etc.) of the discharge, whether the influx of fluid(s) is continuous or discontinuous (e.g., individual insults), the number of instances of fluid influx, and the saturation level of absorbed fluids in the absorbent article.

[0019] The first nonwoven layer may comprise a plurality of apertures and a plurality of protuberances forming a three-dimensional structure. Each aperture has a width in a transverse direction along a transverse axis (x) between opposing first and second side walls. Each aperture also extends a length in a thickness direction along a z-axis between a top end and a bottom end. The three-dimensional apertured structure may assist to direct the flow absorbed fluid into and through the fluid flow control structure. The apertures and the protuberances may also, in certain non-limiting exemplary embodiments, be arranged to restrict or deter fluid that has been absorbed into the absorbent article back through the fluid flow control structure toward the topsheet.

[0020] In non-limiting exemplary embodiments, at least most of the apertures may have a funnelshape. Each aperture may preferably have a width that tapers from a maximum transverse width at the top end to a minimum transverse width at the bottom end. Not only can apertures having a funnel-shape create fast inlet for fluid, such apertures may also hinder fluid flow back through the fluid flow control structure and toward the topsheet, even when pressure, such as a compressive force, is applied to the layers of the absorbent article, thereby advantageously contributing to the retention of absorbed fluids in the absorbent article. It further follows in such instances that the protuberances between the apertures are arranged such that the top end is arranged adjacent or proximal to the topsheet and the bottom end is arranged adjacent or proximal to the absorbent core. As noted above, the apertures and the protuberances may be arranged in order to advantageously direct the flow of absorbed fluid(s) away from the topsheet and into the absorbent core.

[0021] The apertures are also generally sized to facilitate fluid transport through the fluid flow control structure and to deter reverse flow of absorbed fluid(s) back through the fluid flow control structure toward the topsheet. As such, the apertures and the protuberances may contribute to minimizing the occurrence of surface wetness at the wearer facing of the topsheet, and by extension, improving rewet performance of the absorbent article.

[0022] In exemplary non-limiting embodiments, the first perforated nonwoven layer may comprise at least 4 apertures per cm2. The first perforated nonwoven layer may comprise 4 to 20, or 6 to 11 apertures per cm2. It is to be understood that the number of apertures per square centimeter provided in the first nonwoven layer may be adapted by one or ordinary skill in the art depending on any one or more of the type of absorbent article, the intended use thereof, the number layer(s) forming the absorbent article, and the source material(s).

[0023] The fluid flow control structure may, in certain non-limiting embodiments, have a basis weight in a range of 65 to 300 gsm, preferably from 110 to 250 gsm. However, it is to be understood that the basis weight of the fluid flow control structure may be adapted by one or ordinary skill in the art depending on any one or more of the type of absorbent article, the intended use of the absorbent article, the number layer(s) forming the absorbent article, and the source material(s).

[0024] The first perforated nonwoven layer may, in certain non-limiting embodiments, have a basis weight in a range of 20 to 100 gsm, preferably from 35 to 85 gsm. However, it is to be understood that the basis weight of the fluid flow control structure may be adapted by one or ordinary skill in the art depending on any one or more of the type of absorbent article, the intended use of the absorbent article, the number layer(s) forming the absorbent article, and the source material(s).

[0025] In terms of structure, the fluid flow control structure may be a nonwoven laminate comprising at least a first nonwoven layer being perforated and a second nonwoven layer being perforated or non-perforated. The first perforated nonwoven layer may be laminated directly to the second nonwoven layer with an adhesive. The adhesive may function as both a stiffening member and a bonding member. If the second nonwoven layer is non-perforated, the first nonwoven layer may preferably be perforated before being laminated together with the second nonwoven layer to form the nonwoven laminate of the fluid flow control structure. If also the second nonwoven layer is perforated, the first and second nonwoven layers may be first laminated and thereafter the nonwoven laminate may be perforated so as to perforate both the first and the second nonwoven layers in one perforating step.

[0026] Both the first and second nonwoven layers may comprise sustainable material(s) that is / are made from non-plastic material. Each nonwoven layer may comprise one or more of regenerated cellulose, cotton, lyocell, kapok and / or hemp in an amount of at least 90% by weight of the fluid flow control structure. Each nonwoven layer may comprise one or more of regenerated cellulose, cotton, lyocell, kapok and / or hemp in an amount of at least 95%, 97% or substantially by 100% weight of the fluid flow control structure.

[0027] In addition to environmental benefits attainable from using sustainable material(s) as a source material, both on the lifecycle of the absorbent articles described herein and the resources required to manufacture them, the fluid flow control structure according to the present disclosure have also been shown to provide structural advantages. For example, the fluid flow control structure demonstrates relatively high resilient properties. Stated in different terms, it is possible to obtain a fluid flow control structure using sustainable material(s) that exhibits a relatively high resistance to compression.

[0028] Having a fluid flow control structure that is resilient and / or has a relatively high resistance to compression, by extension, enables the fluid flow control structure to maintain its relative thickness (in the z-direction) even when subjected to compressive forces which may occur during normal use of the absorbent article. This resilience to compression and retention of the overall thickness of the fluid flow control structure further facilitates the provision and maintenance of a space arranged between the topsheet layer and absorbent layer(s) in which absorbed fluids can be retained with minimal to no risk of being released back to the surface of the topsheet and into contact with the wearer’s skin. Additionally, the resilience to compression and retention of the overall thickness of the fluid flow control structure may, in certain non-limiting embodiments, further serve to counteract and / or compensate for a decrease in the overall absorbent capacity and / or fluid retention level arising from substituting non-plastic material(s) in place of one or more conventionalsynthetic materials (e.g., non-plastic SAP for synthetic SAP) in one or more other layers of the absorbent article.

[0029] In certain non-limiting exemplary embodiments, the stiffening member is an adhesive. The stiffening member may comprise a hotmelt. It may be preferable, in exemplary embodiments according to the present disclosure, that the stiffening member is plastic-free and / or is not formed from plastic-based material(s). Further, the stiffening member contributes to increasing the overall resilience and / or compression-resistant of the fluid flow control structure. The incorporation of the stiffening member, an adhesive(s) or other coating, may assist in the creation of a nonwoven laminate structure that is relatively more stiff and non-compressible than a non-plastic material without stiffening member, such as an adhesive(s) or other coating.

[0030] The first and second nonwoven layers are, in exemplary, non-limiting embodiments, laminated together by an adhesive that is derivable from a renewable resource. It may be preferable, in certain non-limiting exemplary embodiments, that the adhesive is not sourced from plastic-based material(s) and / or is plastic-free. According to this embodiment, is the stiffening member also a bonding member.

[0031] The second nonwoven layer may be a perforated or a non-perforated nonwoven layer and may, in certain non-limiting embodiments, have a basis weight in a range of 25 to 100 gsm, preferably from 40 to 80 gsm. However, it is to be understood that the basis weight of the second nonwoven layer may be adapted by one or ordinary skill in the art depending on any one or more of the type of absorbent article, the intended use of the absorbent article, the number layer(s) forming the absorbent article, and the source material(s).

[0032] In certain exemplary non-limiting embodiments, the fluid flow control structure may further comprise a third nonwoven layer. Similar to the first and second nonwoven layers, the third nonwoven layer may also comprise sustainable material(s) that is / are made from non-plastic material. The third nonwoven layer may be perforated or non-perforated. The third nonwoven layer may, in certain non-limiting embodiments, have a basis weight in a range of 20 to 100 gsm, preferably from 35 to 85 gsm. According to one embodiment is the third nonwoven layer a similar layer as the first perforated nonwoven layer.

[0033] The fluid flow control structure may have a thickness in the z-direction of 0.4 to 2.0 mm at an applied pressure of 2 kPa.

[0034] Further, in certain exemplary embodiments, the thickness of the fluid flow control structure at an applied pressures of 2 kPa may be at least 70% of a thickness of the fluid flow control structure at an applied pressure of 1 kPa.

[0035] Similar to the fluid flow control structure, the absorbent core may also comprise sustainable materials. Particularly, it may be preferable in some non-limiting exemplary embodiments that the absorbent core is sourced from material(s) that is / are non-plastic and / or are plastic-free. For example, the absorbent core may comprise materials such as those including but not limited to cellulose fibers and superabsorbent materials derived from renewable resources such as regenerated cellulose, cotton, lyocell, kapok and / or hemp or the like.

[0036] In terms of source material(s), it is further contemplated that one or more certain material(s), particularly those that are plastic-based and / or contain plastic, may be specifically excluded from use in exemplary non-limiting embodiments of the absorbent articles described herein. For example, in some non-limiting embodiments, the absorbent core does not contain polyacrylic superabsorbent material (e.g., synthetic SAP).

[0037] As indicated above the absorbent articles described herein may be provided in any one of a number of different forms, including but not limited to a sanitary towel, a sanitary napkin, a panty liner, an incontinence pad, and an incontinence liner. It also envisioned, in certain exemplary nonlimiting embodiments, that the absorbent article(s) may comprise(s) a reusable part and a disposable part. More specifically, the reusable part may comprise a reusable outer cover that is preferably washable, and the disposable part may comprise a disposable insert that comprises the resilient fluid flow control structure and is preferably single use. In such non-limiting embodiments, it is to be understood that the reusable part and the disposable part are removably attached to each other, attachment of the reusable part and the disposable part may be any suitable attachment means, such as button and / or snap closure, a hook and loop closure, or the like. Following use, the disposable part my thus be detached from the reusable part so that it may be disposed of quickly and easily. Meanwhile, the reusable part may be cleaned and / or attached to a new disposable part. The absorbent article may therefore comprise an absorbent insert and a reusable outer cover wherein the absorbent insert is adaptable to be detachably secured in the reusable outer cover, and comprising a fluid flow control structure according to the present disclosure.

[0038] Method description and test resultCompressibility under a sequence of pressures (0.5 kPa, 1 .0 kPa and 2.0 kPa) has been evaluated according to the following procedure. The evaluated materials have been conditioned for at least four hours in a controlled environment set to 23°C + / - 1 °C and 50% + / - 5% relative humidity. When conditioning, single layers of the material rest flat and exposed. The test was made in this same environment. A representative sample was arranged flat on an even surface, and a spot is selected for thickness measurement. A thickness gauge foot (a square measuring 5 x 5 cm) exerting a pressure of 0.5 kPa was gently lowered onto the material. Thickness was read when the foot had rested on the material for 5 seconds, after which the foot was lifted. After a waiting time of one minute the thickness was measured again on the same spot, but now with a foot exerting a pressure of 1 .0 kPa. A minute later a final measurement was made under a pressure of 2.0 kPa.

[0039] Further objectives, features and advantages of the present absorbent article are described in the detailed description below with reference to the appended drawings.

[0040] Sample A was a fluid flow control structure according to the invention. Sample A was a laminate of a first nonwoven layer and a second nonwoven layer. Both nonwoven layers were made of 100 weight% of regenerated cellulose and each nonwoven layer had a basis weight of 25 gsm. The nonwoven layers were from Glatfelter. The first and the second nonwoven layers were laminated together by an adhesive named HB Fuller Lunatack D6312-ZP. The basis weight of adhesive on Sample A was 11 gsm. The adhesive was functioning as a stiffening member. Thelaminated nonwoven was thereafter apertured. Sample B was a reference fluid flow control structure. Sample B was also a laminate of a first nonwoven layer and a second nonwoven layer but without an adhesive as stiffening member. The first and second nonwoven layers were of same material from Glatfelter as Sample A (100 weight % viscose), and each nonwoven layer had a basis weight of 25 gsm.

[0041] Thickness resultThe thickness of Sample A at an applied pressure of 2 kPa was 71 % of the thickness at an applied pressure of 1 kPa, wherein the thickness of Sample B (reference fluid flow control structure) at an applied pressure of 2 kPa was only 50% of the thickness at an applied pressure of 1 kPa.Brief description of the drawings

[0042] The present invention will be discussed in more detail below, with reference to the attached drawings, in which:

[0043] Figure 1 shows a cross-section of an exemplary absorbent article according to the present disclosure; and

[0044] Figure 2 shows an exemplary fluid flow control structure.

[0045] Figure 3 shows an alternative exemplary fluid flow control structure.

[0046] Figure 4 shows an exploded perspective view of the fluid flow control structure according to Figure 3.Detailed description

[0047] The absorbent articles described herein are absorbent articles aimed for personal hygiene and may be, for example, a sanitary towel or sanitary napkin, a panty liner, an incontinence pad, incontinence liner or diaper. Such articles are commonly used for the acquisition and storage of discharged bodily exudates such as urine and menstrual fluid. The absorbent articles may be disposable, which means that they are intended for a single use and disposed thereafter, instead of being cleaned and reused. The absorbent article may also be an absorbent article comprising a reusable outer cover and an absorbent insert detachably attached to the outer cover.

[0048] A cross-section of an exemplary absorbent article in accordance with the present disclosure is shown Figure 1 . The absorbent article generally comprises four components: a liquid permeable topsheet 1 , a fluid flow control structure 2, an absorbent core 3, and a liquid-impermeable backsheet 4. Here also, the fluid flow control structure 2 provided is in the form of a nonwoven laminate. More specifically, the fluid flow control structure comprises a first nonwoven layer 21 and a second nonwoven layer 22. Structurally, the fluid flow control structure 2 and the absorbent core 3 are arranged between the topsheet 1 and the backsheet 4, with the first nonwoven layer 21 of the fluidflow control structure 2 arranged adjacent to the topsheet 1 and the second nonwoven layer 22 of the fluid flow control structure 2 arranged adjacent to the absorbent core 3. On its other side, the absorbent core 3 is arranged adjacent to the backsheet 4.

[0049] The topsheet 1 lies in direct contact with the wearer’s body and should therefore be soft and comfortable. The topsheet 1 can comprise a nonwoven material, e.g. spunbond, meltblown, carded, hydroentangled, wetlaid, etc. The nonwoven material may be composed of natural fibers, such as regenerated cellulose, cotton, lyocell, kapok and / or hemp. Regenerated cellulose may be viscose and / or lyocell. Apertured films may also be used as topsheet materials. In any case, suitable topsheet materials should be soft and non-irritating to the skin and be readily penetrable by bodily fluids, e.g. urine or menstrual fluid. The backsheet 4 lies in contact with the wearer’s garments. The backsheet 4 refers to the liquid impervious material forming the outer cover of the hygiene article. The backsheet 4 can comprise a film, a nonwoven material coated with a liquid impervious material, a hydrophobic nonwoven material, which resists liquid penetration, or a laminate of a film and a nonwoven material. The backsheet material may be breathable so as to allow vapor to escape from the absorbent core, while still preventing liquids from passing there through. Examples of breathable backsheet materials are porous polymeric films, nonwoven laminates of spunbond and meltblown layers and laminates of porous polymeric films and nonwoven materials. Particularly, it may be preferable in some non-limiting exemplary embodiments that the backsheet is sourced from materials) that is / are non-plastic. Suitable polymeric films may for example be composed of biobased PE, starch, PLA, PHA, PBAT or combinations thereof.

[0050] The absorbent core 3 is the absorbent structure of the article which acquires and stores bodily fluids and exudates. The absorbent core 3 may be of any conventional kind. Examples of commonly occurring absorbent materials are cellulosic fluff pulp, tissue, highly absorbent polymers (so called superabsorbents), absorbent foam materials, absorbent nonwoven materials or the like. It is common to combine cellulosic fluff pulp with superabsorbent polymers in an absorbent core. Superabsorbent polymers are water-swellable, water-insoluble organic or inorganic materials capable of absorbing at least about 20 times their own weight of an aqueous solution containing 0.9 weight percent of sodium chloride. With the movement away from conventional plastic-based source materials, organic materials suitable for use as a superabsorbent material may be derived from renewable resources, such as from example cellulose, starch, chitosan, protein, alginate, pectin, sugar and the like. The superabsorbent materials may be in any form suitable for use in absorbent composites including particles, fibers, flakes, spheres, and the like. A high absorption capacity is provided by the use of high amounts of superabsorbent material. Thin absorbent cores, which are common in for example baby diapers and incontinence guards, often comprise a compressed, mixed or layered structure of cellulosic fluff pulp and superabsorbent polymers. The size and absorbent capacity of the absorbent core may thus be varied to suit different product types, such as sanitary napkins for adult incontinent persons or panty liners.

[0051] In certain embodiments, the absorbent core 3 can be of unitary construction, whereby for example the manufacturing process can be simplified. The phrase "unitary construction" in the present context is intended to mean that the absorbent core 3 is constructed from essentially onetype of material, this being essentially the same material, or essentially the same combination of two or more materials throughout the absorbent core 3. Variations in density and concentration of the material may occur, but these are limited to those which may be obtained without incorporation of regions which have been formed separately and then physically joined to each other. For example, when the absorbent core comprises a matrix of hydrophilic fibers and superabsorbent material as described above, the relative concentrations of superabsorbent material and fibers may be different in different parts of the core. However, an absorbent core 3 of unitary construction does not comprise layers or laminates of different composition. Likewise, variations in the density or concentration of various components across the longitudinal direction, the transverse direction or the thickness direction of the absorbent core are acceptable, yet the core should not comprise areas or layers of different composition which are formed separately and later joined together.

[0052] In some non-limiting embodiments, the absorbent core 3 can have a multi-layered structure. In this sense, the absorbent core 3 can comprise a plurality of absorbent layers and / or absorbent members. When the absorbent core 3 comprises a plurality of absorbent layers and / or absorbent members, the absorbent layers and / or absorbent members may be equally sized or may differ in one or more dimensions. The fluid flow control structure 2 in figure 1 is a nonwoven laminate that is arranged between the topsheet 1 and the absorbent core 3 and may suitably be placed on top of the absorbent core 3. The fluid flow control structure 2 is adapted to quickly receive and temporarily store discharged fluid before it is absorbed by the absorbent core 3. The nonwoven layers may be composed of, for example spunlace nonwoven, needle punched nonwoven, resin bonded nonwoven, air through bonded nonwoven or combinations thereof. It is to be understood that the fluid flow control structure 2 can be formed from any one or more of the aforementioned materials, however, low density nonwoven materials may be particularly preferred in certain embodiments.Figure 2 depicts an exemplary fluid flow control structure 2 in accordance with the present disclosure. In this non-limiting example, the fluid flow control structure 2 is provided in the form of a nonwoven laminate having a first perforated nonwoven layer 21 and a second non-perforated nonwoven layer 22. The first perforated nonwoven layer 21 has a plurality of apertures 213. Each aperture 213 having a width in a transverse direction along a transverse axis (x) between opposing first and second side walls 2141 A, 2141 B and extending a length in a thickness direction along a z- axis from a top end 211 towards a bottom end 212, wherein the top end 21 1 is arranged adjacent to the topsheet 1 and the bottom end 212 is arranged adjacent to the second non-perforated nonwoven layer 22. Furthermore, each aperture 213 has a funnel-shape, and a width that tapers from a maximum transverse width at the top end 21 1 to a minimum transverse width at the bottom end 212.The fluid flow control structure 2 in figure 3 is a three-layer structure consisting of a non-perforated second nonwoven layer 22 that is sandwiched between a first perforated nonwoven layer 21 and a third perforated nonwoven layer 23. The first and third perforated nonwoven layers 21 , 23 are three- dimensionally formed layers, having penetrating apertures 213, 233. The first perforated nonwoven layer 21 has penetrating apertures 213 that originate in a top end 211 of the layer and extendtowards a bottom end 212 of the layer in the same way as the first perforated nonwoven layer in figure 2, so each aperture 213 has a funnel-shape, and a width that tapers from a maximum transverse width at the top end 211 to a minimum transverse width at the bottom end 212.The third perforated nonwoven layer 23 has instead penetrating apertures 233 with a width that tapers from a maximum transverse width at the bottom end 232 to a minimum transverse width at the top end 231 , wherein the top end 231 of the third perforated nonwoven layer 23 is arranged adjacent to the second non-perforated nonwoven layer 22 and the bottom end 232 is arranged adjacent to the absorbent core 3. The apertures 213 are tubular structures and are preferably funnel-shaped, as seen in figure 3. The distance between the top end and the bottom end is the thickness of the nonwoven layer. When fluid reaches the top end of the first nonwoven layer 21 , it spreads slightly on the surface of the top end before passing through the apertures 213 into the non-perforated second nonwoven layer 22. The non-perforated second nonwoven layer 22 offers very little resistance to fluid flow, whereby the fluid runs relatively freely in the non-perforated second nonwoven middle layer 22 until it is finally transported by gravity down to the third perforated nonwoven layer 23 where further downward movement is restricted by the third perforated nonwoven layer 23. A small amount of fluid may run out of the fluid flow control structure by entering the apertures in the third nonwoven perforated layer. However, most of the fluid will spread further on the bottom end surface 232 of the third nonwoven layer 23 by running in the interconnected channel network 230 that is formed between the protrusions, as illustrated in figure 3.

[0053] The fluid that is captured in the interconnected channel network 230 will generally not exit the fluid flow control structure until it reaches the edges of the fluid flow control structure or when the channel network 230 is saturated with fluid such that the fluid level raises above the height of the protrusions. Accordingly, the fluid will be distributed along the bottom end 232 of the third nonwoven layer 23 in all directions from the initial point of inlet.

[0054] Structurally, the first and third nonwoven layers 21 , 23 have a number of apertures 213, 233. As can be seen in Fig. 2, 3 and 4 each aperture is formed with a pair of opposing side walls 2041 A, 2041 B that are spaced a distance apart from each other in the transverse direction along a transverse axis (x) of the nonwoven layer. The width of each aperture can be defined by this distance in the transverse direction between its opposing side walls 2041 A, 2041 B. Further, each aperture 213, 233 also has a respective length between a top end 21 1 and a bottom end 212 in a thickness direction along a z-axis of the nonwoven layer.

[0055] Protuberances are arranged between the adjacent pairs of apertures. The respective top ends 214 of the protuberances are closed structures and contribute to controlling the flow of fluid through the fluid flow control structure.

[0056] As is shown in the figures, the apertures 213, 233 may have a conical shape, and it further follows in such instances that the apertures 213, 233 also have a width in the transverse direction (x) that tapers from a maximum transverse width to a minimum transverse width. In certain nonlimiting exemplary embodiments, it may be preferred that the maximum transverse width of the aperture 213 in the first apertured nonwoven layer 21 is arranged in the z-direction between the side walls at the respective top ends of two adjacent protuberances, and conversely, the minimumtransverse width of the aperture 213 is arranged between the side walls at the respective bottom ends 212 of the two adjacent protuberances in the first apertured nonwoven layer 21. By way of this arrangement, absorbed fluids may be funnelled in from the topsheet 1 through the fluid flow structure 2 and into the absorbent layer(s) 3 thereunder. Besides, having the maximum transverse width of the apertures arranged proximal to the fluid intake side (i.e., closer to the topsheet) facilitates a larger ingress of fluid upon intake. Inversely, having the minimum transverse width of the apertures 213 arranged proximal to the absorbent layer(s) 3 below the fluid flow control structure 2 may contribute to promoting increased fluid retention since passage of the absorbed fluids back through the fluid flow structure 2 is more restricted from re-entry into the aperture 213 by the narrowed minimum transverse width.

[0057] In addition, the respective bottom ends 212 of the protuberances in the first apertured nonwoven layer 21 each have an open structure between the opposing side walls 2141 A, 2141 B. Opposite to the closed top ends of the protuberances 214, the open bottom ends may help to facilitate retention of absorbed fluid(s) and deter the same from passing back through the fluid flow control structure 2 toward the topsheet 1 and into contact again with the wearer. This may encourage absorbed fluid to flow into the open space bounded by the top end and side walls of each protuberance rather than back through the relatively narrow transverse minimum width of the apertures.

[0058] Turning back briefly to Fig. 2, the first nonwoven layer 21 , and the second nonwoven layer 22 that form the nonwoven laminate of the fluid flow control structure 2 are laminated together one layer on top of each other in a stack. In this particular non-limiting exemplary embodiment, the second nonwoven layer forms the bottom of the stack. The first nonwoven layer 21 is laminated directly on top of the second nonwoven layer 22 with an adhesive.

[0059] It is to be understood that it is also contemplated for any embodiment of the absorbent articles described herein that the fluid flow control structure may be suitably dimensioned in the transverse and longitudinal directions (x, y) as desired, for example, based on the type and / or application of the absorbent article, by one of ordinary skill. In one non-limiting exemplary embodiment, the fluid flow control may have a length in the longitudinal direction (y) and a width in the transverse direction (x) that are equal to or shorter than a respective length and respective width of the absorbent core.While the invention has been described herein by reference to certain embodiments, it is to be understood that modifications in addition to those described herein may be made to the structures and techniques described herein without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, they are examples only and are not limiting upon the scope of the invention.

Claims

Claims1 . An absorbent article comprising a liquid permeable topsheet (1), a liquid impermeable backsheet (4), an absorbent core (3) arranged between the topsheet (1) and the backsheet (4), and a fluid flow control structure (2) arranged between the topsheet (1) and the absorbent core (3), wherein the fluid flow control structure (2) comprises at least a first nonwoven layer (21) comprising natural materials such as regenerated cellulose, cotton, lyocell, kapok and / or hemp in an amount of at least 90% by weight of the first nonwoven layer (21) , wherein the first nonwoven layer (21) is a three-dimensionally formed layer having a plurality of apertures (213) and comprising a stiffening member.

2. The absorbent article according to claim 1 , wherein the stiffening member is an adhesive or other coating.

3. The absorbent article according to claim 1 or claim 2, wherein the stiffening member is derivable from a renewable resource.

4. The absorbent article according to any of preceding claims, wherein the amount of the stiffening member is between 2.0 to 15.0 gsm.

5. The absorbent article according to any of the preceding claims, wherein each aperture (213) having a width in a transverse direction along a transverse axis (x) between opposing first and second side walls (2141 A, 2141 B) and extending a length in a thickness direction along a z-axis from a top end (211) towards a bottom end (212), wherein the top end (211) is arranged adjacent to the topsheet (1) and the bottom end (212) is arranged adjacent to the absorbent core (3).

6. The absorbent article according to preceding claim, wherein each aperture (213) has a funnelshape, and a width that preferably tapers from a maximum transverse width at the top end (211) to a minimum transverse width at the bottom end (212), the stiffening member is optionally applied at least on the top end surface (211) of the first nonwoven (21).

7. The absorbent article according to any one of claims 4 to 6, wherein each aperture (213) having a width in a transverse direction along a transverse axis (x) of between 0.5 and 4.0 mm, or preferably between 0.7 and 3.2 mm.

8. The absorbent article according to any one of claims 4 to 7, wherein the first nonwoven layer (21) comprises between 4 and 20 apertures per cm2, preferably between 6 and 11 apertures per cm2.9 The absorbent article according to any of preceding claims, wherein the first nonwoven layer (21) has a basis weight of from 20 to 100 gsm, preferably 35 to 85 gsm.

10. The absorbent article according to any of preceding claims, wherein the first nonwoven layer (21) is apertured and having an open area of 5-30%, preferably 10-25%.11 . The absorbent article according to any one of the preceding claims, wherein the fluid flow control structure (2) has a basis weight in a range of 65 to 300 gsm, preferably from 1 10 to 250 gsm.

12. The absorbent article according to any one of preceding claims, wherein the fluid flow control structure (2) is a nonwoven laminate comprising also at least a second nonwoven layer (22) having a basis weight being preferably 20-100 gsm.

13. The absorbent article according to claim 12, wherein the stiffening member also has the function of bonding the first and the second nonwoven layer together to a nonwoven laminate.

14. The absorbent article according to claim 12 or 13, wherein the second nonwoven layer (22) has no apertures.

15. The absorbent article according to any one of preceding claims, wherein the fluid flow control structure (2) is a three-layer structure consisting of the first perforated nonwoven layer (21) , a second non-perforated nonwoven layer (22) and a third perforated nonwoven layer (23), said second nonwoven layer being a non-perforated nonwoven layer sandwiched between said first perforated nonwoven layer (21) and said third perforated nonwoven layer (23).

16. The absorbent article according to claim 15, wherein the third nonwoven layer has a basis weight in a range of 20 to 100 gsm, preferably from 35 to 85 gsm.

17. The absorbent article according to any of the preceding claims, wherein the fluid flow control structure (2) has a thickness in a z-direction of 0.4 to 2.0 mm at an applied pressure of 2 kPa.

18. The absorbent article according to any of the preceding claims, wherein the thickness of the fluid flow control structure (2) at the applied pressure of 2 kPa is at least 70% of a thickness of the fluid flow control structure (2) at an applied pressure of 1 kPa.

19. The absorbent article according to any of the preceding claims, wherein the absorbent core (3) comprises cellulosic fibers and superabsorbent material derived from renewable resources, such as for example cellulose, starch, chitosan, protein, alginate, pectin, sugar.

20. The absorbent article according to any of the preceding claims, wherein the absorbent core (3) does not contain polyacrylic superabsorbent material.

21. An absorbent article having an absorbent insert and a reusable outer cover, wherein the absorbent insert is adaptable to be detachably secured in the reusable outer cover and comprising the fluid flow control structure (2) according to any of claims 1-20.

Images